Fluting is a technological and morphological hallmark of some of the most iconic North American Paleoindian stone points. Through decades of detailed artifact analyses and replication experiments, archaeologists have spent considerable effort reconstructing how flute removals were achieved, and they have explored possible explanations of why fluting was such an important aspect of early point technologies. However, the end of fluting has been less thoroughly researched. In southern North America, fluting is recognized as a diagnostic characteristic of Clovis points dating to approximately 13,000 cal yr BP, the earliest widespread use of fluting. One thousand years later, fluting occurs more variably in Dalton and is no longer useful as a diagnostic indicator. How did fluting change, and why did point makers eventually abandon fluting? In this article, we use traditional 2D measurements, geometric morphometric (GM) analysis of 3D models, and 2D GM of flute cross sections to compare Clovis and Dalton point flute and basal morphologies. The significant differences observed show that fluting in Clovis was highly standardized, suggesting that fluting may have functioned to improve projectile durability. Because Dalton points were used increasingly as knives and other types of tools, maximizing projectile functionality became less important. We propose that fluting in Dalton is a vestigial technological trait retained beyond its original functional usefulness.

Introduction and regular application of multiplex polymerase chain reaction analysis of bronchoalveolar specimens for community-acquired respiratory viruses in January 2017 led to the identification of adenovirus in multiple patients in a surgical intensive unit in July 2017, which was attributed to a pseudo-outbreak.

The multicomponent Dry Creek site, located in the Nenana Valley, central Alaska, is arguably one of the most important archaeological sites in Beringia. Original work in the 1970s identified two separate cultural layers, called Components 1 and 2, thought to date to the terminal Pleistocene and suggesting that the site was visited by Upper Paleolithic huntergatherers between about 13,000 and 12,000 calendar years before present (cal B.P.). The oldest of these became the typeassemblage for the Nenana complex. Recently, some have questioned the geoarchaeological integrity of the site's early deposits, suggesting that the separated cultural layers resulted from natural postdepositional disturbances. In 2011, we revisited Dry Creek to independently assess the site's age and formation. Here we present our findings and reaffirm original interpretations of clear separation of two terminal Pleistocene cultural occupations. For the first time, we report direct radiocarbon dates on cultural features associated with both occupation zones, one dating to 13,485-13,305 and the other to 11,060-10,590 cal B.P.

This article presents results from the first 3 rounds of an international intercomparison of measurements of Δ14CO2 in liter-scale samples of whole air by groups using accelerator mass spectrometry (AMS). The ultimate goal of the intercomparison is to allow the merging of Δ14CO2 data from different groups, with the confidence that differences in the data are geophysical gradients and not artifacts of calibration. Eight groups have participated in at least 1 round of the intercomparison, which has so far included 3 rounds of air distribution between 2007 and 2010. The comparison is intended to be ongoing, so that: a) the community obtains a regular assessment of differences between laboratories; and b) individual laboratories can begin to assess the long-term repeatability of their measurements of the same source air. Air used in the intercomparison was compressed into 2 high-pressure cylinders in 2005 and 2006 at Niwot Ridge, Colorado (USA), with one of the tanks “spiked” with fossil CO2, so that the 2 tanks span the range of Δ14CO2 typically encountered when measuring air from both remote background locations and polluted urban ones. Three groups show interlaboratory comparability within l% for ambient level Δ14CO2. For high CO2/low Δ14CO2 air, 4 laboratories showed comparability within 2%. This approaches the goals set out by the World Meteorological Organization (WMO) CO2 Measurements Experts Group in 2005. One important observation is that single-sample precisions typically reported by the AMS community cannot always explain the observed differences within and between laboratories. This emphasizes the need to use long-term repeatability as a metric for measurement precision, especially in the context of long-term atmospheric monitoring.

1. ‘Resistant’ and ‘susceptible’ species of animals appear to be more or less equally susceptible to lung infection with equal doses of tubercle bacilli. Therefore it is pertinent to ask whether recognized natural differences in species resistant are in fact significant. For example, in terms of death rates (i.e. of overall resistance) the C57 mouse is at least as susceptible to tuberculosis as the guinea-pig and much more so than man.

2. Resistant, moderately susceptible and susceptible strains of mice as determined by death rates when exposed to large infecting doses, were equally susceptible to intranasal infection with small numbers of tubercle bacilli.

3. A state of tolerance of the parasite by the host lasting for about 3 weeks was observed in all mouse strains, regardless of ultimate strain resistance.

4. Pre-allergic deaths commenced in all groups when the tuberculous processes left insufficient normal lung to support life, but the deaths stopped first in the resistant strain and last in the susceptible strain, coinciding approximately in each strain with the onset of allergy.

5. Acquired immunity, once established, appeared not to vary in quality from one mouse strain to another, at least during 3 months' observation.

6. Racial or strain variations in the resistance of mice to tuberculosis are therefore natural, only in the sense that speed of onset of acquired immunity is probably genetically determined for each strain.

7. It is suggested that both species and racial variations in natural resistance to pulmonary infection are insignificant. Differences in the subsequent course of the disease appear to be explainable by the rapidity, efficiency and duration of the acquired immune response.