Raw materials and functional designs of Fishtail projectile points from southern Brazil

This study analyses the lithic landscape and the selection of rocks used to manufacture Fishtail points (FP) in southern Brazil, their designs, and some functional aspects. In order to identify the offer of lithic resources, we carried out several surveys throughout 15 months in 47 counties in the Southern Brazil covered by the Botucatú - Serra Geral Vulcano Sedimentary Complex. The lithic composition of numerous hill slopes, fallen rocks, and accumulations of pebbles and boulders in the riversides was evaluated. The results show that basalts (including a small proportion of andesites and rhyodacites-rhyolites), and silicified sandstones, are ubiquitous in the landscape. Conversely, non-translucent cherts are scarce, so their acquisition would have been time-consuming. However, these local cherts were the rocks mostly used to manufacture these points, being another example of the selectivity for high quality rocks by Paleoamerican hunter-gatherers. The same cherts selected in southern Brazil to produce the FP were used to manufacture other point-types by local hunter-gatherers of the early and middle Holocene grouped in the so-called “Umbú Tradition”. Not a single FP of the entire collection analyzed here was made from silicified limestones, which is one of the most common raw materials among the Uruguayan FPs, nor were they made from quartzites as were most of the FPs of the Pampean plains. Regarding to the designs of these projectiles, some morphotypes appear to have been designed to produce multiple injuries through successive thrusts and withdrawals in the bodies of the prey, while in others, the design seems to have favoured penetration and fixation on the prey, suggesting in this case, a single shot technique for each projectile. As the maintenance process unfolded, especially for points below ~ 80 mm in length, they show features that negatively impacted their efficiency, including distinct asymmetries, somewhat open front angles, a decrease in the cutting perimeter and cross-sectional area, an increase in the bevel angle of the blade edges, and a tendency to a conical cross-section. Behaviours intended to counteract these problems were maximizing the length of the leading edge, maintaining the symmetry and the triangular blade resting on straight shoulders, and maintaining the aerodynamic properties as much as it were possible, in order to improve their lethality and the fixation capacity. Beyond these rejuvenation processes, three different morphotypes of points appear to be included within the sample. The first includes points over 120 mm and ~ 80 g in weight, with triangular or slightly lanceolate limbs, which mostly present straight shoulders, but there are also examples of rounded shoulders. The second design corresponds to projectiles between 110 and 87 mm and ~30 g in weight, with triangular or slightly lanceolate blades and straight shoulders. The third design presents the classic shape of these projectiles, with a fish silhouette, with maximum lengths below 90 mm, with a more robust and conceptually different design, where the angles of the edges of the blades and of the shoulders are equal, perhaps with the intention to facilitate the spear withdrawal to produce multiple injuries.

Nonlinear vibration and stability analysis of a size-dependent viscoelastic cantilever nanobeam with axial excitation

In the present paper, nonlinear forced vibrations of an axial moving nanobeam which is vertically influenced by an external harmonic excitation and gravity is analyzed by considering the effects of linear damping. Considering certain assumptions, a nonlinear Euler-Bernoulli beam theory is developed. With the implementation of the nonlocal elasticity theory, the governing integro-partial-differential equation is obtained by using the Hamilton principle. The multiple scale method is employed to obtain a steady-state response for the size-dependent viscoelastic nanobeam with fixed-free boundary conditions. Subsequently, the trivial and non-trivial steady-state response and the bifurcation point types are examined. Finally, the effects of damping coefficient and nonlocal parameter on stability and bifurcation of trivial and non-trivial solutions are studied. It is found that the effect of nonlocal parameter on the steady-state response and the bifurcation point types is quite important.

Types of trigonometric points in Slovenia

In this paper, the historical development context of the trigonometric network point types in Slovenia from 1810 onwards is presented. Examples of different trigonometric point types still seen in the field are shown, with regard to the institution that carried out the field marking of the specific state trigonometric network. The city trigonometric network of Ljubljana, which was established in 1955–1956, is also presented. Furthermore, triangulation and comparator bases are mentioned as well, which remain marked with permanent pillars. As examples of the oldest still-standing trigonometric points, the following are mentioned: 303 Veliki Javornik (2nd order) with the engraved year 1823 and 329 Limberk (2nd order) with the engraved year 1903.

Well-definedness and observational equivalence for inductive–coinductive programs

We define notions of well-definedness and observational equivalence for programs of mixed inductive and coinductive types. These notions are defined by means of tests formulas which combine structural congruence for inductive types and modal logic for coinductive types. Tests also correspond to certain evaluation contexts. We define a program to be well-defined if it is strongly normalizing under all tests, and two programs are observationally equivalent if they satisfy the same tests. We show that observational equivalence is sufficiently coarse to ensure that least and greatest fixed point types are initial algebras and final coalgebras, respectively. This yields inductive and coinductive proof principles for reasoning about program behaviour. On the other hand, we argue that observational equivalence does not identify too many terms, by showing that tests induce a topology that, on streams, coincides with usual topology induced by the prefix metric. As one would expect, observational equivalence is, in general, undecidable, but in order to develop some practically useful heuristics we provide coinductive techniques for establishing observational normalization and observational equivalence, along with up-to techniques for enhancing these methods.

Paleoindians in the South Carolina Coastal Plain

The state of South Carolina is examined by the physiographic provinces of Mountains, Piedmont, and Coastal Plain using established Paleoindian projectile point types and their geographic distributions by raw materials. Foraging ranges are reconstructed. There is a substantial drop in post-Clovis point frequencies, as seen elsewhere in the Southeast, with a great increase by Dalton times. Younger Dryas age environmental changes are reviewed, with late Pleistocene flora and fauna changes noted. Starting in Dalton times, sea level rise appears to have affected settlement strategies due to the inundation of the primary resource habitats of the Coastal Plain. The Piedmont Transhumance hypothesis is offered as an explanation of these changes.