Histology and ultrastructure of a tissue-engineered collagen meniscus before and after implantation

The collagen meniscus implant (CMI) is a tissue-engineering technique designed to stimulate regeneration of meniscus-like tissue in cases of irreparable tears or previous meniscectomy. CMI morphology was investigated before and after implantation by light microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). In a case series biopsy specimens were harvested from four patients who underwent a second arthroscopic look 6 months after placement of the CMI. CMI sections appeared composed of parallel connective laminae of 10-30 mu m, connected by smaller bundles (5-10 mu m). This connective network formed lacunae with diameters between 40 and 60 mu m. At greater magnification, the walls of the lacunae demonstrated tightly packed and randomly distributed collagen fibrils, with diameters ranging from 73 to 439 nm. In the biopsy specimens, the lacunae were filled with connective tissue that contained newly formed vessels and fibroblast-like cells, presenting an abundant rough endoplasmic reticulum and several mitochondria. In the extracellular matrix, the collagen fibrils showed uniform diameters (126 nm +/- 32 nm). The original structure of CMI was still recognizable, and no inflammatory cells were detected within the implant. The morphological findings of this case series demonstrate that CMI provides a three-dimensional scaffold suitable for colonization by precursor cells and vessels and leading to the formation of a fully functional tissue

An Assessment of the Impact of Hafting on Paleoindian Point Variability

It has long been argued that the form of North American Paleoindian points was affected by hafting. According to this hypothesis, hafting constrained point bases such that they are less variable than point blades. The results of several studies have been claimed to be consistent with this hypothesis. However, there are reasons to be skeptical of these results. None of the studies employed statistical tests, and all of them focused on points recovered from kill and camp sites, which makes it difficult to be certain that the differences in variability are the result of hafting rather than a consequence of resharpening. Here, we report a study in which we tested the predictions of the hafting hypothesis by statistically comparing the variability of different parts of Clovis points. We controlled for the potentially confounding effects of resharpening by analyzing largely unused points from caches as well as points from kill and camp sites. The results of our analyses were not consistent with the predictions of the hypothesis. We found that several blade characters and point thickness were no more variable than the base characters. Our results indicate that the hafting hypothesis does not hold for Clovis points and indicate that there is a need to test its applicability in relation to post-Clovis Paleoindian points

A Morphometric Assessment of the Intended Function of Cached Clovis Points

A number of functions have been proposed for cached Clovis points. The least complicated hypothesis is that they were intended to arm hunting weapons. It has also been argued that they were produced for use in rituals or in connection with costly signaling displays. Lastly, it has been suggested that some cached Clovis points may have been used as saws. Here we report a study in which we morphometrically compared Clovis points from caches with Clovis points recovered from kill and camp sites to test two predictions of the hypothesis that cached Clovis points were intended to arm hunting weapons: 1) cached points should be the same shape as, but generally larger than, points from kill/camp sites, and 2) cached points and points from kill/camp sites should follow the same allometric trajectory. The results of the analyses are consistent with both predictions and therefore support the hypothesis. A follow-up review of the fit between the results of the analyses and the predictions of the other hypotheses indicates that the analyses support only the hunting equipment hypothesis. We conclude from this that cached Clovis points were likely produced with the intention of using them to arm hunting weapons

Late preceramic farmer-foragers in southeastern Arizona : a cultural and ecological consideration of the spread of agriculture into the arid southwestern United States

This study investigates the transition from hunting and gathering economies to mixed economies involving both agriculture and hunting and gathering. Specifically, the problem of when, why, and how the transition to agriculture occurred in the arid-semiarid river basins of southeastern Arizona is explored. Modern environmental conditions are described, and the nature and sources of climatic, biotic, and fluvial systemic variability are considered. Anthropological and ecological models of hunter-gatherer adaptations to arid environments are used to reconstruct the general subsistence economy of preagricultural societies in the region, and to portray the process of the spread of agricultural production strategies. Two models of the transition are presented, one involving the adoption of agriculture by indigenous hunting-gathering societies, and the other involving the arrival of immigrant societies already practicing agriculture to a significant degree. Previous studies of the transition to agriculture in the American Southwest are reviewed, and new data are presented from excavated Late Archaic (ca. 3000-2000 BP) sites in southeastern Arizona. These data show that agriculture appeared by at least 2800 BP in this area, and that it spread rapidly across the American Southwest. It was already an important subsistence strategy and was associated with semisedentary village sites that have no known predecessors in the archaeological record. It is concluded that the adoption of agriculture, with its associated storage technology, is an important strategy by which human populations can mitigate some of the risks associated with foraging in an environment characterized by predictable seasonal variation in resource availability and unpredictable, climatically-induced fluctuations in the productivity of wild resources over time.hydrology collectio

A Unified Reduced Order Model for Standing Balance Captures Biological Balance Strategy Preferences

The 9.5th international symposium on Adaptive Motion of Animals and Machines. Ottawa，Canada (Virtual Platform). 2021-06-22/25. Adaptive Motion of Animals and Machines Organizing Committee

Pulmonary thromboemboli : a case of acute respiratory distress in a Shih Tzu : recognition, diagnosis, and treatment options

Senior seminar (D.V.M.) -- Cornell University, 2003. Includes bibliographical references (leaves 14-15).Pulmonary thromboembolism is an uncommon but likely under-diagnosed condition in small animal medicine owing to both lack of awareness and difficulty in making an antemortum diagnosis (1). Pulmonary thromboembolism (PTE) occurs when a thrombus, thrombi, embolism, or emboli causes occlusion of one or more pulmonary arteries (1). Besides hypoxemia, this occlusion of the perfusion to the lungs can result in severe pulmonary hypertension, eventually leading to right sided heart failure (cor pulmonale.) Because of this ventilation/perfusion mismatch and secondary right-sided heart failure, patients with pulmonary thromboembolism often present in acute respiratory distress. Pulmonary thromboembolism carries with it a guarded to grave prognosis, despite proper diagnosis, intervention, and treatment. The goal of this report is to use a real case of pulmonary thromboembolism to distinguish pulmonary thromboemboli from other causes of acute respiratory distress; to identify common presenting complaints and associated clinical signs, physical exam findings, and predisposing factors for pulmonary thromboemboli; and to discuss diagnostic and treatment options available.Dr. Jason Pinta