Routing of meltwater from the Laurentide Ice Sheet during the Younger Dryas cold episode

ROOTH proposed that the Younger Dryas cold episode, which chilled the North Atlantic region from 11,000 to 10,000 yr BP, was initiated by a diversion of meltwater from the Mississippi drainage to the St Lawrence drainage system. The link between these events is postulated to be a turnoff, during the Younger Dryas cold episode, of the North Atlantic's conveyor-belt circulation system which currently supplies an enormous amount of heat to the atmosphere over the North Atlantic region. This turnoff is attributed to a reduction in surface-water salinity, and hence also in density, of the waters in the region where North Atlantic Deep Water (NADW) now forms. Here we present oxygen isotope and accelerator radiocarbon measurements on planktonic foraminifera from Orca Basin core EN32-PC4 which reveal a significant reduction in meltwater flow through the Mississippi River to the Gulf of Mexico from about 11,200 to 10,000 radiocarbon years ago. This finding is consistent with the record for Lake Agassiz which indicates that the meltwater from the southwestern margin of the Laurentide Ice Sheet was diverted to the northern Atlantic Ocean through the St Lawrence valley during the interval from ∼11,000 to 10,000 years before present (yr BP). © 1989 Nature Publishing Group

Elastin and collagen enhances electrospun aligned polyurethane as scaffolds for vascular graft

Mismatch in mechanical properties between synthetic vascular graft and arteries contribute to graft failure. The viscoelastic properties of arteries are conferred by elastin and collagen. In this study, the mechanical properties and cellular interactions of aligned nanofibrous polyurethane (PU) scaffolds blended with elastin, collagen or a mixture of both proteins were examined. Elastin softened PU to a peak stress and strain of 7.86&nbsp;MPa and 112.28&nbsp;% respectively, which are similar to those observed in blood vessels. Collagen-blended PU increased in peak stress to 28.14&nbsp;MPa. The growth of smooth muscle cells (SMCs) on both collagen-blended and elastin/collagen-blended scaffold increased by 283 and 224&nbsp;% respectively when compared to PU. Smooth muscle myosin staining indicated that the cells are contractile SMCs which are favored in vascular tissue engineering. Elastin and collagen are beneficial for creating compliant synthetic vascular grafts as elastin provided the necessary viscoelastic properties while collagen enhanced the cellular interactions. <br /

Using micro‑computed tomography to reveal the anatomy of adult Diaphorina citri Kuwayama (Insecta: Hemiptera, Liviidae) and how it pierces and feeds within a citrus leaf

The Asian citrus psyllid (ACP), Diaphorina citri, is a harmful pest of citrus trees that transmits Candidatus Liberibacter spp. which causes Huanglongbing (HLB) (citrus greening disease); this is considered to be the most serious bacterial disease of citrus plants. Here we detail an anatomical study of the external and internal anatomy (excluding the reproductive system) using micro-computed tomography (micro-CT). This is the frst complete 3D micro-CT reconstruction of the anatomy of a psylloid insect and includes a 3D reconstruction of an adult feeding on a citrus leaf that can be used on mobile devices. Detailed rendered images and videos support frst descriptions of coxal and scapus antennal glands and sexual diferences in the internal anatomy (hindgut rectum, mesothoracic ganglion and brain). This represents a signifcant advance in our knowledge of ACP anatomy, and of psyllids in general. Together the images, videos and 3D model constitute a unique anatomical atlas and are useful tools for future research and as teaching aids.Kansas State University (KSU)University of Granad