Matthew Baillie's specimens and engravings

In 1799, Matthew Baillie, William Hunter's nephew, published his famous atlas of pathology. It was entitled A Series of Engravings Accompanied with Explanations which are Intended to Illustrate the Morbid Anatomy of Some of the Most Important Parts of the Human Body. The present study aims to match the illustrations to extant specimens in the collections of William and John Hunter, preserved at the University of Glasgow and at the Royal College of Surgeons of England respectively. Baillie's book contains 10 fasciculi, consisting of 73 plates and 206 figures. The specimens Baillie illustrated came from his own collection and those of ten others, including his uncles, William and John Hunter. The book was illustrated by William Clift and engraved by James Basire, William Skelton and James Heath. Excluding eight illustrations of intestinal worms where the provenance of the specimens is uncertain, a total of 98 specimens from William Hunter's collection were illustrated in 104 figures. Eight of the specimens were calculi impossible to identify specifically. Excluding worms and calculi, 72 of William Hunter's specimens illustrated by Baillie are extant in the Hunterian Collection at the University of Glasgow. All but one of the 20 specimens illustrated that had belonged to John Hunter were identified in the on-line catalogue of the Royal College of Surgeons of England. Baillie's own collection was destroyed when the Royal College of Surgeons of England was bombed in 1941. Baillie is credited with being the first to produce an illustrated systematic textbook of morbid anatomy and probably the first to illustrate emphysema and transposition of the great vessels. His book, however, was not comprehensive. It did not cover a number of topics such as muscles and bones and there is little coverage of the nervous system. Baillie's book, however, was an original concept as an atlas of morbid anatomy and showed his deep insight into pathology

Late-Quaternary history of high-elevation vegetation in the White Mountains of New Hampshire

The White Mountains were deglaciated before 13 000 yr BP. From 13 000 to 11 750 yr BP a barren periglacial desert covered the highest altitudes. Tundra vegetation occupied the lower slopes and valleys. Mean annual temperature was 5-10°C colder than today. Sparse tundra vegetation surrounded all 4 high-elevation sites from 11 750 to 10 300 yr ago and several taxa, particularly Artemisia and Caryophyllaceae, indicate disturbance. Summits were subjected to intense periglacial activity. The mean annual temperature was 4-6°C lower than present. By 10 000 yr BP shrubs such as willow, juniper, and dwarf birch had invaded the tundra at Lake of the Clouds. Spruce woodland dominated the lower slopes and valleys. At 10 300 yr BP spruce populations arrived at high-elevation sites. Macrofossils of fir, birch, and shrubs also occur in sediments of this age. The temperature increased to or exceeded modern levels. Tree species did not reach the Franconia Notch sites until 9750 yr BP. At these sites establishment of subalpine forests spanned a much shorter time period. Forests with poplar, spruce, and birch replaced the spruce woodlands of low elevations. Subalpine fir forests became well established by 9000 yr BP. At the alpine site, fir trees were more abundant and treeline higher than today from 10 300 to 5000 yr BP. After 5000 yr BP, the pollen percentages of alpine indicators increased and numbers of fir macrofossils dropped. Treeline is a poor temperature indicator because wind and moisture are the major factors determining its position. Taxa of the Northern Hardwood Forest arrived at lower elevations by 6500 yr BP, but the zones of modern vegetation became established only after 2000 yr BP when spruce populations expanded at low elevations. -from Autho

Oxygen-related traps in pentacene thin films: Energetic position and implications for transistor performance

We studied the influence of oxygen on the electronic trap states in a pentacene thin film. This was done by carrying out gated four-terminal measurements on thin-film transistors as a function of temperature and without ever exposing the samples to ambient air. Photooxidation of pentacene is shown to lead to a peak of trap states centered at 0.28 eV from the mobility edge, with trap densities of the order of 10(18) cm(-3). These trap states need to be occupied at first and cause a reduction in the number of free carriers, i.e. a consistent shift of the density of free holes as a function of gate voltage. Moreover, the exposure to oxygen reduces the mobility of the charge carriers above the mobility edge. We correlate the change of these transport parameters with the change of the essential device parameters, i.e. subthreshold performance and effective field-effect mobility. This study supports the assumption of a mobility edge for charge transport, and contributes to a detailed understanding of an important degradation mechanism of organic field-effect transistors. Deep traps in an organic field-effect transistor reduce the effective field-effect mobility by reducing the number of free carriers and their mobility above the mobility edge.Comment: 13 pages, 14 figures, to be published in Phys. Rev.

Analysis of systems hardware flown on LDEF. Results of the systems special investigation group

The Long Duration Exposure Facility (LDEF) was retrieved after spending 69 months in low Earth orbit (LEO). LDEF carried a remarkable variety of mechanical, electrical, thermal, and optical systems, subsystems, and components. The Systems Special Investigation Group (Systems SIG) was formed to investigate the effects of the long duration exposure to LEO on systems related hardware and to coordinate and collate all systems analysis of LDEF hardware. Discussed here is the status of the LDEF Systems SIG investigation through the end of 1991

Paleovegetation and Paleoclimatic Changes in the Yukon at 6 ka BP

The most recent paleoenvironmental change to affect the Yukon centres around 6.0 ka. In the forested southern Yukon, black spruce (Picea mariana) and green alder (Alnus crispa) expanded their populations at most sites between 6.5 and 6.0 ka. Even in the semi-arid region of SW Yukon these species increased their populations, although slightly later at 5.5 ka. These vegetation changes in the south imply cooler and wetter growing seasons, i.e. more mesic conditions. In the region of the upper Blackstone River of central Yukon, the modern vegetation consists of shrub tundra with scattered groves of white spruce (Picea glauca) and even fewer black spruce. Open forests of predominantly white spruce occupied the region as early as 9.5 ka, but between 6.5 and 6.0 ka white spruce declined as black spruce became the dominant tree, coincidentally with an increase in green alder. By 5.0 ka the vegetation had acquired its modern composition. As in the south, these changes imply cooling. Less evidence is available on the expansion of alder and black spruce in the northern Yukon. Both species increased in forested areas (forest-tundra) at 6.0 ka. These changes again imply cooling. Because both black spruce and green alder were present in Yukon well before 6 ka, these vegetation changes cannot be ascribed to migration lags.Les changements apportés à la paléovégétation et au paléoclimat du Yukon à 6 ka BP. Au Yukon, les changements environnementaux les plus récents se sont produits vers 6 ka. Dans les zones forestières du sud du Yukon, l'épinette noire (Picea mariana) et l'aulne crispé (Alnus crispa) ont vu leur population augmenter entre 6,5 et 6 ka dans la plupart des sites. Même dans la région semi-aride du sud-ouest du Yukon, ces espèces ont connu une augmentation, bien qu'elle se soit produite plus tard, soit vers 5,5 ka. Ces changements dans la végétation méridionale du Yukon signalent l'avènement de saisons végétatives plus fraîches et plus humides, c'est-à-dire des conditions plus mésiques. Dans la région du cours supérieur de la Blackstone River, au centre du Yukon, Ia végétation moderne se compose d'une toundra arbustive parsemée ça et là de colonies d'épinettes blanches (Picea glauca) et de rares épinettes noires. Les forêts ouvertes dominées par l'épinette blanche peuplaient la région jusqu'à 9,5 ka, mais entre 6,5 et 6 ka, l'épinette blanche a décliné au profit de l'épinette noire, en concomitance avec une augmentation de l'aulne crispé. Vers 5 ka, la végétation avait acquis son caractère moderne. Tout comme au sud, ces changements impliquent un refroidissement. Il existe moins d'indices quant à l'expansion de l'aulne et de l'épinette noire dans le nord du Yukon. Les deux espèces se sont répandues dans les zones forestières (toundra forestières) à 6 ka. Encore une fois, il dut y avoir refroidissement. Puisque l'épinette noire et l'aulne crispé étaient présents dans le Yukon bien avant 6 ka, on ne peut attribuer ces changements enregistrées par la végétation à des décalages migratoires.Palàovegetation und palâoklimatische Verânderungen im Yukon um 6 ka v.u.Z. Die jùngsten Palâoumweltverànderungen im Yukon sind um etwa 6.0 ka geschehen. Im bewaldeten sùdlichen Yukon haben Schwarzfichte (Picea mariana) und grùne Erie (Alnus crispa) ihre Population an den meisten Plàtzen zwischen 6.5 und 6.0 ka erhôht. Selbst in der halbtrockenen Region von Sùdwest-Yukon haben dièse Arten ihre Populationen erhôht, wenn auch etwas spâter, um 5.5 ka. Dièse Vegetations-Wechsel im Sùden weisen auf kùhlere und feuchtere Wachstumszeiten, d.h. mehr mittlere Bedingungen. Im Gebiet des oberen Laufs des Blackstone River von Zentral-Yukon besteht die moderne Vegetation aus Busch-Tundra mit verstreuten Wâldchen von WeiBfichte (Picea glauca) und noch weniger Schwarzfichte. Offene Wàlder vor allem mit WeiBfichte bevôlkerten die Region so fruh wie 9.5 ka, aber zwischen 6.5 und 6.0 ka nahm die WeiBfichte ab, wàhrend die Schwarzfichte der beherrschende Baum wurde, begleitet von einer Zunahme von grùner Erie. Um 5.0 ka hatte die Vegetation ihre moderne Zusammensetzung erreicht. Wie im Sùden beinhalten dièse Verânderungen eine Abkùhlung. Ùber die Ausdehnung von Erie und Schwarzfichte im nôrdlichen Yukon gibt es weniger Belege. Beide Arten nahmen in bewaldeten Gebieten (Wald-Tundra) um 6.0 ka zu. Auch hier bedeuten die Wechsel eine Abkùhlung. Da beide, Schwarzfichte und grùne Erie, lange vor 6 ka im Yukon vorhanden waren, kann man dièse Vegetationswechsel nicht Verzôgerungen bei der Wanderung zuschreiben

Reversion of forest to tundra in the central Yukon

Pollen and plant macrofossil analyses of sediments from 3 sites that are presently in shrub tundra provide a record of former forest establishment. Shrub tundra with groves and gallery forests of balsam poplar Populus balsamea occupied the region between 10 000-8000 BP. At 9400 BP white spruce Picea glauca populations expanded, and open white spruce woodlands persisted until 6500 BP when black spruce Picea mariana and green alder Alnus viridis populations increased, resulting in open spruce woodlands with a distribution of species probably similar to that commonly found today in the northern boreal forest: white spruce on drier S-facing slopes and on alluvial sites with balsam poplar, and black spruce on colder, wetter sites on N-facing slopes and valley bottoms. At 5000 BP forest began to revert to shrub tundra, abruptly then more gradually. The modern groves of (mostly white) spruce are probably relict populations surving in favorable microsites. The ground vegetation apparently behaved independently of the tree populations. -from Author

Crystal growth in fused solvent systems

The successful nucleation of bismuth germanate, B12GeO20 on a high quality seed and the growth of regions of single crystals of the same orientation of the seed are reported. Lead germanate, Pb5Ge3O11 was also identified as a ferroelectric crystal with large electrooptic and nonlinear optic constants. Solvent criteria, solvent/development, and crystal growth are discussed, and recommendations for future studies are included