The distribution of Transverse Aeolian Ridges on Mars

Abstract not available

Fast Synchronization of Perpetual Grouping in Laminar Visual Cortical Circuits

Perceptual grouping is well-known to be a fundamental process during visual perception, notably grouping across scenic regions that do not receive contrastive visual inputs. Illusory contours are a classical example of such groupings. Recent psychophysical and neurophysiological evidence have shown that the grouping process can facilitate rapid synchronization of the cells that are bound together by a grouping, even when the grouping must be completed across regions that receive no contrastive inputs. Synchronous grouping can hereby bind together different object parts that may have become desynchronized due to a variety of factors, and can enhance the efficiency of cortical transmission. Neural models of perceptual grouping have clarified how such fast synchronization may occur by using bipole grouping cells, whose predicted properties have been supported by psychophysical, anatomical, and neurophysiological experiments. These models have not, however, incorporated some of the realistic constraints on which groupings in the brain are conditioned, notably the measured spatial extent of long-range interactions in layer 2/3 of a grouping network, and realistic synaptic and axonal signaling delays within and across cells in different cortical layers. This work addresses the question: Can long-range interactions that obey the bipole constraint achieve fast synchronization under realistic anatomical and neurophysiological constraints that initially desynchronize grouping signals? Can the cells that synchronize retain their analog sensitivity to changing input amplitudes? Can the grouping process complete and synchronize illusory contours across gaps in bottom-up inputs? Our simulations show that the answer to these questions is Yes.Office of Naval Research (N00014-01-1-0624); Air Force Office of Scientific Research (F49620-01-1-03097

Gastric tube ulcer perforating the pericardium after subtotal esophagectomy [Perforacija ulkusa želučanog supstituta u perikard nakon subtotalne ezofagektomije]

Subtotal esophagectomy with retrosternal transposition of the gastric tube to the neck was performed in a 62-year-old patient with squamous cell carcinoma of the proximal third of the esophagus. He developed a salivatory fistula in the early postoperative period that healed spontaneously. Five months later, the patient developed partial stenosis of the esophagogastric anastomosis which required recervicotomy and excision, after numerous failed dilatation attempts. Eighteen months later, the patient presented to the hospital for severe pain in the upper abdomen. Clinical work-up revealed pericardial perforation by the gastric tube ulcer necessitating emergent surgery and gastric tube removal. We present a patient who developed both early and late complications of subtotal esophagectomy with gastric tube transposition as well as a review of the literature

Annotated List of Ontario Lepidoptera, by J. C. E. Riotte. 1992. Royal Ontario Museum, Publications in Life Sciences, Miscellaneous Publication. Royal Ontario Museum, 100 Queen\u27s Park, Thronto, Ontario, Canada M5S 2C6. 208 pp. Soft cover, 15 x 22.5 cm. ISBN 0-88854-397-2. 19.95Canadian(about19.95 Canadian (about 16.00 U.S.)

(excerpt) I was eager to review this publication. When I was a young person, first starting the pursuit of Lepidoptera, any literature that increased my knowledge was as valuable as the specimens I collected. Checklists were especially welcome. A primary purpose for the formation of The Ohio Lepidopterists society was to record the occurrence of Lepidoptera in Ohio. My ardent commitment to document Ohio\u27s fauna over the past 20 years gives me insight into the work necessary to create and produce a publication of this type

The Araucaria Project. First Cepheid Distance to the Sculptor Group Galaxy NGC 7793 from Variables discovered in a Wide-Field Imaging Survey

We have detected, for the first time, Cepheid variables in the Sculptor Group spiral galaxy NGC 7793. From wide-field images obtained in the optical V and I bands on 56 nights in 2003-2005, we have discovered 17 long-period (24-62 days) Cepheids whose periods and mean magnitudes define tight period-luminosity relations. We use the (V-I) Wesenheit index to determine a reddening-free true distance modulus to NGC 7793 of 27.68 ± 0.05 mag (internal error) ± 0.08 mag (systematic error). The comparison of the reddened distance moduli in V and I with the one derived from the Wesenheit magnitude indicates that the Cepheids in NGC 7793 are affected by an average total reddening of E(B-V)=0.08 mag, 0.06 of which is produced inside the host galaxy. As in the earlier Cepheid studies of the Araucaria Project, the reported distance is tied to an assumed LMC distance modulus of 18.50. The quoted systematic uncertainty takes into account effects like blending and possible inhomogeneous filling of the Cepheid instability strip on the derived distance. The reported distance value does not depend on the (unknown) metallicity of the Cepheids according to recent theoretical and empirical results. Our Cepheid distance is shorter, but within the errors consistent with the distance to NGC 7793 determined earlier with the TRGB and Tully-Fisher methods.The NGC 7793 distance of 3.4 Mpc is almost identical to the one our project had found from Cepheid variables for NGC 247, another spiral member of the Sculptor Group located close to NGC 7793 on the sky. Two other conspicuous spiral galaxies in the Sculptor Group, NGC 55 and NGC 300, are much nearer (1.9 Mpc), confirming the picture of a very elongated structure of the Sculptor Group in the line of sight put forward by Jerjen et al. and others

Panel: Restrictions on Freedom of Association Through Material Support Prohibitions and Visa Denials

In the 1950s, we were afraid of communism. We were afraid, in particular, of the Soviet Union, the world\u27s second greatest superpower, which was armed with masses of nuclear warheads aimed at all our largest cities. As a result, we fought the Cold War, engaged in espionage, proxy wars, and an arms race. We also took aggressive preventive measures at home. The principal preventive measure of that period was guilt by association. We made it a crime to be a member of the Communist Party, and we created a whole administrative scheme to implement and enforce this notion of guilt by association. Today, the threat is terrorism, not communism. And as a doctrinal matter at least, guilt by association is barred by the First and Fifth Amendments. But we nonetheless see a remarkably similar reaction in place. Instead of targeting association expressly, the government targets material support for terrorist organizations. But the essential features of this prohibition are the same. The government employs an extremely broad criminal substantive standard--material support--which encompasses any activity in association with a group classified as a terrorist organization. Giving the organization money is the most obvious example of material support, but even the volunteering of one\u27s time also constitutes material support