Total and partial cloud amount detection during summer 2005 at Westerland (Sylt, Germany)

The detection of cloudiness is investigated by means of partial and total cloud amount estimations from pyrgeometer radiation measurements and visible all-sky imager observations. The measurements have been performed in Westerland, a seaside resort on the North Sea island of Sylt, Germany, during summer 2005. An improvement to previous studies on this subject resulting in the first time partial cloud amounts (PCAs), defined as cloud amounts without high clouds calculated from longwave downward radiation (LDR) according to the APCADA algorithm (Dürr and Philipona, 2004), are validated against both human observations from the National Meteorological Servive DWD at the nearby airport of Sylt and digital all-sky imaging. The aim is to establish the APCADA scheme at a coastal midlatitude site for longterm observations of cloud cover and to quantify errors resulting from the different methods of detecting cloudiness. Differences between the resulting total cloud amounts (TCAs), defined as cloud amount for all-cloud situations, derived from the camera images and from human observations are within ±1 octa in 72% and within ±2 octa in 85% of the cases. Compared to human observations, PCA measurements, according to APCADA, underestimate the observed cloud cover in 47% of all cases and the differences are within ±1 octa in 60% and ±2 octa in 74% of all cases. Since high cirrus clouds can not be derived from LDR, separate comparisons for all cases without high clouds have been performed showing an agreement within ±1(2) octa in 73(90)% for PCA and also for camera-derived TCA. For this coastal mid-latitude site under investigation, we find similar though slightly smaller agreements to human observations as reported by Dürr and Philipona (2004). Though limited to daytime, the cloud cover retrievals from the sky imager are not really affected by cirrus clouds and provide a more reliable cloud climatology for all-cloud conditions than APCADA

Episode of unusual high solar ultraviolet radiation over central Europe due to dynamical reduced total ozone in May 2005

In late May 2005 unusual high levels of solar ultraviolet radiation were observed over central Europe. In Northern Germany the measured irradiance of erythemally effective radiation exceeded the climatological mean by more than about 20%. An extreme low ozone event for the season coincided with high solar elevation angles and high pressure induced clear sky conditions leading to the highest value of erythemal UV-radiation ever observed over this location in May since 1994. This hereafter called "ozone mini-hole" was caused by an elevation of tropopause height accompanied with a poleward advection of ozone-poor air from the tropics. The resultant increase in UV-radiation is of particular significance for human health. Dynamically induced low ozone episodes that happen in late spring can considerably enhance the solar UV-radiation in mid latitudes and therefore contribute to the UV-burden of people living in these regions

The Influence of Installed Technologies on Future Adoption Decisions: Empirical Evidence from E-Business

This paper studies the adoption times of various e-business technologies in a large sample of firms from 10 different industry sectors and 25 European countries between 1994 and 2002. The results show that the probability of adoption increases with the number of previously adopted e-business technologies. Hence, the more advanced a firm is in using e-business technologies, the more likely it is to adopt additional e-business technologies, provided technologies do not substitute each other in their functionalities. This result is relevant for the marketing of new technologies, strategic planning and, from an economic perspective, for the convergence of growth across regions

Acceleration of Technology Adoption withing Firms

This paper studies the diffusion of multiple, related technologies among firms. The results suggest an endogenous acceleration mechanism of technology adoption: The more advanced a firm is in using a particular set of technologies, the more likely it is to adopt additional, related technologies. We show that such a mechanism can occur under fairly general circumstances. If firms are not ex ante identical, the endogenous acceleration mechanism suggests a growing divergence in technological endowment of firms in the early phases after the emergence of a new technological paradigm. The theoretical predictions are tested with a dataset that records the adoption times of various e-business technologies in a large sample of firms from 10 different industry sectors and 25 European countries. The results show that the probability to adopt strictly increases with the number of previously adopted e-business technologies. Evidence for a growing digital divide among the companies in the sample is demonstrated for the period from 1994-2002

Acceleration of technology adoption within firms -- Emperical evidence from e-business

This paper studies the diffusion of multiple related technologies among firms. The results suggest an endogenous acceleration mechanism for technology adoption: The more advanced a firm is in using a particular set of technologies, the more likely it is to adopt additional related technologies. We show that such a mechanism can occur under fairly general circumstances. If firms are not ex ante identical, the endogenous acceleration mechanism suggests a growing divergence in the technological endowment of firms in the early phases after the emergence of a new technological paradigm. The theoretical predictions are tested with a dataset that records the adoption times of various e- business technologies in a large sample of firms from 10 different industry sectors and 25 European countries. The results show that the probability of adoption increases with the number of previously adopted e-business technologies. Evidence for a growing digital divide among the companies in the sample is demonstrated for the period from 1994-2002

Infrared study of the charge-ordered multiferroic LuFe(2)O(4)

The reflectivity of a large LuFe(2)O(4) single crystal has been measured with the radiation field either perpendicular or parallel to the c axis of its rhombohedral structure, from 10 to 500K, and from 7 to 16000 cm-1. The transition between the two-dimensional and the three-dimensional charge order at T_(CO) = 320 K is found to change dramatically the phonon spectrum in both polarizations. The number of the observed modes above and below T_(CO), according to a factor-group analysis, is in good agreement with a transition from the rhombohedral space group R{bar 3}m to the monoclinic C2/m. In the sub-THz region a peak becomes evident at low temperature, whose origin is discussed in relation with previous experiments.Comment: Physical Review B in pres

Paper Session II-C - Pegasus and Taurus Launch Vehicles

The Pegasus Air-Launched Space Booster is an innovative new space launch vehicle now in full scale development and initial production. Pegasus, developed by a privately-funded joint venture of Orbital Sciences Corporation (OSC) and Hercules Aerospace Company, is a three-stage, solid-propellant, inertially-guided, winged vehicle that is launched from a carrier aircraft at 40,000 ft and Mach .8. This 50 ft long, 41,000 Ib vehicle can deliver a payload of 900 Ib into a low inclination, 150 nmi Earth orbit. The first two Pegasus flights are sponsored by the Defense Advanced Research Projects Agency (DARPA), with additional missions currently reserved by the U.S. Air Force and commercial customers. Pegasus was conceived to provide a more flexible and more efficient launch system for small space payloads by taking advantage of the many benefits inherent in the airborne launch approach. The Pegasus system achieves a substantial improvement in payload performance relative to comparable ground-based launch vehicle designs, while also providing numerous advantages in operational flexibility and cost effectiveness. The flight vehicle, shown in Figure 1, consists of three solid-propellant rocket motors, a fixed highmounted composite delta wing, an aft skirt assembly including three composite fins, an avionics section atop the third stage, and a two-piece composite payload fairing

Catalog of Galaxy Morphology in Four Rich Clusters: Luminosity Evolution of Disk Galaxies at 0.33<z<0.83

Hubble Space Telescope (HST) imaging of four rich, X-ray luminous, galaxy clusters (0.33<z<0.83) is used to produce quantitative morphological measurements for galaxies in their fields. Catalogs of these measurements are presented for 1642 galaxies brighter than F814W(AB)=23.0 . Galaxy luminosity profiles are fitted with three models: exponential disk, de Vaucouleurs bulge, and a disk-plus-bulge hybrid model. The best fit is selected and produces a quantitative assessment of the morphology of each galaxy: the principal parameters derived being B/T, the ratio of bulge to total luminosity, the scale lengths and half-light radii, axial ratios, position angles and surface brightnesses of each component. Cluster membership is determined using a statistical correction for field galaxy contamination, and a mass normalization factor (mass within boundaries of the observed fields) is derived for each cluster. In the present paper, this catalog of measurements is used to investigate the luminosity evolution of disk galaxies in the rich-cluster environment. Examination of the relations between disk scale-length and central surface brightness suggests, under the assumption that these clusters represent a family who share a common evolutionary history and are simply observed at different ages, that there is a dramatic change in the properties of the small disks (h < 2 kpc). This change is best characterized as a change in surface brightness by about 1.5 magnitude between z=0.3 and z=0.8 with brighter disks at higher redshifts.Comment: 53 pages, including 13 figures and 7 tables. Accepted for publication in the Astrophysical Journal Supplement Serie

Accuracy of computerized tomography in determining hepatic tumor size in patients receiving liver transplantation or resection

Computerized tomography (CT) of liver is used in oncologic practice for staging tumors, evaluating response to treatment, and screening patients for hepatic resection. Because of the impact of CT liver scan on major treatment decisions, it is important to assess its accuracy. Patients undergoing liver transplantation or resection provide a unique opportunity to test the accuracy of hepatic-imaging techniques by comparison of finding of preoperative CT scan with those at gross pathologic examination of resected specimens. Forty-one patients who had partial hepatic resection (34 patients) or liver transplantation (eight patients) for malignant (30 patients) or benign (11 patients) tumors were evaluable. Eight (47%) of 17 patients with primary malignant liver tumors, four (31%) of 13 patients with metastatic liver tumors, and two (20%) of 10 patients with benign liver tumors had tumor nodules in resected specimens that were not apparent on preoperative CT studies. These nodules varied in size from 0.1 to 1.6 cm. While 11 of 14 of these nodules were 1.0 cm. These results suggest that conventional CT alone may be insufficient to accurately determine the presence or absence of liver metastases, extent of liver involvement, or response of hepatic metastases to treatment