Tracer Study of Mixing and Transport in the Upper Hudson River with Multiple Dams

In October 2001, ～ 0.2?mol of SF6 was injected into the upper Hudson River, a modified natural channel with multiple dams, at Ft. Edward, N.Y. The tracer was monitored for 7 days as it moved ～ 50?km downriver. The longitudinal evolution of the tracer distribution was used to estimate one-dimensional advection (9.0±0.2?km?d?1) and dispersion (17.3±4.0?m2?s?1) along the river axis. Comparison of these results to tracer studies on channels without dams suggests that dams reduce longitudinal dispersion below the value expected in a natural channel with the same discharge. SF6 loss through air–water gas exchange along the river and at two dams (10.7?m combined height) was estimated by observing decay in peak concentration. Losses at dams (approximately 50% per dam) were dominant. The estimated gas exchange at dams was compared to a simple model adapted from those available in literature. Small amounts of tracer were trapped in a canal segment ( ～ 5?km long) that parallels the river, where advection and dispersion were sharply reduced.     

The splice-pattern of CD44 is altered in chronic pancreatitis exhibiting dysplastic changes

Recent studies have shown that several splice variants of CD44, might be involved in tumor progression. Since chronic pancreatitis is suggested to be a risk factor for pancreatic cancer we investigated the splice pattern of CD44 in chronic pancreatitis to elucidate the role of CD44 in pancreas tumorigenesis. The expression of CD44-isoforms was examined in 40 specimens of chronic pancreatitis and 12 specimens of normal pancreas by immunohistochemistry, Westernblotting and exon specific RT-PCR. Pancreatic cancer tissue from two patients who developed pancreatic cancer 2 and 3 years following surgery for chronic pancreatitis were analyzed. Strong expression of CD44s was found in all cells, whereas the expression of CD44v6 was restricted to ductal cells. Westernblotting revealed an overexpression of CD44v6 in chronic pancreatitis as compared to normal pancreas. Exon specific analysis revealed an altered splice pattern of CD44, similar to that in pancreatic cancer, in 12.5% of the chronic pancreatitis specimens. Both patients who developed pancreatic cancer after chronic pancreatitis exhibited this altered splice pattern in both, chronic pancreatitis and pancreatic cancer. These results suggest that variant forms of CD44-mRNA might be expressed in early dysplastic alterations in chronic pancreatitis.     

Comparison of SF6 and Fluorescein as Tracers for Measuring Transport Processes in a Large Tidal River

We present the first large-scale comparison of a fluorescent dye [fluorescein (C20H10O5Na2)] and a gas [sulfur hexafluoride (SF6)] as tracers of advection and longitudinal dispersion from a dual tracer release experiment conducted in the tidal Hudson River. At the beginning of the experiment, 36?kg of fluorescein and ～ 4.3?mol of SF6 were injected into the Hudson River at an averaged depth of 9.5?m, ～ 1?m above the bottom, near Hyde Park, N.Y. After injection, fluorescein distributions were surveyed for 4 days (until it became undetectable) and SF6 distributions were surveyed for 10 days. The dye resolves initial vertical mixing on the day of injection, and then net advection and longitudinal dispersion, whereas SF6 provides information on net advection and longitudinal mixing on larger spatial scales and longer time scales. Quantitative estimates of transport processes (net advection and longitudinal dispersion) calculated from the two methods are consistent for the first three days, and start to deviate on the fourth day when the signal-to-noise ratio of the dye deteriorated.     

Produkte zum IT-gestützten Social Networking in Unternehmen

The use of Social Networking Services for private purposes has been increasing considerably in the past few years. In the same time companies started to experiment with such services to support formal and informal communication and networking among their employees. This article gives an overview of services and application for IT-supported Social Networking in companies. First, the authors place Social Networking Services in the context of Web 2.0 and Social Software. Thereupon, they discuss the benefits and the motivation of the deployment of Social Networking Software in companies, and introduce some specific IT solutions. Finally, they also address necessary future developments in the field of Social Networking Services.     

Evolution of nerve development in frogs. I. The development of the peripheral nervous system in Discoglossus pictus (Discoglossidae)

The gross anatomical development of the peripheral nervous system (PNS) during embryogenesis and metamorphosis in the frog Discoglossus pictus is described based on whole-mount immunostaining for nerves and muscles. In the head, neurite outgrowth starts with the mandibular ramus of the trigeminal nerve at the tailbud stage. Cranial muscles are innervated as soon as they differentiate, beginning at mid-embryonic stages. During late embryonic stages, the course of the trigeminal and facial nerves becomes greatly distorted and changes again drastically during metamorphosis accompanying the reorganization of the jaw muscles. Two occipital somites and nerves develop transitorily but degenerate at late embryonic stages. The hypoglossal nerve develops by fusion of the first and second spinal nerves and receives a transitory contribution of the third and fourth spinal nerve at embryonic stages. In the trunk, several classes of Rohon-Beard neurites could be identified at embryonic stages, one of which forms intersegmental sensory nerves that prefigure the course of the sensory rami of spinal nerves at later stages. We give detailed schedules of PNS and cranial muscle development which, in comparison with data on other frog species described in a companion paper, will serve as a basis to evaluate heterochronic shift during evolution of PNS development in frogs.     

Carbon-13 NMR Spectra of Lignins, 10.1 Comparison of Structural Units in Spruce and Beech Lignin

90.7 MHz Carbon-13 NMR spectra of spruce and beech milled wood lignins (MWLs) and comparison with the spectra of their acetates as well as acetylated dehydrogenation polymer (DHP) from coniferyl alcohol reveals detailed information on the constitution of the two lignins. The signals indicative of β-0-4 units are split, due to the occurrence of erythro and threo isomers. In beech lignin erythro β-0-syringyl ethers by far prevail in the β-0-4-linkages. The spectra also provide unequivocal evidence for the occurrence of β-5 and β-β linkages in both spruce and beech lignins, while some anomalies remain in the case of β-1 and α,β-bis-0-4 units. Two-dimensional ¹³C-J(¹H)-NMR spectra of acetylated DHP corroborate the assignment of signals in the spectra of acetylated MWLs.     

Die Fokker‐Planck‐Gleichung zur Beschreibung von axialen Transport‐ und Mischvorgängen in Rohrreaktoren

One way to explain the mechanism of powder mixing is the Fokker‐Planck equation. The equation comprises two decisive parameters, the transport coefficient U that depends on the active transport of the mixing device and the dispersion coefficient D which describes the mobility of the single particles. The idea is to calculate the dispersion and transport coefficient by using the powder characteristics. To verify this assumption, measurements with different components and different rotation speeds were made.     

A study of power quality loss in PV modules caused by wind induced vibration located in Vienna

Mechanical vibrations of a solar module mounting rack cause oscillations in the orientation of the module towards the sun. The resulting intensity oscillations of the incident light generate an a.c. current at the module’s terminals.We have investigated this effect in the laboratory by means of a vibration table and outdoors, where wind forces induce vibrations to the mounting rack. Although the collected results are specific and restricted to our experimental set up and the regional environmental situation we deduce that vibration induced current transients and oscillations of a solar module’s output most often will be the dominant origin of distortion in the low frequency regime.