Zur Theorie des Condensators

Selbstrezension Gustav R. Kirchhoffs zu seinem Aufsatz: Zur Theorie des Condensators In: Monatsberichte der Königlich Preußischen Akademie der Wissenschafte zu Berlin. 1877, S. 144-16

Ueber Reflexion und Brechung des Lichtes an der Grenze krystallinischer Mittel

Selbstrezension Gustav R. Kirchhoffs zu seinem Aufsatz: Ueber Reflexion und Brechung des Lichtes an der Grenze krystallinischer Mittel In: Abhandlungen der Königlichen Akademie der Wissenschaften zu Berlin. Phys. Abth. 2. 1876, S. 57-8

High-Precision Entropy Values for Spanning Trees in Lattices

Shrock and Wu have given numerical values for the exponential growth rate of the number of spanning trees in Euclidean lattices. We give a new technique for numerical evaluation that gives much more precise values, together with rigorous bounds on the accuracy. In particular, the new values resolve one of their questions.Comment: 7 pages. Revision mentions alternative approach. Title changed slightly. 2nd revision corrects first displayed equatio

Equatorial ozone characteristics as measured at Natal (5.9 deg S, 35.2 deg W)

Ozone density profiles obtained through electrochemical concentration cell (ECC) sonde measurements at Natal were analyzed. Time variations, as expected, are small. Outstanding features of the data are tropospheric densities substantially higher than those measured at other stations, and also a total ozone content that is higher than the averages given by satellite measurements

P2X1 and P2X5 subunits form the functional P2X receptor in mouse cortical astrocytes

ATP plays an important role in signal transduction between neuronal and glial circuits and within glial networks. Here we describe currents activated by ATP in astrocytes acutely isolated from cortical brain slices by non-enzymatic mechanical dissociation. Brain slices were prepared from transgenic mice that express enhanced green fluorescent protein under the control of the human glial fibrillary acidic protein promoter. Astrocytes were studied by whole-cell voltage clamp. Exogenous ATP evoked inward currents in 75 of 81 astrocytes. In the majority (~65%) of cells, ATP-induced responses comprising a fast and delayed component; in the remaining subpopulation of astrocytes, ATP triggered a smoother response with rapid peak and slowly decaying plateau phase. The fast component of the response was sensitive to low concentrations of ATP (with EC50 of ~40 nM). All ATP-induced currents were blocked by pyridoxal-phosphate-6-azophenyl-2',4'-disulfonate (PPADS); they were insensitive to ivermectin. Quantitative real-time PCR demonstrated strong expression of P2X1 and P2X5 receptor subunits and some expression of P2X2 subunit mRNAs. The main properties of the ATP-induced response in cortical astrocytes (high sensitivity to ATP, biphasic kinetics, and sensitivity to PPADS) were very similar to those reported for P2X1/5 heteromeric receptors studied previously in heterologous expression systems

An Injectable Trace Mineral Supplement in Yearling Bulls Causes a Short-Term Increase in Circulating Trace Mineral Levels But Does Not Improve Sperm Quality

Proper trace mineral supplementation is necessary for reproductive development and function. Supplementation with various trace minerals has been shown to improve overall sperm quality and morphology and increase the percentage of live sperm. When developing beef bulls, it is necessary to meet trace mineral requirements to ensure proper reproductive success. An injectable trace mineral product has been made commercially available for use in cattle as a supplemental form of chelated selenium, copper, zinc, and manganese. Considering the role of trace minerals in bull reproductive function, we posed the question of whether using an injectable trace mineral product beyond dietary supplementation could improve sperm quality and percentage of bulls passing yearling breeding soundness exams. The objectives of our study were to compare serum trace mineral concentrations of bulls before and after administration of an injection of trace minerals or saline and to compare semen trace mineral concentrations after treatment. To determine if an injectable trace mineral product could be of benefit, we compared serum and semen trace mineral concentrations as well as semen quality and percentage passing a yearling breeding soundness examination in treated and untreated bulls

Generalized vortex-model for the inverse cascade of two-dimensional turbulence

We generalize Kirchhoff's point vortex model of two-dimensional fluid motion to a rotor model which exhibits an inverse cascade by the formation of rotor clusters. A rotor is composed of two vortices with like-signed circulations glued together by an overdamped spring. The model is motivated by a treatment of the vorticity equation representing the vorticity field as a superposition of vortices with elliptic Gaussian shapes of variable widths, augmented by a suitable forcing mechanism. The rotor model opens up the way to discuss the energy transport in the inverse cascade on the basis of dynamical systems theory.Comment: 14 pages, 21 figure

Chrysanthemum species used as food and medicine: Understanding quality differences on the global market

Background Chrysanthemum flowers [Ch. x morifolium (Ramat.) Hemsl. and Ch. indicum L.] are a globally used and pharmacologically interesting botanical drug, however, with variable product quality. Objective We aim at understanding the chemical variability of primary material available commercially based on different origins and associated quality problems like contamination with heavy metals. This needs to be assessed in the context of the current regulations for this botanical drug and associated problems. Material and Methods 15 C. indicum L. and 50 C. x morifolium (Ramat.) Hemsl., including a range of geographical cultivars recognized in China, samples from the USA, Europe and China were analyzed using High Performance Thin Layer Chromatography (HPTLC) to compare their general chemical profile. Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) was used to quantify heavy metal contamination. Results The: HPTLC fingerprints of C. indicum samples are clearly distinguishable from C. x morifolium. Fingerprints of samples from the same cultivars collected from markets in different countries (USA and China) show different patterns. Large variance of fingerprints within each cultivar group was observed. The heavy metal analysis showed excessive amounts of some harmful heavy metal in some commercial products with excessive cadmium being the most frequent problem. Conclusions The Chinese medicinal cultivars vary. Differences between samples sourced from the USA and China might be ascribable to geographical factors (e.g. soil composition), degradation during transport/storage or adulteration, but geographical differences should also be taken into account. Importantly, a much more detailed definition of the drug are needed for better quality control. In addition, with continuous contamination problem observed, a more widespread regulation is an essential requirement for better quality

Beiträge zu den Verhandlungen des naturhistorisch-medicinischen Vereins zu Heidelberg

Inhalt: Band 1, 1857 bis 1859 - Ueber das Sonnenspektrum Band 2, 1858 bis 1862 - Ueber einen neuen Satz der Wärmelehre - Demonstration des Ruhmkorff'schen Apparats - Ueber Rubidium und Caesium / Vortrag von Robert W. Bunsen - Ueber den von Herrn Hofr. Bunsen und ihm construirten Spektral-Apparat Band 3, Dez. 1862 bis März 1865 - Ueber die Beobachtungen von Miller und Huggins über die Spektra der Gestirn