Gattungen und Arten der Schwämme

Enthält: [Hauptbd.] Accedvnt Icones LVII Fvngorvm Nonnvllorvm Agri Jenensis, Secvndvm Natvram Ab Avtore Depictae; Aeri Incisae Et Vivis Coloribvs Fvcatae a I. S. Capievx = Nebst 57 vom Verfasser nach der Natur gemahlten und von Herrn Capieux gestochenen und illuminirten Abbildungen einiger Schwämme aus der Gegend von Jena, 1783 1. Continuatio prima Describens CXXV Species Et Varietates Totidem Iconibus LIX - CLXXXIII Repraesentatas, 1786 2. Continuatio secunda Describens XLIX. Species et Varietates, Totidem Iconibus CLXXXIV - CCXXXII. Repraesentatas, 178

Feedback control architecture & the bacterial chemotaxis network

Bacteria move towards favourable and away from toxic environments by changing their swimming pattern. This response is regulated by the chemotaxis signalling pathway, which has an important feature: it uses feedback to ‘reset’ (adapt) the bacterial sensing ability, which allows the bacteria to sense a range of background environmental changes. The role of this feedback has been studied extensively in the simple chemotaxis pathway of Escherichia coli. However it has been recently found that the majority of bacteria have multiple chemotaxis homologues of the E. coli proteins, resulting in more complex pathways. In this paper we investigate the configuration and role of feedback in Rhodobacter sphaeroides, a bacterium containing multiple homologues of the chemotaxis proteins found in E. coli. Multiple proteins could produce different possible feedback configurations, each having different chemotactic performance qualities and levels of robustness to variations and uncertainties in biological parameters and to intracellular noise. We develop four models corresponding to different feedback configurations. Using a series of carefully designed experiments we discriminate between these models and invalidate three of them. When these models are examined in terms of robustness to noise and parametric uncertainties, we find that the non-invalidated model is superior to the others. Moreover, it has a ‘cascade control’ feedback architecture which is used extensively in engineering to improve system performance, including robustness. Given that the majority of bacteria are known to have multiple chemotaxis pathways, in this paper we show that some feedback architectures allow them to have better performance than others. In particular, cascade control may be an important feature in achieving robust functionality in more complex signalling pathways and in improving their performance

How Does Casimir Energy Fall?

Doubt continues to linger over the reality of quantum vacuum energy. There is some question whether fluctuating fields gravitate at all, or do so anomalously. Here we show that for the simple case of parallel conducting plates, the associated Casimir energy gravitates just as required by the equivalence principle, and that therefore the inertial and gravitational masses of a system possessing Casimir energy $E_c$ are both $E_c/c^2$. This simple result disproves recent claims in the literature. We clarify some pitfalls in the calculation that can lead to spurious dependences on coordinate system.Comment: 5 pages, 1 figure, REVTeX. Minor revisions, including changes in reference

The nature of the dense core population in the pipe nebula: core and cloud kinematics from C18O observations

We present molecular-line observations of 94 dark cloud cores identified in the Pipe nebula through near-IR extinction mapping. Using the Arizona Radio Observatory 12m telescope, we obtained spectra of these cores in the J=1-0 transition of C18O. We use the measured core parameters, i.e., antenna temperature, linewidth, radial velocity, radius and mass, to explore the internal kinematics of these cores as well as their radial motions through the larger molecular cloud. We find that the vast majority of the dark extinction cores are true cloud cores rather than the superposition of unrelated filaments. While we identify no significant correlations between the core's internal gas motions and the cores' other physical parameters, we identify spatially correlated radial velocity variations that outline two main kinematic components of the cloud. The largest is a 15pc long filament that is surprisingly narrow both in spatial dimensions and in radial velocity. Beginning in the Stem of the Pipe, this filament displays uniformly small C18O linewidths (dv~0.4kms-1) as well as core to core motions only slightly in excess of the gas sound speed. The second component outlines what appears to be part of a large (2pc; 1000 solar mass) ring-like structure. Cores associated with this component display both larger linewidths and core to core motions than in the main cloud. The Pipe Molecular Ring may represent a primordial structure related to the formation of this cloud.Comment: Accepted to ApJ. 14 pages, 11 figures. Complete table at end of documen

A study of bacteria in bovine semen and their effect upon livability of spermatozoa

Digitized 2007 AES.Includes bibliographical references (pages 11-12)

FLAMINGOS Spectroscopy of New Low-Mass Members of the Young Cluster IC 348

We present spectroscopy of candidate stellar and substellar members of the young cluster IC 348. Using the Florida Multi-Object Imaging Near-Infrared Grism Observational Spectrometer with the 4 meter telescope at Kitt Peak National Observatory, we have obtained multi-object moderate-resolution (R=1000) J- and H-band spectra of 66 infrared sources (H=12-17) toward IC 348, many of which are difficult to observe spectroscopically at optical wavelengths (I>20) because they are highly reddened and/or intrinsically cool and red. We have also observed 19 known cluster members that have optical spectral types available from previous work. By using these latter sources as the spectral classification standards, we have identified 14 new members of the cluster with types of M2-M6 in the sample of 66 new objects. Two additional objects exhibit types of >M8.5, but cannot be conclusively classified as either field dwarfs or cluster members with available data. We have estimated extinctions, luminosities, and effective temperatures for these 16 M-type objects, placed them on the H-R diagram, and used the evolutionary models of Chabrier & Baraffe to estimate their masses. If the two candidates at >M8.5 are indeed members, they should be among the least massive known brown dwarfs in IC 348 (M/M_sun~0.01).Comment: 15 pages, The Astrophysical Journal, 2004, v618 (January 10