Weakly electric fishes have been an important model system in behavioral neuroscience for more than 40 years. These fishes use a specialized electric organ to produce an electric field that is ...typically below 1 volt/cm and serves in many behaviors including social communication and prey detection. Electrical behaviors are easy to study because inexpensive and widely available tools enable continuous monitoring of the electric field of individual or groups of interacting fish. Weakly electric fish have been routinely used in tightly controlled neurophysiological experiments in which the animal is immobilized using neuromuscular blockers (e.g., curare). Although experiments that involve immobilization are generally discouraged because it eliminates movement-based behavioral signs of pain and distress, many observable electrosensory behaviors in fish persist when the animal is immobilized. Weakly electric fish thus offer a unique opportunity to assess the effects of immobilization on behaviors including those that may reflect pain and distress. We investigated the effects of both immobilization and restraint on a variety of electrosensory behaviors in four species of weakly electric fishes and observed minor effects that were not consistent between the species tested or between particular behaviors. In general, we observed small increases and decreases in response magnitude to particular electrosensory stimuli. Stressful events such as asphyxiation and handling, however, resulted in significant changes in the fishes' electrosensory behaviors. Signs of pain and distress include marked reductions in responses to electrosensory stimuli, inconsistent responses, and reductions in or complete cessation of the autogenous electric field.
The determination of the grape variety of aged red wines based on the ratio of acetylated and coumaroylated anthocyanins (
R
ac/coum) can be influenced by the formation of pyranoanthocyanins. ...Coelution of the pyranoanthocyanin pinotin A and the 3-coumaroylglucoside of malvidin can affect the obtained data for the
R
ac/coum values, which in turn could lead to a false classification of wine variety and rejection of the wines by the food authorities. Investigations using different reversed phase high performance liquid chromatography columns demonstrate the importance of a good chromatographic resolution of these analytes.
Context. Star formation at earlier cosmological times took place in an interstellar medium with low metallicity. The Large Magellanic Cloud (LMC) is ideally suited to study star formation in such an ...environment. Aims. The physical and chemical state of the ISM in a star forming environment can be constrained by observations of submm and FIR spectral lines of the main carbon carrying species, CO, C I and C II, which originate in the surface layers of molecular clouds illuminated by the UV radiation of the newly formed, young stars. Methods. We present high-angular resolution sub- millimeter observations in the N159W region in the LMC obtained with the NANTEN2 telescope of the super(12) CO J = 4 \to 3, J = 7 \to 6, and super(13) CO J = 4 \to 3 rotational and C I super(3) P sub(1)- super(3) P sub(0) and super(3) P sub(2)- super(3) P sub(1) fine-structure transitions. The super(13) CO J = 4 \to 3 and C I super(3) P sub(2)- super(3) P sub(1) transitions are detected for the first time in the LMC. We derive the physical and chemical properties of the low-metallicity molecular gas using an escape probability code and a self-consistent solution of the chemistry and thermal balance of the gas in the framework of a clumpy cloud PDR model. Results. The separate excitation analysis of the submm CO lines and the carbon fine structure lines shows that the emitting gas in the N159W region has temperatures of about 80 K and densities of about 10 super(4) cm super(-3). The estimated C to CO abundance ratio close to unity is substantially higher than in dense massive star-forming regions in the Milky Way. The analysis of all observed lines together, including the C II line intensity reported in the literature, in the context of a clumpy cloud PDR model constrains the UV intensity to about \chi \approx 220 and an average density of the clump ensemble of about 10 super(5) cm super(-3), thus confirming the presence of high density material in the LMC N159W region.
Photon dominated regions in NGC 3603 Röllig, M.; Kramer, C.; Rajbahak, C. ...
Astronomy and astrophysics (Berlin),
01/2011, Letnik:
525
Journal Article
Recenzirano
Odprti dostop
Aims. We aim at deriving the excitation conditions of the interstellar gas as well as the local FUV intensities in the molecular cloud surrounding NGC 3603 to get a coherent picture of how the gas is ...energized by the central stars. Methods. The NANTEN2-4 m submillimeter antenna is used to map the CI 1–0, 2–1 and CO 4–3, 7–6 lines in a 2′ × 2′ region around the young OB cluster NGC 3603 YC. These data are combined with C18O 2–1 data, HIRES-processed IRAS 60 μm and 100 μm maps of the FIR continuum, and Spitzer/IRAC maps. Results. The NANTEN2 observations show the presence of two molecular clumps located south-east and south-west of the cluster and confirm the overall structure already found by previous CS and C18O observations. We find a slight position offset of the peak intensity of CO and CI, and the atomic carbon appears to be further extended compared to the molecular material. We used the HIRES far-infrared dust data to derive a map of the FUV field heating the dust. We constrain the FUV field to values of χ = 3−6 × 103 in units of the Draine field across the clouds. Approximately 0.2 to 0.3% of the total FUV energy is re-emitted in the CII 158 μm cooling line observed by ISO. Applying LTE and escape probability calculations, we derive temperatures (TMM1 = 43 K, TMM2 = 47 K), column densities (NMM1 = 0.9 × 1022 cm-2, NMM2 = 2.5 × 1022 cm-2) and densities (nMM1 = 3 × 103 cm-3, nMM2 = 103−104 cm-3) for the two observed molecular clumps MM1 and MM2. Conclusions. The cluster is strongly interacting with the ambient molecular cloud, governing its structure and physical conditions. A stability analysis shows the existence of gravitationally collapsing gas clumps which should lead to star formation. Embedded IR sources have already been observed in the outskirts of the molecular cloud and seem to support our conclusions.
Context. Studying molecular gas in the central regions of the star burst galaxies NGC 4945 and Circinus enables us to characterize the physical conditions and compare them to previous local and ...high-z studies. Aims.We estimate temperature, molecular density and column densities of CO and atomic carbon. Using model predictions we give a range of estimated CO/C abundance ratios. Methods.Using the new NANTEN2 4 m sub-millimeter telescope in Pampa La Bola, Chile, we observed for the first time CO 4–3 and $\ion{C}{i}$ $\rm ^3P_1{-}^3P_0$ at the centers of both galaxies at linear scale of 682 pc and 732 pc respectively. We compute the cooling curves of 12CO and 13CO using radiative transfer models and estimate the physical conditions of CO and CI. Results.The centers of NGC 4945 and Circinus are very $\ion{C}{i}$ bright objects, exhibiting $\ion{C}{i}$ $\rm ^3P_1{-}^3P_0$ luminosities of 91 and 67 K km s-1 kpc2, respectively. The $\ion{C}{i}$ $\rm ^3P_1{-}^3P_0$/CO 4–3 ratio of integrated intensities are large at 1.2 in NGC 4945 and 2.8 in Circinus. Combining previous CO $J= 1{-}0$, 2–1 and 3–2 and 13CO $J= 1{-}0$, 2–1 studies with our new observations, the radiative transfer calculations give a range of densities, $n(\rm H_{2})=10^{3}{-}3 \times 10^{4}$ cm-3, and a wide range of kinetic temperatures, $T_{\rm kin}= 20{-}100$ K, depending on the density. To discuss the degeneracy in density and temperature, we study two representative solutions. In both galaxies the estimated total CI cooling intensity is stronger by factors of ~$1{-}3$ compared to the total CO cooling intensity. The CO/C abundance ratios are 0.2-2, similar to values found in Galactic translucent clouds. Conclusions.Our new observations enable us to further constrain the excitation conditions and estimate the line emission of higher-J CO- and the upper CI-lines. For the first time we give estimates for the CO/C abundance ratio in the center regions of these galaxies. Future CO $J= 7{-}6$ and CI 2–1 observations will be important to resolve the ambiguity in the physical conditions and confirm the model predictions.
PDF
