The detections of atomic hydrogen, heavy atoms and ions surrounding the extrasolar giant planet (EGP) HD209458b constrain the composition, temperature and density profiles in its upper atmosphere. Thus the observations provide guidance for models that have so far predicted a range of possible conditions. We present the first hydrodynamic escape model for the upper atmosphere that includes all of the detected species in order to explain their presence at high altitudes, and to further constrain the temperature and velocity profiles. This model calculates the stellar heating rates based on recent estimates of photoelectron heating efficiencies, and includes the photochemistry of heavy atoms and ions in addition to hydrogen and helium.The composition at the lower boundary of the escape model is constrained * Corresponding author. Faxby a full photochemical model of the lower atmosphere. We confirm that molecules dissociate near the 1 µbar level, and find that complex molecular chemistry does not need to be included above this level. We also confirm that diffusive separation of the detected species does not occur because the heavy atoms and ions collide frequently with the rapidly escaping H and H + . This means that the abundance of the heavy atoms and ions in the thermosphere simply depends on the elemental abundances and ionization rates. We show that, as expected, H and O remain mostly neutral up to at least 3 R p , whereas both C and Si are mostly ionized at significantly lower altitudes. We also explore the temperature and velocity profiles, and find that the outflow speed and the temperature gradients depend strongly on the assumed heating efficiencies. Our models predict an upper limit of 8,000 K for the mean (pressure averaged) temperature below 3 R p , with a typical value of 7,000 K based on the average solar XUV flux at 0.047 AU. We use these temperature limits and the observations to evaluate the role of stellar energy in heating the upper atmosphere.

A nonlinear spectral gravity wave (GW) drag parameterization systematically accounting for breaking and dissipation in the thermosphere developed by Yiğit et al. (2008) has been implemented into the University College London Coupled Middle Atmosphere‐Thermosphere‐2 (CMAT2) general circulation model (GCM). The dynamical role of GWs propagating upward from the lower atmosphere has been studied in a series of GCM tests for June solstice conditions. The results suggest that GW drag is not only nonnegligible above the turbopause, but that GWs propagate strongly into the upper thermosphere, and, upon their dissipation, deposit momentum comparable to that of ion drag, at least up to 180–200 km. The effects of thermospheric GW drag are particularly noticeable in the winter (southern) hemisphere, where weaker westerlies and stronger high‐latitude easterlies are simulated well, in agreement with the empirical Horizontal Wind Model (HWM93). The dynamic response in the F region is sensitive to the variations of the source spectrum. However, the spectra commonly employed in middle atmosphere GCMs reproduce the circulation both in the lower and upper thermosphere reasonably well.

3Pathology and 4Surgery, Christie and Withington Hospitals, Manchester M20 9BX, UK.Summary The aim of this study was to determine the proliferative activity within the epithelial cells of the normal human breast in 122 patients (6 reduction mammoplasties and 116 fibroadenoma excisions) in relation to age and the phase of the menstrual cycle. Thirty three of the patients were on oral contraceptives and 33 were parous.Thin tissue slices were incubated with tritiated thymidine and processed for autoradiography. Other samples were fixed directly and prepared for histology. The labelling, mitotic and apoptotic indices (LI, MI and Al) were determined and all illustrated considerable variability. The labelling indices are significantly (P<0.05) influenced by both patient age and stage during the menstrual cycle and ranged from 0-11.5%. Maximum LI values were obtained on the 20.8th day of the cycle. A square root transformation of the data was used to reduce the skewness of the data to a more normal distribution. The square root of the LI declined by 0.22 per decade. The mitotic data showed similar significant (P<0.05) correlations against age and day of cycle with a peak on the 21.5th day of the cycle, a decline by 0.072 per decade and a range from 0-0.6%. The data for apoptotic cells were less clearly influenced by the stage of the menstrual cycle but showed a significant (P<0.5) decline with age. The Al in parous patients was significantly higher than that in non-parous patients. There was no significant effect of oral contraceptives on any of the parameters measured when age and stage of cycle were taken into account. The considerable variability in the data could not be fully accounted for by either technical factors, the age of the patients, or the day of the cycle.We conclude that proliferation is negatively related to age and is influenced by the menstrual cycle but that additional as yet unknown factors must account for a large part of the variability seen in the data.Events which occur early in reproductive life, such as exposure to ionising radiation or an early menarche, are known to be related to the subsequent development of malignant neoplasms of the breast (Land et al., 1980, MacMahon et al., 1973. The breast may be susceptable during this period because of a high rate of cellular proliferation and because carcinogenic agents may act preferentially upon proliferating tissues (Russo et al., , 1987. However there are few data concerning the association between age and proliferative activity of the normal human breast (Anderson et al., 1982, Meyer, 1977Russo et al., 1987) and one aim of this study was to investigate this relationship further.Oestrogen is a major growth promoting hormone of the breast: under some circumstances progesterone acts as an antioestrogen and appears to inhibit proliferation (MauvaisJarvis et al., 1986). On the basis of these observations Korenman (1980) proposed that the risk of breast cancer was related to a defective luteal phase with low or absent progesterone secretion. Women w...

The type VI secretion system (T6SS) is a multi-protein complex that injects bacterial effector proteins into target cells. It is composed of a cell membrane complex anchored to a contractile bacteriophage tail-like apparatus consisting of a sharpened tube that is ejected by the contraction of a sheath against a baseplate. We present structural and biochemical studies on TssA subunits from two different T6SSs that reveal radically different quaternary structures in comparison to the dodecameric E. coli TssA that arise from differences in their C-terminal sequences. Despite this, the different TssAs retain equivalent interactions with other components of the complex and position their highly conserved N-terminal ImpA_N domain at the same radius from the centre of the sheath as a result of their distinct domain architectures, which includes additional spacer domains and highly mobile interdomain linkers. Together, these variations allow these distinct TssAs to perform a similar function in the complex.

Transits in the H I 1216Å (Lyman α), O I 1334Å, C II 1335Å, and Si III 1206.5Å lines constrain the properties of the upper atmosphere ofHD209458b. In addition to probing the temperature and density profiles in the thermosphere, they have implications for the properties of the lower atmosphere. Fits to the observations with a simple empirical model and a direct comparison with a more complex hydrodynamic model constrain the mean temperature and ionization state of the atmosphere, and imply that the optical depth of the extended thermosphere of the planet in the atomic resonance lines is significant. In particular, it is sufficient to explain the observed transit depths in the H I 1216Å line. The detection of O at high altitudes implies that the minimum mass loss rate from the planet is approximately 6 × 10 6 kg s −1 . The mass loss rate based on our model is higher than this and implies that diffusive separation is prevented for neutral species with a mass lower than about 130 amu by the escape of H. Heavy ions are transported to the upper atmosphere by Coulomb collisions with H + and their presence does not provide as strong constraints on the mass loss rate as the detection of heavy neutral atoms. Models of the upper atmosphere with solar composition and heating based on the average solar X-ray and EUV flux agree broadly with the observations but tend to underestimate the transit depths in the O I, C II, and Si III lines. This suggests that the temperature and/or elemental abundances in the thermosphere may be higher than expected from such models. Observations of the escaping atmosphere can potentially be used to constrain the strength of the planetary magnetic field. We find that a magnetic moment of m 0.04 m J , where m J is the Jovian magnetic moment, allows the ions to escape globally rather than only along open field lines. The detection of Si 2+ in the thermosphere indicates that clouds of forsterite and enstatite do not form in the lower atmosphere. This has implications for the temperature and dynamics of the atmosphere that also affect the interpretation of transit and secondary eclipse observations in the visible and infrared wavelengths.The detection of H, O, C + , and Si 2+ in the upper atmosphere of HD209458b 2 (Vidal-Madjar et al., 2003, 2004 Linsky et al., 2010), and the tentative de-3 tection of H in the upper atmosphere of HD189733b (Lecavelier des Etangs 4 et al., 2010) and Mg + in the upper atmosphere of WASP-12b (Fossati et al., 5 2010) are among the most exciting recent discoveries related to the atmo-6 spheres of extrasolar giant planets (EGPs). The observations demonstrate 7 that the the upper atmospheres of close-in EGPs such as HD209458b differ 8 significantly from the thermospheres of the giant planets in the solar system.9They are much hotter, they extend to several planetary radii and instead of 10 molecular hydrogen, they are primarily composed of atoms and atomic ions. 11The detection of heavy atoms and ions such as O, C + , Si 2+ , and Mg + 12 implies that the atmospheres of close...

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Experiments have been performed to examine the effects of activating the carotid body chemoreceptors and the arterial baroreceptors on the discharge of neurones within the hypothalamic supraoptic nucleus of the rat. Chemoreceptors were activated by intracarotid injection of 0.9% NaCl solution equilibrated with 100% CO2. The baroreceptors of the carotid sinus and aortic arch were activated by raising the blood pressure with an intravenous injection of phenylephrine. Chemoreceptor stimulation activated and baroreceptor stimulation inhibited the discharge of all the phasically discharging neurones tested. Neither stimulus had any consistent effect on non-phasically discharging neurones, although slight inhibition occasionally occurred. Anaesthesia of the carotid bifurcation abolished the effects of cardiovascular stimulation on the supraoptic neurones. Responses resumed when the anaesthesia wore off. However, the anaesthesia also seemed to alter the phasic pattern of discharge. The results are discussed with reference to the influence of the cardiovascular receptors upon the neurones in the supraoptic nucleus, and with reference to possible roles for the cardiovascular reflexes in control of vasopressin secretion.

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