Neuronal activation in nucleus tractus solitarius and area postrema of young and aged female rats induced by hypotension

It is well documented that blood pressure changes with age, and the effect is particularly pronounced in females. However, few studies have examined blood pressure in aged individuals, and most animal studies have been done with male rats. Our goal was to investigate responses to experimental hypotension in aged females, comparing activity in central nervous system areas implicated in blood pressure control in young and aged female rats. Isoproterenol (ISOP) is a B-adrenergic agonist that produces hypotension, thereby activating the renin-angiotensin system (RAS) and baroreceptors located in the aorta and great veins. Input from baroreceptors terminates in the hindbrain Nucleus of the Solitary Tract (NTS), whereas circulating hormones are detected by the adjacent Area Postrema (AP). Accordingly, we assessed neural activation in these areas using immunohistochemical labeling for the fos protein.The results showed a marked difference in numbers of fos+ neurons between young and aged female rats across both areas in response to ISOP. Fos in aged females was blunted in both caudal and middle levels of the NTS and throughout the AP. We conclude that aged females have an impaired response to baroreceptor input after hypotension and are less sensitive to hormones, such as Ang II, that are associated with hypotension. Thus, neurons in the hindbrain areas involved in cardiovascular control may play a role in age-related changes in blood pressure in females

Surface spin-flop phases and bulk discommensurations in antiferromagnets

Phase diagrams as a function of anisotropy D and magnetic field H are obtained for discommensurations and surface states for a model antiferromagnet in which $H$ is parallel to the easy axis. The surface spin-flop phase exists for all $D$. We show that there is a region where the penetration length of the surface spin-flop phase diverges. Introducing a discommensuration of even length then becomes preferable to reconstructing the surface. The results are used to clarify and correct previous studies in which discommensurations have been confused with genuine surface spin-flop states.Comment: 4 pages, RevTeX, 2 Postscript figure

Linear and nonlinear optical spectroscopy of a strongly-coupled microdisk-quantum dot system

A fiber taper waveguide is used to perform direct optical spectroscopy of a microdisk-quantum-dot system, exciting the system through the photonic (light) channel rather than the excitonic (matter) channel. Strong coupling, the regime of coherent quantum interactions, is demonstrated through observation of vacuum Rabi splitting in the transmitted and reflected signals from the cavity. The fiber coupling method also allows the examination of the system's steady-state nonlinear properties, where saturation of the cavity-QD response is observed for less than one intracavity photon.Comment: adjusted references, added minor clarification

Feasibility and acceptability of a primary care liver fibrosis testing pathway centred on the diabetes annual review: PRELUDE1 prospective cohort study protocol.

INTRODUCTION: Non-alcoholic fatty liver disease is the most common chronic liver disease worldwide affecting 20%-25% in the USA and Europe with a 60%-80% lifetime prevalence for people with type 2 diabetes (T2D). Fibrosis has repeatedly been demonstrated to be the major determinant of liver disease morbidity and mortality and there is currently no routine screening for liver fibrosis in at-risk T2D population. METHODS AND ANALYSIS: This 12-month prospective cohort study of automated fibrosis testing uses the fibrosis-4 score (FIB-4) in patients with T2D linked to the investigation of hospital-based versus community-based second-tier transient elastography (TE) testing. We plan to include >5000 participants across 10 General Practitioner (GP) practices in East London and Bristol. This will determine the rate of undiagnosed significant liver fibrosis in a T2D population, the feasibility of two-tier liver fibrosis screening using FIB-4 at the diabetes annual review and subsequent TE delivered either in the community or secondary care settings. This will include an intention-to-treat analysis for all those invited to attend for diabetes annual review. A qualitative substudy regarding the acceptability of the fibrosis screening pathway will comprise semistructured interviews/focus groups with primary care staff (GPs and practice nurses), and patients taking part in the wider study. ETHICS AND DISSEMINATION: This study received a favourable opinion from the Cambridge East research ethics committee. The results of this study will be disseminated in peer-reviewed scientific journals, conference presentations and local diabetes lay panel meetings. TRIAL REGISTRATION NUMBER: ISRCTN14585543

Assessment of workpiece surface integrity and dimensional/geometrical accuracy following finish plunge end milling of holes drilled with worn tools in PM-processed nickel based superalloy

Powder metallurgy (PM) processed nickel-based superalloys are increasingly employed in the hot section of gas turbine engines for parts such as high-pressure (HP) compressors and turbine rotor discs over more traditional cast and wrought options such as Inconel 718 due to its improved high-temperature properties. In this paper, the surface integrity and geometrical/dimensional accuracy of holes initially rough drilled using worn tools and subsequently finish plunge end milled in a proprietary PM-processed Ni-based superalloy, were assessed and compared. The influence of tool wear on hole quality after finish plunge end milling was also investigated. Significant improvement in hole quality was evident following finishing with reductions in surface roughness (up to ~86%), subsurface microhardness (up to ~125 HK0.05) and workpiece microstructure deformation/damage (up to ~80% in terms of average depth) compared to corresponding rough drilled holes. Evidence of chatter marks on holes machined with worn plunge end mills was observed, despite exhibiting reduced surface roughness levels (~45-73%). Generally, somewhat improved hole surface integrity (reduced subsurface deformation by ~47-64%) and geometrical accuracy (circularity decreased by ~10-25%) were produced when employing new tools.</p

Assessment of workpiece surface integrity and dimensional/geometrical accuracy following finish plunge end milling of holes drilled with worn tools in PM-processed nickel based superalloy

Powder metallurgy (PM) processed nickel-based superalloys are increasingly employed in the hot section of gas turbine engines for parts such as high-pressure (HP) compressors and turbine rotor discs over more traditional cast and wrought options such as Inconel 718 due to its improved high-temperature properties. In this paper, the surface integrity and geometrical/dimensional accuracy of holes initially rough drilled using worn tools and subsequently finish plunge end milled in a proprietary PM-processed Ni-based superalloy, were assessed and compared. The influence of tool wear on hole quality after finish plunge end milling was also investigated. Significant improvement in hole quality was evident following finishing with reductions in surface roughness (up to ~86%), subsurface microhardness (up to ~125 HK0.05) and workpiece microstructure deformation/damage (up to ~80% in terms of average depth) compared to corresponding rough drilled holes. Evidence of chatter marks on holes machined with worn plunge end mills was observed, despite exhibiting reduced surface roughness levels (~45-73%). Generally, somewhat improved hole surface integrity (reduced subsurface deformation by ~47-64%) and geometrical accuracy (circularity decreased by ~10-25%) were produced when employing new tools.</p

Quantum description of light pulse scattering on a single atom in waveguides

We present a time dependent quantum calculation of the scattering of a few-photon pulse on a single atom. The photon wave packet is assumed to propagate in a transversely strongly confined geometry, which ensures strong atom-light coupling and allows a quasi 1D treatment. The amplitude and phase of the transmitted, reflected and transversely scattered part of the wave packet strongly depend on the pulse length (bandwidth) and energy. For a transverse mode size of the order of $\lambda^2$, we find nonlinear behavior for a few photons already, or even for a single photon. In a second step we study the collision of two such wave packets at the atomic site and find striking differences between Fock state and coherent state wave packets of the same photon number.Comment: to appear in Phys. Rev.

A three-dimensional study of reconnection, current sheets and jets resulting from magnetic flux emergence in the Sun

We present the results of a set of three-dimensional numerical simulations of magnetic flux emergence from below the photosphere into the corona that include a uniform and horizontal coronal magnetic field mimicking a pre-existing large-scale coronal magnetic system. Cases with different relative orientations of the upcoming and coronal fields are studied. Upon contact, a concentrated current sheet with the shape of an arch or bridge is formed at the interface which marks the positions of maximum jump in the field vector between the two systems. Relative angles above 90 degrees yield abundant magnetic reconnection and plasma heating. The reconnection is seen to be intrisincally three-dimensional in nature, except at singular positions along the current sheet. It drives collimated high-speed and high-temperature outflows only a short distance from the reconnection site that propagate along the ambient magnetic field lines as jets. Due to the low plasma density in the corona, these jets may propagate over large distances and, therefore help distribute high-density and high-temperature plasma along these newly reconnected field lines. The experiments permit to discern and visualize the three-dimensional shape and relative position of the upcoming plasma hill, high-speed jets and subphotospheric flux system. As a result of the reconnection, magnetic field lines from the magnetized plasma below the surface end up as coronal field lines, thus causing a profound change in the connectivity of the magnetic regions in the corona. The experiments presented here thus yield a number of features repeatedly observed with the TRACE satellite and the YOHKOH-SXT detector, like the establishment of connectivity between emergent and pre-existing active regions, local heating and high-velocity outflows.Comment: 13 pages, 7 figures, inpress ApJ