97 research outputs found
Symmetry in Full Counting Statistics, Fluctuation Theorem, and Relations among Nonlinear Transport Coefficients in the Presence of a Magnetic Field
We study full counting statistics of coherent electron transport through
multi-terminal interacting quantum-dots under a finite magnetic field.
Microscopic reversibility leads to the symmetry of the cumulant generating
function, which generalizes the fluctuation theorem in the context of quantum
transport. Using this symmetry, we derive the Onsager-Casimir relation in the
linear transport regime and universal relations among nonlinear transport
coefficients.Comment: 4.1pages, 1 figur
Phospholipase C Produced by Clostridium botulinum Types C and D:Comparison of Gene, Enzymatic, and Biological Activities with Those of Clostridium perfringens Alpha-toxin
Clostridium botulinum type C and D strains recently have been found to produce PLC on egg yolk agar plates. To characterize the gene, enzymatic and biological activities of C. botulinum PLCs (Cb-PLCs), the cb-plc genes from 8 strains were sequenced, and 1 representative gene was cloned and expressed as a recombinant protein. The enzymatic and hemolytic activities of the recombinant Cb-PLC were measured and compared with those of the Clostridium perfringens alpha-toxin. Each of the eight cb-plc genes encoded a 399 amino acid residue protein preceded by a 27 residue signal peptide. The protein consists of 2 domains, the N- and C-domains, and the overall amino acid sequence identity between Cb-PLC and alpha-toxin was greater than 50%, suggesting that Cb-PLC is homologous to the alpha-toxin. The key residues in the N-domain were conserved, whereas those in the C-domain which are important in membrane interaction were different than in the alpha-toxin. As expected, Cb-PLC could hydrolyze egg yolk phospholipid, p-nitrophenylphosphorylcholine, and sphingomyelin, and also exhibited hemolytic activity;however, its activities were about 4- to over 200-fold lower than those of alpha-toxin. Although Cb-PLC showed weak enzymatic and biological activities, it is speculated that Cb-PLC might play a role in the pathogenicity of botulism or for bacterial survival
Carotid artery occlusion and colateral circulation in C57black/6J mice detected by synchrotron radiation microangiography
Using monochromatic synchrotron radiation, we performed microangiography inC57BL/6J mice and investigated their vasculature after unilateral and bilateral carotidartery occlusion. Bilateral occlusion of the carotid artery was made by a ligation of theleft common carotid artery followed by a ligation of the right internal carotid artery(ICA) two days later (n=12). Five days after the second surgery, angiography wasperformed. Unilateral occlusion was made by clipping the right ICA and thenangiography was performed immediately (n=5). The control mice did not undergo anyocclusion (n=5). We removed the brain of the bilateral occlusion mice afterangiography and examined the infarction area. The cerebral microvessels in all animalswere clearly visualized. In the control mice, the posterior communicating artery (Pcom)was not visualized. In the unilateral occlusion mice, the anastomosis of thepterygopalatine artery (PPA) and the external carotid artery (ECA) were recognized.The PPA is thus considered to play a role in the collateral vessel between the ICA andthe ECA. The Pcom was not visualized. In the bilateral occlusion mice, the Pcom wasobserved either unilateraly (n=5) or bilateraly (n=5). The Pcom supplied blood flow tothe anterior circulation from the vertebrobasilar arteries. The bilateral occlusion micethat had at least one visualized Pcom did not have any infarction. We could successfullyvisualize the cerebral vasculature of normal mice and carotid artery occluded mice inan in vivo study. Microangiography can demonstrate the development of vasculatureand the blood flow dynamics in mice
Suppressive effects of 2-methacryloyloxyethyl phosphorylcholine (MPC)-polymer on the adherence of Candida species and MRSA to acrylic denture resin
Objectives: The effects of 2-methacryloyloxyethyl phosphorylcholine (MPC)-polymer on the adherence of microorganisms such as non-Candida albicans Candida (NCAC) and methicillin-resistant Staphylococcus aureus (MRSA), frequently detected in oral infections in immunocompromised and/or elderly people, to denture resin material, are still unclear. Here, we report the effects of MPC-polymer on the adherence of C. albicans, NCAC, and MRSA to acrylic denture resin.
Methods: Sixteen strains of C. albicans, seven strains of C. glabrata, two strains of C. tropicalis, one strain of C. parapsilosis, and six strains of MRSA were used. We cultured the fungal/bacterial strains and examined the cell growth and adherence of fungi/bacteria to mucin-coated acrylic denture resin plates (ADRP) with or without MPC-polymer coating, by scanning electron microscopy. The cell surface hydrophobicity of the fungal/bacterial strains was measured by the adsorption to hydrocarbons.
Results: MPC-polymer did not affect the growth of all strains of Candida species and MRSA, but significantly suppressed adherence to ADRP in most strains of C. albicans and all strains of NCAC and MRSA. A significant positive correlation was found between cell hydrophobicity and the reduction rates of microbial adherence to ADRP treated with 5% of MPC-polymer.
Conclusions: MPC-polymer treatment for acrylic resin material suppresses the adherence of C. albicans, NCAC and MRSA via their hydrophilicity interaction.
Clinical significance: The application of MPC-polymer for denture hygiene is potent to prevent oral candidiasis, denture stomatitis and opportunistic infection, caused by Candida species and MRSA, via suppressing the adherence of those fungus/bacteria
A Non-radial Eruption in a Quadrupolar Magnetic Configuration with a Coronal Null
We report one of several homologous non-radial eruptions from NOAA active
region (AR) 11158 that are strongly modulated by the local magnetic field as
observed with the Solar Dynamic Observatory (SDO). A small bipole emerged in
the sunspot complex and subsequently created a quadrupolar flux system.
Non-linear force-free field (NLFFF) extrapolation from vector magnetograms
reveals its energetic nature: the fast-shearing bipole accumulated ~2e31 erg
free energy (10% of AR total) over just one day despite its relatively small
magnetic flux (5% of AR total). During the eruption, the ejected plasma
followed a highly inclined trajectory, over 60 degrees with respect to the
radial direction, forming a jet-like, inverted-Y shaped structure in its wake.
Field extrapolation suggests complicated magnetic connectivity with a coronal
null point, which is favorable of reconnection between different flux
components in the quadrupolar system. Indeed, multiple pairs of flare ribbons
brightened simultaneously, and coronal reconnection signatures appeared near
the inferred null. Part of the magnetic setting resembles that of a
blowout-type jet; the observed inverted-Y structure likely outlines the open
field lines along the separatrix surface. Owing to the asymmetrical
photospheric flux distribution, the confining magnetic pressure decreases much
faster horizontally than upward. This special field geometry likely guided the
non-radial eruption during its initial stage.Comment: 10 pages, 7 figures, 4 movies. Accepted for publication in Ap
Evolution of Magnetic Field and Energy in A Major Eruptive Active Region Based on SDO/HMI Observation
We report the evolution of magnetic field and its energy in NOAA active
region 11158 over 5 days based on a vector magnetogram series from the
Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamic Observatory
(SDO). Fast flux emergence and strong shearing motion led to a quadrupolar
sunspot complex that produced several major eruptions, including the first
X-class flare of Solar Cycle 24. Extrapolated non-linear force-free coronal
fields show substantial electric current and free energy increase during early
flux emergence near a low-lying sigmoidal filament with sheared kilogauss field
in the filament channel. The computed magnetic free energy reaches a maximum of
~2.6e32 erg, about 50% of which is stored below 6 Mm. It decreases by ~0.3e32
erg within 1 hour of the X-class flare, which is likely an underestimation of
the actual energy loss. During the flare, the photospheric field changed
rapidly: horizontal field was enhanced by 28% in the core region, becoming more
inclined and more parallel to the polarity inversion line. Such change is
consistent with the conjectured coronal field "implosion", and is supported by
the coronal loop retraction observed by the Atmospheric Imaging Assembly (AIA).
The extrapolated field becomes more "compact" after the flare, with shorter
loops in the core region, probably because of reconnection. The coronal field
becomes slightly more sheared in the lowest layer, relaxes faster with height,
and is overall less energetic.Comment: Eq. (A1) correcte
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