253 research outputs found
A Hamiltonian description of finite-time singularity in Euler's fluid equations
The recently proposed low degree-of-freedom model of Moffat and Kimura [1,2]
for describing the approach to finite-time singularity of the incompressible
Euler fluid equations is investigated. The model assumes an initial
finite-energy configuration of two vortex rings placed symmetrically on two
tilted planes. The Hamiltonian structure of the inviscid limit of the model is
obtained. The associated noncanonical Poisson bracket [3] and two invariants,
one that serves as the Hamiltonian and the other a Casimir invariant, are
discovered. It is shown that the system is integrable with a solution that lies
on the intersection for the two invariants, just as for the free rigid body of
mechanics whose solution lies on the intersection of the kinetic energy and
angular momentum surfaces. Also, a direct quadrature is given and used to
demonstrate the Leray form for finite-time singularity in the model. To the
extent the Moffat and Kimura model accurately represents Euler's ideal fluid
equations of motion, we have shown the existence of finite-time singularity
Determination of the structure of Ne by full-microscopic framework
We perform the first quantitative analysis of the reaction cross sections of
Ne by C at 240 MeV/nucleon, using the double-folding model
(DFM) with the Melbourne -matrix and the deformed projectile density
calculated by the antisymmetrized molecular dynamics (AMD). To describe the
tail of the last neutron of Ne, we adopt the resonating group method
(RGM) combined with AMD. The theoretical prediction excellently reproduce the
measured cross sections of Ne with no adjustable parameters. The
ground state properties of Ne, i.e., strong deformation and a halo
structure with spin-parity , are clarified.Comment: 4 pages, 4 figures, 2 table
Deformation effect on total reaction cross sections for neutron-rich Ne-isotopes
Isotope-dependence of measured reaction cross sections in scattering of
Ne isotopes from C target at 240 MeV/nucleon is analyzed by
the double-folding model with the Melbourne -matrix. The density of
projectile is calculated by the mean-field model with the deformed Wood-Saxon
potential. The deformation is evaluated by the antisymmetrized molecular
dynamics. The deformation of projectile enhances calculated reaction cross
sections to the measured values.Comment: 6 pages, 4 figures, 2 table
Herpes simplex virus type 1 UL14 tegument protein regulates intracellular compartmentalization of major tegument protein VP16
<p>Abstract</p> <p>Background</p> <p>Herpes simplex virus type 1 (HSV-1) has a complicated life-cycle, and its genome encodes many components that can modify the cellular environment to facilitate efficient viral replication. The protein UL14 is likely involved in viral maturation and egress (Cunningham C. et al), and it facilitates the nuclear translocation of viral capsids and the tegument protein VP16 during the immediate-early phase of infection (Yamauchi Y. et al, 2008). UL14 of herpes simplex virus type 2 exhibits multiple functions (Yamauchi Y. et al, 2001, 2002, 2003).</p> <p>Methods</p> <p>To better understand the function(s) of UL14, we generated VP16-GFP-incorporated UL14-mutant viruses with either single (K51M) or triple (R60A, R64A, E68D) amino acid substitutions in the heat shock protein (HSP)-like sequence of UL14. We observed the morphology of cells infected with UL14-null virus and amino acid-substituted UL14-mutant viruses at different time points after infection.</p> <p>Results</p> <p>UL14(3P)-VP16GFP and UL14D-VP16GFP (UL14-null) viruses caused similar defects with respect to growth kinetics, compartmentalization of tegument proteins, and cellular morphology in the late phase. Both the UL14D-VP16GFP and UL14(3P)-VP16GFP viruses led to the formation of an aggresome that incorporated some tegument proteins but did not include nuclear-egressed viral capsids.</p> <p>Conclusions</p> <p>Our findings suggest that a cluster of charged residues within the HSP-like sequence of UL14 is important for the molecular chaperone-like functions of UL14, and this activity is required for the acquisition of functionality of VP16 and UL46. In addition, UL14 likely contributes to maintaining cellular homeostasis following infection, including cytoskeletal organization. However, direct interactions between UL14 and VP16, UL46, or other cellular or viral proteins remain unclear.</p
High hydrostatic pressure induces counterclockwise to clockwise reversals of the Escherichia coli flagellar motor.
The bacterial flagellar motor is a reversible rotary machine that rotates a left-handed helical filament, allowing bacteria to swim toward a more favorable environment. The direction of rotation reverses from counterclockwise (CCW) to clockwise (CW), and vice versa, in response to input from the chemotaxis signaling circuit. CW rotation is normally caused by binding of the phosphorylated response regulator CheY (CheY-P), and strains lacking CheY are typically locked in CCW rotation. The detailed mechanism of switching remains unresolved because it is technically difficult to regulate the level of CheY-P within the concentration range that produces flagellar reversals. Here, we demonstrate that high hydrostatic pressure can induce CW rotation even in the absence of CheY-P. The rotation of single flagellar motors in Escherichia coli cells with the cheY gene deleted was monitored at various pressures and temperatures. Application of >120 MPa pressure induced a reversal from CCW to CW at 20°C, although at that temperature, no motor rotated CW at ambient pressure (0.1 MPa). At lower temperatures, pressure-induced changes in direction were observed at pressures of <120 MPa. CW rotation increased with pressure in a sigmoidal fashion, as it does in response to increasing concentrations of CheY-P. Application of pressure generally promotes the formation of clusters of ordered water molecules on the surfaces of proteins. It is possible that hydration of the switch complex at high pressure induces structural changes similar to those caused by the binding of CheY-P
Ground-state properties of neutron-rich Mg isotopes
We analyze recently-measured total reaction cross sections for 24-38Mg
isotopes incident on 12C targets at 240 MeV/nucleon by using the folding model
and antisymmetrized molecular dynamics(AMD). The folding model well reproduces
the measured reaction cross sections, when the projectile densities are
evaluated by the deformed Woods-Saxon (def-WS) model with AMD deformation.
Matter radii of 24-38Mg are then deduced from the measured reaction cross
sections by fine-tuning the parameters of the def-WS model. The deduced matter
radii are largely enhanced by nuclear deformation. Fully-microscopic AMD
calculations with no free parameter well reproduce the deduced matter radii for
24-36Mg, but still considerably underestimate them for 37,38Mg. The large
matter radii suggest that 37,38Mg are candidates for deformed halo nucleus. AMD
also reproduces other existing measured ground-state properties (spin-parity,
total binding energy, and one-neutron separation energy) of Mg isotopes.
Neutron-number (N) dependence of deformation parameter is predicted by AMD.
Large deformation is seen from 31Mg with N = 19 to a drip-line nucleus 40Mg
with N = 28, indicating that both the N = 20 and 28 magicities disappear. N
dependence of neutron skin thickness is also predicted by AMD.Comment: 15 pages, 13 figures, to be published in Phys. Rev.
Autoimmune Pancreatitis Accompanied with Recurrence of Bladder Cancer: Difficulty in Diagnosis and Management of Systemic Lesions in a Case with Autoimmune Pancreatitis
Context A case of autoimmune pancreatitis develops a hepatic metastasis of bladder cancer resected over 5 years before, mimicking a pseudotumor of the liver. Case report A 71-year-old man with a surgical history of bladder cancer (pT4, G2>3, N (+)) later developed autoimmune pancreatitis. Diagnosis of autoimmune pancreatitis was not problematic; however, a variety of systemic disorders appeared after the onset of autoimmune pancreatitis, possibly associated with autoimmune disorder or steroid therapy. These included pancreatic stone attack, septic shock due to ureteral stenosis, and bloody phlegm due to a lung aspergilloma. These events were not easily controlled but were managed with clinical efforts. In the following course, pelvic lymph nodes gradually enlarged and a hepatic mass occurred at 5 years and 6 months after total cystectomy. Several candidates were considered for the hepatic lesion including inflammatory pseudotumor, cholangiocellular carcinoma, and hepatic adenoma. However, percutaneous biopsy confirmed metastasis of the bladder cancer. In general, recurrence after 5 years following cystectomy is extremely rare in cases of pT4 bladder cancer with lymph node metastasis. Conclusions Patients of autoimmune pancreatitis display various problematic scenarios in diagnosis and long-term management, not only for their pancreatic lesions but also for systemic lesions.Image: Histology of percutaneous hepatic biopsy showed urothelial carcinoma
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