9,508 research outputs found
Nuclear surface diffuseness revealed in nucleon-nucleus diffraction
Nuclear surface provides useful information on nuclear radius, nuclear
structure as well as properties of nuclear matter. We discuss the relationship
between the nuclear surface diffuseness and elastic scattering differential
cross section at the first diffraction peak of high-energy nucleon-nucleus
scattering as an efficient tool in order to extract the nuclear surface
information from limited experimental data involving short-lived unstable
nuclei. The high-energy reaction is described by a reliable microscopic
reaction theory, the Glauber model. Extending the idea of the black sphere
model, we find one-to-one correspondence between the nuclear bulk structure
information and proton elastic scattering diffraction peak. This implies that
we can extract both the nuclear radius and diffuseness simultaneously, using
the position of the first diffraction peak and its magnitude of the elastic
scattering differential cross section. We confirm the reliability of this
approach by using realistic density distributions obtained by a mean-field
model.Comment: 12 pages, 12 figures, to appear in Phys. Rev.
Emergent Antiferromagnetism in D-wave Superconductor with Strong Paramagnetic Pair-Breaking
It is theoretically shown that, in the four-fold symmetric d-wave
superconducting phase, a paramagnetic pair-breaking (PPB) enhanced sufficiently
by increasing the applied magnetic field induces not only the
Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) superconducting state but also an
incommensurate antiferromagnetic (AFM) order with Q-vector parallel to a gap
node. This AFM ordering tends to occur only below H_{c2} at low temperatures,
i.e., in the presence of a nonvanishing superconducting energy gap
rather than in the normal phase. Through a detailed study on the resulting AFM
order and its interplay with the FFLO spatial modulation of , it is
argued that the strange high field and low temperature (HFLT) superconducting
phase of CeCoIn_5 is a coexisting phase of the FFLO and incommensurate AFM
orders, and that this PPB mechanism of an AFM ordering is also the origin of
the AFM quantum critical fluctuation which has occurred close to H_{c2}(0) in
several unconventional superconductors including CeCoIn_5.Comment: 22 pages, 12 figures.2 references and related comnments are
added.Accepted for publication in Phys. Rev.
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Radiative impact of mixing state of black carbon aerosol in Asian outflow
The radiative impact of the mixing state of black carbon (BC) aerosol is investigated in Asian outflow. The mixing state and size distribution of BC aerosol were measured with a ground-based single-particle soot photometer at a remote island (Fukue) in Japan in spring 2007. The mass concentration of BC in Asian continental air masses reached 0.5 ÎŒg m-3, with a mass median diameter of 200-220 nm. The median value of the shell/core diameter ratio increased to âŒ1.6 in Asian continental and maritime air masses with a core diameter of 200 mn, while in free tropospheric and Japanese air masses it was 1.3-1.4. On the basis of theoretical calculations using the size distribution and mixing state of BC aerosol, scattering and absorption properties of PM1 aerosols were calculated under both dry and ambient conditions, considering the hygroscopic growth of aerosols. It was estimated that internal mixing enhanced the BC absorption by a factor of 1.5-1.6 compared to external mixing. The calculated absorption coefficient was 2-3 times higher in Asian continental air masses than in clean air. Coatings reduced the single-scattering albedo (SSA) of PM1 aerosol by 0.01 -0.02, which indicates the importance of the mixing state of BC aerosol in evaluating its radiative influence. The SSA was sensitive to changes in air mass type, with a value of âŒ0.98 in Asian continental air masses and âŒ0.95 in Japanese and free tropospheric air masses under ambient conditions. Copyright 2008 by the American Geophysical Union
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Suppression of planar cell polarity signaling and migration in glioblastoma by Nrdp1-mediated Dvl polyubiquitination.
The lethality of the aggressive brain tumor glioblastoma multiforme (GBM) results in part from its strong propensity to invade surrounding normal brain tissue. Although oncogenic drivers such as epidermal growth factor receptor activation and Phosphatase and Tensin homolog inactivation are thought to promote the motility and invasiveness of GBM cells via phosphatidylinostitol 3-kinase activation, other unexplored mechanisms may also contribute to malignancy. Here we demonstrate that several components of the planar cell polarity (PCP) arm of non-canonical Wnt signaling including VANGL1, VANGL2 and FZD7 are transcriptionally upregulated in glioma and correlate with poorer patient outcome. Knockdown of the core PCP pathway component VANGL1 suppresses the motility of GBM cell lines, pointing to an important mechanistic role for this pathway in glioblastoma malignancy. We further observe that restoration of Nrdp1, a RING finger type E3 ubiquitin ligase whose suppression in GBM also correlates with poor prognosis, reduces GBM cell migration and invasiveness by suppressing PCP signaling. Our observations indicate that Nrdp1 physically interacts with the Vangl1 and Vangl2 proteins to mediate the K63-linked polyubiquitination of the Dishevelled, Egl-10 and Pleckstrin (DEP) domain of the Wnt pathway protein Dishevelled (Dvl). Ubiquitination hinders Dvl binding to phosphatidic acid, an interaction necessary for efficient Dvl recruitment to the plasma membrane upon Wnt stimulation of Fzd receptor and for the propagation of downstream signals. We conclude that the PCP pathway contributes significantly to the motility and hence the invasiveness of GBM cells, and that Nrdp1 acts as a negative regulator of PCP signaling by inhibiting Dvl through a novel polyubiquitination mechanism. We propose that the upregulation of core PCP components, together with the loss of the key negative regulator Nrdp1, act coordinately to promote GBM invasiveness and malignancy
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CD24 signalling through macrophage Siglec-10 is a target for cancer immunotherapy.
Ovarian cancer and triple-negative breast cancer are among the most lethal diseases affecting women, with few targeted therapies and high rates of metastasis. Cancer cells are capable of evading clearance by macrophages through the overexpression of anti-phagocytic surface proteins called 'don't eat me' signals-including CD471, programmed cell death ligand 1 (PD-L1)2 and the beta-2 microglobulin subunit of the major histocompatibility class I complex (B2M)3. Monoclonal antibodies that antagonize the interaction of 'don't eat me' signals with their macrophage-expressed receptors have demonstrated therapeutic potential in several cancers4,5. However, variability in the magnitude and durability of the response to these agents has suggested the presence of additional, as yet unknown 'don't eat me' signals. Here we show that CD24 can be the dominant innate immune checkpoint in ovarian cancer and breast cancer, and is a promising target for cancer immunotherapy. We demonstrate a role for tumour-expressed CD24 in promoting immune evasion through its interaction with the inhibitory receptor sialic-acid-binding Ig-like lectin 10 (Siglec-10), which is expressed by tumour-associated macrophages. We find that many tumours overexpress CD24 and that tumour-associated macrophages express high levels of Siglec-10. Genetic ablation of either CD24 or Siglec-10, as well as blockade of the CD24-Siglec-10 interaction using monoclonal antibodies, robustly augment the phagocytosis of all CD24-expressing human tumours that we tested. Genetic ablation and therapeutic blockade of CD24 resulted in a macrophage-dependent reduction of tumour growth in vivo and an increase in survival time. These data reveal CD24 as a highly expressed, anti-phagocytic signal in several cancers and demonstrate the therapeutic potential for CD24 blockade in cancer immunotherapy
Absorption-free optical control of spin systems:the quantum Zeno effect in optical pumping
We show that atomic spin motion can be controlled by circularly polarized
light without light absorption in the strong pumping limit. In this limit, the
pumping light, which drives the empty spin state, destroys the Zeeman coherence
effectively and freezes the coherent transition via the quantum Zeno effect. It
is verified experimentally that the amount of light absorption decreases
asymptotically to zero as the incident light intensity is increased.Comment: 4 pages with 4 figure
Motion-Induced Magnetic Resonance of Rb Atoms in a Periodic Magnetostatic Field
We demonstrate that transitions between Zeeman-split sublevels of Rb atoms
are resonantly induced by the motion of the atoms (velocity: about 100 m/s) in
a periodic magnetostatic field (period: 1 mm) when the Zeeman splitting
corresponds to the frequency of the magnetic field experienced by the moving
atoms. A circularly polarized laser beam polarizes Rb atoms with a velocity
selected using the Doppler effect and detects their magnetic resonance in a
thin cell, to which the periodic field is applied with the arrays of parallel
current-carrying wires.Comment: 4 pages, 4 figures; minor corrections, Ref. [9] removed, published in
PR
Velocity-selective sublevel resonance of atoms with an array of current-carrying wires
Resonance transitions between the Zeeman sublevels of optically-polarized Rb
atoms traveling through a spatially periodic magnetic field are investigated in
a radio-frequency (rf) range of sub-MHz. The atomic motion induces the
resonance when the Zeeman splitting is equal to the frequency at which the
moving atoms feel the magnetic field oscillating. Additional temporal
oscillation of the spatially periodic field splits a motion-induced resonance
peak into two by an amount of this oscillation frequency. At higher oscillation
frequencies, it is more suitable to consider that the resonance is mainly
driven by the temporal field oscillation, with its velocity-dependence or
Doppler shift caused by the atomic motion through the periodic field. A
theoretical description of motion-induced resonance is also given, with
emphasis on the translational energy change associated with the internal
transition.Comment: 7 pages, 3 figures, final versio
Spin Nutation Induced by Atomic Motion in a Magnetic Lattice
An atom moving in a spatially periodic field experiences a temporary periodic
perturbation and undergoes a resonance transition between atomic internal
states when the transition frequency is equal to the atomic velocity divided by
the field period. We demonstrated that spin nutation was induced by this
resonant transition in a polarized rubidium (Rb) atomic beam passing through a
magnetic lattice. The lattice was produced by current flowing through an array
of parallel wires crossing the beam. This array structure, reminiscent of a
multiwire chamber for particle detection, allowed the Rb beam to pass through
the lattice at a variety of incident angles. The dephasing of spin nutation was
reduced by varying the incident angle.Comment: 11 pages, 4 figures, submitted to Phys. Rev.
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