Proof of the renormalizability of the gradient flow

We give an alternative perturbative proof of the renormalizability of the system defined by the gradient flow and the fermion flow in vector-like gauge theories.Comment: 29 pages, the final version to appear in Nuclear Physics

KINEMATIC CONTRIBUTION OF THE LOWER LIMB TO VERTICAL JAVELIN VELOCITY IN MALE JAVELIN THROWERS

In the javelin throw, vertical release velocity is correlated with throwing record positively. The purpose of this study was to clarify the kinematic contribution of the lower limb to the vertical javelin velocity in male javelin throwers and to examine the movements that enhance the contribution of the lower limb. The throwing movements of 115 male javelin throwers were videotaped and analyzed using a three-dimensional motion-analysis technique. The vertical release velocity for each body part was expressed as the relative velocity. The vertical javelin velocity acquired by lengthening and rotation of the lower limb was calculated by applying an inverted pendulum model. The lower limb contributed positively to the vertical release velocity (12.2 ± 2.8%). The contribution of the lower limb was mainly acquired through rotation. Throwers with higher vertical release velocity showed greater contributions of both rotation and lengthening movements

Mizoribine Inhibits the Proliferation of Renal Stem/Progenitor Cells by G1/S Arrest during Renal Regeneration

Immunosuppressive agents are generally administered to treat kidney diseases. However, it is unclear whether renal stem/progenitor cells are directly affected by the immunosuppressive agents. We used normal rat kidney cells, ureteric bud cells and rat kidney stem/progenitor cells in this study. Mizoribine (MZR), cyclophosphamide (CPA) and cyclosporine (CyA) were added to the culture media of these cells. We evaluated the effects of these immunosuppressive agents on cell proliferation using an electrical cell-substrate impedance sensing system (ECIS) and their effects on the process of renal regeneration using the ischemia-reperfusion (I/R) injury rat model. The ECIS data showed that proliferation of each of the 3 types of cells was significantly suppressed by MZR. MZR treatment enhanced renal tubular injury in ischemia-reperfusion (I/R) injured rats, and significantly decreased levels of M-phase cells and Nestin-positive cells. These results suggested that MZR inhibits the cell cycle of renal stem/progenitor cells;thus, physicians should take note that MZR might affect not only inflammation but also renal regeneration

Hypoxia-inducible factor 1 alpha regulates branching morphogenesis during kidney development

The kidneys are exposed to hypoxic conditions during development. Hypoxia-inducible factor (HIF), an important mediator of the response to hypoxia, is believed to have an important role in development. However, the relationship between HIF and branching morphogenesis has not been elucidated clearly. In this study, we examined whether HIF regulates kidney development. We harvested kidneys from day 13 rat embryos (E13K5) and cultured the organs under normoxic (20% 02/5% CO2) or hypoxic (5% 02/5% CO2) conditions. We evaluated the kidneys based on morphology and gene expression. El3K5 cultured under hypoxic conditions had significantly more ureteric bud (UB) branching than the E13Ks cultured under normoxic conditions. In addition, the mRNA levels of GDNF and GDNF receptor (GFR-alpha l), increased under hypoxic conditions in E13K5. When we cultured E13Ks( with the HIF-1 alpha inhibitor digoxin or with siRNA targeting HIF-l alpha under hypoxic conditions, we did not observe increased UB branching. In addition, the expression of GDNF and GFR-alpha 1 was inhibited under hypoxic conditions when the kidneys were treated with siRNA targeting HIF-1 alpha. We also elucidated that hypoxia inhibited UB cell apoptosis and promoted the expression of FGF7 mRNA levels in metanephric mesenchymal (MM) cells in vitro. These findings suggest that hypoxic condition has important roles in inducing branching morphogenesis during kidney development. Hypoxia might mediate branching morphogenesis via not only GDNF/Ret but also FGF signaling pathway

Origin of the unusually low nitrogen abundances in young populations of the Large Magellanic Cloud

It is a longstanding problem that HII regions and very young stellar populations in the Large Magellanic Cloud (LMC) have the nitrogen abundances ([N/H]) by a factor of ~7 lower than the solar value. We here discuss a new scenario in which the observed unusually low nitrogen abundances can be closely associated with recent collision and subsequent accretion of HI high velocity clouds (HVCs) that surround the Galaxy and have low nitrogen abundances. We show that if the observed low [N/H] is limited to very young stars with ages less than ~10^7 yr, then the collision/accretion rate of the HVCs onto the LMC needs to be ~ 0.2 M_sun/yr (corresponding to the total HVC mass of 10^6-10^7 M_sun) to dilute the original interstellar medium (ISM) before star formation. The required accretion rate means that even if the typical mass of HVCs accreted onto the LMC is ~ 10^7 M_sun, the Galaxy needs to have ~2500 massive HVCs within the LMC's orbital radius with respect to the Galactic center. The required rather large number of massive HVCs drives us to suggest that the HVCs are not likely to efficiently dilute the ISM of the LMC and consequently lower the [N/H]. We thus suggest the transfer of gas with low [N/H] from the Small Magellanic Cloud (SMC) to the LMC as a promising scenario that can explain the observed low [N/H].Comment: 24pages, 6 figures, accepted in Ap

Expression and Localization of TRK-Fused Gene Products in the Rat Brain and Retina

The TRK-fused gene (TFG in human, Tfg in rat) was originally identified in human papillary thyroid cancer as a chimeric form of the NTRK1 gene. It has been reported that the gene product (TFG) plays a role in regulating phosphotyrosine-specific phosphatase-1 activity. However, no information regarding the localization of Tfg in rat tissues is available. In this study, we investigated the expression of Tfg mRNA in normal rat tissues using reverse transcription-polymerase chain reaction (RT-PCR). We also produced an antibody against Tfg gene products and examined the localization of TFG in the rat brain and retina. The RT-PCR experiments demonstrated that two types of Tfg mRNA were expressed in rat tissues: the conventional form of Tfg (cTfg) and a novel variant form, retinal Tfg (rTfg). RT-PCR analyses demonstrated that cTfg was ubiquitously expressed in rat tissues, while rTfg was predominantly expressed in the brain and retina. Western blot analysis demonstrated two bands with molecular weights of about 30 kDa and 50 kDa in the rat brain. Immunohistochemistry indicated that TFG proteins were predominantly expressed by neurons in the brain. In the rat retina, intense TFG-immunoreactivity was detected in the layer of rods and cones and the outer plexiform layer

Formation of the off-center bar in the Large Magellanic Cloud: A collision with a dark satellite ?

Recent observations on structural properties of the Large Magellanic Cloud (LMC) based on the Deep Near-Infrared Southern Sky Survey (DENIS) and Two Micron All-Sky Survey (2MASS) have revealed that the LMC has an off-center bar even in the older stellar populations. Previous dynamical models including tidal interaction between the LMC, the Small Magellanic Cloud (SMC), and the Galaxy, however, did not reproduce so well the older off-center bar. We here show that the off-center bar can be formed if the LMC with an already existing bar can collide with a low-mass Galactic subhalo as massive as 5 * 10^8 M_sun (corresponding roughly to a few % of the LMC mass). The simulated stellar distribution after the collision appears to show an ``off-center bar'', not because the center of the bar significantly deviates from the dynamical center of the LMC, but because the underlying stellar distribution of the disk is significantly asymmetric with respect to the center of the bar. We discuss whether off-center bars observed in Magellanic-type dwarf galaxies can be formed as a result of tidal interaction with low-mass halos with no or little visible matters.Comment: 5 pages, 5 figures, accepted by MNRAS Letter

Dark impact and galactic star formation: Origin of the Gould belt

The Milky Way has a giant stellar structure in the solar neighborhood, which has a size of $\sim 1$ kpc, a mass of $\sim 10^6 {\rm M}_{\odot}$, and a ring-like distribution of young stars. Fundamental physical properties of this local enigmatic structure, known as the Gould belt (GB), have not been reproduced by previously proposed models. We first show that the local enigmatic structure can be formed about 30 Myr ago as a result of a high-speed, oblique collision between a gas cloud with a mass of $\sim 10^6 {\rm M}_{\odot}$ and a dark matter clump with a mass of $\sim 10^7 {\rm M}_{\odot}$ based on numerical simulations of the collision. We find that strong dynamical impact of the clump transforms the flattened cloud into a ring-like stellar structure after induced star formation within the cloud. Our simulations furthermore demonstrate that the stellar structure is moderately elongated and significantly inclined with respect to the disk of the Milky Way owing to the strong tidal torque by the colliding clump. We thus suggest that the GB is one of stellar substructures formed from collisions between gas clouds and dark matter clumps predicted in the hierarchical clustering scenario of galaxy formation. We also suggest that collisions of dark matter clumps with their host galaxies can significantly change star formation histories for some of their gas clouds thus influence galactic global star formation histories to some extent.Comment: 5 pages, 4 figures, accepted by MNRAS Letter