30 research outputs found
D-Tagatose Effectively Reduces the Number of Streptococcus mutans and Oral Bacteria in Healthy Adult Subjects: A Chewing Gum Pilot Study and Randomized Clinical Trial
We examined the effect of D-Tagatose on the growth of oral bacteria including Streptococcus mutans (S. mutans). Saliva collected from 10 healthy volunteers was plated on BHI medium (to culture total oral bacteria) and MBS medium (to culture S. mutans, specifically). Agar plates of BHI or MBS containing xylitol or D-Tagatose were cultured under aerobic or anaerobic conditions. We then counted the number of colonies. In BHI plates containing D-Tagatose, a complete and significant reduction of bacteria occurred under both aerobic and anaerobic conditions. In MSB medium, significant reduction of S. mutans was also observed. We then performed a doubleblind parallel randomized trial with 19 healthy volunteers. They chewed gum containing xylitol, D-Tagatose, or both for 4 weeks, and their saliva was collected weekly and plated on BHI and MSB media. These plates were cultured under anaerobic conditions. Total bacteria and S. mutans were not effectively reduced in either the D-Tagatose or xylitol gum group. However, S. mutans was significantly reduced in volunteers chewing gum containing both D-Tagatose and xylitol. Thus, D-Tagatose inhibited the growth of S. mutans and many types of oral bacteria, indicating that D-Tagatose intake may help prevent dental caries, periodontitis, and many oral diseases
Completing the Census of Ly-alpha Emitters at the Reionization Epoch
We carried out extended spectroscopic confirmations of Ly-alpha emitters
(LAEs) at z=6.5 and 5.7 in the Subaru Deep Field. Now, the total number of
spectroscopically confirmed LAEs is 45 and 54 at z=6.5 and 5.7, respectively,
and at least 81% (70%) of our photometric candidates at z=6.5 (5.7) have been
spectroscopically identified as real LAEs. We made careful measurements of the
Ly-alpha luminosity, both photometrically and spectroscopically, to accurately
determine the Ly-alpha and rest-UV luminosity functions (LFs). The
substantially improved evaluation of the Ly-alpha LF at z=6.5 shows an apparent
deficit from z=5.7 at least at the bright end, and a possible decline even at
the faint end, though small uncertainties remain. The rest-UV LFs at z=6.5 and
5.7 are in good agreement, at least at the bright end, in clear contrast to the
differences seen in the Ly-alpha LF. These results imply an increase in the
neutral fraction of the intergalactic medium from z=5.7 to 6.5. The rest-frame
equivalent width (EW_0) distribution at z=6.5 seems to be systematically
smaller than z=5.7, and it shows an extended tail toward larger EW_0. The
bright end of the rest-UV LF can be reproduced from the observed Ly-alpha LF
and a reasonable EW_0-UV luminosity relation. Integrating this rest-UV LF
provides the first measurement of the contribution of LAEs to the photon budget
required for reionization. The derived UV LF suggests that the fractional
contribution of LAEs to the photon budget among Lyman break galaxies
significantly increases towards faint magnitudes. Low-luminosity LAEs could
dominate the ionizing photon budget, though this inference depends strongly on
the uncertain faint-end slope of the Ly-alpha LF.Comment: 19 pages, 14 figures. Accepted for publication in Ap
EMPRESS. IX. Extremely Metal-Poor Galaxies are Very Gas-Rich Dispersion-Dominated Systems: Will JWST Witness Gaseous Turbulent High-z Primordial Galaxies?
We present kinematics of 6 local extremely metal-poor galaxies (EMPGs) with
low metallicities () and low stellar masses
(). Taking deep medium-high resolution
() integral-field spectra with 8.2-m Subaru, we resolve the small
inner velocity gradients and dispersions of the EMPGs with H emission.
Carefully masking out sub-structures originated by inflow and/or outflow, we
fit 3-dimensional disk models to the observed H flux, velocity, and
velocity-dispersion maps. All the EMPGs show rotational velocities () of 5--23 km s smaller than the velocity dispersions
() of 17--31 km s, indicating dispersion-dominated () systems affected by inflow and/or outflow. Except
for two EMPGs with large uncertainties, we find that the EMPGs have very large
gas-mass fractions of . Comparing our results with
other H kinematics studies, we find that
decreases and increases with decreasing metallicity, decreasing
stellar mass, and increasing specific star-formation rate. We also find that
simulated high- () forming galaxies have gas fractions and dynamics
similar to the observed EMPGs. Our EMPG observations and the simulations
suggest that primordial galaxies are gas-rich dispersion-dominated systems,
which would be identified by the forthcoming James Webb Space Telescope (JWST)
observations at .Comment: Submitted to ApJ; After revisio
Stable Rotation of a Parametrically Excited Double Pendulum
Abstract: The rotation of a double pendulum with a dc motor installed between the �rst and second pendulums was investigated using both experiments and numerical computations. The first pendulum can rotate freely around one end, while the second pendulum is attached to the other end of the first pendulum � the dc motor attached to the first pendulum causes the second pendulum to rotate with respect to the first pendulum. We clarify that there is a range of rotation speed in which the first pendulum rotates at the same, one-half, or one-third of the rotation speed of the second pendulum, and the stable rotation of the double pendulum is realized without torque control of the dc motor and report the characteristics of the stable rotation of the double pendulum
Friction-Induced Oscillations of a Non-Asbestos Organic Pin Sliding on a Steel Disc
Friction-induced oscillations result in deterioration of performance of disc brakes and are generally undesired. We conduct experimental study of friction-induced oscillations in a non-asbestos organic material / steel pair used in disc brakes of motor vehicles. The tests are done by use of a pin-on-disc machine in which the pin sample is supported on a deformable beam. The adjustable friction parameters are the disc velocity, contact pressure and temperature. The tests show that the friction coefficient decreases with the sliding velocity and increases with the temperature. The friction-induced tangential oscillation of the pin sample occurs with a frequency equal to the first natural frequency of the beam. The effects of the disc velocity and temperature on the oscillation characteristics are investigated. The oscillation amplitude increases with the disc velocity on the interval of velocities below 2 m/s. Temperature changes of several tens of degrees Celsius lead to the oscillation occurrence / decay. The obtained results can be useful for prognostication of friction-induced oscillations in disc brakes with non-asbestos organic pads
Management of a centenarian who underwent emergency laparoscopic cholecystectomy under general anesthesia with subcostal transversus abdominis plane block
Abstract The anesthetic management of centenarians is challenging, since they have loss of functional reserve in all organs. The mortality rate of 25 % is reported in patients over 100 years old who underwent emergency surgery. The transversus abdominis plane block has been shown to provide effective analgesia in laparoscopic cholecystectomy. A 101-year-old woman was diagnosed with grade I (mild) acute cholecystitis with gallstones. An emergency laparoscopic cholecystectomy was scheduled. The patient had a history of hypertension. The patient’s laboratory data showed that she had mild coagulopathy, anemia, thrombocytopenia, and decreased renal function. After induction of general anesthesia, an ultrasound-guided, bilateral subcostal transversus abdominis plane block was performed. Her postoperative course was uneventful. Using the preoperative subcostal transversus abdominis plane block, we were able to avoid hemodynamic instability and to reduce opioid dosage in a centenarian who underwent emergency laparoscopic cholecystectomy under general anesthesia