Generating asymptotically optimal broadcasting schedules to minimize average waiting time

The performance of a Video-on-Demand broadcasting scheme is commonly evaluated by the maximum waiting time encountered by the customer before viewing can start. This paper addresses the issue of minimizing the average waiting time. Recently, we proposed Harmonic Block Windows scheduling to specifically minimize the average waiting time for given bandwidth. Here, we present an efficient heuristic algorithm that generates asymptotically optimal Harmonic Block Windows schedules. Using simulation, we demonstrate that, as we increase the “block size”, the normalized average waiting time of these schedules approaches the theoretical minimum achievable by any “fixed start points” schedule.     

Development of ion transportation, extraction and neutralization systems for atomic beam resonance method

A device that produces a low-energy and largely spin polarized RI beam based on the atomic beam resonance method (RIABR) has been developed. We have performed measurements of stopping and drifting an incoming RI ion beam in a gas chamber, extraction of the ions into a vacuum region, and neutralization of the extracted low-energy ion beam. The drift efficiency of RI ions in a gas and the extraction efficiency at a Laval-type glass nozzle were found to be 0.72±0.04 and 0.033, respectively. The result of the experiment for the neutralization is also discussed.     

Dechlorination of poly(vinyl chloride) using NaOH in ethylene glycol under atmospheric pressure

A solution of NaOH dissolved in ethylene glycol (EG) was effective in the dechlorination of poly(vinyl chloride) (PVC) at atmospheric pressure. The degree of dechlorination increased with increasing temperature, reaching a maximum of 97.8% at 190 °C. The dechlorination proceeded under chemical control and exhibited first-order kinetics with an apparent activation energy of 170 kJ mol⁻¹. The apparent rate constant for dechlorination in 1.0 M NaOH/EG was approximately 150 times greater than that in 1.0 M NaOH/H₂O. In addition, dechlorination was faster at atmospheric pressure in NaOH/EG than under high pressure in NaOH/H₂O. The dechlorination reaction occurs via a combination of E2 and S_N2 mechanisms.     

Phase transition of L-Ser monohydrate crystal studied by (13)C solid-state NMR

We used gravimetric analysis (GA) and (13)C solid-state nuclear magnetic resonance (NMR) to study solid-phase transition from the transparent single crystal of L-serine (L-Ser) monohydrate to a turbid powder. We found that L-Ser monohydrate loses water molecules and transforms into an anhydrate, thus experimentally demonstrating Frey's assumption. Application of a handmade cross-polarization (CP) NMR probe with a saddle-type coil to the oriented crystal of the L-Ser monohydrate revealed the dehydration mechanism. Furthermore, the chemical shift tensor components of the carboxyl carbon in L-Ser monohydrate were determined. The difference in the tensor component of delta(22) between the monohydrate and anhydrate forms was more than 7 ppm, probably owing to differences in the hydrogen-bonding structure of each form.     

Enzymatic synthesis of glucoside derivatives of validamine and valienamine.

alpha- And beta-glucoside derivatives of validamine and valienamine were prepared by enzymatic transglucosidation using alpha- and beta-glucosidase of Rhodotorula lactosa. The structures of these derivatives have been elucidated by 13C- and 1H-nuclear magnetic resonance spectral analysis. Thus, 7-alpha-glucoside, 7-alpha-isomaltoside, and 4-alpha-glucoside of validamine and 7-alpha-glucoside, 7-alpha-isomaltoside, 4-alpha-glucoside, and 4-alpha-isomaltoside of valienamine were obtained from maltose and validamine or valienamine using alpha-glucosidase. 7-beta-glucoside, 2-beta-glucoside, and 4-beta-glucoside of validamine or valienamine were obtained from cellobiose and validamine or valienamine using beta-glucosidase. These derivatives were tested for alpha-glucosidase inhibitory activity on rat small intestinal glycosidases.     

Solution structures of 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquid saturated with CO2: Experimental evidence of specific anion-CO2 interaction

X-ray diffraction measurements for 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquid ([BMIM][PF6])-CO2 systems were carried out at high pressures with a newly developed polymer cell. The intermolecular distribution functions (g(inter)(r)) were obtained at 25 degrees C for neat [BMIM][PF6] and its solutions saturated with CO2 at 4 and 15 MPa, where the mole fractions (x) of CO2 correspond to 0.5 and 0.7, respectively. In g(inter)(r) for x = 0.5, two peaks appeared at around 2.8 and 3.2 A. These two peaks in g(inter)(r) appreciably increased for x = 0.7; moreover, there was another peak observed at approximately 3.8 A. Only assuming the correlations between CO2 and [PF6]-, it is reasonably determined that the nearest-neighbor P([PF6]-). . .C(CO2) distances are 3.57 and 3.59 A with the coordination numbers being 1.8 and 4.0 for x = 0.5 and 0.7, respectively. It is concluded that CO2 molecules are preferentially solvated to the [PF6]- anion.