1,178 research outputs found
An Explorative Study on Sales Distribution in M-commerce
Despite the proliferation of studies on the sales distribution in e-commerce, little research has been conducted on the sales distribution in the m-commerce channel. This study empirically examines the sales distribution of various product categories in the mobile channel, using the large transaction data from a leading e-marketplace in Korea. Overall, transactions in the mobile channel are more concentrated to head products compared to the PC channel sales, but the pattern is inconsistent across product categories. Transactions in product categories of high average price (e.g., computers) and low purchase frequency rate (e.g., health care products) are less concentrated to head products in the mobile channel than the PC channel. The revenue distribution, however, shows the opposite. Head products generate relatively less revenue in the mobile channel than the PC channel. We provide explanations why the mixing results appear across product categories and between the distribution types
Optical properties of iron-based superconductor LiFeAs single crystal
We have measured the reflectivity spectra of the iron based superconductor
LiFeAs (Tc = 17.6 K) in the temperature range from 4 to 300 K. In the
superconducting state (T < Tc), the clear opening of the optical absorption gap
was observed below 25 cm-1, indicating an isotropic full gap formation. In the
normal state (T > Tc), the optical conductivity spectra display a typical
metallic behavior with the Drude type spectra at low frequencies, but we found
that the introduction of the two Drude components best fits the data,
indicating the multiband nature of this superconductor. A theoretical analysis
of the low temperature data (T=4K < Tc) also suggests that two superconducting
gaps best fit the data and their values were estimated as {\Delta}1 = 1.59 meV
and {\Delta}2 = 3.15 meV, respectively. Using the Ferrell-Glover-Tinkham (FGT)
sum rule and dielectric function {\epsilon}1({\omega}), the superconducting
plasma frequency ({\omega}ps) is consistently estimated to be 6,665 cm-1,
implying that about 59 % of the free carriers in the normal state condenses
into the SC condensate. To investigate the various interband transition
processes (for {\omega} > 200 cm-1), we have also performed the local-density
approximation (LDA) band calculation and calculated the optical spectra of the
interband transitions. The theoretical results provided a qualitative agreement
with the experimental data below 4000 cm-1Comment: 19 pages, 5 figures. This paper has been accepted for publication in
New Journal of Physic
Measurement of Velocity and Temperature Profiles in the 1/40 Scaled-Down CANDU-6 Moderator Tank
In order to simulate the CANDU-6 moderator circulation phenomena during steady state operating and accident conditions, a scaled-down moderator test facility has been constructed at Korea Atomic Energy Institute (KAERI). In the present work an experiment using a 1/40 scaled-down moderator tank has been performed to identify the potential problems of the flow visualization and measurement in the scaled-down moderator test facility. With a transparent moderator tank model, a flow field is visualized with a particle image velocimetry (PIV) technique under an isothermal state, and the temperature field is measured using a laser induced fluorescence (LIF) technique. A preliminary CFD analysis is also performed to find out the flow, thermal, and heating boundary conditions with which the various flow patterns expected in the prototype CANDU-6 moderator tank can be reproduced in the experimentopen
Nearly isotropic upper critical fields in a SrFeCoAs single crystal
We study temperature dependent upper critical field of a
SrFeCoAs single crystal (\textit{T}=20.2 K) along
\textit{ab}-plane and \textit{c}-axis through resistivity measurements up to 50
T. For the both crystalline directions, becomes nearly isotropic
at zero temperature limit, reaching 48 T. The temperature dependence of
the curves is explained by interplay between orbital and Pauli
limiting behaviors combined with the two band effects.Comment: Proceedings of M2S-IX, Tokyo 200
Comparison of volume-controlled and pressure-controlled ventilation using a laryngeal mask airway during gynecological laparoscopy
Background: Several publications have reported the successful, safe use of Laryngeal Mask Airway (LMA)-Classic devices in patients undergoing laparoscopic surgery. However, there have been no studies that have examined the application of volume-controlled ventilation (VCV) or pressure-controlled ventilation (PCV) using a LMA during gynecological laparoscopy. The aim of this study is to compare how the VCV and PCV modes and using a LMA affect the pulmonary mechanics, the gas exchange and the cardiovascular responses in patients who are undergoing gynecological laparoscopy. Methods: Sixty female patients were randomly allocated to one of two groups, (the VCV or PCV groups). In the VCV group, baseline ventilation of the lung was performed with volume-controlled ventilation and a tidal volume of 10 ml/kg ideal body weight (IBW). In the PCV group, baseline ventilation of the lung using pressure-controlled ventilation was initiated with a peak airway pressure that provided a tidal volume of 10 ml/kg IBW and an upper limit of 35 cmH2O. The end-tidal CO2, the peak airway pressures (Ppeak), the compliance, the airway resistance and the arterial oxygen saturation were recorded at T1: 5 minutes after insertion of the laryngeal airway, and at T2 and T3: 5 and 15 minutes, respectively, after CO2 insufflation. Results: The Ppeak at 5 minutes and 15 minutes after CO2 insufflation were significantly increased compared to the baseline values in both groups. Also, at 5 minutes and 15 minutes after CO2 insufflation, there were significant differences of the Ppeak between the two groups. The compliance decreased in both groups after creating the pneumopertoneim (P < 0.05). Conclusions: Our results demonstrate that PCV may be an effective method of ventilation during gynecological laparoscopy, and it ensures oxygenation while minimizing the increases of the peak airway pressure after CO2 insufflation. ��� the Korean Society of Anesthesiologists, 2011
La globalización de las artes marciales: el cambio de reglas para los nuevos mercados
El rápido crecimiento de la industria de las artes marciales justifica el profundizar en el conocimiento sobre su proceso de globalización. Hasta la fecha, existe muy poco conocimiento sobre las artes marciales como productos de consumo global y su proceso de difusión. En este artículo, los autores abordan la expansión e integración global de las artes marciales asiáticas. Se examinan en detalle factores como la deportivización y la estandarización, como fuerzas que motivan significativamente el crecimiento de la industria de las artes marciales. También se examinan algunos temas importantes, tales como el entorno político, la cultura, y las estrategias de mercado, en términos de su influencia sobre el desarrollo y el futuro crecimiento de la industria de las artes marciales. Este estudio concluye con una discusión sobre los retos que se presentan y las futuras oportunidades de desarrollo
Model for the inverse isotope effect of FeAs-based superconductors in the -phase-shifted pairing state
The isotope effects for Fe based superconductors are considered by including
the phonon and magnetic fluctuations within the two band Eliashberg theory. We
show that the recently observed inverse isotope effects of Fe, ,\cite{Shirage0903.3515} as well as the large positive
isotope exponent () can naturally arise for the
magnetically induced sign revered s-wave pairing state within reasonable
parameter range. Either experimental report can not be discarded from the
present analysis based on the parameter values they require. The inverse and
positive isotope effects mean, respectively, the interband and intraband
dominant eletron-phonon interaction. We first make our points based on the
analytic result from the square well potential model and present explicit
numerical calculations of the two band Eliashberg theory.Comment: 4 pages and 2 figure
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