4,809 research outputs found
Observation of time correlation function of multimode two-photon pairs on a rubidium D line
We report the generation of a type-I multimode two-photon state on a rubidium
D line (780 nm) using periodically poled KTiOPO crystals. With a
degenerate optical parametric oscillator far below threshold, we observe an
oscillatory correlation function, the cross-correlation between two photons
shows a cavity bandwidth of about 7.8 MHz. We also use a
Fabry-Prot etalon to filter its most longitudinal modes and
observe its time correlation function. The experimental data are well fitted to
theoretical curves. This system could be utilized for demonstrating storage and
retrieval of narrowband photons in Rb atomic ensembles, which is important for
long-distance quantum communication.Comment: 4 pages, 3 figures, submitted for publication on 29 April 200
An HI View of Galaxy Conformity: HI-rich Environment around HI-excess Galaxies
Using data taken as part of the Bluedisk project we study the connection
between neutral hydrogen (HI) in the environment of spiral galaxies and that in
the galaxies themselves. We measure the total HI mass present in the
environment in a statistical way by studying the distribution of noise peaks in
the HI data cubes obtained for 40 galaxies observed with WSRT. We find that
galaxies whose HI mass fraction is high relative to standard scaling relations
have an excess HI mass in the surrounding environment as well. Gas in the
environment consists of gas clumps which are individually below the detection
limit of our HI data. These clumps may be hosted by small satellite galaxies
and\or be the high-density peaks of a more diffuse gas distribution in the
inter-galactic medium. We interpret this result as an indication for a picture
in which the HI-rich central galaxies accrete gas from an extended gas
reservoir present in their environment.Comment: 15 pages, 13 figures. Accepted for publication in MNRA
An observational and theoretical view of the radial distribution of HI gas in galaxies
We analyze the radial distribution of HI gas for 23 disk galaxies with
unusually high HI content from the Bluedisk sample, along with a similar-sized
sample of "normal" galaxies. We propose an empirical model to fit the radial
profile of the HI surface density, an exponential function with a depression
near the center. The radial HI surface density profiles are very homogeneous in
the outer regions of the galaxy; the exponentially declining part of the
profile has a scale-length of R1, where R1 is the radius where the
column density of the HI is 1 M pc. This holds for all
galaxies, independent of their stellar or HI mass. The homogenous outer
profiles, combined with the limited range in HI surface density in the
non-exponential inner disk, results in the well-known tight relation between HI
size and HI mass. By comparing the radial profiles of the HI-rich galaxies with
those of the control systems, we deduce that in about half the galaxies, most
of the excess gas lies outside the stellar disk, in the exponentially declining
outer regions of the HI disk. In the other half, the excess is more centrally
peaked. We compare our results with existing smoothed-particle hydrodynamical
simulations and semi-analytic models of disk galaxy formation in a
Cold Dark Matter universe. Both the hydro simulations and the semi-analytic
models reproduce the HI surface density profiles and the HI size-mass relation
without further tuning of the simulation and model inputs. In the semi-analytic
models, the universal shape of the outer HI radial profiles is a consequence of
the {\em assumption} that infalling gas is always distributed exponentially.
The conversion of atomic gas to molecular form explains the limited range of HI
surface densities in the inner disk. These two factors produce the tight HI
mass-size relation.Comment: 15 pages, 14 figures, submitted to MNRA
Glutathione-triggered disassembly of isothermally responsive polymer nanoparticles obtained by nanoprecipitation of hydrophilic polymers
The encapsulation and selective delivery of therapeutic compounds within polymeric nanoparticles offers hope for the treatment of a variety of diseases. Traditional approaches to trigger selective cargo release typically rely on polymer degradation which is not always sensitive to the biological location of a material. In this report, we prepare nanoparticles from thermoresponsive polymers with a ‘solubility release catch’ at the chain-end. This release catch is exclusively activated in the presence of intracellular glutathione, triggering an ‘isothermal’ response and promoting a change in polymer solubility. This solubility switch leads to specific and rapid nanoparticle disassembly, release of encapsulated cargo and produces completely soluble polymeric side-products
Growth and Development of Infants with Asymptomatic Congenital Cytomegalovirus Infection
∙The authors have no financial conflicts of interest. Yonsei Med
Estimating quality weights for EQ-5D (EuroQol-5 dimensions) health states with the time trade-off method in Taiwan
Background/PurposeEQ-5D (EuroQol-5 dimensions) is a preference-based measure of health, which is widely used in cost–utility analyses. It has been suggested that each country should develop its own value set. We therefore sought to develop the quality weights of the EQ-5D health states with the time trade-off (TTO) method in Taiwan.MethodsA total of 745 respondents consisting of employees and volunteers in 17 different hospitals were recruited and interviewed. Each of them valued 13 of 73 EQ-5D health states using the TTO method. Based on the three exclusion criteria for valuation data, only 456 (61.21%) respondents were considered eligible for data analysis. The quality weights for all EQ-5D health states were modeled by generalized estimating equations (GEEs).ResultsOver half of the responses were given negative values, and the medical personnel seemed to have a significantly higher TTO value (+0.1) than others after controlling for other predictors. The N3 model (level 3 occurred within at least 1 dimension) yielded an acceptable fit for the observed OTT data [mean absolute error (MAE) = 0.056, R2 = 0.35]. The magnitude of mean absolute differences (MADs) between Taiwan data and those from the UK, Japan, and South Korea ranged from 0.146 to 0.592, but the rank correlation coefficients were all above 0.811.ConclusionThis study reaffirms the differences in health-related preference values across countries. The high proportion of negative values might indicate that we have also partially measured the intensity of fear in addition to the utility of different health states
Associated clinical characteristics of patients with candidemia among different Candida species
BackgroundThe rising incidence of non-albicans Candida (NAC) infection has been associated with a potentially adverse outcome for patients with candidemia. However, categorizing various species causing candidemia into a single NAC group might lead to inappropriate conclusions due to heterogeneity in species. Thus we examined the associated factors among patients with candidemia caused by different species.MethodsThis retrospective study was conducted at a tertiary medical center in Taiwan from 2006 to 2009. Mortality rate, demographic and clinical characteristics, albumin levels, and severity scores of acute illness of patients at the onset of candidemia were analyzed.ResultsA total of 447 episodes among 418 patients were included for analysis. The overall 30-day crude mortality was 48.2%, with no significant difference between C. albicans and NAC candidemia, but apparently C. parapsilosis candidemia was associated with a lower mortality rate. Time to positivity for yeast was significantly different between species. Compared with infection involving C. albicans, more frequent use of total parenteral nutrition, lower Sequential Organ Failure Assessment score and higher albumin levels were observed for C. parapsilosis candidemia.ConclusionIdentifying associated factors for each species may be a more effective approach than single NAC grouping. Time to positivity may be a hint for treatment guidance in candidemia. More frequent use of total parenteral nutrition and less virulent nature were noted for C. parapsilosis candidemia
First Identification of a Patient Colonized With Klebsiella pneumoniae Carrying blaNDM-1 in Taiwan
New Delhi metallo-β-lactamase 1 (NDM-1) is a novel type of metallo-β-lactamase (MBL). Enterobacteriaceae carrying this NDM-1 encoding gene, blaNDM-1, have been identified worldwide. Bacteria carrying blaNDM-1 are not only resistant to carbapenem, but also highly resistant to many classes of antibiotics, which indicate the importance of prompt identification of these bacteria and implementation of strict infection control measures to prevent their transmission. Here, we report the first identification and management of a patient colonized with Klebsiella pneumoniae carrying blaNDM-1 in Taiwan, who returned from New Delhi where he had been hospitalized for a gun-shot injury
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