Monte Carlo Model for Studying the Effects of Melanin Concentrations on Retina Light Absorption

We developed a Monte Carlo model to calculate light absorption in human and mouse retinas. The retina was modeled as a five-layer spherical structure. The effects of melanin concentrations in the retinal pigment epithelium (RPE) and choroid layer were studied. Variations of blood content in choroid were also considered in the simulation. Our simulation results indicated that light absorption in neural retina was at least 20% higher in albino subjects than in pigmented subjects under both photobleaching and dark-adapted conditions. It can be four times higher at optical wavelengths corresponding to minimal hemoglobin absorption. The elevated absorption at neural retina was attributed to the light backscattered from the choroid and sclera layers. This simulation model may provide useful information in studying light-induced retina damage

Preference of food saltiness and willingness to consume low-sodium content food in a Chinese population

OBJECTIVE: To compare the preference of food saltiness and the willingness to consume low‐sodium food among hypertensive older people, non‐hypertensive older people and non‐hypertensive young people in a Chinese population. DESIGN: A cross‐sectional study based on a quota sample. Three saltiness options (low‐sodium, medium-sodium and high‐sodium) of soup and bread were offered to each participant who rated the taste of each food on a 5‐point Likert scale. Then, the participants rated their willingness to consume the low-sodium content foods on a 5‐point Likert scale, given they were informed of the benefit of the low-sodium option. Generalised linear mixed model and multiple linear regression were used to analyse the data. SETTING: Elderly centres and community centres in Hong Kong. PARTICIPANTS: Sixty hypertensive older people, 49 non‐hypertensive older people and 60 non-hypertensive young people were recruited from June to August 2014. Measurements: The tastiness score and the willingness score were the primary outcome measures. The Chinese Health Literacy Scale for Low Salt Consumption – Hong Kong population (CHLSalt‐HK) was also assessed. RESULTS: The tastiness rating of the high‐sodium option of soup was significantly lower than the medium‐sodium option (p<0.001), but there was no significant difference between the low‐sodium and the medium‐sodium options (p=0.204). For bread, tastiness rating of the low‐sodium option and the high‐sodium option were significantly lower than the medium‐sodium option (p<0.001 for both options). The tastiness score of soup did not have significant difference across the groups (p=0.181), but that of bread from the hypertensive older adults (p=0.012) and the non‐hypertensive older adults (p=0.006) was significantly higher than the non‐hypertensive young adults. Higher willingness rating to consume the low‐sodium option was significantly (p<0.001) associated with higher tastiness rating of the low-sodium option of soup and bread, and weakly associated with higher health literacy of low salt intake (soup: p=0.041; bread: p=0.024). Hypertensive older adults tended to be more willing to consume the low‐sodium option than non‐hypertensive older adults for soup (p=0.009), there was insignificant difference between non‐hypertensive older adults and non‐hypertensive young adults (p=0.156). For bread, there was insignificant difference in willingness rating to consume low‐sodium option (p=0.375). CONCLUSION: Older people are at a higher risk of hypertension, reduction of salt intake is important for them to reduce their risk of cardiovascular diseases. There is room for reducing the sodium content of soup, while the sodium in bread should be reduced progressively. Improving the taste of low‐sodium food may help to promote reduction in dietary sodium intake.postprin

Factors controlling tropospheric O3, OH, NOx, and SO2 over the tropical Pacific during PEM-Tropics B

Observations over the tropical Pacific during the Pacific Exploratory Mission (PEM)-Tropics B experiment (March-April 1999) are analyzed. Concentrations of CO and long-lived nonmethane hydrocarbons in the region are significantly enhanced due to transport of pollutants from northern industrial continents. This pollutant import also enhances moderately O3 concentrations but not NOx concentrations. It therefore tends to depress OH concentrations over the tropical Pacific. These effects contrast to the large enhancements of O3 and NOx concentrations and the moderate increase of OH concentrations due to biomass burning outflow during the PEM-Tropics A experiment (September-October 1996). Observed CH3I concentrations, as in PEM-Tropics A, indicate that convective mass outflux in the middle and upper troposphere is largely independent of altitude over the tropical Pacific. Constraining a one-dimensiohal model with CH3I observations yields a 10-day timescale for convective turnover of the free troposphere, a factor of 2 faster than during PEM-Tropics A. Model simulated HO2, CH2O, H2O2, and CH3OOH concentrations are generally in agreement with observations. However, simulated OH concentrations are lower (∼25%) than observations above 6 km. Whereas models tend to overestimate previous field measurements, simulated HNO3 concentrations during PEM-Tropics B are too low (a factor of 2-4 below 6 km) compared to observations. Budget analyses indicate that chemical production of O3 accounts for only 50% of chemical loss; significant transport of O3 into the region appears to take place within the tropics. Convective transport of CH3OOH enhances the production of HOx and O3 in the upper troposphere, but this effect is offset by HOx loss due to the scavenging of H2O2. Convective transport and scavenging of reactive nitrogen species imply a necessary source of 0.4-1 Tg yr-1 of NOx in the free troposphere (above 4 km) over the tropics. A large fraction of the source could be from marine lightning. Oxidation of DMS transported by convection from the boundary layer could explain the observed free tropospheric SO2 concentrations over the tropical Pacific. This source of DMS due to convection, however, would imply in the model free tropospheric concentrations much higher than observed. The model overestimate cannot be reconciled using recent kinetics measurements of the DMS-OH adduct reaction at low pressures and temperatures and may reflect enhanced OH oxidation of DMS during convection. Copyright 2001 by the American Geophysical Union

No-cloning theorem and teleportation criteria for quantum continuous variables

We discuss the criteria presently used for evaluating the efficiency of quantum teleportation schemes for continuous variables. Using an argument based upon the difference between 1-to-2 quantum cloning (quantum duplication) and 1-to-infinity cloning (classical measurement), we show that a fidelity value larger than 2/3 is required for successful quantum teleportation of coherent states. This value has not been reached experimentally so far.Comment: 4 pages, 1 figure, submitted to Phys. Rev.

Collective modes and correlations in one-component plasmas

The static and time-dependent potential and surface charge correlations in a plasma with a boundary are computed for different shapes of the boundary. The case of a spheroidal or spherical one-component plasma is studied in detail because experimental results are available for such systems. Also, since there is some knowlegde both experimental and theoretical about the electrostatic collective modes of these plasmas, the time-dependent correlations are computed using a method involving these modes.Comment: 20 pages, plain TeX, submitted to Phys. Rev.

The antidiabetic effects of a dry powder of dietary vegetable and fruit mixtures in diabetic db/db mice

We evaluated the antidiabetic effects of a mixed vegetable powder-formula I (MVP-FI), which is a dry powder mixture of over 65 kinds of vegetables and fruits, using the db/db type 2 diabetes mouse model. The db/db mice at 8-10 weeks of age were randomly divided into three groups: vehicle treatment, 1.575 g/kg MVP-FI treatment, and 3.15 g/kg MVP-FI treatment. During 12 days of treatment, we measured food intake and body weight changes, fasting blood glucose levels, and plasma lipid levels. Our results showed that the food intake and the body weight of MVP-FI-treated group were decreased gradually. Moreover, the fasting blood glucose level of the treated group was significantly dropped to a normal level comparable to that of the lean mice. Furthermore, we also found that the plasma triglyceride level in the treated group was dropped, whereas the high-density lipoprotein (HDL) level was increased and total cholesterol/HDL-cholesterol ratio was decreased. Taken together, these results suggest that the diabetic conditions of the db/db mice have been improved after 12 days treatment with MVP-FI. The antihyperglycemic and antiobese activities of the MVP-FI, as demonstrated in the present study, may have important clinical implications for improving the management of type 2 diabetic patients. © 2008 Yeung et al, publisher and licensee Dove Medical Press Ltd.published_or_final_versio

Can a falling tree make a noise in two forests at the same time?

It is a commonplace to claim that quantum mechanics supports the old idea that a tree falling in a forest makes no sound unless there is a listener present. In fact, this conclusion is far from obvious. Furthermore, if a tunnelling particle is observed in the barrier region, it collapses to a state in which it is no longer tunnelling. Does this imply that while tunnelling, the particle can not have any physical effects? I argue that this is not the case, and moreover, speculate that it may be possible for a particle to have effects on two spacelike separate apparatuses simultaneously. I discuss the measurable consequences of such a feat, and speculate about possible statistical tests which could distinguish this view of quantum mechanics from a ``corpuscular'' one. Brief remarks are made about an experiment underway at Toronto to investigate these issues.Comment: 9 pp, Latex, 3 figs, to appear in Proc. Obsc. Unr. Conf.; Fig 2 postscript repaired on 26.10.9