Cubic sinusoidal phase mask: Another choice to extend the depth of field of incoherent imaging system

Wave-front coding is a well known technique used to extend the depth of field of incoherent imaging system. The core of this technique lies in the design of suitable phase masks, among which the most important one is the cubic phase mask suggested by Dowski and Cathey (1995) [1]. In this paper, we propose a new type called cubic sinusoidal phase mask which is generated by combing the cubic one and another component having the sinusoidal form. Numerical evaluations and real experimental results demonstrate that the composite phase mask is superior to the original cubic phase mask with parameters optimized and provides another choice to achieve the goal of depth extension. (C) 2009 Elsevier Ltd. All rights reserved.

The effects of the last glacial paleo-aeolian sands on desertification in northern China

IEECAS SKLLQG

Use of Zr/Rb ratios in Chinese loess sequences to trace paleo-winter monsoon winds strength

IEECAS SKLLQG

Micronuclei induction in human lymphocytes induced by carbon ions exposion along the penetrate depth of ions in water

Here we used cytokinesis-block micronucleus assay to measure the biological response along the penetrate depth of ions in water in human lymphocytes exposed to 100 MeV/u incident carbon ions in vitro. Polyethylene shielding was used to change the penetration depth of ions in water. A quantitative biological response curve was generated for micronuclei induction. The results showed a marked increase with the penetrate depth of ions in water in the micronuclei formation, which was consistent with a linearenergy- transfer dependent increase in biological effectiveness. The dose–response relationship for MN information was different at different penetrate depth of ions in water, at the 6 and 11.2 mm penetrate depth of ions in water, the dose–response relationships for the micronucleus frequencies induced by carbon ions irradiation were linear; while it was power function at 17.1 mm penetrate depth.

Rotating wheel filter design and optimization for a uniform depth dose distribution in heavy ion therapy

Treatment planning of heavy-ion radiotherapy involves predictive calculation of not only the physical dose but also the biological dose in a patient body. The goal in designing beam-modulating devices for heavy ion therapy is to achieve uniform biological effects across the spread-out Bragg peak (SOBP). To achieve this, a mathematical model of Bragg peak movement is presented. The parameters of this model have been resolved with Monte Carlo method. And a rotating wheel filter is designed basing on the velocity of the Bragg peak movement.

Relationship between precipitation and the infiltration depth over the middle and lower reaches of the Yellow River and Yangtze-Huaihe River Valley

National Natural Science Foundation of China [40701021, 40625002, 40331013]; National Knowledge Innovation Program of Chinese Academy of Sciences [KZCX2-YW-315-2]

The variation of upper ocean structure and paleoproductivity in the Kuroshio source region during the last 200 kyr

A core from the source region of the Kuroshio warm current (east of the Luzon Island) was analyzed using several proxies in order to study the variability of the Western Pacific Warm Pool (WPWP) during the last two glacial-interglacial cycles. Primary productivity (PP) variations were deduced from variations in the coccolith flora. Primary productivity was higher during glacial periods (the end of Marine Isotope Stage [MIS] 3, some periods in MIS 2 and 6), and decreased during interglacial periods (MIS 7, MIS Se and probably MIS 5c-5d), with the lowest PP in MIS 5e. variations in the delta C-13 difference in benthic and bulk carbonate, thus in the vertical gradient of delta C-13 in dissolved inorganic carbon (Delta delta C-13(c). (wuellerstorfi-N. dutertrei) and Delta delta C-13(c.) (wuellerstorfi-coccolith)) Coincided With the PP Changes, showing that export productivity was low during interglacial periods (MIS 7, MIS 5e and Holocene) and high during glacial periods (MIS 6, probably MIS 5c-5d, late MIS 4 and late MIS 3). Comparison of foraminiferal carbonate dissolution indicators and PP changes reveals that nannofossil assemblage in core Ph05-5 is not sensitive to carbonate dissolution intensity. The depth of the thermocline (DOT) was estimated from planktonic forminiferal assemblages, and was relatively greater during interglacial periods (MIS 7, MIS 5e, probably MIS 5c and Holocene) than during glacials (middle MIS 6, probably MIS 5b and 5d, some periods in MIS 4, MIS 3 and MIS 2). Good coherence between the paleoproductivity records and the DOT suggests that the DOT changes could be the primary control factor in changes of paleoproductivity, and the glacial high productivity in the Kuroshio source region could be associated with a global increase of nutrient concentration in the intermediate waters that upwelled into the photic zone. The low CO2 values derived for intervals of high productivity and a relatively shallow DOT suggest that the changes in biological productivity and DOT in the equatorial Pacific could have modified atmospheric CO2 concentrations. High Sea Surface Temperatures (SSTs) during the warm MIS 5e in combination with intensified monsoonal rain fall could have resulted in a more intense stratification of the upper waters, resulting in low nutrient supply to the surface waters and a resulting decrease in productivity. (C) 2010 Elsevier B.V. All rights reserved.

Influence of mean water depth and a subsurface sandbar on the onset and strength of wave breaking

Wave breaking in the open ocean and coastal zones remains an intriguing yet incompletely understood process, with a strong observed association with wave groups. Recent numerical study of the evolution of fully nonlinear, two-dimensional deep water wave groups identified a robust threshold of a diagnostic growth-rate parameter that separated nonlinear wave groups that evolved to breaking from those that evolved with recurrence. This paper investigates whether these deep water wave-breaking results apply more generally, particularly in finite-water-depth conditions. For unforced nonlinear wave groups in intermediate water depths over a flat bottom, it was found that the upper bound of the diagnostic growth-rate threshold parameter established for deep water wave groups is also applicable in intermediate water depths, given by k(0) h greater than or equal to 2, where k(0) is the mean carrier wavenumber and h is the mean depth. For breaking onset over an idealized circular arc sandbar located on an otherwise flat, intermediate-depth (k(0) h greater than or equal to 2) environment, the deep water breaking diagnostic growth rate was found to be applicable provided that the height of the sandbar is less than one-quarter of the ambient mean water depth. Thus, for this range of intermediate-depth conditions, these two classes of bottom topography modify only marginally the diagnostic growth rate found for deep water waves. However, when intermediate-depth wave groups ( k(0) h greater than or equal to 2) shoal over a sandbar whose height exceeds one-half of the ambient water depth, the waves can steepen significantly without breaking. In such cases, the breaking threshold level and the maximum of the diagnostic growth rate increase systematically with the height of the sandbar. Also, the dimensions and position of the sandbar influenced the evolution and breaking threshold of wave groups. For sufficiently high sandbars, the effects of bottom topography can induce additional nonlinearity into the wave field geometry and associated dynamics that modifies the otherwise robust deep water breaking-threshold results.