Biomedical subjects
Publications and source records attributed to S H Tao.
We propose a design for a phase mask for generating an optical vortex with suppressed sidelobes in the focal plane where the radius of the intensity ring is variable. A radial modulation added to conventional phase mask exp(iltheta) projects the light diffracted from different annular zones into a single intensity ring in the focal plane.
Sequence analysis has proved that decamer nucleotides, used as primers of RAPD (random amplified polymorphic DNA), differ with each other greatly in number of annealing sites in the Arabidopsis thaliana genome. It is called the 'primer bias' by the authors. The biased primers produce a highly variable number of amplicons by polymerase chain reaction (PCR). The number of amplicons is proved to correlate with the number of annealing sites. Therefore, a statistical method is proposed for selecting efficient primers based on the primer bias in the genomic sequence. The method was tested by experiment in A. thaliana genome, and the results demonstrate that the method outperforms routine methods and can substantially increase the efficiency of RAPD methodologies. We also proved that the expressed sequence tags (ESTs) show a highly coincident bias pattern with that of the whole genomic sequence, and can therefore be used to assess efficiencies of primers for species whose genomic sequence data are currently unknown.
We propose a new design for fabrication of a highly power-efficient double axicon to generate self-imaged three-dimensional intensity voids along the propagation of a beam. The conventional conical structure of an axicon is modified and shaped like an axiconlike structure with a double-gradient surface profile. The gradient conical surfaces generate Bessel beams with varying radial wave vectors that are superimposed and interfere to generate a sequence of three-dimensional intensity voids. The proposed element was fabricated using electron-beam lithography, and experimental verification of the design is reported.
We propose a highly efficient approach to generating multihelix beams that contain more than one helical mode, and the power distribution over helical modes is adjustable. A multihelix beam embedded with three collinear helical modes is demonstrated by use of a spatial light modulator.
Higher-order Bessel beams have been demonstrated to have the ability to trap and rotate low- and high-index particles simultaneously [Phys. Rev. A 66, 063402 (2002)]. The rotation and trapping is caused by the presence of orbital angular momentum arising from its azimuthal phase variation (that changes at integer multiples of 2pi) and the concentric rings of the Bessel mode. We demonstrate for the first time to our knowledge a branch from the family of higher-order Bessel beams that has fractional azimuthal variation at its beam axis. This new family of laser beams has the ability to perform dynamic optical manipulation with dynamic control of a spatial light modulator. Furthermore, we take the opportunity to explore the propagation characteristics of higher-order Bessel beams for which the azimuthal phase changes at noninteger multiples of 2pi.
Three approaches are proposed in this study for detecting or estimating linkage disequilibrium between a polymorphic marker locus and a locus affecting quantitative genetic variation using the sample from random mating populations. It is shown that the disequilibrium over a wide range of circumstances may be detected with a power of 80% by using phenotypic records and marker genotypes of a few hundred individuals. Comparison of ANOVA and regression methods in this article to the transmission disequilibrium test (TDT) shows that, given the genetic variance explained by the trait locus, the power of TDT depends on the trait allele frequency, whereas the power of ANOVA and regression analyses is relatively independent from the allelic frequency. The TDT method is more powerful when the trait allele frequency is low, but much less powerful when it is high. The likelihood analysis provides reliable estimation of the model parameters when the QTL variance is at least 10% of the phenotypic variance and the sample size of a few hundred is used. Potential use of these estimates in mapping the trait locus is also discussed.
Germanium-containing dietary supplements became popular in the 1970s in Japan and later in other countries, as elixirs for certain diseases (e.g., cancer and AIDS). Germanium is not an essential element. Its acute toxicity is low. However, at least 31 reported human cases linked prolonged intake of germanium products with renal failure and even death. Signs of kidney dysfunction, kidney tubular degeneration, and germanium accumulation were observed. Other adverse effects were anemia, muscle weakness, and peripheral neuropathy. Recovery of renal function is slow and incomplete even long after germanium intake was stopped. The total dose of ingested germanium (as dioxide, carboxyethyl germanium sesquioxide, germanium-lactate-citrate, or unspecified forms) varied from 15 to over 300 g; the exposure duration varied from 2 to 36 months. In laboratory animals, elevated germanium in tissues and impaired kidney and liver function were observed in a life-time drinking water (5 ppm germanium) study. Other toxicities associated with ingested germanium products in human cases were also demonstrated in animal studies with germanium dioxide and sometimes other germanium compounds. Based on the evidence of persistent renal toxicity associated with germanium dioxide, the lack of conclusive findings of differential nephrotoxicity of organic germanium compounds, and the possibility of contamination of the organic germanium products with inorganic germanium, it is clear that germanium products present a potential human health hazard.
Many cadmium-contaminated environments contain high levels of zinc. The effects of plant Zn and plant species on plant Cd bioavailability were tested in Japanese quail fed lettuce and spinach. Four groups of birds received 10% of their diets as lettuce or spinach leaves intrinsically labeled with 109Cd and containing low or high intrinsic Zn. Two other groups were fed control diets containing 109Cd as CdSO4 and low or high Zn as ZnCO3. Cadmium concentrations in diets ranged from 0.857 to 1.05 micrograms/g dry wt. Zinc concentrations in low-Zn diets ranged from 21.2 to 22.8, and in high-Zn diets from 56.0 to 63.3 micrograms/g dry wt. Increased lettuce and spinach Zn decreased plant Cd retention in kidney, liver, and jejunum-ileum of Japanese quail. Spinach Cd was less absorbed than lettuce Cd at both Zn levels. Inorganic Zn produced a lesser decrease in Cd retention in kidney, liver, and jejunum-ileum than did plant Zn. We conclude that (1) crops that transport Zn and Cd readily into edible tissues show lower Cd bioavailability when grown in Zn-Cd contaminated environments than in Cd-only polluted sites, (2) plant species differ in Cd bioavailability for identical concentrations of Zn and Cd in edible tissues, and (3) toxicological studies with animals exposed to Cd salts and Zn supplements do not assess Cd bioavailability of Zn-Cd contaminated crops.
Procedures for preparing myo-inositol bis-, tris-, tetrakis-, and pentakisphosphates from sodium phytate were established. Hydrolysis was achieved by autoclaving or enzymatic treatment; the inositol phosphates were separated by anion-exchange chromatography and were identified by fast atom bombardment-mass spectrometry. Enzymatic hydrolysis was more specific than autoclaving for isomer formation, whereas autoclaving was more efficient for producing the bis- and trisphosphates, which did not accumulate in significant amounts under the conditions of enzymatic hydrolysis. Sodium salts of the inositol phosphates were more powdery and less hygroscopic than the potassium salts. The procedures were satisfactory for producing gram quantities of each inositol phosphate, amounts adequate for animal studies of effects on mineral bioavailability.
Experiments with young Japanese quail were conducted to determine whether combined moderate deficiencies of zinc, iron and copper would cause greater uptake and tissue retention of cadmium than the single deficiencies. Birds were fed the experimental diets containing 62 ppb cadmium from hatching to 16 days of age. On day 9 each bird received a dose of 109CdCl2 in its diet. On day 10, the duodenal and jejunal-ileal tissues contained large amounts of cadmium, and there were many significant effects of treatment on cadmium-109 retention in the livers and kidneys. At day 16, zinc deficiency caused increased cadmium in the liver, whereas iron and copper deficiencies each caused increased cadmium in the kidneys. Combined deficiencies had little or no greater effect than single deficiencies and in some cases the combined effect was less than that of a single deficiency.
Studies were conducted to determine the effect of age on magnesium requirement and whether high dietary magnesium during the first 7 days of life would protect against subsequent magnesium deficiency. Day-old Japanese quail were fed a casein-gelatin diet containing either 300 (requirement) or 600 ppm Mg. Beginning on day 7, half of the birds in each group received either 160 (deficient) or 300 ppm Mg. In birds fed the requirement level during week 1 followed by the deficient diet, hemoglobin decreased on day 10, reaching the lowest value on day 14. Other adverse effects included mortality; slightly reduced growth rate; elevated iron in the liver, spleen, and tibia; decreased tibia magnesium; and increased spleen weight. Higher dietary magnesium (600 ppm) during week 1 prevented deficiency when 160 ppm Mg was fed in week 2; however, tibia magnesium was lower than that in birds fed 300 ppm Mg throughout. The protection may be related to reutilization of skeletal magnesium, which was elevated on day 7. In this and another experiment, birds initially fed 300 ppm Mg followed by 160 ppm (7-28 days) or 125 ppm Mg (14-28 days) had normal hemoglobin values at 21 and 28 days. These experiments showed that magnesium requirement decreased as quail aged (up to 4 weeks) and that a high magnesium diet (600 ppm) fed through days 0-7 protected against subsequent dietary inadequacy.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Administration of adrenaline to an isolated rat hindlimb preparation rapidly decreased muscle phosphorylase phosphatase (EC 3.1.3.17) activity and increased heat-stable and trypsin-labile phosphatase inhibitor activity. This was associated with increased tissue cyclic AMP concentrations, phosphorylase (EC 2.4.1.1) activation and glycogen synthase (EC 2.4.1.11) inactivation.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.