Inhibitory inefficiency and failures of intention activation: Age-related decline in the control of saccadic eye movements.

Young and older adults' control of saccadic eye movements was compared using an antisaccade task, which requires the inhibition of a reflexive saccade toward a peripheral onset cue followed by an intentional saccade in the opposite direction. In 2 experiments, an age-related decline was found in the suppression of reflexive eye movements, as indicated by an increased proportion of saccades toward the cue, and a longer time needed to initiate correct antisaccades. The results from Experiment 2 suggested that older adults' slower antisaccades may be explained partly in terms of increased failures to maintain the cue-action representation at a sufficient activation level. The results suggest that the notion of selective preservation with age of the ability to inhibit spatial responses does not apply to the active inhibition of prepotent spatial responses. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Studies on the self‐assembly of neat DBS and DBS/PPG organogels

The self‐assembly behavior of neat 1,3:2,4‐dibenzylidene‐D ‐sorbitol (DBS) and DBS/poly(propylene glycol) (PPG) organogels has been investigated by scanning electron microscopy, polarizing optical microscopy, and rheological measurements. DBS molecules are capable of self‐organizing into fibrils and exhibit the birefringent spherulitic textures during cooling from the melt. On the other hand, DBS can self‐assemble into a fibrillar network in PPG to produce organogels. DBS/PPG organogels also reveal a spherulite‐like morphology. When a small amount of DBS is dispersed into a PPG matrix, we find that the spherulite sizes are much smaller than those of neat DBS. This is because the dilution of DBS causes DBS to self‐assemble in PPG at a lower temperature. Therefore, more nucleation sites and smaller spherulite sizes are found in the DBS/PPG organogel system. The rheological measurements demonstrate that the elastic modulus (G′) in DBS/PPG organogels increases as the DBS concentration increases. However, the increase in G′ is less obvious, as the DBS content exceeds 3 wt %. suggesting that the DBS networks become saturated. Also, it is found that these organogels require a certain period of time to reach thermodynamic equilibrium, depending on DBS concentrations. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Refractive-index profiling of graded-index planar waveguides from effective indexes measured with different external refractive indexes

We extend the well-known inverse Wentzel-Kramer-Brillouin (WKB) method for refractive-index profiling of graded-index planar waveguides. We demonstrate, with numerical examples and experimental results, that the refractive-index profile of a graded-index planar waveguide can be calculated from effective indexes measured with different external refractive indexes. With this technique, single-mode and two-mode waveguides can be profiled easily to a good accuracy.     

Shallot and licorice constituent isoliquiritigenin arrests cell cycle progression and induces apoptosis through the induction of ATM/p53 and initiation of the mitochondrial system in human cervical carcinoma HeLa cells

This study is the first to investigate the anticancer effect of isoliquiritigenin (ISL) in human cervical carcinoma HeLa cells. The results reveal that ISL inhibits HeLa cells by blocking cell cycle progression in the G2/M phase and inducing apoptosis. Blockade of cell cycle is associated with increased activation of ataxia telangiectasia‐mutated (ATM). Activation of ATM by ISL phosphorylated p53 at Serine15, resulting in increased stability of p53 by decreasing p53 and murine double minute‐2 (MDM2) interaction. In addition, ISL‐mediated G2/M phase arrest was also associated with decreases in the amounts of cyclin B, cyclin A, cdc2, and cdc25C, and increases in the phosphorylation of Chk2, cdc25C, and cdc2. The specific ATM inhibitor caffeine significantly decreased ISL‐mediated G2/M arrest by inhibiting the phosphorylation of p53 (Serine15) and Chk2. ISL induced apoptotic cell death is associated with changes in the expression of Bax and Bak, decreasing levels of Bcl‐2 and Bcl‐X_L, and subsequently triggering mitochondrial apoptotic pathway. In addition, pretreatment of cells with caspase‐9 inhibitor blocked ISL‐induced apoptosis, indicating that caspase‐9 activation is involved in ISL‐mediated HeLa cell apoptosis. These findings suggest that ISL may be a promising chemopreventive agent against human uterine cervical cancer.     

Sub-nanosecond pulse-forming network on SiGe BiCMOS for UWB communications

A pulse-forming network (PFN) has been developed for ultra-wideband (UWB) communication systems. This PFN generates sub-nanosecond pulses at a pulse repetition frequency (PRF) of >500 MHz for high data-rate applications like wireless video streaming. To generate the pulses, the PFN performs two operations on an input data signal: it decreases the signal rise time, then it differentiates the signal. The differentiation circuit is a frequency-dependent negative-feedback system. The PFN is fabricated in SiGe BiCMOS with an active die size of less than 0.25 mm/sup 2/, and it requires 3.3-V 20-mA dc during operation. Measured performance is validated at 500-MHz PRF, achieving pulsewidth of 175 ps and pulse amplitude of 0.17 V. The PFN is also validated within a transmitter system that transmits Manchester coded pseudorandom bit sequence. Measured effective isotropic radiated power of the transmitter shows that the PFN output power is sufficient to meet the Federal Communications Commission's emission limits, thus eliminating the need of amplification before transmission.     

Thyroxine administration to infants of less than 30 weeks gestational age decreases plasma tri-iodothyronine concentrations

OBJECTIVE: To investigate the effect on thyroid hormone metabolism of the administration of thyroxine to very preterm infants. DESIGN AND METHODS: Two hundred infants of less than 30 weeks gestation were enrolled into a randomized, double-blind, placebo-controlled trial. Thyroxine (T4) (at a fixed daily dose of 8 microg/kg birthweight) or placebo was started 12-24h after birth and discontinued 6 weeks later. Plasma concentrations of T4, tri-iodothyronine (T3), reverse T3 (rT3), TSH, and thyroxine-binding globulin were measured weekly during trial medication and 2 weeks thereafter. RESULTS: The T4 and the placebo group each comprised 100 infants. Antenatal, perinatal, and postnatal clinical characteristics were comparable in both groups. T4 and rT3 were significantly increased in the T4 group. TSH concentrations were depressed in the T4 group and T3 was significantly decreased, probably as a result of TSH depression. The T4/T3 and T4/rT3 ratios differed significantly between the two study groups. CONCLUSIONS: Daily T4 administration during the first 6 weeks after birth to infants of less than 30 weeks gestation prevents hypothyroxinemia, but decreases plasma T3 concentrations. Our finding possibly implies that very preterm infants should receive supplements of both T4 and T3.     

Analysis of two parallel long-period fiber gratings

A wavelength-selective coupler constructed with two parallel identical uniform long-period fiber gratings (LPFGs) is analyzed by the coupled-mode theory. The effects of introducing a longitudinal offset distance between the two gratings on the transmission characteristics of the coupler are discussed and the conditions for achieving a 100% coupling efficiency are highlighted. It is found that 100% coupling can be achieved with a practical grating length by using a proper grating design and a suitable index-matching surrounding medium. The theoretical results agree well with the experimental data.     

Inhibition from nonword primes in lexical decision reexamined: The critical influence of instructions.

Compound-cue theory predicts that lexical decisions are slower to word targets preceded by a nonword than to word targets preceded by an unrelated word. This nonword-prime inhibition effect is not predicted by spreading-activation theories. R. Ratcliff and G. McKoon (1995) obtained nonword-prime inhibition, whereas T. R McNamara (1994b) failed to obtain it. In the present study, for both a 200-ms and 350-ms prime-target stimulus onset asynchrony, nonword-prime inhibition was obtained for participants who, as in Ratcliff and McKoon's research, received instructions that mentioned that prime and target could be related. No nonword-prime inhibition was found for participants who, as in McNamara's research, received instructions that did not mention the possibility of a prime-target relation. Neither compound cue nor spreading activation can explain this pattern. The possibility that nonword-prime inhibition results from response competition is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Abatement of heavy metals and softening of hard water by the CoAlPO4‐5/polysulfone membrane

To improve the membrane, if CoAlPO₄‐5 was appropriately added, it could increase the rejection rate of metal ions compared with the PSf membrane. Besides, penetration rate would also increase, and the pressure applied could be lowered when the improved membrane was used. The optimum amount of CoAlPO₄‐5 added for Co : Al : P = 0.1 : 0.92 : 1.0 is about 5 wt %, while for the Co : Al : P = 0.08 : 0.93 : 1.0, this optimum value would shift toward a higher wt % because the latter has less active sites per unit weight of CoAlPO₄‐5. The hydrated radius of metal ion had great influence on the rejection rate. The larger the radius, for example, that of the +3 valence cations, the higher the rejection rate would exhibit, and the rate for Cd²⁺ was much lower because its radius was the smallest one. Moreover, although incompatibility existed in the improved membrane and the variation of applied pressure was limited, durability of this membrane under the operating conditions was good. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2768–2773, 2001