Search Results - (Author, Cooperation:P. Cheung)

2018-01-23

The American Society for Microbiology (ASM)

0019-9567

1098-5522

Medicine

2012-03-09

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Animals ; Carrier Proteins/genetics/metabolism ; Cell Cycle ; Cell Line ; Chromatin/genetics/metabolism ; Congenital Microtia ; Crystallography, X-Ray ; *DNA Replication/genetics ; Disease Models, Animal ; Dwarfism/genetics/metabolism ; Ear/abnormalities ; Growth Disorders/genetics/*metabolism ; Histones/*chemistry/genetics/*metabolism ; Humans ; Lysine/*metabolism ; Methylation ; Micrognathism/genetics/*metabolism ; Models, Molecular ; Origin Recognition Complex/*chemistry/genetics/*metabolism ; Patella/abnormalities/metabolism ; Protein Structure, Tertiary ; Replication Origin ; Zebrafish ; Zebrafish Proteins/genetics/metabolism

2018-05-19

MDPI Publishing

1661-7827

1660-4601

Energy, Environment Protection, Nuclear Power Engineering

Medicine

1089-7674

AIP Digital Archive

Physics

This is the second of two papers comprising a theoretical and observational study of new, altitude-resolved, observations at Arecibo of Langmuir turbulence induced in the ionosphere by a new, more powerful, high frequency heater operated at very low duty cycles. Altitude resolution of 150 m in incoherent scatter radar spectra is made possible by the coded-long-pulse method. Here we present the first observation at Arecibo of the well-developed parametric decay instability and the Langmuir decay instability cascade features in the Thomson scatter radar power spectrum, of the plasma line, at the unmodified matching altitudes under near-cold start conditions. The dependence of the plasma line spectra on altitude, pump power, and density scale length have been studied. The temporal growth and saturation of the spectra during heating and the decay of the spectra in the afterglow of heating has also been studied in detail. Comparisons are made here with the theoretical predictions of the companion paper I [DuBois et al., Phys. Plasmas 8, 791 (2001)]. From these comparisons and a comparison with recent observations at both Arecibo and Tromsø, we conclude that all the predictions of modern Langmuir turbulence theory for the radar spectral signatures of the turbulence in a smooth ionosphere have now been verified. © 2001 American Institute of Physics.

Electronic Resource

1089-7666

AIP Digital Archive

Physics

The nonlinear evolution of the electron-beam–plasma instability is investigated experimentally in two stages in a large, uniform, and unmagnetized plasma. In the initial stage, the beam-driven, linearly unstable wave saturates due to changes in the beam distribution. At sufficiently intense wave amplitude, the instability evolves into a second stage where nonlinear effects due to the ponderomotive force dominate and the wave rapidly undergoes spatial collapse and contracts to very small scale lengths in the coexisting density cavity. The transverse contraction of the wave agrees with theories on three-dimensional Langmuir collapse. This second stage can further be classified according to the beam strength. At low beam density, a single collapsing wave packet is formed and the electron beam decouples from the collapsing wave and propagates relatively unperturbed through the plasma. At higher beam density, multiple field spikes are formed both along and across the beam path and the beam distribution is broadened through successive scattering by the multiple intense field spikes.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

We consider the effective nonlinear susceptibility tensor χ for third harmonic generation (THG) in a nonlinear composite medium in which the components may have nonvanishing second- and third-order nonlinear susceptibilities. We derive an expression for this susceptibility in terms of the positional-dependent second- and third-order susceptibilities within the composite, as well as several factors which describe the local field effect in a corresponding linear medium. We consider both the THG due to the presence of THG susceptibility in the components, and the induced THG due to the presence of second-order nonlinear susceptibilities in the components. The resulting expression can be used to calculate both local field and percolation effects on χ in a wide range of geometries. The general expression reduces to a simple result in the dilute limit, which is similar to that previously derived. An effective medium approximation, which is applicable to the whole range of concentration, is proposed for both the effective second and third harmonic susceptibilities. Results obtained from the general expression and the effective medium approximation are found to be in good agreement with those obtained by numerical simulations for a model system of nonlinear composites consisting of a nonlinear metallic component and a linear insulating component. © 1998 American Institute of Physics.

Electronic Resource

1460-9568

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

The synthesis of the intracellular messenger, cyclic GMP, is catalysed by particulate or soluble guanylyl cyclase (sGCY). sGCY is activated by nitric oxide, a compound with putative neurotransmitter functions, especially in long-term potentiation. Hybridization histochemistry with a probe complementary to the rat lung large (α1) subunit was used to assess the exact localization of sGCY mRNA in the rat brain. Many cells in the olfactory bulb contained sGCY mRNA. In the whole cerebral cortex, sGCY mRNA was found in all layers, with a predominance in layers II - III. A similar pattern was found in the olfactory tuberculum, in continuation with the piriform cortex and the cortical amygdaloid nucleus. All parts of the striatum expressed sGCY mRNA. sGCY mRNA was also found in the habenula medialis, in the pinealis in some diencephalic nuclei, and in the granule cell layers of the cerebellum. This study provides a description of the normal anatomy of sGCY gene expression in the rat forebrain as a basis for the study of the modulation of expression after physiological and pharmacological manipulations.

Electronic Resource

1365-2761

Blackwell Publishing Journal Backfiles 1879-2005

Biology

Medicine

Electronic Resource

1365-2761

Blackwell Publishing Journal Backfiles 1879-2005

Biology

Medicine

Electronic Resource

1365-2761

Blackwell Publishing Journal Backfiles 1879-2005

Biology

Medicine

Electronic Resource

1365-2761

Blackwell Publishing Journal Backfiles 1879-2005

Biology

Medicine

Abstract. A normally free-living hymenostomatid ciliate was found to be the cause of heavy infections of gills, viscera and body muscle in Atlantic and Pacific marine fishes kept in the New York Aquarium. Of special interest is the fact that the parasites, usually with food vacuoles filled with blood cells and cellular debris, caused extensive damage to the body muscle; the other infected organs showed no characteristic tissue reactions. The immediate cause of death is attributed to the exceptional load of the parasite on the gills, thus interfering with normal respiratory function.The ciliate, isolated from a recent outbreak, is described in detail, and shows many characteristics of Uronema marinum Dujardin, a species that has been reported as free-living in salt water; the form reported here differs from the type and other members included in this species, by the presence of less than three rows of bipolar meridians. This facultative parasite is described in detail and compared with other genera.

Electronic Resource

1365-2761

Blackwell Publishing Journal Backfiles 1879-2005

Biology

Medicine

Abstract. Trophonts of Cryptocaryon irritans Brown from infected three-spot damselfish, Dascyllus trimaculatus Ruppell, were kept at temperatures ranging from 7 to 37°C to observe encystment and development of the tomites. At 30, 25 and 20°C, the percentage of trophonts that had encysted in 16 h were 70, 77 and 64% respectively; at 37°C, 44% encysted and at 7°C only 10% had encysted.The optimum temperature for excystment was 30°C; 50% excysted in 5 days and 100% in 7 days. At 25°C, 60% of the tomites started to excyst on the eighth day, and 70% on the ninth day. At 20°C, 10% started to excyst on the ninth day, reaching 40% on the tenth day. No excystment occurred at 37 and 7°C.Newly encysted tomonts were placed in various dilutions of sea water (31 %0) and kept at temperatures ranging from 7 to 37°C. Low salinities, i.e. 16%0 and lower caused tomonts to rupture. At 37, 20 and 7°C, 35% of the tomonts started to rupture immediately in 50% sea water, while at 30 and 25 C, 30% of the tomonts ruptured in 25% seawater. However, none of the cysts developed normally at these dilutions. The percentage rupturing increased with decreasing salinity.

Electronic Resource

0003-9861

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Biology

Chemistry and Pharmacology

Physics

Electronic Resource

0003-2670

CRISP ; Immunoassay ; Multi-clonal immunoassay ; Pattern recognition ; Triazine herbicides

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Chemistry and Pharmacology

Electronic Resource

0021-9673

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Chemistry and Pharmacology

Electronic Resource

0006-291X

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Biology

Chemistry and Pharmacology

Physics

Electronic Resource

0009-9120

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Medicine

Electronic Resource

0009-9120

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Medicine

Electronic Resource

0009-9120

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Medicine

Electronic Resource

1432-1793

Springer Online Journal Archives 1860-2000

Biology

Abstract A new method for collecting barnacle cement in the liquid state is described. This permits studies on the transformation of cement from liquid to solid states not heretofore possible. Preliminary analyses showed that polymerization, i.e., the in vitro change from a clear liquid to an opaque solid mass is not affected by temperatures ranging from-10° to 45°C, by diluting with distilled water up to two-fold, or by treating with selective enzymes; some chemical inhibitors induce the formation of a white precipitate, possibly indicating denaturation of the protein. It is concluded that the liquid cement contains all the necessary components for self-assembly, progressively changing from a clear liquid to an opaque rubbery insoluble mass. The polymerization process is time-dependent and requires no exogenous catalyst. A mechanism that may be involved in the adhesion process of the barnacle is suggested.

Electronic Resource