Extended C-band tunable multi-channel InP-based coherent receiver PICs.

Fully integrated monolithic, multi-channel InP-based coherent receiver PICs and transceiver modules with extended C-band tunability are described. These PICs operate at 33 and 44 Gbaud per channel under dual polarization (DP) 16-QAM modulation. Fourteen-channel monolithic InP receiver PICs show integration and data rate scaling capability to operate at 44 Gbaud under DP 16-QAM modulation for combined 4.9 Tb/s total capacity. Six channel simultaneous operation of a commercial transceiver module at 33 Gbaud is demonstrated for a variety of modulation formats including DP 16-QAM for >1.2Tbit/s aggregate data capacity.

1.12 Tb/s superchannel coherent PM-QPSK InP transmitter photonic integrated circuit (PIC).

In this work, a 10-wavelength, polarization-multiplexed, monolithically integrated InP coherent QPSK transmitter PIC is demonstrated to operate at 112 Gb/sec per wavelength and total chip superchannel bandwidth of 1.12 Tb/s. This demonstration suggests that increasing data capacity to multi-Tb/s per chip is possible and likely in the future.

N-terminal and C-terminal plasma membrane anchoring modulate differently agonist-induced activation of cytosolic phospholipase A2.

The 85 kDa cytosolic phospholipase A2 (cPLA2) plays a key role in liberating arachidonic acid from the sn-2 position of membrane phospholipids. When activated by extracellular stimuli, cPLA2 undergoes calcium-dependent translocation from cytosol to membrane sites which are still a matter of debate. In order to evaluate the effect of plasma membrane association on cPLA2 activation, we constructed chimeras of cPLA2 constitutively targeted to the plasma membrane by the N-terminal targeting sequence of the protein tyrosine kinase Lck (Lck-cPLA2) or the C-terminal targeting signal of K-Ras4B (cPLA2-Ras). Constitutive expression of these chimeras in Chinese hamster ovary cells overproducing the alpha2B adrenergic receptor (CHO-2B cells) did not affect the basal release of [3H]arachidonic acid, indicating that constitutive association of cPLA2 with cellular membranes did not ensure the hydrolysis of membrane phospholipids. However, Lck-cPLA2 increased [3H]arachidonic acid release in response to receptor stimulation and to increased intracellular calcium, whereas cPLA2-Ras inhibited it, compared with parental CHO-2B cells and CHO-2B cells producing comparable amounts of recombinant wild-type cPLA2. The lack of stimulation of cPLA2-Ras was not due to a decreased enzymatic activity as measured using an exogenous substrate, or to a decreased phosphorylation of the protein. These results show that the plasma membrane is a suitable site for cPLA2 activation when orientated correctly.

Positive and negative hepatic regulation of the human type II phospholipase A2 gene.

To identify the elements which regulate the liver transcription of the human type II phospholipase A2 gene and its stimulation by interleukin 6, the 5' flanking region from -1614 to +806 and several 3' and 5' deleted fragments have been analyzed in CAT assays. Negative regulatory elements have been located in the regions -1614 to -326 and +20 to +806. The fragment -326 to +20 contains the main elements required for the transcription as well as for the stimulation by interleukin 6. Footprinting assays have been performed on this region and showed four protected elements, A [-35;-6], B [-125;-86], C [-209;-176], and D [-247;-211]. Deletion of element D enhanced the transcription of the reporter gene 10.5-fold compared to the [-326;+20]-CAT construct. Further deletions up to position -87 which removed both the elements B and C or the substitution of element C by a nonspecific sequence lowered the promoter activity to 23% and 70% of the control, respectively. These results indicate that element C binds positive regulatory factors and element D binds a negative regulatory factor. Furthermore, stimulation by interleukin 6 is lost when element C is substituted or deleted. As shown by the footprinting and band shift assays, the transcription factors C/EBP alpha and C/EBP beta can bind to elements C and D but the dissociation constant (Kd) of C/EBP alpha is 10 times lower for element C (0.6 nM) than for element D (5.8 nM). Band shift experiments using rat liver nuclear extracts showed that element C formed four heat stable complexes, some of which could be supershifted by anti C/EBP alpha antibodies. The binding of C/EBP factors to element C was confirmed by competition with previously described oligonucleotide and nucleotide substitution of element C. Band shift experiments using rat liver nuclear extracts showed that element D formed one major DNA-protein complex. This complex could be competed out by oligonucleotides containing a cAMP responsive element (CRE) but not by oligonucleotides containing the binding site of C/EBP. However, anti-CREB antibodies did not supershift this complex. Methylation interference experiments showed the involvement of a G nucleotide upstream to the sequence homologous to CRE in the binding of the hepatic nuclear factors.(ABSTRACT TRUNCATED AT 400 WORDS)

Optical switching in cadmium telluride using a light-induced electrode nonlinearity.

An optically controlled buildup and erasure of an electric field under the negative electrode in CdTe:In is reviewed both experimentally and theoretically. Below-band-gap impurity-absorbed light (850-920 nm) results in the buildup of a region of very high electric field (E ~ 20 kV/cm) under the negative electrode. Illumination at wavelengths above or near the band gap (800-840 nm) can erase the high electric fields. The writing and erasure of the field follow the illumination pattern and can therefore be used, when combined with the electro-optic or electroabsorption effects, for one- and two-dimensional infrared spatial modulators with signal beams in the 900-1500-nm range. Switching times are a few hundred nanoseconds at moderate intensity levels (milliwatts per square centimeter). We demonstrate a one-dimensional latching array with 170 line pairs/cm resolution, submicrosecond response, and 12-pJ/pixel switching energy. We also demonstrate a two-dimensional infrared spatial light modulator, similar to the PRZ, which uses this effect. The optically controlled electric fields are large enough for sizable Franz-Keldysh effects, and we demonstrate these effects in both one- and two-dimensional devices.

Infrared nonlinear neurons using the field shielding effect in CdTe.

We report on a novel IR neuron device that utilizes the field shielding effect in CdTe:In, wherein optical activation beams create an intensity dependent space-charge field. The induced electrooptic birefringence or index change is used in a neuron-type configuration to demonstrate a high sensitivity nonlinear saturated response with an absorption loss of

Opto-optical switching in the infrared using CdTe.

Opto-optical switching of a 1.06-microm signal beam by another 1.06-microm control beam has been observed in CdTe:In. The switching is caused by the photocharge created by the control beam and the resultant electric-field shielding. This effect can be switched in microseconds and takes advantage of the high figure of merit (n(3)r/) of CdTe.

Enhanced two-beam mixing gain in photorefractive GaAs using alternating electric fields.

Enhanced two-beam mixing amplification at a wavelength of 1.06 mum obtained by using sinusoidal electrical fields at 7.7 MHz is reported. The peak measured gains are comparable with dc field enhanced gain but with smaller rms fields. At grating wavelengths >3 mum the ac enhanced gain is considerably higher than the dc enhanced gain. Uniform alternating electric fields are much easier to establish inside the material and result in a much more stable output than dc fields.

[Probable conditioned prostaglandin deficiency in cows with ovarian cysts (author's transl)]. / possibilité d'une carence conditionnée en prostaglandines chez les vaches porteuses de kystes ovariens.

Blood and ovaries have been collected monthly for one year from 1358 cows at the slaughter-house. 4.4% of the cows presented cystic follicle ovaries (follicle with a diameter greater than or equal to 25 mm) and 5.7% presented cystic corpus luteum (internal cavity with a diameter greater than or equal to 10 mm). Analysis of fatty acid composition of red blood cells lipids has shown that in cows with cystic follicles (P less than 0.001) and in cows with cystic corpus luteum (P less than 0.01), the proportions of omega 3 family polyunsaturated fatty acids were higher than in normal cow. The sigma omega 3/ sigma omega 6 ratio was also higher (P less than 0.001) for cows with both types of ovarian cysts, particularly in spring, summer and autumn. An alimentary etiology of ovarian cysts pathogeny could be an increased intake of these fatty acids which are more abundant in young grass. The omega 3 polyunsaturated fatty acids are known to be inhibitors of the synthesis of PgF2 alpha which is involved in ovulation and luteolysis.