ABSTRACT
In the last few decades, there has been much progress on low loss waveguides, very efficient photon-number detectors and nonlinear processes. Engineered sum-frequency conversion is now at a stage where it allows operation on arbitrary temporal broadband modes, thus making the spectral degree of freedom accessible for information coding. Hereby the information is often encoded into the temporal modes of a single photon. Here, we analyse the prospect of using multi-photon states or squeezed states in different temporal modes based on integrated optics devices. We describe an analogy between mode-selective sum-frequency conversion and a network of spatial beam splitters. Furthermore, we analyse the limits on the achievable squeezing in waveguides with current technology and the loss limits in the conversion process.This article is part of the themed issue 'Quantum technology for the 21st century'.
ABSTRACT
We report the experimental point-by-point sampling of the Wigner function for nonclassical states created in an ultrafast pulsed type-II parametric down-conversion source. We use a loss-tolerant time-multiplexed detector based on a fiber-optical setup and a pair of photon-number-resolving avalanche photodiodes. By capitalizing on an expedient data-pattern tomography, we assess the properties of the light states with outstanding accuracy. The method allows us to reliably infer the squeezing of genuine two-mode states without any phase reference.
ABSTRACT
We report on the implementation of a time-multiplexed click detection scheme to probe quantum correlations between different spatial optical modes. We demonstrate that such measurement setups can uncover nonclassical correlations in multimode light fields even if the single mode reductions are purely classical. The nonclassical character of correlated photon pairs, generated by a parametric down-conversion, is immediately measurable employing the theory of click counting instead of low-intensity approximations with photoelectric detection models. The analysis is based on second- and higher-order moments, which are directly retrieved from the measured click statistics, for relatively high mean photon numbers. No data postprocessing is required to demonstrate the effects of interest with high significance, despite low efficiencies and experimental imperfections. Our approach shows that such novel detection schemes are a reliable and robust way to characterize quantum-correlated light fields for practical applications in quantum communications.
ABSTRACT
We present an efficient and robust method for the reconstruction of photon number distributions by using solely thermal noise as a probe. The method uses a minimal number of precalibrated quantum devices; only one on-off single-photon detector is sufficient. The feasibility of the method is demonstrated by the experimental inference of single-photon, thermal. and two-photon states. The method is stable to experimental imperfections and provides a direct, user-friendly quantum diagnostics tool.
ABSTRACT
We have isolated and characterized a cDNA sequence corresponding to the zebrafish muscle-specific isoform of creatine kinase. The sequence is 1552 bases in length and contains an open reading frame capable of producing a 381 amino acid protein. The sequence is very similar to muscle-specific creatine kinases isolated from other species at both the nucleotide and amino acid levels but contains some differences from a previously reported zebrafish clone.
Subject(s)
Creatine Kinase/isolation & purification , Zebrafish/metabolism , Amino Acid Sequence , Animals , Base Sequence , Creatine Kinase/metabolism , DNA, Complementary , Isoenzymes/isolation & purification , Isoenzymes/metabolism , Molecular Sequence Data , Muscles , Organ SpecificityABSTRACT
1. Gal beta 1-4GlcNAc alpha 2-6 sialyltransferase was assayed in FAZA hepatoma cells and the cell culture medium following growth of cells in presence of dexamethasone and phorbol ester. 2. There was about a seven-fold increase in sialyltransferase activities in cells and medium in presence of dexamethasone with the maximum effect occurring at 10(-6)-10(-7) M dexamethasone. 3. The presence of 10(-6) M phorbol ester in the culture medium increased sialyltransferase activities in cells and medium by ca 40% over the values found with dexamethasone alone. 4. The use of the FAZA hepatoma cell line for studies on sialyltransferase is compared with the primary hepatocyte system reported on earlier (Woloski et al., 1986).
Subject(s)
Dexamethasone/pharmacology , Liver Neoplasms, Experimental/enzymology , Sialyltransferases/metabolism , Tetradecanoylphorbol Acetate/pharmacology , Animals , Enzyme Activation/drug effects , Rats , Tumor Cells, Cultured , beta-D-Galactoside alpha 2-6-SialyltransferaseABSTRACT
PIP: Rural extension services are designed to provide rural dwellers with information needed to further technical or social development and to solve problems. Extension agents should be fully aware of their responsibility for the advice they provide. The number of rural and agricultural development and extension agencies has multiplied greatly in the past 2 decades. Agricultural extension is the principal component of most rural development strategies. Training given to men is usually economic, while that for women is devoted to household and social functioning. Programs for women usually lag general development programs. Training of women is usually not included in agricultural extension programs, especially in countries practicing segregation of the sexes. Agricultural extension programs are generally limited to cultivation techniques and neglect transformation and storage of crops and seed preparation for increased production. Measures that could improve productivity of women's agriculture-related work are expected to be delivered through the intermediacy of their husbands, but the husbands may not appreciate the import of such messages if they are not familiar with their wives' work. Agricultural training should consider all stages of production, should be delivered to the individuals actually performing the tasks, and should be ecologically appropriate. The overall objective of agricultural extension is to increase production, but most programs do not specify who is to use the surplus or to benefit from it. The rural population or the urban population may be the prime beneficiary, or cash crops may be produced for export. Although increased production should benefit the rural population through a better food supply, in reality most extension programs are devoted to cash crops for export and are less than fully successful because of problems of crop distribution and marketing and other shortcomings. Where men and women perform the same agricultural work, it should be possible for training sessions to be held jointly for both sexes, but cultural tabus and sexual division of labor may be such that different programs and personnel are required for men and women. There are currently numerous limitations on the inclusion of women in extension programs, including official policies against female employment and ignorance of the contribution of female agricultural work and social customs which discourage female social participation. There may be few or no women extension workers, female extension agents may try to avoid fieldwork, they may spend most of their time training women in household management, or their mobility may be strictly limited by family responsibilities.^ieng
Subject(s)
Agriculture , Demography , Economics , Education , Employment , Health Workforce , Human Rights , Information Services , Politics , Population , Rural Population , Social Planning , Teaching , Women's Rights , Geography , Health Planning , Organization and Administration , Population Characteristics , Socioeconomic FactorsABSTRACT
Total parenteral nutrition can maintain good nutritional status in selected patients. However, it can be accompanied by serious complications. It is generally agreed that enteral alimentation is more economical and safer. Gut should be used for nutritional replenishment whenever feasible. However, large-bore nasogastric feeding tubes can cause problems. Even fine-bore nasogastric tubes can cause aspiration pneumonia in obtunded and debilitated patients. In some patients it is clearly desirable to have the tip of the feeding tube in the distal duodenum or proximal jejunum. Previously described methods for placement of nasoenteral tubes may be unsatisfactory. We describe a safe, simple, and reliable method for endoscopic insertion of fine-bore nasoenteral feeding tube. We have used this method on 15 patients without complication.
Subject(s)
Enteral Nutrition , Fiber Optic Technology , Aged , Anorexia/therapy , Deglutition Disorders/therapy , Enteral Nutrition/methods , Humans , Male , Middle AgedABSTRACT
This study investigated the effects of local preoperative radiation on the tissue resistance to surgical infection. Preoperative radiation was given to the skin of the backs of 144 rats in two doses and wounded at intervals after the radiation. As determined by quantitative bacterial counts of the wounds 4 days after wounding, 80 to 100 percent of the rats in each group healed their wounds with counts that were 10(3) organisms per gram, or less, in spite of the dose of radiation or the interval to wounding. In an additional 560 rats, 10(4) S. aureus organisms were inoculated into the surgical wounds made at various intervals after three doses of radiation. In this part of the study, the rates of infection (as determined by bacterial counts of 10(5) per gram or more) increased significantly with the increasing dose of radiation, as well as with the increasing interval from radiation to wounding. These data demonstrate that radiated tissue cannot tolerate bacterial contamination as well as normal tissue. Since surgery in the head and neck area results in the contamination of the wounds with saliva rich in virulent organisms, we propose that preoperative radiation be discontinued in favor of postoperative radiation.