Harnessing temporal modes for multi-photon quantum information processing based on integrated optics.

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'.

Local Sampling of the Wigner Function at Telecom Wavelength with Loss-Tolerant Detection of Photon Statistics.

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.

Uncovering Quantum Correlations with Time-Multiplexed Click Detection.

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.

Tomography by noise.

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.

Isolation and characterization of the muscle-specific isoform of creatine kinase from the zebrafish, Danio rerio.

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.

Stimulation of release of Gal beta 1-4GlcNAc alpha 2-6 sialyltransferase from the FAZA hepatoma cell line by dexamethasone and phorbol ester.

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).

[The role of national rural organization and agricultural extension services in relation to women]. / Le role des services nationaux d'animation rurale et de vulgarisation agricole aupres des femmes.

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

Nasoenteral feeding tube insertion via fiberoptic endoscope for enteral hyperalimentation.

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.

An experimental model to determine the effects of adjuvant therapy on the incidence of postoperative wound infection: I. Evaluating preoperative radiation therapy.

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.

How and what rural women know: experiences in Bangladesh.

PIP: A study was conducted in Bangladesh to determine the contribution rural women make to the economic conditions in their country. The study was necessary because little research has been done into the working patterns of rural women and their economic contributions have often been overlooked because they do not produce actual income. This article is a discussion of the problems faced by field researchers in countries like Bangladesh. Certain types of questions cannot be asked of women in rural Muslim areas, e.g., questions dealing with acreage of property, supply and demand in the marketplace, and irrigated land. Secluded women would have no way of knowing answers to these questions. Observation had to be used for a study of time-use, since the women do not live by the clock. Questions on women's ages can never be asked. Questions to females had to concern themselves with activities of females and questions to males, with activities of males. Rural people in Bangladesh do not seem to think in terms of exact measurement; this must be taken into account when analyzing answers. Researchers have to adapt their interviewing to the socioeconomic conditions of the area.^ieng