Stimulated emission of polarization-entangled photons

Entangled photon pairs -- discrete light quanta that exhibit non-classical correlations -- play a crucial role in quantum information science (for example in demonstrations of quantum non-locality and quantum cryptography). At the macroscopic optical field level non-classical correlations can also be important, as in the case of squeezed light, entangled light beams and teleportation of continuous quantum variables. Here we use stimulated parametric down-conversion to study entangled states of light that bridge the gap between discrete and macroscopic optical quantum correlations. We demonstrate experimentally the onset of laser-like action for entangled photons. This entanglement structure holds great promise in quantum information science where there is a strong demand for entangled states of increasing complexity.Comment: 5 pages, 4 figures, RevTeX

Current concepts in odontohypophosphatasia form of hypophosphatasia and report of two cases

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De Broglie Wavelength of a Nonlocal Four-Photon

Superposition is one of the most distinct features of quantum theory and has been demonstrated in numerous realizations of Young's classical double-slit interference experiment and its analogues. However, quantum entanglement - a significant coherent superposition in multiparticle systems - yields phenomena that are much richer and more interesting than anything that can be seen in a one-particle system. Among them, one important type of multi-particle experiments uses path-entangled number-states, which exhibit pure higher-order interference and allow novel applications in metrology and imaging such as quantum interferometry and spectroscopy with phase sensitivity at the Heisenberg limit or quantum lithography beyond the classical diffraction limit. Up to now, in optical implementations of such schemes lower-order interference effects would always decrease the overall performance at higher particle numbers. They have thus been limited to two photons. We overcome this limitation and demonstrate a linear-optics-based four-photon interferometer. Observation of a four-particle mode-entangled state is confirmed by interference fringes with a periodicity of one quarter of the single-photon wavelength. This scheme can readily be extended to arbitrary photon numbers and thus represents an important step towards realizable applications with entanglement-enhanced performance.Comment: 19 pages, 4 figures, submitted on November 18, 200

Patient-derived iPSCs show premature neural differentiation and neuron type-specific phenotypes relevant to neurodevelopment.

Ras/MAPK pathway signaling is a major participant in neurodevelopment, and evidence suggests that BRAF, a key Ras signal mediator, influences human behavior. We studied the role of the mutation BRAFQ257R, the most common cause of cardiofaciocutaneous syndrome (CFC), in an induced pluripotent stem cell (iPSC)-derived model of human neurodevelopment. In iPSC-derived neuronal cultures from CFC subjects, we observed decreased p-AKT and p-ERK1/2 compared to controls, as well as a depleted neural progenitor pool and rapid neuronal maturation. Pharmacological PI3K/AKT pathway manipulation recapitulated cellular phenotypes in control cells and attenuated them in CFC cells. CFC cultures displayed altered cellular subtype ratios and increased intrinsic excitability. Moreover, in CFC cells, Ras/MAPK pathway activation and morphological abnormalities exhibited cell subtype-specific differences. Our results highlight the importance of exploring specific cellular subtypes and of using iPSC models to reveal relevant human-specific neurodevelopmental events

Biodegradable cationic poly(carbonates): effect of varying side chain hydrophobicity on key aspects of gene transfection

The degree of hydrophobicity in cationic polymers plays an important but often underappreciated role in the safety and efficacy of gene delivery processes. In order to further elucidate structure-activity relationships of biodegradable cationic poly(carbonate) gene carriers, we synthesized a series of narrowly dispersed homo-polymers via metal-free organocatalytic living ring-opening polymerization (ROP) of cyclic carbonate monomers bearing either alkyl (propyl, hexyl or nonyl) or 4-methyl benzyl halide side chains. The polymers were then quaternized using bis-tertiary amines to install both quaternary ammoniums and tertiary amines for DNA binding and endosomal escape, respectively. Among the polymers with similar molecular lengths and charge densities, it was found that an increase in side chain alkyl spacer length from 3 to 6 carbons significantly enhanced cellular uptake and luciferase gene expression in HepG2 and HeLa cell lines without causing overt hemolysis and cytotoxicity. A further increase of side chain alkyl length to 9 carbons, however, led to a drastic decline in gene expression due to increased cellular toxicity, which was correlated with an increased disruption and lysis of red blood cell membranes. Interestingly, the incorporation of an aromatic 4-methyl benzyl spacer increased DNA binding strength, reduced particle sizes of resultant DNA complexes, and enhanced cellular uptake, leading to improved luciferase gene expression, albeit with higher levels of hemolysis and cytotoxicity. Taken together, the findings of this study demonstrate that a delicate balance between cationic charge density and hydrophobicity could be achieved by utilizing a hexyl spacer in the side chains of cationic poly(carbonates), hence providing insights on the future development of non-viral cationic polymeric gene delivery systems. Statement of Significance: Owing to their ease of synthesis and well-controlled polymerization, biodegradable cationic poly(carbonates) have emerged as a highly promising class of biomaterials for gene delivery. The hydrophobicity of side chains in cationic polymers plays an important but often underappreciated role in influencing key aspects of gene transfection. In our efforts to improve gene transfection and understand structure-activity relationships, we synthesized a series of cationic polymers bearing a common poly(carbonate) backbone, and with side chains containing various hydrophobic spacers (propyl, hexyl, 4-methyl benzyl or nonyl) before the cationic moiety. A moderate degree of hydrophobicity was optimal as the cationic poly(carbonate) with hexyl side chains mediated high gene transfection efficiencies while causing low cytotoxicities. (111 words

Comparative study of intestine length, weight and digestibility on different body weight chickens

This experiment was conducted to compare the difference of digestibility on different body weight chickens. Twenty-seven (27) 58-week-old New Yangzhou Chickens of three grade sizes (small 2.0 kg, medium 2.5 kg, and large 3.0 kg) were selected and distributed into three groups (Groups 1 to 3) of nine birds/group, and each group was represented by three replicates. Nutrient retention ratio was determined by adopting whole gather excretion method. In the end of metabolism experiment, all the birds were killed, and the intestine length and intestine weight were measured. Results show that, the amount of feed intake and excretion increased along with body weight gain; the feed intake and excretion in group 3 were significantly higher than that in group 1 (P < 0.05). The sidelong lengths in the three groups were evidently different. Although, the intestinal length as well as the length of the jejunum, ileum and rectum appeared to be gradually improved with the body weight increase, there were no significant differences among the three groups (P > 0.05). The weightier the intestines, the more was body weight of the birds. The retention ratio of energy, crude fiber and neutral detergent fiber increased with body weight gain, but the differences were not significant (P > 0.05). It was concluded that there was no correlation between body weight and digestibility.Keywords: Digestibility, body weight, cock.African Journal of Biotechnology Vol. 12(32), pp. 5097-510

Feed rate modeling in circular–circular interpolation discontinuity for high-speed milling

In this paper, a modeling approach is presented in order to evaluate feed rate during a circular interpolation in high-speed milling. The developed model depends on the type of discontinuity and the kinematic performance of the machine tool. To begin with, a feed rate modeling for circular interpolation with continuity in tangency is developed. After, the discontinuity in tangency between two circular interpolations is replaced by discontinuity in curvature by adding a fillet which is in relation to the functional tolerance ε imposed in the part design. An experimental study has been carried out to validate the models

浅析公路景观设计与评价

Author name used in this publication: SHI Wen-zhongAuthor name used in this publication: 贺志勇Author name used in this publication: 张肖宁2002-2003 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Super-resolving phase measurements with a multi-photon entangled state

Using a linear optical elements and post-selection, we construct an entangled polarization state of three photons in the same spatial mode. This state is analogous to a ``photon-number path entangled state'' and can be used for super-resolving interferometry. Measuring a birefringent phase shift, we demonstrate two- and three-fold improvements in phase resolution.Comment: 4 pages, 3 figure

Antioxidant treatment enhances human mesenchymal stem cell anti-stress ability and therapeutic efficacy in an acute liver failure model

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