1,760 research outputs found
Typing Quantum Superpositions and Measurement
We propose a way to unify two approaches of non-cloning in quantum lambda-calculi. The first approach is to forbid duplicating variables, while the second is to consider all lambda-terms as algebraic-linear functions. We illustrate this idea by defining a quantum extension of first-order simply-typed lambda-calculus, where the type is linear on superposition, while allows cloning base vectors. In addition, we provide an interpretation of the calculus where superposed types are interpreted as vector spaces and non-superposed types as their basis.Fil: DÃaz Caro, Alejandro. Universidad Nacional de Quilmes. Departamento de Ciencia y TecnologÃa; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas; ArgentinaFil: Dowek, Gilles. Institut National de Recherche en Informatique et en Automatique; Franci
Are the basal cells of the mammalian epididymis still an enigma?
Basal cells are present in the columnar pseudostratified epithelium covering the epididymis of all mammalian species, which regulates the microenvironment where the functionally incompetent germ cells produced by the testis are matured and stored. Striking novelties have come from investigations on epididymal basal cells in the past 30\u201340 years. In addition to an earlier hypothesised scavenger role for basal cells, linked to their proven extratubular origin and the expression of macrophage antigens, basal cells have been shown to be involved in cell\u2013cell cross-talk, as well as functioning as luminal sensors to regulate the activity of principal and clear cells. Involvement of basal cells in the regulation of electrolyte and water transport by principal cells was hypothesised. This control is suggested to be mediated by the local formation of prostaglandins. Members of the aquaporin (AQP) and/or aquaglyceroporin family (AQP3, AQP7 and AQP8) are also specifically expressed in the rat epididymal basal cells. Transport of glycerol and glycerylphosphorylcholine from the epithelium of the epididymis to the lumen in relation to sperm maturation may be mediated by AQP. Most probably basal cells collaborate to the building up of the blood\u2013epididymis barrier through cell adhesion molecules, implying an involvement in immune control exerted towards sperm cells, which are foreigners in the environment in which they were produced
Immunolocalization of Aquaporin Water Channels in the Domestic Cat Male Genital Tract
Four different aquaporins (AQP1, 2, 5 and 9), integral
membrane water channels that facilitate rapid passive movement
of water, were immuno-localized in the excurrent ducts
collected from sexually mature cats during orchiectomy.
Aquaporins 1, 2 and 9, were immuno-localized at distinct
levels, whereas AQP5 was undetectable all along the feline
genital tract. No immunoreactivity was present at the level of
the rete testis with any of the antibodies tested. In the efferent
ducts, AQP1-immunoreactivity was strongly evidenced at the
apical surface of the non-ciliated cells, and AQP9-immunoreactivity
was shown at the periphery of both ciliated and nonciliated
cells. Aquaporins 2 was absent in the caput epididymidis,
either in the efferent ducts or in the epididymal duct.
Otherwise, AQP2 was increasingly localized at the adluminal
surface of principal cells from the corpus to the cauda
epididymidis and more weakly in the vas deferens epithelium.
The supranuclear zone of the epididymal principal cells was
AQP9-immunoreactive throughout the duct, with the exclusion
of the vacuolated sub-region of the caput and with higher
reaction intensity in the cauda region. AQP1 was present in the
blood vessels all along the genital tract. AQP1 was expressed
also in the smooth muscle layer of the vas deferens. The tested
AQP molecules showed a different expression pattern in
comparison with laboratory mammals, primates and the dog,
unique other carnivore species studied to date. The present
information is possibly useful in regard to the regional
morphology of the feline epididymis and correlated functions,
which are still a matter of debate
Semantics of a Typed Algebraic Lambda-Calculus
Algebraic lambda-calculi have been studied in various ways, but their
semantics remain mostly untouched. In this paper we propose a semantic analysis
of a general simply-typed lambda-calculus endowed with a structure of vector
space. We sketch the relation with two established vectorial lambda-calculi.
Then we study the problems arising from the addition of a fixed point
combinator and how to modify the equational theory to solve them. We sketch an
algebraic vectorial PCF and its possible denotational interpretations
Bringing the Future Within Reach: Celebrating 75 Years of the NASA John H. Glenn Research Center
The National Aeronautics and Space Administration (NASA) Glenn Research Center in Cleveland, Ohio, has been making the future for 75 years. The center's work with aircraft engines, high-energy fuels, communications technology, electric propulsion, energy conversion and storage, and materials and structures has been, and continues to be, crucial to both the Agency and the region. Glenn has partnered with industry, universities, and other agencies to continually advance technologies that are propelling the nation's aerospace community into the future. Nonetheless these continued accomplishments would not be possible without the legacy of our first three decades of research, which led to over one hundred R&D 100 Awards, three Robert J. Collier Trophies, and an Emmy. Glenn, which is located in Cleveland, Ohio, is 1 of 10 NASA field centers, and 1 of only 3 that stem from an earlier research organization-the National Advisory Committee for Aeronautics (NACA). Glenn began operation in 1942 as the NACA Aircraft Engine Research Laboratory (AERL). In 1947 the NACA renamed the lab the Flight Propulsion Laboratory to reflect the expansion of the research. In September 1948, following the death of the NACA's Director of Aeronautics, George Lewis, the NACA rededicated the lab as the Lewis Flight Propulsion Laboratory. On 1 October 1958, the lab was incorporated into the new NASA space agency and was renamed the NASA Lewis Research Center. Following John Glenn's return to space on the space shuttle, on 1 March 1999 the center name was changed once again, becoming the NASA John H. Glenn Research Center
Environmental impacts and risk assessment in the re-use of Cr-bearing pyrolyzed tannery wastes: A case study in a residential area
Increasing concern has been raised on the environmental impacts of chromium -tanning wastes recycling. In particular, the pyrolytic conversion of leather industry sludges into Cr(VI)-free carbonized residues is believed to represent a viable route for a sustainable re -use of this type of wastes. The aim of this study was to determine the impact of recycled Cr-bearing pyrolyzed char (named KEU) as backfilling material for road construction in an urban area in Tuscany (Italy). Geochemical and chromium -isotope data, together with microstructural analyses (HR-TEM and XAS), indicate that the presence of KEU results in a significant enhancement of the natural Cr background. The results support the hypothesis that, in environmental conditions, the Cr (III) hosted in KEU is converted into Cr(VI), which is leached out by rainwater. Indeed, Cr(VI) is dispersed in surface water, reaching concentrations up to 18 mg/L and it also occurs in coatings on the surface gravel of unpaved roads. The 53 Cr/ 52 Cr ratio measured in KEU, reported in delta 53 Cr notation, was in the restricted range delta 53 Cr = - 0.031 +/- 0.057 %o ; on the contrary, the delta 53 Cr in water varied between + 1.581 +/- 0.038 %o and + 3.261 +/- 0.191 %o , indicating the reduction of Cr(VI) after the pristine oxidative mobilization. The risk -based soil screening levels (SSLs) for total Cr are well above the concentration measured in soil for all the exposure pathways. On the contrary, the SSL for Cr(VI)indicates that soil contamination poses health hazards for residents
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