3,624 research outputs found
The Angiotensin Affair: How Great Minds Thinking Alike Came to a Historical Agreement
In 1934, J. C. Fasciolo had to submit a thesis and Dr. Houssay suggested he investigate about nephrogenic hypertension. E. BraunâMenĂ©ndez showed interest in helping and Drs. L.F. Leloir and J.M. Muñoz from the Institute of Physiology joined them in their attempt to isolate and purify the pressor substance. In 1939, they extracted the substance âhypertensionâ from the venous blood from the ischemic kidneys. They proposed an enzymeâsubstrate reaction. They named hypertensinogen the substrate and hypertensinases the enzymes that break down the hypertension. Two months following the Argentine publication, the team in the United States, formed by I.H. Page and O.M. Helmer, published their findings, which were in agreement with those reported by the Argentine team. By 1940, they isolated angiotonin, the equivalent of hypertension, and called the renin substrate hypertensinogen. In 1957, in the conference held in Ann Arbor, BraunâMenĂ©ndez and Page agreed on a new nomenclature. As a result, the words angiotensinogen and angiotensin were born from the combination of the names originally set by both teams. The discovery of the reninâangiotensin system is an example that science should follow: Value the progress made by colleagues, collaborate side by side, and pursue the ultimate truth
Linear-nonlinear duality for circuit design on quantum computing platforms
The unitary description of beam splitters (BSs) and optical parametric
amplifiers (OPAs) in terms of the dynamical Lie groups and
has a long history. Recently, an inherent duality has been proposed that
relates the unitaries of both optical devices. At the physical level, this
duality relates the linear nature of a lossless BS to the nonlinear Parametric
Down-Conversion (PDC) process exhibited by an OPA. Here, we argue that the
duality between BS and PDC can instead be naturally interpreted by analyzing
the geometrical properties of both Lie groups, an approach that explicitly
connects the dynamical group description of the optical devices with the
aforementioned duality. Furthermore, we show that the BS-PDC duality can be
represented through tensor network diagrams, enabling the implementation of a
PDC as a circuit on a standard quantum computing platform. Thus, it is feasible
to simulate nonlinear processes by using single-qubit unitaries that can be
implemented on currently available digital quantum processors
Generalized coherence vector applied to coherence transformations and quantifiers
One of the main problems in any quantum resource theory is the
characterization of the conversions between resources by means of the free
operations of the theory. In this work, we advance on this characterization
within the quantum coherence resource theory by introducing the generalized
coherence vector of an arbitrary quantum state. The generalized coherence
vector is a probability vector that can be interpreted as a concave roof
extension of the pure states coherence vector. We show that it completely
characterizes the notions of being incoherent, as well as being maximally
coherent. Moreover, using this notion and the majorization relation, we obtain
a necessary condition for the conversion of general quantum states by means of
incoherent operations. These results generalize the necessary conditions of
conversions for pure states given in the literature, and show that the tools of
the majorization lattice are useful also in the general case. Finally, we
introduce a family of coherence quantifiers by considering concave and
symmetric functions applied to the generalized coherence vector. We compare
this proposal with the convex roof measure of coherence and others quantifiers
given in the literature.Comment: 21 pages, 2 figures (close to the published version
Casimir forces from a loop integral formulation
We reformulate the Casimir force in the presence of a non-trivial background.
The force may be written in terms of loop variables, the loop being a curve
around the scattering sites. A natural path ordering of exponentials take place
when a particular representation of the scattering centres is given. The basic
object to be evaluated is a reduced (or abbreviated) classical pseudo-action
that can be operator valued.Comment: references added, text clarified in place
Silvopastoral Systems: Analyses of an Alternative to Open Swards
Silvopasture is a sustainable land use management practiced in most continents in the world including parts of southern Europe, but is not broadly used in northern and western Europe. The importance of this practice has been recognised and the last draft of the EU regulation by the European Agricultural Fund for Rural Development (http://europa.eu.int/comm/agriculture/capreform/rurdevprop_en.pdf) includes specifically funding for establishment of agroforestry practices in Europe. This paper discusses the advantages of managing semi intensive grassland within a silvopastoral system from an ecological, productive and social point of view in the south, south-central and western countries of Europe
- âŠ