National University of La Plata

About: National University of La Plata is a education organization based out in La Plata, Argentina. It is known for research contribution in the topics: Population & Large Hadron Collider. The organization has 12993 authors who have published 30013 publications receiving 495118 citations. The organization is also known as: UNLP & Universidad Nacional de La Plata.

Control of a Supercapacitor Energy Storage System for Microgrid Applications

Abstract: The proper operation of a microgrid requires storage devices that increase the inertia and avoid instability of the system. This paper presents the control of an energy storage system (ESS) based on supercapacitor in the context of grid-connected microgrids. The ESS is composed of AC/DC and DC/DC converters tied by a dc link. A single sliding mode strategy is proposed to control a bidirectional dc/dc converter, capable of working properly under all operating conditions. The switching devices are commanded by a single sliding function, dynamically shaped by references sent from the microgrid central controller. This feature facilitates the implementation and design of the control law and simplifies the stability analysis over the entire operating range. The effectiveness of the proposed control strategy is illustrated by experimental results.

Stimulation of adrenal mitogenesis by N-terminal proopiocortin peptides.

Abstract: Although it was generally believed that corticotropin (ACTH) maintained both the size of the adrenal gland and its level of steroid production1, there is a growing body of evidence for a specific factor(s) distinct from ACTH which may be responsible for the stimulation of adrenocortical growth and proliferation. While direct neural influences have been proposed to be responsible for the compensatory adrenal growth following unilateral adrenalectomy2, several observations have suggested the involvement of peptides such as angiotensin3 and vasopressin4, which have other hormonal effects, or, for example, fibroblast growth factor5, which has more general mitogenic actions. Moreover ACTH inhibits cell proliferation in vitro6–8, and physiological doses in vivo cannot induce the compensatory growth and hyperplasia seen in the remaining adrenal gland after unilateral adrenalectomy9. These observations coupled with the lack of effect of chronic treatment with an ACTH antiserum on adrenal size10 and the existence of adrenal weight-maintaining activity in the plasma of patients with ACTH-secreting adenomas11, have led to the search for a pituitary factor related to ACTH which is capable of stimulating adrenal growth. We now report that peptides derived from the N-terminal non-γ-melanocyte-stimulating hormone (MSH) portion of the precursor of ACTH, proopiocortin, are potent stimulators of adrenal DNA synthesis in vitro and mitosis in vivo and may thus be involved in the physiological control of adrenal growth.

Regulatory function of delta6 desaturate -- key enzyme of polyunsaturated fatty acid synthesis.

Abstract: Polyunsaturated fatty acids are synthesized in animals by a sequence of desaturation and elongation reactions which, as we know now, follow special rules. The starting substrates are CoA thioesters of palmitoleic, oleic, linoleic and α linolenic acids. The acyl-CoA synthesis is faster than elongation or desaturation reactions (Marcel and Suzue, 1972). The enzymes involved in the elongation are found either in the endoplasmic reticulum or in mitochondria but the specificity of each group is different. The microsomal system prefers Δ6 unsaturated acyl-CoA and hexanoyl CoA whereas the mitochondrial prefers medium chain acyl-CoA (Podack et al, 1974; Hinsch and Seubert, 1975).

A preliminary study on various implementation approaches of domain-specific language

Abstract: Various implementation approaches for developing a domain-specific language are available in literature. There are certain common beliefs about the advantages/disadvantages of these approaches. However, it is hard to be objective and speak in favor of a particular one, since these implementation approaches are normally compared over diverse application domains. The purpose of this paper is to provide empirical results from ten diverse implementation approaches for domain-specific languages, but conducted using the same representative language. Comparison shows that these discussed approaches differ in terms of the effort need to implement them, however, the effort needed by a programmer to implement a domain-specific language should not be the only factor taken into consideration. Another important factor is the effort needed by an end-user to rapidly write correct programs using the produced domain-specific language. Therefore, this paper also provides empirical results on end-user productivity, which is measured as the lines of code needed to express a domain-specific program, similarity to the original notation, and how error-reporting and debugging are supported in a given implementation.

Sizing gold nanoparticles by optical extinction spectroscopy

Abstract: The measurement of optical extinction is used to determine the size of nearly spherical gold nanoparticles suspended in solution, produced by a 'reverse micelles' process. The contrast between the maximum and the minimum in the extinction spectra around 450 and 520 nm shows a linear dependence with the mean radius of the gold particles less than 3 nm; however, the method can be used to size particles up to 7 nm. Experimental results for extinction spectra can be fitted by Mie's theory if the optical constants from bulk material values are modified by introducing the limitation of the mean free path due to collisions of conduction electrons with the boundary of the nanoparticles.