187 research outputs found
Benchmarking the Variational Reduced Density Matrix Theory in the Doubly Occupied Configuration Interaction Space with Integrable Pairing Models
The variational reduced density matrix theory has been recently applied with great success to models within the truncated doubly occupied configuration interaction space, which corresponds to the seniority zero subspace. Conservation of the seniority quantum number restricts the Hamiltonians to be based on the SU(2) algebra. Among them there is a whole family of exactly solvable Richardson-Gaudin pairing Hamiltonians. We benchmark the variational theory against two different exactly solvable models, the Richardson-Gaudin-Kitaev and the reduced BCS Hamiltonians. We obtain exact numerical results for the so-called PQGT N-representability conditions in both cases for systems that go from 10 to 100 particles. However, when random single-particle energies as appropriate for small superconducting grains are considered, the exactness is lost but still a high accuracy is obtained.Fil: Rubio GarcÃa, A.. Instituto de Estructura de la Materia; España. Consejo Superior de Investigaciones CientÃficas; EspañaFil: Alcoba, Diego Ricardo. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de FÃsica de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de FÃsica de Buenos Aires; ArgentinaFil: Capuzzi, Pablo. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de FÃsica de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de FÃsica de Buenos Aires; ArgentinaFil: Dukelsky, J.. Consejo Superior de Investigaciones CientÃficas; España. Instituto de Estructura de la Materia; Españ
Do children with uncomplicated severe acute malnutrition need antibiotics? A systematic review and meta-analysis.
Current (1999) World Health Organization guidelines recommend giving routine antibiotics (AB) for all children with severe acute malnutrition (SAM), even if they have uncomplicated disease with no clinically obvious infections. We examined the evidence behind this recommendation
A model for optimal fleet composition of vessels for offshore wind farm maintenance
We present a discrete optimisation model that chooses an optimal fleet of vessels to support maintenance operations at Offshore Wind Farms (OFWs). The model is presented as a bi-level problem. On the first (tactical) level, decisions are made on the fleet composition for a certain time horizon. On the second (operational) level, the fleet is used to optimise the schedule of operations needed at the OWF, given events of failures and weather conditions
Determination of exchange coupling constants in linear polyradicals by means of local spins
This work extends the previously reported studies (Oliva et al. in Theor Chem Acc 132:1329, 2013, Theor Chem Acc 134:9, 2015) on electronic structures of simple polyhedral polyradicals constructed from s = ½ closo-carborane CB11H12 • structural units. Linear polyradical structures obtained from these units connected by means of –CH2– bridges are described in terms of their energies and local spins. The resulting spin states of these chains have been mapped onto a phenomenological Heisenberg spin Hamiltonian, providing the evaluation of spin exchange coupling constants and performing an analysis of their transferability. The eigenvalues of this Hamiltonian allow one to determine the ground spin state and the suitable combinations of spin orientations of the magnetic sites. We prove that the minimal energy in all these systems corresponds to the highest-spin state.Instituto de Investigaciones FisicoquÃmicas Teóricas y Aplicada
Determination of exchange coupling constants in linear polyradicals by means of local spins
This work extends the previously reported studies (Oliva et al. in Theor Chem Acc 132:1329, 2013, Theor Chem Acc 134:9, 2015) on electronic structures of simple polyhedral polyradicals constructed from s = ½ closo-carborane CB11H12 • structural units. Linear polyradical structures obtained from these units connected by means of –CH2– bridges are described in terms of their energies and local spins. The resulting spin states of these chains have been mapped onto a phenomenological Heisenberg spin Hamiltonian, providing the evaluation of spin exchange coupling constants and performing an analysis of their transferability. The eigenvalues of this Hamiltonian allow one to determine the ground spin state and the suitable combinations of spin orientations of the magnetic sites. We prove that the minimal energy in all these systems corresponds to the highest-spin state.Instituto de Investigaciones FisicoquÃmicas Teóricas y Aplicada
Molecular diagnosis and typing of Trypanosoma cruzi populations and lineages in cerebral Chagas disease in a patient with AIDS
Trypanosoma cruzi DNA was amplified from an intracranial biopsy and peripheral blood of an HIV patient with encephalitis; this episode was indicative of AIDS and congenital Chagas disease. The analysis of a microsatellite locus revealed a multiclonal parasite population at the brain lesion with a more complex minicircle signature than that profiled in blood using restriction fragment length polymorphism (RFLP)-PCR and low stringency single primer (LSSP) PCR. Interestingly, different sublineages of T. cruzi II were detected in blood and brain by means of spliced-leader and 24s ribosomal-DNA amplifications. Quantitative-competitive PCR monitored the decrease of parasitic load during treatment and secondary prophylaxis with benznidazole. The synergy between parasiticidal plus antiretroviral treatments probably allowed the patient a longer survival than usually achieved in similar episodes. This is the first case report demonstrating a differential distribution of natural parasite populations and sublineages in Chagas disease reactivation, showing the proliferation of cerebral variants not detectable in peripheral blood.Fil: Burgos, Juan Miguel. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Instituto de Investigaciones en IngenierÃa Genética y BiologÃa Molecular "Dr. Héctor N. Torres"; ArgentinaFil: Bergher, Sandra B.. Gobierno de la Ciudad de Buenos Aires. Hospital "Ignacio Pirovano"; ArgentinaFil: Freitas, Jorge M.. Universidade Federal de Minas Gerais; BrasilFil: Bisio, Margarita MarÃa Catalina. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Instituto de Investigaciones en IngenierÃa Genética y BiologÃa Molecular "Dr. Héctor N. Torres"; ArgentinaFil: Altcheh, Jaime Marcelo. Consejo Nacional de Investigaciones CientÃficas y Técnicas; Argentina. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez"; ArgentinaFil: Teijeiro, Ricardo. Gobierno de la Ciudad de Buenos Aires. Hospital "Ignacio Pirovano"; ArgentinaFil: Begher, Sandra B.. Gobierno de la Ciudad de Buenos Aires. Hospital "Ignacio Pirovano"; ArgentinaFil: Freilij, Hector León. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez"; ArgentinaFil: Deccarlini, Florencia. Gobierno de la Ciudad de Buenos Aires. Hospital "Ignacio Pirovano"; ArgentinaFil: Levalle, Jorge. Gobierno de la Ciudad de Buenos Aires. Hospital "Ignacio Pirovano"; ArgentinaFil: Lopez Alcoba, Horacio. Gobierno de la Ciudad de Buenos Aires. Hospital "Ignacio Pirovano"; ArgentinaFil: Burgos, Juan Miguel. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Instituto de Investigaciones en IngenierÃa Genética y BiologÃa Molecular "Dr. Héctor N. Torres"; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de FisiologÃa, BiologÃa Molecular y Celular; ArgentinaFil: Levin, Mariano Jorge. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Instituto de Investigaciones en IngenierÃa Genética y BiologÃa Molecular "Dr. Héctor N. Torres"; ArgentinaFil: Duffy, Tomás. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Instituto de Investigaciones en IngenierÃa Genética y BiologÃa Molecular "Dr. Héctor N. Torres"; ArgentinaFil: Macedo, Andrea M.. Universidade Federal de Minas Gerais; BrasilFil: Schijman, Alejandro Gabriel. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Instituto de Investigaciones en IngenierÃa Genética y BiologÃa Molecular "Dr. Héctor N. Torres"; Argentin
Performance of Shannon-entropy compacted N-electron wave functions for configuration interaction methods
The coefficients of full configuration interaction wave functions (FCI) for N-electron systems expanded in N-electron Slater determinants depend on the orthonormal one-particle basis chosen although the total energy remains invariant. Some bases result in more compact wave functions, i.e. result in fewer determinants with significant expansion coefficients. In this work, the Shannon entropy, as a measure of information content, is evaluated for such wave functions to examine whether there is a relationship between the FCI Shannon entropy of a given basis and the performance of that basis in truncated CI approaches. The results obtained for a set of randomly picked bases are compared to those obtained using the traditional canonical molecular orbitals, natural orbitals, seniority minimising orbitals and a basis that derives from direct minimisation of the Shannon entropy. FCI calculations for selected atomic and molecular systems clearly reflect the influence of the chosen basis. However, it is found that there is no direct relationship between the entropy computed for each basis and truncated CI energies.Fil: Alcoba, Diego Ricardo. Consejo Nacional de Investigaciones CientÃficas y Técnicas; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas; ArgentinaFil: Torre, Alicia. Universidad de Buenos Aires; Argentina. Universidad de Buenos Aires; ArgentinaFil: Lain, Luis. Universidad del PaÃs Vasco; España. Universidad del PaÃs Vasco; EspañaFil: Massaccesi, Gustavo Ernesto. Universidad del PaÃs Vasco; España. Universidad del PaÃs Vasco; EspañaFil: Oña, Ofelia Beatriz. Universidad de Buenos Aires; Argentina. Universidad de Buenos Aires; ArgentinaFil: Ayers, P. W.. Consejo Nacional de Investigaciones CientÃficas y Técnicas; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas; ArgentinaFil: Van Raemdonck, M.. Mcmaster University; Canadá. Mcmaster University; CanadáFil: Bultinck, P.. University of Ghent; Bélgica. University of Ghent; BélgicaFil: Van Neck, D.. University of Ghent; Bélgica. University of Ghent; Bélgic
Proadrenomedullin and copeptin in pediatric pneumonia: a prospective diagnostic accuracy study
Developmental potential of in vitro or in vivo matured oocytes
Summary This study compared the embryological features of mature and immature oocytes (different stages) collected from stimulated cycles of in vitro fertilization (IVF). Immature oocytes were identified, classified as PI (prophase I -germinal vesicle, GV) or MI (metaphase I), were matured in vitro and fertilized using the intra-cytoplasmic sperm injection (ICSI) technique. Fertilization potential, cleavage, and subsequent transfer/cryopreservation of the embryos derived from these in vitro matured oocytes were compared with those of in vivo matured oocytes (collected at the MII stage). The characteristics of embryos derived from gametes recovered in the MI and MII stages were similar. The fertilization rate of immature oocytes recovered in PI was significantly lower than that of MII oocytes (P = 0.031), and the cleavage rate of the PI group was also lower than that of the MI (P = 0.004) and MII (P < 0.001) groups. In vitro maturation of MI oocytes is a suitable alternative when immature oocytes are recovered, as their characteristics and development are similar to those of in vivo matured oocytes. Optimization of outcomes for PI oocytes will require development of techniques that can distinguish which of these gametes will mature and fertilize
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