Álvaro Correa - Academia.edu (original) (raw)

Papers by Álvaro Correa

Research paper thumbnail of Breakdown of the Fermi-liquid regime in the 2D Hubbard model from a two-loop field-theoretical renormalization group approach

Physical Review B, 2007

We analyze the particle-hole symmetric two-dimensional Hubbard model on a square lattice starting... more We analyze the particle-hole symmetric two-dimensional Hubbard model on a square lattice starting from weak-to-moderate couplings by means of the field-theoretical renormalization group (RG) approach up to two-loop order. This method is essential in order to evaluate the effect of the momentum-resolved anomalous dimension eta(textbfp)\eta(\textbf{p})eta(textbfp) which arises in the normal phase of this model on the corresponding low-energy single-particle excitations. As a result, we find important indications pointing to the existence of a non-Fermi liquid (NFL) regime at temperature Tto0T\to 0Tto0 displaying a truncated Fermi surface (FS) for a doping range exactly in between the well-known antiferromagnetic insulating and the dx2−y2d_{x^2-y^2}dx2−y2-wave singlet superconducting phases. This NFL evolves as a function of doping into a correlated metal with a large FS before the dx2−y2d_{x^2-y^2}dx2−y2-wave pairing susceptibility finally produces the dominant instability in the low-energy limit.

Research paper thumbnail of Electrophysiological Studies and Identification of Possible Sex Pheromone Components of Brazilian Populations of the Sugarcane Borer, Diatraea saccharalis

Diatraea saccharalis, Sex Pheromone, (9Z,11E)-Hexadecadienal Virgin female gland extracts of suga... more Diatraea saccharalis, Sex Pheromone, (9Z,11E)-Hexadecadienal Virgin female gland extracts of sugarcane moth Diatraea saccharalis (Fabricius) (Lepidoptera: Pyralidae), from three locations in Brazil, have been analyzed. By GC-MS analysis and comparison of the chromatographic retention time of the components of the pheromone gland with those retention times of synthetic standards, we observed the presence of (Z)hexadec-11-enal (1), hexadecanal (2), (9E,11Z)-hexadecadienal (4), (9Z,11Z)-hexadecadienal and (9E,11E)-hexadecadienal , as minor components besides the major constituent (9Z,11E)-hexadecadienal (3) already reported. We found no variations in the composition of the gland extracts deriving from the three Brazilian populations and only two compounds, (Z)-hexadec-11-enal (1) and (9Z,11E)-hexadecadienal , elicited antennal responses (GC-EAD). In electroantennography (EAG), however, pure compounds 1 and 3, a binary mixture containing 1 and 3, and a mixture containing all of the six synthetic compounds 1Ð6 elicited a depolarization in male antennae of D. saccharalis, without any statistically different delay. The EAG responses to the other isomers of 9,11-hexadecadienal were small and not significantly different from the control, except for the (9Z,11Z)-isomer (5) which showed an relatively strong electroantennal activity.

Research paper thumbnail of Two-loop renormalization group calculation of response functions for a two-dimensional flat Fermi surface

Research paper thumbnail of PCR-RFLP to identify Leishmania ( Viannia) braziliensis and L. ( Leishmania) amazonensis causing American cutaneous leishmaniasis

Acta Tropica, 2004

A PCR-RFLP based method was developed to diagnose and identify the Leishmania species causing Ame... more A PCR-RFLP based method was developed to diagnose and identify the Leishmania species causing American cutaneous leishmaniasis (ACL) in a panel of clinical samples obtained from an endemic region of Brazil. The comparison of the results obtained by PCR-RFLP and PCR-hybridization in the identification of Leishmania (Viannia) braziliensis and L. (Leishmania) amazonensis were highly concordant (κ=91.5%). The PCR-RFLP method was reliable, fast and easy to conduct on biopsies and presents potential value of utmost importance for the diagnosis and identification of Leishmania in clinical specimens, infected reservoirs and vectors.

Research paper thumbnail of Caracterização dos hemócitos de operários de Nasutitermes coxipoensis(Holmgren) (Isoptera: Termitidae) e avaliação hemocitária após parasitismo por Metarhizium anisopliae

Neotropical Entomology, 2009

We aimed to characterize the morphology and ultrastructure of hemocytes of Nasutitermes coxipoens... more We aimed to characterize the morphology and ultrastructure of hemocytes of Nasutitermes coxipoensis (Holmgren) workers and to quantify the cell types 24h, 48h and 72h after inoculation with Metarhizium anisopliae. Six hemocytes types were identified, plasmatocyte, granulocyte, spherulocyte, prohemocyte, adipohemocyte and eonocytoid Hemocytes did not present any morphological alteration at the several observation periods, but they did have a change in their abundance, as observed for spherulocytes, adipohemocytes and eonocytoids at all intervals, and for plasmatocytes and granulocytes at 48h after host inoculation. We argue on the possible reasons and implications of the observed changes.

Research paper thumbnail of Anti-Trypanosoma cruzi Immunoglobulin G1 Can Be a Useful Tool for Diagnosis and Prognosis of Human Chagas' Disease

Clinical and Vaccine Immunology, 2001

Two functionally distinct antibodies, categorized as conventional serology antibodies (CSA) and l... more Two functionally distinct antibodies, categorized as conventional serology antibodies (CSA) and lytic antibodies (LA) have been described in Chagas' disease, based on their ability to bind to fixed epimastigotes (EPI) or live trypomastigotes (TRYPO), respectively. In this study, the profile of immunoglobulin G (IgG) subclasses of CSA and LA were analyzed by flow cytometry using serum samples from chronic chagasic patients with the indeterminate (IND), cardiac (CARD), and digestive (DIG) clinical forms of the disease. The results were expressed as percentage of positive fluorescent parasites (PPFP) for each sample. CSA showed a higher PPFP than LA for all samples. At serum dilutions between 1:256 and 1:2,048, IgG1 anti-EPI was able to distinguish chagasic from nonchagasic individuals. Different profiles of IgG subclasses were observed for CSA and LA. IgG1 and IgG2 were the main subclasses in CSA, whereas IgG1 and IgG3 were the predominant ones in LA. The reactivity of IgG2 anti-EPI was greater in IND and CARD than in DIG patients. Furthermore, a low level of IgG1 and IgG3 LA was associated with most of the CARD patients. On the other hand, a high level of IgG1 LA was associated with most of the IND patients. In summary, our findings indicate the potential of IgG1 anti-EPI for serological diagnosis of Chagas' disease, providing further evidence for a protective role of LA, and show that IgG1 anti-live Trypanosoma cruzi TRYPO may be used to predict the risk of cardiac damage in Chagas' disease.

Research paper thumbnail of Microsatellite-enriched genomic libraries as a source of polymorphic loci for Schistosoma mansoni

Schistosoma mansoni were developed using four genomic microsatellite-enriched libraries. Microsat... more Schistosoma mansoni were developed using four genomic microsatellite-enriched libraries. Microsatellites were observed in 65.4% of all sequences. Primer pairs were designed and tested for 23 loci. Eighteen loci produced amplification products, out of which 11 were polymorphic and were further characterized on 100 individuals of S. mansoni. Two to 19 alleles per locus were detected. The average values of expected and observed heterozygosities among the 11 loci were 0.79 and 0.59, respectively.

Research paper thumbnail of Breakdown of the Fermi-liquid regime in the 2D Hubbard model from a two-loop field-theoretical renormalization group approach

Physical Review B, 2007

We analyze the particle-hole symmetric two-dimensional Hubbard model on a square lattice starting... more We analyze the particle-hole symmetric two-dimensional Hubbard model on a square lattice starting from weak-to-moderate couplings by means of the field-theoretical renormalization group (RG) approach up to two-loop order. This method is essential in order to evaluate the effect of the momentum-resolved anomalous dimension eta(textbfp)\eta(\textbf{p})eta(textbfp) which arises in the normal phase of this model on the corresponding low-energy single-particle excitations. As a result, we find important indications pointing to the existence of a non-Fermi liquid (NFL) regime at temperature Tto0T\to 0Tto0 displaying a truncated Fermi surface (FS) for a doping range exactly in between the well-known antiferromagnetic insulating and the dx2−y2d_{x^2-y^2}dx2−y2-wave singlet superconducting phases. This NFL evolves as a function of doping into a correlated metal with a large FS before the dx2−y2d_{x^2-y^2}dx2−y2-wave pairing susceptibility finally produces the dominant instability in the low-energy limit.

Research paper thumbnail of Electrophysiological Studies and Identification of Possible Sex Pheromone Components of Brazilian Populations of the Sugarcane Borer, Diatraea saccharalis

Diatraea saccharalis, Sex Pheromone, (9Z,11E)-Hexadecadienal Virgin female gland extracts of suga... more Diatraea saccharalis, Sex Pheromone, (9Z,11E)-Hexadecadienal Virgin female gland extracts of sugarcane moth Diatraea saccharalis (Fabricius) (Lepidoptera: Pyralidae), from three locations in Brazil, have been analyzed. By GC-MS analysis and comparison of the chromatographic retention time of the components of the pheromone gland with those retention times of synthetic standards, we observed the presence of (Z)hexadec-11-enal (1), hexadecanal (2), (9E,11Z)-hexadecadienal (4), (9Z,11Z)-hexadecadienal and (9E,11E)-hexadecadienal , as minor components besides the major constituent (9Z,11E)-hexadecadienal (3) already reported. We found no variations in the composition of the gland extracts deriving from the three Brazilian populations and only two compounds, (Z)-hexadec-11-enal (1) and (9Z,11E)-hexadecadienal , elicited antennal responses (GC-EAD). In electroantennography (EAG), however, pure compounds 1 and 3, a binary mixture containing 1 and 3, and a mixture containing all of the six synthetic compounds 1Ð6 elicited a depolarization in male antennae of D. saccharalis, without any statistically different delay. The EAG responses to the other isomers of 9,11-hexadecadienal were small and not significantly different from the control, except for the (9Z,11Z)-isomer (5) which showed an relatively strong electroantennal activity.

Research paper thumbnail of Two-loop renormalization group calculation of response functions for a two-dimensional flat Fermi surface

Research paper thumbnail of PCR-RFLP to identify Leishmania ( Viannia) braziliensis and L. ( Leishmania) amazonensis causing American cutaneous leishmaniasis

Acta Tropica, 2004

A PCR-RFLP based method was developed to diagnose and identify the Leishmania species causing Ame... more A PCR-RFLP based method was developed to diagnose and identify the Leishmania species causing American cutaneous leishmaniasis (ACL) in a panel of clinical samples obtained from an endemic region of Brazil. The comparison of the results obtained by PCR-RFLP and PCR-hybridization in the identification of Leishmania (Viannia) braziliensis and L. (Leishmania) amazonensis were highly concordant (κ=91.5%). The PCR-RFLP method was reliable, fast and easy to conduct on biopsies and presents potential value of utmost importance for the diagnosis and identification of Leishmania in clinical specimens, infected reservoirs and vectors.

Research paper thumbnail of Caracterização dos hemócitos de operários de Nasutitermes coxipoensis(Holmgren) (Isoptera: Termitidae) e avaliação hemocitária após parasitismo por Metarhizium anisopliae

Neotropical Entomology, 2009

We aimed to characterize the morphology and ultrastructure of hemocytes of Nasutitermes coxipoens... more We aimed to characterize the morphology and ultrastructure of hemocytes of Nasutitermes coxipoensis (Holmgren) workers and to quantify the cell types 24h, 48h and 72h after inoculation with Metarhizium anisopliae. Six hemocytes types were identified, plasmatocyte, granulocyte, spherulocyte, prohemocyte, adipohemocyte and eonocytoid Hemocytes did not present any morphological alteration at the several observation periods, but they did have a change in their abundance, as observed for spherulocytes, adipohemocytes and eonocytoids at all intervals, and for plasmatocytes and granulocytes at 48h after host inoculation. We argue on the possible reasons and implications of the observed changes.

Research paper thumbnail of Anti-Trypanosoma cruzi Immunoglobulin G1 Can Be a Useful Tool for Diagnosis and Prognosis of Human Chagas' Disease

Clinical and Vaccine Immunology, 2001

Two functionally distinct antibodies, categorized as conventional serology antibodies (CSA) and l... more Two functionally distinct antibodies, categorized as conventional serology antibodies (CSA) and lytic antibodies (LA) have been described in Chagas' disease, based on their ability to bind to fixed epimastigotes (EPI) or live trypomastigotes (TRYPO), respectively. In this study, the profile of immunoglobulin G (IgG) subclasses of CSA and LA were analyzed by flow cytometry using serum samples from chronic chagasic patients with the indeterminate (IND), cardiac (CARD), and digestive (DIG) clinical forms of the disease. The results were expressed as percentage of positive fluorescent parasites (PPFP) for each sample. CSA showed a higher PPFP than LA for all samples. At serum dilutions between 1:256 and 1:2,048, IgG1 anti-EPI was able to distinguish chagasic from nonchagasic individuals. Different profiles of IgG subclasses were observed for CSA and LA. IgG1 and IgG2 were the main subclasses in CSA, whereas IgG1 and IgG3 were the predominant ones in LA. The reactivity of IgG2 anti-EPI was greater in IND and CARD than in DIG patients. Furthermore, a low level of IgG1 and IgG3 LA was associated with most of the CARD patients. On the other hand, a high level of IgG1 LA was associated with most of the IND patients. In summary, our findings indicate the potential of IgG1 anti-EPI for serological diagnosis of Chagas' disease, providing further evidence for a protective role of LA, and show that IgG1 anti-live Trypanosoma cruzi TRYPO may be used to predict the risk of cardiac damage in Chagas' disease.

Research paper thumbnail of Microsatellite-enriched genomic libraries as a source of polymorphic loci for Schistosoma mansoni

Schistosoma mansoni were developed using four genomic microsatellite-enriched libraries. Microsat... more Schistosoma mansoni were developed using four genomic microsatellite-enriched libraries. Microsatellites were observed in 65.4% of all sequences. Primer pairs were designed and tested for 23 loci. Eighteen loci produced amplification products, out of which 11 were polymorphic and were further characterized on 100 individuals of S. mansoni. Two to 19 alleles per locus were detected. The average values of expected and observed heterozygosities among the 11 loci were 0.79 and 0.59, respectively.