Papers by Ana Cristina Ferreira
International Journal of Geometric Methods in Modern Physics, 2014
In this note we study a correspondence between the space of three-forms on a four-manifold and th... more In this note we study a correspondence between the space of three-forms on a four-manifold and the space of three-forms on the moduli space of instantons. We then specialize to the case where the base manifold is the four-sphere.
Proceedings of the Edinburgh Mathematical Society, 2013
We prove a vanishing theorem for the twisted de Rham cohomology of a compact manifold.
The Quarterly Journal of Mathematics, 2013
We develop a notion of Einstein manifolds with skew torsion on compact, orientable Riemannian man... more We develop a notion of Einstein manifolds with skew torsion on compact, orientable Riemannian manifolds of dimension four. We prove an analogue of the Hitchin-Thorpe inequality and study the case of equality. We use the link with selfduality to study the moduli space of 1-instantons on S 4 for a family of metrics defined by Bonneau.
CIDADES Comunidades e Territórios, 2014
Revista Portuguesa de Cardiologia (English Edition), 2013
Revista Portuguesa de Cardiologia, 2013
CIDADES, Comunidades e Territórios, 2005
Bolema: Boletim de Educação Matemática, 2013
CIDADES, Comunidades e Territórios, 2004
Case Reports in Radiology, 2014
The authors present a case of a presacral myelolipoma diagnosed in an 84-year-old male patient wi... more The authors present a case of a presacral myelolipoma diagnosed in an 84-year-old male patient with longstanding pelvic pain and past medical history of bladder cancer. Pelvic computed tomography (CT) revealed a well-encapsulated and lobulated presacral mass, with mixed fat and soft-tissue attenuation. Magnetic resonance (MR) imaging provided further confirmation of macroscopic intralesional fat and excluded either adjacent bone invasion or bladder cancer recurrence. A presacral myelolipoma was suspected based on imaging findings, with liposarcoma and teratoma having also been considered for the differential diagnosis. The histological confirmation of the tumor was only attained postoperatively. This case report alerts to the possible presacral location of myelolipomas, which should be considered for every fat-containing lesion detected in this region. The main clinical, imaging, and differential diagnoses of this entity are reviewed in this paper.
Research in Veterinary Science
A new selective medium, named LNIV-M, has been developed for isolation of Brucella suis. In this ... more A new selective medium, named LNIV-M, has been developed for isolation of Brucella suis. In this work, we evaluated the growth of B. suis reference and field strains from domestic pigs in different basal media and the susceptibility to different antibiotics contained in the currently used Farrell’s and modified Thayer-Martin media. We also determined the efficacy of LNIV-M and its diagnostic performance for isolating B. suis from wild boar tissue samples. A total of 1649 samples from 918 hunter-harvested wild boars were cultured in LNIV-M, Farrell’s and modified Thayer-Martin media. One hundred and thirty-nine (8.4%) samples from 63 (6.9%) animals resulted in a positive culture. LNIV-M detected 93.6% and 62.6% of positive animals and samples, respectively, while Farrell’s and modified Thayer-Martin media detected, respectively, 92.1% and 79.4% of positive animals and 58.3% and 59.7% of samples. These results confirm the adequate diagnostic performance of LNIV-M in the isolation of B. suis.
Applied Radiation and Isotopes, 1998
Historical radioanalytical data from the Institute of Radiation Protection and Dosimetry (IRD) na... more Historical radioanalytical data from the Institute of Radiation Protection and Dosimetry (IRD) national intercomparison program from 1991 to 1995 were analyzed to evaluate the performance of sixteen Brazilian laboratories in radionuclide analyses in environmental samples. Data are comprised of measurements of radionuclides in 435 spiked environmental samples distributed in fifteen intercomparison runs comprised of 955 analyses. The general and specific radionuclide performances of the participating laboratories were evaluated relative to the reference value. Data analysis encourages improvements in beta emitter measurements.
Journal of Geometry and Physics, 2011
We develop a notion of Einstein manifolds with skew torsion on compact, orientable Riemannian man... more We develop a notion of Einstein manifolds with skew torsion on compact, orientable Riemannian manifolds of dimension four. We prove an analogue of the Hitchin-Thorpe inequality and study the case of equality. We use the link with selfduality to study the moduli space of 1-instantons on S 4 for a family of metrics defined by Bonneau.
Extremophiles, 1999
In this study we characterized new strains of the slightly thermophilic species Rubrobacter radio... more In this study we characterized new strains of the slightly thermophilic species Rubrobacter radiotolerans and the thermophilic species Rubrobacter xylanophilus, both of which were previously represented only by the type strains isolated, respectively, from Japan and the United Kingdom. The new isolates were recovered from two hot springs in central Portugal after gamma irradiation of water and biofilm samples. We assessed biochemical characteristics, performed DNA–DNA hybridization, and carried out 16S rDNA sequence analysis to demonstrate that the new Rubrobacter isolates belong to the species R. radiotolerans and R. xylanophilus. We also show for the first time that the strains of R. xylanophilus and other strains of R. radiotolerans are extremely gamma radiation resistant.
Canadian Journal of Microbiology, 1994
.Alterations in total bacteria, iodonitrophenyltetrazolium (1NT)-positive bacteria, and heterotro... more .Alterations in total bacteria, iodonitrophenyltetrazolium (1NT)-positive bacteria, and heterotrophic plate counts of bottled mineral water. Can. J. Microbiol. 40: 72-77. The quantitative variation in the microflora in bottled mineral waters stored in polyvinyl chloride bottles was studied immediately after bottling and after 7 days storage, over 9 months. The microflora was determined by combining total counts using ethidium bromide, and the number ofiodonitrophenyltetrazolium (1NT)-positive cells determined with heterotrophic plate counts on R2A for prolonged incubation periods at 22 and 37°C. Immediately after bottling of mineral water A, the total counts with ethidium bromide varied between 70.0 and 495.0 bacterialml. The number of INT-positive bacteria varied between 14.0 and 40.0% counts. The heterotrophic plate counts were higher at 22°C than at 37OC and varied between 1. I and 13.2% and between 0.7 and 9.3% of the total counts. respectively. After 7 days storage, total bacterial counts increased by 1000 times, indicating multiplication of bacteria that were present in low numbers immediately after bottling. The percentage of INT-positive bacteria remained between 2.6 and 39.0% of the total counts but the number of culturable bacteria was higher than the number of INT-positive cells. Similar counts were found in other mineral waters (B, C, and D), but the numbers of INT-positive cells in two of them (B and D) were higher than the heterotrophic plate counts at 22°C. These results show the presence in the aquifer and (or) bottling system of a flora that is neither INT-positive nor culturable and reinforce previous results that still mineral waters have a large bacterial population after storage. Key w~orrls: mineral water, bacterial populations, ethidium bromide, INT, HPC. FERREIRA, A.-C., MORAIS, P.V., et DA COSTA, M.S. 1994. Alterations in total bacteria, iodonitrophenyltetrazolium (1NT)-positive bacteria, and heterotrophic plate counts of bottled mineral water. Can. J. Microbiol. 40 : 72-77. Les variations quantitatives de la flore bactirienne retrouvCe dans I'eau minCrale embouteillCe dans des contenants de chlorure de polyvinyle ont CtC CvaluCes aussitot aprks la mise en bouteilles et aprks 7 jours d'entreposage et ce pendant une pCriode d e 9 mois. Les valeurs ont CtC obtenues en additionnant les dCnombrements en prtsence de bromure d'Cthidium et le nombre decellules INT-positives avec le nombre des bactCries hCtCrotrophes sur R2A apr& incubation prolongCe i 37°C. ImmCdiatement aprks I'embouteillage de I'eau minCrale A, les dCnombrements en prCsence de bromure d'Cthidium variaient de 70 5 495 bactCrieslmL. Les bactCries INT-positives reprisentaient 14 k 40% des bactCries totales. Les dCcomptes des bactCries hCtCrotrophes Ctaient plus ClevCs 5 22°C qu'k 37°C et representaient respectivement 1,l i 13,2% et 0,7 i 9,3% des comptes totaux. Aprgs 7 jours d'entreposage, les comptes totaux augmentaient de 1000 fois confirmant la multiplication des bactCries prCsentes en faible quantitt lors de la mise en bouteilles. Pendant ce temps le pourcentage des bactCries INT-positives s'est lnaintenu entre 2,6 et 39,0% des bactCries totales mais le nombre des bactCries cultivables Ctait supCrieur au nombre de cellules INT-positives. Des comptes comparables ont Ct C observCs dans d'autres eaux minCrales (B. C et D) mais le nombre des cellules INT-positives de deux d e celles-ci (B et D) Ctait plus ClevC qlle le nombre d'hCtCrotrophes 5 22°C. Ces rksultats montrent la prCsence au niveau d e I'approvisionnement et (ou) du systkme d'embouteillage d'une flore bactCrienne qui est ni INT-positive ni cultivable et confirn~ent des rCsultats antCrieurs rCvClant la prCsence d'une population bactCrienne importante dans les eaux minerales entrepostes.
Veterinary Microbiology, 2006
Swine brucellosis is caused by the biovars 1, 2 and 3 of Brucella suis the identification of whic... more Swine brucellosis is caused by the biovars 1, 2 and 3 of Brucella suis the identification of which up to now relies on microbiological tests lacking adequate specificity together with time consuming and expensive molecular procedures. Based on sequence variation of the omp2b gene, we have developed a four primer set multiplex PCR assay that was tested for polymorphism analysis of B. suis biovars causing brucellosis in swine. The assay exploits the single nucleotide polymorphisms found in omp2b gene of B. suis reference biovars which are conserved in 43 B. suis field isolates from different geographic origins and hosts. Three specific amplification patterns (S1, S2 and S3) were obtained for reference strains of B. suis biovars 1, 2 and 3, respectively. However, some B. suis field isolates identified as biovars 2 or 3 according AMOS-PCR, PCR-RFLP of omp31 and omp2 genes and classical bacteriological methods, resulted also in S1 patterns, limiting the typing usefulness of the method.
Journal of Environmental Radioactivity, 2006
The Instituto de Radioproteção e Dosimetria has been coordinating the National Intercomparison Pr... more The Instituto de Radioproteção e Dosimetria has been coordinating the National Intercomparison Program (PNI) for 15 years, from 1991 to 2005. The objective is to evaluate the analytical performance of the laboratories in low-level activity concentration radionuclide assays in environmental samples. This work presents an evaluation of PNI data from 42 intercomparison runs, which distributed to 22 Brazilian laboratories 2511 samples evaluating 5768 radionuclide assays involving 32 radionuclides in the period from 1991 to 2004. The laboratory performance was evaluated using the Normalized Standard Deviation used by the U.S. EPA. For comparison aims, the Normalized Deviation, used by BIPM was also applied. Laboratory performance were grouped and evaluated in three periods of 5 years each. The first period shows, an average value of good performance of 71.2%, the second shows an average of 78.6% and the last an average of 82.3%. Performance for each kind of radionuclide is also presented.
Infection Genetics and Evolution, 2009
We demonstrate that the “HOOF-Print” assay provides high power to discriminate among Brucella iso... more We demonstrate that the “HOOF-Print” assay provides high power to discriminate among Brucella isolates collected on a small spatial scale (within Portugal). Additionally, we illustrate how haplotype identification using non-random association among markers allows resolution of B. melitensis biovars (1 and 3). We recommend that future studies use haplotype identification when analyzing multilocus population genetic data to help discriminate among microbial isolates such as Brucella.
Hemoglobin, 2005
Our aim was to assess the efficacy and safety of hydroxyurea (HU) in children with severe forms o... more Our aim was to assess the efficacy and safety of hydroxyurea (HU) in children with severe forms of sickle cell anemia followed in a Portuguese hospital. We carried out an open-label uncontrolled prospective study, which included children with severe forms of sickle cell anemia. Hydroxyurea was started at 15 mg/kg/day and increased to a maximum dose of 25 mg/kg/day. Patients were monitored to assess compliance, clinical and hematological response and toxicity. Nine children and adolescents, five girls and four boys, with a median age of 13 years (range 8 to 16) were enrolled in the study during a period of 24 months. All patients completed at least 15 months of therapy. Hb F was significantly increased, from a mean of 7.0 +/- 3.9% to 13.7 +/- 5.3% (p = 0.028). Clinically, all patients responded significantly with a reduction of 80% in the number of vaso-occlusive crises (VOC), 69% in hospital admissions, 76% in hospitalization days and 67% in transfusion requirements, without significant toxicity. We concluded that, in our population, HU proved to be effective in increasing Hb F levels, and in decreasing hospitalizations for VOC and transfusion requirements with no major side effects. Long-term clinical follow-up is important to certify benefit maintenance.
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Papers by Ana Cristina Ferreira