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1.
PLoS One ; 19(3): e0300891, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38547212

RESUMO

OBJECTIVES: Estimate the effects of non-pharmacological interventions used to prevent the spread of COVID-19 on the quality of life, measured by Quality Adjusted Life Years (QALYs). METHODS: A survey on 1,506 heads of households from Chile in May of 2022. Respondents were asked basic socioeconomic questions and a version of the EQ-5D-5L questionnaire that was used to calculate the evolution of HRQoLs. Comparisons of means in HRQoLs measures before the pandemic, at the peak of restrictions, and at the moment of the survey were performed. RESULTS: The average HRQoL of the population before the pandemic was similar to other countries in the region (0.96). At the peak of restrictions (June 2020-August 2021), the average HRQoL decreased to 0.87 (-9%). At the time of survey (May 2022), the average HQRoL was 0.91 (4%). Assuming the recovery trend continued, pre-pandemic HRQoLs would be reached by January 2024. Altogether, the pandemic would have reduced QALYs by 0.2 in average. The effect is larger and the recovery slower among women. Our estimates imply that the restrictions to manage the pandemic came at a cost of 2.4 months of life years for the average (surviving) person, 1.8 months for men and 3.4 for women. CONCLUSIONS: Our results suggest that COVID-19 had worse effects on life quality than previously thought. These effects are more significant among women than among men. Efforts to improve life quality and speed up its recovery could have large positive consequences for the population.


Assuntos
COVID-19 , Qualidade de Vida , Masculino , Humanos , Feminino , Anos de Vida Ajustados por Qualidade de Vida , Pandemias , COVID-19/epidemiologia , COVID-19/prevenção & controle , Inquéritos e Questionários , Nível de Saúde
2.
Chem Soc Rev ; 52(4): 1288-1330, 2023 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-36744431

RESUMO

The post-graphene era is undoubtedly marked by two-dimensional (2D) materials such as quasi-van der Waals antimonene. This emerging material has a fascinating structure, exhibits a pronounced chemical reactivity (in contrast to graphene), possesses outstanding electronic properties and has been postulated for a plethora of applications. However, chemistry and physics of antimonene remain in their infancy, but fortunately recent discoveries have shed light on its unmatched allotropy and rich chemical reactivity offering a myriad of unprecedented possibilities in terms of fundamental studies and applications. Indeed, antimonene can be considered as one of the most appealing post-graphene 2D materials reported to date, since its structure, properties and applications can be chemically engineered from the ground up (both using top-down and bottom-up approaches), offering an unprecedented level of control in the realm of 2D materials. In this review, we provide an in-depth analysis of the recent advances in the synthesis, characterization and applications of antimonene. First, we start with a general introduction to antimonene, and then we focus on its general chemistry, physical properties, characterization and synthetic strategies. We then perform a comprehensive study on the allotropy, the phase transition mechanisms, the oxidation behaviour and chemical functionalization. From a technological point of view, we further discuss the applications recently reported for antimonene in the fields of optoelectronics, catalysis, energy storage, cancer therapy and sensing. Finally, important aspects such as new scalable methodologies or the promising perspectives in biomedicine are discussed, pinpointing antimonene as a cutting-edge material of broad interest for researchers working in chemistry, physics, materials science and biomedicine.

3.
J Org Chem ; 88(1): 18-26, 2023 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-35584367

RESUMO

The synthesis of cis-alkenes is industrially carried out by selective semi-hydrogenation of alkynes with complex Pd catalysts, which include the Lindlar catalyst (PdPb on CaCO3) and c-Pd/TiS (colloidal ligand-protected Pd nanoparticles), among others. Here, we show that Pd0 atoms are generated from primary Pd salts (PdCl2, PdSO4, Pd(OH)2, PdO) with H2 in alcohol solutions, independently of the alkyne, to catalyze the semi-hydrogenation reaction with extraordinarily high efficiency (up to 735 s-1), yield (up to 99%), and selectivity (up to 99%). The easy-to-prepare Pd0 species hold other potential catalytic applications.

4.
Chemistry ; 26(29): 6504-6517, 2020 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-32053228

RESUMO

Layered double hydroxides (LDHs) are a class of 2D anionic materials exhibiting wide chemical versatility and promising applications in different fields, ranging from catalysis to energy storage and conversion. However, the covalent chemistry of this kind of 2D materials is still barely explored. Herein, the covalent functionalization with silanes of a magnetic NiFe-LDH is reported. The synthetic route consists of a topochemical approach followed by anion exchange reaction with surfactant molecules prior to covalent functionalization with the (3-aminopropyl)triethoxysilane (APTES) molecules. The functionalized NiFe-APTES was fully characterized by X-ray diffraction, infrared spectroscopy, electron microscopy, thermogravimetric analysis coupled with mass spectrometry and 29 Si solid-state nuclear magnetic resonance, among others. The effect on the electronic properties of the functionalized LDH was investigated by a magnetic study in combination with Mössbauer spectroscopy. Moreover, the reversibility of the silane-functionalization at basic pH was demonstrated, and the quality of the resulting LDH was proven by studying the electrochemical performance in the oxygen evolution reaction in basic media. Furthermore, the anion exchange capability for the NiFe-APTES was tested employing CrVI , resulting in an increase of 200 % of the anion retention. This report allows for a new degree of tunability of LDHs, opening the door to the synthesis of new hybrid architectures and materials.

5.
Nat Commun ; 10(1): 3132, 2019 Jul 11.
Artigo em Inglês | MEDLINE | ID: mdl-31296848

RESUMO

The original version of this Comment contained errors in the legend of Figure 2, in which the locations of the fifteenth and sixteenth GBA members were incorrectly given as '(15) Australian Genome Foundry, Macquarie University; (16) Australian Foundry for Advanced Biomanufacturing, University of Queensland.'. The correct version replaces this with '(15) Australian Foundry for Advanced Biomanufacturing (AusFAB), University of Queensland and (16) Australian Genome Foundry, Macquarie University'. This has been corrected in both the PDF and HTML versions of the Comment.

7.
Chem Commun (Camb) ; 55(23): 3315-3318, 2019 Mar 14.
Artigo em Inglês | MEDLINE | ID: mdl-30756105

RESUMO

Direct exfoliation of a carbonate layered double hydroxide (LDH) has been achieved by using a novel horn-probe sonic tip, avoiding the development of time-consuming anion-exchange reactions. The most suitable solvents were chosen based on the Hildebrand solubility parameters and the thickness of the exfoliated nanosheets confirmed unambiguously the successful delamination.

8.
Inorg Chem ; 57(4): 2013-2022, 2018 Feb 19.
Artigo em Inglês | MEDLINE | ID: mdl-29419288

RESUMO

Layered double hydroxides (LDHs) exhibit unparalleled anion exchange properties and the ability to be exfoliated into 2D nanosheets, which can be used as a building block to fabricate a wide variety of hybrid functional nanostructured materials. Still, if one wants to use LDHs as a magnetic building blocks in the design of complex architectures, the role played by the dipolar magnetic interactions in these layered materials needs to be understood. In this work, we synthesized and characterized a five-membered CoAl-LDH series with basal spacing ranging from 7.5 to 34 Å. A detailed experimental characterization allows us to conclude that the main factor governing the dipolar interactions between magnetic layers cannot be the interlayer spacing. Supporting theoretical modeling suggests instead a relevant role for spin correlation size, which, in the limit, is related to the lateral dimension of the layer. These results highlight the importance of cation ordering in the magnetic behavior of LDHs, and underpin the differences with homometallic-layered hydroxides.

9.
Phys Rev E ; 95(1-1): 012129, 2017 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-28208401

RESUMO

We study the critical behavior and the ground-state entanglement of a large class of su(1|1) supersymmetric spin chains with a general (not necessarily monotonic) dispersion relation. We show that this class includes several relevant models, with both short- and long-range interactions of a simple form. We determine the low temperature behavior of the free energy per spin, and deduce that the models considered have a critical phase in the same universality class as a (1+1)-dimensional conformal field theory (CFT) with central charge equal to the number of connected components of the Fermi sea. We also study the Rényi entanglement entropy of the ground state, deriving its asymptotic behavior as the block size tends to infinity. In particular, we show that this entropy exhibits the logarithmic growth characteristic of (1+1)-dimensional CFTs and one-dimensional (fermionic) critical lattice models, with a central charge consistent with the low-temperature behavior of the free energy. Our results confirm the widely believed conjecture that the critical behavior of fermionic lattice models is completely determined by the topology of their Fermi surface.

10.
Int J Comput Assist Radiol Surg ; 12(12): 2055-2067, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-28188486

RESUMO

PURPOSE: In 2005, an application for surgical planning called AYRA[Formula: see text] was designed and validated by different surgeons and engineers at the Virgen del Rocío University Hospital, Seville (Spain). However, the segmentation methods included in AYRA and in other surgical planning applications are not able to segment accurately tumors that appear in soft tissue. The aims of this paper are to offer an exhaustive validation of an accurate semiautomatic segmentation tool to delimitate retroperitoneal tumors from CT images and to aid physicians in planning both radiotherapy doses and surgery. METHODS: A panel of 6 experts manually segmented 11 cases of tumors, and the segmentation results were compared exhaustively with: the results provided by a surgical planning tool (AYRA), the segmentations obtained using a radiotherapy treatment planning system (Pinnacle[Formula: see text]), the segmentation results obtained by a group of experts in the delimitation of retroperitoneal tumors and the segmentation results using the algorithm under validation. RESULTS: 11 cases of retroperitoneal tumors were tested. The proposed algorithm provided accurate results regarding the segmentation of the tumor. Moreover, the algorithm requires minimal computational time-an average of 90.5% less than that required when manually contouring the same tumor. CONCLUSION: A method developed for the semiautomatic selection of retroperitoneal tumor has been validated in depth. AYRA, as well as other surgical and radiotherapy planning tools, could be greatly improved by including this algorithm.


Assuntos
Algoritmos , Imageamento Tridimensional/métodos , Planejamento da Radioterapia Assistida por Computador/métodos , Neoplasias Retroperitoneais/diagnóstico , Adolescente , Adulto , Humanos , Masculino , Neoplasias Retroperitoneais/terapia , Tomografia Computadorizada por Raios X , Adulto Jovem
11.
Phys Rev E ; 93(6): 062103, 2016 06.
Artigo em Inglês | MEDLINE | ID: mdl-27415204

RESUMO

We introduce a general class of su(1|1) supersymmetric spin chains with long-range interactions which includes as particular cases the su(1|1) Inozemtsev (elliptic) and Haldane-Shastry chains, as well as the XX model. We show that this class of models can be fermionized with the help of the algebraic properties of the su(1|1) permutation operator and take advantage of this fact to analyze their quantum criticality when a chemical potential term is present in the Hamiltonian. We first study the low-energy excitations and the low-temperature behavior of the free energy, which coincides with that of a (1+1)-dimensional conformal field theory (CFT) with central charge c=1 when the chemical potential lies in the critical interval (0,E(π)), E(p) being the dispersion relation. We also analyze the von Neumann and Rényi ground state entanglement entropies, showing that they exhibit the logarithmic scaling with the size of the block of spins characteristic of a one-boson (1+1)-dimensional CFT. Our results thus show that the models under study are quantum critical when the chemical potential belongs to the critical interval, with central charge c=1. From the analysis of the fermion density at zero temperature, we also conclude that there is a quantum phase transition at both ends of the critical interval. This is further confirmed by the behavior of the fermion density at finite temperature, which is studied analytically (at low temperature), as well as numerically for the su(1|1) elliptic chain.

12.
Infect Immun ; 83(1): 161-72, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25332120

RESUMO

Live attenuated bacteria hold great promise as multivalent mucosal vaccines against a variety of pathogens. A major challenge of this approach has been the successful delivery of sufficient amounts of vaccine antigens to adequately prime the immune system without overattenuating the live vaccine. Here we used a live attenuated Salmonella enterica serovar Typhi strain to create a bivalent mucosal plague vaccine that produces both the protective F1 capsular antigen of Yersinia pestis and the LcrV protein required for secretion of virulence effector proteins. To reduce the metabolic burden associated with the coexpression of F1 and LcrV within the live vector, we balanced expression of both antigens by combining plasmid-based expression of F1 with chromosomal expression of LcrV from three independent loci. The immunogenicity and protective efficacy of this novel vaccine were assessed in mice by using a heterologous prime-boost immunization strategy and compared to those of a conventional strain in which F1 and LcrV were expressed from a single low-copy-number plasmid. The serum antibody responses to lipopolysaccharide (LPS) induced by the optimized bivalent vaccine were indistinguishable from those elicited by the parent strain, suggesting an adequate immunogenic capacity maintained through preservation of bacterial fitness; in contrast, LPS titers were 10-fold lower in mice immunized with the conventional vaccine strain. Importantly, mice receiving the optimized bivalent vaccine were fully protected against lethal pulmonary challenge. These results demonstrate the feasibility of distributing foreign antigen expression across both chromosomal and plasmid locations within a single vaccine organism for induction of protective immunity.


Assuntos
Portadores de Fármacos , Vacina contra a Peste/imunologia , Peste/prevenção & controle , Salmonella typhi/genética , Animais , Anticorpos Antibacterianos/sangue , Antígenos de Bactérias/genética , Antígenos de Bactérias/imunologia , Proteínas de Bactérias/genética , Proteínas de Bactérias/imunologia , Modelos Animais de Doenças , Vetores Genéticos , Camundongos Endogâmicos BALB C , Peste/imunologia , Vacina contra a Peste/administração & dosagem , Vacina contra a Peste/genética , Proteínas Citotóxicas Formadoras de Poros/genética , Proteínas Citotóxicas Formadoras de Poros/imunologia , Análise de Sobrevida , Vacinação/métodos , Vacinas Atenuadas/administração & dosagem , Vacinas Atenuadas/genética , Vacinas Atenuadas/imunologia , Vacinas Sintéticas/administração & dosagem , Vacinas Sintéticas/genética , Vacinas Sintéticas/imunologia
13.
Inorg Chem ; 52(14): 7828-30, 2013 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-23795549

RESUMO

Some recent reports claiming room temperature spontaneous magnetization in layered double hydroxides (LDHs) have been published; however, the reported materials cause serious concern as to whether this cooperative magnetic behavior comes from extrinsic sources, such as spinel iron oxide nanoparticles. The syntheses of crystalline Fe(3+)-based LDHs with and without impurities have been developed, highlighting the care that must be taken during the synthetic process in order to avoid misidentification of magnetic LDHs.

14.
Cell Microbiol ; 15(4): 619-46, 2013 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-23107293

RESUMO

Toxoplasma and Chlamydia trachomatis are obligate intracellular pathogens that have evolved analogous strategies to replicate within mammalian cells. Both pathogens are known to extensively remodel the cytoskeleton, and to recruit endocytic and exocytic organelles to their respective vacuoles. However, how important these activities are for infectivity by either pathogen remains elusive. Here, we have developed a novel co-infection system to gain insights into the developmental cycles of Toxoplasma and C. trachomatis by infecting human cells with both pathogens, and examining their respective ability to replicate and scavenge nutrients. We hypothesize that the common strategies used by Toxoplasma and Chlamydia to achieve development results in direct competition of the two pathogens for the same pool of nutrients. We show that a single human cell can harbour Chlamydia and Toxoplasma. In co-infected cells, Toxoplasma is able to divert the content of host organelles, such as cholesterol. Consequently, the infectious cycle of Toxoplasma progresses unimpeded. In contrast, Chlamydia's ability to scavenge selected nutrients is diminished, and the bacterium shifts to a stress-induced persistent growth. Parasite killing engenders an ordered return to normal chlamydial development. We demonstrate that C. trachomatis enters a stress-induced persistence phenotype as a direct result from being barred from its normal nutrient supplies as addition of excess nutrients, e.g. amino acids, leads to substantial recovery of Chlamydia growth and infectivity. Co-infection of C. trachomatis with slow growing strains of Toxoplasma or a mutant impaired in nutrient acquisition does not restrict chlamydial development. Conversely, Toxoplasma growth is halted in cells infected with the highly virulent Chlamydia psittaci. This study illustrates the key role that cellular remodelling plays in the exploitation of host intracellular resources by Toxoplasma and Chlamydia. It further highlights the delicate balance between success and failure of infection by intracellular pathogens in a co-infection system at the cellular level.


Assuntos
Chlamydia trachomatis/crescimento & desenvolvimento , Chlamydia trachomatis/metabolismo , Alimentos , Toxoplasma/crescimento & desenvolvimento , Toxoplasma/metabolismo , Células Cultivadas , Humanos , Interações Microbianas , Estresse Fisiológico
15.
Eukaryot Cell ; 12(2): 265-77, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23243063

RESUMO

The prokaryote Chlamydia trachomatis and the protozoan Toxoplasma gondii, two obligate intracellular pathogens of humans, have evolved a similar modus operandi to colonize their host cell and salvage nutrients from organelles. In order to gain fundamental knowledge on the pathogenicity of these microorganisms, we have established a cell culture model whereby single fibroblasts are coinfected by C. trachomatis and T. gondii. We previously reported that the two pathogens compete for the same nutrient pools in coinfected cells and that Toxoplasma holds a significant competitive advantage over Chlamydia. Here we have expanded our coinfection studies by examining the respective abilities of Chlamydia and Toxoplasma to co-opt the host cytoskeleton and recruit organelles. We demonstrate that the two pathogen-containing vacuoles migrate independently to the host perinuclear region and rearrange the host microtubular network around each vacuole. However, Toxoplasma outcompetes Chlamydia to the host microtubule-organizing center to the detriment of the bacterium, which then shifts to a stress-induced persistent state. Solely in cells preinfected with Chlamydia, the centrosomes become associated with the chlamydial inclusion, while the Toxoplasma parasitophorous vacuole displays growth defects. Both pathogens fragment the host Golgi apparatus and recruit Golgi elements to retrieve sphingolipids. This study demonstrates that the productive infection by both Chlamydia and Toxoplasma depends on the capability of each pathogen to successfully adhere to a finely tuned developmental program that aims to remodel the host cell for the pathogen's benefit. In particular, this investigation emphasizes the essentiality of host organelle interception by intravacuolar pathogens to facilitate access to nutrients.


Assuntos
Infecções por Chlamydia/microbiologia , Chlamydia/fisiologia , Toxoplasma/fisiologia , Toxoplasmose/parasitologia , Células Cultivadas , Centrossomo/metabolismo , Centrossomo/microbiologia , Centrossomo/parasitologia , Ceramidas/metabolismo , Infecções por Chlamydia/parasitologia , Infecções por Chlamydia/patologia , Coinfecção , Fibroblastos/microbiologia , Fibroblastos/parasitologia , Fibroblastos/patologia , Complexo de Golgi/microbiologia , Complexo de Golgi/parasitologia , Complexo de Golgi/patologia , Interações Hospedeiro-Parasita , Interações Hospedeiro-Patógeno , Humanos , Membranas Intracelulares/metabolismo , Membranas Intracelulares/microbiologia , Membranas Intracelulares/parasitologia , Viabilidade Microbiana , Microtúbulos/metabolismo , Microtúbulos/microbiologia , Microtúbulos/parasitologia , Mitocôndrias/microbiologia , Mitocôndrias/parasitologia , Mitocôndrias/patologia , Toxoplasmose/microbiologia , Toxoplasmose/patologia , Vacúolos/microbiologia , Vacúolos/parasitologia
16.
Educ. méd. (Ed. impr.) ; 15(1): 37-46, mar. 2012. ilus, tab
Artigo em Espanhol | IBECS | ID: ibc-105133

RESUMO

Introducción. El Real Decreto 183/2008 destaca la importancia de la evaluación formativa en el sistema de residencia para la formación especializada. En evaluación formativa lo importante es el feedback producido sobre el que aprende y el que enseña, contribuyendo así a la mejora del proceso enseñanza-aprendizaje. Una parte esencial de la evaluación formativa es la pregunta directa a los sujetos a quienes se dirige la formación. Sujetos y métodos. Desde junio de 2007, los residentes del hospital cumplimentan un cuestionario de 37 preguntas cerradas y una abierta, en la que se les solicitaba su opinión sobre aspectos de la formación recibida en el año precedente. Analizamos los cuestionarios de tres años (266 encuestas analizadas). Resultados. Las guardias y las urgencias en general se perciben como un problema y como un lugar donde hay una importante área de mejora. Otras importantes áreas de mejora son la capacitación del residente para optimizar el acceso a fuentes de información y una mayor participación e implicación en investigación. Conclusiones. Estudios como el descrito deben servir para implantar acciones eficientes orientadas a mejorar las deficiencias observadas en la formación de residentes. Ha de ser punto de referencia para conocer la evolución del proceso formativo en nuestro centro. Si no se realizan este tipo de estudios es difícil conocer los progresos o deficiencias que, desde el punto de vista de quien aprende, tienen lugar en un determinado ámbito de la formación de especialistas en ciencias de la salud (AU)


Introduction. The Royal Decree 183/2008 highlights the relevance of the formative assessment in the residence system for specialist training. In formative assessment, the most important is the feedback between learner and teacher, contributing so to the continuous improvement in teach-learning process. An essential part of the formative assessment is the direct ask posed to whom the formation is directed. Subjects and methods. Since June 2007, the residents filled a survey which includes 37 closed questions, and an one open question. In this questionnaire we expect their opinion about aspects in the education received in the past year. We analyzed the questionnaires of three years (total 266 surveys were analyzed). Results. Medical guards and emergency area were perceived as an important problem, as a place for improvement. Other relevant areas for improvement were the training for residents’ ability for effective bibliographic researches, and greater involvement in research activities. Conclusions. Studies like these should be used to implement efficient actions aimed to detect problems and to improve deficiencies in residents’ training. It has to be a reference point for following the learning evolution process in our center. Failure to make such studies it will be difficult to know the progress or deficiencies, from the learner standpoint, that take place in a particular area of training of specialists in health sciences (AU)


Assuntos
Humanos , Satisfação Pessoal , Educação Médica/estatística & dados numéricos , Internato e Residência/classificação , Avaliação Educacional/métodos , Especialização/tendências , Serviços de Integração Docente-Assistencial
17.
Cell Microbiol ; 13(7): 1014-25, 2011 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-21504531

RESUMO

Late Chlamydia trachomatis inclusions express each member of the surface-exposed polymorphic membrane protein family (Pmp subtypes A through I) with a reproducible distribution of fully-on, fully-off and intermediate phenotypes. This observation is consistent with observed variable Pmp antibody profiles in C. trachomatis-infected patients and has led to the hypothesis that the pmp gene family forms the basis of a phase variation-like mechanism of antigenic variation. Here we investigate and compare the developmental expression of each of the nine pmp genes under conditions of optimal in vitro growth with that under conditions that promote prolonged survival of chlamydiae when exposed to penicillin-induced stress. We demonstrate that the pmp gene family includes distinct transcriptional units that are differentially expressed along development and differentially responsive to stress. In particular, our results indicate that expression of pmpA, pmpD and pmpI is uniquely unaffected by stress, suggesting that the PmpA, PmpD and PmpI proteins play a critical role in the pathogenesis of C. trachomatis.


Assuntos
Chlamydia trachomatis/efeitos dos fármacos , Chlamydia trachomatis/metabolismo , Expressão Gênica , Proteínas de Membrana/biossíntese , Penicilinas/toxicidade , Estresse Fisiológico , Perfilação da Expressão Gênica , Humanos , Transcrição Gênica
18.
Front Neurosci ; 5: 26, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21442012

RESUMO

In this paper we present a very exciting overlap between emergent nanotechnology and neuroscience, which has been discovered by neuromorphic engineers. Specifically, we are linking one type of memristor nanotechnology devices to the biological synaptic update rule known as spike-time-dependent-plasticity (STDP) found in real biological synapses. Understanding this link allows neuromorphic engineers to develop circuit architectures that use this type of memristors to artificially emulate parts of the visual cortex. We focus on the type of memristors referred to as voltage or flux driven memristors and focus our discussions on a behavioral macro-model for such devices. The implementations result in fully asynchronous architectures with neurons sending their action potentials not only forward but also backward. One critical aspect is to use neurons that generate spikes of specific shapes. We will see how by changing the shapes of the neuron action potential spikes we can tune and manipulate the STDP learning rules for both excitatory and inhibitory synapses. We will see how neurons and memristors can be interconnected to achieve large scale spiking learning systems, that follow a type of multiplicative STDP learning rule. We will briefly extend the architectures to use three-terminal transistors with similar memristive behavior. We will illustrate how a V1 visual cortex layer can assembled and how it is capable of learning to extract orientations from visual data coming from a real artificial CMOS spiking retina observing real life scenes. Finally, we will discuss limitations of currently available memristors. The results presented are based on behavioral simulations and do not take into account non-idealities of devices and interconnects. The aim of this paper is to present, in a tutorial manner, an initial framework for the possible development of fully asynchronous STDP learning neuromorphic architectures exploiting two or three-terminal memristive type devices. All files used for the simulations are made available through the journal web site.

19.
BMC Genomics ; 11: 442, 2010 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-20646324

RESUMO

BACKGROUND: Chlamydia pneumoniae is a widespread pathogen causing upper and lower respiratory tract infections in addition to a range of other diseases in humans and animals. Previous whole genome analyses have focused on four essentially clonal (> 99% identity) C. pneumoniae human genomes (AR39, CWL029, J138 and TW183), providing relatively little insight into strain diversity and evolution of this species. RESULTS: We performed individual gene-by-gene comparisons of the recently sequenced C. pneumoniae koala genome and four C. pneumoniae human genomes to identify species-specific genes, and more importantly, to gain an insight into the genetic diversity and evolution of the species. We selected genes dispersed throughout the chromosome, representing genes that were specific to C. pneumoniae, genes with a demonstrated role in chlamydial biology and/or pathogenicity (n = 49), genes encoding nucleotide salvage or amino acid biosynthesis proteins (n = 6), and extrachromosomal elements (9 plasmid and 2 bacteriophage genes). CONCLUSIONS: We have identified strain-specific differences and targets for detection of C. pneumoniae isolates from both human and animal origin. Such characterisation is necessary for an improved understanding of disease transmission and intervention.


Assuntos
Chlamydophila pneumoniae/genética , Variação Genética , Phascolarctidae/microbiologia , Adaptação Fisiológica , Aminoácidos/biossíntese , Animais , Infecções por Chlamydophila/diagnóstico , Infecções por Chlamydophila/epidemiologia , Infecções por Chlamydophila/terapia , Chlamydophila pneumoniae/metabolismo , Chlamydophila pneumoniae/patogenicidade , Cromossomos Bacterianos/metabolismo , Genes Bacterianos/genética , Humanos , Nucleotídeos/metabolismo , Especificidade da Espécie
20.
Cell Microbiol ; 12(2): 174-87, 2010 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-19811502

RESUMO

The hypothesized variable expression of polymorphic membrane proteins (PmpA-PmpI) in Chlamydia trachomatis-infected patients was tested by examination of the expression of each Pmp subtype in in vitro-grown C. trachomatis. A panel of monospecific polyclonal and monoclonal antibodies was used to demonstrate surface exposure of Pmps of each subtype by differential immunofluorescence (IF) with and without prior detergent permeabilization of paraformaldehyde-fixed inclusions and for selected Pmps by immunogold labelling. Although specific transcript was detected for each pmp gene late in development, IF experiments with Pmp subtype-specific antibodies reveal that a number of inclusions in a single infection do not express Pmps of a given subtype. Coexpression experiments suggest that pmp genes are shut off independently from one another in non-expressing inclusions, i.e. different inclusions are switched off for different Pmps. Overall, these studies establish the existence of an efficient shutoff mechanism independently affecting the expression of each member of the pmp gene family in in vitro-grown C. trachomatis. Like other paralogous gene families of bacterial pathogens, the pmp gene family of C. trachomatis may serve the critical dual function of a highly adaptable virulence factor also providing antigenic diversity in the face of the host adaptive immune response.


Assuntos
Proteínas de Bactérias/metabolismo , Chlamydia trachomatis/metabolismo , Regulação Bacteriana da Expressão Gênica , Proteínas de Membrana/metabolismo , Proteínas de Bactérias/genética , Chlamydia trachomatis/genética , Chlamydia trachomatis/ultraestrutura , Células HeLa , Humanos , Proteínas de Membrana/genética , Microscopia Eletrônica de Transmissão , Reação em Cadeia da Polimerase Via Transcriptase Reversa
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