Correlates of facial expressions in the primary visual cortex

Face detection and recognition should be complemented by recognition of facial expression, for example for social robots which must react to human emotions. Our framework is based on two multi-scale representations in cortical area V1: keypoints at eyes, nose and mouth are grouped for face detection [1]; lines and edges provide information for face recognition [2].

Recognition of facial expressions by cortical multi-scale line and edge coding

Empirical studies concerning face recognition suggest that faces may be stored in memory by a few canonical representations. Models of visual perception are based on image representations in cortical area V1 and beyond, which contain many cell layers for feature extraction. Simple, complex and end-stopped cells provide input for line, edge and keypoint detection. Detected events provide a rich, multi-scale object representation, and this representation can be stored in memory in order to identify objects. In this paper, the above context is applied to face recognition. The multi-scale line/edge representation is explored in conjunction with keypoint-based saliency maps for Focus-of-Attention. Recognition rates of up to 96% were achieved by combining frontal and 3/4 views, and recognition was quite robust against partial occlusions.

Mathematica in the classroom: new tools for exploring precalculus and differential calculus

Prémio de Melhor Artigo de Jovem Investigador atribuído pela empresa Timberlake, apresentado na 1ª Conferência Nacional sobre Computação Simbólica no Ensino e na Investigação - CSEI2012, que decorreu no IST nos dias 2 e 3 de Abril.

Differential requirements of aPKC activity within different epithelial tissues

Epithelial tissues are essential during morphogenesis and organogenesis. During development, epithelial tissues undergo several different remodeling processes, from cell intercalation to cell change shape. An epithelial cell has a highly polarized structure, which is important to maintain tissue integrity. The mechanisms that regulate and maintain apicobasal polarity and epithelial integrity are mostly conserved among all species and in different tissues within the same organism. aPKC-PAR complex localizes in the apical domain of polarized cells, and its function is essential for apicobasal polarization and epithelial integrity. In this work we characterized two novel alleles of aPKC: a temperature sensitive allele (aPKCTS), which has a point mutation on a kinase domain, and another allele with a point mutation on a highly conserved amino acid within the PB1 domain of aPKC (aPKCPB1). Analysis of the aPKCTS mutant phenotypes, lead us to propose that during development different epithelial tissues have differential requirements of aPKC activity. More specifically, our work suggests de novo formation of adherens junctions (AJs) is particularly sensitive to sub-optimal levels of apkc activity. Analysis of the aPKCPB1 allele, suggests that aPKC is likely to have an apical structural function mostly independent of its kinase activity. Altogether our work suggests that although loss of aPKC function is associated to similar epithelial phenotypes (e.g., loss of apicobasal polarization and epithelial integrity), the requirements of aPKC activity within these tissues are nevertheless likely to vary.

Differential regulation of hippocampal neurogenesis by nitric oxide following seizures

The fact that the adult brain is able to produce new neurons or glial cells from neural stem cells (NSC) became one of the most interesting and challenging fields of research in neuroscience. Endogenous adult neurogenesis occurs in two main regions of the brain: the subventricular zone (SVZ) of the lateral ventricles and the subgranular zone (SGZ) in the dentate gyrus. Brain injury may be accompanied by increased neurogenesis, although neuroinflammation promotes the activation of microglial cells that can be detrimental to the neurogenic process. Nitric oxide (NO) is one of the factors released by microglia that can be proneurogenic. The mechanism by which NO promotes the proliferation of NSCs has been intensively studied. However, little is known about the role of NO in migration, survival and differentiation of the newborn cells. The aim of this work was to investigate the role of NO from inflammatory origin in proliferation, migration, differentiation and survival of NSCs from the dentate gyrus in a mouse model of status epilepticus. We also assessed neuroinflammation in the same injury model. Our work showed that NO increased proliferation of the early-born cells after seizures, but is detrimental for their survival. NO also increased migration of neuroblasts. Moreover, NO was important to maintain long-term neuroinflammation. Taken together, these results show that NO may be a good target to promote proliferation and migration of NSCs following seizures, but compromises survival of early-born cells.

Higher order derivatives and norms of certain matrix functions

Tese de doutoramento, Matemática (Álgebra Lógica e Fundamentos), Universidade de Lisboa, Faculdade de Ciências, 2014

Differential Benefit: Preschool Children, Quality of Early Childhood Education Environment and Developmental Gains Important for School Readiness

Thesis (Ph.D.)--University of Washington, 2014

Host-symbiont interactions in the deep-sea vent mussel Bathymodiolus azoricus : a molecular approach

Tese de Doutoramento, Ciências do Mar, especialidade de Biologia Marinha, 19 de Dezembro de 2015, Universidade dos Açores.

Automated design of microwave discrete tuning differential capacitance circuits in Si-integrated technologies

A genetic algorithm used to design radio-frequency binary-weighted differential switched capacitor arrays (RFDSCAs) is presented in this article. The algorithm provides a set of circuits all having the same maximum performance. This article also describes the design, implementation, and measurements results of a 0.25 lm BiCMOS 3-bit RFDSCA. The experimental results show that the circuit presents the expected performance up to 40 GHz. The similarity between the evolutionary solutions, circuit simulations, and measured results indicates that the genetic synthesis method is a very useful tool for designing optimum performance RFDSCAs.

Automated synthesis procedure of RF discrete tuning differential capacitance circuits

The paper presents a RFDSCA automated synthesis procedure. This algorithm determines several RFDSCA circuits from the top-level system specifications all with the same maximum performance. The genetic synthesis tool optimizes a fitness function proportional to the RFDSCA quality factor and uses the epsiv-concept and maximin sorting scheme to achieve a set of solutions well distributed along a non-dominated front. To confirm the results of the algorithm, three RFDSCAs were simulated in SpectreRF and one of them was implemented and tested. The design used a 0.25 mum BiCMOS process. All the results (synthesized, simulated and measured) are very close, which indicate that the genetic synthesis method is a very useful tool to design optimum performance RFDSCAs.

Avian infectious bronchitis virus (IBV): differential pathological and immunological profiles of two Brazilian variants.

2015

Differential effects of two anti-apo-cytochrome c-specific monoclonal antibodies on the function of apo-cytochrome c-specific murine T cell clones.

A murine monoclonal antibody (SJL 2-4) specific for the antigen apo-cytochrome c was shown to inhibit both antigen-induced proliferation and lymphokine secretion by an apo-cytochrome c-specific BALB/c helper T cell clone. The inhibition was specific because additional apo-cytochrome c-specific T cell clones were not inhibited by the same monoclonal antibody. Time course studies of the inhibition indicated that the initial 8 hr of contact between T cell clones and antigen-presenting cells were critical for activation of the T cell clones. Inhibition of T cell functions by antigen-specific antibodies appeared to correlate with the antibody-antigen binding constant because a second monoclonal antibody (Cyt-1-59), with identical specificity but with a lower affinity constant for apo-cytochrome c, had very little inhibitory effect on the proliferation or lymphokine secretion of apo-cytochrome c-specific T cell clones.

Differential effect of long versus short wavelength light exposure on pupillary re-dilation in patients with outer retinal disease.

BACKGROUND: In patients with outer retinal degeneration, a differential pupil response to long wavelength (red) versus short wavelength (blue) light stimulation has been previously observed. The goal of this study was to quantify differences in the pupillary re-dilation following exposure to red versus blue light in patients with outer retinal disease and compare them with patients with optic neuropathy and with healthy subjects. DESIGN: Prospective comparative cohort study. PARTICIPANTS: Twenty-three patients with outer retinal disease, 13 patients with optic neuropathy and 14 normal subjects. METHODS: Subjects were tested using continuous red and blue light stimulation at three intensities (1, 10 and 100 cd/m2) for 13 s per intensity. Pupillary re-dilation dynamics following the brightest intensity was analysed and compared between the three groups. MAIN OUTCOME MEASURES: The parameters of pupil re-dilation used in this study were: time to recover 90% of baseline size; mean pupil size at early and late phases of re-dilation; and differential re-dilation time for blue versus red light. RESULTS: Patients with outer retinal disease showed a pupil that tended to stay smaller after light termination and thus had a longer time to recovery. The differential re-dilation time was significantly greater in patients with outer retinal disease (median = 28.0 s, P < 0.0001) compared with controls and patients with optic neuropathy. CONCLUSIONS: A differential response of pupil re-dilation following red versus blue light stimulation is present in patients with outer retinal disease but is not found in normal eyes or among patients with visual loss from optic neuropathy.

Differential regulations of AQP4 and Kir4.1 by triamcinolone acetonide and dexamethasone in the healthy and inflamed retina.

PURPOSE: Glucocorticoids are used to treat macular edema, although the mechanisms underlying this effect remain largely unknown. The authors have evaluated in the normal and endotoxin-induced uveitis (EIU) rats, the effects of dexamethasone (dex) and triamcinolone acetonide (TA) on potassium channel Kir4.1 and aquaporin-4 (AQP4), the two main retinal Müller glial (RMG) channels controlling retinal fluid movement. METHODS: Clinical as well as relatively low doses of dex and TA were injected in the vitreous of normal rats to evaluate their influence on Kir4.1 and AQP4 expression 24 hours later. The dose-dependent effects of the two glucocorticoids were investigated using rat neuroretinal organotypic cultures. EIU was induced by footpad lipopolysaccharide injection, without or with 100 nM intraocular dex or TA. Glucocorticoid receptor and channel expression levels were measured by quantitative PCR, Western blot, and immunohistochemistry. RESULTS: The authors found that dex and TA exert distinct and specific channel regulations at 24 hours after intravitreous injection. Dex selectively upregulated Kir4.1 (not AQP4) in healthy and inflamed retinas, whereas TA induced AQP4 (not Kir4.1) downregulation in normal retina and upregulation in EIU. The lower concentration (100 nM) efficiently regulated the channels. Moreover, in EIU, an inflammatory condition, the glucocorticoid receptor was downregulated in the retina, which was prevented by intravitreous injections of the low concentration of dex or TA. CONCLUSIONS: The results show that dex and TA are far from being equivalent to modulate RMG channels. Furthermore, the authors suggest that low doses of glucocorticoids may have antiedematous effects on the retina with reduced toxicity.