Plant growth regulators and mobilization of reserves in imbibition phases of yellow passion fruit.

The production of seedlings of the passion fruit tree, usually, is sexual, and the seeds are not uniform in the seedling emergence, and soaking treatments of seeds can provide faster and more uniform germination. It was aimed to study the action of plant growth regulators and the mobilization of reserves in the stages of soaking of yellow passion fruit seeds. The seeds were soaked for five hours in solutions containing plant growth regulators, in a completely randomized design, in a factorial 8 x 4, with four replications. The first factor corresponds to eight plant growth regulators: T1 - distilled water (control); T2 - 6-benzylaminepurine ​​500 mg L-1; T3 - 4-(3-indolyl) butyric acid 500 mg L-1; T4 - gibberellic acid 500 mg L-1; T5 - spermine 250 mg L-1; T6 - spermine 750 mg L-1; T7 - spermidine 750 mg L-1; T8 - spermidine 1250 mg L-1; and the second factor, to the four soaking times: zero, four, 72 and 120 hours, corresponding, respectively, to the dry seed, and to phases I, II, and III of the imbibition curve. It was evaluated the biochemical composition of seeds (lipids, soluble sugars and starch). The seeds showed accumulation of lipids in phase III; the content of soluble sugars increased in phase I and decreased in phase II. The starch content increased until the phase II and decreased in phase III. Starch is the main reserve in the seeds and the main source of energy used in phase III; soaking the seeds in polyamines generates an accumulation of lipids in the seeds and soaking in plant growth regulators increases the burning of starch.

Potential of coffee straw biochal as a substrate conditioner in seed lettuce and sorghum germination and vigority.

The use of residues from coffee production to obtain biochar is a sustainable approach, which aims to minimize the environmental impact of these materials. In this study, the effect of adding coffee straw biochar on the physiological quality of lettuce and sorghum seeds was investigated. Thus, the objective of this work was to study the effect of adding different concentrations of coffee biochar in the substrate composition on the physiological quality of lettuce (Lactuca sativa) and sorghum (Sorghum bicolor) seeds. The experimental design used was completely randomized, with five concentrations of biochar (0; 7.5; 15; 30 and 60%), conducted with four replications of 25 seeds. The use of biochar in the concentrations studied does not provide an increase in the average germination percentage and vigor of lettuce and sorghum seeds. The increase in the concentration of biochar caused less seed vigor, suggesting a toxic effect. For seed germination, there was no significant difference between lettuce and sorghum species, regardless of treatment. For the germination speed index, sorghum seeds have higher means, except for the treatment with the addition of 15% coffee straw biochar. Lettuce seeds have higher shoot length averages, except for treatment with 100% commercial substrate. The sorghum seeds have higher mean root length and dry mass than lettuce, regardless of the treatment.

Maturation and harvest time of Ateleia glazioveana Baill. seeds.

Ateleia glazioveana Baill. is a pioneer, rustic and can be used for forest recovery. This work aimed to study the process of physiological maturation of this species. The research was carried out in the city of Alegre - ES, the trees were identified in the floral anthesis and accompanied during the filling of the fruits and development of the seeds until the complete maturation. The fruits were harvested at the following stages 7, 14, 21, 28, 35 and 42 days after anthesis, and characterized according to: morphometry, moisture, fresh and dry mass of fruits and seeds, germination, germination speed index, shoot and root length and dry mass of seedlings. The regression equations were adjusted for the main characteristics analyzed as a function of the harvest period. The point of physiological maturity of timbó occurred at 42 days after anthesis.

Multivariate analysis of agronomic, physicochemical, and physiological characters of passion fruit hybrids cultivated at different environments.

Simultaneous analysis studies of several agronomic traits in cultivated plants make it possible to identify phenotypic and genotypic differences due to environmental variations, such as altitude. Therefore, the objective was to evaluate, through multivariate analysis of agronomic, physicochemical and physiological characters, passion fruit hybrids cultivated in different environments. The hybrids used were Gigante Amarelo, Rubi do Cerrado and Sol do Cerrado, cultivated in the southern region of Espírito Santo in four municipalities/environments: Marataízes (41 m), Jerônimo Monteiro (104 m), Alegre (711 m), and Ibitirama (1016 m). The agronomic characters of the plants, the physical-chemical characteristics of the fruits and the physical, biochemical and physiological qualities of the seeds were analyzed. The Singh method was used to determine the most important differentiating characters between hybrids growing in different environments. Based on these characters, a dissimilarity matrix was generated and a principal coordinate analysis was performed. It was observed that the pulp yield was influenced by altitude. The three hybrids showed greater performance in terms of agronomic characters at altitude (41 m) than at altitude (104 m). The Sol do Cerrado hybrid showed high performance in the physical-chemical characteristics of the fruits at altitude (104 m).

Synovial fluid and radiographic evaluation of joints from dogs with visceral leishmaniasis.

BACKGROUND: Polyarthritis has been associated with canine visceral leishmaniasis (CanVL), and co-infection with Ehrlichia canis is common and may alter clinical manifestations. METHODS: A total of 89 dogs presenting CanVL were subdivided into two groups: (1) G1, consisting of 46 dogs seronegative to Ehrlichia spp., and (ii) G2, consisting of 43 dogs seropositive to Ehrlichia spp. Eight joints (carpal, tarsal, stifles and elbows) from each dog were evaluated by radiography and synovial fluid (SF) cytologic analysis. RESULTS: Overall, 74 of the 89 (83.1%) dogs presented joint abnormalities suggestive of osteoarthritis by radiography (G1: 40/46 [86.9%]; G2: 34/43 [79.0%]), with no statistically significant between-group difference. All dogs with abnormal joint X-ray images presented radiographic lesions bilaterally, independent of the characteristics of the lesion. Soft tissue swelling around the joint and joint space narrowing were more commonly observed in G1 than in G2 dogs. There was no significant between-group difference in terms of other radiographic abnormalities suggestive of osteoarthritis (evident trabecular pattern, subchondral bone sclerosis, osteolysis, osteolytic-proliferative lesions or bone proliferation). SF from 174/315 (55.2%) and 152/307 (49.5%) joints from G1 and G2 dogs, respectively, presented an inflammatory infiltrate, but there was no significant association between the presence of inflammatory infiltrate and group. There was also no statistical difference between groups in either of the evaluated joints in terms of the percentage of neutrophils or mononuclear cells. Leishmania spp. amastigotes were found in 69/315 (21.9%) joints from G1 dogs and in 100/307 (32.5%) joints from G2 dogs (Fisher's exact test, P = 0.002, odds ratio = 0.5, 95% confidence interval = 0.4-0.8). The neutrophilic infiltrate was significantly higher in joints with amastigote forms in both G1 (Mann-Whitney U-test, U(18) = 817, Z = -3.76, P = 0.0001) and G2 dogs (Mann-Whitney U-test, U(18) = 6543, Z = - 5.06, P < 0.0001). CONCLUSIONS: A high prevalence of arthritis in dogs with CanVL was found, and all dogs presented involvement in multiple joints. Although no difference was observed between groups in terms of the number of dogs with polyarthritis and the presence of an inflammatory infiltrate in SF, Leishmania spp. amastigotes were found more frequently in joints from G2 dogs. Further studies evaluating SF in dogs co-infected with L. infantum and E. canis should be performed to evaluate this finding.

Malformações em pequenos ruminantes no semiárido da Bahia: aspectos epidemiológicos, clínico-patológicos e radiológicos / Malformations in small ruminants in the semi-arid region of Bahia: epidemiological, clinical-pathological and radiological aspects

O objetivo do presente trabalho é descrever os principais aspectos epidemiológicos, clínico-patológicos e radiológicos de malformações em pequenos ruminantes no semiárido do estado da Bahia. Foram realizadas visitas técnicas em 41 propriedades rurais no município de Uauá, Bahia, e em cada uma delas foi aplicado um questionário epidemiológico. Adicionalmente, quando se observavam casos de malformações, os animais eram avaliados vivos ou mortos. Foram necropsiados oito animais (1, 2, 3, 4, 5, 6, 7 e 8), e dois (7 e 8) foram submetidos a exame radiográfico. Sobre a alimentação do rebanho, 40 (97,56%) produtores rurais relataram o livre acesso de seus animais à vegetação nativa. Em relação à presença de Mimosa tenuiflora, 5 (12,2%) informaram que os animais tinham acesso à planta, 15 (36,6 %) disseram que tinham pouco contato, enquanto que 21 (51,2 %) relataram que não havia nenhum contato com a planta, pois essa espécie não estava presente em número relevante na região. Vinte e cinco dos 41 proprietários (60,98%) relataram o consumo de Poincianella pyramidalis. Foi constatado ainda que na maioria das propriedades havia muitas áreas invadidas por P. pyramidalis (80-90% da vegetação). As principais anormalidades relatadas pelos entrevistados em 36 propriedades foram artrogripose (87,80%), agnatia [22 (53,66%)], desvio lateral da mandíbula [11 (26,82%)], escoliose [6 (14,63%)], micrognatia [6 (14,63%)], fenda palatina [4 (9,75%)], crânio aumentado de tamanho [4 (9,75%)], microftalmia [2 (4,88%)], braquignatismo [1 (2,43%)], exoftalmia [1 (2,43%)] e deformidades múltiplas no crânio [1 (2,43%)]. No exame clínico de 13 animais com malformações, as principais alterações foram artrogripose bilateral dos membros torácicos (6/13); queilosquise (2/13); micrognatia (1/13) e má oclusão dentária (1/13). Considerando que algumas dessas malformações foram reproduzidas experimentalmente em caprinos pode-se sugerir P. pyramidalis como mais uma planta teratogênica para ruminantes no Nordeste do Brasil.(AU)

The aim of this paper is to describe the epidemiological, clinical-pathological and radiological aspects of malformations in small ruminants in the semi-arid state of Bahia. Technical visits were carried out in 41 rural properties in the city of Uauá, Bahia, and in each of them, an epidemiological questionnaire was applied. In addition, when malformations were observed, the animals were evaluated alive or dead. Eight animals (1, 2, 3, 4, 5, 6, 7 and 8) were necropsied, and two (7 and 8) were submitted to radiographic examination. Regarding the feeding of the herd, 40 (97.56%) farmers reported the free access of their animals to the native vegetation. Regarding the presence of Mimosa tenuiflora, 5 (12.2%) said that the animals had access to the plant, 15 (36.6%) was informed they had little contact, while 21 (51.2%) reported that there was no contact with the plant, because this species were not present in a relevant number in the region. Twenty five out of 41 owners (60.98%) reported the consumption of Poincianella pyramidalis. It was also verified that in the majority of the properties there were many areas invaded by P. pyramidalis (80-90% of the vegetation). The main abnormalities reported by the interviewees on 36 properties were arthrogryposis (87.80%), agnatia [22 (53.66%)], lateral deviation of the mandible [11 (26.82%)], scoliosis [6 (14.63%)], micrognathia [6 (14.63%)], cleft palate [4 (9.75%)], skull enlarged in size [4 (9.75%)], microphthalmia [2 (4.88%)], braquignatism [1 (2.43%)], exophthalmia [1 (2.43%)] and, multiple deformities in the skull [1 (2.43%)]. In the clinical examination of 13 animals with malformations, the main alterations were bilateral arthrogryposis of the thoracic limbs (6/13); cleft lip (2/13); micrognathia (1/13) and dental malocclusion (1/13). Considering that some of these malformations were reproduced experimentally in goats, it is possible to suggest P. pyramidalis as another teratogenic plant for ruminants in Northeast Brazil.(AU)

Effects of Immediate Dentin Sealing and Pulpal Pressure on Resin Cement Bond Strength and Nanoleakage.

OBJECTIVE: The object of this study was to evaluate the simulated pulpal pressure (SPP) and immediate dentin sealing technique (IDS) effects on the microtensile bond strength (µTBS) and nanoleakage of interfaces produced by different luting agents. METHODS AND MATERIALS: Two self-adhesive luting agents (RelyX Unicem [UC] and Clearfil SA Luting [SA]) and two conventional luting agents (Rely X ARC [RX] and Panavia F [PF]) were evaluated. Eighty human molars were divided in four groups according to luting agents. Each group was subdivided according to SPP (with or without) and dentin sealing (immediate or delayed) using Clearfil SE Bond (n=5). After IDS was performed, specimens were stored in water for seven days before luting procedures. Composite blocks were luted according to the manufacturers' instructions. One half of the specimens were subjected to 15 cm H2O of hydrostatic pressure for 24 hours before cementation procedures and continued for 24 hours afterward. Then, restored teeth were sectioned into beams and tested in tension. Two additional teeth per group were prepared for nanoleakage evaluation with scanning electron microscopy. Bond strength data were statistically analyzed by three-way analysis of variance and Tukey test. RESULTS: µTBS of RX decreased when it was subjected to SPP without IDS. However, in the same conditions, µTBS of UC increased. The IDS prevented negative influence of SPP on µTBS of RX and PF; however, a decrease in µTBS of SA and UC was observed. Except for RX, IDS increased µTBS for all resin cements. CONCLUSION: Independent of SPP, the IDS technique obtained higher µTBS for PF, SA, and UC and did not influence RX µTBS.

Effect of long-term simulated pulpal pressure on the bond strength and nanoleakage of resin-luting agents with different bonding strategies.

This study evaluated the effects of simulated hydrostatic pulpal pressure (SPP) on the microtensile bond strength (µTBS) to dentin and nanoleakage patterns produced by self-adhesive luting agents after 12 months. Three self-adhesive luting agents (RelyX Unicem [UN], RelyX U100 [UC], and Clearfil SA Luting [SA]) and three conventional luting agents (Rely X ARC [RX], Panavia F [PF], and a two-step self-etching adhesive system [Clearfil SE Bond] associated with Panavia F [PS]) were evaluated. One hundred twenty-three human molars were abraded to expose occlusal surfaces. Resin cements were used to lute cylindrical composite blocks to the teeth either subjected or not to SPP. Sixty specimens were subjected to 15 cm H2O of SPP for 24 hours before and 24 hours or 12 months after cementation procedures. Afterward, restored teeth were serially sectioned into beams with a cross-sectional area of 1 mm(2) at the bonded interface and were tested in tension (cross-head speed of 1 mm/min). Failure mode was determined using scanning electron microscopy (SEM). Data were statistically analyzed by three-way analysis of variance and post hoc Tukey test (p=0.05). Two additional teeth in each group were serially sectioned into 0.9-mm-thick slabs, which were submitted to a nanoleakage protocol with AgNO3 and analyzed with scanning and transmission electron microscopes. The µTBS values of the etch-and-rinse group (RX) were negatively influenced by SPP and long-term water storage with SPP. After 12 months, UC and SA presented premature failures in all specimens when submitted to SPP. SPP increased silver deposition in most groups in both evaluation times. The hydrostatic pulpal pressure effect was material dependent. The storage time without SPP did not affect bond strength. However, long-term SPP influenced the performance of the etch-and-rinse and self-adhesive cements regarding µTBS and nanoleakage pattern, except to UN.

Effect of sodium ascorbate on dentin bonding after two bleaching techniques.

The purpose of this study was to analyze the influence of 10% sodium ascorbate (SA) on the hybrid layer, resin tag length, and bond strength to dentin after bleaching. Six groups were tested: G C, control; G SA, sodium ascorbate (SA) + restoration; G CP, bleaching with carbamide peroxide (CP) + restoration; G CP+SA, bleaching with CP + SA+ restoration; G HP, bleaching with 35% hydrogen peroxide (HP) + restoration; and G HP+SA, HP + SA + restoration. After dental bleaching, the dentin was exposed and the antioxidant solution was applied to groups G SA, G CP+SA, and G HP+SA, before bonding procedures. The teeth were sectioned in the mesiodistal direction. One section was decalcified, and the specimens were embedded in paraffin and sectioned in the longitudinal direction with a thickness of 6 µm. Fifteen slices of each specimen were selected according to a systematic sample of slices with an interval proportional to the total number of slices obtained for each tooth. The specimens were stained using the Brown & Brenn method, and an optic microscope was used to analyze the hybrid layer thickness and resin tag length. The remaining tooth segment was sectioned into stick-shaped specimens and used for microtensile bond strength testing (0.5 mm/min). Statistical analysis was performed using two-way analysis of variance and Fisher test. The results for hybrid layer + tag formation (in micrometers) were G C, 13.27 Aa; G SA, 11.85 Ba; G CP, 6.84 Bb; G CP+SA, 9.02 Ab; G HP, 7.28 Bb; and G HP+SA, 9.22 Ab; bond strength results (in MPa) were G C, 49.5 Aa; G SA, 51.7 Aa; G CP, 37.16 Bb; G CP+SA, 47.69 Aa; G HP, 32.39 Ab; and G HP+SA, 39.67 Ab. Tooth bleaching with CP or HP impairs the formation of the hybrid layer and resin tags and reduces the microtensile bond strength. Statistically, the use of SA significantly increases the hybrid layer thickness and resin tag length. The microtensile bond strength values for carbamide peroxide increased, but the microtensile bond strength for hydrogen peroxide was not affected.

Accomplishing esthetics using enamel microabrasion and bleaching-a case report.

This case report describes the sequential steps that were used to treat unesthetic, white, hard-texture enamel stains of unknown etiology. A tapered fine diamond bur was used to remove superficial enamel followed by the use of an enamel microabrasion compound Opalustre (Ultradent Products Inc). This technique removed the stains and was followed by polishing with a fluoride paste to restore the enamel to a smooth finish. The teeth were subsequently bleached with carbamide peroxide (Opalescence 10%, Ultradent Products), which achieved the patient's desired esthetic results.

One-year clinical evaluation of composite restorations in posterior teeth: effect of adhesive systems.

This clinical study assessed the performance of posterior composite resins applied with the Adper™ Single Bond Plus (SB) and Adper™ Scotchbond SE (SE) adhesive systems and Filtek™ Supreme Plus composite resin, using modified US Public Health Service criteria. A total of 97 restorations were placed in posterior teeth by two calibrated operators. Application of the materials followed manufacturers' instructions. The restorations were evaluated by two examiners at baseline and after one year. Statistical analyses were conducted using the proportion test at a significance level of 5% (p<0.05). All the restorations evaluated (ie, 100%) received an alpha rating for the criteria of marginal discoloration and marginal integrity at baseline. At one year, for marginal discoloration, 64.6% of SB and 61.2% of SE received an alpha rating. For marginal integrity, 72.9% of SB and 77.6% of SE received an alpha rating. The other restorations received bravo ratings for both criteria. None of the teeth that received the restorative systems presented caries lesions around the restorations. A total of eight teeth presented postoperative sensitivity one week after baseline, five with SB and three with SE; the symptom had disappeared one year later. One year later, composite resin restorations using either adhesive system showed satisfactory clinical performance.

Evaluation of physical properties of enamel after microabrasion, polishing, and storage in artificial saliva.

This study evaluated the effect of microabrasion and polishing on the microhardness and roughness of bovine enamel, and the effect of artificial saliva on the hardness of enamel. Bovine enamel blocks were used, forming the groups (n = 48): GI-37% phosphoric acid and pumice, GII--Opalustre, and GIII--Whiteness RM. The groups were divided into different subgroups: (a) diamond paste, (b) fluoride prophylactic paste, and (c) without polishing. Hardness tests were carried out at the following set times: (T1) initial, (T2) after microabrasion and polishing, (T3) after immersion in artificial saliva for 24 h; and (T4) after seven days of immersion. Surface roughness tests were performed. The obtained data were analyzed by two-factor ANOVA and Tukey's test with significance of 5%. Microhardness increased in T2; without polishing, only groups GII and GIII showed an increased microhardness. T3 did not differ from T4; GI, GII and GIII did not provide surface roughness that differed from each other; and all microabrasive systems followed by polishing showed a higher surface smoothness compared with the control groups. It is concluded that microabrasion followed by polishing provided higher hardness and better surface smoothness of the enamel. However, immersion in artificial saliva was not able to increase the enamel hardness.

Observation of tags and hybrid layer of a single bottle conventional adhesive system and a self-etching adhesive system, on sound dentin.

This experimental light microscopy study investigated the formation of a hybrid layer and resin tags on sound dentin, after utilization of conventional and self-etching adhesive systems. After restorative procedures, the specimens were decalcified in a formic acid and sodium citrate solution, embedded in paraffin, sectioned at 6-microm thickness and stained by the Brown & Brenn method for analysis and measurement by light microscopy (AXIOPHOT) (400x). The results were statistically analyzed by analysis of variance, at a significance level of 5%. Based on the results, it could be concluded that the conventional adhesive allowed the formation of a thicker hybrid layer than the self-etching adhesive, with similar penetration into the dentinal tubules (resin tags).

Observation of tags and hybrid layer of a single bottle conventional adhesive system and a self-etching adhesive system, on sound dentin / Avaliações em microscopia óptica comum da camada hibrida de adesão e dos prolongamentos resinosos (tags) em tecido dentinário hígido: efeitos de um sistema adesivo resinoso frasco único e de um autocondicionante

This experimental light microscopy study investigated the formation of a hybrid layer and resin tags on sound dentin, after utilization of conventional and self-etching adhesive systems. Afterrestorative procedures, the specimens were decalcified in a formic acid and sodium citrate solution, embedded in paraffin, sectioned at 6-ìm thickness and stained by the Brown & Brenn method for analysis and measurement by light microscopy (AXIOPHOT) (400x). The results were statistically analyzed by analysis of variance, at a significance level of 5%. Based on the results, it could be concluded that the conventional adhesive allowed the formation of a thicker hybrid layer than the self-etching adhesive, with similar penetration into the dentinal tubules (resin tags).

Analisamos nesta pesquisa laboratorial/microscópica, o poder deformação da camada híbrida de adesão e dos prolongamentos resinosos (tags) em tecido dentinário hígido, empregando, para tanto, nesse substrato dental, um sistema adesivo convencional e outro autocondicionante. Após a realização dos procedimentosrestauradores; os espécimes foram descalcificados em solução de ácido fórmico/citrato de sódio, incluídos em parafina, cortados a uma espessura de 6 micrometros, corados pelo método Brown & Brenn, para posteriormente, serem analisados e mensurados emmicroscopia óptica comum (AXIOPHOT) (400X). Após a coleta dos resultados, estes foram submetidos à análise estatística ANOVA, ao nível de 5%. De acordo com os resultados obtidospudemos concluir que o adesivo convencional possibilitou a formaçãode uma camada híbrida de adesão mais espessa do que o adesivo autocondicionante e um mesmo nível penetração no interior do túbulo dentinário (Tags).

Observation of tags and hybrid layer of a single bottle conventional adhesive system and a self-etching adhesive system, on sound dentin / Avaliaþ§es em microscopia óptica comum da camada hibrida de adesÒo e dos prolongamentos resinosos (tags) em tecido dentinário hígido: efeitos de um sistema adesivo resinoso frasco único e de um autocondicionante

This experimental light microscopy study investigated the formation of a hybrid layer and resin tags on sound dentin, after utilization of conventional and self-etching adhesive systems. Afterrestorative procedures, the specimens were decalcified in a formic acid and sodium citrate solution, embedded in paraffin, sectioned at 6-ým thickness and stained by the Brown & Brenn method for analysis and measurement by light microscopy (AXIOPHOT) (400x). The results were statistically analyzed by analysis of variance, at a significance level of 5%. Based on the results, it could be concluded that the conventional adhesive allowed the formation of a thicker hybrid layer than the self-etching adhesive, with similar penetration into the dentinal tubules (resin tags).(AU)

Analisamos nesta pesquisa laboratorial/microscópica, o poder deformaþÒo da camada híbrida de adesÒo e dos prolongamentos resinosos (tags) em tecido dentinário hígido, empregando, para tanto, nesse substrato dental, um sistema adesivo convencional e outro autocondicionante. Após a realizaþÒo dos procedimentosrestauradores; os espécimes foram descalcificados em soluþÒo de ácido fórmico/citrato de sódio, incluídos em parafina, cortados a uma espessura de 6 micrometros, corados pelo método Brown & Brenn, para posteriormente, serem analisados e mensurados emmicroscopia óptica comum (AXIOPHOT) (400X). Após a coleta dos resultados, estes foram submetidos O análise estatística ANOVA, ao nível de 5%. De acordo com os resultados obtidospudemos concluir que o adesivo convencional possibilitou a formaþÒode uma camada híbrida de adesÒo mais espessa do que o adesivo autocondicionante e um mesmo nível penetraþÒo no interior do túbulo dentinário (Tags).(AU)

A new biomechanical hand prosthesis controlled by surface electromyographic signals.

This paper describes the development of a low-cost hand prosthesis for use in patients with an amputated hand due to congenital problems or to trauma wound, who possess a part or the forearm endowed with muscular activity. The paper covers the constructive aspects of both mechanical and electronic designs. The prototype is controlled by electromyographic signals measured at the remaining part of the injured limb of the patient. The EMG signals are measured at the surface of the skin, at a point that is close to a working muscle of the amputated arm. The prosthesis allows the patient to hold objects by means of a three finger clamp. The prosthesis presented an excellent performance in preliminary tests with an amputated patient. These tests showed that the prosthesis had a very good performance regarding force and speed.

Tunable vertical-cavity surface-emitting laser with feedback to implement a pulsed neural model. 2. High-frequency effects and optical coupling.

The operation of an optoelectronic dynamic neural model implementation is extended to higher frequencies. A simplified model of thermal effects in vertical-cavity surface-emitting lasers correctly predicts the qualitative changes in the nonlinear mapping implementation with frequency. Experiments and simulations show the expected resonance properties of this model neuron, along with the possibility of other dynamic effects in addition to the ones observed in the original FitzHugh-Nagumo equations. Results of optical coupling between two similar pulsing artificial neurons are also presented.

Tunable vertical-cavity surface-emitting laser with feedback to implement a pulsed neural model. 1. Principles and experimental demonstration.

An optoelectronic implementation of a modified FitzHugh-Nagumo neuron model is proposed, analyzed, and experimentally demonstrated. The setup uses linear optics and linear electronics for implementing an optical wavelength-domain nonlinearity. The system attains instability through a bifurcation mechanism present in a class of neuron models, a fact that is shown analytically. The implementation exhibits basic features of neural dynamics including threshold, production of short pulses (or spikes), and refractoriness.