Diet of crab-eating fox (Cerdocyon thous) in two conservation units of the Amazon rainforest, Brazil / Dieta do cachorro-do-mato (Cerdocyon thous) em duas unidades de conservação da Floresta Amazônica, Brasil

Abstract The present study aimed to evaluate the diet of the free-living crab-eating fox by identifying the stomach contents of the 17 crab-eating foxes (Cerdocyon thous) roadkilled in two conservation units, both located in the Amazon rainforest. The food items were quantified by frequency of occurrence (FO) and percentage of occurrence (PO). The stomach contents were analysed for dry matter (DM), crude protein (CP), crude fibre (CF), ether extract (EE), and mineral matter (MM). Nitrogen-free extractives (NFE), metabolisable energy (ME) values, as well as the energy need for maintenance were estimated. The composition of the diet for the crab-eating fox presented 29 food items from the different taxonomic groups, with a greater diversity of items of animal origin (n=22), although the highest frequency of occurrence was gramineae (Poaceae) (41.18%). Among the items of animal origin, 21% were mammals, 18% reptiles, 10% amphibians, 9% invertebrates and 3% birds. A high content of CF (62.76%) were determined. Nitrogen-free extractive and dry matter averages were 5.91% and 141.82 kcal/100g, respectively. The average maintenance energy was 447.01 kcal/day. These findings suggesting that the crab-eating foxes have a generalist diet with an omnivorous diet in the Amazon basin, feeding on gramineae, fruits, insects, snakes, amphibians, birds and small mammals and have the same feeding habit that present in other Brazilian biomes.

Resumo Este estudo objetivou analisar a dieta do cachorro-do-mato, de vida livre, por meio da identificação do conteúdo estomacal de 17 Cerdocyon thous atropelados em duas unidades de conservação da Floresta Amazônica. O conteúdo estomacal foi analisado e os itens alimentares foram quantificados pela frequência de ocorrência (FO) e percentagem de ocorrência (PO). Também foram avaliados os teores de matéria seca (MS), proteína bruta (PB), fibra bruta (FB), extrato etéreo (EE) e, matéria mineral (MM). Foram estimados o extrativo não-nitrogenado (ENN), a energia metabolizável (EM) e a necessidade energética de manutenção. A composição da dieta do cachorro-do-mato apresentou 29 itens alimentares dos diferentes grupos taxonômicos, tendo uma maior diversidade de itens de origem animal (n=22), ainda que a maior FO tenha sido de gramíneas (Poaceae) (41.18%). Dentre os itens de origem animal, 21% eram mamíferos, 18% répteis, 10% anfíbios, 9% invertebrados e 3% aves. Determinou-se um alto teor de FB (62.76%). A média do ENN e da MS foi 5.91% e 141.82 kcal/100g, respectivamente. A média da energia de manutenção foi 447.01 kcal/dia. Estes achados sugerem que o cachorro-do-mato encontrado na Bacia Amazônica é um animal generalista com uma dieta onívora, se alimentando de gramíneas, frutos, insetos, serpentes, anfíbios, aves e pequenos mamíferos, portanto com o mesmo hábito alimentar relatado a esta espécie quando encontrada em outros biomas brasileiros.

Diet of crab-eating fox (Cerdocyon thous) in two conservation units of the Amazon rainforest, Brazil

Abstract The present study aimed to evaluate the diet of the free-living crab-eating fox by identifying the stomach contents of the 17 crab-eating foxes (Cerdocyon thous) roadkilled in two conservation units, both located in the Amazon rainforest. The food items were quantified by frequency of occurrence (FO) and percentage of occurrence (PO). The stomach contents were analysed for dry matter (DM), crude protein (CP), crude fibre (CF), ether extract (EE), and mineral matter (MM). Nitrogen-free extractives (NFE), metabolisable energy (ME) values, as well as the energy need for maintenance were estimated. The composition of the diet for the crab-eating fox presented 29 food items from the different taxonomic groups, with a greater diversity of items of animal origin (n=22), although the highest frequency of occurrence was gramineae (Poaceae) (41.18%). Among the items of animal origin, 21% were mammals, 18% reptiles, 10% amphibians, 9% invertebrates and 3% birds. A high content of CF (62.76%) were determined. Nitrogen-free extractive and dry matter averages were 5.91% and 141.82 kcal/100g, respectively. The average maintenance energy was 447.01 kcal/day. These findings suggesting that the crab-eating foxes have a generalist diet with an omnivorous diet in the Amazon basin, feeding on gramineae, fruits, insects, snakes, amphibians, birds and small mammals and have the same feeding habit that present in other Brazilian biomes.

Resumo Este estudo objetivou analisar a dieta do cachorro-do-mato, de vida livre, por meio da identificação do conteúdo estomacal de 17 Cerdocyon thous atropelados em duas unidades de conservação da Floresta Amazônica. O conteúdo estomacal foi analisado e os itens alimentares foram quantificados pela frequência de ocorrência (FO) e percentagem de ocorrência (PO). Também foram avaliados os teores de matéria seca (MS), proteína bruta (PB), fibra bruta (FB), extrato etéreo (EE) e, matéria mineral (MM). Foram estimados o extrativo não-nitrogenado (ENN), a energia metabolizável (EM) e a necessidade energética de manutenção. A composição da dieta do cachorro-do-mato apresentou 29 itens alimentares dos diferentes grupos taxonômicos, tendo uma maior diversidade de itens de origem animal (n=22), ainda que a maior FO tenha sido de gramíneas (Poaceae) (41.18%). Dentre os itens de origem animal, 21% eram mamíferos, 18% répteis, 10% anfíbios, 9% invertebrados e 3% aves. Determinou-se um alto teor de FB (62.76%). A média do ENN e da MS foi 5.91% e 141.82 kcal/100g, respectivamente. A média da energia de manutenção foi 447.01 kcal/dia. Estes achados sugerem que o cachorro-do-mato encontrado na Bacia Amazônica é um animal generalista com uma dieta onívora, se alimentando de gramíneas, frutos, insetos, serpentes, anfíbios, aves e pequenos mamíferos, portanto com o mesmo hábito alimentar relatado a esta espécie quando encontrada em outros biomas brasileiros.

Oswaldocruzia franciscoensis n. sp. (Nematoda: Molineidae) in Leptodactylus macrosternum Miranda-Ribeiro, 1926 (Anura: Leptodactylidae) from Caatinga morphoclimatic domain, Brazil: morphological and molecular characterisation.

A new species of Oswaldocruzia Travassos, 1917 (Nematoda, Molineidae), parasite of Leptodactylus macrosternum Miranda-Ribeiro, 1926 (Anura: Leptodactylidae), from Caatinga morphoclimatic domain, Brazil, is described based on morphological and molecular data. Oswaldocruzia franciscoensis n. sp. is characterised by an anterior extremity with a cephalic vesicle divided into two portions, a body covered by cuticular longitudinal ridges, and cervical alae. Males of the new species have caudal bursa of type I with a 2-1-2 pattern, spicules divided into a shoe, bifurcated fork, and blade with two unequal branches, in which the longer branch bifurcates at its distal portion end and the smaller branch with three distal processes, each with distal bifurcations. Females have didelphic and amphidelphic uteri, an ovijector divided into vestibule, anterior and posterior sphincters, and anterior and posterior infundibula. The new species differs from its Neotropical congeners that have caudal bursa of type I, based on the presence of cervical alae and by having a spicular blade distally divided into two unequal branches, with the longer branch bifurcating at its distal portion and smaller branch with three distal processes, each distally bifurcated. The partial 18S rDNA sequence generated for Oswaldocruzia franciscoensis n. sp. is the first of a representative belonging to this genus in the Neotropical region.

Diet of crab-eating fox (Cerdocyon thous) in two conservation units of the Amazon rainforest, Brazil.

The present study aimed to evaluate the diet of the free-living crab-eating fox by identifying the stomach contents of the 17 crab-eating foxes (Cerdocyon thous) roadkilled in two conservation units, both located in the Amazon rainforest. The food items were quantified by frequency of occurrence (FO) and percentage of occurrence (PO). The stomach contents were analysed for dry matter (DM), crude protein (CP), crude fibre (CF), ether extract (EE), and mineral matter (MM). Nitrogen-free extractives (NFE), metabolisable energy (ME) values, as well as the energy need for maintenance were estimated. The composition of the diet for the crab-eating fox presented 29 food items from the different taxonomic groups, with a greater diversity of items of animal origin (n=22), although the highest frequency of occurrence was gramineae (Poaceae) (41.18%). Among the items of animal origin, 21% were mammals, 18% reptiles, 10% amphibians, 9% invertebrates and 3% birds. A high content of CF (62.76%) were determined. Nitrogen-free extractive and dry matter averages were 5.91% and 141.82 kcal/100g, respectively. The average maintenance energy was 447.01 kcal/day. These findings suggesting that the crab-eating foxes have a generalist diet with an omnivorous diet in the Amazon basin, feeding on gramineae, fruits, insects, snakes, amphibians, birds and small mammals and have the same feeding habit that present in other Brazilian biomes.

Diurnal behaviors and herd characteristics of dairy cows housed in a compost-bedded pack barn system under hot and humid conditions.

With international demand for production systems aimed at thermal comfort and animal welfare, milk producers have become increasingly interested in compost barns. However, doubts about the behavioral aspects of cows in tropical and subtropical climates remain, because the compost barn system offers a larger bed area per animal at a lower stocking rate. The objective of this study was to evaluate whether the diurnal behaviors, hygiene and lameness of crossbred dairy cows are influenced by different number of lactations when housed in a compost-bedded pack barn system under hot and humid conditions. Crossbred cows (Holstein and Jersey), which were divided into two treatments based on number of lactations (primiparous and multiparous cows), were evaluated during lactation (n=12). The study was conducted from September 2015 to February 2016 in a compost barn in the southwest region of the state of Paraná, Brazil. Daytime behavior was observed between milking schedules using focal observations with 0/1 sampling. Cow hygiene and lameness were evaluated using subjective scores ranging from 1 to 4 and 1 to 5, respectively. Animal behavior and welfare was analyzed using Bayesian inference with a mixed effects model. The probabilities of dyspnea and pushing behaviors were higher (P<0.05) in multiparous cows, and the probability increased during the hottest hours of the day. For both multiparous and primiparous cows, the agonistic behaviors of pushing, butting and chasing peaked during the afternoon. Eating behaviors had the highest likelihood values (0.8 at 0800 h). The cows preferred to remain lying down in the morning, while rest and standing rumination were preferred in the afternoon. Primiparous cows were cleaner than multiparous cows, and the hygiene score for this group was significantly lower (P<0.05). The hygiene and lameness scores for all animals were low, and the highest scores were 1 and 2. In conclusion, multiparous cows exhibited more frequent agonistic behaviors during the hottest hours of the day. Regarding hygiene and lameness scores, multiparous cows exhibited a higher degree of dirtiness compared with the primiparous cows.

Helminth Parasites of the Lizard Nothobachia ablephara (Gymnophthalmidae) in Caatinga Areas from the Sertão of Brazil.

The lizard Nothobachia ablephara is endemic to dune areas and sandy soils adjacent to the São Francisco River in semiarid northeastern Brazil. Forty-nine lizard specimens were collected in 2 Caatinga areas in the municipality of Petrolina in Pernambuco state. Three gastrointestinal helminth taxa were identified, the nematodes Parapharyngodon alvarengai and Physaloptera sp. and the cestode Oochoristica sp. Nothobachia ablephara showed low parasite richness, but high levels of infection by P. alvarengai. There were no significant differences between the parasitism rates of the 2 study areas or between male and female lizards. This is the first study on parasitism in N. ablephara, thereby increasing knowledge of parasite fauna that infect gymnophthalmid lizards in the Sertão of Brazil.

Influência das condições térmicas do galpão de espera climatizado na mortalidade pré-abate de frangos de corte / The influence of thermal conditions from an environmentally controlled preslaughter lairage on mortality of broiler chickens

Avaliou-se o efeito das condições ambientais da espera pré-abate na mortalidade de frangos de corte, mantidos em galpão climatizado em um abatedouro comercial. Foram avaliados 215 caminhões de transporte de um abatedouro comercial quanto ao número de aves mortas durante as operações pré-abate e à temperatura retal dos animais em condição de espera no abatedouro. Os dados foram obtidos no galpão de espera climatizado por meio de ventiladores e nebulizadores, em diferentes períodos: manhã, tarde e noite. As variáveis térmicas, distância, tempo de espera e densidade de aves por caixa foram consideradas na análise. Destacaram-se os efeitos da temperatura, da umidade relativa e do tempo de espera na variação tanto do número de aves mortas por caminhão quanto da temperatura retal dos animais. Com relação à interação entre temperatura e umidade relativa interna do galpão de espera, houve eficiência do ambiente climatizado no abatedouro quanto à diminuição do número de aves mortas. A climatização foi mais expressiva na redução do número de aves mortas e da temperatura retal quando a temperatura do galpão de espera estava entre 21 e 24°C, principalmente em condições de umidade relativa interna em torno de 70%. Nessas condições climatizadas, o tempo de espera acima de duas horas proporcionou maior conforto às aves.

The effect of environment conditions of preslaughter lairage on broiler mortality was assessed in the present study. Daily preslaughter data from 215 broiler flocks were recorded regarding the number of dead chickens during preslaughter operations and rectal temperature of broilers submitted to a lairage environment prior to slaughtering. A holding area at a slaughterhouse with environmental control was assessed. The thermal variables, distance between farms and slaughterhouse, lairage time and density of birds per cage was considered in this analysis. The effect of dry-bulb temperature, relative humidity and lairage time on death before arrival and rectal temperature was highlighted in this assessment. Regarding the interaction between temperature and inside relative humidity, a decrease in preslaughter mortality was observed due to exposure to a controlled environment. The environment control promoted an expressive reduction in dead birds and rectal temperature when the temperature inside the holding area was between 21 and 24 °C, mainly with inside relative humidity around 70%. In these environment control conditions lairage above 2 hours was necessary to reduce the thermal stress of birds.

Termorregulação de pintos de um dia submetidos a ambiente térmico simulado de transporte / Thermoregulation of day-old chickens submitted to simulated transport thermal environment

Objetivou-se, por meio deste trabalho, avaliar a termorregulação de pintos de um dia, mantidos em caixas de transporte, sob condição térmica simulada de transporte. Dois experimentos replicados executados em dias diferentes foram conduzidos em câmara climática. Para cada um dos experimentos, foram utilizados 360 pintos de um dia. Esses animais foram submetidos às condições de frio, conforto e calor, durante uma hora em cada tratamento. Os animais foram mantidos em caixas de transporte de pintos de um dia com quatro compartimentos, sendo cada um deles com 10 animais, totalizando 40 animais por caixa. Foram utilizadas três caixas empilhadas, simulando o que ocorre no caminhão de transporte. Para avaliação fisiológica, foram realizadas as seguintes medidas: frequência respiratória, peso, temperaturas superficial e cloacal. No geral, o posicionamento das caixas não alterou profundamente o conforto térmico dos pintos de um dia. Com relação às faixas térmicas, a condição de frio foi a que mais afetou as respostas fisiológicas, com destaque para as temperaturas superficial média e cloacal. No entanto, com o aumento do tempo de exposição, possivelmente o tratamento térmico por calor possa ter mais efeito sobre a termorregulação desses animais.

An experiment was conducted to assess the thermoregulation of day-old chickens, placed in transport boxes, under simulated transport thermal condition. Two replicated trials were done in two different days in a windowless environmentally controlled chamber. For each one, a total of 360 one-day-old broiler chicks were used. These animals were submitted to three thermal conditions (cold, thermoneutral and heat), for 1 h each. The birds were placed in boxes for day-old chick transport, divided in 40 chicks per box, with three boxes stacked vertically, for each treatment (120 chicks per treatment). Body weight, respiratory frequency, mean surface and cloacal temperature were monitored in a sample of 20 animals per box, with measurements were made before and after the treatments. The box placement had a negligible effect on the thermal comfort of birds. The mean surface and cloacal temperature responses were markedly affected by the cold treatment. However, with an increasing exposure time, the heat treatment might possibly have a clear evidence on the thermoregulation of day-old chickens.

Nonoperative management of rectal cancer after chemoradiation opposed to resection after complete clinical response. A comparative study.

INTRODUCTION: Surgery is the standard treatment of rectal cancer after neoadjuvant therapy. Some authors advocate a nonoperative management (NOM) after complete clinical response (cCR) following chemoradiotherapy (CRT). We compare our results with NOM to standard resection in a retrospective analysis. METHODS: Rectal adenocarcinomas submitted to NOM after CRT between September 2002 and December 2013 were compared to surgical patients that had pathological complete response (pCR) during the same period. Endpoints were Overall Survival (OS), Disease Free Survival (DFS), Local Relapse (LR) and Distant Relapse (DR). RESULTS: Forty-two NOM patients compared to 69 pCR patients operated after a median interval of 35 weeks after CRT. NOM tumors were distal (83.3% vs 59.4%, p = 0.011), less obstructive (26.2% vs 54.4%, p = 0.005) and had a lower digital rectal score (p = 0.024). Twelve (28.0%) recurrences in NOM group and eight (11.5%) in the surgical group occurred after a follow-up of 47.7 and 46.7 months respectively. Isolated LR occurred in five (11%) NOM patients and one (1.4%) in the surgical group. Four (80%) LR were surgically salvaged in NOM group. No difference in OS was found (71.6% vs 89.9%, p = 0.316) but there was a higher DFS favoring surgical group (60.9% vs 82.8%, p = 0.011). Distal tumors had worse OS compared to proximal tumors in surgical group (5-year OS of 85.5% vs 96.2%, p = 0.038). CONCLUSION: The NOM achieved OS comparable to surgical treatment and spared patients from surgical morbidity but it resulted in more recurrences. This approach cannot be advocated routinely and controlled trials are warranted.

Preslaughter mortality of broilers in relation to lairage and season in a subtropical climate.

The preslaughter handling and transport of broilers are stressful operations that might affect welfare and meat quality and could increase numbers of deaths before slaughter. However, the influence of thermal factors during transportation and lairage at slaughterhouses is complex in subtropical regions, where increasing temperature and high RH are the major concerns regarding animal survival before slaughter. In this study we assessed the influence of a controlled lairage environment on preslaughter mortality rates of broiler chickens that were transported during different seasons of the year and had varying lairage times in the subtropical climate. Preslaughter data from 13,937 broiler flocks were recorded daily during 2006 in a commercial slaughterhouse in southeastern Brazil. The main factors that influenced daily mortality rate were mean dry bulb temperature and RH, lairage time, daily periods, density of broilers per crate, season of the year, stocking density per lorry, transport time, and distance between farms and slaughterhouse. A holding area at the slaughterhouse with environmental control was assessed. Using a double GLM for mean and dispersion modeling, the seasons were found to have significant effects (P < 0.05) on average mortality rates. The highest incidence was observed in summer (0.42%), followed by spring (0.39%), winter (0.28%), and autumn (0.23%). A decrease of preslaughter mortality of broilers during summer (P < 0.05) was observed when the lairage time was increased, mainly after 1 h of exposure to a controlled environment. Thus, lairage for 3 to 4 h in a controlled lairage environment during the summer and spring is necessary to reduce the thermal load of broiler chickens.

Calculation of MP2 and coupled-cluster molecular properties using the q-integral method.

The main purpose of this paper is to report results of quantum mechanical calculation of the H(2) system using the q-Integral method with correlation corrections to the SCF (Self Consistent Field) wave functions included through the Møller-Plesset second-order perturbation (MP(2)) and Coupled-Cluster (CC) theory. Using the q-Integral method, we evaluated potential energy curves, rovibrational spectroscopy constants, rovibrational spectra, interatomic equilibrium distance and longitudinal static hyper(polarizability). All calculations were carried out through the STO-3G, STO-6G, and double-zeta (DZV) atomic basis set. The q-Integral method was implemented in the source code of the general ab initio quantum chemistry package GAMESS.

Occurrence Angiostrongylus vasorum (Baillet, 1866) (Nematoda, Angiostrongylidae) in Cerdocyon thous Linnaeus, 1766 (Carnivora, Canidae) in Minas Gerais State Brazil

Registrou-se a ocorrência de A. vasorum em C. thous no Estado de Minas Gerais, e estudaram-se aspectos de sua ecologia nessa população de hospedeiros. A partir da necropsia de seis espécimes, observou-se a presença de A. vasorum nos pulmões e átrio direito de C. thous. No total foram coletados 24 espécimes de A. vasorum, com prevalência de 50 por cento, abundância média de 4±4,47, intensidade média de 8±3,00 e razão sexual (machos/fêmeas) de 1:1,19. As infrapopulações de A. vasorum apresentaram padrão de distribuição espacial agregado (ID=5,70 e K=0,355). Este é o primeiro registro de A. vasorum em C. thous no estado, descrito no município de Juiz de Fora

Oncocalyxone A from Auxemma oncocalyx lacks genotoxic activity in phytohemagglutinin-stimulated lymphocytes.

Inadequate doses or prolonged chemotherapy can be cytotoxic or genotoxic to cancer patients, increasing the risk for the development of a second cancer, particularly acute leukemia. The association between therapeutic and genotoxic properties of oncocalyxone A (Onco A), make cytotoxic tests (mitotic index and chromosomal aberrations) fundamental in the accompaniment of the effects of this active compound. Therefore, the aim of the present study was to determine the genotoxic action of Onco A in vitro, during different phases of the cell cycle, utilizing primary cultures of lymphocytes of healthy individuals. The results showed that Onco A is cytotoxic during the cell cycle phases G1, G1/S, and S, however, not in G2. Onco A did not demonstrate a genotoxic effect in any of the cell cycle phases at the concentration studied. It is concluded that during the period of exposure, this active substance inhibits DNA synthesis and consequently cell division. Therefore, the absence of such genotoxicity for Onco A in the tests performed in this study provides important information in regard to the therapeutic use of this agent. Further studies are necessary to better understand the molecular mechanism of action of Onco A.

Oncocalyxone a from auxemma oncocalyx lacks genotoxic activity in phytohemagglutinin-stimulated lymphocytes

Inadequate doses or prolonged chemotherapy can be cytotoxic or genotoxic to cancer patients, increasing the risk for the development of a second cancer, particularly acute leukemia. The association between therapeutic and genotoxic properties of oncocalyxone A (Onco A), make cytotoxic tests (mitotic index and chromosomal aberrations) fundamental in the accompaniment of the effects of this active compound. Therefore, the aim of the present study was to determine the genotoxic action of Onco A in vitro, during different phases of the cell cycle, utilizing primary cultures of lymphocytes of healthy individuals. The resultsshowed that Onco A is cytotoxic during the cell cycle phases G1, G1/S, and S,however, not in G2. Onco A did not demonstrate a genotoxic effect in any of the cell cycle phases at the concentration studied. It is concluded that during the period of exposure, this active substance inhibits DNA synthesis and consequently cell division. Therefore, the absence of such genotoxicity for Onco A in the tests performed in this study provides important information in regard tothe therapeutic use of this agent. Further studies are necessary to betterunderstand the molecular mechanism of action of Onco A.

Oscillations and multiple steady states in active membrane transport models.

The dynamic behavior of some non-linear extensions of the six-state alternating access model for active membrane transport is investigated. We use stoichio-metric network analysis to study the stability of steady states. The bifurcation analysis has been done through standard numerical methods. For the usual six-state model we have proved that there is only one steady state, which is globally asymptotically stable. When we added an autocatalytic step we found self-oscillations. For the competition between a monomer cycle and a dimer cycle, with steps of dimer formation, we have also found self-oscillations. We have also studied models involving the formation of a complex with other molecules. The addition of two steps for formation of a complex of the monomer with another molecule does not alter either the number or the stability of steady states of the basic six-state model. The model which combines the formation of a complex with an autocatalytic step shows both self-oscillations and multiple steady states. The results lead us to conclude that oscillations could be produced by active membrane transport systems if the transport cycle contains a sufficiently large number of steps (six in the present case) and is coupled to at least one autocatalytic reaction,. Oscillations are also predicted when the monomer cycle is coupled to a dimer cycle. In fact, the autocatalytic reaction can be seen as a simplification of the model involving competition between monomer and dimer cycles, which seems to be a more realistic description of biological systems. A self-regulation mechanism of the pumps, related to the multiple stationary states, is expected only for a combined effect of autocatalysis and formation of complexes with other molecules. Within the six-state model this model also leads to oscillation.

Inhibitory sidebands in multiple angular frequency filters in the human visual system.

The view of multiple spatial frequency channels to characterize spatial factors determining the processing of contrast and brightness information has been mostly based on studies using sine wave gratings. In a study of angular frequency filtering, we demonstrated the presence of multiple peaks reflecting inhibitory activity in the measurement of a 24-cycle angular frequency filter (Simas MLB & Dodwell PC (1990). Spatial Vision, 5: 59-74). We now report sensitivity functions for angular frequency filters at 2, 4, 9, 13, 16, and 47 cycles, and have included new data for 24 cycles using the same method and analogous equipment to allow comparisons with our previous study. The present findings consistently show inhibitory effects flanking the filter's specific test frequency and, in every case, much weaker or almost no inhibition occurs at the specific test frequency for the given angular frequency filter.

Inhibitory sidebands in multiple angular frequency filters in the human visual system

The view of multiple spatial frequency channels to characterize spatial factors determining the processing of contrast and brightness information has been mostly based on studies using sinewave gratings. In a study of angular frequency filtering, we demonstrated the presence of multiple peaks reflecting inhibitory activity in the measurement of a 24-cycle angular frequency filter (Simas MLB & Dodwell PC (1990). Spatial Vision, 5:59-74). We now report sensitivity functions for angular frequency filters at 2, 4, 9, 13, 16 and 47 cycles, and have included new data for 24 cycles using the same method and analogous equipement to allow comparison with our previous study. The present findings consistently show inhibitory effects flanking the filter's specific test frequency and, in every case, much weaker or almost no inhibition occurs at the specific test given angular frequency filter