RESUMO
Eco-friendly carbothermal techniques were used to synthesize nanocomposites of biowaste-derived Ni/NiO decorated-2D biochar. The use of chitosan and NiCl2 in the carbothermal reduction technique was a novelty to synthesize the Ni/NiO decorated-2D biochar composite. Potassium persulfate (PS) was found to be activated by Ni/NiO decorated-2D biochar, which is thought to oxidize organic pollutants through an electron pathway designed by the reactive complexes formed between PS and the Ni/NiO biochar surface. This activation led to the efficient oxidation of methyl orange and organic pollutants. Analyzing Ni/NiO decorated-2D biochar composite before and after the methyl orange adsorption and degradation procedure allowed us to report on the process of its elimination. The Ni/NiO biochar with PS activation showed higher efficiency than Ni/NiO decorated-2D biochar composite as this material was able to degrade over 99% of the methyl orange dye. The effects of initial methyl orange concentration, dosages effect, solution pH, equilibrium studies, kinetics, thermodynamic studies, and reusability were examined and evaluated on Ni/NiO biochar.
Assuntos
Poluentes Ambientais , Poluentes Químicos da Água , Adsorção , Compostos Azo/química , Carvão Vegetal/química , Poluentes Químicos da Água/análiseRESUMO
BACKGROUND AND PURPOSE: Limited evidence exists on the benefits of organized care for improving risk factor control in patients with stroke or transient ischaemic attack. The effectiveness of an individualized management programme in reducing absolute cardiovascular disease risk in this high-risk population was determined. METHODS: This was a prospective, multicentre, cluster-randomized controlled trial with blinded assessment of outcomes and intention-to-treat analysis. Patients hospitalized for stroke/transient ischaemic attack and aged ≥18 years were recruited from four hospitals. General practices treating recruited patients were randomized to provide either usual care or an individualized management programme comprising nurse-led education and review of care plans by stroke specialists in addition to usual care. The primary outcome was a change in cardiovascular Framingham Risk Score between baseline and 12 months. RESULTS: From January 2010 to November 2013, 156 general practices (280 patients) were randomly assigned to usual care (control) and 159 (283 patients) to the intervention. The median age was 70.1 years; 65% were male. Overall, >80% of participants were prescribed recommended secondary prevention therapies at baseline. The primary efficacy analysis comprised 533 participants, with 30 either dying or lost to follow-up. In adjusted analyses, no significant between-group difference was found in the cardiovascular risk score at 12 months (0.04, 95% confidence interval -1.7, 1.8). CONCLUSIONS: The effectiveness of an organized secondary prevention programme for stroke may be limited in patients from high-performing hospitals with regular post-discharge follow-up and communication with general practices.
Assuntos
Gerenciamento Clínico , Acidente Vascular Cerebral/terapia , Idoso , Idoso de 80 Anos ou mais , Avaliação da Deficiência , Feminino , Humanos , Ataque Isquêmico Transitório/terapia , Masculino , Pessoa de Meia-Idade , Enfermeiras e Enfermeiros , Equipe de Assistência ao Paciente , Educação de Pacientes como Assunto , Médicos , Medicina de Precisão , Estudos Prospectivos , Fatores de Risco , Acidente Vascular Cerebral/mortalidade , Resultado do TratamentoRESUMO
BACKGROUND: Type 2 Diabetes (T2D) is associated with increased risk of dementia. We aimed to determine the feasibility of a randomised controlled trial (RCT) examining the efficacy of exercise on cognition and brain structure in people with T2D. METHODS: A 6-month pilot parallel RCT of a progressive aerobic- and resistance-training program versus a gentle movement control group in people with T2D aged 50-75 years (n = 50) at the University of Tasmania, Australia. Assessors were blinded to group allocation. Brain volume (total, white matter, hippocampus), cortical thickness and white matter microstructure (fractional anisotrophy and mean diffusivity) were measured using magnetic resonance imaging, and cognition using a battery of neuropsychological tests. Study design was assessed by any changes (during the pilot or recommended) to the protocol, recruitment by numbers screened and time to enrol 50 participants; randomisation by similarity of characteristics in groups at baseline, adherence by exercise class attendance; safety by number and description of adverse events and retention by numbers withdrawn. RESULTS: The mean age of participants was 66.2 (SD 4.9) years and 48% were women. There were no changes to the design during the study. A total of 114 people were screened for eligibility, with 50 participants with T2D enrolled over 8 months. Forty-seven participants (94%) completed the study (23 of 24 controls; 24 of 26 in the intervention group). Baseline characteristics were reasonably balanced between groups. Exercise class attendance was 79% for the intervention and 75% for the control group. There were 6 serious adverse events assessed as not or unlikely to be due to the intervention. Effect sizes for each outcome variable are provided. CONCLUSION: This study supports the feasibility of a large scale RCT to test the benefits of multi-modal exercise to prevent cognitive decline in people with T2D. Design changes to the future trial are provided. TRIAL REGISTRATION: ANZCTR 12614000222640 ; Registered 3/3/2014; First participant enrolled 26/6/2014, study screening commenced 1/9/2014; Australian and New Zealand Clinical Trial Registry.
Assuntos
Demência/terapia , Diabetes Mellitus Tipo 2/fisiopatologia , Terapia por Exercício , Idoso , Encéfalo/diagnóstico por imagem , Encéfalo/fisiopatologia , Transtornos Cognitivos/complicações , Transtornos Cognitivos/diagnóstico por imagem , Transtornos Cognitivos/fisiopatologia , Transtornos Cognitivos/terapia , Demência/complicações , Demência/diagnóstico por imagem , Demência/fisiopatologia , Diabetes Mellitus Tipo 2/complicações , Exercício Físico , Terapia por Exercício/métodos , Estudos de Viabilidade , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Projetos Piloto , Treinamento ResistidoRESUMO
BACKGROUND AND PURPOSE: The differences in gait abnormalities from the earliest to the later stages of dementia and in the different subtypes of dementia have not been fully examined. This study aims to compare spatiotemporal gait parameters in cognitively healthy individuals, patients with amnestic mild cognitive impairment (MCI) and non-amnestic MCI, and patients with mild and moderate stages of Alzheimer's disease (AD) and non-Alzheimer's disease (non-AD). METHODS: Based on a cross-sectional design, 1719 participants (77.4 ± 7.3 years, 53.9% female) were recruited from cohorts from seven countries participating in the Gait, Cognition and Decline (GOOD) initiative. Mean values and coefficients of variation of spatiotemporal gait parameters were measured during normal pace walking with the GAITRite system at all sites. RESULTS: Performance of spatiotemporal gait parameters declined in parallel with the stage of cognitive decline from MCI status to moderate dementia. Gait parameters of patients with non-amnestic MCI were more disturbed compared to patients with amnestic MCI, and MCI subgroups performed better than demented patients. Patients with non-AD dementia had worse gait performance than those with AD dementia. This degradation of gait parameters was similar between mean values and coefficients of variation of spatiotemporal gait parameters in the earliest stages of cognitive decline, but different in the most advanced stages, especially in the non-AD subtypes. CONCLUSIONS: Spatiotemporal gait parameters were more disturbed in the advanced stages of dementia, and more affected in the non-AD dementias than in AD. These findings suggest that quantitative gait parameters could be used as a surrogate marker for improving the diagnosis of dementia.
Assuntos
Doença de Alzheimer/fisiopatologia , Amnésia/fisiopatologia , Disfunção Cognitiva/fisiopatologia , Demência/fisiopatologia , Transtornos Neurológicos da Marcha/fisiopatologia , Idoso , Idoso de 80 Anos ou mais , Doença de Alzheimer/complicações , Amnésia/complicações , Disfunção Cognitiva/complicações , Estudos Transversais , Demência/complicações , Feminino , Transtornos Neurológicos da Marcha/etiologia , Humanos , Masculino , FenótipoRESUMO
BACKGROUND: Successful restoration of structure and function using autologous free fat grafts has remained elusive. Review of literature shows that various harvesting and preparation techniques have been suggested. The goal of these techniques is to obtain greater adipocyte cell survival and consequently more reliable clinical results. MATERIALS AND METHODS: In our technique, a piece of mesh is kept at one end of the lipoaspiration syringe, which is then connected to the Suction pump. As one syringe fills, it is replaced by another one until the required amount of fat is obtained. RESULTS: By using a polypropylene mesh in our technique, we can separate the transfusate from the harvested fat graft during harvesting itself. The fat graft thus obtained is dense and concentrated, with fewer impurities. CONCLUSION: Hence, we recommend our technique as a reliable method for extracting sterile emulsified fat in an economical way.
RESUMO
Transient ischaemic attack (TIA) if untreated carries a high risk of early stroke and is associated with poorer long-term survival. There have been recent advances in the understanding of TIA, its investigations, management and organisation of services for patient care. Clinically, patients are diagnosed TIA if they have transient sudden-onset focal neurological symptoms which usually completely and rapidly resolve by presentation. Patients with residual symptoms should be evaluated as potentially having stroke, if they present within 4.5 h of onset, should be urgently evaluated for their potential eligibility for thrombolysis. TIA patients should receive rapid attention with essential investigations, including brain imaging, electrocardiograph and carotid ultrasound. Immediate administration of an antiplatelet agent is recommended after brain imaging, with subsequent attention to preventing or treating other mechanistic factors. There is emerging evidence that TIA patients can be managed safely in the outpatient setting after initial rapid management in emergency departments as part of a structured clinical pathway supervised by stroke specialists. Clinical systems of management may require approaches individualised to the healthcare setting, while adopting the central aspects of rapid management.
Assuntos
Ataque Isquêmico Transitório/diagnóstico , Ataque Isquêmico Transitório/terapia , Animais , Anti-Hipertensivos/uso terapêutico , Diagnóstico por Imagem/tendências , Gerenciamento Clínico , Eletrocardiografia/tendências , Humanos , Ataque Isquêmico Transitório/epidemiologia , Inibidores da Agregação Plaquetária/uso terapêutico , Comportamento de Redução do Risco , Acidente Vascular Cerebral/diagnóstico , Acidente Vascular Cerebral/epidemiologia , Acidente Vascular Cerebral/prevenção & controleRESUMO
In 358 participants of the Tasmanian Healthy Brain Project, we quantified the cognitive consequences of engaging in varying loads of university-level education in later life, and investigated whether or not BDNF Val66Met affected outcomes. Assessment of neuropsychological, health, and psychosocial function was undertaken at baseline, 12-month, and 24-month follow-up. Education load was positively associated with change in language processing performance, but this effect did not reach statistical significance (P = 0.064). The BDNF Val66Met polymorphism significantly moderated the extent to which education load was associated with improved language processing (P = 0.026), with education load having a significant positive relationship with cognitive change in BDNF Met carriers but not in BDNF Val homozygotes. In older adults who carry BDNF Met, engaging in university-level education improves language processing performance in a load-dependent manner.
Assuntos
Envelhecimento/genética , Fator Neurotrófico Derivado do Encéfalo/genética , Cognição , Polimorfismo Genético/genética , Desempenho Acadêmico , Idoso , Envelhecimento/fisiologia , Estudos de Casos e Controles , Disfunção Cognitiva/prevenção & controle , Humanos , Pessoa de Meia-Idade , Testes Neuropsicológicos , Tasmânia , UniversidadesRESUMO
BACKGROUND/AIMS: Our purpose was to examine whether falls risk is associated with cognitive functions beyond executive function/attention and processing speed. METHODS: Cognitive function was measured in a population-based sample (n = 300) of people aged 60-86 years. The physiological profile assessment was used to estimate the falls risk. RESULTS: After adjusting for confounders, visual construction (p < 0.01), executive function/attention and memory (both p < 0.05) were independently associated with falls risk. The associations for visual construction (p < 0.01) and memory (p < 0.01) remained after adjusting for executive function/ attention. CONCLUSIONS: The neural basis underlying the associations of visuospatial function and memory with falls risk require further study.
Assuntos
Acidentes por Quedas/estatística & dados numéricos , Cognição/fisiologia , Memória/fisiologia , Percepção Espacial/fisiologia , Percepção Visual/fisiologia , Afeto , Idoso , Idoso de 80 Anos ou mais , Atenção/fisiologia , Depressão/psicologia , Feminino , Humanos , Modelos Lineares , Masculino , Pessoa de Meia-Idade , Testes Neuropsicológicos , População , Desempenho Psicomotor/fisiologia , Medição de RiscoRESUMO
INTRODUCTION: The growing burden of chronic diseases means some governments have been providing financial incentives for multidisciplinary care and self-management support delivered within primary care. Currently, population-based evaluations of the effectiveness of these policies are lacking. AIM: To outline the methodological approach for our study that is designed to evaluate the effectiveness (including cost) of primary care policies for chronic diseases in Australia using stroke as a case study. METHODS: Person-level linkages will be undertaken between registrants from the Australian Stroke Clinical Registry (AuSCR) and (i) Government-held Medicare Australia claims data, to identify receipt or not of chronic disease management and care coordination primary care items; (ii) state government-held hospital data, to define outcomes; and (iii) government-held pharmaceutical and aged care claims data, to define covariates. N=1500 randomly selected AuSCR registrants will be sent surveys to obtain patient experience information. In Australia, unique identifiers are unavailable. Therefore, personal-identifiers will be submitted to government data linkage units. Researchers will merge the de-identified datasets for analysis using a project identifier. An economic evaluation will also be undertaken. ANALYSIS: The index event will be the first stroke recorded in the AuSCR. Multivariable competing risks Poisson regression for multiple events, adjusted by a propensity score, will be used to test for differences in the rates of hospital presentations and medication adherence for different care (policy) types. Our estimated sample size of 25,000 patients will provide 80% estimated power (É>0.05) to detect a 6-8% difference in rates. The incremental costs per Quality-adjusted life years gained of community-based care following the acute event will be estimated from a health sector perspective. CONCLUSION: Completion of this study will provide a novel and comprehensive evaluation of the effectiveness and cost-effectiveness of Australian primary care policies. Its success will enable us to highlight the value of data-linkage for this type of research.
RESUMO
The aim of this study was to identify factors associated with awareness, treatment and control of hypertension in a rural setting in India. Following screening of the population, all individuals with hypertension (blood pressure (BP) ⩾140/90 mm Hg or taking antihypertensive medications) were invited to participate in this study. We measured BP, height, weight, skinfolds, waist and hip circumference, and administered a questionnaire to obtain information regarding socioeconomic and behavioural characteristics. Multivariable logistic regression was used to determine factors associated with awareness, treatment and control of hypertension. We recruited 277 individuals with hypertension. Awareness (43%), treatment (33%) and control (27%) of hypertension were poor. Greater distance to health services (odds ratio (OR) 0.56 (95% confidence interval (CI)) 0.32-0.98) was associated with poor awareness of hypertension while having had BP measured within the previous year (OR 4.72, 95% CI 2.71-8.22), older age and greater per cent body fat were associated with better awareness. Factors associated with treatment of hypertension were having had BP measured within the previous year (OR 6.18, 95% CI 3.23-11.82), age ⩾65 years, physical inactivity and greater per cent body fat. The only factor associated with control of hypertension was greater per cent body fat (OR 1.05, 95% CI 1.01-1.11). Improving geographic access and utilisation of health services should improve awareness and treatment of hypertension in this rural population. Further research is necessary to determine drivers of control.
Assuntos
Anti-Hipertensivos/uso terapêutico , Hipertensão , Idoso , Pressão Sanguínea/efeitos dos fármacos , Determinação da Pressão Arterial/métodos , Feminino , Conhecimentos, Atitudes e Prática em Saúde , Acessibilidade aos Serviços de Saúde/estatística & dados numéricos , Humanos , Hipertensão/diagnóstico , Hipertensão/tratamento farmacológico , Hipertensão/epidemiologia , Índia/epidemiologia , Masculino , Pessoa de Meia-Idade , Avaliação das Necessidades , Prevalência , Fatores de Risco , População Rural/estatística & dados numéricos , Fatores SocioeconômicosRESUMO
Many bacteria use rotating helical flagellar filaments to swim. The filaments undergo polymorphic transformations in which the helical pitch and radius change abruptly. These transformations arise in response to mechanical loading, changes in solution temperature and ionic strength, and point substitutions in the amino acid sequence of the protein subunits that make up the filament. To explain polymorphism, we propose a coarse-grained continuum rod theory based on the quaternary structure of the filament. The model has two molecular switches. The first is a double-well potential for the extension of a protofilament, which is one of the 11 almost longitudinal columns of subunits. Curved filament shapes occur in the model when there is a mismatch strain, i.e., when intersubunit bonds in the inner core of the filament prefer a subunit spacing which is intermediate between the two spacings favored by the double-well potential. The second switch is a double-well potential for twist, due to lateral interactions between neighboring protofilaments. Cooperative interactions between neighboring subunits within a protofilament are necessary to ensure the uniqueness of helical ground states. We calculate a phase diagram for filament shapes and the response of a filament to external moment and force.
RESUMO
Exfoliated graphene oxide (EG)/MoO2 composites are synthesized by a simple solid-state graphenothermal reduction method. Graphene oxide (GO) is used as a reducing agent to reduce MoO3 and as a source for EG. The formation of different submicron sized morphologies such as spheres, rods, flowers, etc., of monoclinic MoO2 on EG surfaces is confirmed by complementary characterization techniques. As-synthesized EG/MoO2 composite with a higher weight percentage of EG performed excellently as an anode material in lithium-ion batteries. The galvanostatic cycling studies aided with postcycling cyclic voltammetry and galvanostatic intermittent titrations followed by ex situ structural studies clearly indicate that Li intercalation into MoO2 is transformed into conversion upon aging at low current densities while intercalation mechanism is preferably taking place at higher current rates. The intercalation mechanism is found to be promising for steady-state capacity throughout the cycling because of excess graphene and higher current density even in the operating voltage window of 0.005-3.0 V in which MoO2 undergoes conversion below 0.8 V.
RESUMO
It is uncertain whether small vessel disease underlies the relationship between Type 2 Diabetes Mellitus (T2DM) and brain atrophy. We aimed to study whether retinal vascular architecture, as a proxy for cerebral small vessel disease, may modify or mediate the associations of T2DM with brain volumes. In this cross-sectional study using Magnetic Resonance Imaging (MRI) scans and retinal photographs in 451 people with and without T2DM, we measured brain volumes, geometric measures of retinal vascular architecture, clinical retinopathy, and MRI cerebrovascular lesions. There were 270 people with (mean age 67.3 years) and 181 without T2DM (mean age 72.9 years). T2DM was associated with lower gray matter volume (p = 0.008). T2DM was associated with greater arteriolar diameter (p = 0.03) and optimality ratio (p = 0.04), but these associations were attenuated by adjustments for age and sex. Only optimality ratio was associated with lower gray matter volume (p = 0.03). The inclusion of retinal measures in regression models did not attenuate the association of T2DM with gray matter volume. The association of T2DM with lower gray matter volume was independent of retinal vascular architecture and clinical retinopathy. Retinal vascular measures or retinopathy may not be sufficiently sensitive to confirm a microvascular basis for T2DM-related brain atrophy.
Assuntos
Doenças de Pequenos Vasos Cerebrais/epidemiologia , Cérebro/diagnóstico por imagem , Diabetes Mellitus Tipo 2/epidemiologia , Substância Cinzenta/diagnóstico por imagem , Vasos Retinianos/diagnóstico por imagem , Idoso , Atrofia , Doenças de Pequenos Vasos Cerebrais/diagnóstico por imagem , Doenças de Pequenos Vasos Cerebrais/patologia , Cérebro/patologia , Estudos Transversais , Retinopatia Diabética/epidemiologia , Feminino , Substância Cinzenta/patologia , Humanos , Modelos Lineares , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Tamanho do Órgão , Tasmânia/epidemiologiaRESUMO
BACKGROUND AND PURPOSE: Intracerebral hemorrhage is the most serious complication of thrombolytic therapy for stroke. We explored factors associated with this complication in the Australian Streptokinase Trial. METHODS: The initial CT scans (< or =4 hours after stroke) of 270 patients were reviewed retrospectively by an expert panel for early signs of ischemia and classified into the following 3 categories: no signs or < or =1/3 or >1/3 of the vascular territory. Hemorrhage on late CT scans was categorized as major or minor on the basis of location and mass effect. Stepwise, backward elimination, multivariate logistic regression analysis was used to identify risk factors for each hemorrhage category. RESULTS: Major hemorrhage occurred in 21% of streptokinase (SK) and 4% of placebo patients. Predictors of major hemorrhage were SK treatment (odds ratio [OR], 6.40; 95% CI, 2.50 to 16.36) and elevated systolic blood pressure before therapy (OR, 1.03; 95% CI, 1.01 to 1.05). Baseline systolic blood pressure >165 mm Hg in SK-treated patients resulted in a >25% risk of major secondary hemorrhage. Early ischemic CT changes, either < or =1/3 or >1/3, were not associated with major hemorrhage (OR, 1.58; 95% CI, 0.65 to 3.83; and OR, 1.11; 95% CI, 0.45 to 2.76, respectively). Minor hemorrhage occurred in 30% of the SK and 26% of the placebo group. Predictors of minor hemorrhage were male sex, severe stroke, early CT changes, and SK treatment. Ninety-one percent of patients with major hemorrhage deteriorated clinically compared with 23% with minor hemorrhage. CONCLUSIONS: SK increased the risk of both minor and major hemorrhage. Major hemorrhage was also more likely in patients with elevated baseline systolic blood pressure. However, early CT changes did not predict major hemorrhage. Results from this study highlight the importance of baseline systolic blood pressure as a potential cause of hemorrhage in patients undergoing thrombolysis.
Assuntos
Pressão Sanguínea , Isquemia Encefálica/diagnóstico , Hemorragia Cerebral/induzido quimicamente , Estreptoquinase/efeitos adversos , Acidente Vascular Cerebral/diagnóstico , Doença Aguda , Adulto , Idoso , Idoso de 80 Anos ou mais , Isquemia Encefálica/complicações , Isquemia Encefálica/tratamento farmacológico , Hemorragia Cerebral/diagnóstico por imagem , Feminino , Humanos , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Razão de Chances , Valor Preditivo dos Testes , Ensaios Clínicos Controlados Aleatórios como Assunto , Estudos Retrospectivos , Medição de Risco , Fatores de Risco , Fatores Sexuais , Estreptoquinase/uso terapêutico , Acidente Vascular Cerebral/complicações , Acidente Vascular Cerebral/tratamento farmacológico , Tomografia Computadorizada por Raios X , Resultado do TratamentoRESUMO
Zona pellucida (ZP) glycoproteins have been proposed as candidate antigens for development of immunocontraceptive vaccines. In this study, the efficacy to block fertility by immunization with recombinant bonnet monkey (Macaca radiata) zona pellucida glycoprotein-C (r-bmZPC) expressed in Escherichia coli and its synthetic peptide (P(4): KGDCGTPSHSRRQPHVVSQWSRSA, aa residues 324-347) conjugated to diphtheria toxoid (DT) has been evaluated in a homologous system. Female bonnet monkeys, immunized with P(4)-DT conjugate showed better immunocontraceptive potential as compared to an r-bmZPC-DT immunized group. In spite of high anti-P(4) antibody titres, animals continued to have ovulatory cycles and showed no disturbance in cyclicity (except summer amenorrhoea). No ovarian pathology was observed in the P(4) immunized group. These results suggest that immunization with the P(4) may lead to block in fertility without obvious ovarian dysfunction. However, further inputs are required to identify additional ZP based B-cell epitopes to enhance the contraceptive efficacy.
RESUMO
Hypothyroidism (surgical thyroidectomy) inhibited the activities of acid phosphatase and Mg(2+)-ATPase in seminal vesicular tissue and fluid and that of Ca(2+)- and Na+/K(+)-ATPases in fluid alone, and T4 supplementation restored normalcy in all, except acid phosphatase. Hyperthyroidism (T4 25 micrograms/100g body weight/day for 60 days, im) enhanced the activities of alkaline phosphatase and ATPases in seminal vesicular tissue and fluid, and decreased acid phosphatase activity in tissue alone. Withdrawal of T4 treatment from hyperthyroid rats (after 30 days) augmented the activity of ATPases in tissue and impaired the same in fluid, while phosphomonoesterases remained at hyperthyroid level. The results suggest specific responses of various seminal vesicular phosphatases to altered thyroid hormone status. Modification in the specific threshold of androgen/estrogen action on different phosphatases in seminal vesicles appears to be the plausible mechanism underlying these changes in hypo- and hyperthyroid conditions.
Assuntos
Adenosina Trifosfatases/metabolismo , Hipertireoidismo/enzimologia , Hipotireoidismo/enzimologia , Monoéster Fosfórico Hidrolases/metabolismo , Glândulas Seminais/enzimologia , Albinismo/enzimologia , Animais , ATPase de Ca(2+) e Mg(2+)/metabolismo , ATPases Transportadoras de Cálcio/metabolismo , Masculino , Ratos , Ratos Wistar , ATPase Trocadora de Sódio-Potássio/metabolismoRESUMO
Existing neural network models are capable of tracking linear trajectories of moving visual objects. This paper describes an additional neural mechanism, disfacilitation, that enhances the ability of a visual system to track curved trajectories. The added mechanism combines information about an object's trajectory with information about changes in the object's trajectory, to improve the estimates for the object's next probable location. Computational simulations are presented that show how the neural mechanism can learn to track the speed of objects and how the network operates to predict the trajectories of accelerating and decelerating objects.