RESUMO
The majority of northern peatlands were initiated during the Holocene. Owing to their mass imbalance, they have sequestered huge amounts of carbon in terrestrial ecosystems. Although recent syntheses have filled some knowledge gaps, the extent and remoteness of many peatlands pose challenges to developing reliable regional carbon accumulation estimates from observations. In this work, we employed an individual- and patch-based dynamic global vegetation model (LPJ-GUESS) with peatland and permafrost functionality to quantify long-term carbon accumulation rates in northern peatlands and to assess the effects of historical and projected future climate change on peatland carbon balance. We combined published datasets of peat basal age to form an up-to-date peat inception surface for the pan-Arctic region which we then used to constrain the model. We divided our analysis into two parts, with a focus both on the carbon accumulation changes detected within the observed peatland boundary and at pan-Arctic scale under two contrasting warming scenarios (representative concentration pathway-RCP8.5 and RCP2.6). We found that peatlands continue to act as carbon sinks under both warming scenarios, but their sink capacity will be substantially reduced under the high-warming (RCP8.5) scenario after 2050. Areas where peat production was initially hampered by permafrost and low productivity were found to accumulate more carbon because of the initial warming and moisture-rich environment due to permafrost thaw, higher precipitation and elevated CO2 levels. On the other hand, we project that areas which will experience reduced precipitation rates and those without permafrost will lose more carbon in the near future, particularly peatlands located in the European region and between 45 and 55°N latitude. Overall, we found that rapid global warming could reduce the carbon sink capacity of the northern peatlands in the coming decades.
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Carbono , Pergelissolo , Regiões Árticas , Ciclo do Carbono , EcossistemaRESUMO
BACKGROUND: There is no currently accepted standard in safety evaluation for radial artery intervention. We sought to compare the accuracy of various subjective and objective screening techniques in predicting safety for radial artery intervention. METHODS: Fifty-four patients in a prospective cohort study at a single institution underwent subjective Allen's test, objective Barbeau test, and several objective hand ultrasound techniques to assess safety for radial artery intervention. These results were then compared to the gold standard of conventional hand angiography to document complete palmar arch. Statistical analysis including sensitivity, specificity, positive predictive values, negative predictive values, and accuracy were calculated. RESULTS: Compared to hand angiography, the subjective Allen's test and the objective Princeps Pollicis Artery ultrasound demonstrated the comparable levels of sensitivity (100% vs. 96.7%, respectively), specificity (100% vs. 100%, respectively), and accuracy (97.2% vs. 97.1%, respectively). The objective Barbeau test demonstrated similar results (sensitivity of 100%, accuracy of 98.2%) with the exception of a lower specificity (50%). CONCLUSIONS: There is no currently accepted standard in safety evaluation for radial artery intervention. However, preliminary data suggest that certain subjective and objective techniques such as Allen's testing, Princeps Pollicis artery ultrasound, and Barbeau testing are comparable options in predicting palmar arch patency.
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Angiografia , Cateterismo Periférico , Mãos/irrigação sanguínea , Artéria Radial/diagnóstico por imagem , Ultrassonografia Doppler em Cores , Adulto , Idoso , Idoso de 80 Anos ou mais , Cateterismo Periférico/efeitos adversos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Variações Dependentes do Observador , Valor Preditivo dos Testes , Estudos Prospectivos , Punções , Reprodutibilidade dos Testes , Grau de Desobstrução Vascular , Adulto JovemRESUMO
On St. Paul Island, a remnant of the Bering Land Bridge, woolly mammoths persisted until 5,600 yr BP with no known predators or competitors, providing a natural system for studying hypothesized environmental drivers of extinction. These include overheating due to rising temperatures, starvation, and drought. Here, we test these hypotheses using Niche Mapper and LPJ-GUESS to mechanistically estimate mammoth metabolic rates and dietary and freshwater requirements and, from these, estimate variations in island carrying capacity on St. Paul for the last 17,000 yr. Population carrying capacity may have been several hundred individuals at the time of initial isolation from the mainland. Adult mammoths could have fasted for two to three months, indicating a necessary ability to access snow-buried forage. During the Holocene, vegetation net primary productivity increased, but shrinking island area overrode increased net primary productivity (NPP), lowering carrying capacity to ~100 individuals. NPP and freshwater availability alternated as critical limiting factors for this island population during the environmental changes of the late Pleistocene and Holocene. Only two or three individuals could have been sustained by the freshwater surplus in crater lakes (up to 18 individuals under the most optimistic parameter sensitivity experiments), suggesting that the St. Paul mammoth population was highly dependent on coastal freshwater sources. The simulations are consistent with the available proxy data, while highlighting the need to retrieve new paleohydrological proxy records from the coastal lagoons to test model predictions. More broadly, these findings reinforce the vulnerability of island megaherbivore populations to resource limitation and extinction.
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Mamutes , Animais , Conservação dos Recursos Naturais , Humanos , IlhasRESUMO
Across the Arctic, the net ecosystem carbon (C) balance of tundra ecosystems is highly uncertain due to substantial temporal variability of C fluxes and to landscape heterogeneity. We modeled both carbon dioxide (CO2 ) and methane (CH4 ) fluxes for the dominant land cover types in a ~100-km2 sub-Arctic tundra region in northeast European Russia for the period of 2006-2015 using process-based biogeochemical models. Modeled net annual CO2 fluxes ranged from -300 g C m-2 year-1 [net uptake] in a willow fen to 3 g C m-2 year-1 [net source] in dry lichen tundra. Modeled annual CH4 emissions ranged from -0.2 to 22.3 g C m-2 year-1 at a peat plateau site and a willow fen site, respectively. Interannual variability over the decade was relatively small (20%-25%) in comparison with variability among the land cover types (150%). Using high-resolution land cover classification, the region was a net sink of atmospheric CO2 across most land cover types but a net source of CH4 to the atmosphere due to high emissions from permafrost-free fens. Using a lower resolution for land cover classification resulted in a 20%-65% underestimation of regional CH4 flux relative to high-resolution classification and smaller (10%) overestimation of regional CO2 uptake due to the underestimation of wetland area by 60%. The relative fraction of uplands versus wetlands was key to determining the net regional C balance at this and other Arctic tundra sites because wetlands were hot spots for C cycling in Arctic tundra ecosystems.
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Ciclo do Carbono , Tundra , Regiões Árticas , Carbono , Dióxido de Carbono/análise , Ecossistema , Metano/análise , Federação Russa , Solo , Áreas AlagadasRESUMO
PURPOSE: This study was designed to contribute to the existing research on the coping behaviors, social support, and mental health outcomes in parents of children with epilepsy in the United States. METHODS: Participants included 152, predominantly Caucasian (89.5%), married (78.9%) women (95.4%). Via a web-based interface, mothers completed questionnaires assessing the impact of their child's disability on their family (i.e., severity of their child's disability, family burden, and personal stress), social resources (i.e., perceived social support), coping (i.e., emotion-focused and social support seeking), and adjustment (i.e., depression and anxiety). RESULTS: After controlling for demographic variables, mediational analysis revealed that mothers' perceptions of the severity of their child's disability were associated with decreased perceived social support, which was then related to higher reported levels of depression and anxiety. Similarly, low levels of perceived social support partially mediated the relation between family burden and depression, anxiety, and stress. Finally, mothers' perceptions of the severity of their children's disability and family burden were unrelated to their reports of emotion-focused or social support seeking coping. However, their use of emotion-focused and social support seeking behaviors was related to lower levels of depression. CONCLUSION: Low levels of perceived social support may help to explain the mechanisms underlying the relation between mothers' perceptions of the severity of their child's disability and family burden on their mental health adjustment, such as depression and anxiety.
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Adaptação Psicológica , Efeitos Psicossociais da Doença , Crianças com Deficiência , Epilepsia , Mães/psicologia , Apoio Social , Adulto , Ansiedade/psicologia , Criança , Depressão/psicologia , Feminino , Humanos , Masculino , Saúde Mental , Pessoa de Meia-IdadeRESUMO
Facial appearance can be altered, not just by restyling but also by sensory processes. Exposure to a female face can, for instance, make subsequent faces look more masculine than they would otherwise. Two explanations exist. According to one, exposure to a female face renormalizes face perception, making that female and all other faces look more masculine as a consequence-a unidirectional effect. According to that explanation, exposure to a male face would have the opposite unidirectional effect. Another suggestion is that face gender is subject to contrastive aftereffects. These should make some faces look more masculine than the adaptor and other faces more feminine-a bidirectional effect. Here, we show that face gender aftereffects are bidirectional, as predicted by the latter hypothesis. Images of real faces rated as more and less masculine than adaptors at baseline tended to look even more and less masculine than adaptors post adaptation. This suggests that, rather than mental representations of all faces being recalibrated to better reflect the prevailing statistics of the environment, mental operations exaggerate differences between successive faces, and this can impact facial gender perception.
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Discriminação Psicológica/fisiologia , Reconhecimento Facial/fisiologia , Pós-Efeito de Figura/fisiologia , Adolescente , Adulto , Face , Feminino , Humanos , Masculino , Estimulação Luminosa , Fatores Sexuais , Adulto JovemRESUMO
The Arctic land area has warmed by > 1 °C in the last 30 years and there is evidence that this has led to increased productivity and stature of tundra vegetation and reduced albedo, effecting a positive (amplifying) feedback to climate warming. We applied an individual-based dynamic vegetation model over the Arctic forced by observed climate and atmospheric CO(2) for 1980-2006. Averaged over the study area, the model simulated increases in primary production and leaf area index, and an increasing representation of shrubs and trees in vegetation. The main underlying mechanism was a warming-driven increase in growing season length, enhancing the production of shrubs and trees to the detriment of shaded ground-level vegetation. The simulated vegetation changes were estimated to correspond to a 1.75 % decline in snow-season albedo. Implications for modelling future climate impacts on Arctic ecosystems and for the incorporation of biogeophysical feedback mechanisms in Arctic system models are discussed.
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Mudança Climática , Ecossistema , Modelos Biológicos , Desenvolvimento Vegetal , Regiões Árticas , Simulação por Computador , Estações do Ano , Fatores de TempoRESUMO
Human visual systems have evolved to extract ecologically relevant information from complex scenery. In some cases, the face in the crowd visual search task demonstrates an anger superiority effect, where anger is allocated preferential attention. Across three studies (N = 419), we tested whether facial hair guides attention in visual search and influences the speed of detecting angry and happy facial expressions in large arrays of faces. In Study 1, participants were faster to search through clean-shaven crowds and detect bearded targets than to search through bearded crowds and detect clean-shaven targets. In Study 2, targets were angry and happy faces presented in neutral backgrounds. Facial hair of the target faces was also manipulated. An anger superiority effect emerged that was augmented by the presence of facial hair, which was due to the slower detection of happiness on bearded faces. In Study 3, targets were happy and angry faces presented in either bearded or clean-shaven backgrounds. Facial hair of the background faces was also systematically manipulated. A significant anger superiority effect was revealed, although this was not moderated by the target's facial hair. Rather, the anger superiority effect was larger in clean-shaven than bearded face backgrounds. Together, results suggest that facial hair does influence detection of emotional expressions in visual search, however, rather than facilitating an anger superiority effect as a potential threat detection system, facial hair may reduce detection of happy faces within the face in the crowd paradigm.
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Expressão Facial , Felicidade , Ira , Emoções , Face , Cabelo , Humanos , Tempo de ReaçãoRESUMO
OBJECTIVE: To analyze the safety and clinical impact of interventional cardiac catheter procedures in the management of early postoperative problems after completion of an extracardiac Fontan procedure. BACKGROUND: The mortality after Fontan procedure has consistently decreased over the last decade. The role of interventional catheterization to address early postoperative problems in this setting has not been studied systematically. METHODS: Over a 9.7-year period, 289 patients underwent an extracardiac fenestrated Fontan procedure with two early deaths (0.7%) and takedown in four (1.4%). Twenty-seven patients (9.3%) underwent 32 interventional cardiac catheter procedures at a median interval of 12.2 (1-30) days. The median weight was 14.5 (13.5-25) kg. The case notes and procedure records were reviewed retrospectively. RESULTS: Fontan pathway obstructions were treated in 11 patients with stent implantation with good results and no complications. Stent fenestration of the Fontan circulation was performed in 16 patients with one episode of transient hemiparesis and one episode of pericardial effusion. Three patients underwent initial balloon dilatation of branch pulmonary arteries or fenestration with little effect and underwent stent treatment 6 (5-9) days later. One patient had device closure of a large atrial fenestration. In one patient, residual anterograde pulmonary blood flow was occluded using a device. There were no deaths and in-hospital course was improved in all. CONCLUSION: Interventional cardiac catheter procedures can be performed safely and effectively in the early postoperative period after Fontan completion to address hemodynamic problems. These techniques contribute significantly to achieve a very low mortality and address morbidity after Fontan completion.
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Cateterismo Cardíaco , Técnica de Fontan/efeitos adversos , Cardiopatias Congênitas/cirurgia , Complicações Pós-Operatórias/terapia , Cateterismo Cardíaco/efeitos adversos , Cateterismo Cardíaco/instrumentação , Cateterismo Cardíaco/mortalidade , Cateterismo , Criança , Pré-Escolar , Inglaterra , Feminino , Técnica de Fontan/mortalidade , Cardiopatias Congênitas/mortalidade , Cardiopatias Congênitas/fisiopatologia , Hemodinâmica , Humanos , Masculino , Seleção de Pacientes , Complicações Pós-Operatórias/etiologia , Complicações Pós-Operatórias/mortalidade , Complicações Pós-Operatórias/fisiopatologia , Estudos Retrospectivos , Medição de Risco , Stents , Fatores de Tempo , Resultado do TratamentoRESUMO
Using an extended-cavity femtosecond oscillator, we investigated optical breakdown in BK7 glass caused by the accumulated action of many laser pulses. By using a pump-probe experiment and collecting the transmitted pump along with the reflected pump and the broadband light generated by the optical breakdown, we measured the build-up time to optical breakdown as a function of the pulse energy, and we also observed the instability of the plasma due to the effect of defocusing and shielding created by the electron gas. The spectrum of the broadband light emitted by the optical breakdown and the origin of the material modification in BK7 glass was studied. We developed a simple model of electromagnetic wave propagation in plasma that is consistent with the observed behavior of the reflection, absorption, and transmission of the laser light.
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Gases/química , Vidro/química , Vidro/efeitos da radiação , Lasers , Modelos Químicos , Simulação por Computador , Relação Dose-Resposta à Radiação , Gases/efeitos da radiação , Transição de Fase/efeitos da radiação , Doses de RadiaçãoRESUMO
Persistent primitive hypoglossal artery is a carotid-vertebrobasilar anastomosis, which commonly arises from the internal carotid artery at the level of the C (cervical) 1-3 vertebrae. We describe a unique case of a female infant patient with this anomaly that has an unusually low origin from the distal common carotid artery just below the bifurcation at the level of roughly C5 and supplies the entire vertebrobasilar system. Additional cardiovascular anatomical variations were present: Tetralogy of Fallot and a right-sided aortic arch with mirror image branching. These singular variations are rare in the general population, but even rarer when combined. Awareness of these unusual vascular variants is clinically significant, as they may predispose the patients to early ischemic injury, hemorrhage, aneurysm formation, and can be essential in surgical planning. Therefore, radiographic imaging is of importance in proper diagnosis of such variants.
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Anormalidades Múltiplas/diagnóstico por imagem , Artéria Basilar/anormalidades , Artéria Basilar/diagnóstico por imagem , Artéria Carótida Interna/anormalidades , Artéria Carótida Interna/diagnóstico por imagem , Artéria Vertebral/anormalidades , Artéria Vertebral/diagnóstico por imagem , Aorta Torácica/anormalidades , Aorta Torácica/diagnóstico por imagem , Feminino , Humanos , Recém-Nascido , Angiografia por Ressonância Magnética , Tetralogia de Fallot/diagnóstico por imagemRESUMO
The dynamics of the furanose rings in the GCGC moiety of the DNA oligomer [d(G 1A 2T 3A 4 G 5 C 6 G 7 C 8T 9A 10T 11C 12)] 2 are studied by using deuterium solid-state NMR (SSNMR). SSNMR spectra obtained from DNAs selectively deuterated on the furanose rings of nucleotides within the 5'-GCGC-3' moiety indicated that all of these positions are structurally flexible. The furanose ring within the deoxycytidine that is the methylation target displays the largest-amplitude structural changes according to the observed deuterium NMR line shapes, whereas the furanose rings of nucleotides more remote from the methylation site have less-mobile furanose rings (i.e., with puckering amplitudes < 0.3 A). Previous work has shown that methylation reduces the amplitude of motion in the phosphodiester backbone of the same DNA, and our observations indicate that methylation perturbs backbone dynamics through the furanose ring. These NMR data indicate that the 5'-GCGC-3' is dynamic, with the largest-amplitude motions occurring nearest the methylation site. The inherent flexibility of this moiety in DNA makes the molecule more amenable to the large-amplitude structural rearrangements that must occur when the DNA binds to the HhaI methyltransferase.
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DNA/química , Desoxirribonucleases de Sítio Específico do Tipo II/química , Furanos/química , Ressonância Magnética Nuclear Biomolecular/métodos , Sítios de Ligação , DNA/síntese química , DNA/metabolismo , Metilação de DNA , Desoxicitidina/química , Desoxirribonucleases de Sítio Específico do Tipo II/metabolismo , Deutério/química , Modelos Químicos , Modelos Moleculares , Nucleosídeos/químicaRESUMO
The dynamics of the phosphodiester backbone in the [5'-GCGC-3'] 2 moiety of the DNA oligomer [d(G 1A 2T 3A 4 G 5 C 6 G 7 C 8T 9A 10T 11C 12)] 2 are studied using deuterium solid-state NMR (SSNMR). SSNMR spectra obtained from DNAs nonstereospecifically deuterated on the 5' methylene group of nucleotides within the [5'-GCGC-3'] 2 moiety indicated that all of these positions are structurally flexible. Previous work has shown that methylation reduces the amplitude of motion in the phosphodiester backbone and furanose ring of the same DNA, and our observations indicate that methylation perturbs backbone dynamics through not only a loss of mobility but also a change of direction of motion. These NMR data indicate that the [5'-GCGC-3'] 2 moiety is dynamic, with the largest amplitude motions occurring nearest the methylation site. The change of orientation of this moiety in DNA upon methylation may make the molecule less amenable to binding to the HhaI endonuclease.
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DNA-Citosina Metilases/química , DNA-Citosina Metilases/metabolismo , DNA/química , DNA/metabolismo , Sítios de Ligação , Simulação por Computador , Metilação de DNA , Deutério , Modelos Moleculares , Ressonância Magnética Nuclear Biomolecular/métodos , Conformação de Ácido Nucleico , Oligonucleotídeos/química , TermodinâmicaRESUMO
Tundra soils account for 50% of global stocks of soil organic carbon (SOC), and it is expected that the amplified climate warming in high latitude could cause loss of this SOC through decomposition. Decomposed SOC could become hydrologically accessible, which increase downstream dissolved organic carbon (DOC) export and subsequent carbon release to the atmosphere, constituting a positive feedback to climate warming. However, DOC export is often neglected in ecosystem models. In this paper, we incorporate processes related to DOC production, mineralization, diffusion, sorption-desorption, and leaching into a customized arctic version of the dynamic ecosystem model LPJ-GUESS in order to mechanistically model catchment DOC export, and to link this flux to other ecosystem processes. The extended LPJ-GUESS is compared to observed DOC export at Stordalen catchment in northern Sweden. Vegetation communities include flood-tolerant graminoids (Eriophorum) and Sphagnum moss, birch forest and dwarf shrub communities. The processes, sorption-desorption and microbial decomposition (DOC production and mineralization) are found to contribute most to the variance in DOC export based on a detailed variance-based Sobol sensitivity analysis (SA) at grid cell-level. Catchment-level SA shows that the highest mean DOC exports come from the Eriophorum peatland (fen). A comparison with observations shows that the model captures the seasonality of DOC fluxes. Two catchment simulations, one without water lateral routing and one without peatland processes, were compared with the catchment simulations with all processes. The comparison showed that the current implementation of catchment lateral flow and peatland processes in LPJ-GUESS are essential to capture catchment-level DOC dynamics and indicate the model is at an appropriate level of complexity to represent the main mechanism of DOC dynamics in soils. The extended model provides a new tool to investigate potential interactions among climate change, vegetation dynamics, soil hydrology and DOC dynamics at both stand-alone to catchment scales.
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Researchers have focused on preadolescents' appraisals, coping, and adjustment in the context of postdivorce interparental conflict, but have yet to assess their goals in these events. Fifty 9- to 12-year-old (52% female) preadolescents were interviewed to assess their goals for the coping strategies that they reported using in response to interparental conflict at home. The patterns observed were consistent with goal-oriented research in the peer conflict literature. Preadolescents reported goal orientations that matched (i.e., were functionally similar to) their respective behaviorally-based coping strategies, multiple goals for the same type of coping strategy, and multiple coping strategies for the same goal orientation. Relative to other coping strategies, preadolescents were more likely to choose a matching coping strategy to obtain social support, maintain self-boundary, and distraction goals. Relative to other goals, preadolescents' matching goal-strategy pairs occurred more frequently than nonmatching pairs, but these pairings accounted for about only one-third of the goals reported for a given strategy. Emotional regulation goal orientations more often than any other goal, which highlighted their importance in preadolescents coping with parental conflict. Finally, preadolescents' coping efforts were chosen for objectives beyond traditional category systems of coping, such as the personal characteristics of family members and others, helping others, and threats to self and others. Thus, the assessment of preadolescents' goals may improve our understanding of the motivations underlying their appraisals and coping strategies as they seek to adapt to interparental conflict environments.
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Países Desenvolvidos , Países em Desenvolvimento , Ecossistema , Efeito Estufa , Animais , Biodiversidade , Dióxido de Carbono , PlantasRESUMO
One of the primary functions of visual processing is to generate a spatial mapping of our immediate vicinity, in order to facilitate interaction. As yet it is unclear how this is achieved, but the process likely involves an accrual of information over time--a temporal integration of positional information (Eagleman & Sejnowski, 2000; Krekelberg et al., 2000). Temporal integration is a common computational process evident in diverse settings, such as electrical engineering (Bryson & Ho, 1975) and neural coding (Rao, Eagleman & Sejnowski, 2001; Usher & McClelland, 2001). In the later context it is sometimes assumed that integration dynamics are immobile, and consequently that they can be diagnostic of a sensory system (Arnold & Lipp, 2011; Krauskopf & Mollon, 1971; Snowden & Braddick, 1991). Other data suggest that integration times can be flexible, varying in concert with the properties of a stimulus (Bair & Movshon, 2004) or environment (Ossmy et al., 2013). Our data provide behavioral support for malleable integration times. We examine a motion-induced illusion of perceived position linked to temporal integration, and use prolonged exposure to motion of different speeds (sensory adaptation) to modulate the dynamics of neural activity. Results show that perceived position is governed by a weighted average of positional estimates from multiple channels with distinct, fixed integration times. Postadaptation channel contributions are reweighted, resulting in coding that is optimized to the dynamics of the prevailing environment.
Assuntos
Percepção de Movimento , Percepção do Tempo , Antecipação Psicológica , Feminino , Humanos , Masculino , Movimento (Física) , Estimulação Luminosa , Fatores de TempoRESUMO
The physiological blind spot refers to a zone of functional blindness all normally sighted people have in each eye, due to an absence of photoreceptors where the optic nerve passes through the surface of the retina. Here we report that the functional size of the physiological blind spot can be shrunk through training to distinguish direction signals at the blind spot periphery. Training on twenty successive weekdays improved sensitivity to both direction and colour, suggesting a generalizable benefit. Training on one blind spot, however, did not transfer to the blind spot in the untrained eye, ruling out mediation via a generic practice effect; nor could training benefits be attributed to eye movements, which were monitored to ensure stable fixation. These data suggest that training enhances the response gains of neurons with receptive fields that partially overlap, or abut, the physiological blind spot, thereby enhancing sensitivity to weak signals originating primarily from within the functionally-defined region of blindness [1-3]. Our results have important implications for situations where localised blindness has been acquired through damage to components of the visual system [4,5], and support proposals that these situations might be improved through perceptual training [5-7].
Assuntos
Disco Óptico/fisiologia , Campos Visuais , Percepção Visual , Humanos , Neurônios/fisiologia , Estimulação LuminosaRESUMO
In order to extend the operating range of the GEC RF Reference Cell, we developed an inductively coupled plasma source that replaced the standard parallel-plate upper-electrode assembly. Voltage and current probes, Langmuir probes, and an 80 GHz interferometer provided information on plasmas formed in argon, chlorine, and nitrogen at pressures from 0.1 Pa to 3 Pa. For powers deposited in the plasma from 20 W to 300 W, the source produced peak electron densities between 1010/cm3 and 1012/cm3 and electron temperatures near 4 eV. The electron density peaked on axis with typical full-width at half maximum of 7 cm to 9 cm. Discharges in chlorine and nitrogen had bimodal operation that was clearly evident from optical emission intensity. A dim mode occurred at low power and a bright mode at high power. The transition between modes had hysteresis. After many hours of high-power operation, films formed on electrodes and walls of one Cell. These deposits affected the dim-to-bright mode transition, and also apparently caused generation of hot electrons and increased the plasma potential.
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OBJECTIVE: To assess the indication, technical aspects, and outcome of stenting of the right ventricular outflow tract (RVOT) in the management of symptomatic patients with severely limited pulmonary blood flow. METHODS: Retrospective case note and procedure review of patients undergoing stenting of the RVOT over an 8 year period. PATIENTS: Between 2005 and 2012, 52 selected patients underwent percutaneous stent implantation into a very narrow RVOT to improve pulmonary blood flow. Median age at stent implantation was 63 (range 4-406) days and median weight was 3.8 (1.7-12.2) kg. RESULTS: 52 patients underwent stent implantation. Median procedure time was 57 (24-260) min and fluoroscopy time 16 (5.5-73) min. There was one procedural death (1.9%) and one emergency surgery (1.9%). Saturations increased from 71% (52-83%) to 92% (81-100%) (p<0.001). Two patients required early shunts due to inadequate palliation and two died from non-cardiac causes. Sixteen further catheter interventions were undertaken (balloon in 7, further stent in 9). Twenty-nine patients underwent delayed surgery (complete repair in 26, palliative in 3) at a median of 172 (52-758) days post-stenting. Left pulmonary artery Z score increased from a pre-interventional value of -1.75 (-4.96 to 0.67) to a pre-surgical value of -0.55 (-4.12 to 1.97), (p<0.01). Median right pulmonary artery Z score increased from -2.63 (-7.70 to 0.89) to -0.75 (-6.69 to 1.18) (p<0.01) . Seventeen patients remain well palliated after a median of 122 (40-286) days. CONCLUSIONS: Stenting of the RVOT is an effective treatment option in the initial management of selected patients with very reduced pulmonary blood flow.