RESUMO
The discovery of superconductivity at 200 kelvin in the hydrogen sulfide system at high pressures1 demonstrated the potential of hydrogen-rich materials as high-temperature superconductors. Recent theoretical predictions of rare-earth hydrides with hydrogen cages2,3 and the subsequent synthesis of LaH10 with a superconducting critical temperature (Tc) of 250 kelvin4,5 have placed these materials on the verge of achieving the long-standing goal of room-temperature superconductivity. Electrical and X-ray diffraction measurements have revealed a weakly pressure-dependent Tc for LaH10 between 137 and 218 gigapascals in a structure that has a face-centred cubic arrangement of lanthanum atoms5. Here we show that quantum atomic fluctuations stabilize a highly symmetrical [Formula: see text] crystal structure over this pressure range. The structure is consistent with experimental findings and has a very large electron-phonon coupling constant of 3.5. Although ab initio classical calculations predict that this [Formula: see text] structure undergoes distortion at pressures below 230 gigapascals2,3, yielding a complex energy landscape, the inclusion of quantum effects suggests that it is the true ground-state structure. The agreement between the calculated and experimental Tc values further indicates that this phase is responsible for the superconductivity observed at 250 kelvin. The relevance of quantum fluctuations calls into question many of the crystal structure predictions that have been made for hydrides within a classical approach and that currently guide the experimental quest for room-temperature superconductivity6-8. Furthermore, we find that quantum effects are crucial for the stabilization of solids with high electron-phonon coupling constants that could otherwise be destabilized by the large electron-phonon interaction9, thus reducing the pressures required for their synthesis.
RESUMO
Gambling disorder (GD) is a form of behavioral addiction. In recent years, it has been suggested that the application of transcranial Direct Current Stimulation (tDCS) to the dorsolateral prefrontal cortex (DLPFC), which plays a key role in top-down inhibitory control and impulsivity, may represent a new therapeutic approach for treating addictions. Here we investigated the effectiveness of a novel low dose tDCS protocol (i.e. six sessions of right anodal/left cathodal tDCS for 20 min, with a current intensity of 1 mA) applied to DLPFC in a patient with GD. To evaluate the effect of the proposed intervention, cognitive, psychological and behavioural evaluations were performed at different time points, pre and post intervention. The results showed improvement of impulsivity, decision making, and cognitive functioning after tDCS intervention. Findings of the present study suggest that low doses of right anodal/left cathodal tDCS to DLPFC may effectively improve gambling behaviour. They also suggest to carefully evaluate the effects of this tDCS polarity on the patient's emotional state. The current protocol warrants further investigation in large groups of patients, as it may provide relevant insights into the design of effective, low dose treatments of gambling disorder.
Assuntos
Jogo de Azar , Estimulação Transcraniana por Corrente Contínua , Tomada de Decisões/fisiologia , Córtex Pré-Frontal Dorsolateral , Jogo de Azar/psicologia , Humanos , Comportamento Impulsivo , Córtex Pré-Frontal/fisiologia , Estimulação Transcraniana por Corrente Contínua/métodosRESUMO
Cognition is shaped by signals from outside and within the body. Following recent evidence of interoceptive signals modulating higher-level cognition, we examined whether breathing changes the production and perception of quantities. In Experiment 1, 22 adults verbally produced on average larger random numbers after inhaling than after exhaling. In Experiment 2, 24 further adults estimated the numerosity of dot patterns that were briefly shown after either inhaling or exhaling. Again, we obtained on average larger responses following inhalation than exhalation. These converging results extend models of situated cognition according to which higher-level cognition is sensitive to transient interoceptive states.
Assuntos
Interocepção , Adulto , Cognição , Humanos , RespiraçãoRESUMO
Considering recent findings that breathing influences cognitive processes, two experiments explored the relationship between breathing and visuo-spatial attention. In Experiment 1, a lateralized probe detection task was inserted into the breathing cycles of 21 healthy adults to probe effects of breathing on the distribution of spatial attention. In Experiment 2 (N = 26), the Posner cueing task measured breathing-contingent detection speed for lateralized probes after endogenous or exogenous cueing. We consistently found faster responses for left probes after exhalation and for right probes after inhalation in both experiments. Breathing also affected the speed of re-alignment of spatial attention after invalid cueing in Experiment 2. This novel breathing bias shows that our ability to encode visuo-spatial information systematically fluctuates during breathing.
Assuntos
Atenção , Percepção Espacial , Adulto , Humanos , Percepção Espacial/fisiologia , Atenção/fisiologia , Sinais (Psicologia) , Tempo de Reação/fisiologiaRESUMO
OBJECTIVES AND DESIGN: To date, no sufficiently sensitive and specific single marker has been found to predict the clinical course of sarcoidosis. We designed a cohort study to investigate whether a panel of biomarkers measured in bronchoalveolar lavage (BAL) and peripheral blood could help predict pulmonary function worsening during the clinical course of sarcoidosis. METHODS: We analyzed 30 individuals with histologically proven sarcoidosis. At baseline, participants underwent pulmonary function tests (PFTs), fiberoptic bronchoscopy and radiological investigations. BAL and blood cellular profiles were obtained from all individuals and six pro-inflammatory molecules were quantified in BAL and serum. PFTs were performed at follow-up visits over a 2-year period. Using discriminant function analysis, a canonical variable was generated to optimize the accuracy of selected variables in predicting pulmonary function worsening and was validated on a subset of nine consecutive individuals with sarcoidosis. RESULTS: A combination of 6 markers from BAL was able to predict pulmonary function worsening in 96 % of patients [95 % confidence interval (CI) 84.4-99.81]. We validated the generated formula on a group of nine patients with sarcoidosis, obtaining 77.8 % correct classification (95 % CI 45.3-93.7). CONCLUSIONS: Our results show that a combinational approach could contribute to identifying individuals likely to experience pulmonary function worsening, thus helping to decide the correct therapeutic strategies.
Assuntos
Progressão da Doença , Inflamação/metabolismo , Inflamação/fisiopatologia , Pulmão/metabolismo , Pulmão/fisiopatologia , Sarcoidose Pulmonar/metabolismo , Sarcoidose Pulmonar/fisiopatologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Biomarcadores/metabolismo , Lavagem Broncoalveolar , Broncoscopia , Estudos de Coortes , Proteína Catiônica de Eosinófilo/metabolismo , Feminino , Seguimentos , Humanos , Estudos Longitudinais , Masculino , Pessoa de Meia-Idade , Fragmentos de Peptídeos/metabolismo , Peroxidase/metabolismo , Pró-Colágeno/metabolismo , Receptores de Interleucina-2/metabolismo , Testes de Função Respiratória , Sensibilidade e Especificidade , Triptases/metabolismo , Fator de Necrose Tumoral alfa/metabolismoRESUMO
By analyzing structural and electronic properties of more than a hundred predicted hydrogen-based superconductors, we determine that the capacity of creating an electronic bonding network between localized units is key to enhance the critical temperature in hydrogen-based superconductors. We define a magnitude named as the networking value, which correlates with the predicted critical temperature better than any other descriptor analyzed thus far. By classifying the studied compounds according to their bonding nature, we observe that such correlation is bonding-type independent, showing a broad scope and generality. Furthermore, combining the networking value with the hydrogen fraction in the system and the hydrogen contribution to the density of states at the Fermi level, we can predict the critical temperature of hydrogen-based compounds with an accuracy of about 60 K. Such correlation is useful to screen new superconducting compounds and offers a deeper understating of the chemical and physical properties of hydrogen-based superconductors, while setting clear paths for chemically engineering their critical temperatures.
RESUMO
Phosphenes ("light flashes") have been reported by most astronauts on space missions and by healthy subjects whose eyes were exposed to ionizing radiation in early experiments in particle accelerators. The conditions of occurrence suggested retinal effects of heavy ions. To develop an in vivo animal model, we irradiated the eyes of anesthetized wild-type mice with repeated bursts of 12C ions delivered under controlled conditions in accelerator. 12C ions evoked electrophysiological retinal mass responses and activated the visual system as indicated by responses recorded from the visual cortex. No retinal immunohistological damage was detected. Mice proved a suitable animal model to study radiation-induced phosphenes in vivo and our findings are consistent with an origin of phosphenes in radiation activating the retina.
Assuntos
Carbono , Íons Pesados , Retina/efeitos da radiação , Córtex Visual/fisiologia , Animais , Eletrorretinografia/métodos , Feminino , Camundongos , Camundongos Endogâmicos C57BL , Proteínas do Tecido Nervoso/metabolismo , Fosfenos/efeitos da radiação , Retina/anatomia & histologia , Córtex Visual/efeitos da radiação , Vias Visuais/fisiologia , Vias Visuais/efeitos da radiaçãoRESUMO
The possibility of working in high count rate conditions is an important issue for neutron measurements applied to fusion experiments in order to extend the measurement dynamic range and time resolution. One of the main issues of high count rate operation is the overlapping of closely spaced events (pileup) that produces a distortion in their amplitude and therefore in the pulse height spectra. The usual way to deal with such pileup events using standard analog electronics is to reject them in the energy analysis process. Thanks to digital acquisition techniques, the waveforms of pileup events can be recorded and elaborated in order to reconstruct the contributing original single events. This work presents the results of the application of a pileup resolving method for the reconstruction and analysis of overlapping events to pulses acquired digitally from a NE213 liquid scintillator detector. The measurements have been carried out at the PTB accelerator facility with 14 MeV neutrons at total count rates over 400 kHz.