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Jhanas are profound states of mind achieved through advanced meditation, offering valuable insights into the nature of consciousness and tools to enhance well-being. Yet, its neurophenomenology remains limited due to methodological difficulties and the rarity of advanced meditation practitioners. We conducted a highly exploratory study to investigate the neurophenomenology of jhanas in an intensively sampled adept meditator case study (4 hr 7T fMRI collected in 27 sessions) who performed jhana meditation and rated specific aspects of experience immediately thereafter. Linear mixed models and correlations were used to examine relations among brain activity and jhana phenomenology. We identified distinctive patterns of brain activity in specific cortical, subcortical, brainstem, and cerebellar regions associated with jhana. Furthermore, we observed correlations between brain activity and phenomenological qualities of attention, jhanic qualities, and narrative processing, highlighting the distinct nature of jhanas compared to non-meditative states. Our study presents the most rigorous evidence yet that jhana practice deconstructs consciousness, offering unique insights into consciousness and significant implications for mental health and well-being.
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Meditação , Humanos , Meditação/psicologia , Estado de Consciência , Atenção , Imageamento por Ressonância Magnética , Encéfalo/diagnóstico por imagemRESUMO
Advanced meditation such as jhana meditation can produce various altered states of consciousness (jhanas) and cultivate rewarding psychological qualities including joy, peace, compassion, and attentional stability. Mapping the neurobiological substrates of jhana meditation can inform the development and application of advanced meditation to enhance well-being. Only two prior studies have attempted to investigate the neural correlates of jhana meditation, and the rarity of adept practitioners has largely restricted the size and extent of these studies. Therefore, examining the consistency and reliability of observed brain responses associated with jhana meditation can be valuable. In this study, we aimed to characterize functional magnetic resonance imaging (fMRI) reliability within a single subject over repeated runs in canonical brain networks during jhana meditation performed by an adept practitioner over 5 days (27 fMRI runs) inside an ultra-high field 7 Tesla MRI scanner. We found that thalamus and several cortical networks, that is, the somatomotor, limbic, default-mode, control, and temporo-parietal, demonstrated good within-subject reliability across all jhanas. Additionally, we found that several other relevant brain networks (e.g., attention, salience) showed noticeable increases in reliability when fMRI measurements were adjusted for variability in self-reported phenomenology related to jhana meditation. Overall, we present a preliminary template of reliable brain areas likely underpinning core neurocognitive elements of jhana meditation, and highlight the utility of neurophenomenological experimental designs for better characterizing neuronal variability associated with advanced meditative states.
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Imageamento por Ressonância Magnética , Meditação , Rede Nervosa , Humanos , Reprodutibilidade dos Testes , Rede Nervosa/fisiologia , Rede Nervosa/diagnóstico por imagem , Adulto , Masculino , Feminino , Encéfalo/fisiologia , Encéfalo/diagnóstico por imagem , Córtex Cerebral/fisiologia , Córtex Cerebral/diagnóstico por imagemRESUMO
Mesoporous catalysts with a high specific surface area, accessible pore structures, and appropriate band edges are desirable for optimal charge transfer across the interfaces, suppress electron-hole recombination, and promote redox reactions at the active sites. The present study demonstrates the rational design of mesoporous ZnFe2O4@g-C3N4 magnetic nanocomposites (MNCs) with different pore sizes and pore volumes following a combination of facile thermal itching and thermal impregnation methods. The MNCs preserve the structural, morphological, and physical attributes of their counterparts while ensuring their effectiveness and superior catalytic capabilities. The morphological analysis confirms the successful grafting and confinement of ZnFe2O4 nanoparticles with the polymeric g-C3N4 nanosheets to form heterojunctions with numerous interfaces. The MNCs possess uniformly distributed small mesopores (pore size <4 nm), ample active sites, and a high specific surface area of 62.50 m2/g. The mesoporous ZnFe2O4@g-C3N4 notably improve hydrogen evolution rate and methylene blue dye degradation. The optimal loading weight of ZnFe2O4 is 20%, in which the MNCs display the highest hydrogen evolution rate of 1752 µmolg-1h-1 and photo-Fenton dye degradation rate constants of 0.147 min-1, upon solar-light illumination. Furthermore, the photocatalysts demonstrate recyclability over five consecutive cycles, confirming their stability, while easy separation using a simple magnet underscores practical utility.
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Mindfulness meditation is a contemplative practice that is informed by Buddhism. It has been proven effective for improving mental and physical health in clinical and non-clinical contexts. To date, mainstream dialogue and scientific research on mindfulness has focused primarily on short-term mindfulness training and applications of mindfulness for reducing stress. Understanding advanced mindfulness practice has important implications for mental health and general wellbeing. According to Theravada Buddhist meditation, a "cessation" event is a dramatic experience of profound clarity and equanimity that involves a complete discontinuation in experience, and is evidence of mastery of mindfulness meditation. Thirty-seven cessation events were captured in a single intensively sampled advanced meditator (over 6,000 h of retreat mindfulness meditation training) while recording electroencephalography (EEG) in 29 sessions between November 12, 2019 and March 11, 2020. Functional connectivity and network integration were assessed from 40 s prior to cessations to 40 s after cessations. From 21 s prior to cessations there was a linear decrease in large-scale functional interactions at the whole-brain level in the alpha band. In the 40 s following cessations these interactions linearly returned to prior levels. No modulation of network integration was observed. The decrease in whole-brain functional connectivity was underlain by frontal to left temporal and to more posterior decreases in connectivity, while the increase was underlain by wide-spread increases in connectivity. These results provide neuroscientific evidence of large-scale modulation of brain activity related to cessation events that provides a foundation for future studies of advanced meditation.
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Humans anticipate and evaluate both obtained and counterfactual outcomes - outcomes that could have been had an alternate decision been taken - and experience associated emotions of regret and relief. Although many functional magnetic resonance imaging (fMRI) studies have examined the neural correlates of these emotions, there is substantial heterogeneity in their results. We conducted coordinate-based ALE and network-based ANM meta-analysis of fMRI studies of experienced regret and relief to examine commonalities and differences in their neural correlates. Regionally, we observed that the experience of both regret and relief was associated with greater activation in the right ventral striatum (VS), which is implicated in tracking reward prediction error. At the network level, regret and relief shared the reward-sensitive mesocorticolimbic network with preferential activation of the medial orbitofrontal cortex (mOFC) for regret processing and medial cingulate cortex (MCC) for relief processing. Our research identified shared and separable brain systems subserving regret and relief experience, which may inform the treatment of regret-related mood disorders.
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Comportamento de Escolha , Emoções , Humanos , Comportamento de Escolha/fisiologia , Emoções/fisiologia , Encéfalo/diagnóstico por imagem , Encéfalo/fisiologia , Córtex Pré-Frontal/fisiologia , Recompensa , Imageamento por Ressonância Magnética , Tomada de Decisões/fisiologiaRESUMO
The ability to adopt the perspectives of others is fundamental to effective communication in social interactions. However, the neural correlates of allocentric thinking in communicative signaling remain unclear. We adapted a novel signaling task in which the signaler was given the target word and must choose a one-word signal to help the receiver guess the target. Behavioral results suggest that speakers can use allocentric thinking to choose signals that are salient from the perspective of the receiver rather than their own point of view. At the neural level, functional magnetic resonance imaging (fMRI) data reveal that the medial prefrontal cortex (mPFC), ventral striatum, and temporal-parietal junction are more activated when signalers engage in allocentric than egocentric thinking. Moreover, functional connectivity between the mPFC and ventral striatum predicted individuals' perspective-taking ability during successful communication. These findings reveal that neural representations in the mPFC-striatum network support perspective-taking in complex social decision making, providing a new perspective on how the brain arbitrates between allocentric thinking and egocentric thinking in communication and social coordination.
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Corpo Estriado/fisiologia , Imageamento por Ressonância Magnética/métodos , Rede Nervosa/fisiologia , Córtex Pré-Frontal/diagnóstico por imagem , Córtex Pré-Frontal/fisiologia , Pensamento/fisiologia , Adulto , Corpo Estriado/diagnóstico por imagem , Feminino , Humanos , Masculino , Rede Nervosa/diagnóstico por imagem , Estimulação Luminosa/métodos , Distribuição Aleatória , Tempo de Reação/fisiologia , Adulto JovemRESUMO
Heterogeneous photocatalysis premised on advanced oxidation processes has witnessed a broad application perspective, including water purification and environmental remediation. In particular, the graphitic carbon nitride (g-C3N4), an earth-abundant metal-free conjugated polymer, has acquired extensive application scope and interdisciplinary consideration owing to its outstanding structural and physicochemical properties. However, several issues such as the high recombination rate of the photo-generated electron-hole pairs, smaller specific surface area, and lower electrical conductivity curtail the catalytic efficacy of bulk g-C3N4. Another challenging task is separating the catalyst from the reaction medium, limiting their reusability and practical applications. Therefore, several methodologies are adopted strategically to tackle these issues. Attention is being paid, especially to the magnetic nanocomposites (NCs) based catalysts to enhance efficiency and proficient reusability property. This review summarizes the latest progress related to the design and development of magnetic g-C3N4-based NCs and their utilization in photocatalytic systems. The usefulness of the semiconductor heterojunctions on the catalytic activity, working mechanism, and degradation of pollutants are discussed in detail. The major challenges and prospects of using magnetic g-C3N4-based NCs for photocatalytic applications are highlighted in this report.
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OBJECTIVE: Previous research has demonstrated a robust relationship between religion and well-being, and it has been proposed that positive emotions are important mediators of this effect. Yet the mechanism via which religion promotes positive emotions has not been widely studied. We sought to examine whether teleological explanations of daily events and resulting positive emotions serially mediated the effects of religion on well-being. METHOD: These hypotheses were tested over three studies involving full-time and part-time university students in Singapore. In Study 1, participants completed measures of religiousness and well-being, and explained and described three recent personally significant events and their resulting emotions. Studies 2 and 3 adopted an ecological momentary assessment approach to measure teleological explanations, resulting emotions, and well-being in almost real time. RESULTS: In Study 1, teleological explanations and positive emotions serially mediated the effects of religiousness on well-being. In Study 2, momentary teleological explanations of daily events mediated the positive relationship between religiousness and momentary positive emotions. In Study 3, serial mediation of the relationship between religiousness and momentary well-being by momentary teleological explanations and positive emotions was observed. CONCLUSIONS: These results provide evidence of the importance of teleological explanations of daily events in religious enhancement of well-being.
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Emoções , Qualidade de Vida/psicologia , Religião e Psicologia , Adulto , Teoria Ética , Feminino , Humanos , Masculino , Singapura , Estudantes , Universidades , Adulto JovemRESUMO
People are social animals who value social goods uniquely. In discussions about how economic policies are evaluated by the layperson, it is essential to consider how they may evoke repulsive social emotions such as disgust and anger. We propose that fear of economic policies is not general and that it is specific to items where markets tend to assault certain social values.
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Emoções , Medo , Ira , Cognição , AscoRESUMO
Single layer organic photovoltaic devices based on copper phthalocyanine (CuPc) sandwiched between indium tin oxide (ITO) coated glass substrate and aluminum (Al) electrode have been fabricated. The interface dipoles formed at the metal/organic interface play a key role in determining the barrier for charge (electron or hole) injection between the metal electrode and significantly affects the efficiency of organic based electronic and optoelectronic devices. The origin of interface dipoles formed at the metal/organic (Al/CuPc) interface is assumed to be the charge transfer process between the organics (CuPc) and the metal (Al) electrode. Such a device shows forward rectifying property under dark condition when ITO kept at positive bias and Al kept at negative bias. Negative differential resistance (NDR) effect has been observed at high reverse bias voltage. Under white light excitation the device shows reverse rectifying property with a high open circuit voltage. It appears that the interface dipoles formed at the Al/CuPc junction act as exciton dissociation centers. NDR effect can be explained due to charge accumulation layer at the AI/CuPc interface and hence interface dipoles and/or band bending in CuPc. Asymmetry in dark current-voltage (I-V) characteristics has been explained due to strengthening or weakening the dipole field on the application of reverse bias or forward bias at the junction interface, respectively. Various photovoltaic parameters have been calculated from the I-V characteristics of the devices under illumination through ITO electrode.
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Nanostructured organic-organic (O-O) heterojunction was fabricated by using the thin films of a hole transporting material, copper phthalocyanine (CuPc) and an electron transporting material, copper hexadecafluoro-phthalocyanine (F16CuPc). The nanostructured thin films were characterized by optical absorption spectra, FESEM, AFM, X-ray diffraction, etc. Grain size of CuPc and F16CuPc on the substrate surface was different. XRD analysis shows that the crystallinity of the double layer films/heterojunction decreases as compared to the single layer film. The heterojunction sandwich structure ITO/F16CuPc/CuPc/Al, in the present study has shown a good diode like current-voltage (I-V) characteristics with reverse rectifying characteristics. In addition, electrical switching and hysteresis phenomena have also been observed in both sides of the voltage polarities. Interestingly, the single layer sandwich structure of the type ITO/CuPc/Al and ITO/F16CuPc/Al did not show any noticeable electrical switching and hysteresis in I-V characteristics as compared to double layer heterostructure. The reverse rectification has been explained on the basis of band bending due to the accumulation of charge carriers near the junction and the electrical switching has been explained considering the charge carriers trapping and detrapping at the O-O interface.
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Eletrodos , Nanoestruturas/química , Nanoestruturas/ultraestrutura , Compostos Orgânicos/química , Semicondutores , Processamento de Sinais Assistido por Computador/instrumentação , Desenho de Equipamento , Análise de Falha de Equipamento , Tamanho da PartículaRESUMO
Over the last two decades, motivations for modified gravity have emerged from both theoretical and observational levels. f(R) and Chern-Simons gravity have received more attention as they are the simplest generalization. However, f(R) and Chern-Simons gravity contain only an additional scalar (spin-0) degree of freedom and, as a result, do not include other modes of modified theories of gravity. In contrast, quadratic gravity (also referred to as Stelle gravity) is the most general second-order modification to 4-D general relativity and contains a massive spin-2 mode that is not present in f(R) and Chern-Simons gravity. Using two different physical settings-the gravitational wave energy-flux measured by the detectors and the backreaction of the emitted gravitational radiation on the spacetime of the remnant black hole-we demonstrate that massive spin-2 mode carries more energy than the spin-0 mode. Our analysis shows that the effects are pronounced for intermediate-mass black holes, which are prime targets for LISA.
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Absence of consciousness can occur due to a concussion, anesthetization, intoxication, epileptic seizure, or other fainting/syncope episode caused by lack of blood flow to the brain. However, some meditation practitioners also report that it is possible to undergo a total absence of consciousness during meditation, lasting up to 7 days, and that these "cessations" can be consistently induced. One form of extended cessation (i.e., nirodha samapatti) is thought to be different from sleep because practitioners are said to be completely impervious to external stimulation. That is, they cannot be 'woken up' from the cessation state as one might be from a dream. Cessations are also associated with the absence of any time experience or tiredness, and are said to involve a stiff rather than a relaxed body. Emergence from meditation-induced cessations is said to have profound effects on subsequent cognition and experience (e.g., resulting in a sudden sense of clarity, openness, and possibly insights). In this paper, we briefly outline the historical context for cessation events, present preliminary data from two labs, set a research agenda for their study, and provide an initial framework for understanding what meditation induced cessation may reveal about the mind and brain. We conclude by integrating these so-called nirodha and nirodha samapatti experiences-as they are known in classical Buddhism-into current cognitive-neurocomputational and active inference frameworks of meditation.
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Concussão Encefálica , Meditação , Humanos , Estado de Consciência , Encéfalo , CogniçãoRESUMO
Mindfulness meditation is a contemplative practice informed by Buddhism that targets the development of present-focused awareness and non-judgment of experience. Interest in mindfulness is burgeoning, and it has been shown to be effective in improving mental and physical health in clinical and non-clinical contexts. In this report, for the first time, we used electroencephalography (EEG) combined with a neurophenomenological approach to examine the neural signature of "cessation" events, which are dramatic experiences of complete discontinuation in awareness similar to the loss of consciousness, which are reported to be experienced by very experienced meditators, and are proposed to be evidence of mastery of mindfulness meditation. We intensively sampled these cessations as experienced by a single advanced meditator (with over 23,000 h of meditation training) and analyzed 37 cessation events collected in 29 EEG sessions between November 12, 2019, and March 11, 2020. Spectral analyses of the EEG data surrounding cessations showed that these events were marked by a large-scale alpha-power decrease starting around 40 s before their onset, and that this alpha-power was lowest immediately following a cessation. Region-of-interest (ROI) based examination of this finding revealed that this alpha-suppression showed a linear decrease in the occipital and parietal regions of the brain during the pre-cessation time period. Additionally, there were modest increases in theta power for the central, parietal, and right temporal ROIs during the pre-cessation timeframe, whereas power in the Delta and Beta frequency bands were not significantly different surrounding cessations. By relating cessations to objective and intrinsic measures of brain activity (i.e., EEG power) that are related to consciousness and high-level psychological functioning, these results provide evidence for the ability of experienced meditators to voluntarily modulate their state of consciousness and lay the foundation for studying these unique states using a neuroscientific approach.
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Meditação , Atenção Plena , Humanos , Meditação/métodos , Meditação/psicologia , Eletroencefalografia , Encéfalo , Mapeamento EncefálicoRESUMO
Prior research highlights the importance of spirituality/religion (S/R) as it relates to several aspects of mental health and clinical interventions. This research has been expanded to include the concurrent examination of neurobiological correlates of S/R to elucidate potential biological mechanisms. However, the majority of neurobiological research on S/R has neglected mental health, and the relationship across all three of these domains (S/R, mental health, and neurobiology) remains unclear. This study systematically reviewed research concurrently examining S/R, mental health, and neurobiology, and rated the methodological quality of included studies. Eighteen identified studies were then included in an integrated literature review and discussion, regarding the neurobiological correlates of S/R as it pertains to depression, anxiety, alcohol/substance misuse, and psychosis. The majority of studies demonstrated moderate to high methodological quality. Findings highlight the need for additional studies in this area as well as research that includes validated assessment of S/R.
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Saúde Mental , Neurociências , HumanosRESUMO
The instability of organic-inorganic hybrid halide perovskites due to light, heat, and moisture restricts them for practical use despite having most suitable photovoltaic properties and higher power conversion efficiency. Several methods such as surface engineering, carbon electrode utilization, and optimization of the components are applied to increase the stability; still, it is far from the practical implementation. Moreover, the toxicity of Pb in most of the efficient hybrid halide perovskites is another major issue. It motivates us to search for a stable and Pb free perovskite solar cell. Hence, a systematic investigation within density functional theory has been made on the structural, electronic, and optical properties of RbMI3compounds (whereM= Ge and Sn). The structural properties such as lattice parameters, formation energy are calculated. The calculated negative formation energy confirms the chemical stability for both compounds. The electronic properties like partial density of states, band structures with Perdew-Burke-Ernzerhof, Tran-Blaha modified Becke-Johnson (TB-mBJ) and HSE06 are discussed. Band gaps are calculated for RbGeI3(2.645 eV) and RbSnI3(2.544 eV) with TB-mBJ potential, which is proved to estimate the band gap values accurately for inorganic solids. SOC influences the conduction band minimum without any changes in the valence band maximum and thus reduces band gaps to 2.021 for RbGeI3and 1.865 eV for RbSnI3. The optical properties like the real and imaginary part of the dielectric constants, absorption coefficients, refractive indices, and reflectivities have also been discussed. Further, transport properties like effective masses, binding energy of excitons, and spectroscopic limited maximum efficiency (SLME) are calculated for both RbMI3compounds. The excitons for both structures are found to be Frenkel type. SLME for RbGeI3and RbSnI3having the thickness of 0.5 µm at a temperature of 300 K are found as 16.5% and 18%, respectively. Finally, the possibility of RbGeI3and RbSnI3in the solar cell configuration with TiO2as the hole transporting material have been explored.
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In pure-coordination games where there are multiple Nash equilibria, the selection of coordinated responses is inexplicable by rational-choice theory - yet coordination is ubiquitous in daily interactions. The psychological game theory therefore evokes the idea of focal-points: some equilibria being chosen due to its salience, as well as through predicting (i.e., mentalizing) other's response. Previous work has been limited to investigating how structural atrophy relates to deficits in coordination, or how brain activations differ between intuitive and deliberated coordination. In this study, we investigated how the strategy of coordination is reflected in the brain, compared to when no coordination is required. Using functional near-infrared spectroscopy (fNIRS), we examined the neural correlates of deriving a response to a category where participants had to either answer freely (i.e., a survey) or try to match their response with another participant (i.e., coordinate). We found that the coordination trials elicited significantly larger changes in oxyhemoglobin [HbO] concentration than survey trials in frontopolar and lateral prefrontal cortex (PFC). Individual differences in behavioral focal index was significantly correlated with [HbO] concentration in lateral PFC. Granger Causality (GC) analysis revealed greater effective connectivity from frontopolar to lateral PFC, and less GC from lateral PFC to frontopolar in the coordination condition. Our findings highlight the crucial role of frontopolar and lateral PFC in human coordination.
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Mapeamento Encefálico , Córtex Pré-Frontal , Encéfalo/diagnóstico por imagem , Humanos , Córtex Pré-Frontal/diagnóstico por imagem , Espectroscopia de Luz Próxima ao InfravermelhoRESUMO
Objectives: People tend to become more generous as they grow older, which may reflect an increase in their ego-transcending motives (i.e., concern more for the benefit of recipients than of the benefactors). The current study aimed to examine evidence for an enhanced ego-transcending motive among older adults. Methods: We adapted the social-discounting framework to quantify generosity toward people of different social distances, ranging from socially close others (e.g., family and close friends) to socially distant others (e.g., total strangers), in both young and older adults. We hypothesized that the normative decrease in generosity as a function of social distance (e.g., less generous towards strangers compared to close friends) will be mitigated in older adults. Results: Our results supported that older adults were more generous toward socially distant others (i.e., less social discounting) compared to younger adults. Discussion: Thus, consistent with the idea that the elderly are more oriented to ego-transcending goals, older adults are generous even when their generosity is unlikely to be reciprocated.
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Envelhecimento/psicologia , Altruísmo , Distância Psicológica , Adulto , Fatores Etários , Idoso , Humanos , Pessoa de Meia-Idade , Adulto JovemRESUMO
BACKGROUND: Rehabilitation has been an integral part of management of COPD. Since the implementation of the standard rehabilitation protocol is hardly possible in the rural developing world, aiming to make a feasible alternate effort may be worthwhile. METHODS: COPD patients diagnosed through spirometry were first stabilized with 6 weeks of uniform pharmacotherapy. Subsequently, they were subjected to a curriculum-based intensive single-session intervention with education, bronchial hygiene, and exercise training. The latter involved whole body exercise, pursed lip breathing, and diaphragmatic exercise. The participants continued to practice the exercises under real-world encouragement and supervision from trained volunteers. The impact was appraised in terms of change in health status through COPD assessment test (CAT) score measurements at stabilization, and after 6 weeks and 1 year of the intensive training and education. RESULTS: At stabilization, 70 out of 96 selected COPD subjects (73%) turned up (with mean age 62±9 years and mean FEV1 as 1.16±0.39 L) showing improvement as per CAT score (p=0.0001) from pharmacotherapy. After practicing the imparted education and training for 6 weeks, all these 70 participants had further significant improvement in the health status (n=70, p=0.00001). This improvement, been reinforced and supervised, continued to last even at 1 year (n=54, p=0.0001). CONCLUSION: The self-managed practice of a single-session education and training under real-world supervision can bring forth significant long-term improvement in the health status of COPD sufferers. Such simple and feasible intervention may substitute formal COPD rehabilitation programs in resource constraint situations.
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Terapia por Exercício , Educação de Pacientes como Assunto , Doença Pulmonar Obstrutiva Crônica/reabilitação , Qualidade de Vida , Medicamentos para o Sistema Respiratório/uso terapêutico , Autocuidado/métodos , Idoso , Exercícios Respiratórios/métodos , Terapia por Exercício/educação , Terapia por Exercício/métodos , Tolerância ao Exercício , Feminino , Disparidades nos Níveis de Saúde , Humanos , Índia/epidemiologia , Masculino , Pessoa de Meia-Idade , Educação de Pacientes como Assunto/métodos , Educação de Pacientes como Assunto/organização & administração , Serviços Preventivos de Saúde/organização & administração , Doença Pulmonar Obstrutiva Crônica/epidemiologia , Doença Pulmonar Obstrutiva Crônica/psicologia , Doença Pulmonar Obstrutiva Crônica/terapia , Melhoria de Qualidade , Serviços de Saúde Rural/normas , Espirometria/métodosRESUMO
Silver nanoparticles were prepared by microwave assisted method using silver nitrate as precursor in the presence of some ferrocene derivatives. The formation of the silver nanoparticles was monitored using UV-Vis spectroscopy. The UV-Vis spectroscopy revealed the formation of silver nanoparticles by exhibiting typical surface plasmon absorption band. The position of plasmon band (406-429 nm) was observed to depend on the nature of a particular ferrocene derivative used. TEM images indicated that the nanoparticles were spherical in shape and well-dispersed. Quantum dots (3.2 nm) were prepared by using ferrocenecarboxylic acid. The surface plasmon absorption band has shown red shift with increasing concentration of ferrocene derivative. For different duration of microwave heating time, intensity of absorption spectra in general was found to increase except in presence of ferrocene carbaldehyde where it decreased. Time-dependent spectra have indicated almost stable position of the surface plasmon band with increasing time of observation confirming that the as prepared silver nanoparticles did not aggregate with lapse of time.