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1.
Anaesthesia ; 77(12): 1376-1385, 2022 12.
Artigo em Inglês | MEDLINE | ID: mdl-36111390

RESUMO

Cardiac arrest in the peri-operative period is rare but associated with significant morbidity and mortality. Current reporting systems do not capture many such events, so there is an incomplete understanding of incidence and outcomes. As peri-operative cardiac arrest is rare, many hospitals may only see a small number of cases over long periods, and anaesthetists may not be involved in such cases for years. Therefore, a large-scale prospective cohort is needed to gain a deep understanding of events leading up to cardiac arrest, management of the arrest itself and patient outcomes. Consequently, the Royal College of Anaesthetists chose peri-operative cardiac arrest as the 7th National Audit Project topic. The study was open to all UK hospitals offering anaesthetic services and had a three-part design. First, baseline surveys of all anaesthetic departments and anaesthetists in the UK, examining respondents' prior peri-operative cardiac arrest experience, resuscitation training and local departmental preparedness. Second, an activity survey to record anonymised details of all anaesthetic activity in each site over 4 days, enabling national estimates of annual anaesthetic activity, complexity and complication rates. Third, a case registry of all instances of peri-operative cardiac arrest in the UK, reported confidentially and anonymously, over 1 year starting 16 June 2021, followed by expert review using a structured process to minimise bias. The definition of peri-operative cardiac arrest was the delivery of five or more chest compressions and/or defibrillation in a patient having a procedure under the care of an anaesthetist. The peri-operative period began with the World Health Organization 'sign-in' checklist or first hands-on contact with the patient and ended either 24 h after the patient handover (e.g. to the recovery room or intensive care unit) or at discharge if this occured earlier than 24 h. These components described the epidemiology of peri-operative cardiac arrest in the UK and provide a basis for developing guidelines and interventional studies.


Assuntos
Anestésicos , Parada Cardíaca , Humanos , Estudos Prospectivos , Parada Cardíaca/epidemiologia , Parada Cardíaca/etiologia , Parada Cardíaca/terapia , Anestesiologistas , Estudos de Coortes
3.
Ir Med J ; 115(1): 514, 2022 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-35279048

RESUMO

Aims We aimed to assess the rate of persisting severe symptomatic secondary mitral regurgitation (MR) in a newly diagnosed heart failure (HF) population following optimisation of guideline directed medical therapy (GDMT), cardiac resynchronisation therapy (CRT) and revascularisation. Methods We assessed all new patients referred to our hospital group's HF clinics. We retrospectively reviewed these patients at HF clinic enrolment, HF programme completion, as well as most recent follow up. Results Of the 242 new patients referred to our HF clinics, there were 10 patients (4.1%) who had either persisting symptomatic severe secondary MR at HF programme completion, or had undergone mitral valve surgery. There were no percutaneous mitral valve repairs at the time of these patients' referrals. The rates of ACE/ARB/ARNI, BB and MRA use were 87.8%, 94.1%, and 49.8% in those with mid ranged, or reduced ejection fraction. The rates of ICD and CRT therapy were 15.1% and 4.4% at follow up. Patients with severe MR had higher time adjusted rates of death or hospitalization for heart failure. Conclusion In a well-treated newly diagnosed HF population, repeat assessment at HF programme completion suggests 4.1% of patients have a persisting indication for percutaneous mitral valve repair based on persisting severe symptomatic secondary MR.


Assuntos
Insuficiência Cardíaca , Insuficiência da Valva Mitral , Antagonistas de Receptores de Angiotensina , Inibidores da Enzima Conversora de Angiotensina , Insuficiência Cardíaca/etiologia , Insuficiência Cardíaca/terapia , Humanos , Insuficiência da Valva Mitral/etiologia , Insuficiência da Valva Mitral/cirurgia , Estudos Retrospectivos , Resultado do Tratamento
4.
Eur J Appl Physiol ; 122(3): 769-779, 2022 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-35038023

RESUMO

PURPOSE: The force-velocity relationship of muscular contraction has been extensively studied. However, previous research has focussed either on isolated muscle or single-joint movements, whereas human movement consists of multi-joint movements (e.g. squatting). Therefore, the purpose of this study was to investigate the force-velocity relationship of isovelocity squatting. METHODS: Fifteen male participants (24 ± 2 years, 79.8 ± 9.1 kg, 177.5 ± 6 cm) performed isovelocity squats on a novel motorised isovelocity device (Kineo Training System) at three concentric (0.25, 0.5, and 0.75 m s-1) and three eccentric velocities (- 0.25, - 0.5, and - 0.75 m s-1). Peak vertical ground reaction forces, that occurred during the isovelocity phase, were collected using dual force plates (2000 Hz) (Kistler, Switzerland). RESULTS: The group mean squat force-velocity profile conformed to the typical in vivo profile, with peak vertical ground reaction forces during eccentric squatting being 9.5 ± 19% greater than isometric (P = 0.037), and occurring between - 0.5 and - 0.75 m s-1. However, large inter-participant variability was identified (0.84-1.62 × isometric force), with some participants being unable to produce eccentric forces greater than isometric. Sub-group analyses could not identify differences between individuals who could/could not produce eccentric forces above isometric, although those who could not tended to be taller. CONCLUSIONS: These finding suggest that variability exists between participants in the ability to generate maximum eccentric forces during squatting, and the magnitude of eccentric increase above isometric cannot be predicted solely based on a concentric assessment. Therefore, an assessment of eccentric capabilities may be required prior to prescribing eccentric-specific resistance training.


Assuntos
Extremidade Inferior/fisiologia , Contração Muscular/fisiologia , Músculo Esquelético/fisiologia , Fenômenos Biomecânicos , Humanos , Masculino , Força Muscular/fisiologia , Postura , Adulto Jovem
5.
Sci Rep ; 11(1): 21952, 2021 11 09.
Artigo em Inglês | MEDLINE | ID: mdl-34754055

RESUMO

Neural recordings made to date through various approaches-both in-vitro or in-vivo-lack high spatial resolution and a high signal-to-noise ratio (SNR) required for detailed understanding of brain function, synaptic plasticity, and dysfunction. These shortcomings in turn deter the ability to further design diagnostic, therapeutic strategies and the fabrication of neuro-modulatory devices with various feedback loop systems. We report here on the simulation and fabrication of fully configurable neural micro-electrodes that can be used for both in vitro and in vivo applications, with three-dimensional semi-insulated structures patterned onto custom, fine-pitch, high density arrays. These microelectrodes were interfaced with isolated brain slices as well as implanted in brains of freely behaving rats to demonstrate their ability to maintain a high SNR. Moreover, the electrodes enabled the detection of epileptiform events and high frequency oscillations in an epilepsy model thus offering a diagnostic potential for neurological disorders such as epilepsy. These microelectrodes provide unique opportunities to study brain activity under normal and various pathological conditions, both in-vivo and in in-vitro, thus furthering the ability to develop drug screening and neuromodulation systems that could accurately record and map the activity of large neural networks over an extended time period.


Assuntos
Encéfalo/fisiologia , Eletrodos Implantados , Microeletrodos , Neurônios/fisiologia , Convulsões/fisiopatologia , Animais , Simulação por Computador , Desenho de Equipamento , Camundongos , Camundongos Endogâmicos C3H , Ratos , Ratos Sprague-Dawley
6.
Anaesthesia ; 76(9): 1167-1175, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34005837

RESUMO

Between October 2020 and January 2021, we conducted three national surveys to track anaesthetic, surgical and critical care activity during the second COVID-19 pandemic wave in the UK. We surveyed all NHS hospitals where surgery is undertaken. Response rates, by round, were 64%, 56% and 51%. Despite important regional variations, the surveys showed increasing systemic pressure on anaesthetic and peri-operative services due to the need to support critical care pandemic demands. During Rounds 1 and 2, approximately one in eight anaesthetic staff were not available for anaesthetic work. Approximately one in five operating theatres were closed and activity fell in those that were open. Some mitigation was achieved by relocation of surgical activity to other locations. Approximately one-quarter of all surgical activity was lost, with paediatric and non-cancer surgery most impacted. During January 2021, the system was largely overwhelmed. Almost one-third of anaesthesia staff were unavailable, 42% of operating theatres were closed, national surgical activity reduced to less than half, including reduced cancer and emergency surgery. Redeployed anaesthesia staff increased the critical care workforce by 125%. Three-quarters of critical care units were so expanded that planned surgery could not be safely resumed. At all times, the greatest resource limitation was staff. Due to lower response rates from the most pressed regions and hospitals, these results may underestimate the true impact. These findings have important implications for understanding what has happened during the COVID-19 pandemic, planning recovery and building a system that will better respond to future waves or new epidemics.


Assuntos
Anestesia/métodos , COVID-19 , Cuidados Críticos/métodos , Pesquisas sobre Atenção à Saúde/métodos , Anestesia/estatística & dados numéricos , Cuidados Críticos/estatística & dados numéricos , Pesquisas sobre Atenção à Saúde/estatística & dados numéricos , Humanos , Pandemias , SARS-CoV-2 , Reino Unido
8.
Anaesthesia ; 76(4): 537-548, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33525063

RESUMO

The COVID-19 pandemic continues to cause critical illness and deaths internationally. Up to 31 May 2020, mortality in patients admitted to intensive care units (ICU) with COVID-19 was 41.6%. Since then, changes in therapeutics and management may have improved outcomes. Also, data from countries affected later in the pandemic are now available. We searched MEDLINE, Embase, PubMed and Cochrane databases up to 30 September 2020 for studies reporting ICU mortality among adult patients with COVID-19 and present an updated systematic review and meta-analysis. The primary outcome measure was death in intensive care as a proportion of completed ICU admissions, either through discharge from intensive care or death. We identified 52 observational studies including 43,128 patients, and first reports from the Middle East, South Asia and Australasia, as well as four national or regional registries. Reported mortality was lower in registries compared with other reports. In two regions, mortality differed significantly from all others, being higher in the Middle East and lower in a single registry study from Australasia. Although ICU mortality (95%CI) was lower than reported in June (35.5% (31.3-39.9%) vs. 41.6% (34.0-49.7%)), the absence of patient-level data prevents a definitive evaluation. A lack of standardisation of reporting prevents comparison of cohorts in terms of underlying risk, severity of illness or outcomes. We found that the decrease in ICU mortality from COVID-19 has reduced or plateaued since May 2020 and note the possibility of some geographical variation. More standardisation in reporting would improve the ability to compare outcomes from different reports.


Assuntos
COVID-19/epidemiologia , Cuidados Críticos/estatística & dados numéricos , Mortalidade Hospitalar , Humanos , Estudos Observacionais como Assunto/estatística & dados numéricos , Sistema de Registros/estatística & dados numéricos , SARS-CoV-2
10.
Anaesthesia ; 76(8): 1122-1128, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-33201514

RESUMO

Randomised controlled trials are the gold standard in clinical research, but remain rare due to their expense and a perceived lack of 'real-world' applicability. At the same time, there has been an exponential increase in routinely collected data which presents opportunities for audit, quality improvement, adverse event reporting and more efficient clinical research. Registry-based research benefits from reduced cost, large sample size and real-world applicability, with methodological developments, particularly registry-based randomised controlled trials and causal inference techniques, showing promise. Limitations include data quality and validity, the need for data linkage, the restrictions of fixed data fields, regulatory barriers, and privacy and security concerns. However, the principal factor hampering current efforts is a lack of anaesthesia-specific datasets in the UK and the fact that most surgical registries do not collect any anaesthetic data. This presents an opportunity for anaesthetists, through enhanced engagement and collaboration, to influence and improve the design of these datasets and increase the value and volume of data collected. Better datasets, coupled with a growing appreciation of new analysis methodologies, would allow significant progress towards realising the potential of routinely collected data for patient benefit. At the same time, work should begin on the development of a minimum dataset for anaesthesia to underpin new data sharing networks and, ideally, a national registry of anaesthesia.


Assuntos
Anestesia/métodos , Avaliação de Resultados da Assistência ao Paciente , Assistência Perioperatória/métodos , Sistema de Registros , Dados de Saúde Coletados Rotineiramente , Humanos
11.
Anaesthesia ; 75(10): 1340-1349, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32602561

RESUMO

The emergence of coronavirus disease 2019 (COVID-19) has led to high demand for intensive care services worldwide. However, the mortality of patients admitted to the intensive care unit (ICU) with COVID-19 is unclear. Here, we perform a systematic review and meta-analysis, in line with PRISMA guidelines, to assess the reported ICU mortality for patients with confirmed COVID-19. We searched MEDLINE, EMBASE, PubMed and Cochrane databases up to 31 May 2020 for studies reporting ICU mortality for adult patients admitted with COVID-19. The primary outcome measure was death in intensive care as a proportion of completed ICU admissions, either through discharge from the ICU or death. The definition thus did not include patients still alive on ICU. Twenty-four observational studies including 10,150 patients were identified from centres across Asia, Europe and North America. In-ICU mortality in reported studies ranged from 0 to 84.6%. Seven studies reported outcome data for all patients. In the remaining studies, the proportion of patients discharged from ICU at the point of reporting varied from 24.5 to 97.2%. In patients with completed ICU admissions with COVID-19 infection, combined ICU mortality (95%CI) was 41.6% (34.0-49.7%), I2  = 93.2%). Sub-group analysis by continent showed that mortality is broadly consistent across the globe. As the pandemic has progressed, the reported mortality rates have fallen from above 50% to close to 40%. The in-ICU mortality from COVID-19 is higher than usually seen in ICU admissions with other viral pneumonias. Importantly, the mortality from completed episodes of ICU differs considerably from the crude mortality rates in some early reports.


Assuntos
Betacoronavirus , Infecções por Coronavirus/mortalidade , Unidades de Terapia Intensiva , Pneumonia Viral/mortalidade , COVID-19 , Mortalidade Hospitalar , Humanos , Avaliação de Resultados em Cuidados de Saúde , Pandemias , Estudos Prospectivos , SARS-CoV-2
12.
Curr Cardiol Rep ; 22(7): 47, 2020 05 29.
Artigo em Inglês | MEDLINE | ID: mdl-32472218

RESUMO

PURPOSE OF REVIEW: This review was undertaken to summarise recent data relating to T1 and T2 relaxation times in the assessment of myocarditis using cardiac MRI, and the effect new studies have had on the established diagnostic criteria, leading to recently proposed revised criteria for the cardiac MRI assessment of myocarditis. RECENT FINDINGS: In 2018, updates to the 2009 Lake Louise Criteria (LLC) were proposed, based on studies showing improved accuracy of T1 mapping techniques over T1 signal intensity ratio-based imaging, although for the detection of myocardial oedema either T2-weighted images or increased T2 relaxation times can be used. Non-ischaemic distribution of scar on late gadolinium-enhanced (LGE) T1-weighted imaging remains in the newly revised criteria, which, although can have low sensitivity due to fibrosis presenting diffusely or due to CMR being performed early in the disease process before scar formation, remains in the LLC due to its high specificity. Early gadolinium enhancement has been removed from the LLC, as T1 quantification has higher diagnostic accuracy for the detection of myocardial injury. In the CMR assessment of myocarditis, T1 and T2 quantifications are now recommended over T1- and T2-weighted imaging. Late gadolinium enhancement in a non-ischaemic pattern remains in the updated criteria, whereas early gadolinium enhancement has been superseded by T1 quantification.


Assuntos
Meios de Contraste/administração & dosagem , Gadolínio/administração & dosagem , Imageamento por Ressonância Magnética/métodos , Miocardite/diagnóstico por imagem , Doença Aguda , Edema Cardíaco/diagnóstico , Humanos , Imagem Cinética por Ressonância Magnética , Espectroscopia de Ressonância Magnética , Miocárdio , Valor Preditivo dos Testes , Troponina/sangue
13.
FEMS Microbiol Lett ; 367(7)2020 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-32189002

RESUMO

African dust from the Sahara and Sahel regions of Northern Africa is blown intercontinental distances and is the highest portion of atmospheric dust generated each year. During the Northern Hemisphere summer months (boreal summer), these dust events travel into the Caribbean and southern United States. While viability assays, microscopy and bacterial amplicon analyses have shown that dust-associated microbes may be diverse, the specific microbial taxa that are transported intercontinental distances with these dust events remain poorly characterized. To provide new insights into these issues, five metagenomes of Saharan dust events occurring in the Caribbean, collected in the summer months of 2002 and 2008, were analyzed. The data revealed that similar microbial composition existed between three out of the five of the distinct dust events and that fungi were a prominent feature of the metagenomes compared to other environmental samples. These results have implications for better understanding of microbial transport through the atmosphere and may implicate that the dust-associated microbial load transiting the Atlantic with Saharan dust is similar from year to year.


Assuntos
Poeira , Metagenoma , Atmosfera , Bactérias/genética , Poeira/análise , Monitoramento Ambiental , Estados Unidos
14.
Anaesthesia ; 75(5): 626-633, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32030735

RESUMO

We conducted a survey and semi-structured qualitative interviews to investigate current anaesthetic practice for arteriovenous fistula formation surgery in the UK. Responses were received from 39 out of 59 vascular centres where arteriovenous access surgery is performed, a response rate of 66%. Thirty-five centres reported routine use of brachial plexus blocks, but variation in anaesthetic skill-mix and practice were observed. Interviews were conducted with 19 clinicians from 10 NHS Trusts including anaesthetists, vascular access and renal nurses, surgeons and nephrologists. Thematic analysis identified five key findings: (1) current anaesthetic practice showed that centres could be classified as 'regional anaesthesia dominant' or 'local anaesthesia/mixed'; (2) decision making around mode of anaesthesia highlighted the key role of surgeons as frontline decision makers across both centre types; (3) perceived barriers and facilitators of regional block use included clinicians' beliefs and preferences, resource considerations and patients' treatment preferences; (4) anaesthetists' preference for supraclavicular blocks emerged, alongside acknowledgement of varied practice; (5) there was widespread support for a future randomised controlled trial, although clinician equipoise issues and logistical/resource-related concerns were viewed as potential challenges. The use of regional anaesthesia for arteriovenous fistula formation in the UK is varied and influenced by a multitude of factors. Despite the availability of anaesthetists capable of performing regional blocks, there are other limiting factors that influence the routine use of this technique. The study also highlighted the perceived need for a large multicentre, randomised controlled trial to provide an evidence base to inform current practice.


Assuntos
Anestesia por Condução/estatística & dados numéricos , Fístula Arteriovenosa/cirurgia , Procedimentos Cirúrgicos Vasculares/métodos , Adulto , Anestesia Local/estatística & dados numéricos , Anestesiologistas , Anestesistas , Bloqueio do Plexo Braquial , Tomada de Decisão Clínica , Feminino , Humanos , Masculino , Cirurgiões , Inquéritos e Questionários , Reino Unido
15.
Br J Surg ; 107(2): e142-e150, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31368512

RESUMO

BACKGROUND: Although delivering a chosen mode of anaesthesia for certain emergency surgery procedures is potentially beneficial to patients, it is a complex intervention to evaluate. This qualitative study explored clinician and patient perspectives about mode of anaesthesia for emergency surgery. METHODS: Snowball sampling was used to recruit participants from eight National Health Service Trusts that cover the following three emergency surgery settings: ruptured abdominal aortic aneurysms, hip fractures and inguinal hernias. A qualitative researcher conducted interviews with clinicians and patients. Thematic analysis was applied to the interview transcripts. RESULTS: Interviews were conducted with 21 anaesthetists, 21 surgeons, 14 operating theatre staff and 23 patients. There were two main themes. The first, impact of mode of anaesthesia in emergency surgery, had four subthemes assessing clinician and patient ideas about: context and the 'best' mode of anaesthesia; balance in choosing it over others; change and developments in anaesthesia; and the importance of mode of anaesthesia in emergency surgery. The second, tensions in decision-making about mode of anaesthesia, comprised four subthemes: clinical autonomy and guidelines in anaesthesia; conforming to norms in mode of anaesthesia; the relationship between expertise, preference and patient involvement; and team dynamics in emergency surgery. The results highlight several interlinking factors affecting decision-making, including expertise, preference, habit, practicalities, norms and policies. CONCLUSION: There is variation in practice in choosing the mode of anaesthesia for surgery, alongside debate as to whether anaesthetic autonomy is necessary or results in a lack of willingness to change.


ANTECEDENTES: Si bien determinados tipos de anestesia en ciertos procedimientos quirúrgicos de urgencia pueden ser potencialmente beneficiosos para los pacientes, la decisión de su utilización es difícil de evaluar. Este estudio cualitativo exploró las perspectivas del clínico y del paciente sobre sobre el tipo de anestesia en cirugía de urgencia. MÉTODOS: Se utilizó un muestreo de bola de nieve para reclutar participantes de 8 corporaciones del National Health Service (NHS) que cubrían tres entornos de cirugía de urgencia: rotura de aneurismas aórticos abdominales, fracturas de cadera y hernias inguinales. Un investigador cualitativo realizó 79 entrevistas a 21 anestesistas, 21 cirujanos, 14 técnicos de quirófano y 23 pacientes. Se realizó un análisis de las transcripciones de la entrevista por temas. RESULTADOS: Dos fueron los temas principales. El primero era el impacto del tipo de anestesia en la cirugía de urgencia y tenía 4 subtemas que evaluaban las ideas del clínico y del paciente sobre: el contexto y el mejor tipo de anestesia, las ventajas e inconvenientes de la elección de un tipo sobre los otros, los cambios y avances en anestesia, y la importancia de la anestesia en cirugía de urgencias. El segundo era las dificultades en la toma de decisiones sobre el tipo de anestesia y comprendía 4 subtemas: la autonomía clínica y las guías de anestesia, el seguimiento de las normas en el tipo de anestesia, la relación entre experiencia, preferencia y opinión del paciente, así como las dinámicas del equipo en cirugía de urgencia. Los resultados resaltaron varios factores interconectados que afectan la toma de decisiones, incluyen la experiencia, las preferencias, los hábitos, algunos aspectos prácticos, las normas y las políticas. CONCLUSIÓN: En la práctica, existen variaciones en la elección del tipo de anestesia para la cirugía, junto con el debate sobre si la autonomía anestésica es necesaria o si resulta en una falta de voluntad para el cambio.


Assuntos
Anestesia/métodos , Emergências , Pacientes , Cirurgiões , Procedimentos Cirúrgicos Operatórios/métodos , Humanos , Entrevistas como Assunto , Pacientes/psicologia , Autonomia Profissional , Cirurgiões/psicologia
16.
Plant Biol (Stuttg) ; 22 Suppl 1: 123-132, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31532043

RESUMO

The stimulatory effect of elevated [CO2 ] (e[CO2 ]) on crop production in future climates is likely to be cancelled out by predicted increases in average temperatures. This effect may become stronger through more frequent and severe heat waves, which are predicted to increase in most climate change scenarios. Whilst the growth and yield response of some legumes grown under the interactive effect of e[CO2 ] and heat waves has been studied, little is known about how N2 fixation and overall N metabolism is affected by this combination. To address these knowledge gaps, two lentil genotypes were grown under ambient [CO2 ] (a[CO2 ], ~400 µmol·mol-1 ) and e[CO2 ] (~550 µmol·mol-1 ) in the Australian Grains Free Air CO2 Enrichment facility and exposed to a simulated heat wave (3-day periods of high temperatures ~40 °C) at flat pod stage. Nodulation and concentrations of water-soluble carbohydrates (WSC), total free amino acids, N and N2 fixation were assessed following the imposition of the heat wave until crop maturity. Elevated [CO2 ] stimulated N2 fixation so that total N2 fixation in e[CO2 ]-grown plants was always higher than in a[CO2 ], non-stressed control plants. Heat wave triggered a significant decrease in active nodules and WSC concentrations, but e[CO2 ] had the opposite effect. Leaf N remobilization and grain N improved under interaction of e[CO2 ] and heat wave. These results suggested that larger WSC pools and nodulation under e[CO2 ] can support post-heat wave recovery of N2 fixation. Elevated [CO2 ]-induced accelerated leaf N remobilisation might contribute to restore grain N concentration following a heat wave.


Assuntos
Dióxido de Carbono , Temperatura Alta , Lens (Planta) , Fixação de Nitrogênio , Nitrogênio , Austrália , Dióxido de Carbono/metabolismo , Dióxido de Carbono/farmacologia , Meio Ambiente , Lens (Planta)/efeitos dos fármacos , Lens (Planta)/crescimento & desenvolvimento , Lens (Planta)/metabolismo , Nitrogênio/metabolismo
17.
Philos Trans A Math Phys Eng Sci ; 376(2134)2018 Oct 29.
Artigo em Inglês | MEDLINE | ID: mdl-30373945

RESUMO

Heaviside, in volume 1 of Electromagnetic theory, considered shielding of conducting materials in the form of attenuation. This treatment is still significant in the understanding of shielding effectiveness. He also considered propagation of electromagnetic waves in free-space. What Heaviside (1850-1925) could never have imagined is that 125 years later, there would be devices we know as mobile phones (or cell phones, handies, etc.) with capabilities beyond the dreams of the great science fiction writers of the day like H. G. Wells (1866-1949) or Jules Verne (1828-1905). More than this, that there would be a need for law enforcement agencies, among others, to use electromagnetically shielded enclosures to protect electronic equipment from communicating with the 'outside world'. Nevertheless, Heaviside's work is still fundamental to the developments discussed here. This paper provides a review of Heaviside's view of shielding and propagation provided in volume 1 of Electromagnetic theory and develops that to the design of new experiments to test the shielding of these portable enclosures in a mode-stirred reverberation chamber, a test environment that relies entirely on reflections from conducting surfaces for its operation.This article is part of the theme issue 'Celebrating 125 years of Oliver Heaviside's 'Electromagnetic Theory''.

18.
J Microsc ; 272(1): 12-24, 2018 10.
Artigo em Inglês | MEDLINE | ID: mdl-29971773

RESUMO

This paper introduces an original application on reconstruction strategies for X-ray computed microtomography, enabling the observation of time-dependent changes that occur during multiphase flow. In general, by sparsely collecting radiographs, the reconstruction of the object is compromised. Optimizations can be achieved by combining specific characteristics of the dynamics with the acquisition. Herein, the proposed method relies on short random intervals in which no drastic changes occur in the sample to acquire as many radiographs as possible that constitute a reconstructible data set. As these intervals are unpredictable, the method tries to guarantee that the collected radiograph data during these specific intervals are enough to recover useful information about the dynamics. Simulations of a percolating fluid in a digital rock are used to replicate an X-ray computed microtomography experiment to test the proposed method. The results demonstrate the potential of the proposed strategy for imaging multiphase flow in porous media and how data collected during distinct events can be combined to enhance the reconstruction of frames of the percolation process.

19.
Parkinsonism Relat Disord ; 54: 56-61, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-29705557

RESUMO

BACKGROUND: Limited data suggests that an altered metabolic and cardiorespiratory exercise response may affect exercise performance in individuals with Huntington's disease (HD). There is no clear exploration of the response in individuals at different stages of the disease or in relation to genetic markers. This study aimed to examine the exercise response and recovery of HD participants, and the relationship to genetic and clinical markers. METHOD: HD gene-positive participants (n = 31; 9 pre-manifest; 22 manifest HD) and a healthy control group (n = 29) performed an incremental exercise test until exhaustion. Performance, cardiorespiratory, metabolic and perceptual responses to exercise were determined from a maximal cycle ergometer test throughout the exercise test and during a recovery period. RESULTS: During sub-maximal exercise, metabolic (lactate levels, oxygen uptake) and cardiorespiratory markers (heart rate) were elevated in HD participants compared to controls. Lactate elevation was specific to pre-manifest HD participants. Work capacity was reduced in both pre-manifest and manifest HD participants with tests terminated with no difference in metabolic, perceptual or cardiorespiratory markers. Submaximal oxygen uptake was correlated with motor score, whilst peak measures were unrelated to genetic or clinical markers. Heart rate recovery was attenuated in pre-manifest and manifest HD participants. CONCLUSIONS: Our findings confirm metabolic and cardiorespiratory deficits reduce exercise performance and affect recovery from an early stage in HD, with submaximal deficits related to phenotypic expression. Exercise capacity appears to be limited by an altered movement economy, thus clinicians should consider an altered exercise response and recovery may affect prescription in HD.


Assuntos
Exercício Físico/fisiologia , Frequência Cardíaca/fisiologia , Doença de Huntington/metabolismo , Doença de Huntington/fisiopatologia , Ácido Láctico/sangue , Consumo de Oxigênio/fisiologia , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
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