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BACKGROUND: After a first-ever seizure, 6 months of seizure freedom is usually required before returning to driving a private motor vehicle, after which the annual risk of seizure recurrence has fallen to ≤20%. Stricter criteria apply for commercial driver's licence (CDL) holders, and a longer period of seizure freedom sufficient for the annual risk of recurrence to be <2% is recommended. However, CDL guidelines are based on little data with few studies having long-term follow-up. METHODS: 1714 patients with first-ever seizures were prospectively studied. Seizure recurrence was evaluated using survival analysis. The annual conditional risk of seizure recurrence was calculated for patients with first-ever unprovoked and acute symptomatic seizures, and according to the presence or absence of clinical, electroencephalogram (EEG) and neuroimaging risk factors for recurrence. RESULTS: The annual risk of recurrence for unprovoked first seizures did not fall below 2% until after 9 years of seizure freedom. The annual risk after 5 years of seizure freedom was still 3.9% (95% CI 1.8% to 6.1%) including for those without epileptiform abnormalities on EEG and with normal imaging. For acute symptomatic first seizures, the annual recurrence risk was 4.5% (95% CI 2.3% to 6.7%) after 1 year and fell below 2% only after 4 years of seizure freedom. CONCLUSIONS: For unprovoked and acute symptomatic first-ever seizure and CDL, a higher-than-expected annual seizure risk persists beyond the currently recommended seizure-free periods, even in those without risk factors for recurrence. Our data can inform decisions regarding a return to driving for CDL holders after first-ever seizure.
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Marine biogenic calcium carbonate (CaCO3) cycles play a key role in ecosystems and in regulating the ocean's ability to absorb atmospheric carbon dioxide (CO2). However, the drivers and magnitude of CaCO3 cycling are not well understood, especially for the upper ocean. Here, we provide global-scale evidence that heterotrophic respiration in settling marine aggregates may produce localized undersaturated microenvironments in which CaCO3 particles rapidly dissolve, producing excess alkalinity in the upper ocean. In the deep ocean, dissolution of CaCO3 is primarily driven by conventional thermodynamics of CaCO3 solubility with reduced fluxes of CaCO3 burial to marine sediments beneath more corrosive North Pacific deep waters. Upper ocean dissolution, shown to be sensitive to ocean export production, can increase the neutralizing capacity for respired CO2 by up to 6% in low-latitude thermocline waters. Without upper ocean dissolution, the ocean might lose 20% more CO2 to the atmosphere through the low-latitude upwelling regions.
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A young man from Pakistan had his first-ever tonic-clonic seizure while playing cricket. Since age 12 years, he had reported involuntary jerks and tremulousness, sometimes with falls, particularly with bright lights. Family history included a brother who developed seizures with myoclonus in his mid-20s and parental consanguinity. Developmental history was normal. Examination identified cognitive impairment with action myoclonus. His clinical presentation raised suspicion of a progressive myoclonus epilepsy. MR scan of the brain showed white matter changes suggesting leucodystrophy with cortical atrophy. Electroencephalogram showed generalised epileptiform abnormalities with photoparoxysmal responses, including at low frequencies (1 Hz). Cortical hyperexcitability was confirmed with giant median somatosensory evoked potentials and long loop reflexes at rest. Multichannel electromyography showed action myoclonus with variable synchronous and asynchronous agonist and antagonist muscle activation with short-burst duration of 25-75 ms, and jerk-locked back-averaging showed premyoclonic potentials consistent with cortical myoclonus. Genetic sequencing identified a homozygous missense variant in the CLN6 gene (c.768C>G p.(Asp256Glu), confirming Kufs disease type A.
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Epilepsias Mioclônicas Progressivas , Mioclonia , Lipofuscinoses Ceroides Neuronais , Masculino , Adulto , Humanos , Criança , Encéfalo , Eletroencefalografia , Convulsões , Eletromiografia , Proteínas de MembranaRESUMO
OBJECTIVE: In Australia, 30% of newly diagnosed epilepsy patients were not immediately treated at diagnosis. We explored health outcomes between patients receiving immediate, deferred, or no treatment, and compared them to the general population. METHODS: Adults with newly diagnosed epilepsy in Western Australia between 1999 and 2016 were linked with statewide health care data collections. Health care utilization, comorbidity, and mortality at up to 10 years postdiagnosis were compared between patients receiving immediate, deferred, and no treatment, as well as with age- and sex-matched population controls. RESULTS: Of 603 epilepsy patients (61% male, median age = 40 years) were included, 422 (70%) were treated immediately at diagnosis, 110 (18%) received deferred treatment, and 71 (12%) were untreated at the end of follow-up (median = 6.8 years). Immediately treated patients had a higher 10-year rate of all-cause admissions or emergency department presentations than the untreated (incidence rate ratio [IRR] = 2.0, 95% confidence interval [CI] = 1.4-2.9) and deferred treatment groups (IRR = 1.7, 95% CI = 1.0-2.8). They had similar 10-year risks of mortality and developing new physical and psychiatric comorbidities compared with the deferred and untreated groups. Compared to population controls, epilepsy patients had higher 10-year mortality (hazard ratio = 2.6, 95% CI = 2.1-3.3), hospital admissions (IRR = 2.3, 95% CI = 1.6-3.3), and psychiatric outpatient visits (IRR = 3.2, 95% CI = 1.6-6.3). Patients with epilepsy were also 2.5 (95% CI = 2.1-3.1) and 3.9 (95% CI = 2.6-5.8) times more likely to develop a new physical and psychiatric comorbidity, respectively. SIGNIFICANCE: Newly diagnosed epilepsy patients with deferred or no treatment did not have worse outcomes than those immediately treated. Instead, immediately treated patients had greater health care utilization, likely reflecting more severe underlying epilepsy etiology. Our findings emphasize the importance of individualizing epilepsy treatment and recognition and management of the significant comorbidities, particularly psychiatric, that ensue following a diagnosis of epilepsy.
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Epilepsia , Adulto , Humanos , Masculino , Feminino , Epilepsia/epidemiologia , Epilepsia/terapia , Epilepsia/diagnóstico , Comorbidade , Hospitalização , Incidência , Modelos de Riscos Proporcionais , Estudos RetrospectivosRESUMO
Contemplative interventions designed to cultivate compassion are receiving increasing empirical attention. Accumulating evidence suggests that these interventions bolster prosocial motivation and warmth towards others. Less is known about how these practices impact compassion in everyday life. Here we consider one mechanistic pathway through which compassion practices may impact perception and action in the world: simulation. Evidence suggests that vividly imagining a situation simulates that experience in the brain as if it were, to a degree, actually happening. Thus, we hypothesize that simulation during imagery-based contemplative practices can construct sensorimotor patterns in the brain that prime an individual to act compassionately in the world. We first present evidence across multiple literatures in Psychology that motivates this hypothesis, including the neuroscience of mental imagery and the emerging literature on prosocial episodic simulation. Then, we examine the specific contemplative practices in compassion-based interventions that may construct such simulations. We conclude with future directions for investigating how compassion-based interventions may shape prosocial perception and action in everyday life.
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OBJECTIVES: Patients with a first-ever unprovoked seizure commonly have subsequent seizures and identifying predictors of recurrence has important management implications. Both prior brain insult and epileptiform abnormalities on electroencephalography (EEG) are established predictors of seizure recurrence. Some studies suggest that a first-ever seizure from sleep has a higher likelihood of recurrence. However, with relatively small numbers and inconsistent definitions, more data are required. METHODS: Prospective cohort study of adults with first-ever unprovoked seizure seen by a hospital-based first seizure service between 2000 and 2015. Clinical features and outcomes of first-ever seizure from sleep and while awake were compared. RESULTS: First-ever unprovoked seizure occurred during sleep in 298 of 1312 patients (23%), in whom the 1-year cumulative risk of recurrence was 56.9% (95% confidence interval [CI] 51.3-62.6) compared to 44.2% (95% CI 41.1-47.3, p < .0001) for patients with first-ever seizure while awake. First-ever seizure from sleep was an independent predictor of seizure recurrence, with a hazard ratio [HR] of 1.44 (95% CI 1.23-1.69), similar to epileptiform abnormalities on EEG (HR 1.48, 95% CI 1.24-1.76) and remote symptomatic etiology (HR 1.47, 95% CI 1.27-1.71). HR for recurrence in patients without either epileptiform abnormalities or remote symptomatic etiology was 1.97 (95% CI 1.60-2.44) for a sleep seizure compared to an awake seizure. For first seizure from sleep, 76% of second seizures also arose from sleep (p < .0001), with 65% of third seizures (p < .0001) also from sleep. Seizures from sleep were less likely to be associated with injury other than orolingual trauma, both with the presenting seizure (9.4% vs 30.6%, p < .0001) and first recurrence (7.5% vs 16.3%, p = .001). SIGNIFICANCE: First-ever unprovoked seizures from sleep are more likely to recur, independent of other risk factors, with recurrences also usually from sleep, and with a lower risk of seizure-related injury. These findings may inform treatment decisions and counseling after first-ever seizure.
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Convulsões , Sono , Adulto , Humanos , Estudos Prospectivos , Recidiva , Convulsões/diagnóstico , Convulsões/epidemiologia , Convulsões/etiologia , Fatores de Risco , Prognóstico , Eletroencefalografia/efeitos adversosRESUMO
OBJECTIVE: Although increased mortality associated with epilepsy is well understood, data in patients after their first-ever seizure are limited. We aimed to assess mortality after a first-ever unprovoked seizure and identify causes of death (CODs) and risk factors. METHODS: A prospective cohort study was undertaken of patients with first-ever unprovoked seizure between 1999 and 2015 in Western Australia. Two age-, gender-, and calendar year-matched local controls were obtained for each patient. Mortality data, including COD, based on International Statistical Classification of Diseases and Related Health Problems, 10th Revision codes, were obtained. Final analysis was performed in January 2022. RESULTS: One thousand two hundred seventy-eight patients with a first-ever unprovoked seizure were compared to 2556 controls. Mean follow-up was 7.3 years (range = .1-20). Overall hazard ratio (HR) for death after a first unprovoked seizure compared to controls was 3.06 (95% confidence interval [CI] = 2.48-3.79), with HRs of 3.30 (95% CI = 2.26-4.82) for those without seizure recurrence and 3.21 (95% CI = 2.47-4.16) after a second seizure. Mortality was also increased in patients with normal imaging and no identified cause (HR = 2.50, 95% CI = 1.82-3.42). Multivariate predictors of mortality were increasing age, remote symptomatic causes, first seizure presentation with seizure cluster or status epilepticus, neurological disability, and antidepressant use at time of first seizure. Seizure recurrence did not influence mortality rate. The commonest CODs were neurological, most relating to the underlying cause of seizures rather than being seizure-related. Substance overdoses and suicide were more frequent CODs in patients compared to controls and were commoner than seizure-related deaths. SIGNIFICANCE: Mortality is increased two- to threefold after a first-ever unprovoked seizure, independent of seizure recurrence, and is not only attributable to the underlying neurological etiology. The greater likelihood of deaths related to substance overdose and suicide highlights the importance of assessing psychiatric comorbidity and substance use in patients with first-ever unprovoked seizure.
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Overdose de Drogas , Epilepsia Generalizada , Humanos , Estudos Prospectivos , Convulsões , Causas de Morte , Fatores de Risco , RecidivaRESUMO
Projecting the effects of climate change on net reef calcium carbonate production is critical to understanding the future impacts on ecosystem function, but prior estimates have not included corals' natural adaptive capacity to such change. Here we estimate how the ability of symbionts to evolve tolerance to heat stress, or for coral hosts to shuffle to favourable symbionts, and their combination, may influence responses to the combined impacts of ocean warming and acidification under three representative concentration pathway (RCP) emissions scenarios (RCP2.6, RCP4.5 and RCP8.5). We show that symbiont evolution and shuffling, both individually and when combined, favours persistent positive net reef calcium carbonate production. However, our projections of future net calcium carbonate production (NCCP) under climate change vary both spatially and by RCP. For example, 19%-35% of modelled coral reefs are still projected to have net positive NCCP by 2050 if symbionts can evolve increased thermal tolerance, depending on the RCP. Without symbiont adaptive capacity, the number of coral reefs with positive NCCP drops to 9%-13% by 2050. Accounting for both symbiont evolution and shuffling, we project median positive NCPP of coral reefs will still occur under low greenhouse emissions (RCP2.6) in the Indian Ocean, and even under moderate emissions (RCP4.5) in the Pacific Ocean. However, adaptive capacity will be insufficient to halt the transition of coral reefs globally into erosion by 2050 under severe emissions scenarios (RCP8.5).
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Antozoários , Recifes de Corais , Animais , Antozoários/fisiologia , Ecossistema , Mudança Climática , Carbonato de CálcioRESUMO
OBJECTIVE: This study explores whether variability in the implementation of an undergraduate course on human flourishing is differentially associated with student outcomes. PARTICIPANTS: 101 students in the "Art and Science of Human Flourishing" course across three large, public, R1 universities in Fall 2018 participated in the study. METHODS: Formative course data included researcher observations of weekly class pedagogy, students' weekly meditation practice logs and end-of-course assessments, and pre/post surveys measuring changes in participating students' outcomes related to flourishing (e.g., attentional skills, social-emotional skills, perspectives on flourishing, mental and physical health). RESULTS: Although course pedagogy and student engagement varied across the three universities, students' outcomes were nonetheless similar. CONCLUSIONS: Variability in course implementation did not appear to differentially affect students' outcomes. We tentatively conclude that other institutions interested in offering the flourishing course may make limited adaptations to fit their pedagogical preferences without concern for altering its impact on students.
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Meditação , Estudantes , Humanos , Estudantes/psicologia , Universidades , Emoções , Inquéritos e QuestionáriosRESUMO
Objectives: Significant concerns have been raised about the "mental health crisis" on college campuses, with attention turning to what colleges can do beyond counseling services to address students' mental health and well-being. We examined whether primarily first-year (89.1%) undergraduate students (n=651) who enrolled in the Art and Science of Human Flourishing (ASHF), a novel academic and experiential for-credit elective course on human flourishing, would demonstrate improved mental health and strengthen skills, perspectives, and behaviors associated with flourishing relative to students who did not enroll in this course. Methods: In a two-wave, multi-site, propensity-score matched controlled trial (ASHF n=217, Control n=434; N=651), we used hierarchal linear models and false discovery rate corrected doubly robust estimates to evaluate the impact of the ASHF on attention and social-emotional skill development, flourishing perspectives, mental health, health, and risk behavior outcomes. Results: ASHF participants reported significantly improved mental health (i.e., reduced depression) and flourishing, improvements on multiple attention and social-emotional skills (e.g., attention function, self-compassion), and increases in prosocial attitudes (empathic concern, shared humanity; Cohen's ds= 0.18-0.46) compared to controls. There was no evidence for ASHF course impacts on health or risk behaviors, raising the possibility that these outcomes take more time to change. Conclusions: This research provides initial evidence that the ASHF course may be a promising curricular approach to reduce and potentially prevent poor mental health while promoting flourishing in college students. Continued research is needed to confirm these conclusions.
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OBJECTIVE: Patients with epilepsy not uncommonly self-discontinue treatment with antiseizure medications (ASM). The rate, reasons for this, and consequences have not been well studied. METHODS: We analyzed self-discontinuation of ASM treatment in patients with recently diagnosed epilepsy via review of clinic letters and hospital correspondence in a prospective cohort of first seizure patients. RESULTS: We studied 489 patients with newly diagnosed and treated epilepsy (median age 41, range 14-88, 62% male), followed up for a median duration of 3.0â¯years (interquartile range [IQR]: 1.2-6.0). Seventy eight (16.0%) self-discontinued ASM therapy after a median treatment duration of 1.4â¯years (IQR: 0.4-2.9), and after a median duration of seizure freedom of 11.8â¯months (IQR: 4.6-31.8). Patients commonly self-discontinued treatment due to adverse effects (41%), perception that treatment was no longer required (35%), and planned or current pregnancy (12%). Patients who self-discontinued were less likely to have epileptogenic lesions on neuroimaging (hazard ratio [HR]â¯=â¯0.44, 95% confidence interval [CI]: 0.23-0.83), presentation with seizure clusters (HRâ¯=â¯0.32, 95% CI: 0.14-0.69) and presentation with tonic-clonic seizures (HRâ¯=â¯0.36, 95% CI: 0.19-0.70). Patients with shorter interval since the last seizure (HRâ¯=â¯0.76, 95% CI: 0.66-0.86) were more likely to self-discontinue treatment. Sleep deprivation prior to seizures before diagnosis (HRâ¯=â¯1.80, 95% CI: 1.05-3.09) and significant alcohol or illicit drug use (HRâ¯=â¯2.35, 95% CI: 1.20-4.59) were also associated with higher rates of discontinuation. After discontinuation, 51 patients (65%) experienced seizure recurrence, and 43 (84%) restarted treatment. Twenty two patients (28%) experienced a seizure-related injury after treatment discontinuation. SIGNIFICANCE: Self-initiated discontinuation of ASM treatment was not uncommon in patients with newly treated epilepsy. Reasons for discontinuation highlight areas for improved discussion with patients, including the chronicity of epilepsy and management strategies for current or potential adverse effects.
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Anticonvulsivantes , Epilepsia , Adulto , Anticonvulsivantes/uso terapêutico , Epilepsia/induzido quimicamente , Epilepsia/tratamento farmacológico , Feminino , Humanos , Masculino , Estudos Prospectivos , Fatores de Risco , Convulsões/induzido quimicamente , Convulsões/tratamento farmacológicoRESUMO
BACKGROUND AND OBJECTIVES: Our aim was to study the development of pure sleep epilepsy after a first-ever seizure from sleep in adults. METHODS: This was a prospective observational study of patients seen at a tertiary hospital-based first seizure clinic between 2000 and 2011. Adults with a first-ever unprovoked seizure from sleep were consecutively recruited. All patients were followed up at least once after the initial seizure, and those not requiring regular clinical review were contacted every 1 to 2 years. The timing and pattern of subsequent seizures and potential predictors of future awake seizures were analyzed. RESULTS: Two hundred thirty-nine adults with a first-ever unprovoked seizure from sleep were identified. Sixty-one percent were male; mean age was 43 years (range 14-88 years); and median follow-up of 8.8 years (range 2 months-18 years). Of the 174 patients who had recurrent seizures, 130 patients (75%) had their second seizure from sleep, and of these, 76 of 94 (81%) also had their third seizure from sleep. Eighty-nine patients (37%) developed awake seizures during follow-up. In half of these patients, the awake seizure occurred within 2 years of the initial seizure. The risk of an awake seizure within 1 year of a first-ever seizure from sleep was 13.9% (95% CI 9.4%-18.3%), falling to 2.0% to 5.3% per year after 3 years. The risks of an awake seizure within 1 year of a second or third consecutive sleep seizure were 9.9% (95% CI 4.6%-15.3%) and 8.7% (95% CI 2.0%-15.4%), respectively, and similarly decreased with time. DISCUSSION: Most initial seizure recurrences after a first-ever sleep seizure occur during sleep. While more than one-third eventually had awake seizures, the annual risk of an awake seizure was ≤14% and decreased with time, albeit with a small ongoing risk of between 2% and 5% per year. These findings may be used in counseling patients with seizures from sleep and to inform driving recommendations.
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Epilepsia Reflexa , Narcolepsia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Estudos de Coortes , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Recidiva , Convulsões/epidemiologia , Sono , Adulto JovemRESUMO
Projections of climate change impacts on marine ecosystems have revealed long-term declines in global marine animal biomass and unevenly distributed impacts on fisheries. Here we apply an enhanced suite of global marine ecosystem models from the Fisheries and Marine Ecosystem Model Intercomparison Project (Fish-MIP), forced by new-generation Earth system model outputs from Phase 6 of the Coupled Model Intercomparison Project (CMIP6), to provide insights into how projected climate change will affect future ocean ecosystems. Compared with the previous generation CMIP5-forced Fish-MIP ensemble, the new ensemble ecosystem simulations show a greater decline in mean global ocean animal biomass under both strong-mitigation and high-emissions scenarios due to elevated warming, despite greater uncertainty in net primary production in the high-emissions scenario. Regional shifts in the direction of biomass changes highlight the continued and urgent need to reduce uncertainty in the projected responses of marine ecosystems to climate change to help support adaptation planning.
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OBJECTIVES: To compare the outcomes between immediate and deferred treatments in patients diagnosed after one or multiple (two or more) seizures. METHODS: Our observational study investigated seizure recurrence and 12-month seizure remission in patients with newly diagnosed epilepsy, comparing immediate to deferred treatment in patients diagnosed after one seizure or after two or more seizures. RESULTS: Of 598 patients (62% male, median age 39â¯years), 347 (58%) were treated at diagnosis and 251 (42%) received deferred or no treatment. Seizure recurrence was higher with deferred treatment both in patients diagnosed after two or more seizures (nâ¯=â¯363; adjusted hazard ratio [aHR]â¯=â¯2.38, 95% confidence interval [CI]: 1.79-3.14, pâ¯<â¯0.001) and after one seizure (nâ¯=â¯235; aHRâ¯=â¯1.41, 95% CI: 0.995-1.99, pâ¯=â¯0.05). Cumulative seizure recurrence rates at two years in patients diagnosed after two or more seizures were 73% with deferred treatment and 49% with immediate treatment (risk-factor-corrected number-needed-to-treat [NNT]â¯=â¯4), and in those diagnosed after one seizure the rates were 60% and 51% (NNTâ¯=â¯8). Of 380 patients with eligible follow-up (median 4.3â¯years), 287 (76%) had been in seizure remission for at least one year and 211 (56%) remained in remission at last follow-up. Long-term remission rates were similar between immediate and deferred treatments, and between patients diagnosed after one seizure and those with two or more seizures. SIGNIFICANCE: Immediate rather than deferred treatment was less likely to influence seizure recurrence in patients diagnosed with epilepsy after a single seizure than in those diagnosed after two or more seizures, and showed no differences in long-term seizure freedom.
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Epilepsia , Tempo para o Tratamento , Adulto , Anticonvulsivantes/uso terapêutico , Epilepsia/tratamento farmacológico , Epilepsia/terapia , Feminino , Humanos , Masculino , Recidiva , Convulsões/tratamento farmacológico , Convulsões/terapiaRESUMO
An emerging focus in affective science is the expertise that underlies healthy emotionality. A growing literature highlights emotional granularity - the ability to make fine-grained distinctions in one's affective feelings - as an important skill. Cross-sectional evidence indicating the benefits of emotional granularity raises the question of how emotional granularity might be intentionally cultivated through training. To address this question, we present shared theoretical features of centuries-old Buddhist philosophy and modern constructionist theory that motivate the hypothesis that contemplative practices may improve granularity. We then examine the specific mindfulness-style practices originating in Buddhist traditions that are hypothesized to bolster granularity. We conclude with future directions to empirically test whether emotional granularity can be intentionally cultivated.
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OBJECTIVES: Randomized studies in drug-resistant epilepsy (DRE) typically involve addition of a new anti-seizure medication (ASM). However, in clinical practice, if the patient is already taking multiple ASMs, then substitution of one of the current ASMs commonly occurs, despite little evidence supporting this approach. METHODS: Longitudinal prospective study of seizure outcome after commencing a previously untried ASM in patients with DRE. Multivariable time-to-event and logistic regression models were used to evaluate outcomes by whether the new ASM was introduced by addition or substitution. RESULTS: A total of 816 ASM changes in 436 adult patients with DRE between 2010 and 2018 were analyzed. The new ASM was added on 407 (50.1%) occasions and substituted on 409 (49.9%). Mean patient follow-up was 3.2 years. Substitution was more likely if the new ASM was enzyme-inducing or in patients with a greater number of concurrent ASMs. ASM add-on was more likely if a γ-aminobutyric acid (GABA) agonist was introduced or if the patient had previously trialed a higher number of ASMs. The rate of discontinuation due to lack of tolerability was similar between the add-on and substitution groups. No difference between the add-on and substitution ASM introduction strategies was observed for the primary outcome of ≥50% seizure reduction at 12 months. SIGNIFICANCE: Adding or substituting a new ASM in DRE has the same influence on seizure outcomes. The findings confirm that ASM alterations in DRE can be individualized according to concurrent ASM therapy and patient characteristics.
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Anticonvulsivantes/uso terapêutico , Epilepsia Resistente a Medicamentos/tratamento farmacológico , Substituição de Medicamentos/estatística & dados numéricos , Quimioterapia Combinada/estatística & dados numéricos , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Modelos Logísticos , Estudos Longitudinais , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Adulto JovemRESUMO
Anthropogenically forced changes in ocean biogeochemistry are underway and critical for the ocean carbon sink and marine habitat. Detecting such changes in ocean biogeochemistry will require quantification of the magnitude of the change (anthropogenic signal) and the natural variability inherent to the climate system (noise). Here we use Large Ensemble (LE) experiments from four Earth system models (ESMs) with multiple emissions scenarios to estimate Time of Emergence (ToE) and partition projection uncertainty for anthropogenic signals in five biogeochemically important upper-ocean variables. We find ToEs are robust across ESMs for sea surface temperature and the invasion of anthropogenic carbon; emergence time scales are 20-30 yr. For the biological carbon pump, and sea surface chlorophyll and salinity, emergence time scales are longer (50+ yr), less robust across the ESMs, and more sensitive to the forcing scenario considered. We find internal variability uncertainty, and model differences in the internal variability uncertainty, can be consequential sources of uncertainty for projecting regional changes in ocean biogeochemistry over the coming decades. In combining structural, scenario, and internal variability uncertainty, this study represents the most comprehensive characterization of biogeochemical emergence time scales and uncertainty to date. Our findings delineate critical spatial and duration requirements for marine observing systems to robustly detect anthropogenic change.
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Purpose of Review: The changes or updates in ocean biogeochemistry component have been mapped between CMIP5 and CMIP6 model versions, and an assessment made of how far these have led to improvements in the simulated mean state of marine biogeochemical models within the current generation of Earth system models (ESMs). Recent Findings: The representation of marine biogeochemistry has progressed within the current generation of Earth system models. However, it remains difficult to identify which model updates are responsible for a given improvement. In addition, the full potential of marine biogeochemistry in terms of Earth system interactions and climate feedback remains poorly examined in the current generation of Earth system models. Summary: Increasing availability of ocean biogeochemical data, as well as an improved understanding of the underlying processes, allows advances in the marine biogeochemical components of the current generation of ESMs. The present study scrutinizes the extent to which marine biogeochemistry components of ESMs have progressed between the 5th and the 6th phases of the Coupled Model Intercomparison Project (CMIP).
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An amendment to this paper has been published and can be accessed via a link at the top of the paper.
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Marine microbes form the base of ocean food webs and drive ocean biogeochemical cycling. Yet little is known about the ability of microbial populations to adapt as they are advected through changing conditions. Here, we investigated the interplay between physical and biological timescales using a model of adaptation and an eddy-resolving ocean circulation climate model. Two criteria were identified that relate the timing and nature of adaptation to the ratio of physical to biological timescales. Genetic adaptation was impeded in highly variable regimes by nongenetic modifications but was promoted in more stable environments. An evolutionary trade-off emerged where greater short-term nongenetic transgenerational effects (low-γ strategy) enabled rapid responses to environmental fluctuations but delayed genetic adaptation, while fewer short-term transgenerational effects (high-γ strategy) allowed faster genetic adaptation but inhibited short-term responses. Our results demonstrate that the selective pressures for organisms within a single water mass vary based on differences in generation timescales resulting in different evolutionary strategies being favored. Organisms that experience more variable environments should favor a low-γ strategy. Furthermore, faster cell division rates should be a key factor in genetic adaptation in a changing ocean. Understanding and quantifying the relationship between evolutionary and physical timescales is critical for robust predictions of future microbial dynamics.