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1.
Br J Gen Pract ; 74(suppl 1)2024 Jun 20.
Artículo en Inglés | MEDLINE | ID: mdl-38902076

RESUMEN

BACKGROUND: Obesity is a driver of multimorbidity. Knowledge regarding individual and population based solutions is evolving in primary care. Stigma/self-stigma are important in developing clinical solutions. Inquiry based stress reduction (IBSR) is emerging as a solution for self-stigma in a range of conditions. This study explores IBSR (also known as The Work of Byron Katie) in obesity self-stigma in the GP setting, with severe obesity, utilising a multidisciplinary approach. AIM: Is it feasible/acceptable to utilise Inquiry Based Stress Reduction in the GP setting for obesity? METHOD: Mixed-method pilot study including a convenience sample of people with severe spectrum obesity from a three-doctor general practice, including use of IBSR provided in both group, partner and individual settings, predominantly online, utilising certified and accredited IBSR facilitators, a clinical psychologist, and participating GPs. Outcomes include pre- and post-intervention surveys (Becks Depression Scale, HRQoL, Weight Bias Internalisation Scale, Weight Self-stigma Questionnaire) and qualitative data from participants. RESULTS: Of 22 initially invited to participate, 14 commenced and 10 completed the intervention. Mean BMI was 42.8, mean age 49 years, female:male = 7:3. Many believed obesity was their own fault, related very difficult interactions with healthcare professionals, and valued opportunity to engage with the intervention. While participants had alarming levels of comorbidity, they were far more concerned regarding stigma and self-stigma. CONCLUSION: Results and experience in practice indicate this approach is feasible and acceptable. Results are valuable in planning a larger study in multiple practices.


Asunto(s)
Medicina General , Estigma Social , Estrés Psicológico , Humanos , Femenino , Masculino , Persona de Mediana Edad , Proyectos Piloto , Adulto , Obesidad Mórbida/psicología , Autoimagen , Encuestas y Cuestionarios
2.
Artículo en Inglés | MEDLINE | ID: mdl-38884031

RESUMEN

During the pandemic, many older adults felt 'out of place' in their home, work, and community spaces with potentially long-term consequences for health and wellbeing. Using national data from the COVID-19 Coping Study, thematic analysis of online long-answer responses (n = 1171; mean age 68 years; 71% female; 93% non-Hispanic White; 86% with at least a 4-year college degree; data collected April-June 2022) identified four themes regarding why particular places are challenging since the pandemic onset: (1) viral exposure fears, (2) frustrating regulations, (3) uncomfortable and hostile social dynamics, and (4) 'out of place' negative emotions. Participants also shared how they continuously address or adapt to place-based challenges through lifestyle adjustments and coping strategies. Novel findings may inform multi-scalar policymaking and interventions to support wellbeing in later life in times of stress and instability.

3.
Artículo en Inglés | MEDLINE | ID: mdl-38887431

RESUMEN

Little is known about longer-term changes to community participation since the COVID-19 pandemic onset and potential implications for health and wellbeing in later life. This multi-method investigation analyzes national data from the COVID-19 Coping Study. Statistical analyses of survey data (n = 1,630; mean age 67.9 years; data collected April/May 2022) identified that adults residing in the US still tended to stay inside their homes more often since the pandemic onset. Overall, participants decreased their engagement with amenities such as eateries, gyms, and arts and cultural sites. Reflexive thematic analysis of semi-structured in-depth interviews (n = 57; mean age 70.7 years; data collected May-July 2021) identified altered community participation with perceived long-term impacts on physical, mental, and social health and wellbeing. The results provide novel insights about the critical nature of 'third places' to support later life, and policy implications to strengthen community environments. Investment in outdoor, well-ventilated, and distanced third places may support wellbeing.

4.
J Synchrotron Radiat ; 31(Pt 2): 409-419, 2024 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-38363224

RESUMEN

The direction of particle accelerator development is ever-increasing beam quality, currents and repetition rates. This poses a challenge to traditional diagnostics that directly intercept the beam due to the mutual destruction of both the beam and the diagnostic. An alternative approach is to infer beam parameters non-invasively from the synchrotron radiation emitted in bending magnets. However, inferring the beam distribution from a measured radiation pattern is a complex and computationally expensive task. To address this challenge we present SYRIPY (SYnchrotron Radiation In PYthon), a software package intended as a tool for performing inference of synchrotron-radiation-based diagnostics. SYRIPY has been developed using PyTorch, which makes it both differentiable and able to leverage the high performance of GPUs, two vital characteristics for performing statistical inference. The package consists of three modules: a particle tracker, Lienard-Wiechert solver and Fourier optics propagator, allowing start-to-end simulation of synchrotron radiation detection to be carried out. SYRIPY has been benchmarked against SRW, the prevalent numerical package in the field, showing good agreement and up to a 50× speed improvement. Finally, we have demonstrated how SYRIPY can be used to perform Bayesian inference of beam parameters using stochastic variational inference.

5.
Artículo en Inglés | MEDLINE | ID: mdl-38284333

RESUMEN

OBJECTIVES: Identifying social policies that can promote cognitive health is crucial for reducing the global burden of dementia. We evaluated the importance of educational attainment for later-life cognitive function in various social and geographic settings. METHODS: Using harmonized data for individuals aged ≥65 years from the United States Health and Retirement Study (HRS) and its international partner studies in England, Mexico, China, and India, and each study's respective Harmonized Cognitive Assessment Protocol (HCAP), we conducted a cross-national comparative study to examine the role of educational attainment in later-life cognitive function across countries (n = 14,980, 2016-2019). We used multivariable-adjusted regression to estimate associations between educational attainment and harmonized global cognitive function scores. RESULTS: In Mexico, China, and India, the general cognitive function scores on average are approximately one standard deviation of the HRS-HCAP cognitive function score distribution lower compared to the United States and England, paralleling patterns of educational attainment across countries. In all countries, higher educational attainment was associated with progressively higher later-life cognitive function scores. Population-level differences in educational attainment explained about 50%-90% of the observed differences in cognitive function scores across countries. DISCUSSION: The relationship between education and later-life cognitive function across social and geographic contexts underscores the crucial role of education to promote cognitive health and reduce dementia risk. Continual improvement of educational attainment in low- and middle-income settings may yield a significant pay-off in later-life cognitive health.


Asunto(s)
Éxito Académico , Demencia , Humanos , Estados Unidos/epidemiología , Países en Desarrollo , Escolaridad , Cognición , Demencia/diagnóstico
6.
Alzheimers Dement ; 20(3): 1933-1943, 2024 03.
Artículo en Inglés | MEDLINE | ID: mdl-38159252

RESUMEN

INTRODUCTION: We conducted a cross-national comparison of the association between main lifetime occupational skills and later-life cognitive function across four economically and socially distinct countries. METHODS: Data were from population-based studies of aging and their Harmonized Cognitive Assessment Protocols (HCAPs) in the US, South Africa, India, and Mexico (N = 10,037; Age range: 50 to 105 years; 2016 to 2020). Main lifetime occupational skill was classified according to the International Standard Classification of Occupations. Weighted, adjusted regression models estimated pooled and country-specific associations between main lifetime occupational skill and later-life general cognitive function in men and women. RESULTS: We observed positive gradients between occupational skill and later-life cognitive function for men and women in the US and Mexico, a positive gradient for women but not men in India, and no association for men or women in South Africa. DISCUSSION: Main lifetime occupations may be a source of later-life cognitive reserve, with cross-national heterogeneity in this association. HIGHLIGHTS: No studies have examined cross-national differences in the association of occupational skill with cognition. We used data from Harmonized Cognitive Assessment Protocols in the US, Mexico, India, and South Africa. The association of occupational skill with cognitive function varies by country and gender.


Asunto(s)
Envejecimiento , Cognición , Masculino , Humanos , Femenino , Estados Unidos/epidemiología , Anciano , Persona de Mediana Edad , Anciano de 80 o más Años , Sudáfrica/epidemiología , México/epidemiología , Envejecimiento/psicología , Ocupaciones
7.
JMIR Perioper Med ; 6: e38462, 2023 Mar 16.
Artículo en Inglés | MEDLINE | ID: mdl-36928105

RESUMEN

BACKGROUND: Hyponatremia and hypernatremia, as conventionally defined (<135 mEq/L and >145 mEq/L, respectively), are associated with increased perioperative morbidity and mortality. However, the effects of subtle deviations in serum sodium concentration within the normal range are not well-characterized. OBJECTIVE: The purpose of this analysis is to determine the association between borderline hyponatremia (135-137 mEq/L) and hypernatremia (143-145 mEq/L) on perioperative morbidity and mortality. METHODS: A retrospective cohort study was performed using data from the American College of Surgeons National Surgical Quality Improvement Program database. This database is a repository of surgical outcome data collected from over 600 hospitals across the United States. The National Surgical Quality Improvement Program database was queried to extract all patients undergoing elective, noncardiac surgery from 2015 to 2019. The primary predictor variable was preoperative serum sodium concentration, measured less than 5 days before the index surgery. The 2 primary outcomes were the odds of morbidity and mortality occurring within 30 days of surgery. The risk of both outcomes in relation to preoperative serum sodium concentration was modeled using weighted generalized additive models to minimize the effect of selection bias while controlling for covariates. RESULTS: In the overall cohort, 1,003,956 of 4,551,726 available patients had a serum sodium concentration drawn within 5 days of their index surgery. The odds of morbidity and mortality across sodium levels of 130-150 mEq/L relative to a sodium level of 140 mEq/L followed a nonnormally distributed U-shaped curve. The mean serum sodium concentration in the study population was 139 mEq/L. All continuous covariates were significantly associated with both morbidity and mortality (P<.001). Preoperative serum sodium concentrations of less than 139 mEq/L and those greater than 144 mEq/L were independently associated with increased morbidity probabilities. Serum sodium concentrations of less than 138 mEq/L and those greater than 142 mEq/L were associated with increased mortality probabilities. Hypernatremia was associated with higher odds of both morbidity and mortality than corresponding degrees of hyponatremia. CONCLUSIONS: Among patients undergoing elective, noncardiac surgery, this retrospective analysis found that preoperative serum sodium levels less than 138 mEq/L and those greater than 142 mEq/L are associated with increased morbidity and mortality, even within currently accepted "normal" ranges. The retrospective nature of this investigation limits the ability to make causal determinations for these findings. Given the U-shaped distribution of risk, past investigations that assume a linear relationship between serum sodium concentration and surgical outcomes may need to be revisited. Likewise, these results question the current definition of perioperative eunatremia, which may require future prospective investigations.

8.
Innov Aging ; 6(5): igac047, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-36035631

RESUMEN

Background and Objectives: This study aimed to examine the associations between multimorbidity at the COVID-19 pandemic onset and subsequent longitudinal trajectories of depressive symptoms, anxiety symptoms, and loneliness in middle-aged and older adults over a 12-month follow-up. Research Design and Methods: Data were from monthly online questionnaires in the COVID-19 Coping Study of U.S. adults aged ≥55 from April/May 2020 through April/May 2021 (N = 4,024). Multimorbidity was defined as having ≥2 versus <2 chronic conditions at baseline. Mental health outcomes were assessed monthly as depressive symptoms (8-item Center for Epidemiologic Studies Depression scale), anxiety symptoms (5-item Beck Anxiety Inventory), and loneliness (3-item UCLA Loneliness Scale). We used multivariable-adjusted population- and attrition-weighted mixed-effects linear models to examine the longitudinal associations between multimorbidity and mental health symptoms. Results: Multimorbidity at the pandemic onset was associated with elevated depressive (b = 0.37; 95% CI: 0.16-0.59) and anxiety (b = 0.39; 95% CI: 0.15-0.62) symptoms at baseline. Changes in symptoms for all three mental health outcomes were nonlinear over time, with worsening symptoms over the first 6 months of the pandemic (April/May to September/October 2020), followed by improvement in symptoms over the subsequent 6 months (September/October 2020 to April/May 2021). Middle-aged and older adults with multimorbidity experienced faster rates of change in anxiety symptoms and loneliness than those without multimorbidity, with persistently elevated mental health symptomatology throughout the follow-up. Discussion and Implications: Results highlight the unique and persistent mental health risks experienced by middle-aged and older adults with multimorbidity during the COVID-19 pandemic. The observed improvements in symptoms underscore the mental resilience of these individuals, indicating their adaptation to the ongoing pandemic.

9.
SSM Ment Health ; 2: 100097, 2022 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-35434675

RESUMEN

Background: The acute impacts of COVID-19-related mental health concerns on cognitive function among middle-aged and older adults are unknown. We investigated whether between-person (BP) differences and within-person (WP) changes in loneliness, anxiety, and worry about COVID-19 were related to cognitive function and abilities in a longitudinal cohort of middle-aged and older United States (US) adults over a nine-month period during the COVID-19 pandemic. Methods: Data were from bimonthly questionnaires in the nationwide COVID-19 Coping Study from August/September 2020 through April/May 2021 (N = 2262 adults aged ≥55). Loneliness was assessed with the 3-item UCLA Loneliness Scale, anxiety with the 5-item Beck Anxiety Inventory, and COVID-19 worry on a 5-point Likert-type scale. Cognitive outcomes were assessed with the 6-item Patient Reported Outcomes Measurement Information System (PROMIS®) Cognitive Function and Abilities scales. Marginal structural models incorporating inverse probability of treatment and attrition weights as well as sampling weights estimated the BP and WP relationships between the mental health predictors and PROMIS® cognitive scores over time. Results: In any given month, experiencing a loneliness or anxiety symptom score higher than the sample mean (BP difference) or higher than one's personal mean across the nine-month period (WP change) was negatively associated with cognitive function and abilities in that month. The observed magnitudes of associations were stronger for BP differences than for WP changes and were the strongest for anxiety symptom scale scores. Conclusions: Elevated loneliness and anxiety symptoms, both relative to other adults and to one's usual levels, were acutely associated with worse perceived cognitive function and abilities over a nine-month period during the COVID-19 pandemic in the United States. The long-term impacts of mental health symptoms experienced during the pandemic for population cognitive health should be explored.

11.
Soc Psychiatry Psychiatr Epidemiol ; 57(6): 1273-1282, 2022 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-35244741

RESUMEN

PURPOSE: We investigated the relationships between physical isolation at home during the period when many US states had shelter-in-place orders and subsequent longitudinal trajectories of depression, anxiety, and loneliness in older adults over a 6 month follow-up. METHODS: Data were from monthly online questionnaires with US adults aged ≥ 55 in the nation-wide COVID-19 Coping Study (April through October 2020, N = 3978). Physical isolation was defined as not leaving home except for essential purposes (0, 1-3, 4-6, and 7 days in the past week), measured at baseline (April-May). Outcomes were depressive symptoms (8-item Center for Epidemiological Studies Depression Scale), anxiety symptoms (5-item Beck Anxiety Inventory), and loneliness (3-item UCLA loneliness scale), measured monthly (April-October). Multivariable, population- and attrition-weighted linear mixed-effects models assessed the relationships between baseline physical isolation with mental health symptoms at baseline and over time. RESULTS: Physical isolation (7 days versus 0 days in the past week) was associated with elevated depressive symptoms (adjusted ß = 0.85; 95% CI 0.10-1.60), anxiety symptoms (adjusted ß = 1.22; 95% CI 0.45-1.98), and loneliness (adjusted ß = 1.06; 95% CI 0.51-1.61) at baseline, but not with meaningful rate of change in these mental health outcomes over time. The symptom burden of each mental health outcome increased with increasing past-week frequency of physical isolation. CONCLUSION: During the early COVID-19 pandemic, physical isolation was associated with elevated depressive symptoms, anxiety symptoms, and loneliness, which persisted over time. These findings highlight the unique and persistent mental health risks of physical isolation at home under pandemic control measures.


Asunto(s)
COVID-19 , Adaptación Psicológica , Adulto , Anciano , Ansiedad/epidemiología , Ansiedad/psicología , COVID-19/epidemiología , Depresión/epidemiología , Humanos , Soledad/psicología , Salud Mental , Persona de Mediana Edad , Pandemias
14.
Public Health Rep ; 136(6): 754-764, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34283657

RESUMEN

OBJECTIVES: Loneliness is associated with increased risks of adverse health outcomes among middle-aged and older adults. We estimated the prevalence of loneliness and identified key sociodemographic, employment, living, and health-related risk factors for loneliness among adults aged ≥55 during the early phase of the COVID-19 pandemic in the United States, when much of the country was under shelter-in-place orders. METHODS: We collected data from online questionnaires in the COVID-19 Coping Study, a national study of 6938 US adults aged ≥55 from April 2 through May 31, 2020. We estimated the population-weighted prevalence of loneliness (scores ≥6 of 9 on the 3-item UCLA Loneliness Scale), overall and by sociodemographic, employment, living, and health-related factors. We used population-weighted modified Poisson regression models to estimate prevalence ratios (PRs) and 95% CIs for the associations between these factors and loneliness, adjusting for age, sex, race, ethnicity, and education level. RESULTS: Overall, we estimated that 29.5% (95% CI, 27.9%31.3%) of US adults aged ≥55 were considered high in loneliness in April and May 2020. In population-weighted adjusted models, loneliness was the most prevalent among those who reported depression, who were not married or in a relationship, who lived alone, and who were unemployed at the onset of the pandemic. CONCLUSIONS: We identified subpopulations of middle-aged and older adults who were vulnerable to loneliness during a period when COVID-19 shelter-in-place orders were in place across most of the country. These insights may inform the allocation of resources to mitigate an unintended health consequence during times of restricted activity.


Asunto(s)
COVID-19/epidemiología , Soledad/psicología , Aislamiento Social/psicología , Adaptación Psicológica , Anciano , Anciano de 80 o más Años , COVID-19/psicología , Control de Enfermedades Transmisibles/métodos , Depresión/epidemiología , Femenino , Estado de Salud , Humanos , Masculino , Persona de Mediana Edad , Pandemias , SARS-CoV-2 , Factores Socioeconómicos , Estados Unidos/epidemiología
15.
Front Public Health ; 9: 643807, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33898379

RESUMEN

Objective: Older adults may struggle with stresses and daily life challenges associated with the Coronavirus Disease 2019 (COVID-19) pandemic. Yet they may also utilize emotional and behavioral coping strategies. This qualitative paper aims to identify ways of coping with worries and stress during the pandemic from the perspectives of older adults in the United States. Methods: The COVID-19 Coping Study recruited 6,938 adults aged ≥55 through online multi-frame sampling from April 2-May 31, 2020 across all 50 US states, the District of Columbia, and Puerto Rico. The online questionnaire focused on the effects of COVID-19 on daily life, mental health, and well-being. This included an open-ended question regarding participants' coping strategies. We used qualitative content analysis to identify and code diverse coping strategies. Our general inductive approach enabled findings to emerge from the most frequent and dominant themes in the raw data. Results: A total of 5,180 adults [74% of the total sample; mean age 67.3 (SD 7.9); 63.8% female] responded to the question about using strategies to cope with living through the COVID-19 pandemic. Frequently-reported strategies included exercising and going outdoors, modifying routines, following public health guidelines, adjusting attitudes, and staying socially connected. Some coping strategies were health-limiting (e.g., overeating), while most strategies encouraged self-improvement, positive adjustment, and wellness. Conclusions: This study provides novel qualitative evidence on coping strategies of older adults early in the COVID-19 pandemic. Findings can inform community and clinical interventions to support older adults that harness positive coping strategies such as exercise, modified routines, and social strategies to improve physical and mental health, foster social support, and encourage meaningful daily activities during times of stress and trauma.


Asunto(s)
Adaptación Psicológica , COVID-19/psicología , Pandemias , Anciano , District of Columbia , Femenino , Humanos , Masculino , Persona de Mediana Edad , Puerto Rico , Encuestas y Cuestionarios , Estados Unidos/epidemiología
16.
Am J Epidemiol ; 190(7): 1294-1305, 2021 07 01.
Artículo en Inglés | MEDLINE | ID: mdl-33534903

RESUMEN

Evidence on the role of early-life adversity in later-life memory decline is conflicting. We investigated the relationships between adverse childhood experiences (ACEs) and memory performance and rate of decline over a 10-year follow-up among middle-aged and older adults in England. Data were from biennial interviews with 5,223 participants aged 54 years or older in the population-representative English Longitudinal Study of Ageing from 2006/2007 to 2016/2017. We examined self-reports of 9 ACEs prior to age 16 years that related to abuse, household dysfunction, and separation from family. Memory was assessed at each time point as immediate and delayed recall of 10 words. Using linear mixed-effects models with person-specific random intercepts and slopes and adjusted for baseline age, participants' baseline age squared, sex, ethnicity, and childhood socioeconomic factors, we observed that most individual and cumulative ACE exposures had null to weakly negative associations with memory function and rate of decline over the 10-year follow-up. Having lived in residential or foster care was associated with lower baseline memory (adjusted ß = -0.124 standard deviation units; 95% confidence interval: -0.273, -0.025) but not memory decline. Our findings suggest potential long-term impacts of residential or foster care on memory and highlight the need for accurate and detailed exposure measures when studying ACEs in relation to later-life cognitive outcomes.


Asunto(s)
Adultos Sobrevivientes de Eventos Adversos Infantiles/psicología , Experiencias Adversas de la Infancia/estadística & datos numéricos , Envejecimiento Cognitivo/psicología , Trastornos de la Memoria/epidemiología , Adolescente , Anciano , Niño , Inglaterra/epidemiología , Femenino , Estudios de Seguimiento , Cuidados en el Hogar de Adopción/psicología , Cuidados en el Hogar de Adopción/estadística & datos numéricos , Humanos , Modelos Lineales , Estudios Longitudinales , Masculino , Trastornos de la Memoria/psicología , Persona de Mediana Edad , Instituciones Residenciales/estadística & datos numéricos , Factores Socioeconómicos
17.
BMJ Open ; 11(2): e044965, 2021 02 10.
Artículo en Inglés | MEDLINE | ID: mdl-33568377

RESUMEN

PURPOSE: The COVID-19 pandemic, beginning in early 2020, has resulted in massive social, economic, political and public health upheaval around the world. We established a national longitudinal cohort study, the COVID-19 Coping Study, to investigate the effects of pandemic-related stressors and changes in life circumstances on mental health and well-being among middle-aged and older adults in the USA. PARTICIPANTS: From 2 April to 31 May 2020, 6938 adults aged ≥55 years were recruited from all 50 US states, the District of Columbia and Puerto Rico using online, multi-frame non-probability-based sampling. FINDINGS TO DATE: Mean age of the baseline sample was 67.3 years (SD: 7.9 years) and 64% were women. Two in three adults reported leaving home only for essential purposes in the past week (population-weighted proportion: 69%; 95% CI: 68% to 71%). Nearly one in five workers aged 55-64 years was placed on a leave of absence or furloughed since the start of the pandemic (17%; 95% CI: 14% to 20%), compared with one in three workers aged ≥75 years (31%; 95% CI: 21% to 44%). Nearly one-third of adults screened positive for each of depression (32%; 95% CI: 30% to 34%), anxiety (29%; 28% to 31%) and loneliness (29%; 95% CI: 27% to 31%), with decreasing prevalence of each with increasing age. FUTURE PLANS: Monthly and annual follow-ups of the COVID-19 Coping Study cohort will assess longitudinal changes to mental health, cognitive health and well-being in relation to social, behavioural, economic and other COVID-19-related changes to life circumstances. Quantitative and in-depth qualitative interview data will be collected through online questionnaires and telephone interviews. Cohort data will be archived for public use.


Asunto(s)
Adaptación Psicológica , COVID-19/psicología , Salud Mental , Pandemias , Anciano , Anciano de 80 o más Años , Estudios de Cohortes , District of Columbia , Femenino , Humanos , Estudios Longitudinales , Masculino , Persona de Mediana Edad , Puerto Rico , Estados Unidos/epidemiología
18.
Phys Rev Lett ; 126(6): 064801, 2021 Feb 12.
Artículo en Inglés | MEDLINE | ID: mdl-33635713

RESUMEN

Sources of high-energy photons have important applications in almost all areas of research. However, the photon flux and intensity of existing sources is strongly limited for photon energies above a few hundred keV. Here we show that a high-current ultrarelativistic electron beam interacting with multiple submicrometer-thick conducting foils can undergo strong self-focusing accompanied by efficient emission of gamma-ray synchrotron photons. Physically, self-focusing and high-energy photon emission originate from the beam interaction with the near-field transition radiation accompanying the beam-foil collision. This near field radiation is of amplitude comparable with the beam self-field, and can be strong enough that a single emitted photon can carry away a significant fraction of the emitting electron energy. After beam collision with multiple foils, femtosecond collimated electron and photon beams with number density exceeding that of a solid are obtained. The relative simplicity, unique properties, and high efficiency of this gamma-ray source open up new opportunities for both applied and fundamental research including laserless investigations of strong-field QED processes with a single electron beam.

19.
Phys Rev Lett ; 124(10): 104801, 2020 Mar 13.
Artículo en Inglés | MEDLINE | ID: mdl-32216389

RESUMEN

Wakefield based accelerators capable of accelerating gradients 2 orders of magnitude higher than present accelerators offer a path to compact high energy physics instruments and light sources. However, for high gradient accelerators, beam instabilities driven by commensurately high transverse wakefields limit beam quality. Previously, it has been theoretically shown that transverse wakefields can be reduced by elliptically shaping the transverse sizes of beams in dielectric structures with planar symmetry. Here, we report experimental measurements that demonstrate reduced transverse wakefields for elliptical beams in planar symmetric structures which are consistent with theoretical models. These results may enable the design of gigavolt-per-meter gradient wakefield based accelerators that produce and stably accelerate high quality beams.

20.
Case Rep Womens Health ; 21: e00098, 2019 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-30733925

RESUMEN

Preeclampsia is a disease of pregnancy classically defined by the development of new-onset hypertension and proteinuria. Serous retinal detachment is a rare complication of severe preeclampsia that is associated with a high incidence of morbidity and mortality. We present the case of a 24-year-old primigravida who was diagnosed with preeclamptic serous retinal detachment at 30 weeks of gestation that occurred in the absence of hypertension. The patient was delivered by cesarean section for fetal malpresentation and she had complete recovery of her vision by three months postpartum. Providers should exercise vigilance for preeclampsia in women presenting with new-onset visual symptoms, even in the absence of hypertension.

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