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1.
Psychiatry Res ; 339: 116055, 2024 Jun 23.
Artículo en Inglés | MEDLINE | ID: mdl-38924900

RESUMEN

INTRODUCTION: Older adults are increasingly using medical cannabis (MC). It is unclear if therapeutic effects increase problematic use patterns. The current study addresses this issue by examining symptom trajectories across the day and using trajectories to predict problematic use. METHODS: One-hundred six older adults (age range 55-74) who endorsed medical conditions approved for treatment using MC were recruited online. Participants received six text messages/day to assess momentary symptoms for 15 days. RESULTS: Participants provided 5,156 momentary assessments across 1,106 use days. Symptom trajectories were examined across the day. There was a decline in all symptoms following use. Negative affect, pain, and nausea evinced momentary negative reinforcement associations with cannabis intoxication. Momentary negative reinforcement was associated with adverse cannabis outcomes. Declines in post-use trauma symptoms and momentary negative reinforcement effects for negative affect were both associated with cannabis use disorder symptoms. DISCUSSION: These data suggest that MC may be effective in reducing common symptom clusters. However, the negative reinforcing effect (i.e., the link between use and symptom relief at the event level) may complicate the therapeutic nature (i.e., symptom reduction). Identifying interventions to maximize benefits while minimizing costs may increase the efficacy and safety of MC in older adults.

2.
Clin Gerontol ; : 1-15, 2023 Aug 02.
Artículo en Inglés | MEDLINE | ID: mdl-37530457

RESUMEN

OBJECTIVES: Evidence-based interventions for dementia caregivers, such as the Savvy Caregiver Program (SC), seek to address skills and knowledge deficits, caregiver burden, depressive symptoms, and grief. Little research has examined mechanisms by which these interventions accomplish their goals. Caregiver preparedness may be a possible mechanism by which caregiver interventions may confer benefits. METHODS: The sample included 76 dementia caregivers who completed the 6-session SC. Participants completed the Anticipatory Grief Scale, Center for Epidemiological Studies-Depression Scale, the Preparedness for Caregiving Scale, and the Zarit Burden Interview-Short Form. RESULTS: A repeated measures ANOVA was utilized to determine the interaction between baseline scores and pre-post change in caregiver preparedness. Analysis significantly predicted caregiver burden, (F(1) = 6.68, p=.012, partial η2=.10), depressive symptom endorsement, (F(1) = 6.41, p=.014, partial η2=.09, and anticipatory grief, (F(1) = 6.22, p=.02, partial η2=.1), post-treatment. CONCLUSIONS: Pre-post change in caregiver preparedness significantly predicted pre-post change across measures of caregiver burden, depressive symptom endorsement, and anticipatory grief. Findings suggest that caregiver preparedness may be one mechanism by which the SC confers positive outcomes. These findings provide an empirical and theoretical basis for tailoring future dementia caregiver interventions. CLINICAL IMPLICATIONS: Clinical Interventions may seek to improve caregiver preparedness and subsequent outcomes through utilization of programs like SC.

3.
Cannabis ; 6(2): 22-29, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37484047

RESUMEN

Cannabis is increasingly accessible and use is increasing rapidly among older adults as laws change and cannabis becomes more frequently prescribed in healthcare settings. Past research identified cognitive effects of cannabis use among adolescents and young adults that can persist for several weeks after intoxication, though little is known about how these effects generalize to older adults. Participants (N = 1348) were drawn from the Health and Retirement Study (HRS) and were categorized as current occasional users (up to once/week in the past year, n = 36), current frequent users (once per week or more in the past year, n = 92), past users (n = 334), and non-users (n = 886). Participant ages ranged from 50 to 98 (M = 67.25, SD = 10.68). Uncontrolled, one-way ANOVAs and controlled ANCOVAs were used to examine between-group differences on immediate and delayed wordlist memory and working memory (serial sevens). When controlling for age, gender, education, and minority status, current frequent users demonstrated significantly worse immediate memory performance compared to past and non-users. However, this difference could have been the result of acute, residual effects of past-month cannabis use among current users. In controlled analyses, there were no differences between groups on delayed or working memory. Findings indicate that greater than weekly cannabis use may result in attentional and short-term memory deficits. Further, these effects may be mitigated by sustained abstinence. Limitations including sample size and measures of cannabis use warrant future studies to replicate and build upon these findings.

4.
Psychol Rep ; : 332941231161999, 2023 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-36921084

RESUMEN

The prevalence of eating pathology among college students has increased significantly in recent years. This coincides with increases in the use of cannabis, both nationally, but also among college students. Problematic cannabis use has been linked to eating pathology in prior research. Research also shows that cannabis may affect appetitive drives linked to food consumption. The current study tested the hypothesis that the association between problem cannabis use and eating pathology was mediated by greater loss of control eating. Cross-sectional data were collected from a sample of 805 college student cannabis users at a large Southeastern university in the U.S. The sample were primarily Caucasian (76%) and female (65.22%) with an average age of 20.15 (SD = 3.91). Participants completed surveys assessing eating outcomes (loss of control eating and eating pathology), cannabis use, and cannabis-related problems. The analysis used an observed variable path model. After controlling for cannabis use, cannabis-related problems were indirectly linked to eating pathology via loss of control eating (B = 0.109, SE = 0.025, p < .001), supporting the primary hypothesis. The direct relationship between cannabis-related problems and eating pathology was fully accounted for (B = 0.010, SE = 0.028, p = .724) by the indirect effect of loss of control eating. These data suggest that the association between problematic forms of cannabis use and eating pathology may be due to the association between cannabis problems and loss of control eating. While this may be due to changes in appetite and food evaluation as a function of more problematic use patterns, it may also be that individuals with problematic cannabis use have more problematic eating patterns due to deficits in adaptive coping strategies. Future research should seek to parse out these different potential explanations.

5.
Biol Open ; 11(12)2022 12 15.
Artículo en Inglés | MEDLINE | ID: mdl-36318109

RESUMEN

Plasticity in hatching time allows embryos to maximize fitness by balancing the benefits and costs of remaining bound within the chorion against the benefits and costs of emerging as a free-swimming larva. Here, in the first experiment, we exposed zebrafish (Danio rerio) embryos to either chemical cues from crushed embryos (simulating egg predation) or to blank water control. Embryos exposed to alarm cues hatched sooner, and had shorter body lengths and underdeveloped fins, relative to larvae from the water treatment. Burst swimming speed was significantly slower for larvae that hatched from the alarm cue treatment than for larvae from the water treatment. In a second 2×2 experiment, we exposed zebrafish embryos to either chemical alarm cues from conspecific embryos, mechanical disturbance (magnetic stir bar) to simulate a predator probing the substrate for developing embryos, both chemical and mechanical indicators of risk, or neither (control). We found similar effects in terms of earlier time to hatch at an earlier stage of development and poorer swimming performance of hatchling larvae. In the second experiment, these effects occurred in response to mechanical disturbance with or without the presence of chemical alarm cues. Alarm cues alone produced no effects in the second experiment. Taken together, these data indicate that zebrafish embryos demonstrate a facultative trade-off between risk of predation acting on two stages of their life history.


Asunto(s)
Conducta Predatoria , Pez Cebra , Animales , Pez Cebra/metabolismo , Larva , Natación , Señales (Psicología)
6.
Clin Gerontol ; 45(4): 998-1009, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-32684094

RESUMEN

OBJECTIVES: The purpose of this pilot study is to examine the efficacy of a theoretically based, 6-week dementia caregiver support group in a primary care setting. METHODS: Using a quasi-experimental design, 22 participants completed the caregiver support group. Participants were mostly in their mid-60 s (M = 63 years old), female (n = 19), Caucasian (n = 14), and identified as either the care recipient's child or spouse (n = 19). At baseline and 6 weeks, participants completed self-report measures related to demographic information, caregiver preparedness, strain, and depressive symptoms, and care recipient's neuropsychiatric symptoms. Participants also completed a satisfaction survey. Within-subjects t-tests were run to determine if participants' scores changed over time. RESULTS: Results revealed that participants demonstrated a significant increase in mean caregiver preparedness scores. No significant effects were found for caregiver strain, depressive symptoms, and distress related to neuropsychiatric symptoms. Participants rated being largely satisfied with the program. CONCLUSIONS: Results suggest that this 6-week caregiver support group may be a promising caregiver intervention in primary care clinics. CLINICAL IMPLICATIONS: Findings support the importance of caregiver support for persons with dementia in primary care.


Asunto(s)
Cuidadores , Demencia , Grupos de Autoayuda , Cuidadores/psicología , Demencia/terapia , Familia , Femenino , Humanos , Persona de Mediana Edad , Proyectos Piloto , Atención Primaria de Salud
7.
Aging Ment Health ; 26(11): 2179-2185, 2022 11.
Artículo en Inglés | MEDLINE | ID: mdl-34596476

RESUMEN

OBJECTIVES: Previous research has found that many incarcerated individuals have mental health conditions and that incarcerated women may be at elevated risk. These individuals have been shown to experience mental health concerns shortly after their release, but little is known about their mental health later in life. This study compared depressive symptoms in older adults with and without a history of incarceration and examined the impact of gender on this relationship. METHOD: Data from 160 pairs of adults aged 65 or older (82.5% male, mean age = 73.4 years) who participated in the 2012 wave of the Health and Retirement Study (HRS) was utilized. Older adults with a history of incarceration were matched to those without based on age, gender, race, and education level. Depressive symptoms (CES-D) of older adults with and without a history of incarceration were compared using a repeated-measures ANOVA. RESULTS: The main effect of incarceration history (p=.001, partial eta2=.07) and the interaction between incarceration history and gender (p=.01, partial eta2=.04) were significant. Follow-up analyses revealed that the difference between depressive symptoms for older women with and without a history of incarceration was significant (p=.02, d = 0.69), whereas the difference for older men was not significant (p=.19, d = 0.16). CONCLUSIONS: Findings suggest older adults with a history of incarceration report more depressive symptoms than those without and that the effect is seen among older women. Negative effects of incarceration on mental health may therefore persist into later life, highlighting the importance of pre- and post-release mental health services.


Asunto(s)
Depresión , Trastornos Mentales , Humanos , Masculino , Femenino , Anciano , Depresión/psicología , Jubilación , Salud Mental , Escolaridad
8.
Aging Ment Health ; 25(11): 2061-2067, 2021 11.
Artículo en Inglés | MEDLINE | ID: mdl-32614616

RESUMEN

OBJECTIVES: Findings on the health impact of moderate alcohol use in later-life have been discrepant. Unaddressed mechanisms of action and validity concerns may contribute to contrasting results. Several studies have demonstrated a beneficial relationship between moderate alcohol use and functional ability. Research is needed to identify mechanisms of action that explain this relationship, while employing methods to reduce common validity concerns in alcohol use research. This study examines social interaction and depressive symptoms as serial mediators in the relationship between moderate alcohol use and functional limitation in later-life. METHOD: HRS data from 2012-2016 were utilized (n = 1,474); heavy drinkers, adults younger than 65, and respondents with inconsistent alcohol use from 2008 to 2016 were excluded. Hypotheses were evaluated using a longitudinal serial mediation model with bias-corrected bootstrapping. RESULTS: Results indicated that, in the context of demographic variables, medical burden, and previous functional limitation, the relationship between 2012 moderate alcohol use and 2016 reduced functional limitation is only present when considering the mediating effect of 2014 depressive symptoms as a single mediator, and 2012 social interaction and 2014 depressive symptoms as serial mediators, respectively (total effect model R2=.167). CONCLUSIONS: Data indicate that relationships between moderate drinking and reduced functional limitation are explained through increased social interaction and subsequent reduced depressive symptoms. Results identify social interaction as an accessible treatment target to address depressive symptoms and functional limitation, and support increased assessment of IADLs in adults experiencing depressive symptoms (and vice versa) to facilitate early treatment/prevention of functional and emotional decline.


Asunto(s)
Tristeza , Socialización , Actividades Cotidianas , Consumo de Bebidas Alcohólicas/epidemiología , Depresión/epidemiología , Humanos
9.
Appl Opt ; 59(30): 9434-9442, 2020 Oct 20.
Artículo en Inglés | MEDLINE | ID: mdl-33104661

RESUMEN

Imaging and target recognition through strong turbulence is regarded as one of the most challenging problems in modern turbulence research. As the aggregated turbulence distortion inevitably degrades remote targets and makes them less recognizable, both adaptive optics approaches and image correction methods will become less effective in retrieving correct attributes of the target. Meanwhile, machine learning (ML)-based algorithms have been proposed and studied using both hardware and software approaches to alleviate turbulence effects. In this work, we propose a straightforward approach that treats images with turbulence distortion as a data augmentation in the training set, and investigate the effectiveness of the ML-assisted recognition outcomes under different turbulence strengths. Retrospectively, we also apply the recognition outcomes to evaluate the turbulence strength through regression techniques. As a result, our study helps to build a deep connection between turbulence distortion and imaging effects through a standard perceptron neural network (NN), where mutual inference between turbulence levels and target recognition rates can be achieved.

10.
Innov Aging ; 4(4): igaa039, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-33123629

RESUMEN

BACKGROUND AND OBJECTIVES: Age-associated financial vulnerability was introduced because it was increasingly recognized that cognitively intact older adults experienced changes that rendered them financially vulnerable. In this study, we attempt to apply the construct of Age-Associated Financial Vulnerability to a measure of Perceived Financial Vulnerability and whether this perceived vulnerability is predicted by risk factors from the 4 categorical domains used to define Age-Associated Financial Vulnerability's impact. RESEARCH DESIGN AND METHODS: This study was part of the Health and Retirement Study (HRS) survey in 2018. The survey contained 7 experimental module items of Perceived Financial Vulnerability. One thousand three hundred fourteen participants completed the Perceived Financial Vulnerability measure. The sample was drawn from Waves 13 and 14 of the HRS (2016 and 2018, respectively). The measurement of Perceived Financial Vulnerability was developed on the basis of 7 questions assessing financial awareness and psychological vulnerability items regarding personal finance that were included in the 2018 HRS data collection. Predictors included measures of cognition, function/health, depression, and wealth. Predictor measures from 2016 were regressed on 2018 Perceived Financial Vulnerability scores. RESULTS: Six items of Perceived Financial Vulnerability had psychometric properties acceptable for a new measure. Responses revealed variability in Perceived Financial Vulnerability. Overall, 18% of variance was accounted for and measures from cognition, depression, assets, and functional abilities were all unique and significant predictors. DISCUSSION AND IMPLICATIONS: This study represents both a conceptual and empirical contribution to our understanding of older adult's perceptions of financial vulnerability. The high levels of Perceived Financial Vulnerability found in this normative sample underscore the importance of context in understanding people's economic behaviors. For instance, more than one half of the sample indicated that they wished they had someone to talk to about their finances. This desire to talk with others is normative and yet often underappreciated.

11.
Opt Lett ; 45(16): 4428-4431, 2020 Aug 15.
Artículo en Inglés | MEDLINE | ID: mdl-32796975

RESUMEN

We present a new, to the best of our knowledge, concept of using quadrant Fourier transforms (QFTs) formed by microlens arrays (MLAs) to decode complex optical signals based on the optical intensity collected per quadrant area after the MLAs. From a computational optics viewpoint, we show the most promising use of the QFT in low-cost and passive decoding of laser signals carrying optical angular momenta (OAM) that are prevalent in research frontiers of optical communications, computation, and imaging. There are numerous ways of creating, adding, and combining OAM states in optical waves, while decoding or demultiplexing approaches often turn out to be complicated or expensive. The simple OAM decoder formed by a pair of identical MLAs, which are concatenated in the focal plane and transversely offset by half-pitch length, can accomplish the imaging task with four pixels per cell. By sorting the gradient curls of the optical wave into local quadrant cells, the decoder analyzes the intensity reallocation that is proportional to the gradients and computes the gradient curls accordingly. The low-cost, compactness, and simplicity of the proposed OAM sensor will further promote OAM-based applications, as well as many other applications that exploit the spatial complexity of optical signals.

12.
Opt Lett ; 45(5): 1156-1159, 2020 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-32108794

RESUMEN

Understanding turbulence effects on laser beam propagation is critical to the emerging design, study, and test of many long-range free space optical (FSO) communication and directed energy systems. Conventional studies make the prevalent assumption of isotropic turbulence, while more recent results suggest anisotropic turbulence for atmospheric channels within a few meters elevation above the ground. As countless FSO systems have been and continue to be deployed in such channels, analysis of anisotropic modelings has become one of the fastest growing areas in FSO research. This in turn motivates new tools that can distinguish anisotropic characteristics to improve both modeling accuracy and physical interpretations. Wavefront sensors such as Shack-Hartmann sensors, interferometers, and plenoptic sensors have been devised and used in experiments; however, they all require rigid alignments that lack resilience against temperature gradient buildup and beam wander. We find that by using a light field camera (LFC) that extracts perturbation of individual light rays, the wave structure function of turbulence can be retrieved with high reliability. Furthermore, we find through experiments that the outer scales of near-ground turbulence tend to be a magnitude smaller than conventional theoretical assumptions, agreeing with new findings by others but being absent in current theoretical modelings. As a result, we believe that the LFC is an ideal candidate in the frontier of turbulence research; it is both commercially available and easy to adapt to turbulence experiments.

13.
Gerontologist ; 60(1): 80-88, 2020 01 24.
Artículo en Inglés | MEDLINE | ID: mdl-30358833

RESUMEN

BACKGROUND AND OBJECTIVES: Evidence relates moderate alcohol consumption in later life to fewer depressive symptoms and greater functional ability. This study evaluated social interaction as a mediator of these outcomes. RESEARCH DESIGN AND METHODS: Data included older adults in the Health and Retirement Study. In Study 1, cross-sectional mediation analyses evaluated social interaction as a mechanism through which moderate alcohol use was related to decreased depressive symptomatology (Model 1; N = 2,294) and less functional limitation (Model 2; N = 2,357). In Study 2, longitudinal cross-lagged path analyses further evaluated the impact of moderate alcohol use and social interaction on future depressive symptoms and functional limitation. RESULTS: In Study 1, results from Model 1 indicated that moderate alcohol use was associated with decreased depressive symptomatology indirectly via greater social interaction. In Model 2, moderate alcohol use was associated with less functional limitation indirectly via greater social interaction. In Study 2, significant indirect effects corroborated findings from Study 1. In Model 3, moderate alcohol use in 2012 inversely predicted depressive symptomatology in 2014 via greater levels of social interaction in 2012. In Model 4, moderate alcohol use in 2012 predicted less functional limitation in 2014 via greater social interaction in 2012. DISCUSSION AND IMPLICATIONS: Social interaction is essential to the seemingly beneficial effect of moderate alcohol use on depressive symptomatology and functional ability. Clinically, this suggests caution in attributing health benefits to consumption of alcohol itself and identifies social interaction as a treatment target for improved health outcomes in later life.


Asunto(s)
Actividades Cotidianas/psicología , Consumo de Bebidas Alcohólicas/epidemiología , Depresión/epidemiología , Relaciones Interpersonales , Afecto , Anciano , Anciano de 80 o más Años , Estudios Transversales , Femenino , Conductas Relacionadas con la Salud , Humanos , Estudios Longitudinales , Masculino , Jubilación
14.
Appl Opt ; 58(25): 6934-6941, 2019 Sep 01.
Artículo en Inglés | MEDLINE | ID: mdl-31503665

RESUMEN

Optical turbulence can have a severe effect on the propagation of laser beams through the atmosphere. In free space optics and directed energy applications, these laser beams quite often propagate along a slant or vertical path. In these cases, the refractive index structure function parameter cannot be assumed constant, since it varies with height. How it varies with height, especially in the first few meters above the ground, is not well behaved. Turbulence height profiles have been measured since the 1970s, mainly for astronomical observations. These profiles are usually measured for the atmospheric boundary layer (the layer of air from the ground up to approx. 1 km during day and 100 m during night) and some kilometers above it. We have measured the temperature fluctuations in the first few meters above ground level using a system containing eight resistance thermometer devices, mounted in a row at different spacings. Measurements were made flying this system under a tethered balloon or mounted on a telescoping mast. The temperature structure function parameter, CT2, can be estimated from the temperature fluctuations measured by the 28 different probe pairs and the unique distances between the two probes. Finally, Cn2 is estimated from this temperature structure function parameter and compared to values predicted by a turbulence profile model.

15.
J Gerontol Soc Work ; 62(4): 392-398, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-30724686

RESUMEN

The attempted Quality of Life Enhancement program appeared to be a novel method for creating a symbiotic and sustainable relationship between a large Southeastern university and local nursing home and assisted living facilities (ALF), through which ALF residents would attend university arts and sporting events. During implementation, it was discovered that this project was unsustainable, undesired, unneeded by many care centers, difficult to implement, and required a dedicated and specialized staff. After attempting to enroll 14 local care facilities, only 2 were interested in becoming involved and produced 5 eligible participants. During the program itself, coordination with facilities and residents was difficult to maintain and unique transportation and accommodation needs were challenging to overcome. Finally, data collection was time consuming and generally unfruitful. Ultimately the project was discontinued after a year of attempted recruitment and implementation of inclusive changes to protocol. While creating an ongoing relationship with local care facilities and local universities may enhance opportunities for residents and research into important areas, such relationships take time, effort, and specialized staff to maintain.


Asunto(s)
Relaciones Comunidad-Institución/normas , Evaluación de Programas y Proyectos de Salud , Calidad de Vida , Instituciones de Vida Asistida , Humanos , Casas de Salud , Proyectos de Investigación/normas
16.
J Health Psychol ; 24(9): 1201-1209, 2019 08.
Artículo en Inglés | MEDLINE | ID: mdl-28810403

RESUMEN

Survivors of differentiated thyroid cancer report significant distress. This study examines illness perceptions as mediating the relationship between information support and distress among survivors of differentiated thyroid cancer. Data were obtained from the Patient Reported Outcomes Following Initial Treatment and Long-term Evaluation of Survivorship registry. Model results revealed that greater information support was associated with better illness perceptions, and that better illness perceptions were associated with less distress. Information support and distress were indirectly related via illness perceptions. Results highlight the importance of addressing illness perceptions in this population and suggest that informational interventions may help serve this function.


Asunto(s)
Actitud Frente a la Salud , Comunicación en Salud/métodos , Estrés Psicológico/psicología , Sobrevivientes/psicología , Neoplasias de la Tiroides/psicología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Países Bajos , Medición de Resultados Informados por el Paciente , Sistema de Registros , Encuestas y Cuestionarios , Sobrevivientes/estadística & datos numéricos
17.
Am J Alzheimers Dis Other Demen ; 34(2): 118-123, 2019 03.
Artículo en Inglés | MEDLINE | ID: mdl-30384769

RESUMEN

For individuals with dementia, disorientation and both external and internal stimuli may trigger behaviors that are difficult to manage or dangerous to health-care providers. Identification of correlational risk factors to aggressive behavior in patients who are unknown to the hospital can allow providers to adapt patient care quickly. Records for patients aged 60+ who spent at least 24 hours at the hospital other than in the psychiatric unit were used (N = 14 080). The first 4000 records and every 10th person who met criteria (N = 5008) were searched for documentation of dementia (n = 505). Logistic regressions and χ2 tests were used to examine relationships between variables. Recognition of delirium (P = .014, Exp(B) = 2.53), coupled with an existing prescription for antipsychotic medication at intake (P < .001, Exp(B) < 4.37), may be a reliable means of screening for risk and intervening at the earliest possible contact, improving quality of care and safety in acute care for individuals with dementia.


Asunto(s)
Agresión/psicología , Antipsicóticos/uso terapéutico , Delirio/tratamiento farmacológico , Demencia/psicología , Tamizaje Masivo , Anciano , Femenino , Humanos , Pacientes Internos/psicología , Masculino , Factores de Riesgo
18.
Appl Opt ; 57(9): 2177-2187, 2018 Mar 20.
Artículo en Inglés | MEDLINE | ID: mdl-29604011

RESUMEN

Image distortions caused by atmospheric turbulence are often treated as unwanted noise or errors in many image processing studies. Our study, however, shows that in certain scenarios the turbulence distortion can be very helpful in enhancing image processing results. This paper describes a novel approach that uses the scintillation traits recorded on a video clip to perform object ranging with reasonable accuracy from a single camera viewpoint. Conventionally, a single camera would be confused by the perspective viewing problem, where a large object far away looks the same as a small object close by. When the atmospheric turbulence phenomenon is considered, the edge or texture pixels of an object tend to scintillate and vary more with increased distance. This turbulence induced signature can be quantitatively analyzed to achieve object ranging with reasonable accuracy. Despite the inevitable fact that turbulence will cause random blurring and deformation of imaging results, it also offers convenient solutions to some remote sensing and machine vision problems, which would otherwise be difficult.

19.
Appl Opt ; 57(9): 2337-2345, 2018 Mar 20.
Artículo en Inglés | MEDLINE | ID: mdl-29604033

RESUMEN

We find that ideas in optical image encryption can be very useful for adaptive optics in achieving simultaneous phase and amplitude shaping of a laser beam. An adaptive optics system with simultaneous phase and amplitude shaping ability is very desirable for atmospheric turbulence compensation. Atmospheric turbulence-induced beam distortions can jeopardize the effectiveness of optical power delivery for directed-energy systems and optical information delivery for free-space optical communication systems. In this paper, a prototype adaptive optics system is proposed based on a famous image encryption structure. The major change is to replace the two random phase plates at the input plane and Fourier plane of the encryption system, respectively, with two deformable mirrors that perform on-demand phase modulations. A Gaussian beam is used as an input to replace the conventional image input. We show through theory, simulation, and experiments that the slightly modified image encryption system can be used to achieve arbitrary phase and amplitude beam shaping within the limits of stroke range and influence function of the deformable mirrors. In application, the proposed technique can be used to perform mode conversion between optical beams, generate structured light signals for imaging and scanning, and compensate atmospheric turbulence-induced phase and amplitude beam distortions.

20.
Appl Opt ; 57(3): 551-559, 2018 Jan 20.
Artículo en Inglés | MEDLINE | ID: mdl-29400780

RESUMEN

We present the theory, design, simulation, and experimental evaluations of a new laser transmissometer system for aerosol extinction rate measurement over long paths. The transmitter emits an ON/OFF modulated Gaussian beam that does not require strict collimation. The receiver uses multiple point detectors to sample the sub-aperture irradiance of the arriving beam. The sparse detector arrangement makes our transmissometer system immune to turbulence-induced beam distortion and beam wander caused by the atmospheric channel. Turbulence effects often cause spatial discrepancies in beam propagation and lead to miscalculation of true power loss when using the conventional approach of measuring the total beam power directly with a large-aperture optical concentrator. Our transmissometer system, on the other hand, combines the readouts from distributed detectors to rule out turbulence-induced temporal power fluctuations. As a result, we show through both simulation and field experiments that our transmissometer system works accurately with turbulence strength Cn2 up to 10-12 m-2/3 over a typical 1-km atmospheric channel. In application, our turbulence- and weather-resistant laser transmissometer system has significant advantages for the measurement and study of aerosol concentration, absorption, and scattering properties, which are crucial for directed energy systems, ground-level free-space optical communication systems, environmental monitoring, and weather forecasting.

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