8,480 research outputs found
Spectral atmospheric observations at Nantucket Island, May 7-14, 1981
An experiment was conducted by the National Langley Research Center to measure atmospheric optical conditions using a 10-channel solar spectral photometer system. This experiment was part of a larger series of multidisciplinary experiments performed in the area of Nantucket Shoals aimed at studying the dynamics of phytoplankton production processes. Analysis of the collected atmospheric data yield total and aerosol optical depths, transmittances, normalized sky radiance distributions, and total and sky irradiances. Results of this analysis may aid in atmospheric corrections of remote sensor data obtained by several sensors overflying the Nantucket Shoals area. Recommendations are presented concerning future experiments using the described solar photometer system and calibration and operational deficiencies uncovered during the experiment
The combined association of depressive symptoms and C-reactive protein for incident disease risk up to 12 years later. Findings from the English Longitudinal of Ageing (ELSA)
BACKGROUND: Depression and inflammation are interrelated, and both are associated with the development of long-term conditions (LTCs). We investigated whether the combination of elevated depressive symptoms and elevated C-reactive protein (CRP) was associated with the rate of onset of a range of LTCs. METHODS: We analysed data from 5360 participants (65.77±9.46 years; 54.1% female) from the English Longitudinal Study of Ageing (ELSA). Depressive symptoms were indicated using the Centre for Epidemiological Studies Depression (CES-D) scale and scores were combined with high sensitivity (hs)-CRP values to reflect the additive interaction between low/high depressive symptoms (CES-D ≥4) and low/high CRP (>3mg/L). Participants were followed-up for up to 12 years to predict incident illness. Cox proportional hazard regression was used controlling for covariates. RESULTS: In fully adjusted models, the combination of elevated depressive symptoms and elevated CRP was an independent predictor of CHD (HR = 1.68, 95% C.I. = 1.01-2.78), stroke (HR = 2.02; 95% C.I. = 1.48-2.76), diabetes/high blood glucose (HR = 1.69; 95% C.I. = 1.11-2.57), and pulmonary disease (HR = 1.79; 95% C.I. = 1.02-3.15) relative to low depressive symptoms/low CRP, independently of age, sex, wealth, cohabitation, smoking status, body mass index and hypertension. Elevated depressive symptoms and low CRP was associated with arthritis incidence (HR = 1.49; 95% C.I. = 1.15-1.92). No association was found for cancer incidence. CONCLUSION: A combination of depressive symptoms and CRP was implicated in the onset of CHD, stroke, diabetes/high blood glucose, and pulmonary disease up to 12 years later, reflecting the role of psychobiological processes across multiple disease states
Reducing Polarization Mode Dispersion With Controlled Polarization Rotations
One of the fundamental limitations to high bit rate, long distance,
telecommunication in optical fibers is Polarization Mode Dispersion (PMD). Here
we introduce a conceptually new method to reduce PMD in optical fibers by
carrying out controlled rotations of polarization at predetermined locations
along the fiber. The distance between these controlled polarization rotations
must be less than both the beat length and the mode coupling length of the
fiber. This method can also be combined with the method in which the fiber is
spun while it drawn. The incidence of imperfections on the efficiency of the
method is analysed.Comment: 4 page
Neural network-based ionospheric modelling over the South African region
During the past decade, South African scientists have pioneered research in the field of ionospheric modelling using the technique of neural networks (NNs). Global ionospheric models have always been insufficient for the South African region owing to an historical paucity of available data. Within the past 10 years, however, three new ionospheric sounders have been installed locally and are operating continuously. These sounders are located at Grahamstown (33.3°S, 26.5°E), Louisvale (28.5°S, 21.2°E) and Madimbo (22.4°S, 30.9°E). The addition of a modern sounder at Grahamstown enlarged the ionospheric database for this station to 30 years, making this archive a considerable asset for ionospheric research. Quality control and online availability of the data has also added to its attraction. An important requirement for empirical modelling, but especially for employing NNs, is a large database describing the history of the relationship between the ionosphere and the geophysical parameters that define its behaviour. This review describes the path of South African ionospheric modelling over the past 10 years, the role of NNs in this development, the international collaborations that have arisen from this, and the future of ionospheric modelling in South Africa
Ince's limits for confluent and double-confluent Heun equations
We find pairs of solutions to a differential equation which is obtained as a
special limit of a generalized spheroidal wave equation (this is also known as
confluent Heun equation). One solution in each pair is given by a series of
hypergeometric functions and converges for any finite value of the independent
variable , while the other is given by a series of modified Bessel functions
and converges for , where denotes a regular singularity.
For short, the preceding limit is called Ince's limit after Ince who have used
the same procedure to get the Mathieu equations from the Whittaker-Hill ones.
We find as well that, when tends to zero, the Ince limit of the
generalized spheroidal wave equation turns out to be the Ince limit of a
double-confluent Heun equation, for which solutions are provided. Finally, we
show that the Schr\"odinger equation for inverse fourth and sixth-power
potentials reduces to peculiar cases of the double-confluent Heun equation and
its Ince's limit, respectively.Comment: Submitted to Journal of Mathmatical Physic
Learning our lesson: using past policies to improve digital and ethnic inequalities beyond the pandemic
COVID-19 has had a disproportionate impact on ethnic minorities in the UK, raising questions about whether learning from the past few decades about the interplay between ethnicity and health inequalities has been effectively incorporated in current health policy. As digital health approaches, such as remote consultations and apps, become more widespread during and after the pandemic, it is important to ensure that these do not contribute to 'widening the gap'. We highlight three areas in which existing knowledge and evidence can be translated into cross-sectoral action to avoid further ethnic and digital health inequalities: data and measurement, improved communication, and embedded equality impact
Summary of Results of Field Experiments.
The aim of these experiments was to determine the relationship between bromegrass and ryegrass densities and their effects on wheat yields and in one case lupin yield 81 BA 45, Competition between bromegrass, ryegrass and wheat. 81 KA 28, Competition between bromegrass, ryegrass and wheat. 81 ME 35, Competition between bromegrass, ryegrass and wheat 81 TS 28, Competition between bromegrass, ryegrass and wheat. 81 WH 48, Competition between bromegrass, ryegrass and wheat. 81 NA 30, Competition between bromegrass, ryegrass and wheat. 81 MT 42, Abandoned due to severe waterlogging and disease. The wheat failed. The weeds grew magnificently. 81 MO 33, Competition between bromegrass, ryegrass and lupin
Enjoyment of life predicts reduced type 2 diabetes incidence over 12 years of follow-up: findings from the English Longitudinal Study of Ageing
BACKGROUND: Subjective well-being appears to be associated with reduced risk of type 2 diabetes (T2D). However, it is unknown whether this association is similar across different types of well-being. We examined the relationship between hedonic and eudaimonic well-being and incident T2D, and explored the role of sociodemographic, behavioural and clinical factors in these associations. METHODS: We used data from 4134 diabetes-free participants from the English Longitudinal Study of Ageing (mean age =64.97). Enjoyment of life and purpose in life were assessed using items from the CASP-19 to reflect hedonic and eudaimonic well-being, respectively. Participants reported T2D diagnosis over 12 years. We used Cox proportional hazards regression analyses and also explored the percentage of association explained by different covariates. RESULTS: Results revealed a protective role for enjoyment of life in T2D rate adjusting for sociodemographic (age, sex, wealth, ethnicity, marital status), behavioural (physical activity, smoking, alcohol consumption, body mass index) and clinical (hypertension, coronary heart disease and glycated haemoglobin) characteristics (HR =0.93, p=0.021, 95% CI (0.87, 0.99)). Sociodemographic, behavioural and clinical factors accounted for 27%, 27% and 18% of the association, respectively. The relationship between purpose in life and T2D was non-significant (adjusted HR =0.92, p=0.288, 95% CI (0.78, 1.08)). CONCLUSION: This study illustrates how the link between subjective well-being and T2D varies between well-being components. It also demonstrates that sociodemographic, behavioural and clinical factors partially explain this association. Intervention studies examining whether changes in enjoyment of life can help delay T2D onset are warranted
Magnetization dynamics in the single-molecule magnet Fe8 under pulsed microwave irradiation
We present measurements on the single molecule magnet Fe8 in the presence of
pulsed microwave radiation at 118 GHz. The spin dynamics is studied via time
resolved magnetization experiments using a Hall probe magnetometer. We
investigate the relaxation behavior of magnetization after the microwave pulse.
The analysis of the experimental data is performed in terms of different
contributions to the magnetization after-pulse relaxation. We find that the
phonon bottleneck with a characteristic relaxation time of 10 to 100 ms
strongly affects the magnetization dynamics. In addition, the spatial effect of
spin diffusion is evidenced by using samples of different sizes and different
ways of the sample's irradiation with microwaves.Comment: 14 pages, 12 figure
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