497 research outputs found

    The prevalence and incidence of glaucoma in Denmark in a fifteen year period:a nationwide study

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    The purpose of the present study was to describe the prevalence, incidence and geographic variation of glaucoma in Denmark in the period from 1996 to 2011. Moreover, the aim was to identify the treatment patterns of glaucoma within the studied period.All Danish citizens were included throughout the study period. The National Prescription Registry was used to identify all claimed prescriptions for glaucoma medication.A total of 116,592 incident glaucoma patients were identified. Average age at onset was 66 years (range: 0-105 years), 55% were women. The prevalence of glaucoma increased from 0.79% to 1.72% during the investigated period. In 2011 glaucoma affected 3.76% of the population above 50 years and 10% in patients above 80 years. The age-specific incidence rate of glaucoma seemed to be constant and the increasing prevalence was primarily attributed to an aging population. We found the highest prevalence of glaucoma in the capital region of Denmark. Within the studied period the use of prostaglandin analogs and combination drugs increased, whereas the use of β-blockers, carbon anhydrase inhibitors and parasympathomimetic drugs decreased (p<0.001). Finally, the use of α2-adrenergic agonists remained unchanged. A total of 75% of the patients were treated with two or more glaucoma medications.Over all, the present study is the first to assess the frequency and the development of glaucoma in Denmark over a 15-year period. We find that glaucoma affects a little less than 2% of the total population and increases with age to reach a prevalence of more than 10% amongst people above 80 years. Generally, the present study is the largest nation-wide study ever made and must be a close-to-real-life-picture of the utilization of glaucoma medication on a national scale. Our findings confirm other recent estimations on an increasing burden of glaucoma globally

    Terabit/s serial optical communications:[invited]

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    Reduced timing Sensitivity in all-optical switching using flat-top control pulses obtained by the optical fourier transform technique

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    For high-speed serial data, timing tolerance is crucial for switching and regeneration. We propose a novel scheme to generate flat-top pulses, for use as gating control pulses. The scheme relies on spectral shaping by a square-shaped filter, followed by a linear transformation of the spectral shape into the time domain, referred to as the optical Fourier transform technique. A 3 ps flat-top pulse derived from a 3 nm wide square filter is obtained, and used to gate an all-optical OTDM demultiplexer, yielding an error-free timing jitter tolerance of 3 ps for 80 Gb/s and 160 Gb/s data signals.</p

    An EIS alternative for impedance measurement of a high temperature PEM fuel cell stack based on current pulse injection

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    In this paper a method for estimating the fuel cell impedance is presented, namely the current pulse injection (CPI) method, which is well suited for online implementation. This method estimates the fuel cell impedance and unlike electrochemical impedance spectroscopy (EIS), it is simple to implement at a low cost. This makes it appealing as a characterization method for on-line diagnostic algorithms. In this work a parameter estimation method for estimation of equivalent electrical circuit (EEC) parameters, which is suited for on-line use is proposed. Tests on a 10 cell high temperature PEM fuel cell show that the method yields consistent results in estimating EEC parameters for different current pulse at different current loads, with a low variance. A comparison with EIS shows that despite its simplicity the response of CPI can reproduce well the impedance response of the high and intermediate frequencies
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