Solar rejection in laser based underwater communication systems

This article provides a numerical study of the expected improvements in an underwater optical system given by a single-mode laser diode operating within a Fraunhofer line in a coastal water type. The system performance is examined for a silicon PIN direct-detection receiver in the euphotic zone. The solar irradiance, modelled as white noise, is evaluated when using a lithium niobate interference and a birefringent filter with different field-of-view (FOV) characteristics in a clear sky situation. The results of this analysis show the inverse dependence of the signal-to-noise (SNR) on the FOV, along with the significant improvement in the receiver sensitivity given by a narrow optical bandpass filter (OBPF)

The Management of Non-IgE-Mediated Allergies in Human Milk-Fed Infants

Background: Non-IgE (immunoglobulin E)-mediated food allergies (FA) present diagnostic and management challenges despite guidelines due to knowledge gaps amongst clinicians. Given that 60% of food protein-induced allergic proctocolitis (FPIAP) cases occur in breast-fed infants, maternal elimination diets are routinely prescribed to manage allergy symptoms. The implications of maternal dietary eliminations extend beyond maternal nutrition to consideration of infant nutrition and feeding skill acquisition. Methods: A survey-based retrospective, cross-sectional study sought to identify dietary triggers and symptom management techniques practiced by (n=59) lactating mothers of infants with confirmed and suspected cases of non-IgE FA in the United States. Statistical significance was set at p \u3c0.05 and correlations were performed using SPSS statistical software version 29.0. Results: Cow’s milk followed by soy represented the most common dietary antigens at 96.6% and 22.0% respectively of those surveyed. Of these, 88% reported maternal elimination of cow’s milk and 35.6% reported elimination of milk and soy. Only 14.3% of respondents received a referral to a dietitian. Among infants with confirmed or suspected non-IgE FA (n=59), 72.9% (n=43) continued breastfeeding during maternal elimination, 13.5% (n=8) transitioned to a hypoallergenic formula, and the other 5.1% (n=3) were fed a combination of breast milk and formula. The predominant symptoms reported were abdominal pain (59.3%), feeding difficulties (59.3%), and colic (50.8%). Conclusion: Based on the number of lactating mothers practicing cow’s milk avoidance, there are nutritional concerns for mothers and infants experiencing non-IgE FA. Dietitians can play a crucial role in supporting the breastfeeding mother through dietary eliminations for the management of non-IgE FA in their infant

Laser Based Underwater Communication Systems

We report on recent progress in the field of visible light communications including direct modulation of blue laser devices at data rates beyond 10 Gbit/s, and the transmission of 2.5 Gbit/s OOK data through water. We also discuss the advantages of operating with single mode laser devices and matched filtering at the receiver in the context of applications with significant solar background. The system performance for two types of direct-detection receivers, a PIN detector and less conventional silicon Photomultiplier technology will be presented

Psychometric properties of the Patient Assessment Of Chronic Illness Care measure: acceptability, reliability and validity in United Kingdom patients with long-term conditions.

BACKGROUND: The Patient Assessment of Chronic Illness Care (PACIC) is a US measure of chronic illness quality of care, based on the influential Chronic Care Model (CCM). It measures a number of aspects of care, including patient activation; delivery system design and decision support; goal setting and tailoring; problem-solving and contextual counselling; follow-up and coordination. Although there is developing evidence of the utility of the scale, there is little evidence about its performance in the United Kingdom (UK). We present preliminary data on the psychometric performance of the PACIC in a large sample of UK patients with long-term conditions. METHOD: We collected PACIC, demographic, clinical and quality of care data from patients with long-term conditions across 38 general practices, as part of a wider longitudinal study. We assess rates of missing data, present descriptive and distributional data, assess internal consistency, and test validity through confirmatory factor analysis, and through associations between PACIC scores, patient characteristics and related measures. RESULTS: There was evidence that rates of missing data were high on PACIC (9.6% - 15.9%), and higher than on other scales used in the same survey. Most PACIC sub-scales showed reasonable levels of internal consistency (alpha = 0.68 - 0.94), responses did not demonstrate high skewness levels, and floor effects were more frequent (up to 30.4% on the follow up and co-ordination subscale) than ceiling effects (generally <5%). PACIC demonstrated preliminary evidence of validity in terms of measures of long-term condition care. Confirmatory factor analysis suggested that the five factor PACIC structure proposed by the scale developers did not fit the data: reporting separate factor scores may not always be appropriate. CONCLUSION: The importance of improving care for long-term conditions means that the development and validation of measures is a priority. The PACIC scale has demonstrated potential utility in this regard, but further assessment is required to assess low levels of completion of the scale, and to explore the performance of the scale in predicting outcomes and assessing the effects of interventions.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are

A Class of Eccentric Binaries with Dynamic Tidal Distortions Discovered with Kepler

We have discovered a class of eccentric binary systems within the Kepler data archive that have dynamic tidal distortions and tidally-induced pulsations. Each has a uniquely shaped light curve that is characterized by periodic brightening or variability at time scales of 4-20 days, frequently accompanied by shorter period oscillations. We can explain the dominant features of the entire class with orbitally-varying tidal forces that occur in close, eccentric binary systems. The large variety of light curve shapes arises from viewing systems at different angles. This hypothesis is supported by spectroscopic radial velocity measurements for five systems, each showing evidence of being in an eccentric binary system. Prior to the discovery of these 17 new systems, only four stars, where KOI-54 is the best example, were known to have evidence of these dynamic tides and tidally-induced oscillations. We perform preliminary fits to the light curves and radial velocity data, present the overall properties of this class and discuss the work required to accurately model these systems.Comment: 13 pages, submitted to Ap

High Speed Visible Light Communication Using Blue GaN Laser Diodes

GaN-based laser diodes have been developed over the last 20 years making them desirable for many security and defence applications, in particular, free space laser communications. Unlike their LED counterparts, laser diodes are not limited by their carrier lifetime which makes them attractive for high speed communication, whether in free space, through fiber or underwater. Gigabit data transmission can be achieved in free space by modulating the visible light from the laser with a pseudo-random bit sequence (PRBS), with recent results approaching 5 Gbit/s error free data transmission. By exploiting the low-loss in the blue part of the spectrum through water, data transmission experiments have also been conducted to show rates of 2.5 Gbit/s underwater. Different water types have been tested to monitor the effect of scattering and to see how this affects the overall transmission rate and distance. This is of great interest for communication with unmanned underwater vehicles (UUV) as the current method using acoustics is much slower and vulnerable to interception. These types of laser diodes can typically reach 50-100 mW of power which increases the length at which the data can be transmitted. This distance could be further improved by making use of high power laser arrays. Highly uniform GaN substrates with low defectivity allow individually addressable laser bars to be fabricated. This could ultimately increase optical power levels to 4 W for a 20-emitter array. Overall, the development of GaN laser diodes will play an important part in free space optical communications and will be vital in the advancement of security and defence applications

The Partisan Consequences of Turnout Revisited

Why does the leftist party vote increase when turnout increases in some countries and not in others? Why does this happen in some instances in time but not in others? Thus far there exists no academic consensus on the relationship between turnout and electoral results. This paper argues that in order to adequately address these questions we need to focus on three elements: class voting, the mechanisms behind whether the correlation is observed over the short or long-term, and the use of more rigorous model specifications. By looking at the cases of Spain and Portugal, we find a correlation in the short and long-term for Spain but not for Portugal and this is due namely to the prominence of class voting in the former