Long-period gratings for monitoring the resin transfer molding of fiber-reinforced polymer composites.

The spectral characteristics of long-period gratings (LPGs) have been researched over the last two decades, and many sensing applications of LPGs have been proposed due to their spectral sensitivity to many surrounding environmental parameters such as the temperature, pressure, and refractive index. However, this sensitivity to many parameters can also be a curse due to cross-sensitivity and the inability to distinguish which environmental parameter is responsible for the LPG's spectral behavior. For the application proposed here-monitoring the progress of a resin flow front, its velocity, and the permeability of the reinforcement mats during the infusion stage of resin transfer molding-the multi-sensitivity of LPGs is a distinct advantage, as it provides the ability to monitor the mold environment at various stages of manufacturing.

Breaking the Entangling Gate Speed Limit for Trapped-Ion Qubits Using a Phase-Stable Standing Wave.

All laser-driven entangling operations for trapped-ion qubits have hitherto been performed without control of the optical phase of the light field, which precludes independent tuning of the carrier and motional coupling. By placing ^{88}Sr^{+} ions in a λ=674 nm standing wave, whose relative position is controlled to ≈λ/100, we suppress the carrier coupling by a factor of 18, while coherently enhancing the spin-motion coupling. We experimentally demonstrate that the off-resonant carrier coupling imposes a speed limit for conventional traveling-wave Mølmer-Sørensen gates; we use the standing wave to surpass this limit and achieve a gate duration of 15 µs, restricted by the available laser power.

Ultraviolet A radiation and COVID-19 deaths in the USA with replication studies in England and Italy.

BACKGROUND: Understanding factors impacting deaths from COVID-19 is of the highest priority. Seasonal variation in environmental meteorological conditions affects the incidence of many infectious diseases and may also affect COVID-19. Ultraviolet (UV) A (UVA) radiation induces release of cutaneous photolabile nitric oxide (NO) impacting the cardiovascular system and metabolic syndrome, both COVID-19 risk factors. NO also inhibits the replication of SARS-CoV2. OBJECTIVES: To investigate the relationship between ambient UVA radiation and COVID-19 deaths. METHODS: COVID-19 deaths at the county level, across the USA, were modelled in a zero-inflated negative-binomial model with a random effect for states adjusting for confounding by demographic, socioeconomic and long-term environmental variables. Only those areas where UVB was too low to induce significant cutaneous vitamin D3 synthesis were modelled. We used satellite-derived estimates of UVA, UVB and temperature and relative humidity. Replication models were undertaken using comparable data for England and Italy. RESULTS: The mortality rate ratio (MRR) in the USA falls by 29% [95% confidence interval (CI) 40% to 15%) per 100 kJ m-2 increase in mean daily UVA. We replicated this in independent studies in Italy and England and estimate a pooled decline in MRR of 32% (95% CI 48% to 12%) per 100 kJ m-2 across the three studies. CONCLUSIONS: Our analysis suggests that higher ambient UVA exposure is associated with lower COVID-19-specific mortality. Further research on the mechanism may indicate novel treatments. Optimized UVA exposure may have population health benefits.

Low-dimensional nano-patterned surface fabricated by direct-write UV-chemically induced geometric inscription technique.

We investigate a nano-patterning process which creates reproducible periodic surface topological features that range in size from ∼100 µm to ∼20 µm. Specifically, we have fabricated multi-layered thin films consisting of germanium/silicon strata on a planar substrate, with each layer having nanometers thickness. The material processing exploits focused 244 nm ultra-violet laser light and an opto-mechanical setup typically applied to the inscription of fiber gratings, and is based upon the well-known material compaction interaction of ultra-violet light with germanium oxides. We show this process can be extended to create arrays of metal nano-antennas by adding a metal overlay to the thin film. This results in arrays with dimensions that span nanometer- to centimeter-length scales. Also, each nano-antenna consists of "nano-blocks." Experimental data are presented that show the UV irradiance dosage used to create these metal nanostructures on D-shaped optical fibers has a direct relationship to their transmission spectral characteristics as plasmonic devices.

Novel thermal annealing methodology for permanent tuning polymer optical fiber Bragg gratings to longer wavelengths.

The Bragg wavelength of a polymer optical fiber Bragg grating can be permanently shifted by utilizing the thermal annealing method. In all the reported fiber annealing cases, the authors were able to tune the Bragg wavelength only to shorter wavelengths, since the polymer fiber shrinks in length during the annealing process. This article demonstrates a novel thermal annealing methodology for permanently tuning polymer optical fiber Bragg gratings to any desirable spectral position, including longer wavelengths. Stretching the polymer optical fiber during the annealing process, the period of Bragg grating, which is directly related with the Bragg wavelength, can become permanently longer. The methodology presented in this article can be used to multiplex polymer optical fiber Bragg gratings at any desirable spectral position utilizing only one phase-mask for their photo-inscription, reducing thus their fabrication cost in an industrial setting.

Long-term adverse effects of paracetamol - a review.

Paracetamol (acetaminophen) is the most commonly used drug in the world, with a long record of use in acute and chronic pain. In recent years, the benefits of paracetamol use in chronic conditions has been questioned, notably in the areas of osteoarthritis and lower back pain. Over the same period, concerns over the long-term adverse effects of paracetamol use have increased, initially in the field of hypertension, but more recently in other areas as well. The evidence base for the adverse effects of chronic paracetamol use consists of many cohort and observational studies, with few randomized controlled trials, many of which contradict each other, so these studies must be interpreted with caution. Nevertheless, there are some areas where the evidence for harm is more robust, and if a clinician is starting paracetamol with the expectation of chronic use it might be advisable to discuss these side effects with patients beforehand. In particular, an increased risk of gastrointestinal bleeding and a small (~4 mmHg) increase in systolic blood pressure are adverse effects for which the evidence is particularly strong, and which show a degree of dose dependence. As our estimation of the benefits decreases, an accurate assessment of the harms is ever more important. The present review summarizes the current evidence on the harms associated with chronic paracetamol use, focusing on cardiovascular disease, asthma and renal injury, and the effects of in utero exposure.

Attending a social event and consuming alcohol is associated with changes in serum microRNA: a before and after study in healthy adults.

PURPOSE: Circulating microRNAs represent a reservoir for biomarker discovery. Our objective was to profile the change in human circulating microRNA associated with recreational use of alcohol at a social event. MATERIAL AND METHODS: Blood was collected from healthy volunteers (N = 16) before and after recreational consumption of alcohol (ethanol). Biochemistry, hematology and ethanol measurements were performed. The change in the serum small RNA fraction was quantified by RNA sequencing. RESULTS: Blood ethanol was undetectable at study entry in all subjects [<10 mg/dL]. After consuming alcohol the median concentration was 89 mg/dL [IQR: 71-138. Min-max 20-175]. There were no changes in biochemistry and hematology parameters. Serum RNA sequencing identified 1371 small RNA species (1305 microRNAs). There were significant increases [adjusted p-value <0.05, fold increase 2 or more] in 265 microRNAs, around a fifth of the total [median fold increase 2.3 [IQR: 2.1-2.5; Max: 3.7]]. miR-185-5p decreased following alcohol exposure [adjusted p-value <0.05, fold decrease 2 or more]. CONCLUSIONS: The microRNA composition of human serum is dynamic and environmental factors may have a significant impact. Within its context of use the fold change 'signal' of a microRNA must be large enough to negate the risk of false results due to background 'noise'.

Polymer optical fiber Bragg grating inscription with a single UV laser pulse.

We experimentally demonstrate the first polymer optical fiber Bragg grating inscribed with only one krypton fluoride laser pulse. The device has been recorded in a single-mode poly(methyl methacrylate) optical fiber, with a core doped with benzyl dimethyl ketal for photosensitivity enhancement. One laser pulse with a duration of 15 ns, which provide energy density of 974 mJ/cm2, is adequate to introduce a refractive index change of 0.74×10-4 in the fiber core. After the exposure, the reflectivity of the grating increases for a few minutes following a second order exponential saturation. The produced Bragg grating structure rejects 17.9 dB transmitted power, thus providing 98.4% reflectivity, which is well suited for sensing applications. In addition, we report the importance of the fiber thermal treatment before or after the inscription, showing its effects on the lifetime and quality of the grating structures. Optimizing the irradiation conditions and the material chemical composition, a higher refractive index change in the fiber core is feasible. This demonstration significantly improves the potential for commercial exploitation of the technology.

Real-time kinetic binding studies at attomolar concentrations in solution phase using a single-stage opto-biosensing platform based upon infrared surface plasmons.

Here we present a new generic opto-bio-sensing platform combining immobilised aptamers on an infrared plasmonic sensing device generated by nano-structured thin film that demonstrates amongst the highest index spectral sensitivities of any optical fibre sensor yielding on average 3.4 × 104 nm/RIU in the aqueous index regime (with a figure of merit of 330) This offers a single stage, solution phase, atto-molar detection capability, whilst delivering real-time data for kinetic studies in water-based chemistry. The sensing platform is based upon optical fibre and has the potential to be multiplexed and used in remote sensing applications. As an example of the highly versatile capabilities of aptamer based detection using our platform, purified thrombin is detected down to 50 attomolar concentration using a volume of 1mm3 of solution without the use of any form of enhancement technique. Moreover, the device can detect nanomolar levels of thrombin in a flow cell, in the presence of 4.5% w/v albumin solution. These results are important, covering all concentrations in the human thrombin generation curve, including the problematic initial phase. Finally, selectivity is confirmed using complementary and non-complementary DNA sequences that yield performances similar to those obtained with thrombin.

Hand eczema and steroid-refractory chronic hand eczema in general practice: prevalence and initial treatment.

BACKGROUND: The self-reported annual prevalence of hand eczema (HE) in adults is about 10%. Incidence and prevalence data for HE, chronic HE (CHE) and steroid-refractory CHE (SR-CHE) in physician-attended populations are lacking. OBJECTIVES: To estimate the prevalences of HE, CHE and SR-CHE in a primary-care population using a cross-sectional design; and to estimate the incidence of each and describe initial therapy using a cohort approach. METHODS: The population was all patients in the Clinical Practice Research Datalink for 2000-10, 2005-10 and 2010-11. HE was defined as any of 12 diagnoses (six specific to the hand, six for contact dermatitis). HE became CHE if any of these 12, or three additional diagnoses, occurred 90-365 days after the first HE, and if the patient was prescribed at least one course of potent topical steroids. A patient with CHE was classified as having SR-CHE if they were (i) referred to a dermatologist and/or (ii) prescribed phototherapy, systemic immunomodulators, oral corticosteroids, alitretinoin or acitretin. RESULTS: The 1-year adult prevalence of HE was 0·4%. The period prevalences of SR-CHE for 1, 5 and 10 years in adults were 0·008%, 0·036% and 0·072%, respectively; lifetime estimates were 0·071%, 0·080%, 0·098%. About one-half of cases of CHE were steroid refractory. All conditions were more common in female than in male patients. One-third of HE diagnoses were specific for the hand, the remainder were for contact dermatitis. The majority (62%) of newly diagnosed patients with HE were not prescribed treatment in the 12 months after diagnosis. CONCLUSIONS: Although the prevalence of HE could be 2-3 times higher than reported herein, the proportion of adults seeking medical care for HE is a fraction of those who self-report HE. SR-CHE is rare.

Influenza-attributable burden in United Kingdom primary care.

Influenza is rarely laboratory-confirmed and the outpatient influenza burden is rarely studied due to a lack of suitable data. We used the Clinical Practice Research Datalink (CPRD) and surveillance data from Public Health England in a linear regression model to assess the number of persons consulting UK general practitioners (GP episodes) for respiratory illness, otitis media and antibiotic prescriptions attributable to influenza during 14 seasons, 1995-2009. In CPRD we ascertained influenza vaccination status in each season and risk status (conditions associated with severe influenza outcomes). Seasonal mean estimates of influenza-attributable GP episodes in the UK were 857 996 for respiratory disease including 68 777 for otitis media, with wide inter-seasonal variability. In an average season, 2·4%/0·5% of children aged <5 years and 1·3%/0·1% of seniors aged ⩾75 years had a GP episode for respiratory illness attributed to influenza A/B. Two-thirds of influenza-attributable GP episodes were estimated to result in prescription of antibiotics. These estimates are substantially greater than those derived from clinically reported influenza-like illness in surveillance programmes. Because health service costs of influenza are largely borne in general practice, these are important findings for cost-benefit assessment of influenza vaccination programmes.

Time-dependent variation of fiber Bragg grating reflectivity in PMMA-based polymer optical fibers.

In this Letter, we investigate the effects of viscoelasticity on both the strength and resonance wavelength of two fiber Bragg gratings (FBGs) inscribed in microstructured polymer optical fiber (mPOF) made of undoped PMMA. Both FBGs were inscribed under a strain of 1% in order to increase the material photosensitivity. After the inscription, the strain was released, and the FBGs spectra were monitored. We initially observed a decrease of the reflection down to zero after which it began to increase. After that, strain tests were carried out to confirm the results, and finally the gratings were monitored for a further 120 days, with a stable reflection response being observed beyond 50 days.

Imaging of cardiovascular risk in patients with Turner's syndrome.

Turner's syndrome is a disorder defined by an absent or structurally abnormal second X chromosome and affects around 1 in 2000 newborn females. The standardised mortality ratio in Turner's syndrome is around three-times higher than in the general female population, mainly as a result of cardiovascular disorders. Most striking is the early age at which Turner's syndrome patients develop the life-threatening complications of cardiovascular disorders compared to the general population. The cardiovascular risk stratification in Turner's syndrome is challenging and imaging is not systematically used. The aim of this article is to review cardiovascular risks in this group of patients and discuss a systematic imaging approach for early identification of cardiovascular disorders in these patients.

Photosensitivity mechanism of undoped poly(methyl methacrylate) under UV radiation at 325 nm and its spatial resolution limit.

In this Letter, we provide evidence suggesting that the main photosensitive mechanism of an undoped poly(methyl methacrylate)-based microstructured optical fiber under UV radiation at 325 nm is a competitive process of both photodegradation and polymerization. We found experimentally that increasing strain during photo-inscription leads to an increased photosensitivity, which is evidence of photodegradation. Likewise, refractive index change in the fiber was measured to be positive, which provides evidence for further polymerization of the material. Finally, we relate the data obtained to the spatial recording resolution of the samples.

Physical characteristics of localized surface plasmons resulting from nano-scale structured multi-layer thin films deposited on D-shaped optical fiber.

Novel surface plasmonic optical fiber sensors have been fabricated using multiple coatings deposited on a lapped section of a single mode fiber. UV laser irradiation processing with a phase mask produces a nano-scaled surface relief grating structure resembling nano-wires. The resulting individual corrugations produced by material compaction are approximately 20 µm long with an average width at half maximum of 100 nm and generate localized surface plasmons. Experimental data are presented that show changes in the spectral characteristics after UV processing, coupled with an overall increase in the sensitivity of the devices to surrounding refractive index. Evidence is presented that there is an optimum UV dosage (48 joules) over which no significant additional optical change is observed. The devices are characterized with regards to change in refractive index, where significantly high spectral sensitivities in the aqueous index regime are found, ranging up to 4000 nm/RIU for wavelength and 800 dB/RIU for intensity.

Highly photosensitive polymethyl methacrylate microstructured polymer optical fiber with doped core.

In this Letter, we report the fabrication of a highly photosensitive, microstructured polymer optical fiber using benzyl dimethyl ketal as a dopant, as well as the inscription of a fiber Bragg grating in the fiber. A refractive index change in the core of at least 3.2×10(-4) has been achieved, providing a grating with a strong transmission rejection of -23 dB with an inscription time of only 13 min. The fabrication method has a big advantage compared to doping step index fiber since it enables doping of the fiber without using extra dopants to compensate for the index reduction in the core introduced by the photosensitive agent.

Improvement in symptoms of peripheral arterial disease with sildenafil therapy.

A 57-year-old man presented with symptoms of intermittent claudication and was diagnosed with peripheral arterial disease. He was advised to stop smoking and start a walking programme. He had a background history of hypercholesterolaemia and erectile dysfunction, for which he was taking simvastatin and phosphodiesterase type-5 inhibitor sildenafil, respectively. After starting his exercise programme, he noted that his walking distance was more than doubled on the mornings after taking sildenafil, and he has been using sildenafil primarily for shopping trips since that time. Although this single-patient self-experiment has the potential for placebo confounding, the patient was not led to expect this benefit, and there is evidence that reduced nitric oxide bioactivity plays an important role in the pathophysiology of peripheral arterial disease. Given the biological plausibility of this effect, we feel that a randomised, blinded and placebo-controlled clinical study is warranted to confirm the benefit of phosphodiesterase type-5 inhibitors in peripheral arterial disease.

Arbitrary real-time three-dimensional corporal object sensing and reconstruction scheme.

A real-time three-dimensional (3D) object sensing and reconstruction scheme is presented that can be applied on any arbitrary corporeal shape. Operation is demonstrated on several calibrated objects. The system uses curvature sensors based upon in-line fiber Bragg gratings encapsulated in a low-temperature curing synthetic silicone. New methods to quantitatively evaluate the performance of a 3D object-sensing scheme are developed and appraised. It is shown that the sensing scheme yields a volumetric error of 1% to 9%, depending on the object.

Characterizing femtosecond laser inscribed Bragg grating spectra.

We present numerical modeling based on a combination of the Bidirectional Beam Propagation Method and Finite Element Method that completely describes the wavelength spectra of point by point femtosecond laser inscribed fiber Bragg gratings, showing excellent agreement with experiment. We have investigated the dependence of different spectral parameters such as insertion loss, all dominant cladding and ghost modes and their shape relative to the position of the fiber Bragg grating in the core of the fiber. Our model is validated by comparing model predictions with experimental data and allows for predictive modeling of the gratings. We expand our analysis to more complicated structures, where we introduce symmetry breaking; this highlights the importance of centered gratings and how maintaining symmetry contributes to the overall spectral quality of the inscribed Bragg gratings. Finally, the numerical modeling is applied to superstructure gratings and a comparison with experimental results reveals a capability for dealing with complex grating structures that can be designed with particular wavelength characteristics.

Endothelial ET(B) limits vascular remodelling and development of pulmonary hypertension during hypoxia.

BACKGROUND: We hypothesised that the potential protective effects of endothelial ET(B) are important in limiting pulmonary vascular muscularisation, vasoconstriction and the development of pulmonary arterial hypertension in response to hypoxia. METHODS: EC-specific ET(B) knockout mice (EC ET(B)(-/-)) and control mice (ET(B)(f/f)) were subjected to hypobaric hypoxic (10% FiO2) or normoxic conditions for 14 days before assessment of right ventricular pressure and pulmonary vascular morphology and function. RESULTS: During normoxia, no difference in right ventricular pressure was detected between EC ET(B)(-/-) (23.7 +/- 1.7 mm Hg) and ET(B)(f/f) mice (20.2 +/- 1.5 mm Hg). Hypoxia induced an exaggerated increase in right ventricular pressure in EC ET(B)(-/-) mice (34.4 +/- 1.2 mm Hg vs. 24.6 +/- 1.4 mm Hg), accompanied by an increase in right ventricular mass. No effect was observed in ET(B)(f/f) mice. Endothelin-1 constricted pulmonary arteries from both groups, although maximum response was similar irrespective of inspired oxygen or genotype. Hypoxia increased the percentage of muscularised vessels in both groups of mice, but the percentage increase was significantly greater in EC ET(B)(-/-) mice. CONCLUSIONS: The potential protective effects of endothelial ET(B) are important in limiting pulmonary vascular muscularisation and the development of pulmonary arterial hypertension in response to hypoxia.