2,083 research outputs found
Hybrid photonic crystal lasers
Energy efficient Wavelength Division Multiplexing (WDM) is the key to satisfying the future bandwidth requirements of datacentres. As the silicon photonics platform is regarded the only technology able to meet the required power and cost efficiency levels, the development of silicon photonics compatible narrow linewidth lasers is now crucial. We discuss the requirements for such laser systems and report the experimental demonstration of a compact uncooled external-cavity mW-class laser architecture with a tunable Si Photonic Crystal resonant reflector, suitable for direct Frequency Modulation.Postprin
Wavelength stability in a hybrid photonic crystal laser through controlled nonlinear absorptive heating in the reflector
The need for miniaturized, fully integrated semiconductor lasers has stimulated significant research efforts into realizing unconventional configurations that can meet the performance requirements of a large spectrum of applications, ranging from communication systems to sensing. We demonstrate a hybrid, silicon photonics-compatible photonic crystal (PhC) laser architecture that can be used to implement cost-effective, high-capacity light sources, with high side-mode suppression ratio and milliwatt output output powers. The emitted wavelength is set and controlled by a silicon PhC cavity-based reflective filter with the gain provided by a III–V-based reflective semiconductor optical amplifier (RSOA). The high power density in the laser cavity results in a significant enhancement of the nonlinear absorption in silicon in the high Q-factor PhC resonator. The heat generated in this manner creates a tuning effect in the wavelength-selective element, which can be used to offset external temperature fluctuations without the use of active cooling. Our approach is fully compatible with existing fabrication and integration technologies, providing a practical route to integrated lasing in wavelength-sensitive schemes
Oxidative stress and non-alcoholic fatty liver disease: effects of omega-3 fatty acid supplementation
Aging is a complex phenomenon characterized by the progressive loss of tissue and organ function. The oxidative-stress theory of aging postulates that age-associated functional losses are due to the accumulation of ROS-induced damage. Liver function impairment and non-alcoholic fatty liver disease (NAFLD) are common among the elderly. NAFLD can progress to non-alcoholic steatohepatitis (NASH) and evolve to hepatic cirrhosis or hepatic carcinoma. Oxidative stress, lipotoxicity, and inflammation play a key role in the progression of NAFLD. A growing body of evidence supports the therapeutic potential of omega-3 polyunsaturated fatty acids (n-3 PUFA), mainly docosahaexenoic (DHA) and eicosapentaenoic acid (EPA), on metabolic diseases based on their antioxidant and anti-inflammatory properties. Here, we performed a systematic review of clinical trials analyzing the efficacy of n-3 PUFA on both systemic oxidative stress and on NAFLD/NASH features in adults. As a matter of fact, it remains controversial whether n-3 PUFA are effective to counteract oxidative stress. On the other hand, data suggest that n-3 PUFA supplementation may be effective in the early stages of NAFLD, but not in patients with more severe NAFLD or NASH. Future perspectives and relevant aspects that should be considered when planning new randomized controlled trials are also discussed
Wavelength stability in a hybrid photonic crystal laser through controlled nonlinear absorptive heating in the reflector
This work was supported by the Science Foundation Ireland under Grants SFI12/RC/2276 and 16/ERCS/3838, Engineering and Physical Sciences Research Council (EPSRC) (doctoral grant EP/L505079/1 and equipment grant EP/L017008/1); European Research Council (ERC) (Starting Grant 337508); and Scottish Enterprise.The need for miniaturized, fully integrated semiconductor lasers has stimulated significant research efforts into realizing unconventional configurations that can meet the performance requirements of a large spectrum of applications, ranging from communication systems to sensing. We demonstrate a hybrid, silicon photonics-compatible photonic crystal (PhC) laser architecture that can be used to implement cost-effective, high-capacity light sources, with high side-mode suppression ratio and milliwatt output output powers. The emitted wavelength is set and controlled by a silicon PhC cavity-based reflective filter with the gain provided by a III–V-based reflective semiconductor optical amplifier (RSOA). The high power density in the laser cavity results in a significant enhancement of the nonlinear absorption in silicon in the high Q-factor PhC resonator. The heat generated in this manner creates a tuning effect in the wavelength-selective element, which can be used to offset external temperature fluctuations without the use of active cooling. Our approach is fully compatible with existing fabrication and integration technologies, providing a practical route to integrated lasing in wavelength-sensitive schemes.Publisher PDFPeer reviewe
TyG Index change is more determinant for forecasting type 2 diabetes onset than weight gain
Abstract: The risk of type 2 diabetes associated with obesity appears
to be influenced by other metabolic abnormalities, and there is controversy
about the harmless condition of the metabolically healthy obese
(MHO) state. The aim of this study is to assess the risk of diabetes and
the impact of changes in weight and in triglyceride-glucose index (TyG
index), according to the metabolic health and obesity states.
We analyzed prospective data of the Vascular Metabolic CUN
cohort, a population-based study among a White European population
(mean follow-up, 8.9 years). Incident diabetes was assessed in 1923
women and 3016 men with a mean age at baseline of 55.33 13.68 and
53.78 12.98 years old.
A Cox proportional-hazard analysis was conducted to estimate the
hazard ratio (HR) of diabetes on metabolically healthy nonobese
(MHNO), metabolically healthy obese, metabolically unhealthy nonobese
(MUNO), and metabolically unhealthy obese (MUO). A continuous
standardized variable (z-score) was derived to compute the HR
for diabetes per 1-SD increment in the body mass index (BMI) and the
TyG index.
MHO, MUNO, and MUO status were associated with the development
of diabetes, HR of 2.26 (95% CI: 1.25–4.07), 3.04 (95% CI: 1.69–
5.47), and 4.04 (95% CI: 2.14–7.63), respectively. MUNO individuals
had 1.82 greater risk of diabetes compared to MHO subjects (95% CI:
1.04–3.22). The HRs for incident diabetes per 1-SD increment in BMI
and TyG indexes were 1.23 (95% CI: 1.04–1.44) and 1.54 (95% CI:
1.40–1.68). The increase in BMI did not raise the risk of developing
diabetes among metabolically unhealthy subjects, whereas increasing
the TyG index significantly affect the risk in all metabolic health
categories.
Metabolic health is more important determinant for diabetes onset
than weight gain. The increase in weight does not raise the risk of
developing diabetes among metabolically unhealthy subjects
Intensive care unit discharge to the ward with a tracheostomy cannula as a risk factor for mortality: A prospective, multicenter propensity analysis
To analyze the impact of decannulation before intensive care unit
discharge on ward survival in nonexperimental conditions. DESIGN: Prospective,
observational survey. SETTING: Thirty-one intensive care units throughout Spain.
PATIENTS: All patients admitted from March 1, 2008 to May 31, 2008.
INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: At intensive care unit
discharge, we recorded demographic variables, severity score, and intensive care
unit treatments, with special attention to tracheostomy. After intensive care
unit discharge, we recorded intensive care unit readmission and hospital
survival. STATISTICS: Multivariate analyses for ward mortality, with Cox
proportional hazard ratio adjusted for propensity score for intensive care unit
decannulation. We included 4,132 patients, 1,996 of whom needed mechanical
ventilation. Of these, 260 (13%) were tracheostomized and 59 (23%) died in the
intensive care unit. Of the 201 intensive care unit tracheostomized survivors, 60
were decannulated in the intensive care unit and 141 were discharged to the ward
with cannulae in place. Variables associated with intensive care unit
decannulation (non-neurologic disease [85% vs. 64%], vasoactive drugs [90% vs.
76%], parenteral nutrition [55% vs. 33%], acute renal failure [37% vs. 23%], and
good prognosis at intensive care unit discharge [40% vs. 18%]) were included in a
propensity score model for decannulation. Crude ward mortality was similar in
decannulated and nondecannulated patients (22% vs. 23%); however, after
adjustment for the propensity score and Sabadell Score, the presence of a
tracheostomy cannula was not associated with any survival disadvantage with an
odds ratio of 0.6 [0.3-1.2] (p=.1). CONCLUSION: In our multicenter setting,
intensive care unit discharge before decannulation is not a risk factor
Evaluation of different bowel preparations for small bowel capsule endoscopy: a prospective, randomized, controlled study
To obtain an adequate view of the whole small
intestine during capsule endoscopy (CE) a clear liquid diet and overnight fasting
is recommended. However, intestinal content can hamper vision in spite of these
measures. Our aim was to evaluate tolerance and degree of intestinal cleanliness
during CE following three types of bowel preparation. PATIENTS AND METHODS: This
was a prospective, multicenter, randomized, controlled study. Two-hundred
ninety-one patients underwent one of the following preparations: 4 L of clear
liquids (CL) (group A; 92 patients); 90 mL of aqueous sodium phosphate (group B;
89 patients); or 4 L of a polyethylene glycol electrolyte solution (group C; 92
patients). The degree of cleanliness of the small bowel was classified by blinded
examiners according to four categories (excellent, good, fair or poor). The
degree of patient satisfaction, gastric and small bowel transit times, and
diagnostic yield were measured. RESULTS: The degree of cleanliness did not differ
significantly between the groups (P = 0.496). Interobserver concordance was fair
(k = 0.38). No significant differences were detected between the diagnostic
yields of the CE (P = 0.601). Gastric transit time was 35.7 +/- 3.7 min (group
A), 46.1 +/- 8.6 min (group B) and 34.6 +/- 5.0 min (group C) (P = 0.417).
Small-intestinal transit time was 276.9 +/- 10.7 min (group A), 249.7 +/- 13.1
min (group B) and 245.6 +/- 11.6 min (group C) (P = 0.120). CL was the best
tolerated preparation. Compliance with the bowel preparation regimen was lowest
in group C (P = 0.008). CONCLUSIONS: A clear liquid diet and overnight fasting is
sufficient to achieve an adequate level of cleanliness and is better tolerated by
patients than other forms of preparation
Healthy lifestyle and incidence of metabolic syndrome in the SUN cohort
We assessed the relationship between a healthy lifestyle and the subsequent risk of developing metabolic syndrome. The "Seguimiento Universidad de Navarra" (SUN) Project is a prospective cohort study, focused on nutrition, lifestyle, and chronic diseases. Participants (n = 10,807, mean age 37 years, 67% women) initially free of metabolic syndrome were followed prospectively for a minimum of 6 years. To evaluate healthy lifestyle, nine habits were used to derive a Healthy Lifestyle Score (HLS): Never smoking, moderate to high physical activity (>20 MET-h/week), Mediterranean diet (>= 4/8 adherence points), moderate alcohol consumption (women, 0.1-5.0 g/day; men, 0.1-10.0 g/day), low television exposure (1 h/day, and working at least 40 h/week. Metabolic syndrome was defined according to the harmonizing definition. The association between the baseline HLS and metabolic syndrome at follow-up was assessed with multivariable-adjusted logistic regressions. During follow-up, we observed 458 (4.24%) new cases of metabolic syndrome. Participants in the highest category of HLS adherence (7-9 points) enjoyed a significantly reduced risk of developing metabolic syndrome compared to those in the lowest category (0-3 points) (adjusted odds ratio (OR) = 0.66, 95% confidence interval (CI) = 0.47-0.93). Higher adherence to the Healthy Lifestyle Score was associated with a lower risk of developing metabolic syndrome. The HLS may be a simple metabolic health promotion tool
Isotemporal substitution of inactive time with physical activity and time in bed: cross-sectional associations with cardiometabolic health in the PREDIMEDPlus study
Background: This study explored the association between inactive time and measures of adiposity, clinical parameters, obesity, type 2 diabetes and metabolic syndrome components. It further examined the impact of reallocating inactive time to time in bed, light physical activity (LPA) or moderate-to-vigorous physical activity (MVPA) on cardio-metabolic risk factors, including measures of adiposity and body composition, biochemical parameters and blood pressure in older adults.
Methods: This is a cross-sectional analysis of baseline data from 2189 Caucasian men and women (age 55-75 years, BMI 27-40 Kg/m2) from the PREDIMED-Plus study (http://www.predimedplus.com/). All participants had ≥3 components of the metabolic syndrome. Inactive time, physical activity and time in bed were objectively determined using triaxial accelerometers GENEActiv during 7 days (ActivInsights Ltd., Kimbolton, United Kingdom). Multiple adjusted linear and logistic regression models were used. Isotemporal substitution regression modelling was performed to assess the relationship of replacing the amount of time spent in one activity for another, on each outcome, including measures of adiposity and body composition, biochemical parameters and blood pressure in older adults.
Results: Inactive time was associated with indicators of obesity and the metabolic syndrome. Reallocating 30 min per day of inactive time to 30 min per day of time in bed was associated with lower BMI, waist circumference and glycated hemoglobin (HbA1c) (all p-values < 0.05). Reallocating 30 min per day of inactive time with 30 min per day of LPA or MVPA was associated with lower BMI, waist circumference, total fat, visceral adipose tissue, HbA1c, glucose, triglycerides, and higher body muscle mass and HDL cholesterol (all p-values < 0.05).
Conclusions: Inactive time was associated with a poor cardio-metabolic profile. Isotemporal substitution of inactive time with MVPA and LPA or time in bed could have beneficial impact on cardio-metabolic health
Relationship between olive oil consumption and ankle-brachial pressure index in a population at high cardiovascular risk
The aim of this study was to ascertain the association between the consumption of different categories of edible olive oils (virgin olive oils and olive oil) and olive pomace oil and ankle-brachial pressure index (ABI) in participants in the PREDIMED-Plus study, a trial of lifestyle modification for weight and cardiovascular event reduction in individuals with overweight/obesity harboring the metabolic syndrome.
Methods: We performed a cross-sectional analysis of the PREDIMED-Plus trial. Consumption of any category of olive oil and olive pomace oil was assessed through a validated food-frequency questionnaire. Multivariable linear regression models were fitted to assess associations between olive oil consumption and ABI. Additionally, ABI ≤1 was considered as the outcome in logistic models with different categories of olive oil and olive pomace oil as exposure.
Results: Among 4330 participants, the highest quintile of total olive oil consumption (sum of all categories of olive oil and olive pomace oil) was associated with higher mean values of ABI (beta coefficient: 0.014, 95% confidence interval [CI]: 0.002, 0.027) (p for trend = 0.010). Logistic models comparing the consumption of different categories of olive oils, olive pomace oil and ABI ≤1 values revealed an inverse association between virgin olive oils consumption and the likelihood of a low ABI (odds ratio [OR] 0.73, 95% CI [0.56, 0.97]), while consumption of olive pomace oil was positively associated with a low ABI (OR 1.22 95% CI [1.00, 1.48]).
Conclusions: In a Mediterranean population at high cardiovascular risk, total olive oil consumption was associated with a higher mean ABI. These results suggest that olive oil consumption may be beneficial for peripheral artery disease prevention, but longitudinal studies are needed
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