Radiative transfer of energy at the nanometre length scale is of great importance to a variety of technologies including heat-assisted magnetic recording, near-field thermophotovoltaics and ...lithography. Although experimental advances have enabled elucidation of near-field radiative heat transfer in gaps as small as 20-30 nanometres (refs 4-6), quantitative analysis in the extreme near field (less than 10 nanometres) has been greatly limited by experimental challenges. Moreover, the results of pioneering measurements differed from theoretical predictions by orders of magnitude. Here we use custom-fabricated scanning probes with embedded thermocouples, in conjunction with new microdevices capable of periodic temperature modulation, to measure radiative heat transfer down to gaps as small as two nanometres. For our experiments we deposited suitably chosen metal or dielectric layers on the scanning probes and microdevices, enabling direct study of extreme near-field radiation between silica-silica, silicon nitride-silicon nitride and gold-gold surfaces to reveal marked, gap-size-dependent enhancements of radiative heat transfer. Furthermore, our state-of-the-art calculations of radiative heat transfer, performed within the theoretical framework of fluctuational electrodynamics, are in excellent agreement with our experimental results, providing unambiguous evidence that confirms the validity of this theory for modelling radiative heat transfer in gaps as small as a few nanometres. This work lays the foundations required for the rational design of novel technologies that leverage nanoscale radiative heat transfer.
Thermal radiative emission from a hot surface to a cold surface plays an important role in many applications, including energy conversion, thermal management, lithography, data storage and thermal ...microscopy. Recent studies on bulk materials have confirmed long-standing theoretical predictions indicating that when the gap between the surfaces is reduced to tens of nanometres, well below the peak wavelength of the blackbody emission spectrum, the radiative heat flux increases by orders of magnitude. However, despite recent attempts, whether such enhancements can be obtained in nanoscale dielectric films thinner than the penetration depth of thermal radiation, as suggested by theory, remains experimentally unknown. Here, using an experimental platform that comprises a heat-flow calorimeter with a resolution of about 100 pW (ref. 7), we experimentally demonstrate a dramatic increase in near-field radiative heat transfer, comparable to that obtained between bulk materials, even for very thin dielectric films (50-100 nm) when the spatial separation between the hot and cold surfaces is comparable to the film thickness. We explain these results by analysing the spectral characteristics and mode shapes of surface phonon polaritons, which dominate near-field radiative heat transport in polar dielectric thin films.
Resistin is a cytokine related with inflammation and ischemic heart disease. Physical activity (PA) prevents chronic inflammation and ischemic heart disease. We studied the relationship of serum ...concentration of resistin with HDL cholesterol, a known biomarker of PA, and with different measures of PA, in a large sample of the general adult population in the Canary Islands.
Cross-sectional study of 6636 adults recruited randomly. We analyzed the correlation of resistin and HDL cholesterol with PA (as metabolic equivalent level MET), and fitted the results with linear and logistic regression models using adjustment for age, alcohol consumption and smoking.
Mean resistin level was higher in women (p<0.001), correlated inversely with age, HDL cholesterol (p<0.001) and alcohol consumption (p<0.001 in men), and correlated directly with smoking (p<0.001). Resistin correlated inversely with the duration of leisure time PA (p<0.001), leisure time MET (p<0.001) and moderate leisure time PA (p<0.001), with some differences between sexes. Men (OR = 0.78 0.61-0.99; p<0.05) and women (OR = 0.75 0.61-0.92; p<0.01) in the upper quintile of leisure time PA had a lower risk of elevated resistin. In contrast, a high degree of sedentarism was associated with an increased risk elevated resistin in women (OR = 1.24 1.04-1.47; p<0.05 and in men (OR = 1.40 1.01-1.82; p<0.05).
In our sample of the general population, resistin was inversely associated with measures and levels of PA and HDL cholesterol. The association of resistin with PA was stronger than the association of HDL cholesterol with PA, making resistin a potentially useful biomarker of PA.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Radiative heat transfer in Ångström- and nanometre-sized gaps is of great interest because of both its technological importance and open questions regarding the physics of energy transfer in this ...regime. Here we report studies of radiative heat transfer in few Å to 5 nm gap sizes, performed under ultrahigh vacuum conditions between a Au-coated probe featuring embedded nanoscale thermocouples and a heated planar Au substrate that were both subjected to various surface-cleaning procedures. By drawing on the apparent tunnelling barrier height as a signature of cleanliness, we found that upon systematically cleaning via a plasma or locally pushing the tip into the substrate by a few nanometres, the observed radiative conductances decreased from unexpectedly large values to extremely small ones-below the detection limit of our probe-as expected from our computational results. Our results show that it is possible to avoid the confounding effects of surface contamination and systematically study thermal radiation in Ångström- and nanometre-sized gaps.
Serum resistin is a pro-inflammatory cytokine that has been described as a risk factor associated with mortality in several clinical sets including type 2 diabetes. Mortality studies in the general ...population are needed to find out the risk of death associated to this cytokine. In a follow-up study of a cohort of adult population (n = 6636) in Spain over a period of fifteen years (447 deaths/102,255 person-years), serum resistin measurements and death records were obtained. The risks of all-cause deaths, and deaths from cardiovascular and oncological diseases were estimated. Hazard ratios (HR) and its confidence intervals (CI) were calculated using multivariable Cox models, adjusting the effect of 11 traditional risk factors. The risk of all-cause mortality among participants exposed to the highest quintile of resistin was always higher than among those in the lowest quintile (HR varied between 1.55 when smoking was the adjusted factor 95% CI 1.17-2.05, and 1.68 when the adjusted factor was physical activity 95% CI 1.27-2.21). The maximally adjusted model, accounting for the effect of all traditional factors, corroborated this higher risk of all-cause mortality among people in the highest resistin quintile (HR = 1.52; 95% CI 1.13-2.05). The effect of resistin was even higher for cardiovascular deaths (HR = 2.14; 95% CI 1.13-4.06), being exceeded only by suffering diabetes (HR = 3.04; 95% CI 1.98-4.69) or previous acute coronary syndrome (HR = 3.67; 95% CI 2.18-6.18). This findings corroborate the role of resistin as a risk factor for all-cause (and cardiovascular) death in the general population.
To analyze the trend of lower extremity major amputations (MA) among patients with type 2 diabetes mellitus (T2DM) in the Regions of Spain from year 2001 until 2015.
Descriptive study of 40,392 MA. ...Data were obtained from the national hospital discharge database in patients with T2DM. The incidence rate was calculated in each Region, in addition to the incidence ratios (IR) between annual incidence and incidence of the year 2001. The length of hospital stay and mortality risks were analyzed using regression models adjusted for sex, age and smoking.
The major amputations incidence rate per 100,000 person-years was 0.48 in Spain; Canary Islands showed the highest incidence (0.81). The trend was a slight decrease or stability of the incidence in all Regions except in the Canary Islands (IR
= 2.0 CI95% = 1.5, 2.6) and in Madrid (IR
= 0.1 CI95% = 0.1, 0.2). Mortality after major amputations was 10% in Spain; Cantabria suffered the highest risk of death 1.7 (CI95% = 1.4; 2.1), p < 0.001 and La Rioja the lowest risk (0.5 CI95% = 0.2; 0.9; p = 0.026). The longest hospital stay was registered in the Canary Islands (CI95% = 11.4;13.3, p < 0.001), and the shortest in the Valencian Community (CI95% = - 7.3; - 5.8), p < 0.001).
MA in T2DM followed a growing trend in the Canary Islands, which diverged from the downward trend in Spain. The variability of mortality and hospital stay, suggest to review the clinical management in some Regions. Sudden incidence decrease in Madrid suggests checking the record procedures of hospital discharges.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The path to sustainable small-scale fisheries (SSF) is based on multiple learning processes that must transcend generational changes. To understand young leaders from communities with sustainable SSF ...management practices in Mexico, we used in-depth interviews to identify their shared motivations and perceptions for accepting their fishing heritage. These possible future decision-makers act as agents of change due to their organizational and technological abilities. However, young people are currently at a crossroads. Many inherited a passion for the sea and want to improve and diversify the fishing sector, yet young leaders do not want to accept a legacy of complicated socioenvironmental conditions that can limit their futures. These future leaders are especially concerned by the uncertainty caused by climate change. If fishing and generational change are not valued in planning processes, the continuity of fisheries, the success of conservation actions, and the lifestyles of young fishers will remain uncertain.
Graphical abstract
Background:
To analyze the incidence and mortality of cerebrovascular diseases (CeVD) in Spain from 2001 to 2015.
Methods:
Retrospective study of hospital incidence, hospital case fatality and ...population mortality, with records from the Spanish Government Statistics. Days of hospital stay and risk of death (RD) during admission were estimated adjusting for age, sex, first stroke (FS), atrial fibrillation (AF), diabetes, hypertension, and smoking.
Results:
There were 1,662,487 stroke cases older than 15 years of age admitted to hospital (1,096,748 FS), with a national incidence = 291/105 in this period (Murcia maximum (367/105), Canary Islands minimum (238/105)). Population mortality (−50%) decreased while case fatality remained stable (−3%), despite the increase in the age of patients (+2.29 years) and the incidence (+25%). Canary Islands had the youngest patients (−3.5 years for men and −6 years for women) and the longest hospital stay (+5.1 days). Andalusia (odds ratio (OR) = 1.21 (1.19; 1.22)) and the Canaries (OR = 1.18 (1.15; 1.21)) had the highest RD. The factors associated to the highest increases in RD were FS (OR = 1.34 (95% confidence interval (CI) = 1.33–1.35)) and AF (OR = 1.30 (95% CI = 1.29–1.31)).
Conclusion:
Population mortality due to CeVD was reduced by half in Spain between 2001 and 2015, but hospital incidence increased. Andalusia and the Canary Islands had the highest RD in the country. These islands presented the lowest incidence, but their patients were younger, and their hospital stay longer. FS and AF were the factors associated with a higher RD.
Very recently it has been predicted that the far-field radiative heat transfer between two macroscopic systems can largely overcome the limit set by Planck’s law if one of their dimensions becomes ...much smaller than the thermal wavelength (λTh ≈ 10 μm at room temperature). To explore the ultimate limit of the far-field violation of Planck’s law, here we present a theoretical study of the radiative heat transfer between two-dimensional (2D) materials. We show that the far-field thermal radiation exchanged by two coplanar systems with a one-atom-thick geometrical cross section can be more than 7 orders of magnitude larger than the theoretical limit set by Planck’s law for blackbodies and can be comparable to the heat transfer of two parallel sheets at the same distance. In particular, we illustrate this phenomenon with different materials such as graphene, where the radiation can also be tuned by a external gate, and single-layer black phosphorus. In both cases the far-field radiative heat transfer is dominated by TE-polarized guiding modes, and surface plasmons play no role. Our predictions provide a new insight into the thermal radiation exchange mechanisms between 2D materials.
To detect modifiable factors and target populations associated with uncontrolled type 2 diabetes in primary care.
Retrospective cross-sectional descriptive study.
Health center of Barranco Grande, ...Tenerife.
Random selection of patients with DM2 attended by 12 family doctors and 12 nurses.
In addition to the control of DM2, sociodemographic, clinical data, lifestyle and follow-up of preventive and therapeutic measures were obtained. After bivariate analysis, a multilevel multivariate model was adjusted by taking the quota of patients assisted by each physician as a second-level mixed-effect variable and the rest as first-level variables.
587 patients were recruited (46.5% female), treated with 1.9-1.1 antidiabetic drugs, with 4.1% therapeutic non-compliance, and suffering 13.8% therapeutic inertia. 23.7% showed poor DM2 control, being significantly worse (p<0.05) in male sex, age <65 years, evolution DM2 -5 years, work-active, upper-middle studies, inadequate diet, metabolic syndrome, ratio TG/HDL-3, complications of DM2, Charlson index<5, nursing visits <3/year, without ECG in the last year, and more drugs prescribed for DM2. The doctor-nurse quota was associated with poor control with an intraclass coefficient of 0.01.
Men under 65 years of age with DM2 evolution longer than 5 years are a target population to intensify interventions. Therapeutic non-compliance, inadequate diet, lack of adherence protocols and ratio TG/HDL>3 are the main modifiable factors on which to intervene. The association of the doctor-nurse quota with the control of DM2 is weak, probably due to adequate follow-up of preventive programs.
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