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Metal nanowires can emit coherent polarized thermal radiation, work as uncooled bolometers, and provide localized heating. In this paper, we engineer the temperature dynamics of electrically driven Pt nanoheaters on a silicon-on-insulator substrate. We present three designs and we electrically characterize and model their thermal impedance in the frequency range from 3Hz to 3MHz. Finally, we show a temperature modulation of 300K while consuming less than 5 mW of power, up to a frequency of 1.3 MHz. This result can lead to significant advancements in thermography and absorption spectroscopy. [ABSTRACT FROM AUTHOR]

This paper presents how reducing the width and length of a bolometer’s sensing core affects its performance. Bolometer devices made of thin films of platinum with various lateral dimensions—widths ranging from 300 nm to 4 μm and lengths ranging from 300 nm to 19 μm were tested. Some are significantly smaller in size than the wavelengths they are exposed to, coming from a blackbody source with a λpeak of 2.74 μm. A resonance effect is revealed for samples of specific dimensions, where the performance is enhanced. Further, a strong increase in responsivity appears when the sample’s width is narrowed, whereas specific detectivity remains independent of any change in dimensions. We believe that some of these features are due to plasmonic effects, which may explain the high performance reached by smaller samples. It seems that graphene could be subject to similar geometrical effects to our thin-film bolometers. [ABSTRACT FROM AUTHOR]

Objectives The importance of the left atrial appendage (LAA) on left atrial (LA) hemodynamics is unknown. We sought to evaluate the effect of LAA percutaneous closure (LAAPC) on left atrial remodeling in patients with paraxysmal atrial fibrillation (AF) and permanent AF. Methods All patients refered for LAAPC with Amplatzer Cardiac Plug (ACP) and Watchman device were enrolled. Cardiac computed tomography (CT) for LA volume measurement and transthoracic echocardiography (TTE) for diastolic function assessment were performed at baseline and 3 months after LAAPC. An average of 3 consecutives measurements were performed for TEE parameters in all patients. Results Sixty-three patients (mean age 73±9 years) were included. 38% (n=24) in sinus rythm (SR) at baseline and 55% (n=35) in permanent AF. Patients in SR at baseline and permanent AF at 3 months were excluded (n=4,7%).The mean CHA2DS2-VASc score was 4,3±1,3. There was non significant difference in the functionnal status and BNP level (155,6±107 vs ±150,7pg/mL; p=0,85) between baseline and 3 months follow-up. Left atrial volume excluding the LAA (145 ±55cm 3 baseline vs 144±50cm 3 at 3 months; p=0,30) showed no significant change after 3 months in overall population, neither in the SR (99,7±19,1 vs 103,8±21cm 3 ; p=0,32) or the permanent AF groups (173,2±54 vs 171,7±48,6cm 3 ; p=0,59). MV peak E-wave (84,2±22,7 vs 86,7±26cm/s; p=0,62) and A-wave velocities (65,4±14,4; 68,5±22,2cm/s; p=0,66) dit not differ between baseline and follow-up but E/E’ ratio was increased in the overall population after LAAPC (7,9±2,1 vs 9,1±3,6cm/s; p=0,038) and there was trend to higher E/E’ ratio in the SR group (7,7±1,6 vs 9±3,3cm/s, p=0,46). Conclusions There’s no evidence for early LA remodeling after LAAPC, but diastolic function might be negatively influenced by LAAPC suggesting the potential role of LAA in atrial function. Further studies are warranted to confirm the prelimary results. [ABSTRACT FROM AUTHOR]