Mid-infrared size survey of Young Stellar Objects: Description of Keck segment-tilting experiment and basic results

The mid-infrared properties of pre-planetary disks are sensitive to the temperature and flaring profiles of disks for the regions where planet formation is expected to occur. In order to constrain theories of planet formation, we have carried out a mid-infrared (wavelength 10.7 microns) size survey of young stellar objects using the segmented Keck telescope in a novel configuration. We introduced a customized pattern of tilts to individual mirror segments to allow efficient sparse-aperture interferometry, allowing full aperture synthesis imaging with higher calibration precision than traditional imaging. In contrast to previous surveys on smaller telescopes and with poorer calibration precision, we find most objects in our sample are partially resolved. Here we present the main observational results of our survey of 5 embedded massive protostars, 25 Herbig Ae/Be stars, 3 T Tauri stars, 1 FU Ori system, and 5 emission-line objects of uncertain classification. The observed mid-infrared sizes do not obey the size-luminosity relation found at near-infrared wavelengths and a companion paper will provide further modelling analysis of this sample. In addition, we report imaging results for a few of the most resolved objects, including complex emission around embedded massive protostars, the photoevaporating circumbinary disk around MWC 361A, and the subarcsecond binaries T Tau, FU Ori and MWC 1080.Comment: Accepted by Astrophysical Journal. 38 pages. 9 figure

Imaging starspot evolution on Kepler target KIC 5110407 using light curve inversion

The Kepler target KIC 5110407, a K-type star, shows strong quasi-periodic light curve fluctuations likely arising from the formation and decay of spots on the stellar surface rotating with a period of 3.4693 days. Using an established light-curve inversion algorithm, we study the evolution of the surface features based on Kepler space telescope light curves over a period of two years (with a gap of .25 years). At virtually all epochs, we detect at least one large spot group on the surface causing a 1-10% flux modulation in the Kepler passband. By identifying and tracking spot groups over a range of inferred latitudes, we measured the surface differential rotation to be much smaller than that found for the Sun. We also searched for a correlation between the seventeen stellar flares that occurred during our observations and the orientation of the dominant surface spot at the time of each flare. No statistically-significant correlation was found except perhaps for the very brightest flares, suggesting most flares are associated with regions devoid of spots or spots too small to be clearly discerned using our reconstruction technique. While we may see hints of long-term changes in the spot characteristics and flare statistics within our current dataset, a longer baseline of observation will be needed to detect the existence of a magnetic cycle in KIC 5110407.Comment: 32 pages, 15 figures, accepted to Ap

Dose–response between frequency of interruption of sedentary time and fasting glucose, the dawn phenomenon and night-time glucose in Type 2 diabetes

Aim: To explore the dose-response between frequency of interruption of sedentary time and basal glucose (fasting glucose, the dawn phenomenon and night-time glucose) in Type 2 diabetes. Methods: In a randomized three-treatment, two-period balanced incomplete block trial, 12 people with Type 2 diabetes (age, 60.0 +/- 3.2 years; BMI, 30.2 +/- 1.4 kg/m(2)) completed two of three conditions: sitting for 7 h interrupted every 60 min (Condition 1), 30 min (Condition 2), and 15 min (Condition 3) by 3-min light-intensity walking breaks. The activPAL3 and FreeStyle Libre were used to assess physical activity/sedentary behaviour and continuous glucose profile. Standardized meals were provided, and changes in basal glucose of the nights and early mornings before and after treatment conditions were calculated (mean +/- SE). Results: After treatment conditions, fasting glucose and duration of the dawn phenomenon were lower for Condition 3 (-1.0 +/- 0.2 mmol/l, P < 0.02; -3.1 +/- 1.3 h, P = 0.004) compared with Condition 1 (-0.1 +/- 0.2 mmol/l; 1.9 +/- 1.2 h). The magnitude of the dawn phenomenon was reduced in Condition 3 (-0.6 +/- 0.4 mmol/l, P = 0.041) compared with Condition 2 (0.6 +/- 0.3 mmol/l). Night-time glycaemic variability (coefficient of variation) was reduced in Condition 3 (-9.7 +/- 3.9%) relative to Condition 2 (6.1 +/- 4.8%, P < 0.03) and Condition 1 (2.5 +/- 1.8%, P = 0.02). There was no change in night-time mean glucose. Conclusions: Frequent interruptions of prolonged sitting with 3 min of light-intensity walking breaks every 15 min improves fasting glucose, the dawn phenomenon and night-time glycaemic variability, and this might be a simple therapeutic intervention to improve glucose control. Clinicaltrials.gov Identifier: NCT0273899

Modélisation des sources d'émission acoustique : aide à l'identification de paramètres pertinents pour décrire l'endommagement des matériaux

L’Emission Acoustique (EA) est une technique de contrôle non-destructif capable de détecter les différents mécanismes d’endommagement se produisant lors de sollicitations mécaniques. Dans les matériaux composites, un des enjeux actuel est de relier chaque signal enregistré au mécanisme source (rupture de fibre, fissuration matricielle, décohésion fibre/matrice, etc.). Cependant, le signal source subit lors de sa propagation jusqu’au capteur de nombreuses transformations altérant sa forme et par conséquent les descripteurs extraits de ce signal (amplitude, énergie, etc.). Dans le contexte de la classification des phénomènes sources, la modélisation de ces transformations s’avère donc indispensable. Une étude par éléments finis a été réalisée à l’aide du logiciel ABAQUS© en simulant une éprouvette de traction de type haltère (dimensions : 200x24x3,7 mm3). Pour l’instant, l’étude a été réalisée sans prendre en compte une éventuelle évolution des propriétés élasto-mécaniques du milieu de propagation avec l’endommagement. L’objectif principal de cette étude est de quantifier l’influence de la propagation sur le signal enregistré. Des sources de nature différente en termes de temps de montée, de fréquence et d’énergie ont été générées. Le déplacement à la surface matériau a été calculé à différentes distances de la source. Les descripteurs les moins affectés sont les descripteurs fréquentiels (fréquence de pic et barycentre fréquentiel) qui rendent une bonne image de la source et sont peu affectés par la propagation. Par contre, nous avons pu montrer que l’énergie du signal, dont la valeur est très influencée par la géométrie de l’éprouvette, est très affectée par les réflexions. En outre, l’énergie ne décroissant pas de manière exponentielle avec la distance de propagation pour cette géométrie, il n’est pas possible d’établir une relation simple entre l’énergie du signal d’EA et l’énergie de la source. Enfin, l’étude de l’impact d’un endommagement progressif de l’éprouvette sur le signal d’EA est en cours d’analyse

Dagens høye gjeldsnivå: en trussel for boligmarkedet? : en empirisk studie av boligprisenes rentefølsomhet og i hvilken grad denne kan forsterkes av sårbarheten til husholdningene

Norske husholdninger sin gjeld er i dag på rekordhøye nivåer. Det lave rentenivået fører derimot til at gjelden ikke oppleves som særlig belastende for den private økonomien. Motivasjonen bak denne utredningen er å undersøke hvor sårbare norske husholdninger er ved økte utlånsrenter og om denne sårbarheten kan påvirke boligmarkedet. I første del av analysen finner vi klare holdepunkter for at boligprisene er betydelig følsomme for økninger i utlånsrentene og at denne følsomheten har blitt sterkere de siste ti årene. Både kortsiktige og langsiktige fluktuasjoner i boligprisene kan forklares av renteendringer. Bankenes utlånsrenter påvirker boligprisene ved at de reelle bokostnadene øker og lønnsomheten av å investere i bolig reduseres. Dette fører til at både etterspørselen og tilbudet av boliger reduseres. Samtidig spiller rentene en rolle for husholdningenes forventninger. I andre del av analysen finner vi at selv ved store økninger i utlånsrentene er norske husholdninger i stand til å betjene gjelden sin. Dette gjelder til en viss grad også husholdningene med de høyeste gjeldsnivåene. Disse funnene må ses i lys av den høye private forbruksveksten som har funnet sted i Norge. Ved økte renteutgifter har husholdningene mulighet til å kutte i forbruket for å kunne betjene boliglånene sine. Sårbarheten oppfattes derfor ikke som en direkte trussel for boligmarkedet, men kan trolig slå ut i redusert forbruk og gjennom dette påvirke boligprisene. Erfaringene fra bankkrisen på slutten av 1980-tallet, hvor bedriftenes inntjeningsevne ble betydelig svekket, tilsier at gjeldsnivåene blant husholdningene bør vekke bekymring

Firmware implementation of a recurrent neural network for the computation of the energy deposited in the liquid argon calorimeter of the ATLAS experiment

The ATLAS experiment measures the properties of particles that are products of proton-proton collisions at the LHC. The ATLAS detector will undergo a major upgrade before the high luminosity phase of the LHC. The ATLAS liquid argon calorimeter measures the energy of particles interacting electromagnetically in the detector. The readout electronics of this calorimeter will be replaced during the aforementioned ATLAS upgrade. The new electronic boards will be based on state-of-the-art field-programmable gate arrays (FPGA) from Intel allowing the implementation of neural networks embedded in firmware. Neural networks have been shown to outperform the current optimal filtering algorithms used to compute the energy deposited in the calorimeter. This article presents the implementation of a recurrent neural network (RNN) allowing the reconstruction of the energy deposited in the calorimeter on Stratix 10 FPGAs. The implementation in high level synthesis (HLS) language allowed fast prototyping but fell short of meeting the stringent requirements in terms of resource usage and latency. Further optimisations in Very High-Speed Integrated Circuit Hardware Description Language (VHDL) allowed fulfilment of the requirements of processing 384 channels per FPGA with a latency smaller than 125 ns.Comment: 13 pages, 8 figure

Transferring climate change knowledge

Accurate climate projections are required for climate adaptation and mitigation. Earth system model simulations, used to project climate change, inherently make approximations in their representation of small-scale physical processes, such as clouds, that are at the root of the uncertainties in global mean temperature's response to increased greenhouse gas concentrations. Several approaches have been developed to use historical observations to constrain future projections and reduce uncertainties in climate projections and climate feedbacks. Yet those methods cannot capture the non-linear complexity inherent in the climate system. Using a Transfer Learning approach, we show that Machine Learning, in particular Deep Neural Networks, can be used to optimally leverage and merge the knowledge gained from Earth system model simulations and historical observations to more accurately project global surface temperature fields in the 21st century. For the Shared Socioeconomic Pathways (SSPs) 2-4.5, 3-7.0 and 5-8.5, we refine regional estimates and the global projection of the average global temperature in 2081-2098 (with respect to the period 1850-1900) to 2.73{\deg}C (2.44-3.11{\deg}C), 3.92{\deg}C (3.5-4.47{\deg}C) and 4.53{\deg}C (3.69-5.5{\deg}C), respectively, compared to the unconstrained 2.7{\deg}C (1.65-3.8{\deg}C), 3.71{\deg}C (2.56-4.97{\deg}C) and 4.47{\deg}C (2.95-6.02{\deg}C). Our findings show that the 1.5{\deg}C threshold of the Paris' agreement will be crossed in 2031 (2028-2034) for SSP2-4.5, in 2029 (2027-2031) for SSP3-7.0 and in 2028 (2025-2031) for SSP5-8.5. Similarly, the 2{\deg}C threshold will be exceeded in 2051 (2045-2059), 2044 (2040-2047) and 2042 (2038-2047) respectively. Our new method provides more accurate climate projections urgently required for climate adaptation

Recent developments in optical interferometry data standards

A working group on interferometry data standards has been established within IAU Commission 54 (Optical/ Infrared Interferometry). The working group includes members representing the major optical interferometry projects worldwide, and aims to enhance existing standards and develop new ones to satisfy the broad interests of the optical interferometry community. We present the initial work of the group to enhance the OIFITS data exchange standard, and outline the software packages and libraries now available which implement the standard