Integrability and Wilson loops: the wavy line contour

The Wilson loop with a wavy line contour is studied using integrable methods. The auxiliary problem is solved and the Lax operator is built to first order in perturbation theory, considering a small perturbation from the straight line. Finally the spectral curve of the solution is considered.Comment: 10 page

More on integrable structures of superstrings in AdS(4) x CP(3) and AdS(2) x S(2) x T(6) superbackgrounds

In this paper we continue the study, initiated in arXiv:1009.3498 and arXiv:1104.1793, of the classical integrability of Green-Schwarz superstrings in AdS(4) x CP(3) and AdS(2) x S(2) x T(6) superbackgrounds whose spectrum contains non-supercoset worldsheet degrees of freedom corresponding to broken supersymmetries in the bulk. We derive an explicit expression, to all orders in the coset fermions and to second order in the non-coset fermions, which extends the supercoset Lax connection in these backgrounds with terms depending on the non-coset fermions. An important property of the obtained form of the Lax connection is that it is invariant under Z_4-transformations of the superisometry generators and the spectral parameter. This demonstrates that the contribution of the non-coset fermions does not spoil the Z_4-symmetry of the super-coset Lax connection which is of crucial importance for the application of Bethe-ansatz techniques. The expressions describing the AdS(4) x CP(3) and AdS(2) x S(2) x T(6) superstring sigma--models and their Lax connections have a very similar form. This is because their amount of target-space supersymmetries complement each other to 32=24+8, the maximal number of 10d type II supersymmetries. As a byproduct, this similarity has allowed us to obtain the form of the geometry of the complete type IIA AdS(2) x S(2) x T(6) superspace to all orders in the coset fermions and to the second order in the non-coset ones.Comment: 28 pages; v2: References adde

HEMP: High-order entropy minimization for neural network compression

We formulate the entropy of a quantized artificial neural network as a differentiable function that can be plugged as a regularization term into the cost function minimized by gradient descent. Our formulation scales efficiently beyond the first order and is agnostic of the quantization scheme. The network can then be trained to minimize the entropy of the quantized parameters, so that they can be optimally compressed via entropy coding. We experiment with our entropy formulation at quantizing and compressing well-known network architectures over multiple datasets. Our approach compares favorably over similar methods, enjoying the benefits of higher order entropy estimate, showing flexibility towards non-uniform quantization (we use Lloyd-max quantization), scalability towards any entropy order to be minimized and efficiency in terms of compression. We show that HEMP is able to work in synergy with other approaches aiming at pruning or quantizing the model itself, delivering significant benefits in terms of storage size compressibility without harming the model's performance

Application of an innovative model for the risk management of covid-19 in a multinational manufacturing company

The COVID-19 incidence in 61 manufacturing plants in Europe (EU), North America (NA) and Latin-America (LATAM) was compared with the incidence observed in the countries where the plants are located in order to evaluate the application of an innovative model for COVID-19 risk management. Firstly, a network of local and global teams was created, including an external university occupational physician team for scientific support. In July 2020, global prevention guidelines for the homogenous management of the pandemic were applied, replacing different site or regional procedures. A tool for COVID-19 monitoring was implemented to investigate the relationship between the incidence rates inside and outside the plants. In the period of May–November 2020, 565 confirmed cases (EU 330, NA 141, LATAM 94) were observed among 20,646 workers with different jobs and tasks, and in the last two months 85% EU and 70% NA cases were recorded. Only in 10% of cases was a possible internal origin of the contagion not excluded. In the EU and NA, unlike LATAM, the COVID-19 incidence rates inside the sites punctually followed the rising trend outside. In conclusion, the model, combining a global approach with the local application of the measures, maintains the sustainability in the manufacturing industry

Stratosphere-troposphere coupling at inter-decadal time scales: Implications for the North Atlantic Ocean

Evidence of stratosphere-troposphere coupling at inter-decadal time scales is searched for in a 260-year simulation performed with a climate model including a state-of-the-art stratosphere. The boundary conditions of the simulation are specified according to preindustrial conditions and are kept constant from year to year. It is shown that long lasting (∼20 years) positive and negative anomalies of the northern winter stratospheric polar vortex exist in the simulation. Given that there are no externally imposed low frequency time variations, these persistent variations are due to internal dynamical processes of the modeled coupled atmosphere ocean system. By composite analysis, it is shown that the long lasting stratospheric vortex anomalies are connected through the troposphere to mean sea level pressure, surface temperature and sea ice cover anomalies. These connections are reminiscent of intra-seasonal stratosphere-troposphere coupling. Over the ocean, the surface temperature and sea ice cover anomalies are indicative of the delayed Atlantic meridional overturning circulation response to atmospheric forcing. The latter is indeed found to be anomalously strong/weak during the long lasting positive/negative stratospheric vortex anomalies, providing evidence for a potential role of the stratosphere in decadal prediction. Copyright 2012 by the American Geophysical Union

Morphology of the tropopause layer and lower stratosphere above a tropical cyclone : a case study on cyclone Davina (1999)

During the APE-THESEO mission in the Indian Ocean the Myasishchev Design Bureau stratospheric research aircraft M55 Geophysica performed a flight over and within the inner core region of tropical cyclone Davina. Measurements of total water, water vapour, temperature, aerosol backscattering, ozone and tracers were made and are discussed here in comparison with the averages of those quantities acquired during the campaign time frame. Temperature anomalies in the tropical tropopause layer (TTL), warmer than average in the lower part and colder than average in the upper TTL were observed. Ozone was strongly reduced compared to its average value, and thick cirrus decks were present up to the cold point, sometimes topped by a layer of very dry air. Evidence for meridional transport of trace gases in the stratosphere above the cyclone was observed and perturbed water distribution in the TTL was documented. The paper discuss possible processes of dehydration induced by the cirrus forming above the cyclone, and change in the chemical tracer and water distribution in the lower stratosphere 400–430 K due to meridional transport from the mid-latitudes and link with Davina. Moreover it compares the data prior and after the cyclone passage to discuss its actual impact on the atmospheric chemistry and thermodynamics

Impact of an improved radiation scheme in the MAECHAM5 General Circulation Model

In order to improve the representation of the shortwave radiative transfer in the MAECHAM5 general circulation model, the spectral resolution of the shortwave radiation parameterization used in the model has been increased and extended in the UV-B and UV-C bands. The upgraded shortwave parameterization is first validated offline with a 4 stream discrete-ordinate line-by-line model. Thereafter, two 20-years simulations with the MAECHAM5 middle atmosphere general circulation model are performed to evaluate the temperature changes and the dynamical feedbacks arising from the newly introduced parameterization. The offline clear-sky comparison of the standard and upgraded parameterizations with the discrete ordinate model shows considerable improvement for the upgraded parameterization in terms of shortwave fluxes and heating rates. In the simulation with the upgraded ratiation parameterization, we report a significant warming of almost the entire atmosphere, largest at 1 hPa at the stratopause, and stronger zonal mean zonal winds in the middle atmosphere. The warming at the summer stratopause alleviates the cold bias present in the model when the standard radiation scheme is used. The stronger zonal mean zonal winds induce a dynamical feedback that results in a dynamical warming (cooling) of the polar winter (summer) mesosphere, caused by an increased downward (upward)circulation in the winter (summer) hemisphere. In the troposphere, the changes in the spectral resolution and the associated changes in the cloud optical parameters introduce a relatively small warming and, consistenly, a moisteneing. The warming occurs mostly in the upper troposphere and can contribute to a possible improvement of the model temperature climatology

Impact of an improved shortwave radiation scheme in the MAECHAM5 General Circulation Model

International audienceIn order to improve the representation of ozone absorption in the stratosphere of the MAECHAM5 general circulation model, the spectral resolution of the shortwave radiation parameterization used in the model has been increased from 4 to 6 bands. Two 20-years simulations with the general circulation model have been performed, one with the standard and the other with the newly introduced parameterization respectively, to evaluate the temperature and dynamical changes arising from the two different representations of the shortwave radiative transfer. In the simulation with the increased spectral resolution in the radiation parameterization, a significant warming of almost the entire model domain is reported. At the summer stratopause the temperature increase is about 6 K and alleviates the cold bias present in the model when the standard radiation scheme is used. These general circulation model results are consistent both with previous validation of the radiation scheme and with the offline clear-sky comparison performed in the current work with a discrete ordinate 4 stream scattering line by line radiative transfer model. The offline validation shows a substantial reduction of the daily averaged shortwave heating rate bias (1?2 K/day cooling) that occurs for the standard radiation parameterization in the upper stratosphere, present under a range of atmospheric conditions. Therefore, the 6 band shortwave radiation parameterization is considered to be better suited for the representation of the ozone absorption in the stratosphere than the 4 band parameterization. Concerning the dynamical response in the general circulation model, it is found that the reported warming at the summer stratopause induces stronger zonal mean zonal winds in the middle atmosphere. These stronger zonal mean zonal winds thereafter appear to produce a dynamical feedback that results in a dynamical warming (cooling) of the polar winter (summer) mesosphere, caused by an increased downward (upward) circulation in the winter (summer) hemisphere. In addition, the comparison of the two simulations performed with the general circulation model shows that the increase in the spectral resolution of the shortwave radiation and the associated changes in the cloud optical properties result in a warming (0.5?1 K) and moistening (3%?12%) of the upper tropical troposphere. By comparing these modeled differences with previous works, it appears that the reported changes in the solar radiation scheme contribute to improve the model mean temperature also in the troposphere