Application of neural networks to synchro-Compton blazar emission models

Jets from supermassive black holes in the centers of active galaxies are the most powerful persistent sources of electromagnetic radiation in the Universe. To infer the physical conditions in the otherwise out-of-reach regions of extragalactic jets we usually rely on fitting of their spectral energy distribution (SED). The calculation of radiative models for the jet non-thermal emission usually relies on numerical solvers of coupled partial differential equations. In this work machine learning is used to tackle the problem of high computational complexity in order to significantly reduce the SED model evaluation time, which is needed for SED fitting with Bayesian inference methods. We compute SEDs based on the synchrotron self-Compton model for blazar emission using the radiation code ATHE${\nu}$A, and use them to train Neural Networks exploring whether these can replace the original computational expensive code. We find that a Neural Network with Gated Recurrent Unit neurons can effectively replace the ATHE${\nu}$A leptonic code for this application, while it can be efficiently coupled with MCMC and nested sampling algorithms for fitting purposes. We demonstrate this through an application to simulated data sets and with an application to observational data. We offer this tool in the community through a public repository. We present a proof-of-concept application of neural networks to blazar science. This is the first step in a list of future applications involving hadronic processes and even larger parameter spaces.Comment: 12 pages, submitted, comments are welcome, code will be soon available at https://github.com/tzavellas/blazar_m

The interplay between double exchange, super-exchange, and Lifshitz localization in doped manganites

Considering the disorder caused in manganites by the substitution of Mn by Fe or Ga, we accomplish a systematic study of doped manganites begun in previous papers. To this end, a disordered model is formulated and solved using the Variational Mean Field technique. The subtle interplay between double exchange, super-exchange, and disorder causes similar effects on the dependence of T_C on the percentage of Mn substitution in the cases considered. Yet, in La$_{2/3}$Ca$_{1/3}$Mn$_{1-y}$Ga$_y$O$_3$ our results suggest a quantum critical point (QCP) for $y\approx 0.1-0.2$, associated to the localization of the electronic states of the conduction band. In the case of La$_x$Ca$_x$Mn$_{1-y}$Fe$_y$O$_3$ (with $x=1/3,3/8$) no such QCP is expected.Comment: 6 pages + 3 postscript figures. Largely extended discussio

Mirtazapine and venlafaxine in the management of collateral psychopathology during alcohol detoxification

Symptoms of anxiety and depression are common in a large proportion of alcohol-abusing/dependent individuals during alcohol detoxification. The aim of this study was to examine the impact of a combined psychotherapeutic-psychopharmacological (either with mirtazapine or venlafaxine) treatment of these symptoms during the earl), withdrawal phase of alcohol compared to a group treated only with psychotherapy. A total of 60 alcohol-dependent/abusing subjects randomly assigned to three groups (psychotherapy, psychotherapy plus mirtazapine, psychotherapy plus venlafaxine) were studied. Assessment of psychopathology and global functioning throughout a 4-5-week detoxification period was done by the Hamilton Anxiety Rating Scale (HARS), the Hamilton Depression Rating Scale (HDRS). and the Global Assessment Scale (GAS). At baseline, high scores of anxiety and depression were recorded (HARS: controls: 33.1 +/- 7.8. mirtazapine: 33.2 +/- 12.6, venlafaxine: 36.6 +/- 5.4; HDRS: controls: 39.5 +/- 7.4, mirtazapine: 37.9 +/- 7.8. venlafaxine: 41.9 +/- 4.5). A marked improvement patients on mirtazapine improved significantly more (p<0.000) was evidenced in all groups by the end of the detoxification period. However patients compared to the other two groups (HARS: controls: 9.6 +/- 7.6, mirtazapine: 4.3 +/- 4.4*. venlafaxine: 7.2 +/- 4.1. *p=0.011; HDRS: controls: 8.6 +/- 7.9, mirtazapine: 3.8 +/- 3.2*, venlafaxine: 8.2 +/- 3.5, *p=0.017; GAS: controls: 79.5 +/- 9.4. mirtazapine: 87.5 +/- 5.5**. venlafaxine: 83.0 +/- 8.0, **p=0.006). It is concluded that addition of mirtazapine, but not venlafaxine. to a standard psychotherapy-oriented alcohol detoxification treatment may facilitate the detoxification process by minimizing psychological discomfort. Consequently. it may prove to be a facilitator for the long-term abstinence from alcohol. (C) 2004 Elsevier Inc. All rights reserved

A game theory approach for coordinating multiple virtual synchronous generators

In the last two decades, there has been an increasing investment on renewable technologies. To this extent, massive number of small wind turbines and Photovoltaic Arrays are being installed and integrated in electrical power systems. This leads to a trend to convert current centralized power production by rotating machines to decentralized power electronic interfaced production. A potential impact of this tendency is increased instability due to the decrement of available rotating inertia. The introduction of virtual inertia by combining the storage and inverter control technologies is emerging to compensate lacking grid inertia thus keep system stable. Single unit of this so-called Virtual Synchronous Generator (VSG) has been investigated intensively, yet there is little research on multiple unit operation. This paper proposes a cooperative game which can be used to model cooperation between several VSG units. The game is solved using the Nucleolus theory and it is applied on a simulated microgrid with up to three VSG units integrated. The dynamic performance of the system will be compared in different scenarios (with different number of VSG units)and the effectiveness of the approach will be demonstrated

Configurational preferences of two 1,2-diamine adducts of bis(1-(2-thienyl)-4,4,4-trifluoro-1,3-butanedionato)cobalt(II)

The preparation, the IR and ligand field spectra and the structures of the mixed-ligand addition compounds [(N,N-dimethyl-1,2-diaminoethane)bis(1-(2-thienyl)-4,4,4-trifluoro-1,3-butanedionato)cobalt(II)], [Co(thtf)2me2en], and [(N,N,N′,N′-tetramethyl-1,2-diaminoethane)bis(1-(2-thienyl)-4,4,4-trifluoro-1,3-butanedionato)cobalt(II)], [Co(thtf)2me4en], are reported. The structures were determined by single crystal X-ray diffraction analysis (monoclinic, space group P21/c, Z=4 with a=10.708(6), b=19.531(6), c=13.352(6) Å, β=111.64(10)°, R1=0.0642 and wR2=0.1719 for [Co(thtf)2(me2en)] and a=12.033(6), b=15.565(6), c=15.339(6) Å, β=92.57(6)°, R1=0.0612 and wR2=0.1504 for [Co(thtf)2me4en]). The structures are distorted octahedral and the shortest cobalt–cobalt separation distances are 5.388(2) Å in [Co(thtf)2me2en] and 8.675(3) Å in [Co(thtf)2me4en]. In both compounds the diamine molecules attain the gauche conformation. The U(Z,Z) conformation of the β-dione leads to a semi-chair conformation of the β-dionato chelate rings. The relative orientation of the groups attached to the β-dionato moiety depends on the extent of stereoelectronic effects the N-substitution of the diamine entails. In [Co(thtf)2me2en] the intraligand distance separating the trifluoromethyl carbon atoms is 5.281(18) Å while in [Co(thtf)2me2en] it increases to 8.338(9) Å. The cobalt–cobalt separation distance, the orientation of the chelate rings and the extent of N-substitution seem to affect hydrogen bonding. While in [Co(thtf)2me2en] inter- and intraligand hydrogen bonding is implicated, it is totally absent in [Co(thtf)2me4en]

Influence of hydrogen bonding in the structure of mixed-ligand copper(II) chelates. Spectra and structure of [aquo((2,2'-dipyridylamine)-(3-chloro-2,4-pentanedionato)copper(II)] nitrate

The IR, the ligand field spectra and the crystal structure of the mixed-ligand compound [(aquo)2,2P1 , a = 8.718(5), b = 9.407(5), c = 13.484 (7) Å, = 94.17(4)°, = 105.12(5)°, = 119.75(5)°, Z = 2, R = 0.0332, R W = 0.0869)

Development and validation of the Schedule for the Assessment of Insight in Alcohol Dependence (SAI-AD): Dimensions and correlates of insight in alcohol use disorder

Introduction: The objectives of this study were to develop a multidimensional, clinician-rated scale that assess impaired insight into illness in patients with alcohol use disorder (AUD) and to examine its reliability, validity and internal structure. Moreover, we investigated the relationships of overall insight and its dimensions with demographic and clinical characteristics in AUD. Methods: We developed the Schedule for the Assessment of Insight in Alcohol Dependence (SAI-AD), based on scales that has already been used in psychosis and other mental disorders. Sixty-four patients with AUD were assessed with SAI-AD. Hierarchical cluster analysis and multidimensional scaling were used to identify insight components and assess their inter-relationships. Results: The SAI-AD demonstrated good convergent validity (r = −0.73, p < 0.001) and internal consistency (Cronbach's alpha = 0.72). Inter-rater and test-retest reliabilities were high (intra-class correlations 0.90 and 0.88, respectively). Three subscales of SAI-AD were identified which measure major insight components: awareness of illness, recognition of symptoms and need for treatment, and treatment engagement. Higher levels of depression, anxiety and AUD symptom severity were associated with overall insight impairment but not with recognition of symptoms and need for treatment, or with treatment engagement. Illness duration was specifically and positively associated with the treatment engagement component of insight. Conclusions: Insight is a multidimensional construct in AUD and its major components appear to be associated with different clinical aspects of the disorder. The SAI-AD is a valid and reliable tool for the assessment of insight in AUD patients