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Context. Young solar analogs reaching the main sequence experience very strong magnetic activity, generating angular momentum losses through wind and mass ejections. Aims. We investigate signatures of magnetic fields and activity at the surface and in the prominence system of the ultra-rapid rotator V530 Per, a G-type solar-like member of the young open cluster α Persei. This object has a rotation period that is shorter than all stars with available magnetic maps. Methods. With a time-series of spectropolarimetric observations gathered with ESPaDOnS over two nights on the Canada-France-Hawaii Telescope, we reconstructed the surface brightness and large-scale magnetic field of V530 Per using the Zeeman-Doppler imaging method, assuming an oblate stellar surface. We also estimated the short term evolution of the brightness distribution through latitudinal differential rotation. Using the same data set, we finally mapped the spatial distribution of prominences through tomography of the Hα emission. Results. The brightness map is dominated by a large, dark spot near the pole, accompanied by a complex distribution of bright and dark features at lower latitudes. Taking the brightness map into account, the magnetic field map is reconstructed as well. Most of the large-scale magnetic field energy is stored in the toroidal field component. The main radial field structure is a positive region of about 500 G, at the location of the dark polar spot. The brightness map of V530 Per is sheared by solar-like differential rotation, with roughly a solar value for the difference in rotation rate between the pole and equator. It is important to note that Hα is observed in emission and it is mostly modulated by the stellar rotation period over one night. The prominence system is organized in a ring at the approximate location of the corotation radius, and displays significant evolution between the two observing nights. Conclusions. V530 Per is the first example of a solar-type star to have its surface magnetic field and prominences mapped together, which will bring important observational constraints to better understand the role of slingshot prominences in the angular momentum evolution of the most active stars. [ABSTRACT FROM AUTHOR]

We report on low temperature conductance measurements of gold nanogaps fabricated by controlled electromigration. Fluctuations of the conductance due to quantum interferences and depending both on bias voltage and magnetic field are observed. By analyzing the voltage and magnetoconductance correlation functions, we determine the type of electron trajectories generating the observed quantum interferences and the effective characteristic time of phase coherence in our device. [ABSTRACT FROM AUTHOR]

Wet thermal oxidation of AlAsSb was investigated. The oxidation kinetics was studied as a function of temperature and oxidation duration. An expression to allow accurate determination of the oxide depth for any temperature and time was established. Secondary ion mass spectrometry profiles and x-ray diffraction were used to demonstrate that an interfacial layer, composed of pure Sb and As and textured on InP, is formed during the oxidation process. [ABSTRACT FROM AUTHOR]

Magnetic fields are essential ingredients of many physical processes in the interiors and envelopes of cool stars. Yet their direct detection and characterization is notoriously difficult, requiring high-quality observations and advanced analysis techniques. Significant progress has been recently achieved by several types of direct magnetic field studies on the surfaces of cool, active stars. In particular, complementary techniques of field topology mapping with polarization data and total magnetic flux measurements from intensity spectra have been systematically applied to different classes of active stars, leading to interesting and occasionally controversial results. In this paper, we summarize the current status of direct magnetic field studies of cool stars and investigations of surface inhomogeneities caused by the field, based on the material presented at the Cool Stars 19 splinter session. [ABSTRACT FROM AUTHOR]

The surface rotation rates of young solar-type stars vary rapidly with age from the end of the pre-main sequence through the early main sequence. Important changes in the dynamos operating in these stars may result from this evolution, which should be observable in their surface magnetic fields. Here we present a study aimed at observing the evolution of these magnetic fields through this critical time period. We observed stars in open clusters and stellar associations of known ages, and used Zeeman Doppler imaging to characterize their complex magnetic large-scale fields. Presented here are results for 15 stars, from five associations, with ages from 20 to 250 Myr, masses from 0.7 to 1.2 M☉, and rotation periods from 0.4 to 6 d. We find complex large-scale magnetic field geometries, with global average strengths from 14 to 140 G. There is a clear trend towards decreasing average large-scale magnetic field strength with age, and a tight correlation between magnetic field strength and Rossby number. Comparing the magnetic properties of our zero-age main-sequence sample to those of both younger and older stars, it appears that the magnetic evolution of solar-type stars during the pre-main sequence is primarily driven by structural changes, while it closely follows the stars' rotational evolution on the main sequence. [ABSTRACT FROM AUTHOR]

Aims.We develop a fully Bayesian least squares deconvolution (LSD) that can be applied to the reliable detection of magnetic signals in noise-limited stellar spectropolarimetric observations using multiline techniques. Methods. We consider LSD under the Bayesian framework and we introduce a flexible Gaussian process (GP) prior for the LSD profile. This prior allows the result to automatically adapt to the presence of signal. We exploit several linear algebra identities to accelerate the calculations. The final algorithm can deal with thousands of spectral lines in a few seconds. Results. We demonstrate the reliability of the method with synthetic experiments and we apply it to real spectropolarimetric observations of magnetic stars. We are able to recover the magnetic signals using a small number of spectral lines, together with the uncertainty at each velocity bin. This allows the user to consider if the detected signal is reliable. The code to compute the Bayesian LSD profile is freely available. [ABSTRACT FROM AUTHOR]

Résumé Objectifs Cet article propose une synthèse de la littérature sur une partie des mécanismes biologiques impliqués dans la maladie d’Alzheimer et sur leur évolution dans le cadre d’interventions non pharmacologiques. Actualités L’activité physique régulière aérobie et l’environnement enrichi sont deux méthodes issues respectivement de l’hypothèse métabolique et de l’hypothèse de l’enrichissement cognitif. Leurs effets sur l’aptitude aérobie, la fonction cardiorespiratoire, la structure cérébrale et la cognition sont clairement établis dans le vieillissement chez l’animal et chez l’homme. Dans la maladie d’Alzheimer, ces méthodes pourraient interrompre l’évolution physiopathologique mitochondriale, amyloïdogénique et des protéines tau. Perspectives et projets Chez les personnes âgées, l’utilisation des exergames (jeux vidéo à activité physique) se développe pour essayer de rendre les activités physiques plus attractives. Ces nouvelles technologies, à fort potentiel, permettraient de proposer simultanément de l’activité aérobie dans un environnement enrichi. Des recherches interventionnelles sur la faisabilité et les effets des exergames pour les patients Alzheimer doivent être explorées. Conclusion Nous proposons d’utiliser des serious (exer)games pour la prise en charge du patient Alzheimer. Ces serious games , développés spécifiquement pour le patient Alzheimer, auraient pour objectif d’intégrer l’activité aérobie d’intensité élevée et l’environnement enrichi pour une prise en charge accessible et ludique. Summary Aims This article summarizes the literature on some of the biological mechanisms involved in Alzheimer disease and their evolution in the context of non-pharmacological interventions. Actuality Regular aerobic physical activity and enriched environment are two methods derived from the metabolic hypothesis and the cognitive enrichment hypothesis respectively. Their effects on aerobic fitness, cardiorespiratory function, brain structure and cognition are clearly established in the aging process in humans and animals. In the field of Alzheimer's disease, these methods might halt mitochondrial, amyloidogenic and tau pathophysiological development. Perspectives In elderly patients, the use of exergames (active video games) develops in order to make physicals activities more attractive. These new technologies, with high potential, would propose simultaneously aerobic activity in an enriched environment. Intervention research on the feasibility and the effects of these exergames for Alzheimer patients may be a way forward. Conclusion We propose to use serious (exer)games to stimulate Alzheimer patients. These serious games, being specifically developed for Alzheimer patients, would be to integrate high intensity aerobic activity and enriched environment into a ludic and accessible therapy. [ABSTRACT FROM AUTHOR]

We present the results of a major high-resolution spectropolarimetric BCool project magnetic survey of 170 solar-type stars. Surface magnetic fields were detected on 67 stars, with 21 classified as mature solar-type stars, a result that increases by a factor of 4 the number of mature solar-type stars on which magnetic fields have been observed. In addition, a magnetic field was detected for 3 out of 18 of the subgiant stars surveyed. For the population of K-dwarfs, the mean value of |Bl| (|Bl|mean) was also found to be higher (5.7 G) than |Bl|mean measured for the G-dwarfs (3.2 G) and the F-dwarfs (3.3 G). For the sample as a whole, |Bl|mean increases with rotation rate and decreases with age, and the upper envelope for |Bl| correlates well with the observed chromospheric emission. Stars with a chromospheric S-index greater than about 0.2 show a high magnetic field detection rate and so offer optimal targets for future studies. This survey constitutes the most extensive spectropolarimetric survey of cool stars undertaken to date, and suggests that it is feasible to pursue magnetic mapping of a wide range of moderately active solar-type stars to improve our understanding of their surface fields and dynamos. [ABSTRACT FROM AUTHOR]

The young K-dwarf ϵ Eridani is an example of a young active planet hosting star that has shown over long-term monitoring of its chromospheric emission to exhibit cyclic magnetic activity. In this paper, we investigate how ϵ Eridani's large-scale magnetic field geometry evolves over the timescale of its S-index cycle using spectropolarimetric observations and the technique of Zeeman-Doppler imaging. Our observations comprise six epochs secured over a time period of nearly seven years, with each almost yearly observational epoch showing a dramatic change in the large-scale magnetic field topology, with no stable regions. The poloidal field varies from strongly dipolar to mono-polar and the toroidal field is non-existent to begin with and then emerges to dominate the magnetic field energy before disappearing and re-emerging again. A potential cycle is detected in the poloidal field, but further observations are needed to confirm this. [ABSTRACT FROM AUTHOR]

PolarBase is an evolving database that contains all stellar data collected with the ESPaDOnS and NARVAL high-resolution spectropolarimeters, in their reduced form, as soon as they become public. As of early 2014, observations of 2000 stellar objects throughout the Hertzsprung-Russell diagram are available. Intensity spectra are available for all targets, and the majority of the observations also include simultaneous spectra in circular or linear polarization, with the majority of the polarimetric measurements being performed only in circularly polarized light (Stokes V ). Observations are associated with a cross-correlation pseudoline profile in all available Stokes parameters, greatly increasing the detectability of weak polarized signatures. Stokes V signatures are detected for more than 300 stars of all masses and evolutionary stages, and linear polarization is detected in 35 targets. The detection rate in Stokes V is found to be anticorrelated with the stellar effective temperature. This unique set of Zeeman detections offers the first opportunity to run homogeneous magnetometry studies throughout the H-R diagram. [ABSTRACT FROM AUTHOR]

We investigate the Kondo effect in nanometer-sized carbon nanotube quantum dots fabricated by electromigration. Here, we report on a pronounced dip within the Kondo peak observed at zero magnetic field. The zero-bias conductance exhibits a nonmonotonic temperature dependence with two characteristic energy scales. This behavior is ascribed to a two-stage Kondo effect occurring in an even charge state of the quantum dot. We demonstrate the universal behavior of the out-of-equilibrium conductance in this regime, and we extract the parameters of the universal scaling function. [ABSTRACT FROM AUTHOR]

Aims. We study the behavior of the magnetic field and the line activity indicators of the single late-type giant β Ceti. Using spectropolarimetric data, we aim to reconstruct the magnetic field structure on the star's surface and to present the first magnetic maps for β Ceti. Methods. The data were obtained using two spectropolarimeters – Narval at the Bernard Lyot Télescope, Pic du Midi, France, and ESPaDOnS at CFHT, Hawaii. Thirty-eight circularly-polarized spectra have been collected in the period June 2010–January 2012. The least square deconvolution method was applied for extracting high signal-to-noise ratio line profiles, from which we measured the surface-averaged longitudinal magnetic field Bl. Chromospheric activity indicators CaII K, Hα, CaII IR (854.2 nm), and radial velocity were simultaneously measured, and their variability was analyzed along with the behavior of Bl. The Zeeman Doppler imaging (ZDI) inversion technique was employed for reconstructing the large-scale magnetic field and two magnetic maps of β Ceti are presented for two periods (June 2010–December 2010 and June 2011–January 2012). Results. The Bl stays with a same positive polarity for the whole observational period and shows significant variations in the interval 0.1–8.2 G. The behavior of the line activity indicators is in good agreement with the Bl variations. Searching for periodic signals in the Stokes V time series, we found a possible rotation period of 215 days. The two ZDI maps show a mainly axisymmetric and poloidal magnetic topology and a simple surface magnetic field configuration dominated by a dipole. Little evolution is observed between the two maps, in spite of a 1 yr interval between both subsets. We also use state-of-the-art stellar evolution models to constrain the evolutionary status of β Ceti. We derive a mass of 3.5 M⊚ and propose that this star is already in the central helium-burning phase. Conclusions. Considering all our results and the evolutionary status of the star, we suggest that dynamo action alone may not be efficient enough to account for the high magnetic activity of β Ceti. As an alternate option, we propose that it is a descendant of an Ap star presently undergoing central helium-burning and still exhibiting a remnant of the Ap star magnetic field. [ABSTRACT FROM AUTHOR]

Les infections virales respiratoires constituent une cause majeure de consultations aux urgences et d'hospitalisations, au sein de tous les groupes d'âges. Les rhinovirus, le virus respiratoire syncytial, le virus de la grippe et les coronavirus sont les mieux connus et considérés comme les plus prévalents. Les virus parainfluenza, des virus à ARN simple brin appartenant au genre Paramyxovirus sont moins bien connus et leur prévalence est possiblement sous-estimée du fait qu'on ne les recherche pas systématiquement. Ils causent habituellement des maladies bénignes de l'arbre respiratoire mais peuvent parfois être associés à des manifestations plus sévères comme des pneumonies, des exacerbations de BPCO ou d'asthme. Il existe 4 types de virus parainfluenza, nommés HPIV1 à 4. Très peu de données existent sur l'épidémiologie du HPIV4. L'objectif est de décrire rétrospectivement l'épidémiologie des infections à HPIV4, sur une période de 3 ans, soit de début 2017 à fin 2019. Les échantillons respiratoires inclus dans cette analyse rétrospective ont été reçus entre le 1er janvier 2017 et le 1er janvier 2020. La recherche de HPIV4 a été réalisée par PCR en temps réel avec les kits FTD Respiratory pathogens 21 (Fast Track Diagnosis, Luxembourg) ou Biofire Filmarray Respiratory panel 2 plus (Biomérieux, France). Un total de 16 357 correspondant à 11 976 patients a été testé entre le 1er janvier 2017 et le 31/12/2019. HPIV4 a été détecté dans 97 prélèvements respiratoires appartenant à 84 patients. Le sex-ratio était de 0,74 (36 hommes et 48 femmes). L'âge moyen des cas était de 28 ans (âge médian : 4 ans) ; à noter que 38,5 % des cas (32 patients) étaient âgés de 1 an ou moins. On comptait des 6 doubles infections avec HPIV2, 1 avec HPIV3, 1 triple infection avec HPIV2 + HPIV3, et 1 avec HPIV1 + HPIV2. Un décès a été notifié, il s'agissait d'une femme de 86 ans grabataire, initialement adressée pour chute avec traumatisme crânien, dans un contexte de décompensation cardiaque. Quatre jours après le début de son hospitalisation, la patiente a présenté une dégradation respiratoire avec acidose hypercapnique sur pneumopathie probable. Staphylococcus aureus avait été isolé d'une hémoculture et seul HPIV4 avait été retrouvé au niveau de ses prélèvements respiratoires. Un traitement par piperacilline tazobactam a été instauré. L'évolution a été défavorable avec défaillance multiviscérale et décès 9 jours plus tard. Notre étude rétrospective est l'une des plus grandes séries de cas décrivant les infections à HPIV4, et donne un aperçu global de leur épidémiologie locale. Ces données suggèrent que la prévalence des HPIV4 est probablement sous-estimée. Sa recherche systématique par PCR sur tous les prélèvements respiratoires devrait nous permettre de mieux évaluer et comprendre son épidémiologie. [ABSTRACT FROM AUTHOR]

We report on a long-term monitoring of the cool supergiant Betelgeuse, using the NARVAL and ESPaDOnS high-resolution spectropolarimeters, respectively installed at Telescope Bernard Lyot (Pic du Midi Observatory, France) and at the Canada-France-Hawaii Telescope (Mauna Kea Observatory, Hawaii). The data set, constituted of circularly polarized (Stokes V) and intensity (Stokes I) spectra, was collected between 2010 and 2012. We investigate here the temporal evolution of magnetic field, convection and temperature at photospheric level, using simultaneous measurements of the longitudinal magnetic field component, the core emission of the Ca II infrared triplet, the line-depth ratio of selected photospheric lines and the radial velocity of the star. [ABSTRACT FROM AUTHOR]

The interest in whole-body vibration (WBV) for the enhancement of neuromuscular performance has received considerable attention. However, scientific evidence supporting the optimal prescription of WBV settings is lacking. This study investigated the acute eff ect of WBV combining high frequency/high peak-to-peak displacement (HH) or low frequency/low peakto- peak displacement (LL) vs. sham intervention (SHAM) on lower limb muscle power and stiffness. A total of 223 volunteers were randomly assigned to either the HH, LL or SHAM group. Countermovement jump (CMJ) height, maximal and average power, maximal and average lower limbs stiff ness obtained during a hopping test were recorded before and after the respective intervention. After the intervention, the HH group showed an increase of 4.64 % in CMJ height (p < 0.001) whereas the values of both the LL and SHAM groups did not change. In addition, maximal and average power of the lower limbs were signifi cantly increased in all groups (p < 0.001; 10.89 % and 12.82 %, respectively) while no eff ect on lower limbs stiff ness was observed. Our data show that high frequency combined with high peak-to-peak displacement is the most optimal WBV setting for CMJ height enhancement. Further investigation should be undertaken to ascertain the eff ectiveness of WBV on lower limbs stiff ness. [ABSTRACT FROM AUTHOR]

Abstract: Well defined La–Ni–O oxide structures are prepared by a sol–gel like method and treated at three different temperatures in order to modify their phases and degree of crystallinity, close to that of LaNiO3 perovskite. It is observed that depending on the temperature of the treatment, three crystalline structures (LaNiO3, La2Ni2O5 and La4Ni3O10) are obtained, some of them containing an additional NiO phase. All these structures, characterized by X-ray diffraction and scanning and transmission electron microscopy before reduction, are used for the synthesis of multi-wall carbon nanotubes (MWCNTs) by the catalytic decomposition of methane. The reducibility of each phase under hydrogen is studied by programmed thermo reduction. After reduction and chemical vapor decomposition, inner and outer diameters of the MWCNTs are analyzed. It is found that these characteristics are strongly correlated to the structure of the oxides formed as catalytic precursors. [ABSTRACT FROM AUTHOR]

Whether a whole body vibration session can enhance muscle voluntary activation remains debated. This pilot study thus investigated the acute effects of an intervention with whole body vibration versus a "sham" intervention on the voluntary activation of knee extensor muscles. Ten healthy subjects volunteered to participate in two interventions, vibration and sham, in randomized order. Knee extensor muscle voluntary activation, contractile properties and maximal voluntary isometric contraction were assessed before and immediately after each intervention. No significant differences were found for any of the variables. After both interventions, muscle activation remained unchanged, whereas maximal voluntary isometric contraction was significantly reduced (p<0.05). In conclusion, the two interventions induced the same adaptations in the knee extensors. These findings can be useful in conceiving whole body vibration protocols, although future research is warranted to address the influence of vibration on neural adaptation. [ABSTRACT FROM AUTHOR]

From a set of stellar spectropolarimetric observations, we report the detection of surface magnetic fields in a sample of four solar-type stars, namely HD 73350, HD 76151, HD 146233 (18 Sco) and HD 190771. Assuming that the observed variability of polarimetric signal is controlled by stellar rotation, we establish the rotation periods of our targets, with values ranging from 8.8 d (for HD 190771) to 22.7 d (for HD 146233). Apart from rotation, fundamental parameters of the selected objects are very close to the Sun's, making this sample a practical basis to investigate the specific impact of rotation on magnetic properties of Sun-like stars. We reconstruct the large-scale magnetic geometry of the targets as a low-order spherical harmonic expansion of the surface magnetic field. From the set of magnetic maps, we draw two main conclusions. (i) The magnetic energy of the large-scale field increases with rotation rate. The increase in chromospheric emission with the mean magnetic field is flatter than observed in the Sun. Since the chromospheric flux is also sensitive to magnetic elements smaller than those contributing to the polarimetric signal, this observation suggests that a larger fraction of the surface magnetic energy is stored in large scales as rotation increases. (ii) Whereas the magnetic field is mostly poloidal for low rotation rates, more rapid rotators host a large-scale toroidal component in their surface field. From our observations, we infer that a rotation period lower than ≈12 d is necessary for the toroidal magnetic energy to dominate over the poloidal component. [ABSTRACT FROM AUTHOR]

We investigate the magnetic geometry of the active G8 dwarf ξ Bootis A (ξ Boo A), from spectropolarimetric observations obtained in 2003 with the MuSiCoS échelle spectropolarimeter at the Télescope Bernard Lyot (Observatoire du Pic du Midi, France). We repeatedly detect a photospheric magnetic field, with periodic variations consistent with rotational modulation. Circularly polarized (Stokes V) line profiles present a systematic asymmetry, showing up as an excess in amplitude and area of the blue lobe of the profiles. Direct modelling of Stokes V profiles suggests that the global magnetic field is composed of two main components, with an inclined dipole and a large-scale toroidal field. We derive a dipole intensity of about 40 G, with an inclination of 35° of the dipole with respect to the rotation axis. The toroidal field strength is of the order of 120 G. A noticeable evolution of the field geometry is observed over the 40 nights of our observation window and results in an increase in field strength and dipole inclination. This study is the first step of a long-term monitoring of ξ Boo A and other active solar-type stars, with the aim of investigating secular fluctuations of stellar magnetic geometries induced by activity cycles. [ABSTRACT FROM AUTHOR]

We present spectropolarimetric observations of the FK Com star HD 199178 obtained between 1998 December and 2003 August at the Télescope Bernard Lyot (Observatoire du Pic du Midi, France). We report the detection of a photospheric magnetic field and reconstruct its distribution by means of Zeeman–Doppler imaging. We observe large regions where the magnetic field is mainly azimuthal, suggesting that the dynamo processes generating the magnetic activity of HD 199178 may be active very close to the stellar surface. We investigate the rapid evolution of surface brightness and magnetic structures from a continuous monitoring of the star over several weeks in 2002 and 2003. We report that significant changes occur in the distribution of cool-spots and magnetic regions on typical time-scales of the order of two weeks. Our spectropolarimetric observations also suggest that the surface of HD 199178 is sheared by differential rotation, with a difference in rotation rate between equatorial and polar regions of the order of 1.5 times that of the Sun. [ABSTRACT FROM AUTHOR]

We present here spectropolarimetric observations of the RS CVn system HR 1099 (V711 Tau) secured from 1998 February to 2002 January with the spectropolarimeter MuSiCoS at the Télescope Bernard Lyot (Observatoire du Pic du Midi, France). We apply Zeeman–Doppler imaging and reconstruct surface brightness and magnetic topologies of the K1 primary subgiant of the system, at five different epochs. We confirm the presence of large, axisymmetric regions where the magnetic field is mainly azimuthal, providing further support to the hypothesis that dynamo processes may be distributed throughout the whole convective zone in this star. We study the short-term evolution of surface structures from a comparison of our images with observations secured at close-by epochs by Donati et al. at the Anglo-Australian Telescope. We conclude that the small-scale brightness and magnetic patterns undergo major changes within a time-scale of 4–6 weeks, while the largest structures remain stable over several years. We report the detection of a weak surface differential rotation (both from brightness and magnetic tracers) indicating that the equator rotates faster than the pole with a difference in rotation rate between the pole and the equator about four times smaller than that of the Sun. This result suggests that tidal forces also affect the global dynamic equilibrium of convective zones in cool active stars. [ABSTRACT FROM AUTHOR]

In this paper, we present a new method for measuring the surface differential rotation of cool stars with rotation periods of a few days, for which the sparse phase coverage achievable from single-site observations generally prevents the use of more conventional techniques. The basic idea underlying this new analysis is to obtain the surface differential rotation pattern that minimizes the information content of the reconstructed Doppler image through a simultaneous fit of all available data. Simulations demonstrate that the performance of this new method in the case of cool stars is satisfactory for a variety of observing strategies. Differential rotation parameters can be recovered reliably as long as the total data set spans at least 4 per cent of the time for the equator to lap the pole by approximately one complete cycle. We find in particular that these results hold for potentially complex spot distributions (as long as they include a mixture of low- and high-latitude features), and for various stellar inclination angles and rotation velocities. Such measurements can be obtained from either unpolarized or polarized data sets, provided their signal-to-noise ratio is larger than approximately 500 and 5000 per 2 km s[sup -1] spectral bin, respectively. This method should therefore be very useful for investigating differential rotation in a much larger sample of objects than what has been possible up to now, and should hence give us the opportunity of studying how differential rotation reacts to various phenomena operating in stellar convective zones, such as tidal effects or dynamo magnetic field generation. [ABSTRACT FROM AUTHOR]

We report the characterization of a new insulinotropic compound, 4-hydroxyisoleucine. This amino acid has been extracted and purified from fenugreek seeds, which are known in traditional medicine for their antidiabetic properties. 4-Hydroxyisoleucine increases glucose-induced insulin release, in the concentration range of 100 micromol/l to 1 mmol/l, through a direct effect on isolated islets of Langerhans from both rats and humans. The stimulating effect of 4-hydroxyisoleucine was strictly glucose dependent; indeed, ineffective at low (3 mmol/l) or basal (5 mmol/l) glucose concentrations, the amino acid potentiated the insulin secretion induced by supranormal (6.6-16.7 mmol/l) concentrations of glucose. In addition, in the isolated perfused rat pancreas, we could show 1) that the pattern of insulin secretion induced by 4-hydroxyisoleucine was biphasic, 2) that this effect occurred in the absence of any change in pancreatic alpha- and delta-cell activity, and 3) that the more glucose concentration was increased, the more insulin response was amplified. Moreover, 4-hydroxyisoleucine did not interact with other agonists of insulin secretion (leucine, arginine, tolbutamide, glyceraldehyde). Therefore, we conclude that 4-hydroxyisoleucine insulinotropic activity might, at least in part, account for fenugreek seeds' antidiabetic properties. This secretagogue may be considered as a novel drug with potential interest for the treatment of NIDDM. [ABSTRACT FROM AUTHOR]

Reports on a continuous wave electron spin resonance (ESR) results on the structural phase transformations, phase instabilities and the related kinetics of K[sub 1]C[sub 60]. Origin of the difference between Rb[sub 1]C[sub 60] and K[sub 1]C[sub 60] phase diagrams; Stability of OP-RB[sub 1]C[sub 60]; Narrowness of homogenous cw-ESR linewidth in the temperature range 16-100 Kelvin.

Short-orbit gas giant planet formation/evolution mechanisms are still not well understood. One promising pathway to discriminate between mechanisms is to constrain the occurrence rate of these peculiar exoplanets at the earliest stage of the system's life. However, a major limitation when studying newly born stars is stellar activity. This cocktail of phenomena triggered by fast rotation, strong magnetic fields, and complex internal dynamics, especially present in very young stars, compromises our ability to detect exoplanets. In this paper, we investigated the limitations of such detections in the context of already acquired data solely using radial velocity data acquired with a non-stabilized spectrograph. We employed two strategies: Doppler Imaging and Gaussian Processes and could confidently detect hot Jupiters with a semi-amplitude of 100 m s−1 buried in the stellar activity. We also showed the advantages of the Gaussian Process approach in this case. This study serves as a proof of concept to identify potential candidates for follow-up observations or even discover such planets in legacy data sets available to the community. [ABSTRACT FROM AUTHOR]

Context. This work is part of the BinaMIcS project, the aim of which is to understand the interaction between binarity and magnetism in close binary systems. All the studied spectroscopic binaries targeted by the BinaMIcS project encompass hot massive and intermediate-mass stars on the main sequence, as well as cool stars over a wide range of evolutionary stages. Aims. The present paper focuses on the binary system FK Aqr, which is composed of two early M dwarfs. Both stars are already known to be magnetically active based on their light curves and detected flare activity. In addition, the two components have large convective envelopes with masses just above the fully convective limit, making the system an ideal target for studying effect of binarity on stellar dynamos. Methods. We use spectropolarimetric observations obtained with ESPaDOnS at CFHT in September 2014. Mean Stokes I and V line profiles are extracted using the least-squares deconvolution (LSD) method. The radial velocities of the two components are measured from the LSD Stokes I profiles and are combined with interferometric measurements in order to constrain the orbital parameters of the system. The longitudinal magnetic fields Bl and chromospheric activity indicators are measured from the LSD mean line profiles. The rotational modulation of the Stokes V profiles is used to reconstruct the surface magnetic field structures of both stars via the Zeeman Doppler imaging (ZDI) inversion technique. Results. Maps of the surface magnetic field structures of both components of FK Aqr are presented for the first time. Our study shows that both components host similar large-scale magnetic fields of moderate intensity (Bmean ≃ 0.25 kG); both are predominantly poloidal and feature a strong axisymmetric dipolar component. Conclusions. Both components of FK Aqr feature a rather strong large-scale magnetic field (compared to single early M dwarfs with similar masses) with a mainly dipolar axisymmetric structure. This type of magnetic field is not typical for single early M dwarfs, and is rather reminiscent of fully convective dwarfs with later spectral types. The primary FK Aqr A is currently the most massive recognised main sequence M dwarf known to host this type of strong dipolar field. [ABSTRACT FROM AUTHOR]

We present the results of an analysis aimed at probing the small-scale magnetic fields of M dwarfs observed with SPIRou, the nIR high-resolution spectro-polarimeter installed at the Canada–France–Hawaii Telescope, in the context of the SPIRou Legacy Survey. Our analysis relies on high-resolution median spectra built from several tens of spectra recorded between 2019 and 2022, and on synthetic spectra computed with the ZeeTurbo code for various combination of atmospheric parameters and magnetic field strengths. We pursue the efforts undertaken in a previous study and focus on 44 weakly to moderately active M dwarfs. We derive average magnetic field strengths (< B >) ranging from 0.05 to 1.15 kG, in good agreement with activity estimates and rotation periods. We found that including magnetic fields in our models has virtually no impact on our derived atmospheric parameters, and that a priori assumptions on the stellar surface gravity can affect our estimated < B >. Our results suggest that small-scale magnetic fields account for more than 70 per cent of the overall average magnetic field for most targets whose large-scale fields were previously measured. We derived low magnetic fluxes for several targets in our sample, and found no clear evidence that < B > decreases with increasing Rossby number in the unsaturated dynamo regime. We even identified counterexamples (GJ 1289 and GJ 1286) where the small-scale field is unusually strong despite the long rotation period. Along with similar results on the large-scale fields, our findings further suggest that dynamo processes may operate in a non-conventional mode in these strongly magnetic, slowly rotating stars. [ABSTRACT FROM AUTHOR]

We report results of a spectropolarimetric monitoring of the young Sun-like star V1298 Tau based on data collected with the near-infrared spectropolarimeter SPIRou at the Canada–France–Hawaii Telescope between late 2019 and early 2023. Using Zeeman–Doppler Imaging and the Time-dependent Imaging of Magnetic Stars methods on circularly polarized spectra, we reconstructed the large-scale magnetic topology of the star (and its temporal evolution), found to be mainly poloidal and axisymmetric with an average strength varying from 90 to 170 G over the ∼3.5 yr of monitoring. The magnetic field features a dipole whose strength evolves from 85 to 245 G, and whose inclination with respect to the stellar rotation axis remains stable until 2023 where we observe a sudden change, suggesting that the field may undergo a polarity reversal, potentially similar to those periodically experienced by the Sun. Our data suggest that the differential rotation shearing the surface of V1298 Tau is about 1.5 times stronger than that of the Sun. When coupling our data with previous photometric results from K2 and TESS and assuming circular orbits for all four planets, we report a 3.9σ detection of the radial velocity signature of the outermost planet (e), associated with a most probable mass, density, and orbital period of |$M_\mathrm{e}=0.95^{+0.33}_{-0.24}$| MꝜ, |$\rho _\mathrm{e}=1.66^{+0.61}_{-0.48}$| |$\rm g\, cm^{-3}$|⁠ , and P e = 53.0039 ± 0.0001 d, respectively. For the three inner planets, we only derive 99 per cent confidence upper limits on their mass of 0.44, 0.22, and 0.25 MꝜ, for b, c, and d, respectively. [ABSTRACT FROM AUTHOR]

We present near-infrared spectropolarimetric observations of a sample of 43 weakly to moderately active M dwarfs, carried with SPIRou at the Canada–France–Hawaii Telescope in the framework of the SPIRou Legacy Survey from early 2019 to mid-2022. We use the 6700 circularly polarised spectra collected for this sample to investigate the longitudinal magnetic field and its temporal variations for all sample stars, from which we diagnose, through quasi-periodic Gaussian process regression, the periodic modulation and longer-term fluctuations of the longitudinal field. We detect the large-scale field for 40 of our 43 sample stars, and infer a reliable or tentative rotation period for 38 of them, using a Bayesian framework to diagnose the confidence level at which each rotation period is detected. We find rotation periods ranging from 14 to over 60 d for the early-M dwarfs, and from 70 to 200 d for most mid- and late-M dwarfs (potentially up to 430 d for one of them). We also find that the strength of the detected large-scale fields does not decrease with increasing period or Rossby number for the slowly rotating dwarfs of our sample as it does for higher-mass, more active stars, suggesting that these magnetic fields may be generated through a different dynamo regime than those of more rapidly rotating stars. We also show that the large-scale fields of most sample stars evolve on long time-scales, with some of them globally switching sign as stars progress on their putative magnetic cycles. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to evaluate the efficacy and safety of radiofrequency ablation (RFA) in the management of haemorrhoidal disease with 1 year's follow-up. Method: This prospective multicentre study assessed RFA (Rafaelo©) in outpatients with grade II–III haemorrhoids. RFA was performed in the operating room under locoregional or general anaesthesia. Primary endpoint was the evolution of a quality-of-life score adapted to the haemorrhoid pathology (HEMO-FISS-QoL) 3 months after surgery. Secondary endpoints were evolution of symptoms (prolapsus, bleeding, pain, itching, anal discomfort), complications, postoperative pain and medical leave. Results: A total of 129 patients (69% men, median age 49 years) were operated on in 16 French centres. Median HEMO-FISS-QoL score dropped significantly from 17.4/100 to 0/100 (p < 0.0001) at 3 months. At 3 months, the rate of patients reporting bleeding (21% vs. 84%, p < 0.001), prolapse (34% vs. 91.3%, p < 0.001) and anal discomfort (0/10 vs. 5/10, p < 0.0001) decreased significantly. Median medical leave was 4 days [1–14]. Postoperative pain was 4/10, 1/10, 0/10 and 0/10 at weeks 1, 2, 3 and 4. Seven patients (5.4%) were reoperated on by haemorrhoidectomy for relapse, and three for complications. Reported complications were haemorrhage (3), dysuria (3), abscess (2), anal fissure (1), external haemorrhoidal thrombosis (10), pain requiring morphine (11). Degree of satisfaction was high (+ 5 at 3 months on a − 5/+ 5 scale). Conclusion: RFA is associated with an improvement in quality of life and symptoms with a good safety profile. As expected for minimally invasive surgery, postoperative pain is minor with short medical leave. Clinical trial registration and date: Clinical trial NCT04229784 (18/01/2020). [ABSTRACT FROM AUTHOR]

In this work, we simulate the evolution of the solar wind along its main-sequence lifetime and compute its thermal radio emission. To study the evolution of the solar wind, we use a sample of solar mass stars at different ages. All these stars have observationally reconstructed magnetic maps, which are incorporated in our 3D magnetohydrodynamic simulations of their winds. We show that angular-momentum loss and mass-loss rates decrease steadily on evolutionary time-scales, although they can vary in a magnetic cycle time-scale. Stellar winds are known to emit radiation in the form of thermal bremsstrahlung in the radio spectrum. To calculate the expected radio fluxes from these winds, we solve the radiative transfer equation numerically from first principles. We compute continuum spectra across the frequency range 100 MHz to 100 GHz and find maximum radio flux densities ranging from 0.05 to 2.2 |$\mu$| Jy. At a frequency of 1 GHz and a normalized distance of d  = 10 pc, the radio flux density follows 0.24 (Ω/Ω⊙)0.9 (d /[10pc])-2 |$\mu$| Jy, where Ω is the rotation rate. This means that the best candidates for stellar wind observations in the radio regime are faster rotators within distances of 10 pc, such as κ1 Ceti (0.73 |$\mu$| Jy) and χ1 Ori (2.2 |$\mu$| Jy). These flux predictions provide a guide to observing solar-type stars across the frequency range 0.1–100 GHz in the future using the next generation of radio telescopes, such as ngVLA and Square Kilometre Array. [ABSTRACT FROM AUTHOR]

Editorial. Looks at the probable role of endonuclease G, a protein of the pro-apoptotic family, in causing cell death. Effect of mitochondrial damage in the dysregulation of its ancestral toxin/antitoxin component with consequent cell death; Involvement of endonuclease G in nuclear DNA disagregation; Need to know whether endonuclease G can cause death by itself.

We report first results on a method aimed at simultaneously characterizing atmospheric parameters and magnetic properties of M dwarfs from high-resolution near-IR spectra recorded with SPIRou in the framework of the SPIRou Legacy Survey (SLS). Our analysis relies on fitting synthetic spectra computed from marcs model atmospheres to selected spectral lines, both sensitive and insensitive to magnetic fields. We introduce a new code, ZeeTurbo , obtained by including the Zeeman effect and polarized radiative transfer capabilities to Turbospectrum. We compute a grid of synthetic spectra with ZeeTurbo for different magnetic field strengths and develop a process to simultaneously constrain T eff, log  g , |$\rm {[M/H]}$|⁠ , |$\rm {[\alpha /Fe]}$|⁠ , and the average surface magnetic flux. In this paper, we present our approach and assess its performance using simulations, before applying it to six targets observed in the context of the SLS, namely AU Mic, EV Lac, AD Leo, CN Leo, PM J18482+0741, and DS Leo. Our method allows us to retrieve atmospheric parameters in good agreement with the literature, and simultaneously yields surface magnetic fluxes in the range 2–4 kG with a typical precision of 0.05 kG, in agreement with literature estimates, and consistent with the saturated dynamo regime in which most of these stars are. [ABSTRACT FROM AUTHOR]

F stars lie in the transition region between cool stars with dynamo generated fields and hot star fossil fields and offer an interesting window into the generation of magnetic fields in shallow convection zones. In this paper, we investigate the magnetic field of the mature F7V primary of the bright χ Draconis system. χ Dra was observed in circularly polarized light at four epochs from 2014 through to 2019 using the NARVAL spectropolarimeter at the Téléscope Bernard Lyot. Using the technique of least-squares deconvolution, we created high signal-to-noise line profiles from which we were able to measure the radial velocity of both the primary and secondary and use these to improve the orbital parameters of the system. Additionally, we used the technique of Zeeman Doppler imaging to reconstruct the large-scale magnetic field geometry of the primary at the four epochs. The magnetic maps show that χ Dra A has a predominately dipolar poloidal magnetic field at all epochs with the magnetic axis well aligned with the stellar rotation axis. The large-scale features of the magnetic field appear to be relatively stable over the ∼5 yr time base of our observations, with no evidence of any polarity reversals. We used the magnetic field maps to model the wind from χ Dra A at all epochs, showing that the mass-loss from the stellar wind of χ Dra A is 3–6 times the current solar value, while the angular momentum loss from the wind is around 3–4 times the solar value. [ABSTRACT FROM AUTHOR]

The origin of magnetic fields and their role in chemical spot formation on magnetic Ap stars is currently not understood. Here, we contribute to solving this problem with a detailed observational characterization of the surface structure of 45 Her, a weak-field Ap star. We find this object to be a long-period, single-lined spectroscopic binary and determine the binary orbit as well as fundamental and atmospheric parameters of the primary. We study magnetic field topology and chemical spot distribution of 45 Her with the help of the Zeeman Doppler imaging technique. Magnetic mapping reveals the stellar surface field to have a distorted dipolar topology with a surface-averaged field strength of 77 G and a dipolar component strength of 119 G – confirming it as one of the weakest well-characterized Ap-star fields known. Despite its feeble magnetic field, 45 Her shows surface chemical inhomogeneities with abundance contrasts of up to 6 dex. Of the four chemical elements studied, O concentrates at the magnetic equator, whereas Ti, Cr, and Fe avoid this region. Apart from this trend, the positions of Fe-peak element spots show no apparent correlation with the magnetic field geometry. No signs of surface differential rotation or temporal evolution of chemical spots on the time-scale of several years were detected. Our findings demonstrate that chemical spot formation does not require strong magnetic fields to proceed and that both the stellar structure and the global field itself remain stable for sub-100 G field strengths contrary to theoretical predictions. [ABSTRACT FROM AUTHOR]

A Li-rich lamellar oxide was cycled at high potential and the relevance of using a constant voltage step (CVS) at the end of the charge, needed for industrial application, was investigated by electrochemical performance, X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM). Electrochemical studies at 4.7 and 4.5 V with and without CVS showed that capacity and voltage fading occurred mostly when cells operated at high potential. After cycling, 3D-type defects involving transition metals trapped in lithium layer were observed by HRTEM into the electrode bulk. These defects are responsible for the voltage fading. XRD microstrain parameter was used to evaluate defects rate in aged materials subjected to a CVS, showing more 3D-type defects when cycled at 4.7 V than at 4.5 V. The time spent at high potential at the end of the charge as well as the value of the upper potential limit, are both relevant parameters to voltage decay. The use of a CVS at the end of the charge needs at the same time, a reduced upper potential window in order to minimize 3D-type defects occurrence. Unfortunately, this approach is still not sufficient to prevent voltage fading. [ABSTRACT FROM AUTHOR]

There is a large change in surface rotation rates of sun-like stars on the pre-main sequence and early main sequence. Since these stars have dynamo-driven magnetic fields, this implies a strong evolution of their magnetic properties over this time period. The spin-down of these stars is controlled by interactions between stellar and magnetic fields, thus magnetic evolution in turn plays an important role in rotational evolution. We present here the second part of a study investigating the evolution of large-scale surface magnetic fields in this critical time period. We observed stars in open clusters and stellar associations with known ages between 120 and 650 Myr, and used spectropolarimetry and Zeeman Doppler Imaging to characterize their large-scale magnetic field strength and geometry. We report 15 stars with magnetic detections here. These stars have masses from 0.8 to 0.95 M⊙, rotation periods from 0.326 to 10.6 d, and we find large-scale magnetic field strengths from 8.5 to 195G with a wide range of geometries. We find a clear trend towards decreasing magnetic field strength with age, and a power law decrease in magnetic field strength with Rossby number. There is some tentative evidence for saturation of the large-scale magnetic field strength at Rossby numbers below 0.1, although the saturation point is not yet well defined. Comparing to younger classical T Tauri stars, we support the hypothesis that differences in internal structure produce large differences in observed magnetic fields, however for weak-lined T Tauri stars this is less clear. [ABSTRACT FROM AUTHOR]

La neurostimulation trans-cutanée consiste à délivrer un courant électrique via des électrodes appliquées sur la peau. Son utilisation est recommandée pour le traitement des douleurs radiculaires neuropathiques. Le courant peut être délivré à haute fréquence-basse intensité (mode conventionnel « c-TENS »), à basse fréquence-haute intensité (mode endorphinique) ou selon un mode associant ces 2 types de courant (mode mixte « m-TENS »). Toutefois, aucune donnée ne permet de privilégier l'un par rapport à l'autre. L'objectif de cette étude était de comparer l'efficacité et la tolérance de 2 modes de stimulation : c-TENS et m-TENS. Il s'agit d'une étude prospective, multicentrique, randomisée, en cross-over. Les patients inclus devaient présenter une radiculalgie chronique (durée ≥ 3 mois), neuropathique (score dn4 ≥ 4), et d'intensité au moins modérée (échelle EVA ≥ 40/100 mm). Ils étaient randomisés pour recevoir la neurostimulation soit par c-TENS pendant 1 mois, puis par m-TENS le mois suivant, soit dans l'ordre inverse. Les traitements antalgiques associés ne devaient pas être modifiés. Le critère de jugement principal était l'EVA à un mois de chaque traitement. Passés ces 2 mois, les patients pouvaient choisir de poursuivre ou non la neurostimulation, selon le mode de leur choix. Une nouvelle évaluation était réalisée à 6 mois. Soixante-quatorze patients ont été inclus. L'analyse a pu porter sur 64 patients (analyse en ITT). L'âge moyen était de 51,9 ans (±13,5). La radiculalgie concernait le membre inférieur chez 49 patients (76,6 %) et le membre supérieur chez 15 patients (23,4 %). Elle évoluait depuis 45,2 mois (±51). L'EVA douleur initiale était de 67 mm (±12,5). Après 1 mois de traitement, l'EVA passait à 53,9 mm (±20,1) sous c-TENS et également à 53,9 mm (±21,3) sous m-TENS, soit une différence nulle (±16,2) (p = 1) ; une amélioration significative (score d'impression globale de changement PGIC ≥ 5) était rapportée par 25 patients (39,7 %) sous c-TENS et par 26 patients (40,6 %) sous m-TENS, soit une absence d'impact apparent du mode sur ce critère également (p = 1). La tolérance était comparable entre les 2 modes, avec très peu événements indésirables, tous mineurs et pour la plupart locaux (en regard des zones d'application des électrodes). Après expérimentation des 2 modes de stimulation, les patients ayant exprimé une préférence ont désigné pour 34 d'entre eux le m-TENS (54 %) et pour 29 (46 %) le c-TENS. Cinquante-neuf patients ont effectué la visite à M6 et 50 (84,7 %) poursuivaient la neurostimulation à cette date. L'essai en cross-over utilise le patient comme son propre témoin, permettant ainsi de s'affranchir de la variabilité inter-patient. Nos résultats suggèrent que le mode de stimulation n'est pas un critère ayant une influence significative sur l'efficacité du TENS. Plus généralement, on observe que moins de la moitié des patients estime significative l'amélioration obtenue, mais qu'une très large majorité désire poursuivre le traitement après la période test. Cette étude ne montre pas de différence en termes d'efficacité ou de tolérance entre une neurostimulation sur un mode conventionnel et un mode associant mode conventionnel et mode endorphinique. Il n'y a pas de raison apparente de privilégier un de ces 2 modes dans les radiculalgies neuropathiques. [ABSTRACT FROM AUTHOR]

Abstract: Vascular lesions of the hand are challenging for diagnosis and treatment. These lesions are far more common than malignant tumors. Clinical presentation may be confusing and correct identification by imaging is sometimes mandatory. Standard X-rays and doppler ultrasound examination are the first modalities to be used. Doppler ultrasound help to characterize the lesion or/and to assess the flow velocity within the lesion. It allows to separate the high flow lesions (hemangioma, arteriovenous malformation) from the low or no flow lesions (venous malformation, cystic lymphangioma). MR imaging is the gold examination to define the size and the extension of the lesion to adjacent structures. Careful clinical and imaging evaluation and multidisciplinary staff decision are crucial before to propose embolotherapy and/or surgical treatment. In case of persistent doubt, a biopsy must be required. AVM must be excluded before to propose this biopsy sample. Interventional radiology can be used alone or in combination with surgery to treat vascular malformation (arteriovenous, lymphatic, venous, or mixed). Embolisation may either be done by percutaneous approach (all malformations) or by intravascular catheterization (arteriovenous malformation). Hemangioma is a benign tumor which most often spontaneously involutes with age. Vascular malformations of the hand are difficult to eradicate completely either with embolization or surgery or both. Recurrences are frequent. Management in multidisciplinary staff is mandatory and long follow-up is needed. [Copyright &y& Elsevier]

Spectropolarimetric data allow for simultaneous monitoring of stellar chromospheric |$\log {R^{\prime }_{\rm {HK}}}$| activity and the surface-averaged longitudinal magnetic field, Bl , giving the opportunity to probe the relationship between large-scale stellar magnetic fields and chromospheric manifestations of magnetism. We present |$\log {R^{\prime }_{\rm {HK}}}$| and/or Bl measurements for 954 mid-F to mid-M stars derived from spectropolarimetric observations contained within the PolarBase database. Our magnetically active sample complements previous stellar activity surveys that focus on inactive planet-search targets. We find a positive correlation between mean |$\log {R^{\prime }_{\rm {HK}}}$| and mean log | Bl |, but for G stars the relationship may undergo a change between |$\log {R^{\prime }_{\rm {HK}}}\sim -4.4$| and −4.8. The mean |$\log {R^{\prime }_{\rm {HK}}}$| shows a similar change with respect to the |$\log {R^{\prime }_{\rm {HK}}}$| variability amplitude for intermediately active G stars. We also combine our results with archival chromospheric activity data and published observations of large-scale magnetic field geometries derived using Zeeman–Doppler Imaging. The chromospheric activity data indicate a slight under-density of late-F to early-K stars with |$-4.75\le \log {R^{\prime }_{\rm HK}}\le -4.5$|⁠. This is not as prominent as the original Vaughan–Preston gap, and we do not detect similar under-populated regions in the distributions of the mean | Bl |, or the Bl and |$\log {R^{\prime }_{\rm HK}}$| variability amplitudes. Chromospheric activity, activity variability, and toroidal field strength decrease on the main sequence as rotation slows. For G stars, the disappearance of dominant toroidal fields occurs at a similar chromospheric activity level as the change in the relationships between chromospheric activity, activity variability, and mean field strength. [ABSTRACT FROM AUTHOR]

This paper presents a practical method to detect any accidental partial shadowing on an operating photovoltaic (PV) panel in a smart generation system including a control center. Given a known solar irradiance level and temperature it is possible to make an automatic estimation of the output electrical power and to trigger an alarm in case of an accidental shadowing occurrence. Preliminary field measurements data are taken to evaluate the PV panel parameters once and for all. Simulation of the panel in operation is performed with the mathematical method of Design of Experiments (DoE): the maximum power parameter is considered as critical for the protection and security of the PV panel. Its value is computed and any amount of partial shadowing is then detected from the difference between the measured and the calculated values of this parameter. This method can be easily implemented in any smart PV generation system as an alarm trigger in actual operation to insure complete safety of the generation system. [ABSTRACT FROM AUTHOR]

In this paper, a comparison is made of the economical viability in South Africa of horizontal-ground-source systems and air-source systems. This study is undertaken because South African manufacturers of air-source systems are considering producing ground-source systems, since the latter systems are gaining more acceptance for environmental reasons. Monthly heating/cooling capacities and coefficients of performance for both systems are determined. Furthermore, it is found that overseas data concerning the optimum depth for the placement of a horizontal water-loop for a ground-source system are not valid for SouthAfrican conditions, due to climatic differences. Therefore, a techno-economic analysis is conducted to determine the optimum depth. The payback period, net present value and internal rate of return of ground-source systems at various depths are calculated for Pretoria, SouthAfrica. It is conclude that ground-source systems are more viable than air-source systems. It is also observed that the optimum depth forthe horizontal water-loop is very shallow compared to recommendations in literature. [ABSTRACT FROM AUTHOR]