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A semi-analytical study of the steady flow around a spherical particle rotating in an incompressible Newtonian fluid inside an eccentric spherical cavity with slip surfaces about their common diameter is presented at low Reynolds numbers. To solve the Stokes equation, a solution consisting of the general solutions in two systems of spherical coordinates is employed and the boundary conditions are fulfilled by a collocation method. Accurate results of the torque exerted by the fluid on the particle are obtained as a function of the dimensionless parameters a ∕ b , d ∕ ( b − a ) , β a ∕ η , and β w b ∕ η , where a and b are the radii and β − 1 and β w − 1 are the Navier slip coefficients of the particle and cavity, respectively, d is the distance between the particle and cavity centers, and η is the fluid viscosity. The boundary effect of the cavity with a slip wall on the rotation of the slip particle is quite significant and interesting. The torque normalized by that on the particle in an unbounded identical fluid vanishes as β w b ∕ η = 0 (the cavity wall is fully slip), equals unity for a value of β w b ∕ η very close to 3, and in general increases with an increase in β w b ∕ η (or the stickiness of the cavity wall). When β w b ∕ η > 3 , the normalized torque is in general greater than unity, an increasing/decreasing function of the eccentricity parameter d ∕ ( b − a ) if the value of β a ∕ η (or the stickiness of the particle surface) is large/small, and an increasing function of β a ∕ η and a ∕ b . When β w b ∕ η 3 , conversely, the normalized torque is in general less than unity, a decreasing/increasing function of d ∕ ( b − a ) if the value of β a ∕ η is large/small, and a decreasing function of β a ∕ η and a ∕ b . The cavity wall exerts less torque on the particle when it rotates about their common diameter than about an axis normal to it.

We investigate the possibility of a supernova in supermassive (5 × 104 M⊙) population III stars induced by a general relativistic instability occurring in the helium burning phase. This explosion could occur via rapid helium burning during an early contraction of the isentropic core. Such an explosion would be visible to future telescopes and could disrupt the proposed direct collapse formation channel for early Universe supermassive black holes. We simulate first the stellar evolution from hydrogen burning using a 1D stellar evolution code with a post-Newtonian approximation; at the point of dynamical collapse, we switch to a 1D (general relativistic) hydrodynamic code with the Misner-Sharpe metric. In opposition to a previous study, we do not find an explosion in the non-rotating case, although our model is close to exploding for a similar mass to the explosion in the previous study. When we include slow rotation, we find one exploding model, and we conclude that there likely exist additional exploding models, though they may be rare.

International audience; Sterically hindered aminoarylboranes featuring atropisomerism about the C-B bond were prepared by addition of organomagnesium species onto readily accessible dialkylamine-borane complexes. Some of these aminoarylboranes, isosteres of vinyl styrene derivatives, were resolved by HPLC on chiral stationary phase. They are the first examples of non-biaryl type system which display slow rotation about a C-B bond.

In the Bavarian Molasse Basin, especially in the greater Munich, geothermal exploration of the hydrothermal Upper Jurassic reservoir is rapidly expanding. Until now, little seismic reservoir response is observed, only at two out of 16 sites seismic events with M L > 2.0 were detected: at Unterhaching, in 2008, six events with M L > 2 occurred soon after the onset of circulation; at Poing, in 2016, 5 years after circulation started, two events with ML∼2.1 occurred, both located near the injection well. The analysis of the reactivation potential allows to connect seismicity to fault structures. In the Bavarian Molasse Basin, fault structures generally exhibit low seismic reactivation potential, as long as they trend ENE-WSW. By Monte-Carlo simulation, the geological uncertainty and the sensitivity of the individual parameters are quantified. They show that critically pre-stressed fault segments, e.g. at Unterhaching, combined with minimum change of the hydraulic reservoir conditions can lead to a dramatic increase of the reactivation potential of seismicity. For uncritical fault segments, e.g. at the Poing site, two self-enforcing effects are discussed which increase the reactivation potential over time: first, stress field modification by thermo-hydraulic effects and, second, fault alteration by carbonate dissolution can reduce the fault friction and cohesion. Both effects increase the sensitivity of the reactivation potential to the fault friction and can bring previously uncritical fault segments to critical state. Finally, the possible impact of coupled thermo-hydro-mechanical and chemical processes at hydrothermal systems on the reactivation potential is highlighted: at fault segments with high reactivation potential hydro-mechanical effects may dominate whereas at low reactivation potential thermo-mechanical processes can potentially yield to a slow rotation of the stress field.

The first FORS2 spectropolarimetric observation of the longitudinal magnetic field of HD54879 of the order of -600G with a lower limit of the dipole strength of ~2kG dates back to 2014. Since then observations showed a gradual decrease of the absolute value of the mean longitudinal magnetic field. In the course of the most recent monitoring of HD54879 using FORS2 spectropolarimetric observations from 2017 October to 2018 February, a longitudinal magnetic field strength change from about -300G down to about -90G was reported. A sudden increase of the absolute value of the mean longitudinal magnetic field and an accompanying spectral variability was detected on 2018 February 17. New FORS2 spectropolarimetric data obtained from 2018 December to 2019 February confirm the very slow magnetic field variability, with the field decreasing from about 150G to -100G over two months. Such a slow magnetic field variability, related to the extremely slow rotation of HD54879, is also confirmed using high-resolution HARPSpol and ESPaDOnS spectropolarimetry. The re-analysis of the FORS2 polarimetric spectra from 2018 February indicates that the previously reported field increase and the change of the spectral appearance was caused by improper spectra extraction and wavelength calibration using observations obtained at an insufficient signal-to-noise ratio. The presented properties of HD54879 are discussed in the context of the Of?p spectral classification., Comment: 8 pages, 2 tables, 11 figures, accepted for publication in MNRAS

We have investigated effect of geometric optics as the rotation of polarization vector of light in spacetime of gravitational compact object in the fourth-order theory of conformal Weyl gravity. The Pineault–Roeder method is applied to the rotating Weyl metric, and analytical results are obtained in the limit of weak field and or slow rotation. For the photon traveling parallel to the symmetry axes from the equatorial plane to infinity, the rotation of the polarization plane depends on the Weyl parameter $$\gamma $$ γ on the contrary to the Kerr spacetime where there is no rotation of polarization plane for this case.

10-Hydrazino-BODIPY, BoNHNH2, presents slow rotation about the C10–NH bond that results in anisochronous 1H and 13C NMR signals. The assignment of the different signals has been made using traditional two-dimensional methods as well as spin–spin coupling constants and confirmed by DFT calculations (B3LYP) using the 6-311++G(d,p) basis set. The rotational barrier has been determined in three pairs of proton signals and compared with the calculated barrier., Comunidad de Madrid, Grant/Award Number: P2018/EMT-4329 AIRTEC-CM; Consejo Nacional de Ciencia y Tecnología, Grant/Award Number: 253623, and 123732; DAIP, Grant/Award Number: 2020; Ministerio de Ciencia, Innovación y Universidades, Grant/Award Number: PGC2018-094644-B-C22

Background Sleep technicians are at high risk of shift work sleep disorders. We therefore aimed to identify the optimal shift system for sleep technicians. Methods We performed a nationwide survey of the work schedules, health and quality of life of sleep technicians using e-mail questionnaires including the Insomnia Severity Index (ISI), Epworth Sleep Scale (ESS), Functional Outcomes of Sleep Questionnaire-10 (FOSQ-10), Short Form-12 Health Survey (SF-12), and Hospital Anxiety and Depression Scale (HADS) in Korea. A multivariate general linear model was used to assess the effect of shift schedules on health and quality of life. Results Fifty-four technicians from 30 sleep laboratories participated. Their work schedules were classified as fixed night (F) (n = 18), slow rotation alternating from a night-only to a day-only schedule with a 3-months to one-year interval (S) (n = 20), rapid rotation within a week (R) (n = 5), night once a week (D+) (n = 5) and day (D) (n = 6). The adjusted ISI and HADS-anxiety scores were higher in F, S, and R than D and D+. Among night shift-dominant schedules, a less favorable profile was observed for R followed by F, and S regarding the ISI, FOSQ-10, mental SF-12 and HADS-depression. The physical SF-12 was lower in the order of R, S and F. The HADS-anxiety score was higher in the order of F, R and S. Conclusions The S system appears to have the least negative effect on health and quality of life among night shift-dominant systems. The development of consensus guidelines for scheduling shifts in sleep laboratories is urged.

Bis(methylene)-λ4-selane 1, which represents a new class of heteroallenes, was synthesized and isolated as a stable purple crystalline solid. X-ray crystallographic analysis revealed a bent allene-type structure with pseudo C2v symmetry and a bent C[double bond, length as m-dash]Se[double bond, length as m-dash]C moiety that contains a 3-center-4-electron π-bond. The NMR spectrum of 1 shows compelling evidence for a slow rotation of the Se[double bond, length as m-dash]C moieties at room temperature. The 77Se NMR spectrum of 1 contains one signal in the region characteristic for Se(iv) compounds.

The evolution and the characteristic features of double layers in a plasma under slow rotation and contaminated with dust grains with varying charges under the effect of an external magnetic field are studied. The Coriolis force resulting from the slow rotation is responsible for the generation of an equivalent magnetic field. A comparatively new pseudopotential approach has been used to derive the small amplitude double layers. The effect of the relative electron-ion concentration, as well as the temperature ratio, on the formation of the double layers has also been investigated. The study reveals that compressive, as well as rarefactive, double layers can be made to co-exist in plasma by controlling the dust charge fluctuation effect supplemented by variations of the plasma constituents. The effectiveness of slow rotation in causing double layers to exist has also emanated from the study. The results obtained could be of interest because of their possible applications in both laboratories and space.

When NASA announced it would spend $1 billion developing two new missions to Venus—the agency9s first visits in decades to Earth9s hothouse twin—planetary scientists were elated, and not just because a long wait had ended. A dramatic shift in thinking about the planet over the past few years has made a visit even more enticing. Venus was once thought to have boiled off all its water almost as soon as it was born 4.5 billion years ago, turning into the parched, hostile world of today. But recent climate modeling has now suggested the planet9s slow rotation would allow planet-spanning cloud decks to form, reflecting the Sun9s attack and allowing Venus to host expansive oceans for billions of years—a nearly perfect setting for life. The two spacecraft, both selected as part of NASA9s Discovery line of competed missions, will arrive later this decade, scouring the surface and atmosphere for signs of past water and plate tectonics—and clues to why Venus ultimately declined into an inferno.

The genesis potential index (GPI) of tropical cyclones (TC) on ocean planets in the habitable zones of M dwarfs is analyzed based on 3D GCM simulations. We found that GPI on these planets are smaller than those in TC basins on the Earth mainly because of slow rotation of such planets. GPI's on exoplanets with eccentric orbits are strong function of time with values generally greater than those on circular orbits. Future high resolution models are needed to better understand whether TCs could form on ocean exoplanets, and what their potential intensities and distributions might be.

In this paper, we present an analytical calculation of the rotational mobility functions of a particle rotating on the centerline of an elastic cylindrical tube whose membrane exhibits resistance towards shearing and bending. We find that the correction to the particle rotational mobility about the cylinder axis depends solely on membrane shearing properties while both shearing and bending manifest themselves for the rotational mobility about an axis perpendicular to the cylinder axis. In the quasi-steady limit of vanishing frequency, the particle rotational mobility nearby a no-slip rigid cylinder is recovered only if the membrane possesses a non-vanishing resistance towards shearing. We further show that for the asymmetric rotation along the cylinder radial axis, a coupling between shearing and bending exists. Our analytical predictions are compared and validated with corresponding boundary integral simulations where a very good agreement is obtained., 23 pages, 7 figures and 107 references. Revised manuscript resubmitted to Acta Mech

The Kerr spacetime is perhaps the most astrophysically important of the currently known exact solutions to the Einstein field equations. Whenever spacetimes can be put in unit-lapse form it becomes possible to identify some very straightforward timelike geodesics, (the "rain" geodesics), making the physical interpretation of these spacetimes particularly clean and elegant. The most well-known of these unit-lapse formulations is the Painleve-Gullstrand form of the Schwarzschild spacetime, though there is also a Painleve-Gullstrand form of the Lense-Thirring (slow rotation) spacetime. More radically there are also two known unit-lapse forms of the Kerr spacetime -- the Doran and Natario metrics -- though these are not precisely in Painleve-Gullstrand form. Herein we shall seek to explicate the most general unit-lapse form of the Kerr spacetime. While at one level this is "merely" a choice of coordinates, it is a strategically and tactically useful choice of coordinates, thereby making the technically challenging but astrophysically crucial Kerr spacetime somewhat easier to deal with., Comment: 29 pages

The C-arm perfusion imaging is not yet the standard part for liver cancer diagnosis and intraoperative measurements. The number of multiple rotations of C-arm depends on the total angle range resulting in large number of projections. Usually most of the liver disease features can be visible on CT images. However, the breathing and other liver surrounding organs motion during the acquisition can cause artifacts or missing important data on reconstructed CT images. In C-arm systems this is the consequence of the slow rotation. This paper gives an overview of existing motion correction algorithms used in medical imaging. These algorithms are based on image segmentation and registration.

The aims of this study were to develop a technique for the extraction of cortisol from sturgeon fins using two washing solvents (water and isopropanol) and quantify any differences in fin cortisol levels among three main sturgeon species. Fins were harvested from 19 sacrificed sturgeons including seven beluga (Huso huso), seven Siberian (Acipenser baerii), and five sevruga (A. stellatus). The sturgeons were raised in Iranian farms for 2 years (2017-2018), and cortisol extraction analysis was conducted in South Korea (January-February 2019). Jawbones from five H. huso were also used for cortisol extraction. Data were analyzed using the general linear model (GLM) procedure in the SAS environment. The intra- and inter-assay coefficients of variation were 14.15 and 7.70, respectively. Briefly, the cortisol extraction technique involved washing the samples (300 ± 10 mg) with 3 mL of solvent (ultrapure water and isopropanol) twice, rotation at 80 rpm for 2.5 min, air-drying the washed samples at room temperature (22-28 °C) for 7 days, further drying the samples using a bead beater at 50 Hz for 32 min and grinding them into powder, applying 1.5 mL methanol to the dried powder (75 ± 5 mg), and slow rotation (40 rpm) for 18 h at room temperature with continuous mixing. Following extraction, samples were centrifuged (9,500 x g for 10 min), and 1 mL supernatant was transferred into a new microcentrifuge tube (1.5 mL), incubated at 38 °C to evaporate the methanol, and analyzed via enzyme-linked immunosorbent assay (ELISA). No differences were observed in fin cortisol levels among species or in fin and jawbone cortisol levels between washing solvents. The results of this study demonstrate that the sturgeon jawbone matrix is a promising alternative stress indicator to solid matrices.

Many navigating insects include the celestial polarization pattern as an additional visual cue to orient their travels. Spontaneous orientation responses of both walking and flying fruit flies (Drosophila melanogaster) to linearly polarized light have previously been demonstrated. Using newly designed modular flight arenas consisting entirely of off-the-shelf parts and 3D-printed components we present individual flying flies with a slow and continuous rotational change in the incident angle of linear polarization. Under such open-loop conditions, single flies choose arbitrary headings with respect to the angle of polarized light and show a clear tendency to maintain those chosen headings for several minutes, thereby adjusting their course to the slow rotation of the incident stimulus. Importantly, flies show the tendency to maintain a chosen heading even when two individual test periods under a linearly polarized stimulus are interrupted by an epoch of unpolarized light lasting several minutes. Finally, we show that these behavioral responses are wavelength-specific, existing under polarized UV stimulus while being absent under polarized green light. Taken together, these findings provide further evidence supporting Drosophila’s abilities to use celestial cues for visually guided navigation and course correction.

Este es el post-print que se ha publicado de forma definitiva en: https://pubs.rsc.org/en/content/articlelanding/2017/ob/c6ob02618d#!divAbstract By comparison with close contact interactions between benzene rings there is a paucity of experimental data available for attractive interactions involving aromatic heterocyclic rings, especially for small molecules in solution. Herein we describe aromatic heterocyclic and carbocyclic edge-to face interactions and conformational stereodynamics of N-1,2-diphenylethyl imines bearing a phenyl group and either a 2-pyridyl, 3-pyridyl, 2-thiophene or 2-furanyl moiety on the imino carbon. X-ray crystal structures have been determined for two compounds. Slow rotation about the phenyl–imino bond in the E-isomers and around the heterocycle–imino bond in the Z-isomers of the pyridyl compounds was observed at low temperatures by NMR. Abnormally large shielding of one ortho hydrogen indicates that both the imino phenyl and heterocycle rings can engage in an edge-to-face interaction with the N-terminal phenyl moiety in the appropriate isomer. Some rotational barriers around the phenyl–imino and heterocycle–imino bonds were measured. This is the peer reviewed version of the following article: González-Rosende, ME., Castillo García, E., Jennings, WB. & Malone, JF. (2017). Stereodynamics and Edge-to-Face CH-π aromatic interactions in imino compounds containing heterocyclic rings. Organic & Biomolecular Chemistry, n. 6, which has been published in final form at https://doi.org/10.1039/C6OB02618D. Esta es la versión post-print del siguiente artículo: González-Rosende, ME., Castillo García, E., Jennings, WB. & Malone, JF. (2017). Stereodynamics and Edge-to-Face CH-π aromatic interactions in imino compounds containing heterocyclic rings. Organic & Biomolecular Chemistry, n. 6, que se ha publicado de forma definitiva en https://doi.org/10.1039/C6OB02618D

Possible reasons for the very low projected rotation velocity of BF Ori compared to other UX Ori stars are discussed. The hypothesis of a close companion that slows down the star’s rotation by a tidal interaction is examined. Based on a theory of synchronization and modern models of evolution, the interaction is calculated numerically for different masses of the companion and values of the semi-major axis. It is shown that in order to obtain the projected velocity observed for BF Ori, the companion must have a mass greater than 0.5M⨀ . Such a large companion should have been discovered observationally. It is suggested that the low rotation velocity of BF Ori is more likely to be related to the distribution of the angular momentum of a protostellar cloud between the angular momentum of the star and the orbital angular momentum of a low-mass companion.

Dahlander motors are using with different speed regulation needs. In this article, dynamic braking is using by injecting a DC voltage to see energy usage at fast and slow rotation. Control of the fast and slow rotation at the control panel using Arduino. The DC voltage variations given are 15 volts, 20 volts, and 24 volts. At a 15 volt DC voltage injection, the energy needed at fast rotation is 0.0018 Wh and at slow rotation 0.00072 Wh. For injection of a 20 volt DC voltage, the energy required for fast rotation at 0.0025 Wh and at 0.00085 Wh for slow rotation. Whereas 24 volt DC voltage injection, the energy needed at 0.0036 Wh for fast rotation and 0.00077 Wh for slow rotation.

Context. Teegarden's Star is the brightest and one of the nearest ultra-cool dwarfs in the solar neighbourhood. For its late spectral type (M7.0 V), the star shows relatively little activity and is a prime target for near-infrared radial velocity surveys such as CARMENES. Aims. As part of the CARMENES search for exoplanets around M dwarfs, we obtained more than 200 radial-velocity measurements of Teegarden's Star and analysed them for planetary signals. Methods. We find periodic variability in the radial velocities of Teegarden's Star. We also studied photometric measurements to rule out stellar brightness variations mimicking planetary signals. Results. We find evidence for two planet candidates, each with 1.1 M minimum mass, orbiting at periods of 4.91 and 11.4 d, respectively. No evidence for planetary transits could be found in archival and follow-up photometry. Small photometric variability is suggestive of slow rotation and old age. Conclusions. The two planets are among the lowest-mass planets discovered so far, and they are the first Earth-mass planets around an ultra-cool dwarf for which the masses have been determined using radial velocities.© ESO 2019., M.Z. acknowledges support from the Deutsche Forschungsgemeinschaft under DFG RE 1664/12-1 and Research Unit FOR2544 >Blue Planets around Red Stars>, project no. RE 1664/14-1. CARMENES is an instrument for the Centro Astronomico Hispano-Aleman de Calar Alto (CAHA, Almeria, Spain). CARMENES is funded by the German Max-Planck-Gesellschaft (MPG), the Spanish Consejo Superior de Investigaciones Cientificas (CSIC), the European Union through FEDER/ERF FICTS-2011-02 funds, and the members of the CARMENES Consortium (Max-Planck-Institut fur Astronomie, Instituto de Astrofisica de Andalucia, Landessternwarte Konigstuhl, Institut de Ciencies de l'Espai, Institut fur Astrophysik Gottingen, Universidad Complutense de Madrid, Thuringer Landessternwarte Tautenburg, Instituto de Astrofisica de Canarias, Hamburger Sternwarte, Centro de Astrobiologia and Centro Astronomico Hispano-Aleman), with additional contributions by the Spanish Ministry of Economy, the German Science Foundation through the Major Research Instrumentation Programme and DFG Research Unit FOR2544 >Blue Planets around Red Stars>, the Klaus Tschira Stiftung, the states of Baden-Wurttemberg and Niedersachsen, and by the Junta de Andalucia. Based on data from the CARMENES data archive at CAB (INTA-CSIC). This article is based on observations made with the MuSCAT2 instrument, developed by ABC, at Telescopio Carlos Sanchez operated on the island of Tenerife by the IAC in the Spanish Observatorio del Teide. Data were partly collected with the 150-cm and 90-cm telescopes at the Sierra Nevada Observatory (SNO) operated by the Instituto de Astrofisica de Andalucia (IAA-CSIC). Data were partly obtained with the MONET/South telescope of the MOnitoring NEtwork of Telescopes, funded by the Alfried Krupp von Bohlen und Halbach Foundation, Essen, and operated by the Georg-August-Universitat Gottingen, the McDonald Observatory of the University of Texas at Austin, and the South African Astronomical Observatory. We acknowledge financial support from the Spanish Agencia Estatal de Investigacion of the Ministerio de Ciencia, Innovacion y Universidades and the European FEDER/ERF funds through projects AYA2015-69350-C3-2-P, AYA2016-79425-C3-1/2/3-P, AYA2018-84089, BES-2017-080769, BES-2017-082610, ESP2015-65712-C5-5-R, ESP2016-80435-C2-1/2-R, ESP2017-87143-R, ESP2017-87676-2-2, ESP2017-87676-C5-1/2/5-R, FPU15/01476, RYC-2012-09913, the Centre of Excellence >Severo Ochoa> and >Maria de Maeztu> awards to the Instituto de Astrofisica de Canarias (SEV-2015-0548), Instituto de Astrofisica de Andalucia (SEV-2017-0709), and Centro de Astrobiologia (MDM-2017-0737), the Generalitat de Catalunya through CERCA programme>, the Deutsches Zentrum fur Luft-und Raumfahrt through grants 50OW0204 and 50OO1501, the European Research Council through grant 6 94 513, the Italian Ministero dell'instruzione, dell'universita de della ricerca and Universita degli Studi di Roma Tor Vergata through FFABR 2017 and >Mission: Sustainability 2016>, the UK Science and Technology Facilities Council through grant ST/P000592/1, the Israel Science Foundation through grant 848/16, the Chilean CONICYT-FONDECYT through grant 31 80 405, the Mexican CONACYT through grant CVU 4 48 248, the JSPS KAKENHI through grants JP18H01265 and 18H05439, and the JST PRESTO through grant JPMJPR1775.

The problem of the correlation of the global dynamic phenomenon “Chandler wobble” with the local dynamics in different parts of the Earth’s crust and lithosphere is wide of the solution. In this study, an attempt was made to approach the solution by analyzing the temporal variations of local seismic activity in the restricted geospace volumes (GSV) within the uniform seismoactive regions. The driver of Chandler wobble is the deep mantle – the most hard and most massive Earth’s layer, whose large inertia tensor value is able to keep up Chandler’s specific rotation of the Earth for a long time. We use the geocentric coordinate system where daily rotation is absent. In this system Chandler wobble is very slow rotation of the Earth around the current equatorial axis (the pole of which is denoted as EP14). Probably, this slow rotation can influence on the seismic events in the GSV. This influence is proposed to determine by the some statistical parameter EP14gsv that indicates the most typical position EP14 on equator when the most part of the earthquakes have occurred in the given GSV. For some geospace volumes the distribution indicates certain longitudes, where the number of seismic events is maximal or minimal.

The development of a platform to mix active imaging sensors into an Augmented Reality Environment. The system makes use of a 2D LiDAR modified into a 3D LiDAR on a mesh network. The 2D LiDAR, alongside a custom designed mount gives the ability to provide a slow rotation rate 3D LiDAR scan of the environment in conjunction with 3D active imaging and sensors. The data can then interpreted by the Unity game engine to be used in applications with multiperspective features in Augmented Reality. The goal of this work is to explore this collected data and apply it to immersive technology applications developed as means towards ongoing open source development.

Since its discovery more than half a century ago Przybylski's star (HD101065) continues to excite the astronomical community by the unusual nature of its spectrum, exhibiting exotic element abundances. This star was also the first magnetic chemically peculiar A-type star for which the presence of rapid oscillations was established. Our analysis of newly acquired and historic longitudinal magnetic field measurements indicates that Przybylski's star is also unusual with respect to its extremely slow rotation. Adopting a dipolar structure for the magnetic field and using a sine wave fit to all reported longitudinal magnetic field values over the last 43yr, we find a probable rotation period P_rot ~ 188yr, which however has to be considered tentative as it does not represent a unique solution and has to be verified by future observations. Additionally, based on our own spectropolarimetric material obtained with HARPSpol, we discuss the impact of the anomalous structure of its atmosphere, in particular of the non-uniform horizontal and vertical distributions of chemical elements on the magnetic field measurements and the pulsational variability. Anomalies related to the vertical abundance stratification of Pr and Nd are for the first time used to establish the presence of a radial magnetic field gradient., 11 pages, 4 tables, 7 figures, accepted for publication in MNRAS

A new rotation version of the Curzon-Chazy metric is found. This new metric was obtained by means of a perturbation method, in order to include slow rotation. The solution is then proved to fulfill the Einstein’s equations using a REDUCE program. Furthermore, the applications of this new solution are discussed. Se encontró una nueva versión rotante de la métrica de Curzon-Chazy. Esta nueva métrica fue obtenida por medio de un método perturbativo para incluir rotación lenta. Se prueba que la métrica obtenida es solución a las ecuaciones de Einstein por medio de un programa en REDUCE. Finalmente, se discuten las aplicaciones de esta nueva solución.

Intensive rotational grazing systems (also called cell grazing, holistic grazing or time-controlled grazing) are often implemented to improve production and environmental outcomes. Over recent years there has been considerable interpretation and adaption of the holistic principles that guide the management of these systems. In southern Australia, this has led to an increasing use of longer rest periods for intensive rotational grazing. This experiment was established to compare three intensive rotational grazing strategies (fast rotation [FR], average 57-day rest; slow rotation [SR], average 114-day rest; and flexible grazing [FX], based on availability of green herbage mass) with continuous grazing (CG) to assess the impact these systems have on vegetation and diet quality. The grazing treatments were run across three production zones (PZs) in the landscape (low [LPZ], medium [MPZ] and high [HPZ]) to determine whether management by landscape interactions influenced vegetation. Pasture composition was mostly influenced by PZ in the landscape with Microlaena stipoides and Holcus lanatus more prevalent in the HPZ and Rytidosperma spp. more common in the LPZ. The intensive rotational grazing treatments all had greater herbage mass and ground cover than CG. Composition change often occurred in one PZ and not another (e.g. Hypochaeris radicata increased with SR in the LPZ), or there were contrasting effects in different parts of the landscape (e.g. M. stipoides increased with FR compared with CG in the HPZ but decreased in the LPZ). Diet quality was lower for the SR compared with the other grazing treatments. Maintaining a post-grazing benchmark of >0.5 t green DM ha−1 was associated with a higher diet quality. Based on this two-and-a-half-year study run during poor seasons, it can be concluded that intensive rotational grazing can be managed, with fast and flexible rotations, to achieve per head animal performance similar to CG, but with higher herbage mass, ground cover and a desirable pasture composition.Keywords: ground cover, holistic grazing, landscape variability, native pasture, pasture composition change