405 research outputs found

    Phase transitions for suspension flows

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    This paper is devoted to study thermodynamic formalism for suspension flows defined over countable alphabets. We are mostly interested in the regularity properties of the pressure function. We establish conditions for the pressure function to be real analytic or to exhibit a phase transition. We also construct an example of a potential for which the pressure has countably many phase transitions.Comment: Example 5.2 expanded. Typos corrected. Section 6.1 superced the note "Thermodynamic formalism for the positive geodesic flow on the modular surface" arXiv:1009.462

    Homeomorphic Embedding for Online Termination of Symbolic Methods

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    Well-quasi orders in general, and homeomorphic embedding in particular, have gained popularity to ensure the termination of techniques for program analysis, specialisation, transformation, and verification. In this paper we survey and discuss this use of homeomorphic embedding and clarify the advantages of such an approach over one using well-founded orders. We also discuss various extensions of the homeomorphic embedding relation. We conclude with a study of homeomorphic embedding in the context of metaprogramming, presenting some new (positive and negative) results and open problems

    The non-convex shape of (234) Barbara, the first Barbarian

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    Asteroid (234) Barbara is the prototype of a category of asteroids that has been shown to be extremely rich in refractory inclusions, the oldest material ever found in the Solar System. It exhibits several peculiar features, most notably its polarimetric behavior. In recent years other objects sharing the same property (collectively known as "Barbarians") have been discovered. Interferometric observations in the mid-infrared with the ESO VLTI suggested that (234) Barbara might have a bi-lobated shape or even a large companion satellite. We use a large set of 57 optical lightcurves acquired between 1979 and 2014, together with the timings of two stellar occultations in 2009, to determine the rotation period, spin-vector coordinates, and 3-D shape of (234) Barbara, using two different shape reconstruction algorithms. By using the lightcurves combined to the results obtained from stellar occultations, we are able to show that the shape of (234) Barbara exhibits large concave areas. Possible links of the shape to the polarimetric properties and the object evolution are discussed. We also show that VLTI data can be modeled without the presence of a satellite.Comment: 10 pages, 6 figure

    (16) Psyche: A mesosiderite-like asteroid?

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    Asteroid (16) Psyche is the target of the NASA Psyche mission. It is considered one of the few main-belt bodies that could be an exposed proto-planetary metallic core and that would thus be related to iron meteorites. Such an association is however challenged by both its near- and mid-infrared spectral properties and the reported estimates of its density. Here, we aim to refine the density of (16) Psyche to set further constraints on its bulk composition and determine its potential meteoritic analog. We observed (16) Psyche with ESO VLT/SPHERE/ZIMPOL as part of our large program (ID 199.C-0074). We used the high angular resolution of these observations to refine Psyche's three-dimensional (3D) shape model and subsequently its density when combined with the most recent mass estimates. In addition, we searched for potential companions around the asteroid. We derived a bulk density of 3.99\,±\pm\,0.26\,g\cdotcm3^{-3} for Psyche. While such density is incompatible at the 3-sigma level with any iron meteorites (\sim7.8\,g\cdotcm3^{-3}), it appears fully consistent with that of stony-iron meteorites such as mesosiderites (density \sim4.25\,\cdotcm3^{-3}). In addition, we found no satellite in our images and set an upper limit on the diameter of any non-detected satellite of 1460\,±\pm\,200}\,m at 150\,km from Psyche (0.2\%\,×\times\,RHill_{Hill}, the Hill radius) and 800\,±\pm\,200\,m at 2,000\,km (3\%\,×\times\,RHillR_{Hill}). Considering that the visible and near-infrared spectral properties of mesosiderites are similar to those of Psyche, there is merit to a long-published initial hypothesis that Psyche could be a plausible candidate parent body for mesosiderites.Comment: 16 page

    Pengaruh pemberian hukuman terhadap pembentukan akhlaq peserta didik di SMP Muhammadiyah 1 Sidoarjo

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    Peserta didik yang nakal disekolah hanya dianggap sebagai pengisi waktu saja dari pada kesepian di rumah tidak ada teman. Peserta didik yang berpendapat demikian akan menjadi penghalang terhadap kemajuan belajar dirinya sendiri mapun teman-temannya. Akibatnya mereka yang melanggar peraturan di sekolah dan mendapat hukuman atau sanksi. Hukuman sendiri di sekolah dibuat bukan sebagai pembalasan, tetapi dibuat untuk memperbaiki peserta didik yang dihukum dan melindungi pesera didik lain dari kesalahan yang sama. Oleh karenanya diperlukan pendidikan yang baik untuk membentuk akhlak siswa, diantaranya melalui penerapan dari hukuman sebagai alat pendidikan agar terdapat efek jera. Penelitian ini dilatar belakangi karena akhlak adalah kunci utama untuk menjadi insan kamil. Permasalahan dalam penelitian ini adalah (1) Bagaimana pemberian Hukuman di SMP Muhammadiyah 1 Sidoarjo? (2) Bagaimana pembentukan Akhlak peserta didik di SMP Muhammadiyah 1 Sidoarjo? (3) Bagaimana pengaruh Pemberian Hukuman terhadap Pembentukan Akhlaq peserta didik di SMP Muhammadiyah 1 Sidoarjo? Instrument pengumpulan data dalam penelitian ini menggunakan teknik observasi. Kuesioner dan Interview sebagai instrumen pengumpulan data primer dan teknik dokumentasi sebagai instrument pengumpulan data sekunder. Sedangkan analisis data menggunakan teknik prosentase untuk data yang bersifat deskriptif dan teknik Regresi Linier untuk data yang bersifat kuantitatif. Hasil penelitian menunjukkan bahwa (1) Pemberian hukuman di SMP Muhammadiyah 1 Sidoarjo tergolong baik. (2) Pembentukan akhlak peserta didik di SMP Muhammadiyah 1 Sidoarjo tergolong baik. (3) Hasil perhitungan Regresi Linier diperoleh angka yang nilainya tersebut menunjukkan lebih besar dari Harga Kritik Regresi Linier baik pada taraf signifikansi 5 % maupun 1 %, berarti hipotesis alternatif (Ha) diterima, dan hipotesis nihil (Ho) ditolak. Kesimpulan bahwa terdapat pengaruh antara variabel Pemberian hukuman terhadap pembentukan akhlak peserta didik di SMP Muhammadiyah 1 Sidoarjo sebesar 5,7 %

    Thermoreflectance of V, Nb, and paramagnetic Cr

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    Thermoreflectance measurements of V, Nb, and Cr films were performed near 80 and 340 K to investigate the electronic properties of these metals. The thermoreflectance spectra ΔRR were Kramers-Kronig analyzed to determine the temperature dependence of the dielectric functions. The results were compared with previous derivative measurements of Mo and with static measurements of the optical reflectance of the bcc metals. Interpretation of the structures was guided by recent band calculations. It was shown that the observed features reflect the behavior of large volumes of the Brillouin zone rather than well-defined singularities.This article is from Physical Review B 14 (1976): 459, doi:10.1103/PhysRevB.14.459. Posted with permission.</p

    Prenatal Activation of Microglia Induces Delayed Impairment of Glutamatergic Synaptic Function

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    BACKGROUND: Epidemiological studies have linked maternal infection during pregnancy to later development of neuropsychiatric disorders in the offspring. In mice, experimental inflammation during embryonic development impairs behavioral and cognitive performances in adulthood. Synaptic dysfunctions may be at the origin of cognitive impairments, however the link between prenatal inflammation and synaptic defects remains to be established. METHODOLOGY/PRINCIPAL FINDINGS: In this study, we show that prenatal alteration of microglial function, including inflammation, induces delayed synaptic dysfunction in the adult. DAP12 is a microglial signaling protein expressed around birth, mutations of which in the human induces the Nasu-Hakola disease, characterized by early dementia. We presently report that synaptic excitatory currents in mice bearing a loss-of-function mutation in the DAP12 gene (DAP12(KI) mice) display enhanced relative contribution of AMPA. Furthermore, neurons from DAP12(KI) P0 pups cultured without microglia develop similar synaptic alterations, suggesting that a prenatal dysfunction of microglia may impact synaptic function in the adult. As we observed that DAP12(KI) microglia overexpress genes for IL1beta, IL6 and NOS2, which are inflammatory proteins, we analyzed the impact of a pharmacologically-induced prenatal inflammation on synaptic function. Maternal injection of lipopolysaccharides induced activation of microglia at birth and alteration of glutamatergic synapses in the adult offspring. Finally, neurons cultured from neonates born to inflamed mothers and cultured without microglia also displayed altered neuronal activity. CONCLUSION/SIGNIFICANCE: Our results demonstrate that prenatal inflammation is sufficient to induce synaptic alterations with delay. We propose that these alterations triggered by prenatal activation of microglia provide a cellular basis for the neuropsychiatric defects induced by prenatal inflammation

    Inhibitory control, but not prolonged object-related experience appears to affect physical problem-solving performance of pet dogs

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    Human infants develop an understanding of their physical environment through playful interactions with objects. Similar processes may influence also the performance of non-human animals in physical problem-solving tasks, but to date there is little empirical data to evaluate this hypothesis. In addition or alternatively to prior experiences, inhibitory control has been suggested as a factor underlying the considerable individual differences in performance reported for many species. Here we report a study in which we manipulated the extent of object-related experience for a cohort of dogs (Canis familiaris) of the breed Border Collie over a period of 18 months, and assessed their level of inhibitory control, prior to testing them in a series of four physical problem-solving tasks. We found no evidence that differences in object-related experience explain variability in performance in these tasks. It thus appears that dogs do not transfer knowledge about physical rules from one physical problem-solving task to another, but rather approach each task as a novel problem. Our results, however, suggest that individual performance in these tasks is influenced in a complex way by the subject’s level of inhibitory control. Depending on the task, inhibitory control had a positive or a negative effect on performance and different aspects of inhibitory control turned out to be the best predictors of individual performance in the different tasks. Therefore, studying the interplay between inhibitory control and problem-solving performance will make an important contribution to our understanding of individual and species differences in physical problem-solving performance
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