382 research outputs found

    Salisapiliaceae – a new family of oomycetes from marsh grass litter of southeastern North America

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    Several filamentous oomycete species of the genus Halophytophthora have recently been described from marine environments, mostly from subtropical and tropical ecosystems. During a survey of oomycetes from leaf litter of Spartina alterniflora in salt marshes of southeastern Georgia, isolates of four taxa were recovered that bore similarity to some members of Halophytophthora but were highly divergent from isolates of Halophytophthora s.str. based on a combined sequence analysis of two nuclear loci. In phylogenetic analyses, these isolates were placed basal to a monophyletic group comprised of Pythium of the Pythiaceae and the Peronosporaceae. Sequence and morphology of these taxa diverged from the type species Halophytophthora vesicula, which was placed within the Peronosporaceae with maximum support. As a consequence a new family, the Salisapiliaceae, and a new genus, Salisapilia, are described to accommodate the newly discovered species, along with one species previously classified within Halophytophthora. Morphological features that separate these taxa from Halophytophthora are a smaller hyphal diameter, oospore production, lack of vesicle formation during sporulation, and a plug of hyaline material at the sporangial apex that is displaced during zoospore release. Our findings offer a first glance at the presumably much higher diversity of oomycetes in estuarine environments, of which ecological significance requires further exploration

    Biologically active Phytophthora mating hormone prepared by catalytic asymmetric total synthesis

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    A Phytophthora mating hormone with an array of 1,5-stereogenic centers has been synthesized by using our recently developed methodology of catalytic enantioselective conjugate addition of Grignard reagents. We applied this methodology in a diastereo- and enantioselective iterative route and obtained two of the 16 possible stereoisomers of Phytophthora hormone α1. These synthetic stereoisomers induced the formation of sexual spores (oospores) in A2 mating type strains of three heterothallic Phytophthora species, P. infestans, P. capsici, and P. nicotianae but not in A1 mating type strains. The response was concentration-dependent, and the oospores were viable. These results demonstrate that the biological activity of the synthetic hormone resembles that of the natural hormone α1. Mating hormones are essential components in the sexual life cycle of a variety of organisms. For plant pathogens like Phytophthora, sexual reproduction is important as a source of genetic variation. Moreover, the thick-walled oospores are the most durable propagules that can survive harsh environmental conditions. Sexual reproduction can thus greatly affect disease epidemics. The availability of synthetic compounds mimicking the activity of Phytophthora mating hormone will be instrumental for further unravelling sexual reproduction in this important group of plant pathogens.

    Measurement of the electric dipole moments for transitions to rubidium Rydberg states via Autler-Townes splitting

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    We present the direct measurements of electric-dipole moments for 5P3/2nD5/25P_{3/2}\to nD_{5/2} transitions with 20<n<4820<n<48 for Rubidium atoms. The measurements were performed in an ultracold sample via observation of the Autler-Townes splitting in a three-level ladder scheme, commonly used for 2-photon excitation of Rydberg states. To the best of our knowledge, this is the first systematic measurement of the electric dipole moments for transitions from low excited states of rubidium to Rydberg states. Due to its simplicity and versatility, this method can be easily extended to other transitions and other atomic species with little constraints. Good agreement of the experimental results with theory proves the reliability of the measurement method.Comment: 12 pages, 6 figures; figure 6 replaced with correct versio

    Electronic temperatures, densities and plasma X-ray emission of a 14.5 GHz Electron-Cyclotron Resonance Ion Source

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    We have performed a systematic study of the Bremsstrahlung emission from the electrons in the plasma of a commercial 14.5 GHz Electron-Cyclotron Resonance Ion Source. The electronic spectral temperature and the product of ionic and electronic densities of the plasma are measured by analyzing the Bremsstrahlung spectra recorded for several rare gases (Ar, Kr, Xe) as a function of the injected power. Within our uncertainty, we find an average temperature of ? 48 keV above 100W, with a weak dependency on the injected power and gas composition. Charge state distributions of extracted ion beams have been determined as well, providing a way to disentangle the ionic density from the electronic density. Moreover X-ray emission from highly charged argon ions in the plasma has been observed with a high-resolution mosaic crystal spectrometer, demonstrating the feasibility for high-precision measurements of transition energies of highly charged ions, in particular of the magnetic dipole (M1) transition of He-like of argon ions

    Observation of coherent many-body Rabi oscillations

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    A two-level quantum system coherently driven by a resonant electromagnetic field oscillates sinusoidally between the two levels at frequency Ω\Omega which is proportional to the field amplitude [1]. This phenomenon, known as the Rabi oscillation, has been at the heart of atomic, molecular and optical physics since the seminal work of its namesake and coauthors [2]. Notably, Rabi oscillations in isolated single atoms or dilute gases form the basis for metrological applications such as atomic clocks and precision measurements of physical constants [3]. Both inhomogeneous distribution of coupling strength to the field and interactions between individual atoms reduce the visibility of the oscillation and may even suppress it completely. A remarkable transformation takes place in the limit where only a single excitation can be present in the sample due to either initial conditions or atomic interactions: there arises a collective, many-body Rabi oscillation at a frequency N0.5ΩN^0.5\Omega involving all N >> 1 atoms in the sample [4]. This is true even for inhomogeneous atom-field coupling distributions, where single-atom Rabi oscillations may be invisible. When one of the two levels is a strongly interacting Rydberg level, many-body Rabi oscillations emerge as a consequence of the Rydberg excitation blockade. Lukin and coauthors outlined an approach to quantum information processing based on this effect [5]. Here we report initial observations of coherent many-body Rabi oscillations between the ground level and a Rydberg level using several hundred cold rubidium atoms. The strongly pronounced oscillations indicate a nearly complete excitation blockade of the entire mesoscopic ensemble by a single excited atom. The results pave the way towards quantum computation and simulation using ensembles of atoms

    PEMBERDAYAAN PEREMPUAN BERBASIS KREATIFITAS DI DUSUN MOJOREJO DESA JUNREJO KOTA BATU

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    Keadaan perekonomian saat ini sangat memprihatinkan khususnya di Indonesia yang terdapat berbagai permasalahan yang menyangkut mengenai kehidupan bermasyarakat, antara lain masalah kemiskinan, masalah pengangguran, masalah lingkungan hidup, dan lain-lain. Permasalahan tersebut timbul akibat semakin meningkatnya keadaan ekonomi yang tidak disesuaikan dengan kondisi masyarakat. Khususnya masyarakat menengah kebawah. Kemiskinan menjadi masalah yang penting saat ini di Indonesia, sehingga menjadi suatu fokus perhatian bagi pemerintah Indonesia. Masalah kemiskinan ini sangatlah kompleks karena berkaitan dengan aspek sosial, ekonomi, budaya, dan aspek lainnya. Kemiskinan terus menjadi masalah fenomenal di belahan dunia, khususnya Indonesia yang merupakan negara berkembang. Kemiskinan telah membuat jutaan anak tidak bisa mengenyam pendidikan, kesulitan membiayai kesehatan, kurangnya tabungan dan investasi, dan masalah lain yang menjurus ke arah tindakan kekerasan dan kejahatan. Kemisikinan menjadi salah satu fenomena masalah yang kerap kita temui di majalah, surat kabar, ataupun berita online lainnya. Dinas sosial Kota Batu setidaknya mencatat ada 2.339 keluarga miskin sedangkan badan pusat statistik menerangkan jumlah keluarga miskin mencapai 2.600 keluarga miskin. Ini cukup membuktikan untuk menjelaskan bahwa masih banyak keluarga Kota Batu yang masih harus berjuang hanya untuk sekedar membiayai anaknya masuk sekolah. Pemberdayaan menjadi salah satu alternatif untuk menyelesaikan masalah terkait dengan pengentasan kemiskinan. Dalam penelitian ini terkait dengan program pemberdayaan yang dilakukan oleh kelompok mahasiswa Universitas Muhammadiyah Malang dan didanai oleh DIKTI dari Program Kreatifitas Mahasiswa (PKM) yang mana saya termasuk dalam kelompok tersebut. Pengabdian masyarakat dalam bentuk pemberdayaan masyarakat ini mempunyai subyek pemberdayaan perempuan dusun Wonorejo Desa Junrejo Kota Batu. Proses pemberdayaan dilakukan selama tiga bulan di dusun setempat

    Phytophthora foliorum sp. nov., a new species causing leaf blight of azalea

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    a b s t r a c t A previously unknown Phytophthora was recovered more than 60 times from evergreen hybrid azalea leaves collected during surveys for the sudden oak death pathogen Phytophthora ramorum in California and Tennessee. The novel Phytophthora was discovered when genomic DNA from this species cross-reacted with the ITS-based diagnostic PCR primers used to screen plants for the presence of P. ramorum. This species had caducous, semi-papillate sporangia, was homothallic with both paragynous and amphigynous antheridia, and was pathogenic on both wounded and intact azalea leaves. Nuclear and mitochondrial sequence data indicate that this species is related to, but distinct from, P. ramorum. AFLP analysis indicates that the isolates of this species have limited genotypic diversity and share no markers with P. ramorum. This paper presents the formal description of P. foliorum as a new species and underscores the need for caution when relying solely on DNA-based diagnostic tools
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