DNA Renaturation at the Water-Phenol Interface

We study DNA adsorption and renaturation in a water-phenol two-phase system, with or without shaking. In very dilute solutions, single-stranded DNA is adsorbed at the interface in a salt-dependent manner. At high salt concentrations the adsorption is irreversible. The adsorption of the single-stranded DNA is specific to phenol and relies on stacking and hydrogen bonding. We establish the interfacial nature of a DNA renaturation at a high salt concentration. In the absence of shaking, this reaction involves an efficient surface diffusion of the single-stranded DNA chains. In the presence of a vigorous shaking, the bimolecular rate of the reaction exceeds the Smoluchowski limit for a three-dimensional diffusion-controlled reaction. DNA renaturation in these conditions is known as the Phenol Emulsion Reassociation Technique or PERT. Our results establish the interfacial nature of PERT. A comparison of this interfacial reaction with other approaches shows that PERT is the most efficient technique and reveals similarities between PERT and the renaturation performed by single-stranded nucleic acid binding proteins. Our results lead to a better understanding of the partitioning of nucleic acids in two-phase systems, and should help design improved extraction procedures for damaged nucleic acids. We present arguments in favor of a role of phenol and water-phenol interface in prebiotic chemistry. The most efficient renaturation reactions (in the presence of condensing agents or with PERT) occur in heterogeneous systems. This reveals the limitations of homogeneous approaches to the biochemistry of nucleic acids. We propose a heterogeneous approach to overcome the limitations of the homogeneous viewpoint

Holomorphic self-maps of singular rational surfaces

We give a new proof of the classification of normal singular surface germs admitting non-invertible holomorphic self-maps and due to J. Wahl. We then draw an analogy between the birational classification of singular holomorphic foliations on surfaces, and the dynamics of holomorphic maps. Following this analogy, we introduce the notion of minimal holomorphic model for holomorphic maps. We give sufficient conditions which ensure the uniqueness of such a model.Comment: 37 pages. To appear in Publicacions Matematiques

Probing the Perturbative NLO Parton Evolution in the Small-xx Region

A dedicated test of the perturbative QCD NLO parton evolution in the very small-$x$ region is performed. We find a good agreement with recent precision HERA-data for $F_2^p(x,Q^2)$, as well as with the present determination of the curvature of $F_2^p$. Characteristically, perturbative QCD evolutions result in a positive curvature which increases as $x$ decreases. Future precision measurements in the very small $x$-region, $x<10^{-4}$, could provide a sensitive test of the range of validity of perturbative QCDComment: Revised version, to appear in EPJ

Transport of a quantum degenerate heteronuclear Bose-Fermi mixture in a harmonic trap

We report on the transport of mixed quantum degenerate gases of bosonic 87Rb and fermionic 40K in a harmonic potential provided by a modified QUIC trap. The samples are transported over a distance of 6 mm to the geometric center of the anti-Helmholtz coils of the QUIC trap. This transport mechanism was implemented by a small modification of the QUIC trap and is free of losses and heating. It allows all experiments using QUIC traps to use the highly homogeneous magnetic fields that can be created in the center of a QUIC trap and improves the optical access to the atoms, e.g., for experiments with optical lattices. This mechanism may be cascaded to cover even larger distances for applications with quantum degenerate samples.Comment: 7 pages, 8 figure

Observation of the TeV gamma-ray source MGRO J1908+06 with ARGO-YBJ

The extended gamma ray source MGRO J1908+06, discovered by the Milagro air shower detector in 2007, has been observed for about 4 years by the ARGO-YBJ experiment at TeV energies, with a statistical significance of 6.2 standard deviations. The peak of the signal is found at a position consistent with the pulsar PSR J1907+0602. Parametrizing the source shape with a two-dimensional Gauss function we estimate an extension \sigma = 0.49 \pm 0.22 degrees, consistent with a previous measurement by the Cherenkov Array H.E.S.S.. The observed energy spectrum is dN/dE = 6.1 \pm 1.4 \times 10^-13 (E/4 TeV)^{-2.54 \pm 0.36} photons cm^-2 s^-1 TeV^-1, in the energy range 1-20 TeV. The measured gamma ray flux is consistent with the results of the Milagro detector, but is 2-3 times larger than the flux previously derived by H.E.S.S. at energies of a few TeV. The continuity of the Milagro and ARGO-YBJ observations and the stable excess rate observed by ARGO-YBJ along 4 years of data taking support the identification of MGRO J1908+06 as the steady powerful TeV pulsar wind nebula of PSR J1907+0602, with an integrated luminosity above 1 TeV about 1.8 times the Crab Nebula luminosity.Comment: 6 pages, accepted for pubblication by ApJ. Replaced to correct the author lis

Masses and couplings of vector mesons from the pion electromagnetic, weak, and \pi\gamma transition form factors

We analyse the pion electromagnetic, charged-current, and $\pi\gamma$ transition form factors at timelike momentum transfers $q$, $q^2=s\le 1.4$ GeV$^2$, using a dispersion approach. We discuss in detail the propagator matrix of the photon-vector-meson system and define certain reduced amplitudes, or vertex functions, describing the coupling of this system to final states. We then apply the derived analytic expressions to the analysis of the recent $e^+e^-\to \pi^+\pi^-$, $\tau^-\to \pi^-\pi^0\nu_\tau$, and $e^+e^-\to \pi^0\gamma$ data. We find the reduced amplitudes for the coupling of the photon and vector mesons to two pseudoscalars to be constant, independent of $s$, in the range considered, indicating a "freezing" of the amplitudes for $s\le 1$ GeV. The fit to the form factor data leads to the following values of the Breit-Wigner resonance masses m_{\rho^-}=775.3\pm 0.8 MeV, m_{\rho^0}=773.7\pm 0.6 MeV and m_\omega=782.43\pm 0.05 MeV, where the errors are only statistical.Comment: revtex, 23 page

PEMBEL AJARAN ME MPRODUKSI TEKS ULASAN DRAMA MENGGUNAKAN METODE ASSESMENT SEARCH PADA SISWA KELA S XI SMA NEGERI 1 LEMBANG TAHUN PELAJARAN 2014/2015

vi ABSTRAK Pembelajaran Bahasa Indonesia di sekolah sangatlah penting bahkan menjadi salah satu persyaratan menghadapi Ujian Nasional. S alah satu keterampilan ya ng harus dikuasai adalah me nulis . Semua sisw a tentu memiliki poten si dalam menulis , termasuk me mproduksi teks ulasan berdasarkan struktur corak kritik apresiasi (segi positif) . Metode assessment search merupakan metode yang mengarahkan si swa pada keaktifan dan kerjasama . Untuk itu, penulis teratrik m elakukan penelitian dengan judul: “Pembel ajaran Me mproduksi Teks Ulasan Menggunakan Metode Assesment Search pada Siswa Kelas XI SMA Negeri 1 Kota Bandung Tahun Pelajaran 2014/2015. Permasalahan yang penulis rumuskan adalah; (1) . Mampukah penulis merencanakan, melaksanakan, dan mengevaluasi pembela - jaran memproduksi teks ulasan pada siswa SMAN 1 Lembang Bandung ? (2) Mampukah siswa SMAN 1 Lembang memproduksi teks ulasan drama berdasarkan struktur teksnya ? (3) Efektifkah metode assesment search digunakan dalam memproduksi teks ulasan . Hipotesis yan g penulis rumuskan adalah; ( 1 ). Penulis mampu melaksanakan pembelajaran menulis teks ulasan drama menggu nakan metode assesment search .( 2 ) . Siswa kelas XI SMA Negeri 1 Lembang mampu melaksanakan pembelajaran menulis teks ulasan drama menggu nakan metode asse sment search .( 3 ). Metode assesment search lebih efektif dan menyenangkan serta kreatif digunakan dalam pembelajaran menulis teks ulasan . Metode penelitian yang penulis gunakan adalah metode Quasi Eksperimental Design dengan teknik penelitian One - Group Pretest - Posttest Design . Adapun hasil penelitian; ( 1 ) Penulis mampu melaksanakan pembelajaran memproduksi teks ulasan drama dengan metode assessment search pada siswa kelas XI SMAN 1 Lembang. Hal ini didasari dari hasil penilaian persiapan dan pe laksanaan pembelajaran memproduksi teks ulasan drama dari guru mata pelajaran Bahasa dan Sastra Indonesia. Adapun hasil penilaian pelaksanaan pembelajaran penulis yaitu 3,8 dengan kategori nilai baik sekali (A). Kemudian, hasil penilaian Rencana Pelaksanaa n Pembelajaran (RPP) 3,9 dengan kategori baik sekali (A ). ( 2 ) Siswa kelas XI SMAN 1 Lembang mampu mengikuti pembelajaran memproduksi teks ulasan drama dengan menggunakan metode assessment search. Hal ini terbukti dari perolehan nilai rata - rata prates dan pa scates. Nilai rata - rata prates yaitu 17,0 sedangkan nilai rata - rata pascates adalah 68,6. Jadi, selisih antara nilai rata - rata prates dan pascates adalah 49,6. ( 3 ) Metode pembelajaran assessment search efektif diterapkan dalam pembelajaran memproduksi teks ulasan pada siswa kelas XI SMA Negeri 1 Lembang. Hal ini dapat dibuktikan dengan uji statistik thitung > ttabel yakni 4.6> 2,2 dalam tingkat kepercayaan 75% dengan taraf signifikan 25% dan derajat kebebasan 23. Artinya, penulis menyimpulkan bahwa semua hi potesis yang dirumuskan dapat diterima. Kata Kunci: Me mproduksi , Metode Assesment Search , Pembelajaran , Teks Ulasan

PA from an H5N1 highly pathogenic avian influenza virus activates viral transcription and replication and induces apoptosis and interferon expression at an early stage of infection

BACKGROUND: Although gene exchange is not likely to occur freely, reassortment between the H5N1 highly pathogenic avian influenza virus (HPAIV) and currently circulating human viruses is a serious concern. The PA polymerase subunit of H5N1 HPAIV was recently reported to activate the influenza replicon activity. METHODS: The replicon activities of PR8 and WSN strains (H1N1) of influenza containing PA from HPAIV A/Cambodia/P0322095/2005 (H5N1) and the activity of the chimeric RNA polymerase were analyzed. A reassortant WSN virus containing the H5N1 Cambodia PA (C-PA) was then reconstituted and its growth in cells and pathogenicity in mice examined. The interferon promoter, TUNEL, and caspase 3, 8, and 9 activities of C-PA-infected cells were compared with those of WSN-infected cells. RESULTS: The activity of the chimeric RNA polymerase was slightly higher than that of WSN, and C-PA replicated better than WSN in cells. However, the multi-step growth of C-PA and its pathogenicity in mice were lower than those of WSN. The interferon promoter, TUNEL, and caspase 3, 8, and 9 activities were strongly induced in early infection in C-PA-infected cells but not in WSN-infected cells. CONCLUSIONS: Apoptosis and interferon were strongly induced early in C-PA infection, which protected the uninfected cells from expansion of viral infection. In this case, these classical host-virus interactions contributed to the attenuation of this strongly replicating virus