Ionization toward the high-mass star-forming region NGC 6334 I

Context. Ionization plays a central role in the gas-phase chemistry of molecular clouds. Since ions are coupled with magnetic fields, which can in turn counteract gravitational collapse, it is of paramount importance to measure their abundance in star-forming regions. Aims. We use spectral line observations of the high-mass star-forming region NGC 6334 I to derive the abundance of two of the most abundant molecular ions, HCO+ and N2H+, and consequently, the cosmic ray ionization rate. In addition, the line profiles provide information about the kinematics of this region. Methods. We present high-resolution spectral line observations conducted with the HIFI instrument on board the Herschel Space Observatory of the rotational transitions with Jup > 5 of the molecular species C17O, C18O, HCO+, H13CO+, and N2H+. Results. The HCO+ and N2H+ line profiles display a redshifted asymmetry consistent with a region of expanding gas. We identify two emission components in the spectra, each with a different excitation, associated with the envelope of NGC 6334 I. The physical parameters obtained for the envelope are in agreement with previous models of the radial structure of NGC 6334 I based on submillimeter continuum observations. Based on our new Herschel/HIFI observations, combined with the predictions from a chemical model, we derive a cosmic ray ionization rate that is an order of magnitude higher than the canonical value of 10^(-17) s-1. Conclusions. We find evidence of an expansion of the envelope surrounding the hot core of NGC 6334 I, which is mainly driven by thermal pressure from the hot ionized gas in the region. The ionization rate seems to be dominated by cosmic rays originating from outside the source, although X-ray emission from the NGC 6334 I core could contribute to the ionization in the inner part of the envelope.Comment: This paper contains a total of 10 figures and 3 table

Compact Q-balls and Q-shells in a scalar electrodynamics

We investigate spherically symmetric non topological solitons in electrodynamics with a scalar field self interaction U ~|\psi| taken from the complex signum-Gordon model. We find Q-balls for small absolute values of the total electric charge Q, and Q-shells when |Q| is large enough. In both cases the charge density exactly vanishes outside certain compact region in the three dimensional space. The dependence of the total energy E of small Q-balls on the total electric charge has the form E ~ |Q|^(5/6), while in the case of very large Q-shells E ~ |Q|^(7/6).Comment: 21 pages, 7 figure

Kandungan Bahan Aktif Dan Toksisitas Tumbuhan Hutan Asal Sulawesi Utara Yang Berpotensi Sebagai Obat

Pemanfaatan plasma nutfah sebagai sumber bahan obat merupakan bentuk kearifan tradisional yang diadopsi oleh masyarakat pada daerah tertentu dan identik dengan warisan turun-temurun. Makalah ini mendeskripsikan aspek etnobotani masyarakat Sulawesi Utara (Suku Minahasa, Mongondow dan Sangihe) dalam memanfaatkan sumberdaya alam hayati dari beberapa spesies tumbuhan hutan untuk pengobatan penyakit kanker secara tradisional, yang kemudian dibuktikan secara ilmiah melalu identifikasi kandungan bahan aktif dan toksisitasnya menggunakan metode Brine Shrimp Lethality Test (BSLT). Hasil penelitian menunjukkan bahwa masyarakat lokal Sulawesi Utara telah memanfaatkan bagian tertentu (seperti batang, kulit dan daun) dari 14 jenis tumbuhan hutan dalam pengobatan anti kanker dan penyakit lainnya. Ekstrak herbal dari kulit lawang (Cinnamomum cullilawan Bl) diidentifikasi mengandung senyawa alkaloid, sedangkan senyawa flavonoid terdeteksi pada ekstrak daun lingkube (Dischidia imbricata Steud) daun yantan (Blumea chinensis Dc), kulit ketapang (Terminalia catappa L), kulit kayu manumpang (Loranthus globulus Jacq), batang tanduk rusa, akar kayu gimto (Ligodyum sp.) akar rumput balsam ( Polygala paniculata L) dan akar cakar kucing (Acalypha indica L). Daun luhu (Crotalaria retusa L) dan kuhung-kuhung (Crotalaria striata Dc) mengandung senyawa steroid dan tanin. Sebanyak 9 dari 12 ekstrak n-butanol mampu memberikan efek toksik terhadap larva Artemia salina Leach yang ditandai melalui nilai LC50 kurang dari 1000 ppm. Nilai LC50 terkecil didapatkan dari ekstrak petroleum eter daun kuhung-kuhung (Crotalaria striata Dc) sebesar 68,33ppm dimana nilai ini mendekati standar efektifitas komponen bioaktif untuk melawan sel kanker berdasarkan kategori National Cancer Institute Amerika

Physical Adsorption at the Nanoscale: Towards Controllable Scaling of the Substrate-Adsorbate van der Waals Interaction

The Lifshitz-Zaremba-Kohn (LZK) theory is commonly considered as the correct large-distance limit for the van der Waals (vdW) interaction of adsorbates (atoms, molecules, or nanoparticles) with solid substrates. In the standard approximate form, implicitly based on "local" dielectric functions, the LZK approach predicts universal power laws for vdW interactions depending only on the dimensionality of the interacting objects. However, recent experimental findings are challenging the universality of this theoretical approach at finite distances of relevance for nanoscale assembly. Here, we present a combined analytical and numerical many-body study demonstrating that physical adsorption can be significantly enhanced at the nanoscale. Regardless of the band gap or the nature of the adsorbate specie, we find deviations from conventional LZK power laws that extend to separation distances of up to 10--20 nanometers. Comparison with recent experimental observation of ultra long-ranged vdW interactions in the delamination of graphene from a silicon substrate reveals qualitative agreement with the present theory. The sensitivity of vdW interactions to the substrate response and to the adsorbate characteristic excitation frequency also suggests that adsorption strength can be effectively tuned in experiments, paving the way to an improved control of physical adsorption at the nanoscale

Hydrogen Isocyanide in Comet 73P/Schwassmann-Wachmann (Fragment B)

We present a sensitive 3-sigma upper limit of 1.1% for the HNC/HCN abundance ratio in comet 73P/Schwassmann-Wachmann (Fragment B), obtained on May 10-11, 2006 using Caltech Submillimeter Observatory (CSO). This limit is a factor of ~7 lower than the values measured previously in moderately active comets at 1 AU from the Sun. Comet 73P/Schwassmann-Wachmann was depleted in most volatile species, except of HCN. The low HNC/HCN ratio thus argues against HNC production from polymers produced from HCN. However, thermal degradation of macromolecules, or polymers, produced from ammonia and carbon compounds, such as acetylene, methane, or ethane appears a plausible explanation for the observed variations of the HNC/HCN ratio in moderately active comets, including the very low ratio in comet 73P/Schwassmann-Wachmann reported here. Similar polymers have been invoked previously to explain anomalous 14N/15N ratios measured in cometary CN.Comment: 6 pages, 5 figures, 2 table

An updated transmission model for Salmonella in grower-finisher pigs

A model describing the transmission of Salmonella between pigs on a British continuous-production grower-finisher pig farm has previously beend eveloped. We will describe improvements to the model and updates to the parameter estimation