HST survey of the Orion Nebula Cluster in the H2_2O 1.4 μ\mum absorption band: I. A census of substellar and planetary mass objects

In order to obtain a complete census of the stellar and sub-stellar population, down to a few M$_{Jup}$ in the $\sim1$ Myr old Orion Nebula Cluster, we used the infrared channel of the Wide Field Camera 3 of the Hubble Space Telescope with the F139M and F130N filters. These bandpasses correspond to the $1.4 \mu$m H$_2$O absorption feature and an adjacent line-free continuum region. Out of $4,504$ detected sources, $3,352$ (about $75\%$) appear fainter than m$_{130}=14$ (Vega mag) in the F130N filter, a brightness corresponding to the hydrogen-burning limit mass (M$\simeq 0.072 M_\odot$) at $\sim 1$ Myr. Of these, however, only $742$ sources have a negative F130M-139N color index, indicative of the presence of H$_2$O vapor in absorption, and can therefore be classified as bona-fide M and L dwarfs, with effective temperatures T$\lesssim 2850$ K at an assumed $1$ Myr cluster age. On our color-magnitude diagram, this population of sources with H$_2$O absorption appears clearly distinct from the larger background population of highly reddened stars and galaxies with positive F130M-F139N color index, and can be traced down to the sensitivity limit of our survey, m$_{130}\simeq 21.5$, corresponding to a $1$ Myr old $\simeq 3$M$_{Jup}$, planetary mass object under about 2 magnitudes of visual extinction. Theoretical models of the BT-Settl family predicting substellar isochrones of $1, 2$ and $3$ Myr (down to $\sim 1$M$_{Jup}$) fail to reproduce the observed H$_2$O color index at M$\lesssim 20$M$_{Jup}$. We perform a Bayesian analysis to determine extinction, mass and effective temperature of each sub-stellar member of our sample, together with its membership probability.Comment: Accepted for publication in the Astrophysical Journal. The resolution of several figures has been downgraded to comply with the size limit of arXiv submission

Determination of atrazine and intermediates of biodegradation in a liquid culture medium for the enrichment of the microbial consorcia

1-chloro-3-ethylamino-5-isopropylamino-2 ,4,6-triazine, is an herbicide used to control annual weeds and perennial grasses. Although this herbicide is banned in the European Union for its toxicity, it is still widely used. Also, its the second most frecuently employed in Uruguay. The main mechanism for removal of atrazine in neutral pH environments is the bacterial degradation. The microorganisms can mineralize atrazine giving ammonia and carbon dioxide or they can degrade it to intermediates which vary in persistence and toxicity. The separation and detection of atrazine intermediates is important to know the health risk that represents its partial degradation in the environment. Furthermore, the separation method could be usefull to characterize bacterial degraders with potential application in biorremediation. Among the atrazine biodegradation intermediates are the hidroxyatrazine, the desetylhidroxyatrazine, the desisopropylhidrtoxyatrazine and cyanuric acid. In this paper we developed a method to separate atrazine and metabolites in a synthetic culture medium used to select atrazine degrading bacteria. For this technique we optimized a high performance liquid chromatography (HPLC) ion pair method using an C8 column, mobile phase acetonitrile / water, gradient flow and an UV detector. We evaluated its application to detect intermediates in several bacterial enrichments. It was found that the method is suitable to distinguish different metabolic capabilities of these enrichment.La atrazina, 1-cloro-3-etilamino-5-isopropilamino-2,4,6-triazina, es un herbicida que se utiliza para el control de malezas anuales y gramíneas perennes. Aunque este herbicida se encuentra prohibido en la Unión Europea por su toxicidad y la de sus metabolitos, sigue siendo muy usado y en Uruguay ocupa el segundo lugar de importancia. El principal mecanismo de eliminación de la atrazina en ambientes con pH neutro es la degradación bacteriana. Los microorganismos pueden mineralizar la atrazina dando amonio y anhídrido carbónico o degradarla produciendo intermediarios de variada persistencia y toxicidad. La separación y detección de estos intermediarios es relevante para conocer el riesgo sanitario que representa su degradación parcial en el ambiente y para encontrar y caracterizar bacterias o consorcios degradadores con potencial aplicación en bioorremediación. Entre los intermediarios de la biodegradación de atrazina se encuentran la hidroxiatrazina, la desetilhidroxiatrazina, la desisopropilhidrtoxiatrazina y el ácido cianúrico. En el presente trabajo se desarrolló un método para separar atrazina de sus metabolitos en un medio de cultivo sintético empleado para seleccionar bacterias degradadoras de atrazina. Para esto se optimizó una técnica de cromatografía líquida de alta performance (HPLC) de par iónico utilizando una columna C8, fase móvil acetonitrilo/agua, con un gradiente de flujo y detector UV. Se evaluó su aplicación para detectar intermediarios en varios enriquecimientos bacterianos degradadores de atrazina. Se pudo comprobar que el método resulta adecuado para distinguir capacidades metabólicas de enriquecimientos diferentes.Asociación de Universidades Grupo Montevide

Determinación de atrazina e intermediarios de biodegradación en enriquecimientos bacterianos provenientes de cursos de agua superficial de Uruguay = Determination of atrazine and its biodegradation intermediates in bacterial enrichments obtained from Uruguayan water courses

La atrazina es un herbicida que se utiliza para el control de malezas anuales y gramíneas perennes. Aunque se encuentra prohibido en la Unión Europea por su toxicidad y la de sus metabolitos, en Uruguay ocupa el segundo lugar de importancia en volúmenes de importación. La presencia de atrazina ha sido especialmente relevante en algunos cursos de agua que surten a las plantas potabilizadoras nacionales. El principal mecanismo de eliminación de la atrazina en ambientes con pH neutro es la degradación bacteriana. Los microorganismos pueden degradar atrazina produciendo intermediarios de variada persistencia y toxicidad, o mineralizarla dando amonio y anhídrido carbónico. La separación y detección de estos intermediarios es importante para seleccionar consorcios bacterianos apropiados para aplicar en un proceso de biorremediación. En este trabajo se desarrolló un método isocrático de cromatografía líquida de alta performance (HPLC) usando un agente de par iónico y fase reversa para separar atrazina de algunos de sus metabolitos en un medio de cultivo sintético. Este método resultó adecuado para detectar los intermediarios de la degradación producidos por consorcios bacterianos autóctonos seleccionados. También se utilizó para determinar si un consorcio bacteriano activo podía degradar la atrazina adsorbida sobre carbón activado

Heavy Quark Symmetry Violation in Semileptonic Decays of D Mesons

The decays of $D$ mesons to $K l \nu$ and $K^* l \nu$ final states exhibit significant deviations from the predictions of heavy-quark symmetry, as one might expect since the strange quark's mass is of the same order as the QCD scale. Nonetheless, in order to understand where the most significant effects might lie for heavier systems (such as $B \to D l\nu$ and $B \to D^* l\nu$), the pattern of these deviations is analyzed from the standpoint of perturbative QCD and ${\cal O}(1/m_s)$ corrections. Two main effects are noted. First, the perturbative QCD corrections lead to an overall decrease of predicted rates, which can be understood in terms of production of excited kaonic states. Second, ${\cal O}(1/m_s)$ effects tend to cancel the perturbative QCD corrections in the case of $Kl\nu$ decay, while they have minimal effect in $K^*l\nu$ decay.Comment: 25 pages (LaTeX) + 7 pages of Postscript figures (included at end), EFI-92-3

HST Survey of the Orion Nebula Cluster in the H₂O 1.4 μm Absorption Band. I. A Census of Substellar and Planetary-mass Objects

In order to obtain a complete census of the stellar and substellar population, down to a few M_(Jup) in the ~1 Myr old Orion Nebula Cluster, we used the infrared channel of the Wide Field Camera 3 of the Hubble Space Telescope with the F139M and F130N filters. These bandpasses correspond to the 1.4 μm H₂O absorption feature and an adjacent line-free continuum region. Out of 4504 detected sources, 3352 (about 75%) appear fainter than m₁₃₀ = 14 (Vega mag) in the F130N filter, a brightness corresponding to the hydrogen-burning limit mass M ≃ 0.072 M_⊙) at ~1 Myr. Of these, however, only 742 sources have a negative F130M–F139N color index, indicative of the presence of H₂O vapor in absorption, and can therefore be classified as bona fide M and L dwarfs, with effective temperatures T ≾ 2850 K at an assumed 1 Myr cluster age. On our color–magnitude diagram (CMD), this population of sources with H₂O absorption appears clearly distinct from the larger background population of highly reddened stars and galaxies with positive F130M–F139N color index and can be traced down to the sensitivity limit of our survey, m₁₃₀ ≃ 21.5, corresponding to a 1 Myr old ≃ 3 M_(Jup) planetary-mass object under about 2 mag of visual extinction. Theoretical models of the BT-Settl family predicting substellar isochrones of 1, 2, and 3 Myr down to ~1 M_(Jup) fail to reproduce the observed H₂O color index at M ≾ 20 M_(Jup). We perform a Bayesian analysis to determine extinction, mass, and effective temperature of each substellar member of our sample, together with its membership probability

Taking a hard line with biotemplating: cobalt-doped magnetite magnetic nanoparticle arrays.

Rapid advancements made in technology, and the drive towards miniaturisation, means that we require reliable, sustainable and cost effective methods of manufacturing a wide range of nanomaterials. In this bioinspired study, we take advantage of millions of years of evolution, and adapt a biomineralisation protein for surface patterning of biotemplated magnetic nanoparticles (MNPs). We employ soft-lithographic micro-contact printing to pattern a recombinant version of the biomineralisation protein Mms6 (derived from the magnetotactic bacterium Magnetospirillum magneticum AMB-1). The Mms6 attaches to gold surfaces via a cysteine residue introduced into the N-terminal region. The surface bound protein biotemplates highly uniform MNPs of magnetite onto patterned surfaces during an aqueous mineralisation reaction (with a mean diameter of 90 ± 15 nm). The simple addition of 6% cobalt to the mineralisation reaction maintains the uniformity in grain size (with a mean diameter of 84 ± 14 nm), and results in the production of MNPs with a much higher coercivity (increased from ≈156 Oe to ≈377 Oe). Biotemplating magnetic nanoparticles on patterned surfaces could form a novel, environmentally friendly route for the production of bit-patterned media, potentially the next generation of ultra-high density magnetic data storage devices. This is a simple method to fine-tune the magnetic hardness of the surface biotemplated MNPs, and could easily be adapted to biotemplate a wide range of different nanomaterials on surfaces to create a range of biologically templated devices

The Long-Baseline Neutrino Experiment: Exploring Fundamental Symmetries of the Universe

The preponderance of matter over antimatter in the early Universe, the dynamics of the supernova bursts that produced the heavy elements necessary for life and whether protons eventually decay --- these mysteries at the forefront of particle physics and astrophysics are key to understanding the early evolution of our Universe, its current state and its eventual fate. The Long-Baseline Neutrino Experiment (LBNE) represents an extensively developed plan for a world-class experiment dedicated to addressing these questions. LBNE is conceived around three central components: (1) a new, high-intensity neutrino source generated from a megawatt-class proton accelerator at Fermi National Accelerator Laboratory, (2) a near neutrino detector just downstream of the source, and (3) a massive liquid argon time-projection chamber deployed as a far detector deep underground at the Sanford Underground Research Facility. This facility, located at the site of the former Homestake Mine in Lead, South Dakota, is approximately 1,300 km from the neutrino source at Fermilab -- a distance (baseline) that delivers optimal sensitivity to neutrino charge-parity symmetry violation and mass ordering effects. This ambitious yet cost-effective design incorporates scalability and flexibility and can accommodate a variety of upgrades and contributions. With its exceptional combination of experimental configuration, technical capabilities, and potential for transformative discoveries, LBNE promises to be a vital facility for the field of particle physics worldwide, providing physicists from around the globe with opportunities to collaborate in a twenty to thirty year program of exciting science. In this document we provide a comprehensive overview of LBNE's scientific objectives, its place in the landscape of neutrino physics worldwide, the technologies it will incorporate and the capabilities it will possess.Comment: Major update of previous version. This is the reference document for LBNE science program and current status. Chapters 1, 3, and 9 provide a comprehensive overview of LBNE's scientific objectives, its place in the landscape of neutrino physics worldwide, the technologies it will incorporate and the capabilities it will possess. 288 pages, 116 figure

ARMAZENAGEM REFRIGERADA DE PIMENTAS SOB CONDIÇÃO DE ATMOSFERA NORMAL E MODIFICADA

O cultivo de pimentas pode ser mais uma opção para os produtores diversificarem a produção e aumentarem sua renda. com este objetivo desenvolve-se pesquisas sobre o comportamento e adaptação das cultivares ‘Malagueta’, ‘Chapéu de Bispo’, ‘Cheiro de Luna’, ‘Jalapeño’ e ‘Novo México’ hà região e sua conservação armazenadas em frio em atmosfera normal e atmosfera modificada. O resultado esperado para este trabalho é o de a armazenagem em atmosfera modificada conservar o fruto por mais tempo em relação a armazenagem em atmosfera normal preservando as pimentas

Empathy among undergraduate medical students: A multi-centre cross-sectional comparison of students beginning and approaching the end of their course

BACKGROUND: Although a core element in patient care the trajectory of empathy during undergraduate medical education remains unclear. Empathy is generally regarded as comprising an affective capacity: the ability to be sensitive to and concerned for, another and a cognitive capacity: the ability to understand and appreciate the other person's perspective. The authors investigated whether final year undergraduate students recorded lower levels of empathy than their first year counterparts, and whether male and female students differed in this respect. METHODS: Between September 2013 and June 2014 an online questionnaire survey was administered to 15 UK, and 2 international medical schools. Participating schools provided both 5-6 year standard courses and 4 year accelerated graduate entry courses. The survey incorporated the Jefferson Scale of Empathy-Student Version (JSE-S) and Davis's Interpersonal Reactivity Index (IRI), both widely used to measure medical student empathy. Participation was voluntary. Chi squared tests were used to test for differences in biographical characteristics of student groups. Multiple linear regression analyses, in which predictor variables were year of course (first/final); sex; type of course and broad socio-economic group were used to compare empathy scores. RESULTS: Five medical schools (4 in the UK, 1 in New Zealand) achieved average response rates of 55 % (n = 652) among students starting their course and 48 % (n = 487) among final year students. These schools formed the High Response Rate Group. The remaining 12 medical schools recorded lower response rates of 24.0 % and 15.2 % among first and final year students respectively. These schools formed the Lower Response Rate Group. For both male and female students in both groups of schools no significant differences in any empathy scores were found between students starting and approaching the end of their course. Gender was found to significantly predict empathy scores, with females scoring higher than males. CONCLUSIONS: Participant male and female medical students approaching the end of their undergraduate education, did not record lower levels of empathy, compared to those at the beginning of their course. Questions remain concerning the trajectory of empathy after qualification and how best to support it through the pressures of starting out in medical practice