196 research outputs found
Mid-infrared laser light nulling experiment using single-mode conductive waveguides
Aims: In the context of space interferometry missions devoted to the search
of exo-Earths, this paper investigates the capabilities of new single mode
conductive waveguides at providing modal filtering in an infrared and
monochromatic nulling experiment; Methods: A Michelson laser interferometer
with a co-axial beam combination scheme at 10.6 microns is used. After
introducing a Pi phase shift using a translating mirror, dynamic and static
measurements of the nulling ratio are performed in the two cases where modal
filtering is implemented and suppressed. No additional active control of the
wavefront errors is involved. Results: We achieve on average a statistical
nulling ratio of 2.5e-4 with a 1-sigma upper limit of 6e-4, while a best null
of 5.6e-5 is obtained in static mode. At the moment, the impact of external
vibrations limits our ability to maintain the null to 10 to 20 seconds.;
Conclusions: A positive effect of SM conductive waveguide on modal filtering
has been observed in this study. Further improvement of the null should be
possible with proper mechanical isolation of the setup.Comment: Accepted in A&A, 7 pages, 5 figure
Nitrogen flow analysis in Spain: Perspectives to increase sustainability
Nitrogen (N) is a macronutrient that, together with P and K, is vital for improving agricultural yields, but its excessive use in crop fertilisation and presence in treated wastewater and sludge are generating emissions both into the atmosphere and into natural water bodies, which leads to eutrophication events. The Haber–Bosch process is energy-intensive and it is the main chemical route to produce reactive nitrogen for the production of fertilisers. Furthermore, there is a strong dependence on imports of reactive nitrogen in Spain and Europe. For these reasons, it is necessary to propose sustainable alternatives that allow solving environmental and supply problems, in addition to proposing efficient management schemes that fit into the circular economy approach. In this context, a nitrogen flow analysis (NFA) was carried out for Spain with the year 2016 as reference. To assess some interactions and flows of N, specific sub-models were also considered for the agriculture and waste management systems. For the food and non-food flow systems, country-specific data were considered. The sectors covered were crop production (CP), animal production (AP), food processing (FP), non-food production (NF) and human consumption (HC). The results reveal a total annual import of 2142 kt N/y, of which 43 % accumulated in stocks of soils and water bodies (913 kt N/y). The largest proportion of losses was associated with emissions from agriculture (724 kt N/y to water bodies and 132 kt N/y accumulated in soils), followed by industry emissions to the atmosphere (122 kt N/y). Wastewater treatment plants (WWTPs) received around 67 kt N/y, of which 26 % was removed as biosolids and 20 % of these biosolids were recovered to be used for fertilising applications. The 49 kt N/y discharged in the final treated effluent represented 79 % of the total loss of reactive nitrogen to water bodies. In addition, an analysis of N-use efficiency and the actions required for its improvement in Spain, as well as the impact of the current diet on the N cycle, was carried out.Peer ReviewedPostprint (author's final draft
Theortetical Models of Extrasolar Giant Planets
The recent discoveries of giant planets around nearby stars have galvanized
the planetary science community, astronomers, and the public at large. Since
{\it direct} detection is now feasible, and is suggested by the recent
acquisition of Gl229 B, it is crucial for the future of extrasolar planet
searches that the fluxes, evolution, and physical structure of objects from
Saturn's mass to 15 Juipter masses be theoretically investigated. We discuss
our first attempts to explore the characteristics of extrasolar giant planets
(EGPs), in aid of both NASA's and ESA's recent plans to search for such planets
around nearby stars.Comment: LaTeX, using espcrc2.sty style files from Elsevier, 10 pages, 4
figures, to be published in the Proceedings of the International Conference
on "Sources and Detection of Dark Matter in the Universe," ed. by D. Sanders
et al. (Nuclear Physics B Supplement), 199
GAUCÍN (Málaga). Castillo de Gaucín. 1:980
Manuscrito firmado y rubricado por el autor. A plumilla en tinta negra y carmín y coloreado a la acuarela en siena y carmín.Indica el núcleo de población.Relación de las principales dependencias del castillo indicada por clave numérica.Se dispone además de reproducción fotográfica en negativo sobre papel
RONDA (Málaga) (Partido judicial). Caminos (1811?). 1:20.000
Manuscrito firmado y rubricado por el autor. A plumilla en tintas negra y carmín y coloreado a la acuarela en azul y carmínRelieve representado por sombreadoRelación de los principales accidentes geográficos, castillo, huertas y cañadas y núcleo de población indicada por clave numéricaSe dispone además de reproducción fotográfica en negativo sobre pape
HOSTALRICH (Gerona). Asedios. 1823 (1810). 1:10.000
Comprende los términos municipales de Hostalrich, San Felíu Busalleu y Massanas, en la provincia de LéridaFecha tomada del catálogo del SGE: "Cataluña. Provincia de Gerona. Siglos XVII a XIX". 1970, p. 610Manuscrito firmado y rubricado por el autor. A plumilla en tinta negra y coloreado a la acuarela en azul, carmín y sienaRelieve representado a trazosIndica el rodeo que hicieron los franceses (por Massanes), para evitar el castillo de Hostalrich en diciembre de 1808Relación de las poblaciones y accidentes geográficos más importantes indicada por clave numéric
Modal Filtering for Nulling Interferometry-First Single-Mode Conductive Waveguides in the Mid-Infrared
This paper presents the work achieved for the manufacturing and
characterization of first single-mode waveguides to be used as modal filters
for nulling interferometry in the mid-infrared range [4-20 um]. As very high
dynamic range is mandatory for detection of Earth-like planets, modal filtering
is one of the most stringent instrumental aspects. The hollow metallic
waveguides (HMW) presented here are manufactured using micro-machining
techniques. Single-mode behavior has been investigated in laboratory through a
technique of polarization analysis while transmission features have been
measured using flux relative comparison. The single-mode behavior have been
assessed at lambda=10.6 um for rectangular waveguides with dimensions a=10 um
and b<5.3 um with an accuracy of ~2.5 %. The tests have shown that a
single-polarization state can be maintained in the waveguide. A comparison with
results on multi-mode HMW is proposed. Excess losses of 2.4 dB (~ 58 %
transmission) have been measured for a single-mode waveguide. In particular,
the importance of coupling conditions into the waveguide is emphasized here.
The goal of manufacturing and characterizing the first single-mode HMW for the
mid-infrared has been achieved. This opens the road to the use of integrated
optics for interferometry in the mentioned spectral range.Comment: 10 pages, 6 figures, accepted in A&
The effectiveness evaluation of a multimedia hepatitis C prevention program for Hispanic HIV-infected individuals
Introduction—With the introduction of highly active antiretroviral therapy the Hepatitis C virus
(HCV) infection has became a primary health problem among individuals suffering from HIV/
AIDS in Puerto Rico, principally those who are injecting drug users (IDUs). A multimedia
educational intervention, based on the Health Beliefs Model and Social Cognitive Theory was
developed and implemented to reduce HCV associated risk behaviors among IDUs.
Methods—A pre- and post- intervention study evaluated the knowledge and behavioral changes
in a group of HIV-infected persons recruited from February 2006 through December 2008.
Results—A total of 110 participants were recruited; all were IDUs; 82% were men; 86.3% were
HIV/HCV co-infected and 24.5% had active injected drugs in the last month (prior to
recruitment). The group mean age was 42.2 ± 9.2 years and mean educational level was 10th
grade. Knowledge of HCV risk behaviors, perception of HCV susceptibility, and perception of
disease severity increased after the intervention. Knowledge of HCV clinical manifestations and
HIV co-infection complications and treatment also improved. In addition, HCV risk behaviors and
injecting drug practice decrease significantly among IDUs.
Conclusions—This new multimedia intervention captured and maintained the participants'
attention and interest, in that way facilitating their educational process. Thus, a greater of attention
and interest leads to greater knowledge and prevention improvement
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