472 research outputs found
Strong magnetic coupling of an ultracold gas to a superconducting waveguide cavity
Placing an ensemble of ultracold atoms in the near field of a
superconducting coplanar waveguide resonator (CPWR) with one can
achieve strong coupling between a single microwave photon in the CPWR and a
collective hyperfine qubit state in the ensemble with kHz larger than the cavity line width of
kHz. Integrated on an atomchip such a system constitutes a hybrid quantum
device, which also can be used to interconnect solid-state and atomic qubits,
to study and control atomic motion via the microwave field, observe microwave
super-radiance, build an integrated micro maser or even cool the resonator
field via the atoms
Aves y peces como bioindicadores de las alteraciones debidas al turismo en manantiales de zonas semiáridas en México: bases para la gestión
Tourist disturbance in semi–arid springs was analysed; birds and fish were selected as bioindicators. Media Luna spring is the biggest and most spatially complex system in the region, with the highest biodiversity levels and tourist use. Areas with the highest bird species richness and abundances showed highest structural heterogeneity and least direct human impact. No differences in species richness of fish were observed between sectors and the most abundant species were found in the sectors least perturbed by human activity. Factors that explained the bird distribution were the species´ tolerance to the effects of direct tourism (noise and direct presence of people) and habitat quality, mainly riparian vegetation. Aquatic vegetation condition was very important for fish. Six bird species and two fish species were relevant as indicators of the habitat quality related to human impact. Anthropic disturbance such as tree plantation favoured some bird species, whereas aquatic vegetation removal was favourable for some fish species, such as the endemic Cichlasoma bartoni, however, both types of disturbance were unfavourable for other species; riparian vegetation removal was negative for both groups. Controlled tourism promotes good conditions for C. bartoni establishment. Efficient conservation measures such as limiting touristic distribution are necessary for all species, especially for the fish community, in order to conserve biodiversity in general.
Key words: Wetlands, Species distribution, Threatened species, Endemism, Habitat loss, Spatial heterogeneity, Bioindicators.Para analizar las alteraciones por el turismo en manantiales de zonas semiáridas se utilizaron aves y peces como bioindicadores. Se seleccionó el manantial de la Media Luna por ser el más grande y complejo, y por incluir la más alta biodiversidad y el mayor impacto turístico en la zona. Los sectores con alta diversidad y abundancias de aves fueron los que tienen la mayor
heterogeneidad estructural y menor impacto humano directo. Las mayores abundancias de peces se encontraron en los sectores menos perturbados sin diferencias para la riqueza de especies. Los factores que explicaron la distribución de las aves fueron la tolerancia de las especies a los efectos directos del turismo (ruido y presencia directa de gente) y la calidad del hábitat, principalmente la vegetación ribereña. La condición de la vegetación acuática fue muy importante para los peces. Seis especies de aves y dos de peces fueron relevantes como indicadores de la calidad del hábitat en función del impacto humano. Las alteraciones antrópicas tales como la plantación de árboles favoreció a algunas especies de aves mientras que la eliminación de la vegetación acuática fue favorable para algunos peces como el endémico Cichlasoma bartoni, pero estas alteraciones fueron negativas para otras especies; la eliminación de la vegetación ribereña tuvo efectos negativos para ambos grupos. El turismo controlado crea condiciones favorables para C. bartoni. Para la conservación de la biodiversidad en general, se requieren medidas eficientes de conservación tales como la restricción geográfica del turismo especialmente importante para la comunidad de peces.
Palabras clave: Humedales, Distribución de las especies, Especies amenazadas, Endemismos, Pérdida de hábitat, Heterogeneidad espacial, Bioindicadores
Plant’s gypsum affinity shapes responses to specific edaphic constraints without limiting responses to other general constraints
Aims: Harsh edaphic environments harbor species with different soil affinities. Plant’s responses to specific edaphic constraints may be compromised against responses to prevalent stresses shared with other semi-arid environments. We expect that species with high edaphic affinity may show traits to overcome harsh soil properties, while species with low affinity may respond to environmental constraints shared with arid environments. Methods: We quantified the edaphic affinity of 12 plant species co-occurring in gypsum outcrops and measured traits related to plant responses to specific gypsum constraints (rooting and water uptake depth, foliar accumulation of Ca, S and Mg), and traits related to common constraints of arid environments (water use efficiency, macronutrients foliar content). Results: Plants in gypsum outcrops differed in their strategies to face edaphic limitations. A phylogenetic informed PCA segregated species based on their foliar Ca and S accumulation and greater water uptake depths, associated with plant responses to specific gypsum limitations. Species’ gypsum affinity explained this segregation, but traits related to water or nutrient use efficiency did not contribute substantially to this axis. Conclusions: Plant’s specializations to respond to specific edaphic constraints of gypsum soils do not limit their ability to deal with other non-specific environmental constraints
Empirical model for chlorophyll-a determination in inland waters from the forthcoming Sentinel-2 and 3. Validation from HICO images
Revista oficial de la Asociación Española de Teledetección[EN] Chlorophyll-a concentration is one of the main indicators of inland waters quality. Using CHRIS/PROBA images and in situ data obtained in four lakes in Colombia and Spain, we obtained empirical models for the estimation of chlorophyll-a concentration, which can be directly applied to future images of MSI Sentinel-2 and OLCI Sentinel-3 sensors. The models, based on spectral band indices, were validated with data from the hyperspectral sensor HICO, onboard of the International Space Station.[ES] La concentración de clorofila-a es uno de los principales indicadores de la calidad de las aguas continentales.
A partir de imágenes del sensor CHRIS/PROBA y de datos obtenidos en campañas de medida en lagos en Colombia y
España, se han obtenido modelos empíricos para la estimación de la concentración de clorofila-a, directamente aplicables
a los futuros sensores de la ESA, MSI de Sentinel-2 y OLCI de Sentinel-3. Los modelos, basados en índices de bandas
espectrales, se han validado con datos del sensor hiperespectral HICO, a bordo de la Estación Espacial Internacional.Se agradece al CEDEX por facilitarnos los datos de radiometría in situ y de [Chl-a] del Embalse de Rosarito y La Albufera, y al Grupo de Ecología de la Universidad de Valencia por los datos de [Chl-a] medidos en la Albufera.Delegido, J.; Tenjo, C.; Ruiz-Verdú, A.; Peña, R.; Moreno, J. (2014). Modelo empírico para la determinación de clorofila-a en aguas continentales a partir de los futuros Sentinel-2 y 3. Validación con imágenes HICO. Revista de Teledetección. (41):37-47. doi:10.4995/raet.2014.2295.SWORD374741Alonso, L., Gomez-Chova, L., Moreno, J., Guanter, L., Brockmann, C., Fomferra, N., … Regner, P. (2009). CHRIS/Proba Toolbox for hyperspectral and multiangular data exploitations. 2009 IEEE International Geoscience and Remote Sensing Symposium. doi:10.1109/igarss.2009.5418041Dall’Olmo, G., & Gitelson, A. A. (2006). Effect of bio-optical parameter variability and uncertainties in reflectance measurements on the remote estimation of chlorophyll-a concentration in turbid productive waters: modeling results. Applied Optics, 45(15), 3577. doi:10.1364/ao.45.003577Odermatt, D., Gitelson, A., Brando, V. E., & Schaepman, M. (2012). Review of constituent retrieval in optically deep and complex waters from satellite imagery. Remote Sensing of Environment, 118, 116-126. doi:10.1016/j.rse.2011.11.013Soria, J. M., Vicente, E., 2002. Estudios de los aportes hídricos al parque natural de la Albufera de Valencia. Limnetica, 2, 105-115
Identification and evaluation of semiochemicals for the biological control of the beetle Omorgus suberosus (F.) (Coleoptera: Trogidae), a facultative predator of eggs of the sea turtle Lepidochelys olivacea (Eschscholtz)
The beetle Omorgus suberosus (F.) is a facultative predator of eggs of the olive ridley turtle Lepidochelys olivacea (Eschscholtz). Laboratory and field investigations were conducted in order to characterize volatile attractants of O. suberosus and to explore the potential for application of these volatiles in a selective mass trapping method. Headspace sorptive extraction (HSSE) coupled to thermo-desorption gas chromatography–mass spectrometry (TD-GC-MS) analysis of the volatile constituents from beetles or turtle nests revealed 24 potential compounds. However, electroantennographic (EAG) measurements revealed antennal sensitivity only to indole, linoleic acid, trimethylamine, dimethyl sulphide, dimethyl disulphide and ammonia. Behavioural tests showed that these compounds are highly attractive to O. suberosus. Field trapping experiments revealed that indole and ammonia were more attractive than the other volatile compounds and showed similar attractiveness to that produced by conventional baits (chicken feathers). The use of a combined bait of indole and NH3 would therefore be the most effective trap design. The data presented are the first to demonstrate effective massive capture of O. suberosus using an attractant-based trapping method. These findings have potential for the development of an efficient mass trapping method for control of this beetle as part of efforts towards conservation of L. olivacea at La Escobilla in Oaxaca, Mexico.The study was funded by the Programa de Conservación de Especies en Riesgo (PROCER) and the Dirección de Especies Prioritarias para la Conservación of the National Commission of Natural Protected Areas (CONANP) to GH. We are also grateful to INECOL A.C. for financial support awarded to GH. This research was fully funded by the National Commission for Protected Natural Areas (CONANP–Mexico)
Isolation and determination of ivermectin in post-mortem and in vivo tissues of dung beetles using a continuous solid phase extraction method followed by LC-ESI+-MS/MS
A new analytical method based on solvent extraction, followed by continuous solid-phase extraction (SPE) clean-up using a polymeric sorbent, was demonstrated to be applicable for the detection of ivermectin in complex biological matrices of dung beetles (hemolymph, excreta or dry tissues) using liquid chromatography combined with positive electrospray ionization tandem mass spectrometry (LC/ESI+–MS/MS). Using a signal-to-noise ratio of 3:1, the limit of detection (LOD) in the insect matrices at trace levels was 0.01 ng g–1 and the limit of quantification (LOQ) was 0.1 ng g–1. The proposed method was successfully used to quantitatively determine the levels of ivermectin in the analysis of small samples in in vivo and post mortem samples, demonstrating the usefulness for quantitative analyses that are focused on future pharmacokinetic and bioavailability studies in insects and the establishment of a new protocol to study the impact of ivermectin on non-target arthropods such as dung beetles and other insects that are related with the “dung community”. Because satisfactory precision and accuracy values were obtained in both in vivo matrices, we suggest that the method can be consistently used for quantitative determinations that are focused on future pharmacokinetic and bioavailability studies in insects. Furthermore, this new analytical method was successfully applied to biological samples of dead dung beetles from the field suggesting that the method can be used to establish a new routine analysis of ivermectin residues in insect carcasses that is applied to complement typical mortality tests.Financial support was provided by Project CGL2015-68207-R of the Secretaría de Estado de Investigación–Ministerio de Economía y Competitividad, and by the Project OAPN 762/2012 of the Organismo Autónomo de Parques Nacionales-Ministerio de Agricultura, Alimentación y Medio Ambiente
Statistical mechanical analysis of the linear vector channel in digital communication
A statistical mechanical framework to analyze linear vector channel models in
digital wireless communication is proposed for a large system. The framework is
a generalization of that proposed for code-division multiple-access systems in
Europhys. Lett. 76 (2006) 1193 and enables the analysis of the system in which
the elements of the channel transfer matrix are statistically correlated with
each other. The significance of the proposed scheme is demonstrated by
assessing the performance of an existing model of multi-input multi-output
communication systems.Comment: 15 pages, 2 figure
Design and Vertical Tests of SPS-series Double-Quarter Wave (DQW) Cavity Prototypes for the HL-LHC Crab Cavity System
Crab crossing is essential for high-luminosity colliders. The High Luminosity
Large Hadron Collider (HL-LHC) will equip one of its Interaction Points (IP1)
with Double-Quarter Wave (DQW) crab cavities. A DQW cavity is a new generation
of deflecting RF cavities that stands out for its compactness and broad
frequency separation between fundamental and first high-order modes. The
deflecting kick is provided by its fundamental mode. Each HL-LHC DQW cavity
shall provide a nominal deflecting voltage of 3.4 MV, although up to 5.0 MV may
be required. A Proof-of-Principle (PoP) DQW cavity was limited by quench at 4.6
MV. This paper describes a new, highly optimized cavity, designated DQW
SPS-series, which satisfies dimensional, cryogenic, manufacturing and impedance
requirements for beam tests at SPS and operation in LHC. Two prototypes of this
DQW SPS-series were fabricated by US industry and cold tested after following
conventional SRF surface treatment. Both units outperformed the PoP cavity,
reaching a deflecting voltage of 5.3-5.9 MV. This voltage - the highest reached
by a DQW cavity - is well beyond the nominal voltage of 3.4 MV and may even
operate at the ultimate voltage of 5.0MVwith sufficient margin. This paper
covers fabrication, surface preparation and cryogenic RF test results and
implications
Trapped electron coupled to superconducting devices
We propose to couple a trapped single electron to superconducting structures
located at a variable distance from the electron. The electron is captured in a
cryogenic Penning trap using electric fields and a static magnetic field in the
Tesla range. Measurements on the electron will allow investigating the
properties of the superconductor such as vortex structure, damping and
decoherence. We propose to couple a superconducting microwave resonator to the
electron in order to realize a circuit QED-like experiment, as well as to
couple superconducting Josephson junctions or superconducting quantum
interferometers (SQUIDs) to the electron. The electron may also be coupled to a
vortex which is situated in a double well potential, realized by nearby pinning
centers in the superconductor, acting as a quantum mechanical two level system
that can be controlled by a transport current tilting the double well
potential. When the vortex is trapped in the interferometer arms of a SQUID,
this would allow its detection both by the SQUID and by the electron.Comment: 13 pages, 5 figure
Some Recent Advances in Bound-State Quantum Electrodynamics
We discuss recent progress in various problems related to bound-state quantum
electrodynamics: the bound-electron g factor, two-loop self-energy corrections
and the laser-dressed Lamb shift. The progress relies on various advances in
the bound-state formalism, including ideas inspired by effective field theories
such as Nonrelativistic Quantum Electrodynamics. Radiative corrections in
dynamical processes represent a promising field for further investigations.Comment: 12 pages, nrc1 LaTeX styl
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