387 research outputs found
Directional coupling of emitters into waveguides: A symmetry perspective
Recent experiments demonstrated strongly directional coupling of light into
waveguide modes. We identify here the mechanisms behind this effect. We
consider emitters near a waveguide, either centered on the median plane of the
waveguide, or displaced from such plane. We show that, independently of the
displacement, the directionality is mostly due to a mirror symmetry breaking
caused by the axial character of the angular momentum of the emitted light. The
sign of the angular momentum along an axis transverse to the waveguide
determines the preferential coupling direction. The degree of directionality
grows exponentially as the magnitude of such transverse angular momentum
increases linearly. We trace this exponential dependence back to a property of
the evanescent angular spectrum of the emissions. A binary and less pronounced
directional coupling effect due to the chiral character of the handedness of
the emission is possible when the displacement of the emitter breaks another of
the mirror symmetries of the waveguide. We find a selection rule that allows or
prevents the coupling of centered electric(magnetic) multipolar emissions onto
the waveguide modes. We also show that the selection of a different angular
momentum axis made in some experiments causes significant differences in the
way in which directionality depends on angular momentum. We then use these
differences to propose an experiment featuring a transverse magnetic bias that
allows to aggregate the directional emissions from quantum dots on top of
waveguides. Our symmetry-based results apply to any emitted multipolar order,
clarify the spin-momentum locking concept, and generalize it to an
exponentially-strong locking between the transverse angular momentumand the
preferential coupling direction
Response Surface Method to Calculate Energy Savings Associated with Thermal Comfort Improvement in Buildings
In developed countries, a large part of the building stock in 2050 will consist of currently existing buildings. Consequently, in order to achieve the objectives in terms of energy efficiency in the building sector we must consider not only new infrastructures but also the old ones. A reduction in energy consumption for climate control of between 50 and 90% can be achieved by rehabilitation and the implementation of different energy efficiency measures. Currently, these measures to reduce energy consumption and associated CO2 emissions can be modelled using computer tools. However, high precision and detail of thermal behaviour models through simulations can mean a great computational cost for companies, which results in a blockage of servers and workers. In this paper, the Response Surface Methodology (RSM) is presented as an innovative methodology for the simplification of models for calculation of the energy savings associated with thermal comfort improvement in buildings. A single-family house model, located in three different climates, is presented as a case study in order to validate the proposed methodology. Different scenarios were simulated, addressing heating and cooling temperature set points and external wall insulation represented by the transmittance (U-value). Results obtained from energy simulation using Design Builder were contrasted against those estimated from the simplified model extracted from the RSM analysis. The results revealed a deviation lower than 3% when comparing both methods. Therefore, the simplified mathematical prediction models are demonstrated to be suitable for the study of the energy performance of buildings, saving computational time, costs and associated human resources. © 2022 by the authors. Licensee MDPI, Basel, Switzerland
Bio-Assisted Tailored Synthesis of Plasmonic Silver Nanorings and Site-Selective Deposition on Graphene Arrays
The spontaneous interaction between noble metals and biological scaffolds enables simple and cost-effective synthesis of nanomaterials with unique features. Here, plasmonic silver nanorings are synthesized on a ring-like protein, i.e., a peroxiredoxin (PRX), and used to assemble large arrays of functional nanostructures. The PRX drives the seeding growth of metal silver under wet reducing conditions, yielding nanorings with outer and inner diameters down to 28 and 3 nm, respectively. The obtained hybrid nanostructures are selectively deposited onto a solid-state 2D membrane made of graphene in order to prepare plasmonic nanopores. In particular, the interaction between the graphene and the PRX allows for the simple preparation of ordered arrays of plasmonic nanorings on a 2D-material membrane. This fabrication process can be finalized by drilling a nanometer scale pore in the middle of the ring. Fluorescence spectroscopic measurements in combination with numerical simulations demonstrate the plasmonic effects induced in the metallic nanoring cavity. The prepared nanopores represent one of the first examples of hybrid plasmonic nanopore structures integrated on a 2D-material membrane. The diameter of the nanopore and the atomically thick substrate make this proof-of-concept approach particularly interesting for nanopore-based technologies and applications such as next-generation sequencing and single-molecule detection
Hybrid Metal-Dielectric Plasmonic Zero Mode Waveguide for Enhanced Single Molecule Detection
We fabricated hybrid metal-dielectric nanoantennas and measured their optical
response at three different wavelengths. The nanostructure is fabricated on a
bilayer film formed by the sequential deposition of silicon and gold on a
transparent substrate. The optical characterization is done via fluorescence
measurements. We characterized the fluorescence enhancement, as well as the
lifetime and detection volume reduction for each wavelength. We observe that
the hybrid metal-dielectric nanoantennas behave as enhanced Zero Mode
Waveguides in the near-infrared spectral region. Their detection volume is such
that they can perform enhanced single-molecule detection at tens of microM.
However, a wavelength blue-shift of 40 nm dramatically decreases the
performance of the nanoantennas. We compared their behavior with that of a
golden ZMW, and we verified that the dielectric silicon layer improves the
design. We interpreted the experimental observations with the help of numerical
simulations. In addition, the simulations showed that the field enhancement of
the structure highly depends on the incoming beam: tightly focused beams yield
lower field enhancements than plane-waves
Ethnobotanical knowledge is vastly under-documented in northwestern South America
A main objective of ethnobotany is to document traditional knowledge about plants before it disappears. However, little is known about the coverage of past ethnobotanical studies and thus about how well the existing literature covers the overall traditional knowledge of different human groups. To bridge this gap, we investigated ethnobotanical data-collecting efforts across four countries (Colombia, Ecuador, Peru, Bolivia), three ecoregions (Amazon, Andes, ChocĂł), and several human groups (including Amerindians, mestizos, and Afro-Americans). We used palms (Arecaceae) as our model group because of their usefulness and pervasiveness in the ethnobotanical literature. We carried out a large number of field interviews (n = 2201) to determine the coverage and quality of palm ethnobotanical data in the existing ethnobotanical literature (n = 255) published over the past 60 years. In our fieldwork in 68 communities, we collected 87,886 use reports and documented 2262 different palm uses and 140 useful palm species. We demonstrate that traditional knowledge on palm uses is vastly under-documented across ecoregions, countries, and human groups. We suggest that the use of standardized data-collecting protocols in wide-ranging ethnobotanical fieldwork is a promising approach for filling critical information gaps. Our work contributes to the Aichi Biodiversity Targets and emphasizes the need for signatory nations to the Convention on Biological Diversity to respond to these information gaps. Given our findings, we hope to stimulate the formulation of clear plans to systematically document ethnobotanical knowledge in northwestern South America and elsewhere before it vanishesThis study was funded by the European Union, 7th Framework Programme (contract no. 212631), the Russel E. Train Education for Nature Program of
the WWF (to NPZ), the Anne S. Chatham fellowship of the Garden Club of America (to NPZ), and the Universidad AutĂłnoma de Madrid travel grants programme
(to RCL
PrevenciĂłn del cĂłlera aviar con extractos acuosos de plantas en pollos de engorde.
De octubre a diciembre de 1992, con extractos acuosos de las plantas, se realizaron, anfitoquĂmicos y pruebas microbiolĂłgicas en la bacteria Pasteurella multocida. La etapa de campo se realizĂł en la Granja Escuela de CapacitaciĂłn Cooperativa Agropecuaria (GECA) en Chalatenango, El Salvador. Se evaluaron 16 tratamientos: cuatro plantas individuales, sus posibles combinaciones y el testigo. Se sometieron pollos de engorde, de la lĂnea Arbos Acres, a la inoculaciĂłn de la bacteria, para determinar el resultado preventivo de los tratamientos. Con el modelo de Weibull y la funciĂłn de supervivencia se obtuvo significancia estadĂstica solamente para los tratamientos con las combinaciones (Quina-Epacina, Palo hediondo-Tempate, Palo hediondo- Epacina y Quina- Tempate - Palo hediondo-Epacina; Ă©ste Ăşltimo tratamiento fue el mejor para la prevenciĂłn del cĂłlera aviar
Comparison of breast and bowel cancer screening uptake patterns in a common cohort of South Asian women in England
Background: Inequalities in uptake of cancer screening by ethnic minority populations are well documented in a
number of international studies. However, most studies to date have explored screening uptake for a single cancer
only. This paper compares breast and bowel cancer screening uptake for a cohort of South Asian women invited to
undertake both, and similarly investigates these women's breast cancer screening behaviour over a period of fifteen
years.
Methods: Screening data for rounds 1, 2 and 5 (1989-2004) of the NHS breast cancer screening programme and for
round 1 of the NHS bowel screening pilot (2000-2002) were obtained for women aged 50-69 resident in the English
bowel screening pilot site, Coventry and Warwickshire, who had been invited to undertake breast and bowel cancer
screening in the period 2000-2002. Breast and bowel cancer screening uptake levels were calculated and compared
using the chi-squared test.
Results: 72,566 women were invited to breast and bowel cancer screening after exclusions. Of these, 3,539 were South
Asian and 69,027 non-Asian; 18,730 had been invited to mammography over the previous fifteen years (rounds 1 to 5).
South Asian women were significantly less likely to undertake both breast and bowel cancer screening; 29.9% (n =
1,057) compared to 59.4% (n = 40,969) for non-Asians (p < 0.001). Women in both groups who consistently chose to
undertake breast cancer screening in rounds 1, 2 and 5 were more likely to complete round 1 bowel cancer screening.
However, the likelihood of completion of bowel cancer screening was still significantly lower for South Asians; 49.5% vs.
82.3% for non-Asians, p < 0.001. South Asian women who undertook breast cancer screening in only one round were
no more likely to complete bowel cancer screening than those who decided against breast cancer screening in all
three rounds. In contrast, similar women in the non-Asian population had an increased likelihood of completing the
new bowel cancer screening test. The likelihood of continued uptake of mammography after undertaking screening in
round 1 differed between South Asian religio-linguistic groups. Noticeably, women in the Muslim population were less
likely to continue to participate in mammography than those in other South Asian groups.
Conclusions: Culturally appropriate targeted interventions are required to reduce observed disparities in cancer
screening uptakes
Non-Invasive Device for Blood Pressure Wave Acquisition by Means of Mechanical Transducer
Blood pressure wave monitoring provides interesting information about the patient’s cardiovascular function. For this reason, this article proposes a non-invasive device capable of capturing the vibrations (pressure waves) produced by the carotid artery by means of a pressure sensor encapsulated in a closed dome filled with air. When the device is placed onto the outer skin of the carotid area, the vibrations of the artery will exert a deformation in the dome, which, in turn, will lead to a pressure increase in its inner air. Then, the sensor inside the dome captures this pressure increase. By combining the blood pressure wave obtained with this device together with the ECG signal, it is possible to help the screening of the cardiovascular system, obtaining parameters such as heart rate variability (HRV) and pulse transit time (PTT). The results show how the pressure wave has been successfully obtained in the carotid artery area, discerning the characteristic points of this signal. The features of this device compare well with previous works by other authors. The main advantages of the proposed device are the reduced size, the cuffless condition, and the potential to be a continuous ambulatory device. These features could be exploited in ambulatory tests.D.Z.V. thanks the economic support of the ACIF (subsidies for the recruitment of predoctoral research staff) program with the scholarship ACIF/2019/058. The work of J.M.V.-S. was supported by Conselleria d’Educació, Investigació, Cultura i Esport (GVA) through FDGENT/2018/015 project. The work of C.G.J. was funded by the Spanish Ministry of Education, Culture, and Sport through the Research and Doctorate Supporting Program FPU, grant number FPU14/00401. This work was partially funded by Spanish Research State Agency and European Regional Development Fund through “Craneeal” Project (DPI2106-80391-C3-2-R)
An NLO QCD analysis of inclusive cross-section and jet-production data from the ZEUS experiment
The ZEUS inclusive differential cross-section data from HERA, for charged and
neutral current processes taken with e+ and e- beams, together with
differential cross-section data on inclusive jet production in e+ p scattering
and dijet production in \gamma p scattering, have been used in a new NLO QCD
analysis to extract the parton distribution functions of the proton. The input
of jet data constrains the gluon and allows an accurate extraction of
\alpha_s(M_Z) at NLO;
\alpha_s(M_Z) = 0.1183 \pm 0.0028(exp.) \pm 0.0008(model)
An additional uncertainty from the choice of scales is estimated as \pm
0.005. This is the first extraction of \alpha_s(M_Z) from HERA data alone.Comment: 37 pages, 14 figures, to be submitted to EPJC. PDFs available at
http://durpdg.dur.ac.uk/hepdata in LHAPDFv
Search for lepton-flavor violation at HERA
A search for lepton-flavor-violating interactions and has been performed with the ZEUS detector using the entire HERA I
data sample, corresponding to an integrated luminosity of 130 pb^{-1}. The data
were taken at center-of-mass energies, , of 300 and 318 GeV. No
evidence of lepton-flavor violation was found, and constraints were derived on
leptoquarks (LQs) that could mediate such interactions. For LQ masses below
, limits were set on , where
is the coupling of the LQ to an electron and a
first-generation quark , and is the branching ratio of
the LQ to the final-state lepton ( or ) and a quark . For
LQ masses much larger than , limits were set on the four-fermion
interaction term for LQs that couple to an electron and a quark
and to a lepton and a quark , where and are
quark generation indices. Some of the limits are also applicable to
lepton-flavor-violating processes mediated by squarks in -Parity-violating
supersymmetric models. In some cases, especially when a higher-generation quark
is involved and for the process , the ZEUS limits are the most
stringent to date.Comment: 37 pages, 10 figures, Accepted by EPJC. References and 1 figure (Fig.
6) adde
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