New developments in the THz field for imaging applications

Con esta tesis se pretende avanzar en el desarrollo de la tecnología de terahercios (THz) dentro del campo de las aplicaciones de imagen. Actualmente, los THz se presentan como un rango frecuencial muy interesante para la obtención de imágenes, tal y como se ve reflejado en los numerosos trabajos presentes en la literatura. Por otro lado, aunque se han obtenido cuantiosas imágenes en este rango, aun no es posible identificar el material que compone la muestra. Es por esto que uno de los objetivos de esta tesis es completar las bases de datos de materiales existentes actualmente. Para ello, se han implementado diferentes sistemas que permiten la caracterización electromagnética de diferentes materiales en el rango de los THz.The aim of this thesis is to go a step forward in the use of terahertz (THz) technology within the field of imaging applications. Nowadays, THz radiation appears as a very interesting frequency range to obtain images, as related in the numerous publications. Conversely, although there are several examples of imaging in this range, it is still not possible to identify the material that it is imaged. That is why one of the objectives of this thesis will be to add new materials to the actual database. Thus, several systems have been implemented to characterize materials in the range of THz for this dissertation.Programa Oficial de Doctorado en Tecnologías de las Comunicaciones (RD 1393/2007)Komunikazioen Teknologietako Doktoretza Programa Ofiziala (ED 1393/2007

The aquatic ecosystem, a good environment for the horizontal transfer of antimicrobial resistance and virulence-associated factors among extended spectrum beta-lactamases producing E. coli

One of the main public health problems nowadays is the increase of antimicrobial resistance, both in the hospital environment and outside it (animal environment, food and aquatic ecosystems, among others). It is necessary to investigate the virulence-associated factors and the ability of horizontal gene transfer among bacteria for a better understanding of the pathogenicity and the mechanisms of dissemination of resistant bacteria. Therefore, the objective of this work was to detect several virulence factors genes (fimA, papC, papG III, cnf1, hlyA and aer) and to determine the conjugative capacity in a wide collection of extended-spectrum β-lactamases-producing E. coli isolated from different sources (human, food, farms, rivers, and wastewater treatment plants). Regarding virulence genes, fimA, papC, and aer were distributed throughout all the studied environments, papG III was mostly related to clinical strains and wastewater is a route of dissemination for cnf1 and hlyA. Strains isolated from aquatic environments showed an average conjugation frequencies of 1.15 × 10−1 ± 5 × 10−1 , being significantly higher than those observed in strains isolated from farms and food (p < 0.05), with frequencies of 1.53 × 10−4 ± 2.85 × 10−4 and 9.61 × 10−4 ± 1.96 × 10−3 , respectively. The reported data suggest the importance that the aquatic environment (especially WWTPs) acquires for the exchange of genes and the dispersion of resistance. Therefore, specific surveillance programs of AMR indicators in wastewaters from animal or human origin are needed, in order to apply sanitation measures to reduce the burden of resistant bacteria arriving to risky environments as WWTPs

The aquatic ecosystem, a good environment for the horizontal transfer of antimicrobial resistance and virulence-associated factors among extended spectrum ß-lactamases producing E. coli

One of the main public health problems nowadays is the increase of antimicrobial resistance, both in the hospital environment and outside it (animal environment, food and aquatic ecosystems, among others). It is necessary to investigate the virulence-associated factors and the ability of horizontal gene transfer among bacteria for a better understanding of the pathogenicity and the mechanisms of dissemination of resistant bacteria. Therefore, the objective of this work was to detect several virulence factors genes (fimA, papC, papG III, cnf1, hlyA and aer) and to determine the conjugative capacity in a wide collection of extended-spectrum β-lactamases-producing E. coli isolated from different sources (human, food, farms, rivers, and wastewater treatment plants). Regarding virulence genes, fimA, papC, and aer were distributed throughout all the studied environments, papG III was mostly related to clinical strains and wastewater is a route of dissemination for cnf1 and hlyA. Strains isolated from aquatic environments showed an average conjugation frequencies of 1.15 × 10−1 ± 5 × 10−1 , being significantly higher than those observed in strains isolated from farms and food (p < 0.05), with frequencies of 1.53 × 10−4 ± 2.85 × 10−4 and 9.61 × 10−4 ± 1.96 × 10−3 , respectively. The reported data suggest the importance that the aquatic environment (especially WWTPs) acquires for the exchange of genes and the dispersion of resistance. Therefore, specific surveillance programs of AMR indicators in wastewaters from animal or human origin are needed, in order to apply sanitation measures to reduce the burden of resistant bacteria arriving to risky environments as WWTPs

Multidrug-Resistant Bacteria Isolated from Different Aquatic Environments in the North of Spain and South of France

Due to the global progress of antimicrobial resistance, the World Health Organization (WHO) published the list of the antibiotic-resistant “priority pathogens” in order to promote research and development of new antibiotics to the families of bacteria that cause severe and often deadly infections. In the framework of the One Health approach, the surveillance of these pathogens in different environments should be implemented in order to analyze their spread and the potential risk of transmission of antibiotic resistances by food and water. Therefore, the objective of this work was to determine the presence of high and critical priority pathogens included in the aforementioned list in different aquatic environments in the POCTEFA area (North Spain–South France). In addition to these pathogens, detection of colistin-resistant Enterobacteriaceae was included due its relevance as being the antibiotic of choice to treat infections caused by multidrug resistant bacteria (MDR). From the total of 80 analyzed samples, 100% of the wastewater treatment plants (WWTPs) and collectors (from hospitals and slaughterhouses) and 96.4% of the rivers, carried antibiotic resistant bacteria (ARB) against the tested antibiotics. Fifty-five (17.7%) of the isolates were identified as target microorganisms (high and critical priority pathogens of WHO list) and 58.2% (n = 32) of them came from WWTPs and collectors. Phenotypic and genotypic characterization showed that 96.4% were MDR and resistance to penicillins/cephalosporins was the most widespread. The presence of bla genes, KPC-type carbapenemases, mcr-1 and vanB genes has been confirmed. In summary, the presence of clinically relevant MDR bacteria in the studied aquatic environments demonstrates the need to improve surveillance and treatments of wastewaters from slaughterhouses, hospitals and WWTPs, in order to minimize the dispersion of resistance through the effluents of these areas

Prevalence of integrons and insertion sequences in ESBL-producing E-coli isolated from different sources in Navarra, Spain

Mobile genetic elements play an important role in the dissemination of antibiotic resistant bacteria among human and environmental sources. Therefore, the aim of this study was to determine the occurrence and patterns of integrons and insertion sequences of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli isolated from different sources in Navarra, northern Spain. A total of 150 isolates coming from food products, farms and feeds, aquatic environments, and humans (healthy people and hospital inpatients), were analyzed. PCRs were applied for the study of class 1, 2, and 3 integrons (intI1, intI2, and intI3), as well as for the determination of insertion sequences (IS26, ISEcp1, ISCR1, and IS903). Results show the wide presence and dissemination of intI1 (92%), while intI3 was not detected. It is remarkable, the prevalence of intI2 among food isolates, as well as the co-existence of class 1 and class 2 (8% of isolates). The majority of isolates have two or three IS elements, with the most common being IS26 (99.4%). The genetic pattern IS26–ISEcp1 (related with the pathogen clone ST131) was present in the 22% of isolates (including human isolates). In addition, the combination ISEcp1–IS26–IS903–ISCR1 was detected in 11 isolates being, to our knowledge, the first study that describes this genetic complex. Due to the wide variability observed, no relationship was determined among these mobile genetic elements and β-lactam resistance. More investigations regarding the genetic composition of these elements are needed to understand the role of multiple types of integrons and insertion sequences on the dissemination of antimicrobial resistance genes among different environments

Compact Dual-Band Terahertz Quarter-Wave Plate Metasurface

“© © 20xx IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.”A dual-band quarter-wave plate based on a modified extraordinary transmission hole array is numerically analyzed and experimentally demonstrated at terahertz frequencies. To control independently orthogonal polarizations, the original square holes are connected with vertical slits and their lateral straight sides are replaced by meander lines. This smart design enables dual-band operation with unprecedented fractional bandwidths in a compact structure. Considering a flattening deviation lower than 40% of the optimum value, a fractional bandwidth of 53.8% and 3.8% is theoretically obtained (16.8% and 2.9% in the experiment) at 1 and 2.2 THz, respectively. At these two frequencies, the structure is 0.13-lambda and 0.29-lambda thick, respectively. Given the compactness of the whole structure and the performance obtained, this quarter-wave plate is presented as a competitive device for the terahertz band.This work was supported by the Spanish Government through the Consolider Engineering Metamaterials under Contract CSD2008-00066 and Contract TEC2011-28664-C02.Torres, V.; Sánchez Losilla, N.; Etayo, D.; Ortuño Molinero, R.; Navarro-Cía, M.; Martínez Abietar, AJ.; Beruete, M. (2014). Compact Dual-Band Terahertz Quarter-Wave Plate Metasurface. IEEE Photonics Technology Letters. 26(16):1679-1682. https://doi.org/10.1109/LPT.2014.2330860S16791682261

Extraordinary Transmission-inspired Dual-band THz Quarter-wave Plate

[EN] We propose a very compact metasurface that works as a quarter-wave plate at two different frequencies, 1 THz and 2.2 THz. The fractional bandwidth of the first band is remarkably 32.2%, beyond the state-of-the-artThis work was supported in part by the Spanish Government under Contract Consolider Engineering Metamaterials CSD2008-00066 and contract TEC2011-28664-C02. M. Navarro-Cía acknowledges his IC Junior Research FellowshipTorres, V.; Sánchez, N.; Etayo, D.; Ortuño, R.; Martínez Abietar, AJ.; Navarro-Cía, M.; Beruete, M. (2014). Extraordinary Transmission-inspired Dual-band THz Quarter-wave Plate. OSA. 1-2. https://doi.org/10.1364/CLEO_SI.2014.STh3F.8S1

Towards standardisation of contact and contactless electrical measurements of CVD graphene at the macro-, micro- and nano-scale

Graphene has become the focus of extensive research efforts and it can now be produced in wafer-scale. For the development of next generation graphene-based electronic components, electrical characterization of graphene is imperative and requires the measurement of work function, sheet resistance, carrier concentration and mobility in both macro-, micro- and nano-scale. Moreover, commercial applications of graphene require fast and large-area mapping of electrical properties, rather than obtaining a single point value, which should be ideally achieved by a contactless measurement technique. We demonstrate a comprehensive methodology for measurements of the electrical properties of graphene that ranges from nano- to macro- scales, while balancing the acquisition time and maintaining the robust quality control and reproducibility between contact and contactless methods. The electrical characterisation is achieved by using a combination of techniques, including magneto-transport in the van der Pauw geometry, THz time-domain spectroscopy mapping and calibrated Kelvin probe force microscopy. The results exhibit excellent agreement between the different techniques. Moreover, we highlight the need for standardized electrical measurements in highly controlled environmental conditions and the application of appropriate weighting functions

Information Processing in the Orbitofrontal Cortex and the Ventral Striatum in Rats Performing an Economic Decision-Making Task

University of Minnesota Ph.D. dissertation. August 2015. Major: Neuroscience. Advisor: David Redish. 1 computer file (PDF); vi, 144 pages.The orbitofrontal cortex (OFC) and ventral striatum (vStr) are key brain structures that represent information about value during decision-making tasks. Despite their very different anatomical properties, numerous studies have found similar patterns of value-related signaling in these structures. In particular, both structures are intimately involved in delay-discounting tasks, which involve a tradeoff between reward magnitude and delay to reward. However, the overlapping activity profiles of these brain regions makes it difficult to tease apart their specific contributions to delay-discounting behavior, and to economic decision-making more generally. In order to better understand the contributions of these two regions to value-based choice, we made simultaneous recordings in the OFC and vStr in rats performing a spatial variant of a traditional delay-discounting task. This allowed us to compare OFC and vStr activity directly in the same subjects while they engaged in a prototypical economic decision-making task, and additionally it allowed us to leverage the tools of spatial decoding analysis to measure non-local reward signaling. Chapter 1 provides an introduction to current theories of OFC and vStr function within the decision-making literature, in particular contrasting the concepts of neuroeconomics with the multiple decision-making systems framework. Chapter 2 describes the methods used in this thesis, including the design of the spatial delay-discounting task and the analysis of the neural data. Chapter 3 presents the results of single-unit and Bayesian decoding analyses from this dataset. We found that activity in the OFC and vStr was quite similar at the single-unit level, and inconsistent with the neuroeconomic account of value signaling in a common currency. Instead, when we looked specifically at moments of deliberative decision-making (as emphasized by the multiple systems account), we found important differences between the OFC and vStr. Both the OFC and the vStr showed covert reward signaling during deliberative, vicarious trial-and-error (VTE) behaviors. But vStr signals emerged earlier, before the moment of choice, while covert reward coding in the OFC appeared after the rats had committed to their decision. These analyses were extended to the level of local field potentials (LFPs), recorded from the same dataset. Local field potentials are a useful tool for studying local processing and interactions between brain regions. Chapter 4 describes the LFP results. Important among these was the finding that the vStr led the OFC at the LFP level (again showing temporal precedence), and furthermore, that the vStr was a stronger driver of OFC activity than vice versa, particularly during VTE. The implications of these results, along with those from the single-unit and Bayesian decoding analyses, are discussed in Chapter 5. Emphasis is placed on our emerging understanding of the role of the vStr in flexible behavior, and how the OFC and the vStr might cooperate to influence value-based choice