Corporate hosts: the rise of professional management in the short-term rental industry

This paper explores the rise of short-term rental (STR) management companies and reveals the transition from a sharing economy activity to the consolidation of a professional industry hinging on what we call ‘corporate hosts’. By relying on interviews with companies operating in Lisbon and Porto, Portugal, we found: first, that a phenomenon of market concentration occurred in which individual hosts have outsourced the management of their properties to corporate hosts; second, that through the use of digital technology and vertical integration, corporate hosts are able to enhance the profitability of large portfolios of STRs; and, third, that corporate hosts imitate practices from the hotel industry, leading to the formation of a hybrid product in which the lines between hotels and STRs have blurred. We argue that corporate hosts constitute a new layer of intermediation that challenges the way we understand the STR industry and the overall functioning of this market.info:eu-repo/semantics/publishedVersio

Current-, force-, and vibration-based techniques for induction motor condition monitoring

The aim of this research was to discover the best indicators of induction motor faults, as well as suitable techniques for monitoring the condition of induction motors. Numerical magnetic field analysis was used with the objective of generating reliable virtual data to be analysed with modern signal processing and soft-computing techniques. In the first part of the research, a fuzzy system, based on the amplitudes of the motor current, was implemented for online detection of stator faults. Later on, from the simulation studies and using support vector machine (SVM), the electromagnetic force was shown to be the most reliable indicator of motor faults. Discrete wavelet transform (DWT) was applied to the stator current during the start-up transient, showing how the evolution of some frequency components allows the identification and discrimination of induction motor faults. Predictive filtering was applied to separate the harmonic components from the main current signal. The second part of the research was devoted to the development of a mechanical model to study the effects of electromagnetic force on the vibration pattern when the motor is working under fault conditions. The third part of this work, following the indications given by the second part, is concerned with a method that allows the prediction of the effect of the electromechanical faults in the force distribution and vibration pattern of the induction machines. The FEM computations show the existence of low-frequency and low-order force distributions acting on the stator of the electrical machine when it is working under an electrical fault. It is shown that these force components are able to produce forced vibration in the stator of the machine. This is corroborated by vibration measurements. These low-frequency components could constitute the primary indicator in a condition monitoring system. During the research, extensive measurements of current, flux and vibration were carried out in order to supply data for the research group. Various intentional faults, such as broken rotor bars, broken end ring, inter-turn short circuit, bearing and eccentricity failures, were created. A real dynamic eccentricity was also created. Moreover, different supply sources were used. The measurements supported the analytical and numerical results.reviewe

Air-gap force distribution and vibration pattern of Induction motors under dynamic eccentricity

[EN] A method for determining the signatures of dynamic eccentricity in the airgap force distribution and vibration pattern of induction machine is presented. The radial electromagnetic force distribution along the airgap, which is the main source of vibration, is calculated and developed into a double Fourier series in space and time. Finite element simulations of faulty and healthy machines are performed. They show that the electromagnetic force distribution is a sensible parameter to the changes in the machine condition. The computations show the existence of low frequency and low order force distributions, which can be used as identifiable signatures of the motor condition by measuring the corresponding low order vibration components. These findings are supported by vibration measurements and modal testing. The low frequency components offer an alternative way to the monitoring of slot passing frequencies, bringing new components that allow to discriminate between dynamic eccentricity and rotor mechanical unbalance. The method also revealed a non linear relationship between loading, stress waves and vibration during dynamic eccentricity.Jover Rodríguez, PV.; Belahcen, A.; Arkkio, A.; Laiho, A.; Antonino-Daviu, J. (2008). Air-gap force distribution and vibration pattern of Induction motors under dynamic eccentricity. Electrical Engineering. 90(3):209-218. doi:10.1007/s00202-007-0066-2S209218903Rao JS (2000). Vibratory condition monitoring of machines. CRC Pr. Llc., Boca RatonTavner P, Penman J (1987) Condition monitoring of electrical machines. Research Studies Press, Letchworth, pp 203–205Pöyhönen S, Negrea M, Jover P, Arkkio A and Hyötyniemi H (2003). Numerical magnetic field analysis and signal processing for fault diagnostic of electrical machines. COMPEL Int J Comput Math Elect Eng 22(4): 969–981Finley W, Hodowanec M, Holter W (2000) An analytical approach to solving motor vibration problems. IEEE Trans Industry Appl 363(5)Cameron JR, Thomson WT, Eng C, Dow AB (1986) Vibration and current monitoring for detecting airgap eccentricity in large induction motors. IEE Proc Inst Elect Eng 133(Pt. B, No. 3)Smith AC, Dorrell DG (1996) Calculation and measurements of unbalance magnetic pull in cage induction motors with eccentric rotors. Part 1: Analytical model. IEE Proc Elect Power Appl 143(3)Dorrell DG, Smith AC (1996) Calculation and measurements of unbalance magnetic pull in cage induction motors with eccentric rotors. Part 2: Experimental investigation. IEE Proc Elect Power Appl 143(3)Dorrell DG, Thomson WT and Roach S (1997). Analysis of airgap flux, current, and vibration signals as a function of a combination of static and dynamic eccentricity in 3-phase induction motors. IEEE Trans Indus Appl 33: 24–34Verma SP, Balan A (1994) Determination of radial forces in relation to noise and vibrations problems of squirrel cage induction motors. IEEE Trans Energy Convers 9(2)Vandevelde L, Melkebeek AA (2001) Numerical analysis of vibrations of squirrel-cage induction motors based on magnetic equivalent circuits and structural finite element models. In: Industry Application Conference, 2001. Thirsty-six IAS Annual Meeting. Conference records of the 2001 IEEE, vol 4, September/October 2001, pp 2288–2295Belahcen A, Arkkio A, Klinge P, Linjama J, Voutilainen V, Westerlund J (1999) Radial forces calculation in a synchronous generator for noise analysis. In: Proceeding of the Third Chinese International Conference on Electrical Machines, August 29–31, 1999, Xi’an, China, pp 199–122Jover Rodríguez P, Belahcen A, Arkkio A (2007) Signatures of electrical faults in force distribution and vibration pattern of induction motors. IEE Proc Elect Power Appl (in press)Arkkio A (1987) Analysis of induction motor based on numerical solution of the magnetic field and circuits equations. Acta Polytechn. Scand Electri Eng Serie 59:97. Available at  Ewings DG (2000). MODAL TESTING: theory, practice and application, 2nd edn. Research studies press Ltd., BaldockDeBertoli MJ, Salon SJ, Burow DW, Slavik CJ (1993) Effects of rotor eccentricity and parallel windings on induction machine behaviour: a study using finite element analysis. IEEE Trans Magnet 29(2)Arkkio A, Antila M, Pokki K, Lanto E (2000) Electromagnetic force in a whirling cage rotor. IEE Proc Elect Power Appl 147(5

Estilo y estructura del imaginario científico de Jorge Wagensberg: semántica y entramado léxico

Este artículo viene a ser la segunda parte de nuestro estudio “La construcción lingüística de un imaginario científico”, y trata sobre los mecanismos y recursos lingüísticos más relevantes de la reciente obra científico-divulgativa del físico Jorge Wagensberg, El gozo intelectual. La determinación e interpretación de estructuras y la valoración de rasgos estilísticos peculiares, como las interrogaciones y los enunciados de carácter creativo, confirman una forma de hacer bien diferenciada en lo que respecta a la Teoría y a la Práctica. Los títulos pertenecientes a los grandes bloques de la Práctica aseguran tensión y diversidad conceptual, mientras que los títulos de los distintos capítulos se agrupan por caracteres comunes, según paradigmas temáticos, focalizaciones culturales y patrones humorísticos. La revisión del índice de conceptos nos permite diseñar una aplicación de todos aquellos términos que clarifican y ponen de manifiesto la potencia de los atractores semánticos que asientan las ideas del imaginario científico de Wagensberg.This paper further develops a previous study entitled “Linguistic construction of a scientific imagery” about Wagensberg’s scientific and literary work, and it deals with the most outstanding mechanisms and linguistic resources of his recently-published scientific and divulgative work, The Intellectual Joy. The study and interpretation of structures, as well as the evaluation of particular stylistic features, such as questions and creative statements, demonstrate very different characteristics in both parts of the book, the Theory and the Practice. The titles corresponding to the broad sections in Practice, guarantee tension and conceptual diversity, whereas the titles of the different chapters can be grouped in common characters, according to thematic paradigms, cultural focalizations and humorous patterns. A final review of the index of concepts shows the list of terms that clarify and reveal the power of semantic attractors which consolidate the ideas of Wagensberg’s scientific imagery

An approach to the Spanish consumer's perception of the sensory quality of environmentally friendly seabass

[EN] Seabass is one of the leading aquaculture species in Europe. Sensory analysis is essential for new product development. This research focused on establishing and differentiating the opinion of consumers about seabass quality obtained with organic feeding. Fish were fed for 196 days with four treatments (a control diet with 30% fishmeal and three diets with different levels of fishmeal supplemented with organic vegetable ingredients: 25%, 30% and 35%). Experimental diets were compared with commercial samples from the retail industry that were considered as "adequate quality for fish ". Two sensory analyses were carried out, check-all-that-apply (CATA) to obtain feedback on consumers' characterization towards a different type of fish evaluated and projective mapping (PM) to measure the similarity among a set of products and establish a comparison between results provided by both methods. According to the CATA results, white color, softness, meaty taste and juicy texture were considered relevant attributes, also showing a good relationship with an adequate cooked fish description. A penalty analysis confirmed that the previous characteristics were considered essential while fibrous was an undesirable attribute. The projective mapping showed a similar sensory configuration to the CATA, corroborating these findings that showed that commercial fish were placed in a position away from the rest of the treatments, and the organic diet with a higher level of fishmeal (35%) was the most distant from the control diet.This Project was subsidized by the Biodiversity Foundation 1-2020, within the framework of the Pleamar Program, co-financed by the FEMP.Calanche Morales, JB.; Tomas-Vidal, A.; Cusiyunca Phoco, ER.; Martínez-Llorens, S.; Marquina, PL.; Jover Cerda, M.; Roncales, P.... (2021). An approach to the Spanish consumer's perception of the sensory quality of environmentally friendly seabass. Foods. 10(11):1-16. https://doi.org/10.3390/foods10112694S116101

Isotopic niche partitioning in two sympatric howler monkey species

ObjectivesEcological similarity between species can lead to interspecific trophic competition. However, when ecologically similar species coexist, they may differ in foraging strategies and habitat use, which can lead to niche partitioning. As the body tissues of consumers contain a stable isotope signature that reflects the isotopic composition of their diet, stable isotope analysis is a useful tool to study feeding behavior. We measured the isotopic niche width, which is a proxy for trophic niche width, of mantled (Alouatta palliata) and black (A. pigra) howler monkeys. Specifically, studied populations in allopatry and sympatry to assess whether these species showed niche partitioning.Materials and MethodsBetween 2008 and 2012, we collected hair samples from 200 subjects (113 black and 87 mantled howler monkeys) and used continuous flow isotope ratio mass spectrometry to estimate δ13C and δ15N. We described the isotopic niche width of each species in allopatry and sympatry with the Bayesian estimation of the standard ellipse areas.ResultsIn allopatry, isotopic niche width and isotopic variation were similar in both species. In sympatry, black howler monkeys had a significantly broader isotopic niche, which was mainly determined by high δ15N values, and included the majority of mantled howler monkeys’ isotopic niche. The isotopic niche of mantled howler monkeys did not differ between sympatry and allopatry.ConclusionsThe coexistence of these ecologically similar species may be linked to trophic niche adjustments by one species, although the particular features of such adjustments (e.g., dietary, spatial, or sensory partitioning) remain to be addressed.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/155926/1/ajpa24028.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/155926/2/ajpa24028_am.pd

Diagnostic yield of early repeat colonoscopy after suboptimal bowel preparation in a fecal immunochemical test-based screening program

Background Current guidelines regarding surveillance after screening colonoscopy assume adequate bowel preparation. However, follow-up intervals after suboptimal cleansing are highly heterogeneous. We aimed to determine the diagnostic yield of early repeat colonoscopy in patients with suboptimal bowel preparation in fecal immunochemical test (FIT)-based screening colonoscopy. Methods An observational study including patients who underwent colonoscopy with suboptimal bowel preparation after positive FIT screening and then repeat colonoscopy within 1 year. Suboptimal preparation was defined as a Boston Bowel Preparation Scale (BBPS) score of 1 in any segment. Patients with a BBPS score of 0 in any segment or incomplete examination were excluded. The adenoma detection rate (ADR), advanced ADR (AADR), and colorectal cancer rate were calculated for the index and repeat colonoscopies. Results Of the 2474 patients with FIT-positive colonoscopy at our center during this period, 314 (12.7%) had suboptimal preparation. Of the 259 (82.5%) patients who underwent repeat colonoscopy, suboptimal cleansing persisted in 22 (9 %). On repeat colonoscopy, the ADR was 38.7% (95% CI 32.6% to 44.8%) and the AADR was 14.9% (95%CI 10.5% to 19.4%). The per-adenoma miss rate was 27.7% (95 %CI 24.0% to 31.6%), and the per-advanced adenoma miss rate was 17.6% (95%CI 13.3% to 22.7%). After repeat colonoscopy, the post-polypectomy surveillance recommendation changed from 10 to 3 years in 14.7% of the patients with previous 10-year surveillance recommendation. Conclusions Patients with suboptimal bowel preparation on FIT-positive colonoscopy present a high rate of advanced adenomas in repeat colonoscopy, with major changes in post-polypectomy surveillance recommendations

Modalidades productivas en el pimiento de invernadero y su incidencia en la comercialización

Se comenta, en principio, la situación económica del pimiento y cual es su posición competitiva. Actualmente la producción y comercialización de pimiento se encuentran muy condicionadas en aspectos económicos, medioambientales, y de la calidad y seguridad alimentaria, que se pueden sintetizar en: Unos costes de producción elevados; los mercados se encuentran muy abastecidos, con riesgo de saturación y descenso de los precios; dominio de la gran distribución en la comercialización; Política Agraria Comunitaria (PAC) a favor del medioambiente y de la biodiversidad; sensibilización de los consumidores por la sanidad de los productos y obligación de cumplir con la trazabilidad. Aunque España ha competido favorablemente con otros países europeos, en las producciones hortofrutícolas de invernadero, deberá en el futuro tener en cuenta a los países mediterráneos, más aún, después del Acuerdo Euromediterráneo. En el trabajo se analizan las características de la producción de pimiento en invernadero, centradas en el cultivo en sustrato, la producción integrada y la producción ecológica. Una vez efectuada la valoración económica de cada modalidad productiva, se establecen una serie de consideraciones sobre la incidencia de cada una de ellas en la comercialización

Risk Factors for Metachronous Colorectal Cancer or Advanced Adenomas After Endoscopic Resection of Highrisk Adenomas

Background & aims: Among the characteristics of high-risk adenomas (HRAs), some may predict a higher risk of metachronous advanced lesions. Our aim was to assess which HRA characteristics are associated with high risk of metachronous colorectal cancer (CRC) or advanced adenomas (AAs). Methods: We systematically searched Pubmed, EMBASE, and Cochrane for cohort studies and clinical trials of CRC or AA incidence at surveillance stratified by baseline lesion size, histology, and multiplicity. We calculated pooled relative risks (RRs) using a random-effects model. Heterogeneity was assessed with the I2 statistic. Results: Fifty-five studies were included, with 936,540 patients with mean follow-up 5.4 ± 2.9 years. CRC incidence per 1000 person-years was 2.6 (2.1-3.0) for adenomas ≥20 mm, 2.7 (2.2-3.2) for high-grade dysplasia (HGD), 2.0 (1.8-2.3) for villous component, 0.8 (0.1-1.4) for ≥5 adenomas, 1.0 (0.7-1.2) for ≥3 adenomas. Metachronous CRC risk was higher in adenomas ≥20 mm vs 10 to 19 mm (RR, 2.08; 95% confidence interval [CI], 1.20-3.61), HGD vs low-grade dysplasia (RR, 2.89; 95% CI, 1.88-4.44), villous vs tubular (RR, 1.75; 95% CI, 1.33-2.31). No significant differences in CRC risk were found in ≥3 adenomas vs 1 to 2 (RR, 1.24; 95% CI, 0.84-1.83), nor in ≥5 adenomas vs 3 to 4 (RR, 0.79; 95% CI, 0.30-2.11). Compared with normal colonoscopy, RR for CRC risk was 2.61 (95% CI, 2.06-3.32) for ≥10mm, 6.62 (95% CI, 4.60-9.52) for HGD, 3.58 (95% CI, 2.24-5.73) for villous component, and 2.03 (95% CI, 1.40-2.94) for ≥3 adenomas. Similar trends were seen for metachronous AAs. Conclusion: Metachronous CRC risk is highest in patients with baseline adenomas with ≥20 mm or HGD. Multiplicity does not seem to be associated with substantially higher CRC risk in the near term