Household level effects of flooding : evidence from Thailand

Treball fi de màster de: Master's Degree in Specialized Economic AnalysisDirectors: Fernando Broner, Antonio CicconeThis thesis studies the impacts of flooding on income and expenditures of rural households in northeast Thailand. It explores and compares shock coping strategies and identifies household level differences in flood resilience. Drawing on unique household panel data collected between 2007 and 2016, we exploit random spatio-temporal variation in flood intensities on the village level to identify the causal impacts of flooding on households. Two objective measures for flood intensities are derived from satellite data and employed in the analysis. Both proposed measures rely on the percentage area inundated in the surrounding of a village, but the second measure is standardized and expressed in comparison to the median village level flood exposure. We find that household incomes are negatively affected by floods. However, our results suggest that rather than absolute levels of flooding, deviations from median flood exposure are driving negative effects on households. This indicates a certain degree of adaptation to floods. Household expenditures for health and especially food rise in the aftermath of flooding. Lastly, we find that above primary school education helps to completely offset potential negative effects of flooding.La presente tesis analiza el impacto de las inundaciones sobre el ingreso y consumo de los hogares rurales del noreste de Tailandia. El estudio, además, explora y compara las estrategias de adaptación e identifica diferencias en la resistencia a las inundaciones entre las familias. A partir de datos de panel sobre hogares obtenidos entre 2007 y 2016 exploramos variaciones espacio-temporales y aleatorias en la intensidad de las inundaciones a nivel de aldeas para así identificar el impacto causal de las inundaciones sobre los hogares. Para determinar la intensidad de las inundaciones, se desarrollan dos medidas objetivas a partir de datos satélite. Las dos medidas se basan en el porcentaje de área inundada en los alrededores de las aldeas, no obstante, la segunda medida se estandariza y expresa en comparación a la exposición mediana de cada aldea. Encontramos que el ingreso de las familias se ve afectado negativamente por las inundaciones, no obstante, los resultados sugieren que el determinante de los efectos negativos sobre los hogares no es el nivel absoluto de las inundaciones sino la desviación del nivel de inundaciones respecto a la mediana. Esto indica que existe un cierto grado de adaptación a las inundaciones recurrentes. En su lugar, el consumo de las familias en salud y alimentación aumentan una vez se han producido las inundaciones. Finalmente, encontramos que un nivel educativo superior a la educación primaria ayuda a compensar los potenciales efectos negativos de las inundaciones

PUBLISHER CORRECTION: LABEL-FREE FIBER-OPTIC SPHERICAL TIP BIOSENSOR TO ENABLE PICOMOLAR-LEVEL DETECTION OF CD44 PROTEIN

Increased level of CD44 protein in serum is observed in several cancers and is associated with tumor burden and metastasis. Current clinically used detection methods of this protein are time-consuming and use labeled reagents for analysis. Therefore exploring new label-free and fast methods for its quantification including its detection in situ is of importance. This study reports the first optical fiber biosensor for CD44 protein detection, based on a spherical fiber optic tip device. The sensor is easily fabricated from an inexpensive material (single-mode fiber widely used in telecommunication) in a fast and robust manner through a CO2 laser splicer..

OPTICAL FIBER BALL RESONATOR SENSOR SPECTRAL INTERROGATION THROUGH UNDERSAMPLED KLT: APPLICATION TO REFRACTIVE INDEX SENSING AND CANCER BIOMARKER BIOSENSING

Abstract: Optical fiber ball resonators based on single-mode fibers in the infrared range are an emerging technology for refractive index sensing and biosensing. These devices are easy and rapid to fabricate using a CO2 laser splicer and yield a very low finesse reflection spectrum with a quasi-random pattern. In addition, they can be functionalized for biosensing by using a thinfilm sputtering method. A common problem of this type of device is that the spectral response is substantially unknown, and poorly correlated with the size and shape of the spherical device. In this work, we propose a detection method based on Karhunen−Loeve transform (KLT), applied to the undersampled spectrum measured by an optical backscatter reflectometer. We show that this method correctly detects the response of the ball resonator in any working condition, without prior knowledge of the sensor under interrogation. First, this method for refractive index sensing of a gold-coated resonator is applied, showing 1594 RIU−1 sensitivity; then, this concept is extended to a biofunctionalized ball resonator, detecting CD44 cancer biomarker concentration with a picomolarlevel limit of detection (19.7 pM) and high specificity (30–41%). Keywords: optical fiber biosensor; optical fiber sensor; ball resonator; optical fiber spherical tip; digital signal processing; Karhunen−Loeve transform (KLT); cancer biomarker diagnosti

LABEL-FREE FIBER-OPTIC SPHERICAL TIP BIOSENSOR TO ENABLE PICOMOLAR-LEVEL DETECTION OF CD44 PROTEIN

Increased level of CD44 protein in serum is observed in several cancers and is associated with tumor burden and metastasis. Current clinically used detection methods of this protein are time-consuming and use labeled reagents for analysis. Therefore exploring new label-free and fast methods for its quantification including its detection in situ is of importance. This study reports the first optical fiber biosensor for CD44 protein detection, based on a spherical fiber optic tip device. The sensor is easily fabricated from an inexpensive material (single-mode fiber widely used in telecommunication) in a fast and robust manner through a CO2 laser splicer. The fabricated sensor responded to refractive index change with a sensitivity of 95.76 dB/RIU. The spherical tip was further functionalized with anti-CD44 antibodies to develop a biosensor and each step of functionalization was verified by an atomic force microscope. The biosensor detected a target of interest with an achieved limit of detection of 17 pM with only minor signal change to two control proteins. Most importantly, concentrations tested in this work are very broad and are within the clinically relevant concentration range. Moreover, the configuration of the proposed biosensor allows its potential incorporation into an in situ system for quantitative detection of this biomarker in a clinical setting