Tema 2. Dinàmica d'una partícula : Estudi dels efectes que produeixen el moviment

2022/20231r quadrimestr

Organització espacial i temporal de la pluja a l'àrea metropolitana de Barcelona

In order to avoid the catastrophes caused by intense or even moderately intense, rainfall episodes, it is essential to have as exhaustive a knowledge as possible of the behaviour of the same. We have a source of information to study these behaviours with the data provided by rain gauges. Our work is based on data obtained from the dense network of rain gauges that the companies CLABSA / BCASA have been managing in the metropolitan area of Barcelona. Chronological series of rainfall data from 1994 to 2019, over 25 years, are currently available. This means that the results obtained with them are beginning to have climatic significance and statistical robustness. With this information we have done three types of studies, temporal, spatial and kinematic. With the first two we have completed and updated previous studies with more data, while the kinematic studies are the first to be obtained in the Barcelona area. Temporality studies are made by obtaining the intensity-duration-frequency (IDF) curves where we present the rainfall intensity as a function of its duration for different return periods. We do this individually for each of the stations in the network as well as for certain groupings of them, for example maximum value groupings. In all cases we can say that the results obtained are compatible and complement the results obtained previously with less data. Having the data from a network of rain gauges allows, among other things, to study the spatial structure of storms. In relation to this study we have calculated the number of independent stations which are equivalent to the network for the different rainfall durations. It is seen that this number is a value that decreases exponentially with the duration of the storms towards the value 1 (an independent station) and that for short durations five independent stations are enough to represent the urban network . We have designed a network of points, with a spacing of 300 m between them, so that with the Barnes interpolation method we assign to each of them a precipitation value. Using the experimental data of the stations we have studied the areal reduction factors (ARF) which should also allow us to obtain estimates of precipitation in a given area as a function of its value at a point. These calculations are again fundamentally compatible with the results obtained previously. We continue our work, taking advantage again that we have data from the network of rain gauges, with a study of the kinematics of rainfall. We assume that the storms are endowed with a constant speed and that the different properties studied, such as the "beginning of the rain" or the "first maximum intensity", have the same speed. The results indicate that not all the properties studied have exactly the same speed and to think that a rain has a constant speed is only an approximation. We end our work by extrapolating the temporary study methods to the data provided by different climate models applied in the Barcelona area and for the 21st century. These models provide data for daily time intervals, and we used downscaling techniques to obtain sub-daily time estimates so that we were able to perform a complete IDF time study.Per evitar les catàstrofes ocasionades per les pluges intenses, o fins i tot moderadament intenses, és imprescindible tenir un coneixement, tan exhaustiu com sigui possible, del comportament de les mateixes. Una font d'informació, per poder fer els estudis d'aquests comportaments, la tenim amb les dades que ens proporcionen els pluviòmetres. El nostre treball es fonamenta en les dades obtingudes de la xarxa densa de pluviòmetres que les empreses CLABSA i BCASA han estat gestionant a la zona metropolitana de Barcelona. Actualment disposem de series cronològiques de dades pluviomètriques des del 1994 fins el 2019, una mica més de 25 anys, que suposa que els resultats obtinguts amb les mateixes comencen a tenir significació climàtica i robustesa estadística. Amb aquestes informacions hem fet tres tipus d'estudis, temporals, espacials i cinemàtics. Amb els dos primers hem completat estudis anteriors amb més dades i els estudis cinemàtics són els primers que s'han obtingut per l'àrea barcelonina. Els estudis de temporalitat es fan amb l’obtenció de les corbes d’intensitat-duració-freqüència (IDF) on presentem la intensitat de la pluja en funció de la duració de la mateixa per diferents períodes de retorn. Això ho fem individualment per cadascuna de les estacions de la xarxa així com per determinades agrupacions de les mateixes, per exemple agrupacions de valor màxim. En tots els casos podem afirmar que els resultats obtinguts són compatibles i complementen els resultats obtinguts amb anterioritat amb menys quantitat de dades. Disposar de les dades d’una xarxa de pluviòmetres permet, entre d'altres coses, estudiar l'estructura espacial de les tempestes. En relació amb aquest estudi hem calculat el nombre d'estacions independents i equivalents a la xarxa per les diferents durades de les pluges. Es veu que és un valor que decreix exponencialment amb la durada de les tempestes cap al valor 1 (una estació independent) i que per durades curtes es tenen cinc estacions independents. Hem dissenyat una xarxa de punts, amb un espaiat de 300 m entre ells, de forma que amb el mètode d’interpolació de Barnes assignem a cadascun d'ells un valor de precipitació. Fent ús de les dades experimentals de les estacions hem estudiat els factors de reducció areal (areal reduction factors: ARF) que també ens ha de permetre obtenir estimacions de la precipitació a una determinada zona en funció del valor de la mateixa a un punt. Aquests càlculs tornen a ser fonamentalment compatibles amb els resultats obtinguts amb anterioritat. Continuem el nostre treball, aprofitant de nou que tenim dades de la xarxa de pluviòmetres, amb un estudi de la cinemàtica de les tempestes. Suposem que les tempestes estan dotades d'una velocitat constant i que les diferents propietats estudiades, com per exemple el “començament de la pluja” o el “primer màxim d'intensitat”, tenen aquesta mateixa velocitat. Els resultats ens indiquen que no totes les propietats estudiades tenen exactament la mateixa velocitat i pensar que una pluja presenta una velocitat constant és només una aproximació. Finalitzem el nostre treball extrapolant els mètodes d'estudi temporals a les dades proporcionades per diferents models climàtics, aplicats a la zona barcelonina i pel segle XXI. Aquests models proporcionen dades per intervals temporals diaris i hem fet ús de tècniques de downscaling per obtenir estimacions temporals sots-diàries de forma que hem pogut fer un estudi temporal de les IDF complet.Postprint (published version

A single scaling parameter as a first approximation to describe the rainfall pattern of a place: application on Catalonia

As well as in other natural processes, it has been frequently observed that the phenomenon arising from the rainfall generation process presents fractal self-similarity of statistical type, and thus, rainfall series generally show scaling properties. Based on this fact, there is a methodology, simple scaling, which is used quite broadly to find or reproduce the intensity–duration–frequency curves of a place. In the present work, the relationship of the simple scaling parameter with the characteristic rainfall pattern of the area of study has been investigated. The calculation of this scaling parameter has been performed from 147 daily rainfall selected series covering the temporal period between 1883 and 2016 over the Catalonian territory (Spain) and its nearby surroundings, and a discussion about the relationship between the scaling parameter spatial distribution and rainfall pattern, as well as about trends of this scaling parameter over the past decades possibly due to climate change, has been presented.Peer ReviewedPostprint (author's final draft

Rainfall spatial organization and areal reduction factors in the metropolitan area of Barcelona (Spain)

The rainfall spatial organization in the metropolitan area of Barcelona (Spain) has been studied from records of an urban rain gauge network in the period 1994–2009. Using statistical and regional analysis techniques, correlation between data recorded by the different rain gauges has been calculated, and the effective number of independent stations (neq) equivalent to the used network has been determined. It has been found out that for durations longer than 20 min, the areal rainfall return period observed for a storm registered by the network approximately decreases by a factor of 1/neq in relation to the current point rainfall intensity–duration–frequency relationships for the metropolitan area of Barcelona. Using objective analysis techniques, continuous precipitation fields have been generated on a regular grid with a spatial resolution of 300×300 m for the storms registered by the rain gauges from 1994 to 2009, for durations from 10 min to 24 h. The precipitation fields obtained have been useful to estimate the characteristic areal reduction factors in the metropolitan area of Barcelona. A direct relationship has been found between the areal reduction factor for all the area corresponding to the urban rainfall network of Barcelona and the effective number of neq for every duration consideredPostprint (published version

A simple scaling analysis of rainfall in Andalusia (Spain) under different precipitation regimes

A simple scaling analysis was performed in Andalusia (Spain) using daily records from 377 selected stations covering the temporal period between 1870 and 2018. Since Andalusia is a region of considerable climatic variety, with notably wet areas as well as extremely dry zones, this study is useful to investigate the relationship between the simple scaling parameter value and the characteristic rainfall regime of a place. Despite the great correspondence with the average annual precipitation (PRCPTOT), a clear dependence on rainfall irregularity was observed, revealed by the ratio of the maximum daily precipitation and PRCPTOT, as well the wet spells frequency index CWD. The spatial distribution of the simple scaling parameter captured the increasing influence of the Mediterranean Sea towards the East. The easternmost dry areas are clearly influenced by Mediterranean disturbances, with a high proportion of convective rainfall and an irregular rainfall pattern. Using a simple scaling parameter, the generalized equations of the intensity-duration-frequency (IDF) curves, of great hydrological interest were calculated for the eight Andalusian provincial capitals. Moreover, the temporal trends of this parameter in the four past decades were studied in the different areas with the aim of determining if changes in their rainfall patterns due to global warming could be detected.Peer ReviewedPostprint (published version

Análisis de escala simple de veinticinco años de registros de la red pluviométrica de Barcelona

El área metropolitana de Barcelona, de aproximadamente 100 Km2 de extensión, dispone de una red densa de pluviómetros de balancín que se empezó a instalar en 1983, y ha ido siendo gestionada desde entonces por diferentes empresas (CLABSA, Aqualogy, y actualmente BCASA). Se dispone de los registros 5-minutales de lluvia de una veintena de pluviómetros, a lo largo de 25 años de funcionamiento desde 1994 hasta 2019. A partir de estos registros de lluvia ha sido posible realizar un análisis de escala simple específico para cada pluviómetro, con el fin de poner de manifiesto las características, ligeramente diferentes, de la precipitación recogida en cada una de las zonas del área urbana.Peer ReviewedPostprint (published version

Population-based sequencing of Mycobacterium tuberculosis reveals how current population dynamics are shaped by past epidemics

23 páginas, 4 figuras, 1 tabla.Transmission is a driver of tuberculosis (TB) epidemics in high-burden regions, with assumed negligible impact in low-burden areas. However, we still lack a full characterization of transmission dynamics in settings with similar and different burdens. Genomic epidemiology can greatly help to quantify transmission, but the lack of whole genome sequencing population-based studies has hampered its application. Here, we generate a population-based dataset from Valencia region and compare it with available datasets from different TB-burden settings to reveal transmission dynamics heterogeneity and its public health implications. We sequenced the whole genome of 785 Mycobacterium tuberculosis strains and linked genomes to patient epidemiological data. We use a pairwise distance clustering approach and phylodynamic methods to characterize transmission events over the last 150 years, in different TB-burden regions. Our results underscore significant differences in transmission between low-burden TB settings, i.e., clustering in Valencia region is higher (47.4%) than in Oxfordshire (27%), and similar to a high-burden area as Malawi (49.8%). By modeling times of the transmission links, we observed that settings with high transmission rate are associated with decades of uninterrupted transmission, irrespective of burden. Together, our results reveal that burden and transmission are not necessarily linked due to the role of past epidemics in the ongoing TB incidence, and highlight the need for in-depth characterization of transmission dynamics and specifically tailored TB control strategies.European Research Council 638553-TB-ACCELERATE; European Research Council 101001038-TBRECONNECT; Ministerio de Ciencia e Innovación SAF2016-77346-RPeer reviewe

Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat

Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat