Impacts of clear-cutting on groundwater discharge rates into a boreal stream

Treballs Finals de Grau de Física, Facultat de Física, Universitat de Barcelona, Curs: 2022, Tutora: Carolina OlidClear-cutting is one of the major disturbances impacting forest carbon (C) storage by increasing dissolved C in soils that can be easily transported through groundwater and processed in recipient waters such as lakes and streams. Forest clear-cutting has been found to increase concentrations of greenhouse gases (GHGs) (carbon dioxide (CO2) and methane (CH4)) in first-order boreal streams. However, the importance of groundwater inflows in controlling stream GHG budgets is still uncertain. Here we combined a catchment experiment and the use of natural tracers (i.e., radon (222Rn)) to quantify the impact of forest clear-cuts and buffer zones on groundwater inflow rates into streams. Analyses of 222Rn concentrations in stream and groundwater, collected between April and October before and after clear-cut (2020 and 2021, respectively), showed that clear-cut increased groundwater discharge rates to the stream, resulting in higher inputs of dissolved C which likely increase GHG emissions to the atmosphere. Uncertainties in the results associated with the method’s limitations are also discusse

An Assessment on the Requirements for Deep Space Optical Communications

Over the last decade, terms such as big data and IoT have become part of our everyday vocabulary, and as time goes by, more and more systems are collecting larger amounts of data in order to provide new services or improve quality, and aerospace sector is not an exception. Space probes and rovers, which originally communicated with ground stations using S-band, have moved to higher frequencies in order to be able to transmit more information per unit of time. As the frequency of the system increases, the optical band is reached, 40 years ago, the first experiment in aerospace to demonstrate laser communication, the Airbone Flight Test System (AFTS), was conducted. Numerous efforts have been made to demonstrate that optical communications are possible. When sending an exploration mission, the scientific community maximises the performance of the instruments by taking into account multiple criteria, such as whether the particular device has been previously tested in space and the likelihood of failure. Therefore, the use of new technologies requires a process of multiple demonstration missions prior to be accepted. This thesis compiles the state of the art, i.e. the knowledge acquired over the last four decades, and covers three main points: ground infrastructures, the flight terminal and the method of communication between both systems. In the first point, the study focuses on explaining the parameters that must be taken into account when designing an international ground station network, equivalent to its counterpart in the RF band, NASA’s DSN networks or ESA’s ESTRACK, among others. One of the most relevant variables that determines the location of a ground stations are the atmospheric conditions. For this reason, a series of files containing information about the planet’s atmosphere has been downloaded and processed from NASA’s LAADS DAAC database. Secondly, the link equation of a signal emitted in optical band has been studied. Each of the terms that make up the equation are presented in detail in several sections, in particular the obscuration losses in Cassegrain type antennas, the pointing losses and those due to atmospheric absorption and turbulence. Finally, two practical studies have been carried out in which it is possible to see how the mathematics described in the previous chapters have been applied to execute missions whose purpose is to communicate in deep space. To achieve this, the JPL library and toolkit called SPICE has been used in a fictitious but realistic Mars-Earth downlink mission. Thanks to the high reliability of SPICE, all the data related to the orbital mechanics of a space mission has been obtained and compared, in order of magnitude, with a mission called Psyche and DSOC, scheduled for launch in August 2022. Apart from didactically exemplifying the terms of the link equation in a specific mission, key elements such as capacity or bit rate have also been retrieved, which allow immediate conclusions to be drawn in favour of this technology and thus contribute to its consolidation in the field of deep space communications

A new fairy shrimp Phallocryptus tserensodnomi (Branchiopoda: Anostraca) from Mongolia

13 páginas, 6 figuras.A new species of Phallocryptus Biraben 1951 (Branchiopoda, Anostraca) from Mongolia is described. Phallocryptus tserensodnomi sp. nov. is close to P. spinosa (Milne-Edwards 1840), but both morphological and molecular analyses (Cytochrome Oxidase I, COI) indicate that they represent separate species. Most relevant differential features of the new species include: (1) frontal appendage provided with small ventral conical outgrowths; (2) second antennamere evenly curved, sickle-shaped; (3) distal fleshy process on labrum evenly curved forwards and tapering; (4) short stout acute spine-like projections present at each side of basal portion of gonopods; (5) female second antennae shorter and wider than in P. spinosa, tapering. Based on morphological comparisons the new species appears to be a Mongolian endemic, although some genotypes of presumed P. spinosa from Africa are similar to the new species, suggesting P. tserensodnomi might have a wider distribution.The study has been supported by the Program for Biodiversity Conservation of ENDESA (Empresa Nacional de Electricidad S.A.) and by the Spanish Government projects Fundalzoo (CGL2010-14841) and Invasivefish (427/ 2011).Peer reviewe

Collembola’s role in regulating mass fluxes in soil and the effects of contrasting life histories

The study determined metabolic rates and elemental pools for two Collembola species with contrasting life histories. The fittest of the two species, P. minuta, excreted the equivalent of 10–12% of the elemental body content per day, and P. armata 7–10%. Most elements are lost to excretion (CO2 and N-waste). These figures in combination with stoichiometry and life histories indicate that the cost of P. minuta’s better fitness is a requirement for a higher quality diet than P. armata. The data produced in this study can be used to estimate the collembolan contribution to C and N fluxes in the soil

Nutrient allocations and metabolism in two collembolans with contrasting reproduction and growth strategies

Physiological mechanisms such as allocation and release of nutrients are keys to understanding an animal\u27s adaptation to a particular habitat. This study investigated how two detrivores with contrasting life‐history traits allocated carbon (C) and nitrogen (N) to growth, reproduction and metabolism. As model organisms we used the collembolans, Proisotoma minuta (Tullberg 1871) and Protaphorura fimata (Gisin 1952). To estimate allocations of C and N in tissue, we changed the isotopic composition of the animal\u27s yeast diets when they became sexually mature and followed isotope turnover in tissue, growth and reproduction for 28 days. In addition, we measured the composition of C, N and phosphorus (P) to gain complementary information on the stoichiometry underlying life‐history traits and nutrient allocation. For P. minuta, the smallest and most fecund of the two species, the tissue turnover of C and N were 13% and 11% day−1, respectively. For P. fimata, the equivalent rates were 5% and 4% d−1, respectively. Protaphorura fimata had the lowest metabolic rate relative to total body mass but the highest metabolic rates relative to reproductive investment. Adult P. fimata retained approximately 17% of the nutrient reserves acquired while a juvenile and adult P. minuta about 11%. N and P contents of total tissue were significantly higher in P. minuta than in P. fimata, suggesting that tissue turnover was correlated with high protein‐N and RNA‐P. Our results suggest that the lower metabolism and nutritional requirements by P. fimata than P. minuta is an adaptation to the generally low availability and quality of food in its natural habitat. The methodological approach we implemented tracking mass balance, isotope turnover and elemental composition is promising for linking nutrient budgets and life‐history traits in small invertebrates such as Collembola

Conservation of the endemic Pyrenean newt (Calotriton asper) in the age of invasive species: interlake dispersal and colonisation dynamics

info:eu-repo/semantics/publishedVersio

Optimal patchings for consecutive ones matrices

AbstractWe study a variant of the weighted consecutive ones property problem. Here, a 0/1-matrix is given with a cost associated to each of its entries and one has to find a minimum cost set of zero entries to be turned to ones in order to make the matrix have the consecutive ones property for rows. We investigate polyhedral and combinatorial properties of the problem and we exploit them in a branch-and-cut algorithm. In particular, we devise preprocessing rules and investigate variants of "local cuts". We test the resulting algorithm on a number of instances, and we report on these computational experiments

Relación entre estilos de pensamiento y estrategias de evitación de los estudiantes de psicología

Quinzenes Jornades de Foment de la Investigació de la FCHS (Any 2009-2010

Jocs cooperatius i problemes de bancarrota

Treballs Finals de Grau de Matemàtiques, Facultat de Matemàtiques, Universitat de Barcelona, Any: 2019, Director: Pere Calleja i Josep Vives i Santa Eulàlia[en] Cooperative game theory is the study of mathematical models of cooperation, in transferable utility games the players face the challenge to split up some good among them using cooperation. This essay is an introduction to the existing link between cooperative game theory and the so called rationing problems or bankruptcy problems. This problem is based in using division rules to allocate a quantity of good among some creditors taking into account that the sum of the claims exceeds the quantity available to allocate. We will prove that the Shapley value (Shapley 1953) and the Nucleous (Schmeidler 1969) of the cooperative game associated to the bankruptcy problem corresponds to the random arrival rule (O’Neill 1982) and the Talmud rule (Aumann and Maschler 1985) of the bankruptcy problem respectively