Stream biofilm response to an increasing number of non-flow periods

Anthropogenic impacts and climate change are considerably altering freshwater systems. Most significant consequences of this are changes to flow regimes as well as the transformation of permanent into temporary waterways. This is problematic, as despite their role in supporting biodiversity and ecosystem processes, temporary waterways are undervalued and poorly understood. In fact, although the effects of non-flow periods are known, there is a lack of knowledge regarding how changes in frequency and duration of non-flow periods influence temporary waterways. Therefore, the goal of further research is to extend the current knowledge surrounding the effects of temporal components on the aquatic ecosystem. This bachelor thesis aims to identify how the frequency of non-flow periods affects autotrophic and heterotrophic stream biofilm. With this objective, an experiment at the Experimental Stream Facility of Catalan Institute for Water Research (ICRA) was performed. The treatments consisted of one drought duration (28 days) and three frequencies (1 period of 28, 2 periods of 14, 4 periods of 7 non-flow days). The development of the autotrophic and heterotrophic stream biofilm was measured during flow periods by means of yield of photochemistry, aerobic respiration, ecosystem metabolism and ash free dry mass. The hypotheses were that with increasing frequency, the effects on stream biofilm are less because the number of subsequent non-flow days is smaller and thus the biofilm is less stressed, and that autotrophs in the epipsammic biofilm recover more slowly than in the epilithic biofilm, because the amount of water retained in sand is higher. Both hypotheses were partially confirmed, as an increasing frequency only lessened the effect on epipsammic biofilm and only autotrophic function recovered more slowly in sand than on cobbles. In addition, the majority of the variables experienced the most severe impact and thus the quickest recovery in the same treatment. Nevertheless, at the end of the experiment none of the differences persisted. Therefore, the frequency of non-flow periods only had an effect on a short-term but not on a long-term scale and consequently, both hypotheses were discarded

Process, System, Causality, and Quantum Mechanics, A Psychoanalysis of Animal Faith

We shall argue in this paper that a central piece of modern physics does not really belong to physics at all but to elementary probability theory. Given a joint probability distribution J on a set of random variables containing x and y, define a link between x and y to be the condition x=y on J. Define the {\it state} D of a link x=y as the joint probability distribution matrix on x and y without the link. The two core laws of quantum mechanics are the Born probability rule, and the unitary dynamical law whose best known form is the Schrodinger's equation. Von Neumann formulated these two laws in the language of Hilbert space as prob(P) = trace(PD) and D'T = TD respectively, where P is a projection, D and D' are (von Neumann) density matrices, and T is a unitary transformation. We'll see that if we regard link states as density matrices, the algebraic forms of these two core laws occur as completely general theorems about links. When we extend probability theory by allowing cases to count negatively, we find that the Hilbert space framework of quantum mechanics proper emerges from the assumption that all D's are symmetrical in rows and columns. On the other hand, Markovian systems emerge when we assume that one of every linked variable pair has a uniform probability distribution. By representing quantum and Markovian structure in this way, we see clearly both how they differ, and also how they can coexist in natural harmony with each other, as they must in quantum measurement, which we'll examine in some detail. Looking beyond quantum mechanics, we see how both structures have their special places in a much larger continuum of formal systems that we have yet to look for in nature.Comment: LaTex, 86 page

A composite leading indicator for the Peruvian economy based on the BCRP's monthly business tendency surveys

This paper documents the construction of a composite leading indicator for the Peruvian economy based on the business tendency surveys (BTS) conducted by the Banco Central de Reserva del Perú (BCRP). We first classify potential composite leading indicators into "semantic" and "sophisti-cated" types. The former are based on the contents of the underlying indicators, whereas the latter results from statistical analyses relating to pre-determined reference series. We show that the BCRP BTS data provides a suitable basis for the construction of a sophisticated indicator with the Peru-vian year-on-year GDP growth rate as a reference series. The indicator selection consists of a num-ber of steps comprising semantic analyses of the questionnaire items, cross-correlation analyses as well as turning point analyses. We argue that based on these analyses, the choice should fall on five indicators, relating to firm-specific questionnaire items as well as to items relating to the sector or economy as a whole. The composite leading indicator is computed as the fist principal component of the selected variables. In-sample, it shows a lead of four months before the reference series, which amounts to about six months before the first official data release dates. Due to the limited number of observations (the BCRP's BTS now covering about eight years), we did not reserve any data points for out-of-sample analyses of the suggested composite leading indicator. Accordingly, the performance of the indicator still has to stand the test of time and its lead should be carefully monitored.

Why Would the Rise of Social Media Increase the Influence of Traditional Media on Collective Judgments?

3reservedrestrictedRavasi, Davide; Etter, Michael; Colleoni, ElanorRavasi, Davide; Etter, Michael; Colleoni, Elano

An investigation of tandem row high head pump inducers Interim report

Streamline calculations for tandem row high head pump inducer