Scientific Knowledge in Aristotle’s Biology

Aristotle was the first thinker to articulate a taxonomy of scientific knowledge, which he set out in Posterior Analytics. Furthermore, the “special sciences”, i.e., biology, zoology and the natural sciences in general, originated with Aristotle. A classical question is whether the mathematical axiomatic method proposed by Aristotle in the Analytics is independent of the special sciences. If so, Aristotle would have been unable to match the natural sciences with the scientific patterns he established in the Analytics. In this paper, I reject this pessimistic approach towards the scientific value of natural sciences. I believe that there are traces of biology in the Analytics as well as traces of the Analytics’ theory in zoological treatises. Moreover, for a lack of chronological clarity, I think it’s better to unify Aristotle’s model of scientific research, which includes Analytics and the natural sciences together

Contrasting signatures of distinct human water uses in regulated flow regimes

In the last century, about 50,000 dams have been constructed all around the world, and regulated rivers are now pervasive throughout the Earth\u2019s landscapes. Damming has produced global-scale alterations of the hydrologic cycle, inducing severe consequences on the ecological and morphological equilibrium of streams. However, a recognizable link between specific uses of reservoirs and their impact on flow regimes has not been disclosed yet. Here, extensive hydrological data are integrated with a physically-based model to investigate hydrological alterations downstream of 47 isolated dams in the Central Eastern U.S. Our results reveal a strong connection between the anthropogenic use and the hydrological impact of dams. Flood control reduces the temporal variability and spatial heterogeneity of river flows proportionally to the specific capacity allocated to mitigate floods (i.e., capacity scaled to the average inflow). Conversely, water supply increases the relative variability and regional heterogeneity of streamflows proportionally to the relative amount of withdrawn inflow. Accordingly, downstream of our multipurpose reservoirs the impact of regulation on streamflow variability is smoothed due to the compensating effect of flood control and water supply. Nevertheless, reservoirs with high storage capacity and overlapping uses produce regulated hydrographs that increase their unpredictability for larger aggregation periods and, thus, resemble an autocorrelated red noise. These findings suggest that the increase of freshwater demand could redefine the cumulative effects of dams at regional scale, reshaping the trajectories of eco-morphological alteration of dammed rivers

Statistical characterization of spatio-temporal sediment dynamics in the Venice lagoon

Characterizing the dynamics of suspended sediment is crucial when investigating the long-term evolution of tidal landscapes. Here we apply a widely tested mathematical model which describes the dynamics of cohesive and noncohesive sediments, driven by the combined effect of tidal currents and wind waves, using 1 year long time series of observed water levels and wind data from the Venice lagoon. The spatiotemporal evolution of the computed suspended sediment concentration (SSC) is analyzed on the basis of the \u201cpeak over threshold\u201d theory. Our analysis suggests that events characterized by high SSC can be modeled as a marked Poisson process over most of the lagoon. The interarrival time between two consecutive over threshold events, the intensity of peak excesses, and the duration are found to be exponentially distributed random variables over most of tidal flats. Our study suggests that intensity and duration of over threshold events are temporally correlated, while almost no correlation exists between interarrival times and both durations and intensities. The benthic vegetation colonizing the central southern part of the Venice lagoon is found to exert a crucial role on sediment dynamics: vegetation locally decreases the frequency of significant resuspension events by affecting patiotemporal patterns of SSCs also in adjacent areas. Spatial patterns of the mean interarrival of over threshold SSC events are found to be less heterogeneous than the corresponding patterns of mean interarrivals of over threshold bottom shear stress events because of the role of advection/dispersion processes in mixing suspended sediments within the lagoon. Implications for long-term morphodynamic modeling of tidal environments are discussed

A probabilistic approach to quantifying hydrologic thresholds regulating migration of adult Atlantic salmon into spawning streams

Acknowledgment Data to support this study are provided by the Marine Scotland Science Freshwater Laboratory (MSS-FL) and are available for free download on line [Glover and Malcolm, 2015a, 2015b].Peer reviewedPublisher PD

Causa e princípio explicativo do ser em Aristóteles (Metafísica VII, 17)

The main topic of this paper is to study the role the form has in constituting composite substances. I will examine the chapter 17 of Metaphysics VII, especially the lines 1041b12-25, who Aristotle uses the example of syllable to show that form is the primary cause of being of sensible substances in that it causes them to be one. The main issue of this investigation is to show that, especially in the last chapter of Metaphysics Zeta, essence is closely identified by Aristotle to the form, which is in charge to transform the material elements into an essential unity and to explain the structure of hylomorphic substances.L’obbiettivo principale di questo articolo è studiare il ruolo rivestito dalla forma come causa costitutiva delle sostanze composte. Esaminerò il capitolo 17 del libro VII della Metafisica, in particolare le linee 1041b12-25, in cui Aristotele usa ’esempio della sillaba per mostrare che la forma è la causa prima dell’essere delle sostanze sensibili in quanto causa del loro formare una unità. Il punto culminante della ricerca è il tentativo di mostrare, specialmente nell’ultimo capitolo del livro in questione, che l’essenza è identificata con la forma, la quale trasforma gli elementi materiali in una unità essenziale e di spiegare la struttura hilemorfica delle sostanze.O artigo tem como objetivo realizar uma análise acerca da função da causa formal na constituição das substâncias compostas. Para tanto, analiso o capítulo 17 do Livro VII da Metafísica, especialmente as linhas 1041b 12-25, nas quais Aristóteles utiliza o exemplo da sílaba para se aproximar da definição da forma como causa primeira do ser. O principal resultado desta investigação é mostrar que, no capítulo final do livro Zeta da Metafísica, Aristóteles entende a forma como a causa da transformação do conjunto material numa unidade substancial e como princípio de explicação dos compostos hilemórficos

Hydrological controls on river network connectivity

This study proposes a probabilistic approach for the quantitative assessment of reach- and network-scale hydrological connectivity as dictated by river flow space–time variability. Spatial dynamics of daily streamflows are estimated based on climatic and morphological features of the contributing catchment, integrating a physically based approach that accounts for the stochasticity of rainfall with a water balance framework and a geomorphic recession flow analysis. Ecologically meaningful minimum stage thresholds are used to evaluate the connectivity of individual stream reaches, and other relevant network-scale connectivity metrics. The framework allows a quantitative description of the main hydrological causes and the ecological consequences of water depth dynamics experienced by river networks. The analysis shows that the spatial variability of local-scale hydrological connectivity is strongly affected by the spatial and temporal distribution of climatic variables. Depending on the underlying climatic settings and the critical stage threshold, loss of connectivity can be observed in the headwaters or along the main channel, thereby originating a fragmented river network. The proposed approach provides important clues for understanding the effect of climate on the ecological function of river corridors

Dynamic Subchondral Bone Changes in Murine Models of Osteoarthritis

‘Arthritis’ is a generic term which includes many different rheumatic disease types, all of which are connected with impaired functioning of joints. Osteoarthritis (OA) is the most common form of arthritis, and the leading cause of chronic disability in the Western world. In OA normal functioning of a joint becomes impaired. Movement of the joint is painful and limited, and in advanced disease stages patients may complain of nocturnal or permanent pain. In a diarthrodial joint, the ends of two bones meet, marked by a bony end plate called the subchondral bone plate. To provide frictionless movement, the subchondral bone plate is covered with a smooth surface of articular cartilage. Cartilage also acts as a shock absorber of mechanical forces and distributes the stresses more evenly on the underlying tissues. For joint lubrication, lubricin and hyaluronic acid are produced by the synovium and by the superficial layer of the articular cartilage. Menisci, tendons and ligaments firmly hold the two bones in place, and the surrounding musculature ensures that the bones are able to move with respect to each other. These latter structures also play an important role in shock absorption to protect the joint from excessive mechanical forces