5,096 research outputs found
Influence of Urban Areas on Surface Water Loss in the Contiguous United States
Urbanization is one of the main drivers of surface water loss, which implies a transition from water to land. However, it is still unclear how urban areas affect the spatial pattern of surface water loss. Here, we use remotely sensed data to analyze and model the decrease of surface water extent and, in particular, the frequency of surface water loss as a function of distance from urban areas across the contiguous United States (CONUS). We employ an exponential distance-decay model that confirms the presence of a higher frequency of surface water loss in the proximity of human settlements and provides innovative insights on surface water loss patterns at different spatial scales (i.e., river basins, water resource regions, and the CONUS). These spatial patterns are found to be influenced by climatic conditions, with more widely distributed losses in arid regions with respect to temperate and continental climates. Our results provide a new and deeper understanding of the spatial influence of urban areas on surface water loss, which could be effectively integrated in the definition of sustainable strategies for urbanization, water management, and surface water restoration, focused on both human and environmental water needs
stochastic rainfall analysis for storm tank performance evaluation
Abstract. Stormwater detention tanks are widely used for mitigating impacts of combined sewer overflows (CSO) from urban catchments into receiving water bodies. The optimal size of detention tanks depends on climate and sewer system behaviours and can be estimated by using derived distribution approaches. They are based on using a stochastic model to fit the statistical pattern of observed rainfall records and a urban hydrology model to transform rainfall in sewer discharge. A key issue is the identification of the optimal structure of the stochastic rainfall model. Point processes are frequently applied, where rainfall events are schematised through the occurrence of rectangular pulses, which are governed by rainfall descriptors. In the presented model these latter descriptors are the interevent time (duration of the dry period between consecutive storms), event rainfall depth and event rainfall duration. This paper focuses on the analytical derivation of the probability distribution of the number and volume of overflows from the storm tank to the receiving water body for different and non-standard shapes of the probability distribution for above mentioned descriptors. The proposed approach is applied to 2 different sites in Spain: Valencia and Santander, located on the Mediterranean and northern Atlantic coastline, respectively. For both cases, it turned out that Pareto and Gamma-2 probability distributions for rainfall depth and duration provided a better fit than the exponential model, widely used in previous studies. A comparison between the two climatic zones, humid and semiarid, respectively, proves the key role played by climatic conditions for storm detention tanks sizing
Error-correcting code on a cactus: a solvable model
An exact solution to a family of parity check error-correcting codes is
provided by mapping the problem onto a Husimi cactus. The solution obtained in
the thermodynamic limit recovers the replica symmetric theory results and
provides a very good approximation to finite systems of moderate size. The
probability propagation decoding algorithm emerges naturally from the analysis.
A phase transition between decoding success and failure phases is found to
coincide with an information-theoretic upper bound. The method is employed to
compare Gallager and MN codes.Comment: 7 pages, 3 figures, with minor correction
Dynamic Stresses of Lactic Acid Bacteria Associated to Fermentation Processes
Despite their negligible mass the microbial agents, starters and non starters, play a profound role in the characterization of the fermented foods in terms of chemical and sensorial properties. In fact, fermented foods may be defined as foods processed through the activity of microorganisms. Fermentation processes take a special place in the evolution of human cuisine, by altering the taste experience of food products, as well as extending the storage period. In particular, foods fermented with lactic acid bacteria (LAB) have constituted an important part of human diet and of fermentation processes (involving various foods, including milk, meat, vegetables and fruits) since ancient times. They have played an essential role in the preservation of agricultural resources and in the improvement of nutritional and organoleptic properties of human foods and animal feed. Moreover, these organisms nowadays are increasingly used as health promoting probiotics, enzyme and metabolite factories and vaccine delivery vehicles
Fresh-Register Automata
What is a basic automata-theoretic model of computation with names and fresh-name generation? We introduce Fresh-Register Automata (FRA), a new class of automata which operate on an infinite alphabet of names and use a finite number of registers to store fresh names, and to compare incoming names with previously stored ones. These finite machines extend Kaminski and Francez’s Finite-Memory Automata by being able to recognise globally fresh inputs, that is, names fresh in the whole current run. We exam-ine the expressivity of FRA’s both from the aspect of accepted languages and of bisimulation equivalence. We establish primary properties and connections between automata of this kind, and an-swer key decidability questions. As a demonstrating example, we express the theory of the pi-calculus in FRA’s and characterise bisimulation equivalence by an appropriate, and decidable in the finitary case, notion in these automata
Primi risultati del progetto LIFE+ sulle analisi microbiologiche delle acque nel Parco dei Gessi dell’Emilia Romagna
Dal 2010 è in corso il Progetto Life + 08NAT/IT/000369 “Gypsum”
2, cofinanziato dall’Unione Europea, finalizzato alla tutela
e gestione dei principali ambienti gessosi dell’Emilia Romagna.
Nell’ambito dell’Azione A3 è previsto un monitoraggio pluriennale
dei principali acquiferi carsici sotto l’aspetto chimico e
microbiologico. Nel corso del primo anno sono state analizzate
le acque carsiche su circa 50 punti di controllo (inghiottitoi,
fiumi, torrenti in grotta, e risorgenti). In generale l’obiettivo di
questa sperimentazione è quello di valutare l’impatto di sostanze
di origine agricola o di altre forme di inquinamento, legate
ad insediamenti o attività antropiche o fattori naturali, in
acque di grotta. La sperimentazione è stata sviluppata tramite
tecniche microbiologiche classiche e di biologia molecolare
(PCR 16S rRNA e PCR-DGGE), finalizzate alla caratterizzazione
delle popolazioni microbiche presenti nei diversi siti di
prelievo e alla determinazione di loro eventuali variazioni e/o
evoluzioni. I valori di carica microbica totale determinati oscillavano
da un massimo di 3.32 ad un minimo di 0.18 log UFC/
ml e da un massimo di 2.26 fino a valori al di sotto del limite di
determinazione (1 log UFC/ml) per quanto riguarda i coliformi
totali e fecali. Le analisi genetiche hanno mostrato la presenza
di numerosi specie batteriche (Agrobacterium tumefaciens,
Pseudomonas spp., Rahnella aquatilis, Stenotrophomonas
maltophilia, Pedobacter swuonensis, Enterobacter spp., Aeromonas
hydrophila, Citrobacter, Klebsiella and Raoultella). I
microrganismi identificati possono avere diverse origini, alcuni
provengono dal terreno, altri possono essere comuni contaminanti
delle acque ed altri avere un’origine antropica (batteri
fecali). Fino a questo step del progetto, l’analisi PCR-DGGE ha
evidenziato le evoluzioni ecologiche, in termine di popolazioni
microbiche, presenti tra i diversi campioni e i diversi siti di
campionamento all’interno di una stessa grotta.The Project Life + 08NAT/IT/000369 “Gypsum” 2, co-financed
by the European Union, has started in the spring
of 2010. This project aims to protect and manage the main
karst caves and sites of Emilia-Romagna region. The A3
action provides a periodic monitoring of the main karst
aquifers in terms of chemistry and microbiology.
During the first year and a half, karst waters of 50 control
points were analysed (sinking streams, rivers and streams
in caves, and resurgences).
The objective of this study is to evaluate the impact, in the
waters of the cave, of agricultural substances or other forms
of pollution or settlements related to human activities
or natural factors. The experiment was developed using
traditional microbiology techniques and molecular biology
techniques (PCR and 16S rRNA PCR-DGGE), focused on
the characterization of microbial populations in the different
sampling sites and determination of their variations
and/or changes. The total microbial concentration ranged
from a maxiimum of 3.32 or 2.26 to values below the limit
of detection (1 log CFU/ml) for total and faecal colifroms,
respectively. The genetic analysis showed the presence of
numerous bacterial species (Agrobacterium tumefaciens,
Pseudomonas spp., Rahnella aquatilis, Stenotrophomonas
maltophilia, Pedobacter swuonensis, Enterobacter spp.,
Aeromonas hydrophila, Citrobacter, Klebsiella and Raoultella).
The organisms identified have different origins, some
come from the ground, others are common water contaminants
and others derive from human activities (faecal
bacteria). Up to now, PCR-DGGE revealed the ecological
changes, in terms of microbial populations present in the
samples, and different sampling sites within the same cave
Parallel vs. Sequential Belief Propagation Decoding of LDPC Codes over GF(q) and Markov Sources
A sequential updating scheme (SUS) for belief propagation (BP) decoding of
LDPC codes over Galois fields, , and correlated Markov sources is
proposed, and compared with the standard parallel updating scheme (PUS). A
thorough experimental study of various transmission settings indicates that the
convergence rate, in iterations, of the BP algorithm (and subsequently its
complexity) for the SUS is about one half of that for the PUS, independent of
the finite field size . Moreover, this 1/2 factor appears regardless of the
correlations of the source and the channel's noise model, while the error
correction performance remains unchanged. These results may imply on the
'universality' of the one half convergence speed-up of SUS decoding
Assessment of interferon gamma and indoleamine 2,3-dioxygenase 1 analysis during respiratory syncytial virus infection in infants in Italy: an observational case-control study
Large Deviation Property of Free Energy in p-Body Sherrington-Kirkpatrick Model
Cumulant generating function phi(n) and rate function Sigma(f) of the free
energy is evaluated in p-body Sherrington-Kirkpatrick model by using the
replica method with the replica number n finite. From a perturbational
argument, we show that the cumulant generating function is constant in the
vicinity of n = 0. On the other hand, with the help of two analytic properties
of phi(n), the behavior of phi(n) is derived again. However this is also shown
to be broken at a finite value of n, which gives a characteristic value in the
rate function near the thermodynamic value of the free energy. Through the
continuation of phi(n) as a function of n, we find out a way to derive the 1RSB
solution at least in this model, which is to fix the RS solution to be a
monotone increasing function.Comment: 7 pages, 5 figures. accepted for publication in J.Phs.Soc.Jp
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