Search results for "competing"
showing 10 items of 42 documents
Moment equations in a Lotka-Volterra extended system with time correlated noise
2007
A spatially extended Lotka-Volterra system of two competing species in the presence of two correlated noise sources is analyzed: (i) an external multiplicative time correlated noise, which mimics the interaction between the system and the environment; (ii) a dichotomous stochastic process, whose jump rate is a periodic function, which represents the interaction parameter between the species. The moment equations for the species densities are derived in Gaussian approximation, using a mean field approach. Within this formalism we study the effect of the external time correlated noise on the ecosystem dynamics. We find that the time behavior of the $1^{st}$ order moments are independent on th…
Two-species model for spatial distributions of sardine and anchovy: A comparison with real data
2010
We present a study of pattern formation in a set of two coupled equations modeling two competing species. We consider generalized Lotka-Volterra equations in the presence of a multiplicative noise which models the interaction between the species and the environment. The interaction parameter between the species is a random process which obeys a stochastic differential equation with a generalized bistable potential in the presence of a periodic driving term, which accounts for the environment temperature variation.We find noise-induced spatial patterns with strong anti-correlation between the two species. We compare our theoretical results with the experimental data of the spatial distributi…
Pattern formation and spatial correlation induced by the noise in two competing species
2004
We analyze the spatio-temporal patterns of two competing species in the presence of two white noise sources: an additive noise acting on the interaction parameter and a multiplicative noise which affects directly the dynamics of the species densities. We use a coupled map lattice (CML) with uniform initial conditions. We find a nonmonotonic behavior both of the pattern formation and the density correlation as a function of the multiplicative noise intensity.
TEMPORARY CONTRACTS, EMPLOYMENT PROTECTION AND SKILL: AN APPLICATION TO SPAIN*
2011
In this paper we explain the different conversion patterns of temporary contracts by the impact of employment protection in combination with differences in productivity between workers. We use longitudinal survey data from individuals to estimate a competing risks model with multispells for Spain. The model includes correlated unobserved determinants in the transition rates to deal with selectivity. We find that workers with higher levels of education have a stronger probability of finding a permanent job. In contrast, low-educated workers have a stronger probability of ending in unemployment or another temporary contract. Furthermore, we show the importance of employment protection in affe…
A ceRNA approach may unveil unexpected contributors to deletion syndromes, the model of 5q- syndrome.
2015
In genomic deletions, gene haploinsufficiency might directly configure a specific disease phenotype. Nevertheless, in some cases no functional association can be identified between haploinsufficient genes and the deletion-associated phenotype. Transcripts can act as microRNA sponges. The reduction of transcripts from the hemizygous region may increase the availability of specific microRNAs, which in turn may exert in-trans regulation of target genes outside the deleted region, eventually contributing to the phenotype. Here we prospect a competing endogenous RNA (ceRNA) approach for the identification of candidate genes target of epigenetic regulation in deletion syndromes. As a model, we an…
A PHENOMENOLOGICAL OPERATOR DESCRIPTION OF INTERACTIONS BETWEEN POPULATIONS WITH APPLICATIONS TO MIGRATION
2013
We adopt an operatorial method based on the so-called creation, annihilation and number operators in the description of different systems in which two populations interact and move in a two-dimensional region. In particular, we discuss diffusion processes modeled by a quadratic hamiltonian. This general procedure will be adopted, in particular, in the description of migration phenomena. With respect to our previous analogous results, we use here fermionic operators since they automatically implement an upper bound for the population densities.
Clinical states of cirrhosis and competing risks.
2018
The clinical course of cirrhosis is mostly determined by the progressive increase of portal hypertension, hyperdynamic circulation, bacterial translocation and activation of systemic inflammation. Different disease states, encompassing compensated and decompensated cirrhosis and a late decompensated state, are related to the progression of these mechanisms and may be recognised by haemodynamic or clinical characteristics. While these disease states do not follow a predictable sequence, they correspond to varying mortality risk. Acute-on-chronic liver failure may occur either in decompensated or in compensated cirrhosis and is always associated with a high short-term mortality. The increasin…
Long-term outcome of older patients with newly diagnosed de novo acute promyelocytic leukemia treated with ATRA plus anthracycline-based therapy
2018
Treatment outcome in older patients with acute promyelocytic leukemia (APL) is lower compared with younger patients, mainly because of a higher induction death rate and postremission non-relapse mortality (NRM). This prompted us to design a risk-and age-adapted protocol (Programa Espanol de Tratamientos en Hematologia (PETHEMA)/HOVON LPA2005), with dose reduction of consolidation chemotherapy. Patients aged >= 60 years reported to the PETHEMA registry and were treated with all-trans retinoic acid (ATRA) plus anthracycline-based regimens according to three consecutive PETHEMA trials that were included. We compared the long-term outcomes of the LPA2005 trial with the preceding PETHEMA tria…
Midlife Cardiovascular Status and Old Age Physical Functioning Trajectories in Older Businessmen
2019
Objectives The associations between cardiovascular disease (CVD) risk and later physical functioning have been observed, but only a few studies with follow-up into old age are available. We investigated the association between cardiovascular status in midlife and physical functioning trajectories in old age. Design Prospective cohort study. Setting Helsinki Businessmen Study. Participants We studied white men born between 1919 and 1934 in the Helsinki Businessmen Study (HBS, initial n = 3490). Measurements Three CVD status groups were formed based on clinical measurements carried out in 1974: signs of CVD (diagnosed clinically or with changes in ECG, chronic disease present or used medicati…
Incidence and risk factors of post-engraftment invasive fungal disease in adult allogeneic hematopoietic stem cell transplant recipients receiving or…
2015
Studies that analyze the epidemiology and risk factors for invasive fungal disease (IFD) after engraftment in alloSCT are few in number. This single-center retrospective study included 404 alloSCT adult recipients surviving > 40 days who engrafted and were discharged without prior IFD. All patients who received >= 20 mg/day of prednisone were assigned to primary oral prophylaxis (itraconazole or low-dose voriconazole). The primary end point was the cumulative incidence (CI) of probable/proven IFD using the European Organization for Research and Treatment of Cancer and Mycoses Study Group (EORTC/MSG) criteria. The independent prognostic factors after multivariate analyses were used to constr…