Average sex ratio and population maintenance cost

The ratio of males to females in a population is a meaningful characteristic of sexual species. The reason for this biological property to be available to the observers of nature seems to be a question never asked. Introducing the notion of historically adapted populations as global minimizers of maintenance cost functions, we propose a theoretical explanation for the reported stability of this feature. This mathematical formulation suggests that sex ratio could be considered as an indirect result shaped by the antagonism between the size of the population and the finiteness of resources.Comment: 18 pages. A revised new version, where all the text was improved to become more clear for the reade

Dismissal Disputes and Endogenous Sorting

Dismissal disputes occur mostly in recessions and often lead to long and costly contract termination procedures. This paper investigates how dispute procedures may affect the job-matching process. First we present a simple accounting framework that corresponds with general dismissal legislation, but is sufficiently flexible to accommodate country-specific legislation. Detailed information from a sample of 2,191 disputes that occurred in the Netherlands between 2006 and 2009 is used to adjust the framework to Dutch institutional specificity. The resulting equilibrium matching model is solved to explain endogenous sorting between lengthy and costly firing procedures. The model also rationalizes the longevity of the dual Dutch model and its political resilience

Dismissal Disputes and Endogenous Sorting

Dismissal disputes occur mostly in recessions and often lead to long and costly contract termination procedures. This paper investigates how dispute procedures may affect the job-matching process. First we present a simple accounting frame- work that corresponds with general dismissal legislation, but is sufficiently flexible to accommodate country-specific legislation. Detailed information from a sample of 2,191 disputes that occurred in the Netherlands between 2006 and 2009 is used to adjust the framework to Dutch institutional specificity. The resulting equilibrium matching model is solved to explain endogenous sorting between lengthy and costly firing procedures. The model also rationalizes the longevity of the dual Dutch model and its political resilience

Exploring Constrained Type-2 fuzzy sets

Fuzzy logic has been widely used to model human reasoning thanks to its inherent capability of handling uncertainty. In particular, the introduction of Type-2 fuzzy sets added the possibility of expressing uncertainty even on the definition of the membership functions. Type-2 sets, however, don’t pose any restrictions on the continuity or convexity of their embedded sets while these properties may be desirable in certain contexts. To overcome this problem, Constrained Type-2 fuzzy sets have been proposed. In this paper, we focus on Interval Constrained Type-2 sets to see how their unique structure can be exploited to build a new inference process. This will set some ground work for future developments, such as the design of a new defuzzification process for Constrained Type-2 fuzzy systems

An epistatic mini-circuitry between the transcription factors Snail and HNF4a controls liver stem cell and hepatocyte features exhorting opposite regulation on stemness-inhibiting microRNAs

Preservation of the epithelial state involves the stable repression of EMT program while maintenance of the stem compartment requires the inhibition of differentiation processes. A simple and direct molecular mini-circuitry between master elements of these biological processes, may provide the best device to keep balanced such complex phenomena. In this work, we show that in hepatic stem cell Snail, a transcriptional repressor of the hepatocyte differentiation master gene HNF4, directly represses the expression of the epithelial microRNAs-200c and -34a, which in turn target several stem cell genes. Notably, in differentiated hepatocytes HNF4, previously identified as a transcriptional repressor of Snail, induces the microRNAs-34a and -200a, b, c that, when silenced, causes epithelial dedifferentiation and reacquisition of stem traits. Altogether these data unveiled Snail, HNF4 and microRNAs -200a, b, c and -34a as epistatic elements controlling hepatic stem cell maintenance/differentiation

Bacillus subtilis for the control of powdery mildew on cucumber and zucchini squash.

Application of concentrated metabolites of Bacillus subtilis - CMBS - (5,000 ug/mL) one and 24 h before or after inoculation of Sphaerotheca fuliginea (3 x 10 4 conidia/mL) reduced the number of lesions on cucumber leaves by 90-99%. The average number of lesions on control plants was 16.7 per leaf. A wettable powder product formulated with cells (10%) and metabolites (10%) of B. subtilis (WPBS), and CMBS sprayed on cucumber plants (1,000 ug/mL and 10,000 ug/mL) twice a week totally controlled powdery mildew. In the control treatment, 18 days after the first spray, the percent leaf surface covered by lesions was 99.0 and 46.7%, on the cotyledonary and expanded leaves, respectively. In the control treatment, 30 days after the first spray, the percent leaf surface with lesions was 26.1%, while leaves sprayed with CMBS presented no lesions. The fresh weight per plant was 4.3 g in the control treatment; 12.2 g, and 10.2 for plants sprayed with CMBS at the concentration of 1,000 and 10,000 ug/mL, respectively; and 9.7 g and 10.1 g for plants sprayed with WPBS 1,000 and 10,000 ug/mL, respectively. For zucchini squash, CMBS (5,000 ug/mL) sprayed every 2,4, and 6 days showed reductions in lesioned leaf surface of 100.0,98.3, and 94,7%, respectively

Best parameter choice of Stochastic Resonance to enhance fault signature in bearings

Stochastic Resonance (SR) is a phenomenon studied and exploited for telecommunication, which permits the detection and amplification of weak signals by the assistance of noise. The first papers on this topic date back to the early 80s and were developed to explain some periodic natural phenomena. Other applications are in neuroscience, biology, medicine and, obviously, mechanics. Recently, a few researchers have tried to apply this technique for detecting faults in mechanical systems and also bearings. In this paper we discuss the best way to select the parameters to augment the performance of the algorithm. This is probably the main drawback of SR, since in system identification the procedure should be as blind as possible to be efficient and widely applicable. The classical bi-stable potential form is adopted in our study, with three parameters to be selected. Based on numerical tests, a characteristic trend of the amplification factor has been found with respect to the parameters variation, so that a general rule is consequently determined which gives the best performances in terms of detection and amplification. The SR algorithm is tested on both simulated and experimental data showing a good capacity of increasing the signal to noise ratio