A Continuous-Discontinuous Second-Order Transition in the Satisfiability of Random Horn-SAT Formulas

We compute the probability of satisfiability of a class of random Horn-SAT formulae, motivated by a connection with the nonemptiness problem of finite tree automata. In particular, when the maximum clause length is 3, this model displays a curve in its parameter space along which the probability of satisfiability is discontinuous, ending in a second-order phase transition where it becomes continuous. This is the first case in which a phase transition of this type has been rigorously established for a random constraint satisfaction problem

Probabilistic phenomena in random combinatorial problems

This is an experimental investigation of three combinatorial problems. I examined the average-case complexity of random 3-SAT and of 3-Colorability of random graphs, and the satisfiability of random 1-3-HornSAT. All these problems, not only are interesting for their own sake, but also are of great practical importance since many other problems in computer science, engineering and other fields can be reduced to these. We systematically explored a large part of the problems' space, varying the size and the constrainedness of the instances, as well as the tools we used to solve them. We observed new phase transitions from polynomial to exponential complexity for random 3-SAT. A similar picture emerged for 3-Colorability. These experimental observations are important for understanding the inherent computational complexity of the problems. In the case of random 1-3-HornSAT, our findings suggest that there is a threshold at which the satisfiability changes from 1 to 0

The phase transition in the random 1-3-HornSAT problem

This paper presents a study of the satis ability of random Horn formulae and a search for a phase transition. This is a problem similar to the Satis ability problem, but, unlike the latter, Horn satis ability is tractable and thus it is easier to collect experimental data for large instances. We are also interested in Horn formulae because of their relation to nite automata. We study random Horn formulae generated according to a variation of the xed-clause-length distribution model

Tin(II) and Tin(IV) Complexes Incorporating the Oxygen Tripodal Ligands [(<i>η</i>⁵-C₅R₅)Co{P(OEt)₂O}₃]⁻, (R = H, Me; Et = -C₂H₅) as Potent Inflammatory Mediator Inhibitors: Cytotoxic Properties and Biological Activities against the Platelet-Activating Factor (PAF) and Thrombin

Metal complexes displaying antiplatelet properties is a promising research area. In our methodology, Platelet-Activating Factor (PAF), the most potent lipid pro-inflammatory mediator, serves as a biological probe. The antiplatelet activity is exerted by the inhibition of the PAF-induced aggregation in washed rabbit platelets (WRPs) and in rabbit plasma rich in platelets (rPRPs). Herein, the synthesis and biological investigation of a series of organometallic tin(II) and tin(IV) complexes, featuring the oxygen tripodal Kläui ligands [(η5-C5R5)Co{P(OEt)2O}3]−, {R = H, (LOEt−); Me (L*OEt−)}, are reported. Reaction of NaLOEt (1a) and NaL*OEt (1b) with SnCl2, yielded the rare four-coordinate LOEtSnCl (2a) and L*OEtSnCl (2b) complexes. Accordingly, LOEtSnPh3 (3a) and L*OEtSnPh3 (3b) were prepared, starting from Ph3SnCl. Characterization includes spectroscopy and X-ray diffraction studies for 2a, 2b and 3b. The antiplatelet activity of the lead complexes 2b and 3a (IC50 = 0.5 μΜ) is superior compared to that of 1a and 1b, while both complexes display a pronounced inhibitory activity against thrombin (IC50 = 1.8 μM and 0.6 μM). The in vitro cytotoxic activities of 3a and 2b on human Jurkat T lymphoblastic tumor cell line is higher than that of cisplatin

Tin(II) and Tin(IV) complexes incorporating the oxygen tripodal ligands [(η5-C5R5)Co{P(OEt)2O}3] −, (R = H, Me;Et = -C2H5) as potent inflammatory mediator inhibitors:cytotoxic properties and biological activities against theplatelet-activating factor (PAF) and thrombin

Metal complexes displaying antiplatelet properties is a promising research area. In our methodology, Platelet-Activating Factor (PAF), the most potent lipid pro-inflammatory mediator, serves as a biological probe. The antiplatelet activity is exerted by the inhibition of the PAF-induced aggregation in washed rabbit platelets (WRPs) and in rabbit plasma rich in platelets (rPRPs). Herein, the synthesis and biological investigation of a series of organometallic tin(II) and tin(IV) complexes, featuring the oxygen tripodal Kläui ligands [(η 5 -C5R5 )Co{P(OEt)2O}3 ] −, {R = H, (LOEt −); Me (L*OEt −)}, are reported. Reaction of NaLOEt (1a) and NaL*OEt (1b) with SnCl2 , yielded the rare four-coordinate LOEtSnCl (2a) and L*OEtSnCl (2b) complexes. Accordingly, LOEtSnPh3 (3a) and L*OEtSnPh3 (3b) were prepared, starting from Ph3SnCl. Characterization includes spectroscopy and X-ray diffraction studies for 2a, 2b and 3b. The antiplatelet activity of the lead complexes 2b and 3a (IC50 = 0.5 µM) is superior compared to that of 1a and 1b, while both complexes display a pronounced inhibitory activity against thrombin (IC50 = 1.8 µM and 0.6 µM). The in vitro cytotoxic activities of 3a and 2b on human Jurkat T lymphoblastic tumor cell line is higher than that of cisplatin.</p

Steatosis and steatohepatitis in postmortem material from Northwestern Greece

AIM: To determine the prevalence of steatosis and steatohepatitis in a series of autopsies in Northwestern Greece