Bar-Ilan University

About: Bar-Ilan University is a education organization based out in Ramat Gan, Israel. It is known for research contribution in the topics: Population & Poison control. The organization has 12835 authors who have published 34964 publications receiving 995648 citations. The organization is also known as: Bar Ilan University & BIU.

Interferon (IFN)-gamma-inducible protein-10: association with histological results, viral kinetics, and outcome during treatment with pegylated IFN-alpha 2a and ribavirin for chronic hepatitis C virus infection.

Abstract: Background. We investigated associations between interferon (IFN)-gamma-inducible protein (IP)-10 and liver histological results, viral kinetic response, and treatment outcome in patients infected with hepatitis C virus (HCV) genotypes 1-4.Methods. Plasma IP-10 was monitored before, during, and after treatment with pegylated IFN-alpha 2a and ribavirin in 265 HCV-infected patients.Results. In univariate analyses, a low baseline IP-10 level was significantly associated with low baseline viral load, rapid viral response (RVR), a sustained viral response (SVR), body mass index <= 25 kg/m(2), and less-pronounced fibrosis, inflammation, and steatosis (for HCV genotypes other than 3). When the results of the univariate analyses were included in multivariate analyses, a low plasma IP-10 level, low baseline viral load, and genotype 2 or 3 infection were independent predictors of an RVR and SVR. IP-10 levels decreased 6 weeks into treatment and remained low in patients with an SVR. By contrast, plasma levels of IP-10 rebounded in patients who had detectable HCV RNA after the completion of treatment. Using cutoff IP-10 levels of 150 and 600 pg/mL for predicting an SVR in patients infected with HCV genotype 1 yielded a specificity and sensitivity of 81% and 95%, respectively.Conclusion. Baseline IP-10 levels are predictive of the response to HCV treatment.

Information Theoretic Adaptive Radar Waveform Design for Multiple Extended Targets

Abstract: In this paper, we use an information theoretic approach to design radar waveforms suitable for simultaneously estimating and tracking parameters of multiple extended targets. Our approach generalizes the information theoretic water-filling approach of Bell to allow optimization for multiple targets simultaneously. Our paper has three main contributions. First, we present a new information theoretic design criterion for a single transmit waveform using a weighted linear sum of the mutual informations between target radar signatures and the corresponding received beams (given the transmitted waveforms). We provide a family of design criteria that weight the various targets according to priorities. Then, we generalize the information theoretic design criterion for designing multiple waveforms under a joint power constraint when beamforming is used both at the transmitter and the receiver. Finally, we provide a highly efficient algorithm for optimizing the transmitted waveforms in the cases of single waveform and multiple waveforms. We also provide simulated experiments of both algorithms based on real targets and comment on the generalization of the proposed technique for other design criteria, e.g., the linearly weighted noncausal MMSE design criterion

Lévy flights in random searches

Abstract: We review the general search problem of how to find randomly located objects that can only be detected in the limited vicinity of a forager, and discuss its quantitative description using the theory of random walks. We illustrate Levy flight foraging by comparison to Brownian random walks and discuss experimental observations of Levy flights in biological foraging. We review recent findings suggesting that an inverse square probability density distribution P(l)∼l−2 of step lengths l can lead to optimal searches. Finally, we survey the explanations put forth to account for these unexpected findings.

Photoacclimation processes in phytoplankton: mechanisms, consequences, and applications

Abstract: In nature and in the laboratory, phytoplankton cells are exposed to fast and extreme fluctuations in light intensity. These include diel and seasonal changes in irradiance, and changes stemming from vertical mixing over the light field. In algal mass cultures and photobioreactors, sim- ilar changes take place as cultures grow denser and as cells are mixed rapidly in the system. To sur- vive supraoptimal, free-radical-generating irradiance levels as well as prolonged exposure to dim light, phytoplankton species are capable of photoacclimation. Under low light, light-harvesting pig- ments such as phycobilins, chlorophylls, fucoxanthin and peridinin increase all the way to optically becoming black cells. The same pigments decrease under high light, resulting in cells being rather transparent. The opposite takes place with the photoprotective pigments β-carotene and astaxanthin and the elements of the xanthophyll cycle, all of which increase whenever cells are exposed to high irradiance levels, concomitant with enhanced activity of the antioxidant enzymes catalase, superox- ydismutase, and peroxidase. These processes are complemented by up to 5-fold changes in RUBISCO per photosystem unit (PSU) levels, and parallel changes in light-saturated photosynthetic rates. Thus, light-harvesting and utilization efficiencies are maximized under low light, whereas pho- tosynthetic carbon assimilation and throughput rates reach their peak values whenever light is suffi- ciently high. Maximal photosynthesis and growth rates have to be matched by correspondingly high respiration rates. Photoacclimation can be used to optimize biomass and target product yields in biotechnological applications.