A synthetic peptide corresponding to a conserved heptad repeat domain is a potent inhibitor of Sendai virus-cell fusion: an emerging similarity with functional domains of other viruses

A series of peptides derived from three domains within the fusion protein of Sendai virus was synthesized and examined for their potential to inhibit the fusion of the virus with human red blood cells. These domains include the 'fusion peptide' and two heptad repeats, one adjacent to the fusion peptide (SV-163) and the other to the transmembrane domain (SV-473). Of all the peptides tested, only SV-473 was highly inhibitive. Using fluorescently-labelled peptides, the mechanism through which the SV-473 peptide inhibits the haemolytic activity of the virus was investigated. The results suggest that interactions of the active peptide with virion elements and lipid membranes are involved. Since it has recently been found that synthetic peptides corresponding to putative coiled-coil domains of the human immunodeficiency virus (HIV) type 1 transmembrane protein gp41 are potent inhibitors of HIV, we discuss the general property of virus-derived coiled-coil peptides as inhibitors of viral infection.     

Vision Based Output Feedback Control of Micro Aerial Vehicles in Indoor Environments

We present a new image based visual servoing (IBVS) approach for control of micro aerial vehicles (MAVs) in indoor environments. Specifically, we show how a MAV can be stabilized and guided using only corridor lines viewed on a front facing camera and angular velocity measurements. Since the suggested controller does not include explicit attitude feedback it does not require the use of accelerometers which are susceptible to vibrations, nor complex attitude estimation algorithms. The controller also does not require direct velocity measurements which are difficult to obtain in indoor environments. The paper presents the new method, stability analysis, simulations and experiments.     

A primal-dual perspective of online learning algorithms

We describe a novel framework for the design and analysis of online learning algorithms based on the notion of duality in constrained optimization. We cast a sub-family of universal online bounds as an optimization problem. Using the weak duality theorem we reduce the process of online learning to the task of incrementally increasing the dual objective function. The amount by which the dual increases serves as a new and natural notion of progress for analyzing online learning algorithms. We are thus able to tie the primal objective value and the number of prediction mistakes using the increase in the dual. Editors: Hans Ulrich Simon, Gabor Lugosi, Avrim Blum. A preliminary version of this paper appeared at the 19th Annual Conference on Learning Theory under the title “Online learning meets optimization in the dual”.     

Active sampling for multiple output identification

We study functions with multiple output values, and use active sampling to identify an example for each of the possible output values. Our results for this setting include: (1) Efficient active sampling algorithms for simple geometric concepts, such as intervals on a line and axis parallel boxes. (2) A characterization for the case of binary output value in a transductive setting. (3) An analysis of active sampling with uniform distribution in the plane. (4) An efficient algorithm for the Boolean hypercube when each output value is a monomial. Editors: Hans Ulrich Simon, Gabor Lugosi, Avrim Blum. A preliminary version of this work was presented in the 19th Annual Conference on Learning Theory (COLT), 2006. This work was supported in part by the IST Programme of the European Community, under the PASCAL Network of Excellence, IST-2002-506778, by a grant No. 1079/04 from the Israel Science Foundation, by a grant from BSF and an IBM faculty award. This publication only reflects the authors’ views.     

Minimizing crosstalk in three-axial induction magnetometers

A model for crosstalk in three-axial induction magnetometers has been developed theoretically and verified experimentally. The effect of crosstalk on the magnetometer accuracy has been analyzed. It has been found that the inevitable crosstalk in the transverse coils has two components: one due to the applied magnetic flux and the other due to the secondary flux produced by the electric current in the longitudinal coil. The first component has a constant magnitude. The phase of the second component, relative to the first one, is nearly 180° at low frequencies, 90° at resonance, and 0° at high frequencies. Its magnitude approaches zero at low frequencies, has the maximum at resonance, and then drops off by a factor equal to the coils' quality factor and approaches the first component value. As a result, the crosstalk due to the applied flux is dominant at low frequencies. At a frequency just below the resonance, the crosstalk is very low, if no magnetic feedback is applied. Just above the resonance, the crosstalk reaches the maximum because of the rapid increase in the secondary flux. Applying a strong enough magnetic feedback nearly flattens the crosstalk amplitude response. However, an undesirable effect of the feedback is that it significantly increases the minimum crosstalk value. A very low crosstalk at a single frequency can be beneficial for magnetometers tuned to a narrow frequency band. It can also be beneficial for wide-band magnetometers to measure their mechanical orthogonality with a minimum effect of crosstalk.     

Spatial analysis of air pollution and cancer incidence rates in Haifa Bay, Israel

The Israel National Cancer Registry reported in 2001 that cancer incidence rates in the Haifa area are roughly 20% above the national average. Since Haifa has been the major industrial center in Israel since 1930, concern has been raised that the elevated cancer rates may be associated with historically high air pollution levels. This work tests whether persistent spatial patterns of metrics of chronic exposure to air pollutants are associated with the observed patterns of cancer incidence rates. Risk metrics of chronic exposure to PM₁₀, emitted both by industry and traffic, and to SO₂, a marker of industrial emissions, was developed. Ward-based maps of standardized incidence rates of three prevalent cancers: Non-Hodgkin's lymphoma, lung cancer and bladder cancer were also produced. Global clustering tests were employed to filter out those cancers that show sufficiently random spatial distribution to have a nil probability of being related to the spatial non-random risk maps. A Bayesian method was employed to assess possible associations between the morbidity and risk patterns, accounting for the ward-based socioeconomic status ranking. Lung cancer in males and bladder cancer in both genders showed non-random spatial patterns. No significant associations between the SO₂-based risk maps and any of the cancers were found. Lung cancer in males was found to be associated with PM₁₀, with the relative risk associated with an increase of 1 μg/m³ of PM₁₀ being 12%. Special consideration of wards with expected rates < 1 improved the results by decreasing the variance of the spatially correlated residual log-relative risk.     

Selective cytotoxicity of dermaseptin S3 toward intraerythrocytic Plasmodium falciparum and the underlying molecular basis

The antimicrobial activity of various naturally occurring microbicidal peptides was reported to result from their interaction with microbial membrane. In this study, we investigated the cytotoxicity of the hemolytic peptide dermaseptin S4 (DS4) and the nonhemolytic peptide dermaseptin S3 (DS3) toward human erythrocytes infected by the malaria parasite Plasmodium falciparum. Both DS4 and DS3 inhibited the parasite's ability to incorporate [3H]hypoxanthine. However, while DS4 was toxic toward both the parasite and the host erythrocyte, DS3 was toxic only toward the intraerythrocytic parasite. To gain insight into the mechanism of this selective cytotoxicity, we labeled the peptides with fluorescent probes and investigated their organization in solution and in membranes. In Plasmodium-infected cells, rhodamine-labeled peptides interacted directly with the intracellular parasite, in contrast to noninfected cells, where the peptides remained bound to the erythrocyte plasma membrane. Binding experiments to phospholipid membranes revealed that DS3 and DS4 had similar binding characteristics. Membrane permeation studies indicated that the peptides were equally potent in permeating phosphatidylserine/phosphatidylcholine vesicles, whereas DS4 was more permeative with phosphatidylcholine vesicles. In aqueous solutions, DS4 was found to be in a higher aggregation state. Nevertheless, both DS3 and DS4 spontaneously dissociated to monomers upon interaction with vesicles, albeit with different kinetics. In light of these results, we propose a mechanism by which dermaseptins permeate cells and affect intraerythrocytic parasites.     

The interdisciplinary engineering knowledge genome

Parallel to the concept of the human genome and its impact on biology and other disciplines, we revealed a similar concept in engineering sciences, termed the ??Interdisciplinary Engineering Knowledge Genome??, which is an organized collection of system and method ??genes?? that encode instructions for generating new systems and methods in diverse engineering disciplines. Resting on the firm mathematical foundation of combinatorial representations, the Interdisciplinary Engineering Knowledge Genome unifies many engineering disciplines, providing a basis for transforming knowledge between them, supporting new educational practices, promoting inventions, aiding design, and bootstrapping new discoveries in engineering and science. Given the formal underlying combinatorial representations, these merits could be automated. This paper elucidates this new concept and demonstrates its value and power in engineering design.     

Measuring academic influence using heterogeneous author-citation networks

Scientometrics - Academic influence has been traditionally measured by citation counts and metrics derived from it, such as H-index and G-index. PageRank based algorithms have been used to give...