Cover Feature: A Comparative Study of in vitro Assays for Predicting the Nonspecific Binding of PET Imaging Agents in vivo (ChemMedChem 7/2020)

Nonspecific binding (NSB) is a key parameter in optimizing PET imaging tracers. We compared the ability to predict NSB of three available methods: LIMBA, rat f_u,brain, and CHI(IAM). Even though NSB is often associated with lipophilicity, we observed that logD does not correlate with any of these assays, clearly indicating that lipophilicity, while influencing NSB, is insufficient to predict it. A cross-comparison of the methods showed that all three correlate and are useful predictors of NSB. The three assays, however, rank the molecules slightly differently, illustrating the challenge of comparing molecules within a narrow chemical space. We also noted that CHI(IAM) values more effectively predict V_NS, a measure of in vivo NSB in the human brain. CHI(IAM) measurements might be a closer model of the actual physicochemical interaction between PET tracer candidates and cell membranes, and seems to be the method of choice for the optimization of in vivo NSB.     

Analysis of seed oil from ricinus communis and dimorphoteca pluvialis by gas and supercritical fluid chromatography

The seed oils from Dimorphoteca pluvialis and Ricinus communis contain hydroxy fatty acids. Dimorphoteca pluvialis contains Δ-9-hydroxy-10t, 12t-octadecadienoic acid (dimorphecolic acid) and R. communis contains Δ-12-hydroxy-9c-octadecenoic acid (ricinoleic acid). The oils were derivatized and analyzed to determine the content of hydroxy fatty acids. The trimethylsilyl fatty acid methyl ester (TMS-FAME) derivatives were analyzed by capillary gas chromatography (GC), and the free fatty acid (FFA) derivatives and the oils were analyzed by capillary supercritical fluid chromatography (SFC). Further, mass spectroscopy of the TMS-FAME derivatives was performed to check the purity of the derivatives. The results from the GC analyses of TMS-FAME corresponded to the results found by SFC analysis of the FFA. The content of ricinoleic acid in the glycerolipids of R. communis was 87.7 wt%, and the content of dimorphecolic acid in D. pluvialis was 54.0 wt%. The methods were evaluated with respect to the cost, ease, and time needed for sample preparation and analysis.     

Track following servo control for rotary piezoelectric motor based primary actuation in hard disk drives

In this paper, we show the tracking performance of a rotary piezoelectric motor based hard disk drive actuator. The actuator is built and modeled for positioning servo in disk drive systems. The Piezo motor replaces the voice-coil-motor based primary actuation. Simulation and experimental results for its servo system proves that it can help to achieve track density of more than 1000?KTPI.     

A comprehensive survey of industry practice in real-time systems

Real-Time Systems - This paper presents results and observations from a survey of 120 industry practitioners in the field of real-time embedded systems. The survey provides insights into the...     

Media Reporting of Nuclear Emergencies: The Effects of Transparent Communication in a Minor Nuclear Event

IN 2008, a nuclear event occurred at Kr?ko nuclear power plant in Slovenia. Even though it was classified as level 0 on International Nuclear Event Scale, the transparency policy of the Slovenian nuclear safety authorities prompted it to notify the international community. This was the first time that the European Community Urgent Radiological Information Exchange (ECURIE) notification system was used outside the exercise framework. The event was reported in all major European. In this contribution, we report on a content analysis of media articles related to this event. The main research question was if a nuclear emergency generates significant media coverage, even in the case of a minor event and a transparent communication policy. The analysis included more than 200 articles from printed and spoken media in Slovenia and other countries. The analysis revealed a high‐intensity media coverage, emotional reactions and heated political discussion. The main media sources in countries with open political discussions on nuclear energy end up being the politicians, rather than resident experts.     

Cryptographic and Physical Zero-Knowledge Proof Systems for Solutions of Sudoku Puzzles

We consider cryptographic and physical zero-knowledge proof schemes for Sudoku, a popular combinatorial puzzle. We discuss methods that allow one party, the prover, to convince another party, the verifier, that the prover has solved a Sudoku puzzle, without revealing the solution to the verifier. The question of interest is how a prover can show: (i) that there is a solution to the given puzzle, and (ii) that he knows the solution, while not giving away any information about the solution to the verifier. In this paper we consider several protocols that achieve these goals. Broadly speaking, the protocols are either cryptographic or physical. By a cryptographic protocol we mean one in the usual model found in the foundations of cryptography literature. In this model, two machines exchange messages, and the security of the protocol relies on computational hardness. By a physical protocol we mean one that is implementable by humans using common objects, and preferably without the aid of computers. In particular, our physical protocols utilize items such as scratch-off cards, similar to those used in lotteries, or even just simple playing cards. The cryptographic protocols are direct and efficient, and do not involve a reduction to other problems. The physical protocols are meant to be understood by “lay-people” and implementable without the use of computers. Research of R. Gradwohl was supported by US-Israel Binational Science Foundation Grant 2002246. Research of M. Naor was supported in part by a grant from the Israel Science Foundation. Research of B. Pinkas was supported in part by the Israel Science Foundation (grant number 860/06). Research of G.N. Rothblum was supported by NSF grant CNS-0430450 and NSF grant CFF-0635297.     

Computing occluding and transparent motions

Computing the motions of several moving objects in image sequences involves simultaneous motion analysis and segmentation. This task can become complicated when image motion changes significantly between frames, as with camera vibrations. Such vibrations make tracking in longer sequences harder, as temporal motion constancy cannot be assumed. The problem becomes even more difficult in the case of transparent motions.A method is presented for detecting and tracking occluding and transparent moving objects, which uses temporal integration without assuming motion constancy. Each new frame in the sequence is compared to a dynamic internal representation image of the tracked object. The internal representation image is constructed by temporally integrating frames after registration based on the motion computation. The temporal integration maintains sharpness of the tracked object, while blurring objects that have other motions. Comparing new frames to the internal representation image causes the motion analysis algorithm to continue tracking the same object in subsequent frames, and to improve the segmentation.     

Tight lower bounds for certain parameterized NP-hard problems

Based on the framework of parameterized complexity theory, we derive tight lower bounds on the computational complexity for a number of well-known NP-hard problems. We start by proving a general result, namely that the parameterized weighted satisfiability problem on depth-t circuits cannot be solved in time n^o(k)m^O(1), where n is the circuit input length, m is the circuit size, and k is the parameter, unless the (t − 1)-st level W[t − 1] of the W-hierarchy collapses to FPT. By refining this technique, we prove that a group of parameterized NP-hard problems, including weighted sat, hitting set, set cover, and feature set, cannot be solved in time n^o(k)m^O(1), where n is the size of the universal set from which the k elements are to be selected and m is the instance size, unless the first level W[1] of the W-hierarchy collapses to FPT. We also prove that another group of parameterized problems which includes weighted q-sat (for any fixed q 2), clique, independent set, and dominating set, cannot be solved in time n^o(k) unless all search problems in the syntactic class SNP, introduced by Papadimitriou and Yannakakis, are solvable in subexponential time. Note that all these parameterized problems have trivial algorithms of running time either n^km^O(1) or O(n^k).