Maintaining strong mutual visibility of an evader moving over the reduced visibility graph

In this paper, we address the problem of determining whether a mobile robot, called the pursuer, is able to maintain strong mutual visibility (a visibility notion between regions over a convex partition of the environment) of an antagonist agent, called the evader. We frame the problem as a non cooperative game. We consider the case in which the pursuer and the evader move at bounded speed, traveling in a known polygonal environment with or without holes, and in which there are no restrictions as to the distance that might separate the agents. Unlike our previous efforts (Murrieta-Cid et al. in Int J Robot Res 26:233–253, 2007), we give special attention to the combinatorial problem that arises when searching for a solution through visiting several locations in an environment with obstacles. In this paper we take a step further, namely, we assume an antagonistic evader who moves continuously and unpredictably, but with a constraint over its set of admissible motion policies, as the evader moves in the shortest-path roadmap, also called the reduced visibility graph (RVG). The pursuer does not know which among the possible paths over the RVG the evader will choose, but the pursuer is free to move within all the environment. We provide a constructive method to solve the decision problem of determining whether or not the pursuer is able to maintain strong mutual visibility of the evader. This method is based on an algorithm that computes the safe areas (areas that keep evader surveillance) at all times. We prove decidability of this problem, and provide a complexity measure to this evader surveillance game; both contributions hold for any general polygonal environment that might or not contain holes. All our algorithms have been implemented and we show simulation results.     

A crucial experiment resubmitted.

Presents the "experiment" conducted by the prophet Elijah in 1 Kings 18:17–40 in which the priests of Baal and Elijah each sacrificed a bull and invoked the name of their respective god, but only Elijah's god responded. Satirical comments of 3 "reviewers" of psychological articles are included to show the ethical and methodological issues that might be raised if such an experiment were conducted today. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Renaming and the weakest family of failure detectors

We address the question of the weakest failure detector to circumvent the impossibility of $(2n-2)$ -renaming in a system of up to $n$ participating processes. We derive that in a restricted class of eventual failure detectors there does not exist a single weakest oracle, but a weakest family of oracles $\zeta _n$ : every two oracles in $\zeta _n$ are incomparable, and every oracle that allows for solving renaming provides at least as much information about failures as one of the oracles in $\zeta _n$ . As a by product, we obtain one more evidence that renaming is strictly easier to solve than set agreement.     

Correlations of the craze profile in PMMA with Dugdale's plastic zone profile

The craze opening profile in PMMA has been determined as a function of stress intensity using interference optics and a special wedge loading device. An attempt was made to correlate the craze profile with the corresponding parameters (crack opening displacement and plastic zone length) predicted by the Dugdale model. Over the mid-range of stress intensities (K _I=0.4 to 1.0 MPa m^1/2), samples which were annealed after precracking were found to exhibit a profile similar in shape but smaller than that predicted by the Dugdale model. The lower limit of this range marks the critical stress intensity for crazing in PMMA. Both the craze length and the opening at the craze-crack interface increase with increasing stress intensity and, due to strain-hardening of the craze material, reach maximum values of about 40m and 3m respectively atK _I=1.0 MPa m^1/2. Experimental uncertainties cannot account for the profile difference and it is therefore concluded that the Dugdale model is not fully adequate to describe craze geometries in PMMA. The discrepency between the Dugdale model and the experimental data is suggested to be due to either fibril strain-hardening and/or the formation of a plane strain plastic zone ahead of the craze.     

On Conducting Simultaneous Versus Sequential Engineering Activities in Risky R&D

We consider development projects in which the activities can be classified in two types: uncertainty resolving R&D efforts that accumulate in the form of knowledge to eventually give rise to a discovery; and routine technical investments which aim at improving the profitability of the project once the discovery has been made. The advantage of initiating routine preparatory activities prior to the achievement of a technological breakthrough in such projects, sometimes termed as 'concurrent engineering', is analyzed within a suitable dynamic optimization framework. The optimal double expenditure policy is compared with the conservative delayed investment policy, under which all the routine engineering activities are delayed until the risky R&D efforts culminate in a breakthrough. A criterion for the optimality of the latter policy is developed on the basis of the probability distribution of the discovery date. The application of the criterion is illustrated for a variety of specifications regarding the uncertainty associated with the R&D process. We find that simultaneous investment is the optimal policy for a large class of probability distributions. However, if the conditional probability of immediate discovery is always below some critical value, it is optimal to delay the preparatory activities until the discovery.     

Kinetik und Mechanismus der Photolyse von Aryldiazoniumsalzen in Methanol. Ermittlung absoluter Geschwindigkeitskonstanten einiger Teilreaktionen

Kinetics and Mechanism of Aryldiazonium Salt Photolysis in Methanol. Determination of Absolute Rate Constants of Some Reaction Steps For benzene diazonium tetrafluoroborate and some p-substituted derivatives, the following values are determined:

• velocity constants for the photochemical electron transfer from pyrene and benzanthracene to aryl diazonium salts in acetonitrile solution (determination by quenching the donor fluorescence).
• velocity constants for electron transfer under the condition of pulse radiolysis in tert.-butanol-water solution;
• quantum yields and product composition (ArOMe, ArF and ArH, respectively) for the photolyses in methanol in the presence of varying concentrations of 2-methyl-2-nitroso-propane as a quencher of the thermal chain reaction.

The electron transfer reaction comes out be a diffusion controlled reaction, k_E = 2 …︁ 3 × 10¹⁰ M⁻¹ s⁻¹. For the total reaction a kinetic model is set up which affords absolute velocity constants from the experimental results for the following steps: Hydrogen transfer within the case radical pair \documentclass{article}\pagestyle{empty}\begin{document}$ \overline {{\rm Ar} - {\rm N} = {\rm N}{\rm . CH}_{\rm 3} {\rm OH}{\rm .}} {\rm }^ \oplus $\end{document} (formation of ArH) k_H ≈ 10¹¹ s⁻¹; Maximal values for the photo-solvolyses (formation of Ar^⊕ → ArOMe and ArF, respectively), k_s ≲ 10⁻¹; Trapping of aryl radicals outside of the solvent cage by t-BuNO, k_q ≈ 2 × 10⁷ M⁻¹ s⁻¹. The results are discussed in the light of the kinetic model and some other facts.     

The social costs of emotional suppression: A prospective study of the transition to college.

There is growing interest in understanding how emotion regulation affects adaptation. The present study examined expressive suppression (which involves inhibiting the overt expression of emotion) and how it affects a critical domain of adaptation, social functioning. This investigation focused on the transition to college, a time that presents a variety of emotional and social challenges. Analyses focused on 2 components of suppression: a stable component, representing individual differences expressed both before and after the transition, and a dynamic component, representing variance specific to the new college context. Both components of suppression predicted lower social support, less closeness to others, and lower social satisfaction. These findings were robustly corroborated across weekly experience reports, self-reports, and peer reports and are consistent with a theoretical framework that defines emotion regulation as a dynamic process shaped by both stable person factors and environmental demands. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Bone mineral density and turnover in children with systemic juvenile chronic arthritis

OBJECTIVE: To assess bone mineral status in a group of children with systemic type juvenile chronic arthritis (JCA), which places them at high risk to develop osteoporosis. METHODS: Bone mineral density (BMD) was measured in 17 children aged 6-18 yrs (mean 14.9 +/- 4.5) with systemic JCA and in 18 matched controls by dual energy x-ray absorptiometry. Bone turnover was determined by quantitative bone scintigraphy, using quantitative single photon emission computed tomography based on skeletal uptake of methylene diphosphonates (MDP uptake). Serum concentrations of minerals, osteocalcin, and bone alkaline phosphatase were determined. Nutrient intake was assessed by a 24 hour dietary recall. RESULTS: Patients with systemic JCA who received corticosteroid therapy had significantly reduced BMD in both the lumbar spine (p < 0.05) and the femoral neck (p < 0.05) compared to controls, whereas BMD values of the non-steroid systemic JCA patients were not different from controls. Bone turnover measurement by MDP uptake showed no difference between patients with JCA and controls. Levels of calcium, phosphorus, alkaline phosphatase. and osteocalcin were within normal limits in all patients. CONCLUSION: Patients with systemic JCA receiving longterm steroid treatment may develop a significant decrease in BMD. The normal MDP uptake values together with normal osteocalcin levels that we observed in our patients indicate that their disease is not associated with enhancement of bone turnover rates. These observations might have therapeutic implications for prevention and management of osteoporosis in JCA.     

An improved method to create nitrocellulose particles suitable for the immobilization of antigen and antibody

A method is described for producing 1-3 microns sized particles of nitrocellulose (NC) which are able to absorb protein. Protein is absorbed onto preformed particles made by first dissolving a sheet of nitrocellulose paper in DMSO, and then precipitating it with sodium carbonate/bicarbonate buffer. The efficiency of binding is the same as that of an equivalent sheet of non-processed NC filter paper. Antibodies absorbed onto preformed particles are not exposed to DMSO and carbonate buffer and therefore retain a high antigen binding capacity. Antigen and antibody-absorbed NC preformed particles were used to capture antibody and antigen, respectively. Using lysis buffer, the captured antibodies and antigens were readily released from the NC particles. This makes the latter an appropriate matrix for immunoprecipitation assays either for an antigen or for specific antibody. Antigen-coated NC particles were specifically aggregated ('agglutinated') by specific antibodies and thus can be used in semi-quantitative tests.     

ICA1L Is Associated with Small Vessel Disease: A Proteome-Wide Association Study in Small Vessel Stroke and Intracerebral Haemorrhage

Small vessel strokes (SVS) and intracerebral haemorrhages (ICH) are acute outcomes of cerebral small vessel disease (SVD). Genetic studies combining both phenotypes have identified three loci associated with both traits. However, the genetic cis-regulation at the protein level associated with SVD has not been studied before. We performed a proteome-wide association study (PWAS) using FUSION to integrate a genome-wide association study (GWAS) and brain proteomic data to discover the common mechanisms regulating both SVS and ICH. Dorsolateral prefrontal cortex (dPFC) brain proteomes from the ROS/MAP study (N = 376 subjects and 1443 proteins) and the summary statistics for the SVS GWAS from the MEGASTROKE study (N = 237,511) and multi-trait analysis of GWAS (MTAG)-ICH–SVS from Chung et al. (N = 240,269) were selected. We performed PWAS and then a co-localization analysis with COLOC. The significant and nominal results were validated using a replication dPFC proteome (N = 152). The replicated results (q-value < 0.05) were further investigated for the causality relationship using summary data-based Mendelian randomization (SMR). One protein (ICA1L) was significantly associated with SVS (z-score = −4.42 and p-value = 9.6 × 10⁻⁶) and non-lobar ICH (z-score = −4.8 and p-value = 1.58 × 10⁻⁶) in the discovery PWAS, with a high co-localization posterior probability of 4. In the validation PWAS, ICA1L remained significantly associated with both traits. The SMR results for ICA1L indicated a causal association of protein expression levels in the brain with SVS (p-value = 3.66 × 10⁻⁵) and non-lobar ICH (p-value = 1.81 × 10⁻⁵). Our results show that the association of ICA1L with SVS and non-lobar ICH is conditioned by the cis-regulation of its protein levels in the brain.