Model Checking of Robot Gathering

Recent advances in distributed computing highlight models and algorithms for autonomous mo- bile robots that self-organize and cooperate together in order to solve a global objective. As results, a large number of algorithms have been proposed. These algorithms are given together with proofs to assess their correctness. However, those proofs are informal, which are error prone. This paper presents our study on formal verification of mobile robot algorithms. We first propose a formal model for mobile robot algorithms on anonymous ring shape network under multiplicity and asynchrony assumptions. We specify this formal model in Maude, a specification and pro- gramming language based on rewriting logic. We then use its model checker to formally verify an algorithm for robot gathering problem on ring enjoys some desired properties. As the result of the model checking, counterexamples have been found. We detect the sources of some unforeseen design errors. We, furthermore, give our interpretations of these errors

A More Faithful Formal Definition of the Desired Property for Distributed Snapshot Algorithms to Model Check the Property

The first distributed snapshot algorithm was invented by Chandy and Lamport: Chandy-Lamport distributed snapshot algorithm (CLDSA). Distributed snapshot algorithms are crucial components to make distributed systems fault tolerant. Such algorithms are extremely important because many modern key software systems are in the form of distributed systems and should be fault tolerant. There are at least two desired properties such algorithms should satisfy: 1) the distributed snapshot reachability property (called the DSR property) and 2) the ability to run concurrently with, but not alter, an underlying distributed system (UDS). This paper identifies subtle errors in a paper on formalization of the DSR property and shows how to correct them. We give a more faithful formal definition of the DSR property; the definition involves two state machines - one state machine M_UDS that formalizes a UDS and the other M_CLDSA that formalizes the UDS on which CLDSA is superimposed (UDS-CLDSA) - and can be used to more precise model checking of the DSR property for CLDSA. We also prove a theorem on equivalence of our new definition and an existing one that only involves M_CLDSA to guarantee the validity of the existing model checking approach. Moreover, we prove the second property, namely that CLDSA does not alter the behaviors of UDS

Constrained output tracking control for time-varying bilinear systems via RHC with infinite prediction horizon

The paper introduces an algorithm to design a feedback controller, which guarantees the tracking of time varying bilinear system outputs for desired values in the presence of input constraint. The proposed controller employs the ideas of receding horizon principle and constrained optimal control. A theorem for the tracking stability of closed loop system is given. An updated law of weighting matrices in the cost function to keep the input constraint condition is also proposed. Finally, the tracking behavior of the closed loop system is illustrated through a numerical example

Targeting effect of folate on cancer cell through curcumin carrier nano-system

Folate receptor (FR) is well known for its overexpression on surface of various cancer cell lines, which is identical to normal tissue. Folic-based targeting drug delivery systems, therefore, are one of the most effective targeting carriers that effectively bind to FR up-regulated cancer cells. Curcumin was used both for labeling and chemotherapy. The materials were characterized and structurally confirmed by FT-IR spectra, fluorescent images and FE-SEM images. Bioassays were conducted on HeLa and HT29 cancer cell lines after 4 and 12 hours. Results show that folic acid significantly enhanced both targeting efficiency and internalization of curcumin to FR-expressing cancer cells

Synthesis of new simplified hemiasterlin derivatives with α,β-unsaturated carbonyl moiety.

International audienceIn this Letter, we report a convenient and efficient method for the synthesis of new simplified derivatives of hemiasterlin in which the α,α-dimethylbenzylic moiety A is replaced by α,β-unsaturated aryl groups as Michael acceptor. Most of these derivatives have a strong cytotoxic activity on three human tumor cell lines (KB, Hep-G2 and MCF7). Analogs 17b and 17f showed a high cytotoxicity against KB and Hep-G2 cancer cell lines comparable to paclitaxel and ellipticine

Synthesis of new bioisosteric hemiasterlin analogues with extremely high cytotoxicity

International audienceIn this article, we report a convenient and efficient method for the synthesis of new simplified derivativesof hemiasterlin in which the α,α-dimethylbenzylic moiety A is replaced by α,β-unsaturated aryl groupsas Michael acceptor. Most of these derivatives have a strong cytotoxic activity on three human tumorcell lines (KB, Hep-G2 and MCF7). Analogs 17b and 17f showed a high cytotoxicity against KB andHep-G2 cancer cell lines comparable to paclitaxel and ellipticine

SYNTHESIS AND CYTOTOXICITY OF POLYHYDROXYLATED CHOLESTEROL DERIVATIVES

Eight polyhydroxylated cholesterol derivatives (1-8) were prepared from cholesterol, using oxidative reagents as SeO2, OsO4/NMO, HCOOH/H2O2 and BH3/ H2O2. Their structures were elucidated by using physical methods including NMR 1D and 2D. These compounds were evaluated against two cancer cell lines (Hep-G2, T98). Compounds 2, 4 and 8 inhibits human hepatocellular carcinoma cell line (Hep-G2) with IC50 4.69, 4.98 and 2.89 µg/mL, respectively. In addition, compound 8 exhibited strong cytotoxicity against T98 cell line (glioblastoma) with IC50 = 2.28 μM

Targeting effect of folate on cancer cell through curcumin carrier nano-system

Folate receptor (FR) is well known for its overexpression on surface of various cancer cell lines, which is identical to normal tissue. Folic-based targeting drug delivery systems, therefore, are one of the most effective targeting carriers that effectively bind to FR up-regulated cancer cells. Curcumin was used both for labeling and chemotherapy. The materials were characterized and structurally confirmed by FT-IR spectra, fluorescent images and FE-SEM images. Bioassays were conducted on HeLa and HT29 cancer cell lines after 4 and 12 hours. Results show that folic acid significantly enhanced both targeting efficiency and internalization of curcumin to FR-expressing cancer cells

Elaborating a people-centered approach to understanding sustainable livelihoods under climate and environmental change: Thang Binh District, Quang Nam Province, Vietnam

This paper explores the maintenance of livelihoods under climate, environmental, and economic development pressures, through the case of Thang Binh District in Quang Nam Province, Vietnam. Within widespread recognition of the need to link sustainable livelihoods approaches with climate change adaptation, there is growing awareness of the importance of people-centered approaches which keep the diverse experience, capabilities, and knowledges of the most vulnerable at the heart of sustainable livelihoods thinking. In response, this paper explores the conditions for changes in modes of livelihoods in a case study area where top-down strategies for sustainable livelihoods are met with residents’ diverse experiences of vulnerability, and where climate and environmental changes shape residents’ relations with the landscape. The research is undertaken via interviews with residents, farmers/fishers, and local government officials. Our study finds that whilst government-led initiatives for sustainable livelihoods are welcomed in the locality, inflexible policies can make it challenging for the most vulnerable people to access support. Moreover, residents see the capacity to live with and respond to extreme weather events as a critical component of maintaining a sustainable livelihood. Our findings reinforce international literature, showing that ‘the poor’ are not a homogenous category, and illustrate the importance of attention to the smallest levels of government who are tasked with putting sustainable livelihoods initiatives into practice in relation to people’s daily lives

PHENOLIC COMPOUNDS FROM CALLISTEMON CITRINUS LEAVES AND STEMS

In the search for bioactive constituents from Vietnamese plants,  the leaves and stems of Callistemon citrinus (Curtis) Skeels were selected for chemical investigation. Phytochemical analysis of plant led to the isolation of eight phenolic compounds including two flavonoids (eucalyptine (1) and 8-demethyleucalyptine (2)), two alcohols (blumenol A (3), n-tetratriacontanol (4)), three benzoic acid derivatives (acid gallic (5), methyl gallate (6) protocatechuic acid (7)), one sterol (b-sitosterol (8)), and along with one sesquiterpene (2,6,10-bisabolatriene (9)). The structures of the natural compounds were determined by spectroscopic evidences including 1D- and 2D-NMR and ESI-MS