The toxic leadership point out damaging attitudes and behaviours which can affect leaders’ person... more The toxic leadership point out damaging attitudes and behaviours which can affect leaders’ personal traits resulting severe damage to the organization and its subordinates. Given the multinational environment from a theatre of operations, what might be toxic for the military in one country might be accepted in another one, taking into consideration the discrepancies between cultures. No matter their cultural background or their national particularities, the toxic leaders reduce the effectiveness of the organization and of it’s operations. This article wants to highlight, from an analytical approach, the existing types of toxic leaders and their impact to the military organization in Afghanistan theatre of operations.
Abstract. This paper presents a theory of testing for processes calculi which have broadcast as b... more Abstract. This paper presents a theory of testing for processes calculi which have broadcast as basic communication primitive. Firstly, we justify the necessity of an alternative theory to bisimulations for broadcasting calculi. Then, we remind CBS without message passing and bπ-calculus, and we adapt the definitions of may testing and must testing in the framework of broadcasting calculi. Finally, we give a direct characterization for these pre-orders. 1
Formal Techniques for Distributed Objects, Components, and Systems, 2019
Constant-time programming is a countermeasure to prevent cache based attacks where programs shoul... more Constant-time programming is a countermeasure to prevent cache based attacks where programs should not perform memory accesses that depend on secrets. In some cases this policy can be safely relaxed if one can prove that the program does not leak more information than the public outputs of the computation. We propose a novel approach for verifying constant-time programming based on a new information flow property, called output-sensitive noninterference. Noninterference states that a public observer cannot learn anything about the private data. Since real systems need to intentionally declassify some information, this property is too strong in practice. In order to take into account public outputs we proceed as follows: instead of using complex explicit declassification policies, we partition variables in three sets: input, output and leakage variables. Then, we propose a typing system to statically check that leakage variables do not leak more information about the secret inputs than the public normal output. The novelty of our approach is that we track the dependence of leakage variables with respect not only to the initial values of input variables (as in classical approaches for noninterference), but taking also into account the final values of output variables. We adapted this approach to LLVM IR and we developed a prototype to verify LLVM implementations.
Two ZnO materials of spherical hierarchical morphologies, with hollow (ZnO HS) and solid cores (Z... more Two ZnO materials of spherical hierarchical morphologies, with hollow (ZnO HS) and solid cores (ZnO SS), were obtained through the hydrolysis of zinc acetylacetonate in 1,4butanediol. The nature of the defects and surface reactivity for the two ZnO materials were investigated through photoluminescence (PL), X-ray photoelectron (XPS) and electronic paramagnetic resonance (EPR) spectroscopy proving the coexistence of shallow and deep defects and, also, the presence of polyol by-products adsorbed on the outer layers of the ZnO samples. The EPR spectroscopy coupled with spin-trapping technique showed that the surface of the ZnO samples generates reactive oxygen species (ROS) like hydroxyl (• OH) and singlet oxygen (1 O 2) as well as carbon-centered radicals. The ZnO materials exhibited a wide spectrum of antimicrobial activity, being active against Gram positive, Gram negative and fungi strains, both in planktonic and, more important, adherent growth state. The decrease of antimicrobial efficiency in the presence of a ROS-scavenger (mannitol) and the decrease of the cell viability with ROS level, suggests that one of the mechanism that governs both the antimicrobial and cytotoxic activity on human liver cells is ROS mediated. However, at active antimicrobial concentrations, the biocompatibility of the tested materials is very good.
In this paper we address the problem of the expressive po-wer of point-to-point communication to ... more In this paper we address the problem of the expressive po-wer of point-to-point communication to implement broadcast communication. We demonstrate that point-to-point communication as in CCS [M89] is too asynchronous to implement broadcast ...
Proceedings 15th International Parallel and Distributed Processing Symposium. IPDPS 2001
This paper presents a process calculus for reconfigurable communicating systems which has broadca... more This paper presents a process calculus for reconfigurable communicating systems which has broadcast as basic communication primitive, and we provide an operational semantics for this calculus. We illustrate the calculus through some examples, and we propose three behavioural equivalences for reasoning about systems of broadcasting processes, namely, barbed equivalence, step-equivalence and labelled bisimilarity. An important result, is that all these relations coincide, providing different ways to study the equivalence/non-equivalence of two systems. Then, we provide a direct characterization for the strong congruence relation induced by these equivalences. Finally, we give a complete axiomatisation for strong congruence.
In this paper we investigate several decision problems for parallel communicating grammar systems... more In this paper we investigate several decision problems for parallel communicating grammar systems: the enabling, circularity, centralizing, conflict-freeness, boundedness, membership, equivalence, inclusion, emptiness and finiteness problems. The first five problems are shown to be decidable for context-free PCS's but undecidable for the context-sensitive case. The last five problems are only studied for the context-sensitive case and they are shown to be undecidable.
The crystal structures of two pentacyanido(L) ferrate(III) complexes, [P(C6H5)4]2[Fe(CN)5(prz)]·4... more The crystal structures of two pentacyanido(L) ferrate(III) complexes, [P(C6H5)4]2[Fe(CN)5(prz)]·4H2O 1, [P(C6H5)4]2[Fe(CN)5(4,4′-bipy)]·3H2O 2, have been solved. Within the two complex anions the iron atoms are hexacoordinated by five cyanido ligands, the sixth position being occupied by the nitrogen atom arising from pyrazine and, respectively, 4,4′-bipyridine. The electrochemical properties of compounds 1, 2 and of the azido derivative, (Ph4As)2[Na(H2O)4][Fe(CN)5(N3)] 3, have been
... Dumbrava Rosie 23, 020464 Bucharest, Romania. b School of Chemistry, University of Manchester... more ... Dumbrava Rosie 23, 020464 Bucharest, Romania. b School of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, UK. ... The structures were solved by direct methods and refined by full-matrix least squares techniques based on F 2 . The non-H atoms were ...
A trinuclear copper(II) complex, [Cu3(2,5-pydc)2(Me5dien)2(BF4)2(H2O)2]·H2O 1, has been construct... more A trinuclear copper(II) complex, [Cu3(2,5-pydc)2(Me5dien)2(BF4)2(H2O)2]·H2O 1, has been constructed from 2,5-pyridine-dicarboxylato bridges (2,5-pydc2−) and N,N,N′,N″,N″-pentamethyl-diethylenetriamine (Me5dien) acting as a blocking ligand. The copper ions, within the centrosymmetric trinuclear cations, are connected by two 2,5-pydc2− bridges, with an intramolecular Cu···Cu separation of 8.432Å. The central copper ion exhibits an elongated octahedral geometry, with semicoordinated (BF4-) ions, while the terminal ones are
The reactions of pyrazole (Hpz) with some copper(II) carboxylates in the presence of water yield ... more The reactions of pyrazole (Hpz) with some copper(II) carboxylates in the presence of water yield trinuclear copper derivatives characterized by the triangular core [Cu3mu3-OH)(mu-pz)3(RCOO)2] (R = H, C2H5, C3H7). Copper(II) formate gives [Cu3(mu3-OH)(mu-pz)3(HCOO)2(Hpz)2] (1), whereas copper propionate and butyrate afford [Cu3(mu3-OH)(mu-pz)3(C2H5COO)2(EtOH)] (2) and [Cu3(mu3-OH)(mu-pz)3(C3H7COO)2(MeOH)(H2O)] (3), respectively, both containing solvent molecules coordinated to copper atoms. Magnetic susceptibilities are consistent with a single unpaired electron for each trinuclear unit of 1-3, and EPR measurements indicate that higher spin states, generated by exchange coupling between copper atoms, may be populated at room temperature. Density-functional calculations provide the description of the electronic structures of 1-3, allowing, at the same time, the assignment of their UV-vis absorption spectra. X-ray molecular structure determinations show that triangular trinuclear units of 1 are connected to each other through single formate bridges, forming one-dimensional (1D) zigzag coordination polymers, whereas in 2 and 3, two oxygen atoms of two carboxylate ions doubly bridge two copper atoms of different triangles, thus generating hexanuclear units. Moreover, in 2, two other propionate ions link together two hexanuclear units yielding a 12-membered cycle and giving rise to 1D coordination polymers. The supramolecular assemblies of 1-3 are compared to that of the previously reported trinuclear triangular copper(II) derivative [Cu3(mu3-OH)(mu-pz)3(CH3COO)2(Hpz)] (A), where a two-dimensional (2D) coordination polymer is present. The reactions of 3,5-dimethylpyrazole (Hpz) with copper(II) carboxylates in the same conditions yield 1:2 Cu(RCOO)2/Hpz adducts.
In this paper we present a novel multicast streaming architecture based on a peer-to-peer overlay... more In this paper we present a novel multicast streaming architecture based on a peer-to-peer overlay with a balanced tree structure. The overlay is maintained in a fully decentralized manner. The system has been fully implemented and evaluated under real network conditions. The results clearly show the improvements brought by our system over a classical client-server architecture.
This paper presents a theory of testing for processes calculi which have broadcast as basic commu... more This paper presents a theory of testing for processes calculi which have broadcast as basic communication primitive. Firstly, we justify the necessity of an alternative theory to bisimulations for broadcasting calculi. Then, we remind CBS without message passing and bπ-calculus, and we adapt the definitions of may testing and must testing in the framework of broadcasting calculi. Finally, we give a direct characterization for these pre-orders.
Eva Jaho, Ioannis Koukoutsidis*, Siyu Tang, Ioannis Stavrakakis, and Piet Van Mieghem ... Na... more Eva Jaho, Ioannis Koukoutsidis*, Siyu Tang, Ioannis Stavrakakis, and Piet Van Mieghem ... National & Kapodistrian University of Athens, Dept. Informatics and Telecommunications, Ilissia, 157 84 Athens, Greece, E-mail: {ejaho,ioannis}@di.uoa.gr
The toxic leadership point out damaging attitudes and behaviours which can affect leaders’ person... more The toxic leadership point out damaging attitudes and behaviours which can affect leaders’ personal traits resulting severe damage to the organization and its subordinates. Given the multinational environment from a theatre of operations, what might be toxic for the military in one country might be accepted in another one, taking into consideration the discrepancies between cultures. No matter their cultural background or their national particularities, the toxic leaders reduce the effectiveness of the organization and of it’s operations. This article wants to highlight, from an analytical approach, the existing types of toxic leaders and their impact to the military organization in Afghanistan theatre of operations.
Abstract. This paper presents a theory of testing for processes calculi which have broadcast as b... more Abstract. This paper presents a theory of testing for processes calculi which have broadcast as basic communication primitive. Firstly, we justify the necessity of an alternative theory to bisimulations for broadcasting calculi. Then, we remind CBS without message passing and bπ-calculus, and we adapt the definitions of may testing and must testing in the framework of broadcasting calculi. Finally, we give a direct characterization for these pre-orders. 1
Formal Techniques for Distributed Objects, Components, and Systems, 2019
Constant-time programming is a countermeasure to prevent cache based attacks where programs shoul... more Constant-time programming is a countermeasure to prevent cache based attacks where programs should not perform memory accesses that depend on secrets. In some cases this policy can be safely relaxed if one can prove that the program does not leak more information than the public outputs of the computation. We propose a novel approach for verifying constant-time programming based on a new information flow property, called output-sensitive noninterference. Noninterference states that a public observer cannot learn anything about the private data. Since real systems need to intentionally declassify some information, this property is too strong in practice. In order to take into account public outputs we proceed as follows: instead of using complex explicit declassification policies, we partition variables in three sets: input, output and leakage variables. Then, we propose a typing system to statically check that leakage variables do not leak more information about the secret inputs than the public normal output. The novelty of our approach is that we track the dependence of leakage variables with respect not only to the initial values of input variables (as in classical approaches for noninterference), but taking also into account the final values of output variables. We adapted this approach to LLVM IR and we developed a prototype to verify LLVM implementations.
Two ZnO materials of spherical hierarchical morphologies, with hollow (ZnO HS) and solid cores (Z... more Two ZnO materials of spherical hierarchical morphologies, with hollow (ZnO HS) and solid cores (ZnO SS), were obtained through the hydrolysis of zinc acetylacetonate in 1,4butanediol. The nature of the defects and surface reactivity for the two ZnO materials were investigated through photoluminescence (PL), X-ray photoelectron (XPS) and electronic paramagnetic resonance (EPR) spectroscopy proving the coexistence of shallow and deep defects and, also, the presence of polyol by-products adsorbed on the outer layers of the ZnO samples. The EPR spectroscopy coupled with spin-trapping technique showed that the surface of the ZnO samples generates reactive oxygen species (ROS) like hydroxyl (• OH) and singlet oxygen (1 O 2) as well as carbon-centered radicals. The ZnO materials exhibited a wide spectrum of antimicrobial activity, being active against Gram positive, Gram negative and fungi strains, both in planktonic and, more important, adherent growth state. The decrease of antimicrobial efficiency in the presence of a ROS-scavenger (mannitol) and the decrease of the cell viability with ROS level, suggests that one of the mechanism that governs both the antimicrobial and cytotoxic activity on human liver cells is ROS mediated. However, at active antimicrobial concentrations, the biocompatibility of the tested materials is very good.
In this paper we address the problem of the expressive po-wer of point-to-point communication to ... more In this paper we address the problem of the expressive po-wer of point-to-point communication to implement broadcast communication. We demonstrate that point-to-point communication as in CCS [M89] is too asynchronous to implement broadcast ...
Proceedings 15th International Parallel and Distributed Processing Symposium. IPDPS 2001
This paper presents a process calculus for reconfigurable communicating systems which has broadca... more This paper presents a process calculus for reconfigurable communicating systems which has broadcast as basic communication primitive, and we provide an operational semantics for this calculus. We illustrate the calculus through some examples, and we propose three behavioural equivalences for reasoning about systems of broadcasting processes, namely, barbed equivalence, step-equivalence and labelled bisimilarity. An important result, is that all these relations coincide, providing different ways to study the equivalence/non-equivalence of two systems. Then, we provide a direct characterization for the strong congruence relation induced by these equivalences. Finally, we give a complete axiomatisation for strong congruence.
In this paper we investigate several decision problems for parallel communicating grammar systems... more In this paper we investigate several decision problems for parallel communicating grammar systems: the enabling, circularity, centralizing, conflict-freeness, boundedness, membership, equivalence, inclusion, emptiness and finiteness problems. The first five problems are shown to be decidable for context-free PCS's but undecidable for the context-sensitive case. The last five problems are only studied for the context-sensitive case and they are shown to be undecidable.
The crystal structures of two pentacyanido(L) ferrate(III) complexes, [P(C6H5)4]2[Fe(CN)5(prz)]·4... more The crystal structures of two pentacyanido(L) ferrate(III) complexes, [P(C6H5)4]2[Fe(CN)5(prz)]·4H2O 1, [P(C6H5)4]2[Fe(CN)5(4,4′-bipy)]·3H2O 2, have been solved. Within the two complex anions the iron atoms are hexacoordinated by five cyanido ligands, the sixth position being occupied by the nitrogen atom arising from pyrazine and, respectively, 4,4′-bipyridine. The electrochemical properties of compounds 1, 2 and of the azido derivative, (Ph4As)2[Na(H2O)4][Fe(CN)5(N3)] 3, have been
... Dumbrava Rosie 23, 020464 Bucharest, Romania. b School of Chemistry, University of Manchester... more ... Dumbrava Rosie 23, 020464 Bucharest, Romania. b School of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, UK. ... The structures were solved by direct methods and refined by full-matrix least squares techniques based on F 2 . The non-H atoms were ...
A trinuclear copper(II) complex, [Cu3(2,5-pydc)2(Me5dien)2(BF4)2(H2O)2]·H2O 1, has been construct... more A trinuclear copper(II) complex, [Cu3(2,5-pydc)2(Me5dien)2(BF4)2(H2O)2]·H2O 1, has been constructed from 2,5-pyridine-dicarboxylato bridges (2,5-pydc2−) and N,N,N′,N″,N″-pentamethyl-diethylenetriamine (Me5dien) acting as a blocking ligand. The copper ions, within the centrosymmetric trinuclear cations, are connected by two 2,5-pydc2− bridges, with an intramolecular Cu···Cu separation of 8.432Å. The central copper ion exhibits an elongated octahedral geometry, with semicoordinated (BF4-) ions, while the terminal ones are
The reactions of pyrazole (Hpz) with some copper(II) carboxylates in the presence of water yield ... more The reactions of pyrazole (Hpz) with some copper(II) carboxylates in the presence of water yield trinuclear copper derivatives characterized by the triangular core [Cu3mu3-OH)(mu-pz)3(RCOO)2] (R = H, C2H5, C3H7). Copper(II) formate gives [Cu3(mu3-OH)(mu-pz)3(HCOO)2(Hpz)2] (1), whereas copper propionate and butyrate afford [Cu3(mu3-OH)(mu-pz)3(C2H5COO)2(EtOH)] (2) and [Cu3(mu3-OH)(mu-pz)3(C3H7COO)2(MeOH)(H2O)] (3), respectively, both containing solvent molecules coordinated to copper atoms. Magnetic susceptibilities are consistent with a single unpaired electron for each trinuclear unit of 1-3, and EPR measurements indicate that higher spin states, generated by exchange coupling between copper atoms, may be populated at room temperature. Density-functional calculations provide the description of the electronic structures of 1-3, allowing, at the same time, the assignment of their UV-vis absorption spectra. X-ray molecular structure determinations show that triangular trinuclear units of 1 are connected to each other through single formate bridges, forming one-dimensional (1D) zigzag coordination polymers, whereas in 2 and 3, two oxygen atoms of two carboxylate ions doubly bridge two copper atoms of different triangles, thus generating hexanuclear units. Moreover, in 2, two other propionate ions link together two hexanuclear units yielding a 12-membered cycle and giving rise to 1D coordination polymers. The supramolecular assemblies of 1-3 are compared to that of the previously reported trinuclear triangular copper(II) derivative [Cu3(mu3-OH)(mu-pz)3(CH3COO)2(Hpz)] (A), where a two-dimensional (2D) coordination polymer is present. The reactions of 3,5-dimethylpyrazole (Hpz) with copper(II) carboxylates in the same conditions yield 1:2 Cu(RCOO)2/Hpz adducts.
In this paper we present a novel multicast streaming architecture based on a peer-to-peer overlay... more In this paper we present a novel multicast streaming architecture based on a peer-to-peer overlay with a balanced tree structure. The overlay is maintained in a fully decentralized manner. The system has been fully implemented and evaluated under real network conditions. The results clearly show the improvements brought by our system over a classical client-server architecture.
This paper presents a theory of testing for processes calculi which have broadcast as basic commu... more This paper presents a theory of testing for processes calculi which have broadcast as basic communication primitive. Firstly, we justify the necessity of an alternative theory to bisimulations for broadcasting calculi. Then, we remind CBS without message passing and bπ-calculus, and we adapt the definitions of may testing and must testing in the framework of broadcasting calculi. Finally, we give a direct characterization for these pre-orders.
Eva Jaho, Ioannis Koukoutsidis*, Siyu Tang, Ioannis Stavrakakis, and Piet Van Mieghem ... Na... more Eva Jaho, Ioannis Koukoutsidis*, Siyu Tang, Ioannis Stavrakakis, and Piet Van Mieghem ... National & Kapodistrian University of Athens, Dept. Informatics and Telecommunications, Ilissia, 157 84 Athens, Greece, E-mail: {ejaho,ioannis}@di.uoa.gr
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