Covalent binding studies on the 14C-labeled antitumour compound 2,5-bis(1-aziridinyl)-1,4-benzoquinone. Involvement of semiquinone radical in binding to DNA, and binding to proteins and bacterial macromolecules in situ

2,5-Bis(1-aziridinyl)-1,4-benzoquinone (BABQ) is a compound from which several antitumour drugs are derived, such as Trenimone, Carboquone and Diaziquone (AZQ). The mechanism of DNA binding of BABQ was studied using 14C-labeled BABQ and is in agreement with reduction of the quinone moiety and protonation of the aziridine ring, followed by ring opening and alkylation. The one-electron reduced (semiquinone) form of BABQ alkylates DNA more efficiently than two-electron reduced or non reduced BABQ. Covalent binding to polynucleotides did not unambiguously reveal preference for binding to specific DNA bases. Attempts to elucidate further the molecular structure of DNA adducts by isolation of modified nucleosides from enzymatic digests of reacted DNA failed because of instability of the DNA adducts. The mechanism of covalent binding to protein (bovine serum albumin, BSA) appeared to be completely different from that of covalent binding to DNA. Binding of BABQ to BSA was not enhanced by reduction of the compound and was pH dependent in a way that is opposite to that of DNA alkylation. Glutathione inhibits binding of BABQ to BSA and forms adducts with BABQ in a similar pH dependence as the protein binding. The aziridine group therefore does not seem to be involved in the alkylation of BSA. Incubation of intact E. coli cells, which endogenously reduce BABQ, resulted in binding to both DNA and RNA, but also appreciable protein binding was observed

Collecting Contextual Information About a DDoS Attack Event Using Google Alerts

Distributed Denial of Service (DDoS) attacks may lead to massive economic damages to victims. In most cases, the damage caused is dictated by the circumstances surrounding the attack (i.e. context). One of the ways of collecting information on the context of an attack can be by using the online articles written about the attack. In this poster, we introduce a dataset collected using Google Alerts that provides contextual information related DDoS attacks. The goal of the poster is to invite other researchers for collaboratio

RAPD for the typing of coagulase-negative staphylococci implicated in catheter-related bloodstream infection

Objectives: A rapid random amplification of polymorphic DNA (RAPD) technique was developed to distinguish between strains of coagulase-negative staphylococci (CoNS) involved in central venous catheter (CVC)-related bloodstream infection. Its performance was compared with that of pulsed-field gel electrophoresis (PFGE). Methods: Patients at the University Hospital Birmingham NHS Foundation Trust, U.K. who underwent stem cell transplantation and were diagnosed with CVC-related bloodstream infection due to CoNS whilst on the bone marrow transplant unit were studied. Isolates of CoNS were genotyped by PFGE and RAPD, the latter employing a single primer and a simple DNA extraction method. Results: Both RAPD and PFGE were highly discriminatory (Simpson's diversity index, 0.96 and 0.99, respectively). Within the 49 isolates obtained from blood cultures of 33 patients, 20 distinct strains were identified by PFGE and 25 by RAPD. Of the 25 strains identified by RAPD, nine clusters of CoNS contained isolates from multiple patients, suggesting limited nosocomial spread. However, there was no significant association between time of inpatient stay and infection due to any particular strain. Conclusion: The RAPD technique presented allows CoNS strains to be genotyped with high discrimination within 4 h, facilitating real-time epidemiological investigations. In this study, no single strain of CoNS was associated with a significant number of CVC-related bloodstream infections. © 2005 Published by Elsevier Ltd on behalf of the British Infection Society

Quality of Service and Service Provisioning on a Competitive Market

The objective of this paper is to provide an economic and commercial context for QoS research in open distributed environments. The analyses are based on a telecommunications value chain model. The model is used to define possible roles for telecommunications companies, migrating from traditional telephony network operators towards privatised ICT companies in a new economy. Based on these developments, we advocate R&D activities aiming at standardised concepts and engineering principles to establish and control QoS in open distributed environments

Assessing Network Operator Actions to Enhance Digital Sovereignty and Strengthen Network Resilience:A Longitudinal Analysis during the Russia-Ukraine Conflict

We conduct longitudinal and temporal analyses on active DNS measurement data to investigate how the Russia-Ukraine conflict impacted the network infrastructures supporting domain names under ICANN’s CZDS new gTLDs. Our findings revealed changes in the physical locations of network infrastructures, utilization of managed DNS services, infrastructure redundancy, and distribution, which started right after the first reported Russian military movements in February 2022. We also found that domains from different countries had varying location preferences when moving their hosting infrastructure. These observed changes suggest that network operators took proactive measures in anticipation of an armed conflict to promote resilience and protect the sovereignty of their networks in response to the conflict

Dyonic Membranes

We present dyonic multi-membrane solutions of the N=2 D=8 supergravity theory that serves as the effective field theory of the $T^2$-compactified type II superstring theory. The `electric' charge is fractional for generic asymptotic values of an axion field, as for D=4 dyons. These membrane solutions are supersymmetric, saturate a Bogomolnyi bound, fill out orbits of an $Sl(2;\Z)$ subgroup of the type II D=8 T-duality group, and are non-singular when considered as solutions of $T^3$-compactified D=11 supergravity. On $K_3$ compactification to D=4, the conjectured type II/heterotic equivalence allows the $Sl(2;\Z)$ group to be reinterpreted as the S-duality group of the toroidally compactified heterotic string and the dyonic membranes wrapped around homology two-cycles of $K_3$ as S-duals of perturbative heterotic string states.Comment: Phyzzx. 27 pp. Additional para. added to introductio

Measuring Malware Detection Capability for Security Decision Making

Organizations face an urgent need to bolster their cybersecurity defenses against the rising threat of ransomware. Implementing advanced antivirus and antimalware tools is crucial for proactive identification and mitigation of malicious software. However, adversaries constantly refine malware to evade detection increasing the complexity of the threat. Hence, developing an effective strategy is nontrivial. To address this challenge, this study conducts various analyses on scan results of publicly shared malware samples. Utilizing metadata from 635K samples sourced from MalwareBazaar and scan results from VirusTotal, we assign family labels using AVClass. Additionally, we examinea 90-day longitudinal dataset alongside the main dataset. Our findings demonstrate that while over 60% of scanner engines detect 67% of samples, certain malware families consistently exhibit lower detection rates. Detection capability improves over time, particularly within the initial 30 days, but remainsinadequate for specific families. Furthermore, we observe that some scanner engines demonstrate nearly flawless detection capability across all malware families, while the majority struggle with efficiently detecting certain types. Moreover, we performed Monte Carlo simulations and revealed that employing multiple scanner engines substantially enhances detection capability, with 3 to 7 scanners being optimal. Finally, simulation analysis in a case study highlights thesignificant impact of hard-to-detect malware on risk and performance, underscoring the importance of effective malware strategies

Tachyon Dynamics and the Effective Action Approximation

Recently effective actions have been extensively used to describe tachyon condensation in string theory. While the various effective actions which have appeared in the literature have very similar properties for static configurations, they differ for time-dependent tachyons. In this paper we discuss general properties of non-linear effective Lagrangians which are first order in derivatives. In particular we show that some observed properties, such as asymptotically vanishing pressure, are rather generic features, although the quantative features differ. On the other hand we argue that certain features of marginal tachyon profiles are beyond the reach of any first order Lagrangian description. We also point out that an effective action, proposed earlier, captures the dynamics of tachyons well.Comment: References added and confusing reference clarifie

Comments on D-brane Dynamics Near NS5-Branes

We study the properties of a D-brane in the presence of $k$ NS5 branes. The Dirac-Born-Infeld action describing the dynamics of this D-brane is very similar to that of a non-BPS D-brane in ten dimensions. As the D-brane approaches the fivebranes, its equation of state approaches that of a pressureless fluid. In non-BPS D-brane case this is considered as an evidence for the decay of the D-brane into ``tachyon matter''. We show that in our case similar behavior is the consequence of the motion of the D-brane. In particular in the rest frame of the moving D-brane the equation of state is that of a usual D-brane, for which the pressure is equal to the energy density. We also compute the total cross-section for the decay of the D-brane into closed string modes and show that the emitted energy has a power like divergence for $D0$, $D1$ and $D2$ branes, while converges for higher dimensional D-branes. We also speculate on the possibility that the infalling D-brane describes a decaying defect in six dimensional Little String Theory.Comment: 18 pages, latex, references added, minor change