On fast and accurate detection of unauthorized wireless access points using clock skews

Journal ArticleWe explore the use of clock skew of a wireless local area network access point (AP) as its fingerprint to detect unauthorized APs quickly and accurately. The main goal behind using clock skews is to overcome one of the major limitations of existing solutions-the inability to effectively detect Medium Access Control (MAC) address spoofing. We calculate the clock skew of an AP from the IEEE 802.11 Time Synchronization Function (TSF) time stamps sent out in the beacon/probe response frames. We use two different methods for this purpose-one based on linear programming and the other based on least-square fit. We supplement these methods with a heuristic for differentiating original packets from those sent by the fake APs. We collect TSF time stamp data from several APs in three different residential settings. Using our measurement data as well as data obtained from a large conference setting, we find that clock skews remain consistent over time for the same AP but vary significantly across APs. Furthermore, we improve the resolution of received time stamp of the frames and show that with this enhancement, our methodology can find clock skews very quickly, using 50-100 packets in most of the cases. We also discuss and quantify the impact of various external factors including temperature variation, virtualization, clock source selection, and NTP synchronization on clock skews. Our results indicate that the use of clock skews appears to be an efficient and robust method for detecting fake APs in wireless local area networks

Catastrophic consequences of the enormous use of hydroxychloroquine during COVID era on liver and kidney of male albino rats: an in-vivo study

Background: Hydroxychloroquine (HCQ) is mainly used for the treatment of malaria but during COVID trial, it was used against coronavirus though no history of the drug is known against SARS COV 2 or any other respiratory ailment. Many case studies showed the adverse effects on liver and kidney in many patients after the exposure of HCQ. The main aim of this study is to know the effect of HCQ drug on the liver and kidney of male albino rat at a range of human equivalent dose that was given during COVID period. Methods: After institutional animal ethics committee (IAEC) approval, ten male albino rats were obtained and divided into two groups-control and treated. Treated groups receives HCQ through oral gavage for six days and then serum, tissue enzymes and total serum bilirubin were measured. Histopathological study was done from liver and kidney tissue. After that statistical analysis was done. Results: We found significant increase in enzymes glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT) and alkaline phosphatase (ALP) in the HCQ-treated rats than in control and this signifies that there might be damages that occurred in liver and kidney. Increased level of bilirubin in HCQ-treated rats indicate hyperbilirubinemia and may be a sign of jaundice or any other hepatic disorder. From histopathological identification we also found liver and kidney tissues got damaged due to exposure of HCQ. Conclusions: From this study, we can conclude that the exposure of this drug might have led to the impaired function of organs that could have potentiated their ill fate

Effect of Village-wide Use of Long-Lasting Insecticidal Nets on Visceral Leishmaniasis Vectors in India and Nepal: A Cluster Randomized Trial

Visceral leishmaniasis (VL) is a vector-borne disease causing at least 60,000 deaths each year amongst an estimated half million cases, and until recently there have been no significant initiatives to reduce this burden. However, in 2005, the governments of India, Bangladesh and Nepal signed a memorandum of understanding at the World Health Assembly in Geneva for the elimination of the disease by 2015. In the absence of an effective vaccine, the program will rely on the active detection and prompt treatment of cases throughout the endemic region, combined with a recurrent indoor residual spraying (IRS) of all villages at risk. Vector control programs based on IRS are notorious for failing to maintain comprehensive spray coverage over time owing to logistical problems and lack of compliance by householders. Long-lasting insecticidal nets (LNs) have been postulated as an alternative or complement to IRS. Here we describe how comprehensive coverage of LN in trial communities reduced the indoor density of sand flies by 25% compared to communities without LNs. This provides an indication that LNs could be usefully deployed as a component of the VL control program in the Indian subcontinent

New Insights into the Bacterial Fitness-Associated Mechanisms Revealed by the Characterization of Large Plasmids of an Avian Pathogenic E. coli

Extra-intestinal pathogenic E. coli (ExPEC), including avian pathogenic E. coli (APEC), pose a considerable threat to both human and animal health, with illness causing substantial economic loss. APEC strain χ7122 (O78∶K80∶H9), containing three large plasmids [pChi7122-1 (IncFIB/FIIA-FIC), pChi7122-2 (IncFII), and pChi7122-3 (IncI(2))]; and a small plasmid pChi7122-4 (ColE2-like), has been used for many years as a model strain to study the molecular mechanisms of ExPEC pathogenicity and zoonotic potential. We previously sequenced and characterized the plasmid pChi7122-1 and determined its importance in systemic APEC infection; however the roles of the other pChi7122 plasmids were still ambiguous. Herein we present the sequence of the remaining pChi7122 plasmids, confirming that pChi7122-2 and pChi7122-3 encode an ABC iron transport system (eitABCD) and a putative type IV fimbriae respectively, whereas pChi7122-4 is a cryptic plasmid. New features were also identified, including a gene cluster on pChi7122-2 that is not present in other E. coli strains but is found in Salmonella serovars and is predicted to encode the sugars catabolic pathways. In vitro evaluation of the APEC χ7122 derivative strains with the three large plasmids, either individually or in combinations, provided new insights into the role of plasmids in biofilm formation, bile and acid tolerance, and the interaction of E. coli strains with 3-D cultures of intestinal epithelial cells. In this study, we show that the nature and combinations of plasmids, as well as the background of the host strains, have an effect on these phenomena. Our data reveal new insights into the role of extra-chromosomal sequences in fitness and diversity of ExPEC in their phenotypes

On fast and accurate detection of unauthorized wireless access points using clock skews

We explore the use of clock skew of a wireless local area network access point (AP) as its fingerprint to detect unauthorized APs quickly and accurately. The main goal behind using clock skews is to overcome one of the major limitations of existing solutions- the inability to effectively detect Medium Access Control (MAC) address spoofing. We calculate the clock skew of an AP from the IEEE 802.11 Time Synchronization Function (TSF) timestamps sent out in the beacon/probe response frames. We use two different methods for this purpose- one based on linear programming and the other based on least square fit. We supplement these methods with a heuristic for differentiating original packets from those sent by the fake APs. We collect TSF timestamp data from several APs in two different residential settings. Using our measurement data as well as data obtained from a large conference setting, we find that clock skews remain consistent over time for the same AP but vary significantly across APs. Furthermore, we improve the resolution of received timestamp of the frames and show that with this enhancement our methodology can find clock skews very quickly, using 50-100 packets in most of the cases. We also discuss and quantify the impact of various external factors including temperature variation, virtualization, and NTP synchronization on clock skews. Our results indicate that the use of clock skews appears to be an efficient and robust method for detecting fake APs in wireless local area networks

Acylation of aromatic compounds using moisture insensitive mesoporous Si-MCM-41 supported Ga<SUB>2</SUB>O<SUB>3</SUB> catalyst

Mesoporous Si-MCM-41 supported Ga2O3 is a highly active catalyst for the acylation of aromatic compounds with different acyl chlorides. Moreover, this catalyst is not deactivated by water and hence does not require moisture-free reaction conditions

Benzylation of benzene and substituted benzenes by benzyl chloride over InCl<SUB>3</SUB>, GaCl<SUB>3</SUB>, FeCl<SUB>3</SUB> and ZnCl<SUB>2</SUB> supported on clays and Si-MCM-41

Liquid phase benzylation of benzene by benzyl chloride to diphenyl methane over InCl3, GaCl3, FeCl3 and ZnCl2 supported on commercial clays (viz. Montmorillonite-K10, Montmorillonite-KSF and Kaolin) or on high silica mesoporous MCM-41 (at 60, 70 and 80 &#176;C) has been investigated. The supported InCl3, GaCl3 and FeCl3 showed high activity for the benzylation of benzene. The redox function created due to the impregnation of the clays or Si-MCM-41 by InCl3, GaCl3, FeCl3 or ZnCl2 seems to play a very important role in the benzylation process. Among the catalysts, the InCl3/Mont.-K10 showed both high activity and high selectivity for the benzylation. The activity of this catalyst for the benzylation of different aromatic compounds is in the following order: benzene&gt;toluene&gt;mesitylene&gt;anisole. The InCl3 (or GaCl3)/Mont.-K10 (or Si-MCM-41) catalyst showed high benzene benzylation activity even in the presence of moisture in the reaction mixture. The catalyst can also be reused in the benzylation for several times. Kinetics of the benzene benzylation (using excess of benzene) over the supported metal chloride catalysts have also been thoroughly investigated. A plausible reaction mechanism for the benzylation over the supported metal chloride catalysts is proposed

Highly active and low moisture sensitive supported thallium oxide catalysts for Friedal-Crafts type benzylation and acylation reactions: Strong thallium oxide - support interactions

Liquid-phase benzylation of benzene by benzyl chloride (at 80° C) over basic TlOx (without support) and supported TlOx prepared using different low and high surface area commonly used catalyst carriers has been investigated. The catalysts have been characterized by their surface area and also by XRD, FTIR, and XPS. Strong TlOx-support interactions (which are chemical in nature) have been observed for the catalysts prepared using high surface area (HS), supports, such as Si-MCM-41, silica gel (HS), silica-alumina (HS), alumina (HS), and zirconia (HS), which have surface hydroxyl groups. These catalysts are found to be inactive for benzene benzylation or benzoylation reaction. However, the TlOx supported on sintered low surface area (LS) macroporous catalyst carriers [viz. zirconia (LS), silica (LS), and silica-alumina (LS)], which have no surface hydroxyl groups, showed high benzene benzylation activity. TlOx/zirconia (LS) is a highly promising catalyst for both the benzylation and acylation of benzene and other aromatic compounds and it shows high activity, even in the presence of moisture. The activity of this catalyst for the benzylation of benzene and substituted benzenes is in the following order: benzene &gt; toluene &gt; p-xylene &gt; anisole. The induction period for the benzylation and acylation reactions over the catalyst, however, depends strongly on the moisture present in the catalyst and/or in the reaction mixture. The induction period is drastically reduced by the HCl gas pretreatment of the catalyst before the benzylation or acylation reaction. Only the catalyst that contains Tl2O3 shows activity for the benzylation and acylation reactions. A redox mechanism for these reactions over the supported TlOx catalysts has been proposed

Benzoylation of benzene and substituted benzenes by benzoyl chloride over In<SUB>2</SUB>O<SUB>3</SUB>/Si-MCM-41 catalyst

Liquid phase benzoylation of benzene by benzoyl chloride over In2O3, Ga2O3 and ZnO supported on high silica mesoporous MCM-41 at 80 ° C has been investigated. The supported In2O3, Ga2O3 and ZnO catalysts showed high activity for the benzoylation of benzene. The redox function and activation of aromatic substrate by the supported basic In2O3 and amphoteric Ga2O3 or ZnO seem to play a very important role in the benzoylation process. Among the catalysts, the In2O3/Si-MCM-41 showed the highest activity for the benzoylation of benzene. The activity of this catalyst for the benzoylation of benzene and substituted benzenes is in the following order: anisole&gt;mesitylene&gt;p-xylene&gt;toluene&gt;benzene. The In2O3 (or Ga2O3)/Si-MCM-41 showed high benzoylation activity of benzene even in the presence of appreciable amounts of moisture in the reaction mixture. Solvent and its nature (polar or non-polar) also play important role in the benzoylation over the supported In2O3 catalyst