The Design, Testing, and Analysis of a Constant Jammer for the Bluetooth Low Energy (BLE) Wireless Communication Protocol

The decreasing cost of web-enabled smart devices utilizing embedded processors, sensors, and wireless communication hardware have created an optimal ecosystem for the Internet of Things (IoT). IEEE802.15.4, IEEE802.11ah, WirelessHART, ZigBee Smart Energy, Bluetooth (BT), and Bluetooth Low Energy (BLE) are amongst the most commonly used wireless standards for IoT systems. Each of these standards has tradeoffs concerning power consumption, range of communication, network formation, security, reliability, and ease of implementation. The most widely used standards for IoT are Bluetooth, BLE, and Zigbee. This paper discusses the vulnerabilities in the implementation of the PHY and link layers of BLE. The link layer defines the scheme for establishing a link between two devices. Scanning devices are able to establish communication with other devices that are sending advertising packets. These advertising packets are sent out in a deterministic fashion. The advertising channels for BLE, specified by the PHY layer, are Channels 37, 38, and 39, at center frequencies 2.402, 2.426, and 2.480 GHz, respectively. This scheme for establishing a connection seems to introduce an unintentional gap in the security of the protocol. Creating and transmitting tones with center frequencies corresponding to those of the advertising channels, a victim BLE device will be unable to establish a connection with another BLE device. Jamming a mesh network of BLE devices relies on this same concept. The proposed jamming system is an inexpensive one which utilizes the following hardware. Three individual synthesizers, a microcontroller (MCU), Wilkinson power combiner, power amplifier, and antenna, integrated on a single PCB, are used to transmit a 3-tone signal. Due to the unprecedented nature of the COVID-19 pandemic, necessary adjustments were made to the jammer system design. In the first modified jamming scheme, a single synthesizer evaluation board, power amplifier, and antenna, are used to transmit jamming tones in the form of a frequency hop. Limitations of the frequency hop approach necessitated a second modified scheme. In this second scheme a synthesizer and two Software Defined Radios (SDR), connected to a personal computer, continuously generate three individual jamming tones. The proposed jammer and the modified ones all classify as constant jammers as the transmission of jamming signals is continuous. Both modified jamming schemes are tested. The results of jamming using the second modified scheme validate the objective of simultaneous jamming of the advertising channels of BLE devices. The success of the modified scheme enables the original goal of creating a relatively inexpensive custom PCB for BLE advertising channel jamming. By exploiting the weakness of the BLE protocol, the hope is to have the governing body for Bluetooth, Bluetooth Special Interest Group (SIG), improve security for the future releases of BLE

Effect of ethnicity and sex on vascular responses to environmental stressors: do prostaglandins contribute?

The effect of ethnicity and sex on the cardiovascular responses to environmental stressors and contribution of prostaglandins (PGs) to these responses were investigated in young White European (WE), Black African (BA) and South Asian (SA) men and women. Mental stress elicited responses consistent with the pattern of the alerting response in WEs, BA and SA men including endothelium-dependent forearm vasodilatation, but BA and SA women showed forearm vasoconstriction and BA women showed exaggerated pressor responses. Repetition of mental stress did not induce short, or medium term habituation of alerting responses in any group, but BA women showed sensitization of pressor responses and forearm vasoconstriction indicating vulnerability to mental stress-induced hypertension. On the other hand, BA and SA men, but not women show blunted endothelium-dependent dilatation relative to WEs during reactive hyperaemia and exercise hyperaemia. Vasodilator and vasoconstrictor PGs contributed to the vascular components of the alerting response in BAs and SAs, but not WEs. Further, PGs contributed to reactive hyperaemia and exercise hyperaemia in WE men and women, but in BAs and SAs, PGs played a minimal role in women. `We propose that this endothelial dysfunction makes BA and SA women especially vulnerable to cardiovascular disease caused by mental stress

A Small-Scale Field Trial of Pyriproxyfen-Impregnated Bed Nets against Pyrethroid-Resistant Anopheles gambiae s.s. in Western Kenya

Pyrethroid resistance is becoming a major problem for vector control programs, because at present, there are few suitable chemical substitutes for pyrethroids, as when used on bed nets the insecticide must have low mammalian toxicity as well as high activity to mosquitoes. Pyriproxyfen (PPF) is one of the most active chemicals among the juvenile hormone mimic (JHM) group. Sterilizing mosquitoes by using PPF could be a potential control measure for pyrethroid-resistant malaria vectors. We investigated the sterilizing effects of two types of PPF-impregnated bed nets - a 1% PPF-impregnated net and a 1% PPF +2% permethrin-impregnated net (Olyset Duo) - to pyrethroid-resistant wild population of Anopheles gambiae s.s. in western Kenya. High mortality of blood-fed mosquitos was observed 3 days post-collection, in the houses where PPF-impregnated nets were used, indicating the effect of PPF on the longevity of mosquitos that came in contact with the net. Reduction in the number of ovipositing females, number of eggs, and number of progeny per female were also observed in the houses in which both Olyset Duo and PPF-impregnated nets were used. This is the first field study showing the high sterilizing efficacy of PPF against wild pyrethroid-resistant An. gambiae s.s. population. In addition, we recognized the necessity of combined use of permethrin with PPF, in order to reduce the risk of mosquito bites and provide a level of personal protection. Further studies on wild pyrethroid-resistant mosquito populations such as An. arabiensis and An. funestus s.s. would provide more information on the practical use of the PPF-impregnated bed nets

Original article - ENHANCEMENT OF CUTANEOUS WOUND HEALING BY METHANOLIC EXTRACTS OF AGERATUM CONYZOIDES IN THE WISTAR RAT.

In a bid to test the wound healing effect of a crude methanolic extract of Ageratum conyzoides (Linn.), 20 animals were divided into two groups of ten animals each representing control and experimental groups. Each animal had a 2cm x 2cm area of skin on the right dorsolateral flank area marked and excised. The resulting area of skin wound in the experimental group was dressed with crude methanolic extract of Ageratum conyzoides at a five daily interval while the animals in the control group were dressed with normal saline at the same interval. The wound area was measured at the tenth post-operative day for animals in both groups and the percentage wound contraction calculated. Sample of granulation tissues and end scar obtained from these animals and prepared by routine paraffin wax method. Fibroblast and blood vessel counts were determined in both groups. The result showed a significant increase in the percentage wound contraction at day 10 in the experimental group compared with the control (82.3 ± 1.6 % vs 55.0 ± 4.2 %), P < 0.05. The wound of animals in both groups showed excellent granulation tissue formation and minimal signs of wound infection. There was a significant reduction in the mean fibroblast count in the experimental group compared with the control (44.2 ± 5.8/ high power field vs 90.2 ± 17. 4 / high power field),P < 0.05. The exact significance of this cannot however be determined. There was no significance difference in the vessel count. It was concluded that extract of Ageratum conyzoides has a better wound healing enhancing action compared with normal saline treated controls. This effect may be due to the antimicrobial properties of Ageratum conyzoides

Sterilising effects of pyriproxyfen on Anopheles arabiensis and its potential use in malaria control.

BACKGROUND: Insecticide resistance poses a major threat to current vector control campaigns. Insecticides with novel modes of action are therefore in high demand. Pyriproxyfen (PPF), a conventional mosquito pupacide, has a unique mode of action that also sterilises adult mosquitoes (unable to produce viable offspring) upon direct contact. However, the timing of PPF exposure in relation to when mosquitoes take a blood meal has an important impact on that sterilisation. This study investigated the relationship between different blood feeding and PPF exposure timings to determine the potential of PPF sterilisation in controlling Anopheles arabiensis. METHODS: Four treatment regimens were investigated: blood fed three days before PPF exposure (A), blood fed one day before PPF exposure (B), blood fed one day after PPF exposure (C) and blood fed three days after PPF exposure (D) for their impact on egg laying (fecundity) and the production of viable offspring (fertility), while the impact of PPF exposure on mosquito survival was investigated in the absence of a blood meal. All regimens and the survival study exposed mosquitoes to PPF via the bottle assay at 3 mg AI/m(2) for 30 minutes. RESULTS: Female mosquitoes that blood-fed one day prior to PPF exposure (regimen B), produced no viable offspring during that gonotrophic cycle (100% reduction in fertility). All other treatments had no significant effect. The observed reductions in fecundity and fertility were caused by the retention of eggs (97% of eggs retained, i.e. produced in the ovaries but not laid, in regimen B, p = 0.0004). Some of these retained eggs were deformed in shape. PPF exposure on mosquito survival in the absence of a blood meal was found to have no effect. CONCLUSIONS: The results presented here suggest that sterilising adult malaria vectors using PPF could form part of a malaria control strategy, taking advantage of the lack of reported resistance to PPF in mosquitoes and its unique mode of action. We propose that targeting resting mosquitoes, which are highly susceptible to PPF at low doses, is the optimal direction for developing this control tool