Address resolution protocol optimization

This paper proposes an improved Address Resolution Protocol (ARP) for Ethernet-based networks. In the proposed alternative method, the ARP request packets are not broadcasted but instead unicasted to an ARP server which will have all the mappings of all the hosts connected to the network. This significantly reduces ARP signaling and processing overhead. The ARP server obtains the mappings through a novel passive method that does not introduce additional overhead in the network. Furthermore, the use of the ARP server makes it much easier to secure the network against certain attacks like ARP poisoning

Efficient unified Montgomery inversion with multibit shifting

Computation of multiplicative inverses in finite fields GF(p) and GF(2/sup n/) is the most time-consuming operation in elliptic curve cryptography, especially when affine co-ordinates are used. Since the existing algorithms based on the extended Euclidean algorithm do not permit a fast software implementation, projective co-ordinates, which eliminate almost all of the inversion operations from the curve arithmetic, are preferred. In the paper, the authors demonstrate that affine co-ordinate implementation provides a comparable speed to that of projective co-ordinates with careful hardware realisation of existing algorithms for calculating inverses in both fields without utilising special moduli or irreducible polynomials. They present two inversion algorithms for binary extension and prime fields, which are slightly modified versions of the Montgomery inversion algorithm. The similarity of the two algorithms allows the design of a single unified hardware architecture that performs the computation of inversion in both fields. They also propose a hardware structure where the field elements are represented using a multi-word format. This feature allows a scalable architecture able to operate in a broad range of precision, which has certain advantages in cryptographic applications. In addition, they include statistical comparison of four inversion algorithms in order to help choose the best one amongst them for implementation onto hardware

Multiple KH Domains of Poly C Binding Protein are Required for its Trans-Activation on the Proximal Promoter of the Mu-Opioid Receptor Gene

The mu-opioid receptor (MOR) has been shown to mediate morphine induced analgesia, addiction, and tolerance. The expression of the major product of the MOR (MOR-1) gene has been found to be driven by two promoters, a distal promoter and a proximal promoter. The proximal promoter region has been shown in previous studies to be the major promoter for the regulation of MOR gene transcription in the adult mouse brain and embryonic development. Recent studies have shown that single-stranded DNA binding proteins (such as Poly C Binding Protein) are involved in transcriptional regulation of mouse MOR gene. Poly C binding protein (PCBPs) is categorized in the family of hnRNP\u27s, containing multiple K-Homology (KH) domains, which is involved in RNA stabilization, translational activation, and gene silencing. In this study, we attempted to determine the trans-activation domains of PCBP and examine the regulatory effects of each trans-activation domain of PCBP in MOR transcription. Mouse neuronal cells (N2A) were transiently transfected with various truncation constructs of PCBP to determine which domains were important in trans­ activation. Our preliminary data suggests that at least two KH domains were required for PCBP to display its trans-activation activity

Design of multi-homing architecture for mobile hosts

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.This thesis proposes a new multi-homing mobile architecture for future heterogeneous network environment. First, a new multi-homed mobile architecture called Multi Network Switching enabled Mobile IPv6 (MNS-MIP6) is proposed which enables a Mobile Node (MN) having multiple communication paths between itself and its Correspondent Node (CN) to take full advantage of being multi-homed. Multiple communication paths exist because MN, CN, or both are simultaneously attached to multiple access networks. A new sub layer is introduced within IP layer of the host’s protocol stack. A context is established between the MN and the CN. Through this context, additional IP addresses are exchanged between the two. Our MNS-MIP6 architecture allows one communication to smoothly switch from one interface/communication path to another. This switch remains transparent to other layers above IP. Second, to make communication more reliable in multi-homed mobile environments, a new failure detection and recovery mechanism called Mobile Reach ability Protocol (M-REAP) is designed within the proposed MNS-MIP6 architecture. The analysis shows that our new mechanism makes communication more reliable than the existing failure detection and recovery procedures in multi-homed mobile environments. Third, a new network selection mechanism is introduced in the proposed architecture which enables a multi-homed MN to choose the network best suited for particular application traffic. A Policy Engine is defined which takes parameters from iv the available networks, compares them according to application profiles and user preferences, and chooses the best network. The results show that in multi-homed mobile environment, load can be shared among different networks/interfaces through our proposed load sharing mechanism. Fourth, a seamless handover procedure is introduced in the system which enables multi-homed MN to seamlessly roam in a heterogeneous network environment. Layer 2 triggers are defined which assist in handover process. When Signal to Noise Ratio (SNR) on a currently used active interface becomes low, a switch is made to a different active interface. We show through mathematical and simulation analysis that our proposed scheme outperforms the existing popular handover management enhancement scheme in MIPv6 networks namely Fast Handover for MIPv6 (FMIPv6). Finally, a mechanism is introduced to allow legacy hosts to communicate with MNS-MIP6 MNs and gain the benefits of reliability, load sharing and seamless handover. The mechanism involves introducing middle boxes in CN’s network. These boxes are called Proxy-MNS boxes. Context is established between the middle boxes and a multi-homed MN

Multiple KH Domains of Poly C Binding Protein are Required for its Trans-Activation on the Proximal Promoter of the Mu-Opioid Receptor Gene

The mu-opioid receptor (MOR) has been shown to mediate morphine induced analgesia, addiction, and tolerance. The expression of the major product of the MOR (MOR-1) gene has been found to be driven by two promoters, a distal promoter and a proximal promoter. The proximal promoter region has been shown in previous studies to be the major promoter for the regulation of MOR gene transcription in the adult mouse brain and embryonic development. Recent studies have shown that single-stranded DNA binding proteins (such as Poly C Binding Protein) are involved in transcriptional regulation of mouse MOR gene. Poly C binding protein (PCBPs) is categorized in the family of hnRNP\u27s, containing multiple K-Homology (KH) domains, which is involved in RNA stabilization, translational activation, and gene silencing. In this study, we attempted to determine the trans-activation domains of PCBP and examine the regulatory effects of each trans-activation domain of PCBP in MOR transcription. Mouse neuronal cells (N2A) were transiently transfected with various truncation constructs of PCBP to determine which domains were important in trans­ activation. Our preliminary data suggests that at least two KH domains were required for PCBP to display its trans-activation activity

Effect of Increasing Stocking Density on Performance and Heterophil/Lymphocyte Ratios in Broilers

An experiment on space allowance of 0.095, 0.071, 0.057 and 0.048 m2/bird on wire mesh cages was conducted to study their effects on live-weight, feed intake and feed conversion of Orgal broilers from the age of 4 to 10 weeks. Heterophil/lymphocyte (H/L) ratio,an indicator of stress was also studied to determine whether over-crowding would effect this ratio. During the first 2 weeks of the experiment increasing stocking is reduced feed intake and improve feed conversion without significantly affecting growth rate. Overall, birds on the most liberal floor space allowance (0.095 m2/bird) had the best growth rate (39.2 glda») but this was achieved at a significantly higher feed intake (127.9 g/day) and poorer feed conversion (3.3).Conversely, birds on the highest stocking density (0.048 ,rz2lbiTd) had the poorest performance in terms of growlh rate (32.2 g/day) and feed intake(90.6 g/day). Birds on the two higher stocking density were constantly under stress as indicated by their relatively high H/L. ratios from the fourth week, of the study onwards, these two treatments also had higher mortalities. The results of the present study showed that stress associated with overcrowding reduced performance in broilers. A space allowance of 0.071 m2/bird is sufficient under om- local conditions for broiled reared in raised floor cages

Chiral and Parity Symmetry Breaking for Planar Fermions: Effects of a Heat Bath and Uniform External Magnetic Field

We study chiral symmetry breaking for relativistic fermions, described by a parity violating Lagrangian in 2+1-dimensions, in the presence of a heat bath and a uniform external magnetic field. Working within their four-component formalism allows for the inclusion of both parity-even and -odd mass terms. Therefore, we can define two types of fermion anti-fermion condensates. For a given value of the magnetic field, there exist two different critical temperatures which would render one of these condensates identically zero, while the other would survive. Our analysis is completely general: it requires no particular simplifying hierarchy among the energy scales involved, namely, bare masses, field strength and temperature. However, we do reproduce some earlier results, obtained or anticipated in literature, corresponding to special kinematical regimes for the parity conserving case. Relating the chiral condensate to the one-loop effective Lagrangian, we also obtain the magnetization and the pair production rate for different fermion species in a uniform electric field through the replacement $B\to-iE$.Comment: 9 pages, 10 figure

Light emission, light detection and strain sensing with nanocrystalline graphene

Graphene is of increasing interest for optoelectronic applications exploiting light detection, light emission and light modulation. Intrinsically light matter interaction in graphene is of a broadband type. However by integrating graphene into optical micro cavities also narrow band light emitters and detectors have been demonstrated. The devices benefit from the transparency, conductivity and processability of the atomically thin material. To this end we explore in this work the feasibility of replacing graphene by nanocrystalline graphene, a material which can be grown on dielectric surfaces without catalyst by graphitization of polymeric films. We have studied the formation of nanocrystalline graphene on various substrates and under different graphitization conditions. The samples were characterized by resistance, optical transmission, Raman, X-ray photoelectron spectroscopy, atomic force microscopy and electron microscopy measurements. The conducting and transparent wafer-scale material with nanometer grain size was also patterned and integrated into devices for studying light-matter interaction. The measurements show that nanocrystalline graphene can be exploited as an incandescent emitter and bolometric detector similar to crystalline graphene. Moreover the material exhibits piezoresistive behavior which makes nanocrystalline graphene interesting for transparent strain sensors