Exchange Phase Research Articles

Identification of a peptide derived from a Bothrops moojeni metalloprotease with in vitro inhibitory action on the Plasmodium falciparum purine nucleoside phosphorylase enzyme (PfPNP)

There is a growing need for research on new antimalarial agents against Plasmodium falciparum infection, especially in regards to planning molecular architecture for specific molecular targets of the parasite. Thus, a metalloprotease from Bothrops moojeni, known as BmooMPα-I, was explored in this study, through in silico assays, aiming at the development of a peptide generated from this molecule with potential inhibitory action on PfPNP, an enzyme necessary for the survival of the parasite. In order to isolate BmooMPα-I, cation exchange and reverse phase chromatographies were performed, followed by in vitro assays of antiparasitic activity against the W2 strain of P. falciparum. The interactions between BmooMPα-I and PfPNP were evaluated via docking, and the resulting peptide, described as Pep1 BM, was selected according to the BmooMPα-I region demonstrating the best interaction score with the target of interest. The values for the specific activities of the PfPNP reaction were measured using the inorganic phosphate substrate and MESG. The fraction corresponding to BmooMPα-I was identified as fraction 4 in the cation exchange chromatography step, due to proteolytic activity on casein and the presence of a major band at ≅ 23 kDa. BmooMPα-I was able to inhibit in vitro growth of W2 P. falciparum, with an IC50 value of 16.14 μg/mL. Virtual screening with Pep1 BM demonstrated two PfPNP target binding regions, with ΔG values at the interaction interface of −10.75 kcal/mol and −11.74 kcal/mol. A significant reduction in the enzymatic activity of PfPNP was observed in the presence of Pep 1 BM when compared to the assay in the absence of this possible inhibitor. BmooMPα-I showed activity in vitro against W2 P. falciparum. By means of in silico techniques, the Pep 1 BM was identified as having potential binding affinity to the catalytic site of PfPNP and of inhibiting its catalytic activity in vitro.

Spin-flip scattering engendered quantum spin torque in a Josephson junction.

We examine a Josephson junction with two ferromagnets and a magnetic impurity sandwiched between two superconductors. In such ferromagnetic Josephson junctions, equilibrium spin torque exists only when ferromagnets are misaligned. This is explained via the 'conventional' mechanism of spin transfer torque, which owes its origin to the misalignment of two ferromagnets. However, we see surprisingly when the magnetic moments of the ferromagnets are aligned parallel or anti-parallel, there is a finite equilibrium spin torque due to the quantum mechanism of spin-flip scattering. We explore the properties of this unique spin-flip scattering-induced equilibrium quantum spin torque, especially its tunability via exchange coupling and phase difference across the superconductors.

VU limit pre‐assessment for high‐speed railway considering a grid connection scheme

Single-phase 25 kV AC traction power supply systems (TPSSs) are widely used in high-speed railways, leading to an increasingly prominent problem of voltage unbalance (VU) in the power grid. To fairly regulate the system VU level, implementing VU limit pre-assessment is an urgent need. A grid connection scheme including traction transformer selection and exchange phase connection design is a vital part of TPSS design that obviously affects the VU factor of power systems. A uniform mathematical model is established using Thevenin's theorem, which reveals the impact of multiple grid connection schemes on the VU propagation behaviour of a three-phase grid. Afterwards, under the requirements of IEC/TR 61000-3-13, an improved VU limit pre-assessment process is proposed, which correlates mapping between the grid connection scheme and VU limit. The unbalance compensation calculation is given, adopting the allocation limit; furthermore, the optimal design of the grid connection scheme with minimised compensation capacity as an object is presented. The correctness of the model and the rationality of the pre-assessment process are verified by a case study.

Anonymity preserving and round effective three-party authentication key exchange protocol based on chaotic maps.

Three-party authentication key exchange (3PAKE) is a protocol that allows two users to set up a common session key with the help of a trusted remote server, which is effective for secret communication between clients in a large-scale network environment. Since chaotic maps have superior characteristics, researchers have recently presented some of the studies that apply it to authentication key exchange and cryptography. Providing user anonymity in the authentication key exchange is one of the important security requirements to protect users' personal secrets. We analyse Lu et al.'s scheme which attempts to provide user anonymity and we prove that his scheme has errors in the key exchange phase and password change phase. We propose a round-effective three-party authentication key exchange (3PAKE) protocol that provides user anonymity and we analyse its security properties based on BAN logic and AVISPA tool.

SSPSoC: A Secure SDN-Based Protocol over MPSoC

In recent years, Multi-Processor System-on-Chips (MPSoCs) are widely deployed in safety-critical embedded systems. The Cloud-of-Chips (CoC) is a scalable MPSoC architecture comprised of a large number of interconnected Integrated Circuits (IC) and Processing Clusters (PC) destined for critical systems. While many researches have focused on addressing the hardware issues of MPSoCs, the communication over them has not been very well explored. Following the SDN concept, we propose a new protocol in order to secure the communication and efficiently manage the routing within the CoC. The SSPSoC includes a private key derivation phase, a group key agreement (GKA) phase, and a data exchange phase in order to ensure that basic security primitives are preserved and provide secure communication. Furthermore, a network of 1-30 nodes is set in order to validate the proposed protocol and measure the network performance and memory consumption of the proposed protocol.

Acoustic oscillations driven by boundary mass exchange

Thermoacoustic instability – self-sustained pressure oscillations triggered by temperature gradients – has become an increasingly studied topic in the context of energy conversion. Generally, the process relies on conductive heat transfer between a solid and the fluid in which the generated pressure oscillations are sustained. In the present study, the thermoacoustic theory is extended to include mass transfer; specifically, the working fluid is modified so as to incorporate a ‘reactive’ gas, able to exchange phase with a solid/liquid boundary through a sorption process (or through evaporation/condensation), such that most heat is transferred in the form of latent heat rather than through conduction. A set of differential equations is derived, accounting for phase-exchange heat and mass transfer, and de-coupled via a small-amplitude asymptotic expansion. These equations are solved and subsequently manipulated into the form of a wave equation, representing the small perturbation on the pressure field, and used to derive expressions for the time-averaged, second-order heat and mass fluxes. A stability analysis is performed on the wave equation, from which the marginal stability curve is calculated in terms of the temperature difference, $\unicode[STIX]{x0394}T_{onset}$, required for initiation of self-sustained oscillations. Calculated stability curves are compared with published experimental results, showing good agreement. Effects of gas mixture composition are studied, indicating that a lower heat capacity of the inert component, combined with a low boiling temperature and high latent heat of the reactive component substantially lower $\unicode[STIX]{x0394}T_{onset}$. Furthermore, an increase in the average mole fraction of the reactive gas, $C_{m}$ strongly affects onset conditions, leading to $\unicode[STIX]{x0394}T_{onset}\sim 5\,^{\circ }\text{C}$ at the highest value of $C_{m}$ achievable under atmospheric pressure. An analysis of the system limit cycle is performed for a wide range of parameters, indicating a systematic decrease in the temperature difference capable of sustaining the limit cycle, as well as a significant distortion of the acoustic wave form as the phase-exchange mechanism becomes dominant. These findings, combined, reveal the underlying mechanisms by which a phase-exchange engine may produce more acoustic power than its counterpart ‘classical’ thermoacoustic system, while its temperature difference is substantially lower.

Improvement of the Spatial Channel Matrix Mapping and Precoding Algorithm in the Forest Environment

Few studies have been conducted on the forest spatial channel matrix, most of which were conducted by experts and scholars in the field of communications. The mature cellular network channel coding matrix was “transplanted” to the vegetation-covered space, and the effects of the various vegetation dielectric constants, the forest canopy density and other objective factors on the traditional cellular channel were ignored. To overcome this problem, this paper built a relay network that is suitable for forest environments. This network was an effective complement to the existing cellular communication network for expanding the coverage of signals in the forest. On this basis, this paper analysed the multi-antenna relay transmission protocol and proposed an additional spatial channel matching (mapping) matrix between the forward and backward filters. This matrix was designed to consider the effect of the complex forest environment on the channel to reduce the relaying noise power. Then, under the forest cellular relay network topology, a spatial channel matrix structure (based on unitary matrix) that is suitable for the forest environment is proposed. This matrix can be incorporated into various relay protocols and considers the source node preprocessing operation and the destination node equalizer. The forest relay cooperative network that is proposed in this paper can effectively expand the coverage of signals in forest areas; however, due to the inherent limitations of the relay network, many problems will be encountered in practical applications. For example, the precoding scheme that is based on phase correction requires the terminal node to feed the phase correction factor back to the forest base station node; however, the system performance is substantially affected by the feedback accuracy and the arrival delay difference. Due to the uncertain rank of the integrated channel in the forest base station precoding scheme, it was necessary to adapt to a variety of antenna ports, which rendered the design of the precoding codebook highly difficult. In addition, when the number of transmission layers was greater than 1, the local precoding scheme also encountered the problem of inter-layer interference (ILI). Based on a detailed analysis of the shortcomings of the previous scheme and the strategy of partial coherence transmission, this paper proposes an improved algorithm of incoherent joint transmission technology and an improved precoding scheme that are suitable for forest relay systems. The signal that is transmitted by the relay node and the feedback signal is corrected via layer exchange between cells and via phase correction. By changing the layer’s exchange information and phase information, it can be adapted to various forest environments, such as artificial forests, natural forests, and virgin forests. Finally, the outage probability is considered as a performance indicator in the simulation of the forest environment wireless relay system. The theoretical analysis and simulation results demonstrate the satisfactory performance of the proposed spatial channel mapping matrix and the forest relay precoding scheme.

A New Secure Passwordless Multi-Server Modified Authenticated Master-Key Agreement Scheme Based on Hardware-Software and Iriscode Identifiers Through SSL/TLS Protocol for E-learning and Similar Web-based Services

There is a growing concern about systems security and how to organize it. This is because the internet which is the backbone of all systems is regarded as unsafe. Also, the internet transmits all connection transactions in the E-learning and similar web-based systems and as a result, intruders and attackers by abusing security holes can compromise the system. The E-learning and other similar systems should be safe against threats and manipulation by intruders and should protect the privacy of users. The purpose of this paper is to provide an authentication model based on hardware, software and iriscode identifiers through the SSL/TLS protocol, in order to significantly improve the security and privacy level, while at the same time, maintain the system performance at an acceptable level. There are major differences between our model and other similar works, such as: no need to password in registration and login phase, using of iriscode identifier, isolation of users profiles based on hardware and software identifiers of relying party, enhancing master secret key exchange phase in the SSL/TLS protocol, no need to password change phase, strong performance in comparison with other approaches because of using SHA-3 function and removing password change phase, capability of providing authentication services over large networks and internet. Also according to conducted studies and tests, the mentioned solution can significantly improve the system security, as well as maintain its function at an acceptable level. Therefore the proposed model easily can be used for immunize E-learning and similar web-based systems that works through internet. The proposed model improves the 32.50% security and 63.58% execution time in comparison to average of five newest methods.

Purification and Characterization of Plantaricin LPL-1, a Novel Class IIa Bacteriocin Produced by Lactobacillus plantarum LPL-1 Isolated From Fermented Fish.

Bacteriocins are ribosomally synthesized peptides or proteins possessing antibacterial activity against foodborne pathogens and spoilage bacteria. A novel bacteriocin, plantaricin LPL-1 was determined as a class IIa bacteriocin according to the YGNGV motif, and producer strain Lactobacillus plantarum LPL-1 was identified based on physio-biochemical characteristics and 16S rDNA sequence. The novel bacteriocin, plantaricin LPL-1 was purified by salt precipitation, cation exchange, gel filtration, and reverse phase high-performance liquid chromatography (RP-HPLC). The molecular mass of plantaricin LPL-1 was 4347.8467 Da by Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) analysis and entire amino acid sequence of plantaricin LPL-1 was VIADKYYGNGVSCGKHTCTVDWGEAFSCSVSHLANFGHGKC. Plantaricin LPL-1 possessed the merits of easy degradation by proteases, wide pH stability (2–10), high thermal stability (121°C, 20 min), surfactants stability and bactericidal activity against foodborne spoilage and pathogens bacteria. The mode action and membrane permeabilization of plantaricin was identified. The information of plantaricin LPL-1 indicated that it is not only a novel class IIa bacteriocin, but also a promising natural and safe biologic preservative for the food preservation industry.

Development, validation and application to real samples of a liquid chromatography with tandem mass spectrometry method for the determination of tetracyclines in beeswax

Beeswax is a valuable honeybee product, which finds applications in the food and pharmaceutical industries, as well as in cosmetic production. However, some substances used in apiculture, like tetracyclines, can be delivered to hives where they cause contamination of honeybee products such as beeswax. Tetracyclines are commonly used for the treatment of American and European foulbrood diseases, but in the European Union their usage by beekeepers is forbidden. Thus, a sensitive method for the analysis of tetracyclines in beeswax is an important analytical tool. A new liquid chromatography with tandem mass spectrometry method for the analysis of tetracyclines including oxytetracycline, 4-epioxytetracycline, tetracycline, 4-epitetracycline, chlorotetracycline, 4-epichlorotetracycline, and doxycycline in beeswax was developed. The method involved dilution of beeswax in n-hexane after a melting step, liquid-liquid extraction with oxalic acid and clean-up using a weak cation exchange phase. Satisfactory separation was performed on an octadecyl column with 0.1% formic acid and acetonitrile in a total run time of 5min. The application of this method was evaluated by the analysis of real beeswax samples. The presence of oxytetracycline was confirmed in 5 out of 48 tested beeswax samples, which shows the method can be successfully used to determine the tetracyclines in beeswax.

Privacy-oriented dependency via deniable SIGMA protocol

The IoT era has led to a complex interplay between the communication security and the storage service providers. The secure key exchange is crucial from the perspective of communication confidentiality. Similarly, the evidence-based cryptography provides the crucial feature such as accountability with respect to both, the participating entities as well as the protocol instance. However, privacy concerned applications and user perspective regarding protocol instance execution require exactly opposite features, i.e., deniability. There is no denying about the relevance of this feature in the application that might incur a heavy payoff to a user, in case application went malicious. Therefore, the deniability feature provides a protection shield beyond the application execution as well as user participation. We propose a key exchange protocol that is based on SIGMA key exchange protocol and still provides assurance on deniability feature. In particular, this stronger notion of deniability (as featured in our protocol) is defined through a distinguisher algorithm provided with an entire set of public keys, secret keys, and the ephemeral Diffie–Hellman key of the denying party. Our proposition, based on ring signatures, provide the justification of the fact that any single party alone can produce simulated transcripts of the protocol (without any peer participation), thereby, supporting the deniability feature. Moreover, we strengthen the SIGMA resulting session keys by involving (in addition) long-term keys during the Diffie–Hellman key exchange phase of the protocol. Our proposition preserves the modular construction of the protocol and does not require an increased number of the protocol rounds as a compensation for added deniability features.

Improvement of a Splicing Machine to Decrease Abrupt Tension Changes and Tail Defects during the Roll Exchange Process in a Roll-to-Roll Manufacturing System

The use of the splicing system is necessary to exchange a fully unwound roll to a new one without stopping the roll-to-roll manufacturing machine. However, abrupt tension changes and tail defects, which is an overlap of completely unwound films with films in the process of being unwound, could occur during the roll exchange phase causing film loss and deterioration of product quality. Herein, we improved the splicing machine in an industrial scale R2R manufacturing system to decrease abrupt tension errors and tail defects. First, the effects of the factors generating the tail defects in the splicing machine on the net tail lengths were analyzed using designed mathematical models. Furthermore, the reason for the abrupt tension disturbance in the roll exchange process was determined. Based on the analyses, a passive dancer system was applied to the unwinding section to attenuate the tension error, and the time interval between the pressing and cutting phases was decreased by changing the signal processing method of the previous version of the splicing machine. Experimental results showed that the abrupt tension change was decreased by an average of 46.5%, while tail lengths were decreased by more than 2.5 times, thereby verifying the superior performance of the upgraded splicing machine.

Rapid charge variant analysis of monoclonal antibodies to support lead candidate biopharmaceutical development

Biopharmaceuticals are complex therapeutic proteins produced in living cells that undergo a variety of enzymatic and non-enzymatic posttranslational modifications both intracellularly and also following secretion into the condition media. Characterization of these posttranslational modifications is a regulatory requirement to ensure that the molecule meets the required levels of quality to ensure patient safety. Ion exchange chromatography, particularly cation exchange, is routinely used for the determination of the charge variant profile of monoclonal antibodies (mAbs) using either an increasing concentration of salt or the generation of a pH gradient to facilitate elution of the mAb charge variants from the cation exchange phase. In this study, salt and pH gradient elution modes were compared to develop an optimized separation for the mAb standard reference material from NIST on a strong cation exchange phase. Separation using the pH gradient approach was found to outperform salt gradient separation. The developed pH gradient method was transformed into an ultra-fast separation method to facilitate rapid molecular profiling and triage during lead candidate and cell line development activities. The ultrafast method was validated and showed excellent performance for linearity and precision as well as applicability for the analysis of a variety of mAbs with different pI-values. The method has proven suitable for the integration into process analytical technology (PAT) frameworks and was found to be powerful in combination with automated data analysis strategies for obtaining low end-to-end processing time. This was demonstrated by the acquisition and analysis of in total 45 runs within only 5 h. The method was next applied for profiling in-house produced candidate biosimilars of trastuzumab and enabled the assessment of the charge variant profile of these candidates in <25 min. Differences identified for trastuzumab expressed using a stable CHO cell line were found to result from incomplete cleavage of the signal peptide from the light chain as determined using high resolution reversed-phase LC-MS following digestion with IdeS protease and disulphide bond reduction. The proposed method is well suited for molecular triage during cell line development or indeed for potential process analytical technology application during larger scale manufacture.

The Development of Arabic Learning Model by Using Multimedia of Computer at UIN STS Jambi

This research and development result in a learning model that could be used to improve oral communication that was divided into five different learning phase, which is, orientation phase, ordering command phase, role exchange phase, structured practice phase, and guided practice phase. It could also improve one’s understanding of arabic grammar/qawaid (nahwu wa sharfi) which consists of elements in Arabic language that consist of Letters (harf), Words (kalimatu), Sentences (jumlatu), sibhuljumlah and articles (uslub) and fit into Arabic grammar. The result of this study implies that development result study model emphasize in college students’ activities in their learning process. The learning process done by the lecturers using Arabic language as the language of instruction started by the pronunciation of the vocabularies and it’s demonstration without translating it into Bahasa Indonesia. After they were capable of demonstrating the acquired vocabularies, college students trained in reproducing the language orally using question and answer activities, whether structurally, or guided. The study results showed that the quality of this multimedia teaching of Arabic language fall into the ‘fine’ category, acquiring average score of 43.92 and ideal percentage of 87.85%.

Molecular switch-like regulation enables global subunit coordination in a viral ring ATPase

Subunits in multimeric ring-shaped motors must coordinate their activities to ensure correct and efficient performance of their mechanical tasks. Here, we study WT and arginine finger mutants of the pentameric bacteriophage φ29 DNA packaging motor. Our results reveal the molecular interactions necessary for the coordination of ADP-ATP exchange and ATP hydrolysis of the motor's biphasic mechanochemical cycle. We show that two distinct regulatory mechanisms determine this coordination. In the first mechanism, the DNA up-regulates a single subunit's catalytic activity, transforming it into a global regulator that initiates the nucleotide exchange phase and the hydrolysis phase. In the second, an arginine finger in each subunit promotes ADP-ATP exchange and ATP hydrolysis of its neighbor. Accordingly, we suggest that the subunits perform the roles described for GDP exchange factors and GTPase-activating proteins observed in small GTPases. We propose that these mechanisms are fundamental to intersubunit coordination and are likely present in other ring ATPases.

Modeling of fuel retention and hydrogen-isotope exchange removal from the pre-damaged tungsten material

The fuel retention and hydrogen-isotope exchange removal in the pre-damaged tungsten (W) have been investigated in the present work. The fuel retention code Hydrogen Isotope Inventory Processes Code (HIIPC) has been upgraded to model the isotope-exchange process. Three types of defects are taken into account in the pre-irradiated W, including the dislocation, mono-vacancy, vacancy cluster defects. The SRIM code is employed to calculate the radiation-damage defect distribution. Three phrases are modeled by controlling the source terms by using HIIPC code. (i) deuterium (D) retention phrase, pre-damaged W is irradiated by the D flux; (ii) waiting period, both of the D and hydrogen (H) fluxes are switched off; (iii) isotope exchange phase, the W material is irradiated by H atoms. It is found that enhancing implantation H fluence can reduce the retained D significantly. The simulation also confirms D retention increases with the irradiation damage (displacement per atoms, dpa), until saturation occur. De-trapping energy plays an important role on the D retention, especially for high material temperature. The modeling results are compared with the experiment measurement, showing the good agreement.

Real-time secure communication for Smart City in high-speed Big Data environment

The recent development in the technology brings the concept of Smart City that is achieved through real-time city related intelligent decisions by analyzing the data harvested from various smart systems in the city using millions of sensors and devices connected over the Internet, termed as Internet of Things (IoT). These devices generate the overwhelming volume of high-speed streaming data, termed as Big Data. However, the generation of city data at a remote location and then transmitting it to central city servers for analysis purpose raises the concerns of security and privacy. On the other hand, providing security to such Big Data streaming requires a high-speed security system that can work in a real-time environment without providing any delay that may slow down the overall performance of the Smart City System. To overthrown these challenges, in this paper, we proposed an efficient and real-time Smart City security system by providing strong intrusion detection at intelligent city building (ICB) and also a security protocol to protect the communication between the remote smart system(RSS)/User and the city analysis building, i.e., ICB. The proposed communication security protocol consists of various phases, i.e., registration phase, session key exchange phase, session key revocation phase, and data transmission phases from RSS to ICB as well as from User to ICB. Vast security analyses are performed to evaluate the credibility of the system. The proposed system is also evaluated on efficiency in terms of computation cost and throughput of overall functions used in the system. The system’s evaluation and the comparative study with existing system show that the prosed system is secure, more efficient, and able to work in a real-time, high-speed Smart City environment.

Fabrication of nanoarchitectured TiO2(B)@C/rGO electrode for 4 V quasi-solid-state nanohybrid supercapacitors

Novel TiO2(B)@C/rGO nanoarchitectures are fabricated by combining hydrothermal treatment, ions exchange, and topological phase transformation as well as carbon modification. Asymmetric hybrid Li-ion nanohybrids supercapacitors with high energy and power densities are constructed by combining hybridized anode, which can supply both pseudo capacitance from TiO2(B) and electrochemical double layer capacitance (EDLC) from nanocarbons (graphene nanosheets and amorphous carbon layer), and activated carbon (AC) as EDLC type cathode. The high power density is realized readily via both the modification of nanocarbons, which not only improve the electric conductivity but introduce extra Faradic capacitance, and the employment of high-voltage formulated ionic liquids electrolyte as well as ionogel polymer separator. Such a balanceable and complementary design between electrode and electrolyte allow rapid ion and electron transport in ionic liquid-based electrolyte and hybridized electrodes. The maximum energy and power density of 59.4 W h/kg and 17.3 kW/kg can be readily realized at 40 °C on account of the special characteristic of ionic liquids. These results clearly demonstrate that high performance nanohybrid supercapacitors can be actualized through the subtle combination of nanohybridized electrodes and high voltage formulated ionic-liquid/lithium-salt electrolytes, which make them promising power-type energy storage devices for hybrid electric vehicles.

Obtention and characterization of the recombinant simian Interleukin-15 in Escherichia coli for the preclinical assessment of an IL-15-based therapeutic vaccine

ABSTRACTRecombinant simian IL-15 (siIL-15) was obtained for the preclinical assessment of an anti-human IL-15 vaccine. For this purpose, the cDNA from peripheral blood mononuclear cells of a Macaca fascicularis monkey was cloned into a pIL-2 vector. The siIL-15 was expressed in Escherichia coli strain W3110 as an insoluble protein which accounted for 13% of the total cellular proteins. Inclusion bodies were solubilized in an 8 M urea solution, which was purified by ion exchange and reverse phase chromatography up to 92% purity. The protein identity was validated by electrospray ionization-mass spectrometry, confirming the presence of the amino acids which distinguish the siIL-15 from human IL-15. The purified siIL-15 stimulates the proliferation of cytotoxic T-lymphocytes line (CTLL)-2 and Kit 225 cells with EC50 values of 3.1 and 32.5 ng/mL, respectively. Antisera from modified human IL-15-immunized macaques were reactive to human and simian IL-15 in enzyme-linked immunosorbent assays. Moreover, the anti-human IL-15 antibodies from immune sera inhibited siIL-15 activity in CTLL-2 and Kit 225 cells, supporting the activity and purity of recombinant siIL-15. These results indicate that the recombinant siIL-15 is biologically active in two IL-15-dependent cell lines, and it is also suitable for the preclinical evaluation of an IL-15-based therapeutic vaccine.

Spatial Signature Modulation: A Novel Secure Modulation Approach for MIMO Wiretap Channel

Security in physical and application layers have been always thought of as a complementary paradigm. In this paper, we argue that potential cooperation between physical and application layers provides several advantages and unique features that are not available in each paradigm by itself. The problem of exchanging confidential messages between nodes, A and B, in the presenceof an active adversary, E, over an insecure MIMO channel is considered. We introduce a double layer spatial signature modulation (SSM) in which the transmitted information is conveyed into the spatial signature of the transmitting antenna array observed by the intended receiver. Meanwhile, any other eavesdropper does not share the same bearing angle of the legitimate receiver obtains infinitesimally small amount of information. Further, to establish a secure link, A and B are required to share a secret common information prior to communication while keeping E ignorant about it. To that end, we introduce a novel physical layer assisted secret key agreement (SKA) protocol that leverages the cooperation between physical and application layer security. Angle of Arrival (AoA) and Angle of Departure (AoD) are physical layer parameters that can be exploited not only for their well performance at low SNR, but also for their contextual meaning that provides security advantages. In the proposed SKA protocol, AoA is explored as a physical mean for message source authentication, meanwhile, AoD is used as a common source of randomness in a smart signal processing approach to generate secret key bits without any extra communication overhead. We show that E can be kept ignorant about the generated key bit stream conditioned on its physical location. This work introduces the notion of physical hardness to an adversary pursuing either active or passive strategy. After establishing a secret common information, we show that the continuous use of AoA as a mean for message source authenticity provides a considerable advantage against active adversary during the message exchange phase. Extending the proposed scheme to a mobile communication environment is also provided. Finally, quantitative analysis for the security gain due to the potential cooperation between physical and application layer security is developed..