Signature Code Research Articles

Digital Image Protection using Keyed Hash Function

Digital image authentication is an essential attribute for protecting digital image from piracy and copyright violator. Anti-piracy, digital watermarking, and ownership verification are some mechanisms evolving over the years for achieving digital image authentication. Cryptographic primitives, such as hash function, digital signature, and message authentication codes are being used in several applications including digital image authentication. Use of Least Significant Bit (LSB) is one of the classical approaches for digital image authentication. Although LSB approach is efficient, it does not provide adequate security services. On the other hand, digital signature-based image authentication provides better security, but with added computational cost in comparison with LSB approach. Furthermore, digital signature-based authentication approach requires managing public key infrastructure. Considering security weakness of LSB-based approach and cost overhead of public key based approach, the authors present a digital image authentication scheme using LSB and message authentication codes (MAC). The MAC-based approach for authenticating digital image is secure and efficient approach without public key management overhead. The authors also provide experimental results of the proposed scheme using MATLAB. The experimental results show that the proposed scheme is efficient and secure in comparisons with other schemes.

Abstract A23: A non-coding RNA panel predicts intermediate-risk childhood rhabdomyosarcoma prognosis better than standard pathologic criteria and coding genes

Abstract Introduction: Rhabdomyosarcoma (RMS) is the most common pediatric soft-tissue sarcoma, stratified by the Children's Oncology Group (COG) into low/intermediate/high risk based on clinical outcomes. However, most patients are categorized as intermediate-risk where survival is highly heterogeneous, thus suggesting an inability to accurately stratify a majority of patients. We profiled intermediate-risk RMS's for levels of coding and non-coding transcripts to construct prognostic signatures. The goal was to identify panels of RNAs that reflect underlying tumor biology and provide better risk stratification than routine clinicopathologic parameters. Methods: Transcriptomes from 79 prospectively-obtained primary tumors from intermediate-risk RMS patients under COG clinical trial protocols were profiled on Affymetrix Human Exon 1.0 ST microarrays. Expressions of 1,400,033 probe sets representing annotated and unannotated transcripts were analyzed using Genetrix suite of microarray analysis tools. Cox regression and leave-n-out cross validation were used to derive and finalize the expression signatures. An effort was made compare individual prognostic potentials of the coding and non-coding signatures, and that of a signature that combined both features. Results: Standard pathologic prognosticators such as histologic subtype classification (alveolar versus embryonal) and PAX-FKHR fusion gene status were unable to predict outcome in this cohort (p=0.40 and 0.45, respectively). Cox regression analysis on 17,049 coding transcripts created a 42-gene meta-feature that was able to predict survival (p=0.00024). Leave-n-out cross validation of this meta-feature upheld its prognostic ability (p=0.00030). Analysis of probe set regions (PSRs) corresponding to unannotated “dark matter” transcripts identified a 32-PSR meta-feature that also predicted survival with greater significance than PSRs corresponding to coding transcripts (p<0.00001). To reduce feature redundancy, multiple PSRs interrogating the same genomic locus were replaced by a representative PSR that shrunk the meta-feature size to 24 PSRs, which was still able to predict survival better than the coding gene meta-feature (p<0.00001). A meta-feature that combined coding and non-coding RNA features retained its ability to predict outcome (p=0.00002), with non-coding RNA features contributing towards the bulk of its prognostic potential. Conclusions: A more concise non-coding RNA meta-feature was able to better predict outcome than a larger coding gene meta-feature in intermediate-risk RMS, where standard pathologic prognosticators failed. This suggests the role of non-coding transcripts in regulating and determining RMS biology and aggressiveness, and their potential to serve as novel prognostic indicators. Citation Format: Anirban P. Mitra, Jonathan D. Buckley, Sheetal A. Mitra, Elai Davicioni, James R. Anderson, Philipp Kapranov, Stephen X. Skapek, Douglas S. Hawkins, Timothy J. Triche. A non-coding RNA panel predicts intermediate-risk childhood rhabdomyosarcoma prognosis better than standard pathologic criteria and coding genes [abstract]. In: Proceedings of the AACR Special Conference on Noncoding RNAs and Cancer; 2012 Jan 8-11; Miami Beach, FL. Philadelphia (PA): AACR; Cancer Res 2012;72(2 Suppl):Abstract nr A23.

Security Model for Tree-based Routing in Wireless Sensor Networks: Structure and Evaluation

The need for securing Wireless Sensor Networks (WSNs) is essential especially in mission critical fields such as military and medical applications. Security techniques that are used to secure any network depend on the security requirements that should be achieved to protect the network from different types of attacks. Furthermore, the characteristics of wireless networks should be taken into consideration when applying security techniques to these networks. In this paper, energy efficient Security Model for Tree-based Routing protocols (SMTR) is proposed. In SMTR, different attacks that could face any tree-based routing protocol in WSNs are studied to design a security reference model that achieves authentication and data integrity using either Message Authentication Code (MAC) or Digital Signature (DS) techniques. The SMTR communication and processing costs are mathematically analyzed. Moreover, SMTR evaluation is performed by firstly, evaluating several MAC and DS techniques by applying them to tree-based routing protocol and assess their efficiency in terms of their power requirements. Secondly, the results of this assessment are utilized to evaluate SMTR phases in terms of energy saving, packet delivery success ratio and network life time.

PAPR Analytical Characterization and Reduced-PAPR Code Allocation Strategy for MC-CDMA Transmissions

In this paper, an approximate analytical expression for the peak-to-average power ratio (PAPR) of a Multi-Carrier Code Division Multiple Access (MC-CDMA) signal is derived. Then, it is demonstrated that the PAPR of a MC-CDMA system employing Walsh-Hadamard (WH) codes can be suitably reduced by resorting to a judicious strategy for the allocation of the spreading signature codes. Eventually, a low-complexity implementation of the proposed strategy is presented and the relevant benefits, in terms of peak signal occurrence and robustness against nonlinear distortions, is numerically assessed over conventional random allocation strategy.

Complete genome characterization of Genogroup II norovirus strains from India: Evidence of recombination in ORF2/3 overlap

Noroviruses (NoVs) are considered as important causative agents of non-bacterial acute gastroenteritis, worldwide. The data on NoV genomes, their diversity and evolution from Indian subcontinent are not available to date. The present study describes the characterization of full-length genomes of Indian NoV strains for the first time to establish their phylogenetic and evolutionary relationship with those circulating worldwide. Amplification of full-length genomes of three NoV strains (PC15, PC51 and PC52) was carried out using nine overlapping sets of forward and reverse primers. Full-length genomes of all of the three strains were characterized by phylogenetic, SimPlot, selection pressure and hydrophilicity analyses. The strain, PC15 was placed in the GII.4-Hunter subcluster. An intragenotype recombination event between ORFs 2 (new GII.4 variant) and 3 (Den Haag subcluster) of the strain, PC51 was detected for the first time in this study. The strain, PC52 showed the presence of commonly detected intergenotype recombination, GII.b/GII.3. A 16 amino-acid signature code (TDVVYYAGASQPRDDI) was identified in the ORF2 of recombinant GII.3 specificity strains, which may serve as a genetic marker for differentiation of these strains from non-recombinant GII.3 strains. The amino-acid substitutions in the ORF2 of PC51 and PC52 strains in comparison to the reference strains (Toyama1 and TV24) resulted in an increase in the hydrophilicity suggested alterations in the antigenic regions of Indian NoV strains. A unique pattern of amino-acid substitutions was observed within seven subclusters of GII.4 at 19 sites (including 13 sites under positive selection pressure) spanning entire ORF2. The study indicates adaptation of NoVs in the environment to escape the host immune response and to persist in the population. It also provides in-depth analyses of NoV genomes from India and determines the extent of conserved and variable features of the Indian NoV strains.

Spectral Feature Probabilistic Coding for Hyperspectral Signatures

Spectral signature coding (SSC) is generally performed by encoding spectral values of a signature across its spectral coverage followed by the Hamming distance to measure signature similarity. The effectiveness of such an SSC largely relies on how well the Hamming distance can capture spectral variations that characterize a signature. Unfortunately, in most cases, this Hamming-distance-based SSC does not provide sufficient discriminatory information for signature analysis because the Hamming distance does not take into account the band-to-band variation, in which case the Hamming distance can be considered as a memoryless distance. This paper extends the Hamming-distance-based SSC to an approach, referred to as spectral feature probabilistic coding (SFPC), which introduces a new concept into SSC that uses a criterion with memory to measure spectral similarity. It implements the well-known arithmetic coding (AC) in two ways to encode a signature in a probabilistic manner, called circular SFPC and split SFPC. The values resulting from the AC is then used to measure the distance between two spectral signatures. In order to demonstrate advantages of using AC-based SSC in signature analysis, a comparative analysis is also conducted against spectral binary coding.

Evidence for a novel coding sequence overlapping the 5'-terminal ~90 codons of the Gill-associated and Yellow head okavirus envelope glycoprotein gene

The genus Okavirus (order Nidovirales) includes a number of viruses that infect crustaceans, causing major losses in the shrimp industry. These viruses have a linear positive-sense ssRNA genome of ~26-27 kb, encoding a large replicase polyprotein that is expressed from the genomic RNA, and several additional proteins that are expressed from a nested set of 3'-coterminal subgenomic RNAs. In this brief report, we describe the bioinformatic discovery of a new, apparently coding, ORF that overlaps the 5' end of the envelope glycoprotein encoding sequence, ORF3, in the +2 reading frame. The new ORF has a strong coding signature and, in fact, is more conserved at the amino acid level than the overlapping region of ORF3. We propose that translation of the new ORF initiates at a conserved AUG codon separated by just 2 nt from the ORF3 AUG initiation codon, resulting in a novel 86 amino acid protein.

A newly combined code-designing method of two-dimensional signature codes for OCDMA system

A new kind of two-dimensional optical orthogonal code named ESPC/OCS is constructed, which uses the extend square prime code (ESPC) for time spreading and the one-coincidence sequence(OCS) for wavelength hopping. The performance of ESPC/OCS is analyzed and the mean value of cross-correlation is deduced. Meanwhile the bit error ratio (BER) for codes is simulated and compared. The simulation results show that given p and q, the BER of ESPC/OCS is reduced, and the capacity is enlarged, when the number of hopping codes p is increased. Given OCS (given q and d), when p is changed, only the capacity is changed, but the BER is almost the same. The performance of ESPC/OCS is better than that of PC/OCS.

Genetic diversity of genotype G1 rotaviruses co-circulating in western India

The rotavirus (RV) G1 strains represent the common genotype that causes diarrhea in humans. The aim of this study was to determine the genetic lineages of G1 RV strains circulating in western India during two different time periods, 1991–1994 and 2006 by molecular characterization of VP7 genes. The phylogenetic analysis of VP7 genes showed clustering of G1 strains into lineages I (96.4%) and VIII (3.6%) in 1991–1994 and I (96.2%) and II (3.8%) in 2006. The sublineage IA was predominant (96.4%) in the years 1991–1994, however, was detected only in 44.4% of the strains in 2006 co-circulating with other sublineages IB (44.4%), IC (3.7%), IE (3.7%) and IIB (3.7%). The amino acid substitutions were noted in the previously identified signature codes of sublineages IB and IIB at positions 75 and 55, respectively. The differentiation marker (Q) described for sublineage IB at position 16 was replaced by I in all Indian strains clustered in sublineage IB. The study reports the characterization of G1 RV strains on the basis of distinct lineages and sublineages from India and emphasizes continuous monitoring on the diversity of G1 strains across the Indian population.

Bounds on the Sum Capacity of Synchronous Binary CDMA Channels

In this paper, we obtain a family of lower bounds for the sum capacity of Code Division Multiple Access (CDMA) channels assuming binary inputs and binary signature codes in the presence of additive noise with an arbitrary distribution. The envelope of this family gives a relatively tight lower bound in terms of the number of users, spreading gain and the noise distribution. The derivation methods for the noiseless and the noisy channels are different but when the noise variance goes to zero, the noisy channel bound approaches the noiseless case. The behavior of the lower bound shows that for small noise power, the number of users can be much more than the spreading gain without any significant loss of information (overloaded CDMA). A conjectured upper bound is also derived under the usual assumption that the users send out equally likely binary bits in the presence of additive noise with an arbitrary distribution. As the noise level increases, and/or, the ratio of the number of users and the spreading gain increases, the conjectured upper bound approaches the lower bound. We have also derived asymptotic limits of our bounds that can be compared to a formula that Tanaka obtained using techniques from statistical physics; his bound is close to that of our conjectured upper bound for large scale systems.

Code-modulated path-sharing multi-antenna receivers: theory and analysis

Conventional multi-antenna receiver front-ends require multiple RF/baseband chains and analog-to-digital converters (ADC). This increases power consumption and chip area substantially. In this letter, we introduce a new Code-Modulated Path-Sharing Multi-Antenna (CPMA) receiver architecture suitable for any multi-antenna scheme including spatial multiplexing, spatial diversity, and beamforming. The receiver uses code modulation to distinguish the antenna signals before combining them in the analog domain. The combined signal propagates through shared-path blocks and all the original signals are later recovered in the digital domain for further processing. Due to the spread spectrum nature of code modulation, a larger bandwidth is needed for the blocks in the shared path. To alleviate this effect, the use of non-orthogonal coding is examined. An effective channel matrix is derived and the system capacity is evaluated in terms of the cross-correlation between signature codes. Implementation and code selection issues are discussed. Analysis and simulation results indicate that by properly selecting non-orthogonal code sets, the spreading factor, and therefore, the overall analog signal bandwidth is reduced while incurring minimal performance degradation.

Differential decorrelator: a new approach for designing CDMA linear detector

The systems that are designed based on CDMA are suffering from a multiple access interference problem. The decorrelator CDMA detector is a linear detector that can cancel the MAI but with channel noise enhancement. The complexity of the decorrelator is a linear function in the number of the system's users. In this research, a new detector is proposed that can cancel the MAI in the received CDMA signal with a complexity that is independent on the number of the system's users. The new detector does not need to know the users' signature codes. Also, it consists of two matched filter only. No correlation matrix is required. This simple structure reduces the complexity of the proposed CDMA detector if it is compared with the conventional decorrelator detector. The new detector is based on some mathematical operations on the output signals from two different matched filters. The detector idea is based on the symmetry property of the signatures' codes correlation matrix however; it does not need to know this matrix. The algorithm is valid as long as the correlation matrix is symmetry. It can work with synchronous and asynchronous system models.

Unipolar codes for optical spectral-amplitude code-division multiple-access systems based on combinatorial designs

A novel class of optical signature codes based on combinatorial designs is proposed for optical spectral-amplitude code-division multiple-access (CDMA) systems. It is applicable to both synchronous and asynchronous incoherent optical CDMA and is compatible with both frequency-encoded and time-spreading schemes. Simplicity of construction, larger code cardinality and larger flexibility in cross-correlation (CC) control make the proposed code family an interesting candidate for future optical CDMA applications that require a large number of simultaneous users. It has been shown that the system performance can be significantly improved by using the proposed codes with ideal in-phase CC in preference to Hadamard codes.

A case for a CUG-initiated coding sequence overlapping torovirus ORF1a and encoding a novel 30 kDa product

The genus Torovirus (order Nidovirales) includes a number of species that infect livestock. These viruses have a linear positive-sense ssRNA genome of ~25-30 kb, encoding a large polyprotein that is expressed from the genomic RNA, and several additional proteins expressed from a nested set of 3'-coterminal subgenomic RNAs. In this brief report, we describe the bioinformatic discovery of a new, apparently coding, ORF that overlaps the 5' end of the polyprotein coding sequence, ORF1a, in the +2 reading frame. The new ORF has a strong coding signature and, in fact, is more conserved at the amino acid level than the overlapping region of ORF1a. We propose that the new ORF utilizes a non-AUG initiation codon - namely a conserved CUG codon in a strong Kozak context - upstream of the ORF1a AUG initiation codon, resulting in a novel 258 amino acid protein, dubbed '30K'.

Analysis of the coding potential of the partially overlapping 3' ORF in segment 5 of the plant fijiviruses

The plant-infecting members of the genus Fijivirus (family Reoviridae) have linear dsRNA genomes divided into 10 segments, two of which contain two substantial and non-overlapping ORFs, while the remaining eight are apparently monocistronic. However, one of these – namely segment 5 – contains a second long ORF (~200+ codons) that overlaps the 3' end of the major ORF (~920–940 codons) in the +1 reading frame. In this report, we use bioinformatic techniques to analyze the pattern of base variations across an alignment of fijivirus segment 5 sequences, and show that this 3' ORF has a strong coding signature. Possible translation mechanisms for this unusually positioned ORF are discussed.

The Importance of Odorant Conformation to the Binding and Activation of a Representative Olfactory Receptor

Olfactory receptors (ORs) form a large family of G protein-coupled receptor proteins (GPCRs) responsible for sensing the ambient chemical environment. The molecular recognition strategies used by ORs to detect and distinguish odorant molecules are unclear. Here, we investigated the variable of odorant carbon chain conformation for an established odorant-OR pair: n-octanal and rat OR-I7. A series of conformationally restricted octanal mimics were tested on live olfactory sensory neurons (OSNs). Our results support a model in which unactivated OR-I7 binds aliphatic aldehydes indiscriminately, and then applies conformational and length filters to distinguish agonists from antagonists. Specific conformers are proposed to activate OR-I7 by steric buttressing of an OR activation pocket. Probing endogenously expressed rat OSNs with octanal and constrained mimics furnished evidence that odorant conformation contributes to an odorant's unique olfactory code signature.

Adaptive binary signature design for code-division multiplexing

When data symbols modulate a signature waveform to move across a channel in the presence of disturbance, the signature that maximizes the signal-to-interference-plus-noise ratio (SINR) at the output of the maximum-SINR filter is the smallest-eigenvalue eigenvector of the disturbance autocovariance matrix. In digital communication systems the signature alphabet is finite and digital signature optimization is NP-hard. In this paper, we present a formal search procedure of cost, upon eigenvector decomposition, log-linear in the signature code length that returns the maximum-SINR binary signature vector near arcs of least SINR decrease from the real maximum SINR solution in the Euclidean vector space. The quality of the proposed adaptive binary designs is measured against the theoretical upper bound of the complex/real eigenvector maximizer.

Bioinformatic analysis suggests that a conserved ORF in the waikaviruses encodes an overlapping gene

The genus Waikavirus belongs to the order Picornavirales, whose members all use a polyprotein expression strategy. With the exception of Theiler's virus, overlapping genes are essentially unknown in the order. Recently, we reported experimental verification for a new short overlapping coding sequence (CDS) in the Potyviridae-a family in which overlapping genes were previously unknown. Using the same bioinformatics software (MLOGD), we have identified an approximately 89-codon conserved open reading frame (ORF) with a strong coding signature in members of the genus Waikavirus. The ORF overlaps the polyprotein ORF but is in the +1 reading frame. Here, we describe the bioinformatic analysis.

Performance enhancement of spectral‐amplitude coding OCDMA system using novel PPM signalling

AbstractA spectral‐amplitude coding (SAC) optical code‐division multiple‐access (OCDMA) system with M‐ary pulse‐position modulation (PPM) signalling is investigated. Novel combinatorial construction of optical signature codes is also presented, as that is applicable to both synchronous and asynchronous incoherent OCDMA. A union upper bound on the probability of error is then derived and the performance characteristics are discussed in the presence of multiple‐access interference (MAI) and intensity noise. The numerical results show that the bit‐error performance of the OCDMA system with proposed PPM coding outperforms that associated with on—off keying (OOK). Copyright © 2008 John Wiley & Sons, Ltd.

Detecting anomalous CO2 flux using space borne spectroscopy

Over the time-scale, earth's atmospheric CO2 concentration has varied and that is mostly determined by balance among the geochemical processes including burial of organic carbon in sediments, silicate rock weathering and volcanic activity. The best recorded atmospheric CO2 variability is derived from Vostok ice core that records last four glacial/interglacial cycles. The present CO2 concentration of earth's atmosphere has exceeded far that it was predicted from the ice core data. Other than rapid industrialization and urbanization since last century, geo-natural hazards such as volcanic activity, leakage from hydrocarbon reservoirs and spontaneous combustion of coal contribute a considerable amount of CO2 to the atmosphere. Spontaneous combustion of coal is common occurrence in most coal producing countries and sometimes it could be in an enormous scale. Remote sensing has already proved to be a significant tool in coalfire identification and monitoring studies. However, coalfire related CO2 quantification from remote sensing data has not endeavoured yet by scientific communities because of low spectral resolution of commercially available remote sensing data and relatively sparse CO2 plume than other geological hazards like volcanic activity. The present research has attempted two methods to identify the CO2 flux emitted from coalfires in a coalmining region in north China. Firstly, a band rationing method was used for column atmospheric retrieval of CO2 and secondly atmospheric models were simulated in fast atmospheric signature code (FASCOD) to understand the local radiation transport and then the model was implemented with the inputs from hyperspectral remote sensing data. It was observed that retrieval of columnar abundance of CO2 with the band rationing method is faster as less simulation required in FASCOD. Alternatively, the inversion model could retrieve CO2 concentration from a (certain) source because it excludes the uncertainties in the higher altitude.