Crypt analysis of two time pads in case of compressed speech

Keystream reuse, also known as the two time pad problem, is a well known weakness in stream ciphers. The implementers of the cryptographic algorithms are still underestimating this threat. The keystream reuse exploitation techniques presented so far assume the underlying plaintext to be textual data and all the heuristics presented previously are based on the language characteristics of the underlying text based data, which fail when compression is applied on the plaintext before encryption. This paper presents exploitation techniques for two time pads in case of stream ciphered digitized and compressed speech signals. In this paper we show that how an adversary can automatically recover the digitized speech signals encrypted under the same keystream provided the language (e.g. English) and digital encoding/compression scheme details of the underlying speech signals are known. Our technique of cryptanalysis is based on the modeling of the speech parameters by exploiting the inter frame correlations between each components of the speech vectors in different frames and then using these models to decode the two speech signals in the keystream reuse scenario. The technique is flexible enough to incorporate all modern speech coding schemes based on parameter or hybrid encoding and compression techniques. The simulation experiments have showed promising results for most of the present day speech digitization and compression techniques.     

Immune recognition of botulinum neurotoxin type A: regions recognized by T cells and antibodies against the protective H(C) fragment (residues 855-1296) of the toxin

Botulism toxicity is caused by botulinum neurotoxins (BoNTs), a group of protein neurotoxins produced by Clostridium botulinum. Recent studies have shown that immunization with a C-terminal fragment [H(C), residues 855-1296] of BoNT type A (BoNT/A) affords excellent protection against BoNT/A toxicity. The present work was carried out in order to map the molecular and cellular immunological recognition of H(C). We have previously described the synthesis of 31 overlapping peptides encompassing the entire H(C)-fragment of BoNT/A. These peptides were employed in this study to localize the continuous regions recognized by T cells and by antibodies (Abs) generated in two mouse strains against H(C). T cells from SJL that had been primed with H(C) gave a strong proliferative response to challenge in vitro with each of the six peptides spanning residues 897-985 and a lower response to peptide 1051- 1069. While H(C)-primed T cells of BALB/c recognized three regions residing within residues 939-957, 1009-1027 and 1135-1153 (strong). Recognition regions by Abs in SJL or BALB/c anti-H(C) antisera essentially overlapped. However, the level of Abs bound to each region differed between the two strains. These common or similar recognition regions by the two strains were: 855-915 (SJL) or 855-901 (BALB/c); 939-957; 967-1013 (BALB/c) or 981-1013 (SJL); 1051-1069; 1079-1111 (BALB/c) or 1093-1125 (SJL); 1177-1195; and 1275-1296. In addition, BALB/c recognized region 1135-1153. Some of these regions show considerable sequence similarity in BoNT types B and E and, therefore, H(C) of these two BoNTs might offer protection against the correlate clostridial toxins.     

Application of hammerhead ribozymes for structural studies of ribosomal 5S RNAs

We evaluated the possibility that distinct proteolytic pathways contribute to the down-regulation of a novel (epsilon) or conventional (alpha) isoform of protein kinase C (PKC) in nonimmortalized human fibroblasts. Inhibitors of calpains and other cysteine proteinases, vesicle trafficking, or lysosomal proteolysis did not affect the down-regulation of PKC-alpha or -epsilon produced by bryostatin 1 (Bryo). Lactacystin (Lacta) and certain terminal aldehyde tripeptides or tetrapeptides, which selectively inhibit the proteasome, preserved substantial PKC-alpha and -epsilon protein from down-regulation by Bryo or phorbol-12-myristate-13-acetate. Lacta preserved active kinase in vivo, as shown by the retention of Bryo-induced autophosphorylated PKC-alpha. Concomitant with down-regulation, Bryo produced PKC-alpha and -epsilon species that were larger than the native proteins (80 and 90 kDa, respectively). Western blot analysis showed that the larger PKC-alpha species were ubiquitinylated. Treatment with Bryo plus Lacta synergistically increased multiubiquitinylated PKC-alpha, as expected if Bryo induces ubiquitinylation of PKC-alpha and Lacta blocks its degradation. Bryo also produced a 76-kDa, nonphosphorylated form of PKC-alpha and an 86-kDa form of PKC-epsilon. Phosphatase inhibitors decreased production of 76- and 86-kDa PKC-alpha and -epsilon by Bryo and preserved 80- and 90-kDa PKC-alpha and -epsilon, respectively. Our results suggest that the down-modulation of PKC-alpha and -epsilon occurs principally via the ubiquitin/ proteasome pathway. Dephosphorylation seems to predispose PKC to ubiquitinylation.     

Noncanonical conformation of nucleic acids: structure with slipped-loops, occurring in DNA oligonucleotides

A HPLC method was developed and validated for the quantitation of 9-cis-retinoic acid (ALRT1057) and its major metabolite, 4-oxo-9-cis-retinoic acid (LG100182) in human plasma. Samples were buffered and extracted with methyl-tert-butyl-ether. The analytes and an I.S. were separated on a C18 HPLC column using a shallow gradient of 70-89% organic solvent. The analytes were quantitated by UV detection at 348 nm. Selectivity against endogenous compounds and potential metabolites (retinol, all trans-, 13-cis-, and 4-hydroxy-9-cis-retinoic acid) was demonstrated. The run time was 29 min. The standard curve was linear from 2.5 to 450 ng ml-1. Interassay precision for both analytes in quality control samples was less than 5.0% RSD. Accuracy was within 11.0% RE for both compounds. Analyte stability during sample storage, extraction processing, and chromatography was established. Method ruggedness was tested by two analysts and on two HPLC systems. This method has been applied to the quantitation of clinical samples.     

Apoprotein structure in the LH2 complex from Rhodopseudomonas acidophila strain 10050: modular assembly and protein pigment interactions

The refined structure of the peripheral light-harvesting complex from Rhodopseudomonas acidophila strain 10050 reveals a membrane protein with protein-protein interactions in the trans-membrane region exclusively of a van der Waals nature. The dominant factors in the formation of the complex appear to be extramembranous hydrogen bonds (suggesting that each apoprotein must achieve a fold close to its final structure in order to oligomerize), protein-pigment and pigment-pigment interactions within the membrane-spanning region. The pigment molecules are known to play an important role in the formation of bacterial light-harvesters, and their extensive mediation of structural contacts within the membrane bears this out. Amino acid residues determining the secondary structure of the apoproteins influence the oligomeric state of the complex. The assembly of the pigment array is governed by the apoproteins of LH2. The particular environment of each of the pigment molecules is, however, influenced directly by few protein contacts. These contacts produce functional effects that are not attributable to a single cause, e.g. the arrangement of an overlapping cycle of chromophores not only provides energy delocalisation and storage properties, but also has consequences for oligomer size, pigment distortion modes and pigment chemical environment, all of which modify the precise function of the complex. The evaluation of site energies for the pigment array requires the consideration of a number of effects, including heterogeneous pigment distortions, charge distributions in the local environment and mechanical interactions.     

PAPR reduction in mobile WiMAX: a novel DST precoding based random interleaved OFDMA uplink system

Mobile WiMAX is a 3rd generation broadband wireless technology that enables the convergence of mobile and fixed broadband networks through a wide area radio-access. Since January 2007, the IEEE 802.16 working group has been developing a new amendment the IEEE 802.16 standard i.e. IEEE 802.16 m as an advanced air interface to meet the requirements of ITU-R/IMT-Advanced for 4G systems. The mobile WiMAX air interface adopts orthogonal frequency division multiple access (OFDMA) as multiple access technique for its uplink and downlink to improve signal performance affected by multipath distortion. All OFDMA based networks, including mobile WiMAX, experience the problem of high peak-to-average power ratio (PAPR). This paper presents a discrete-sine-transform precoding technique based random-interleaved OFDMA (RI-OFDMA) uplink system for PAPR reduction in mobile WiMAX. The PAPR of proposed system is analyzed with root-raised-cosine pulse shaping filter to keep out of band radiation low and to fulfill the spectrum mask requirements. Simulation results show that, the proposed system has low PAPR compared to the Hadamard transform precoded RI-OFDMA uplink systems and the conventional RI-OFDMA uplink systems.     

Cystic fibrosis in Malay children--a report of three cases

A staining device for sectioned material supported on grids for viewing at the Transmission Electron Microscope is described. The method based in a double side sticky tape is inexpensive, rapid and clean. By using only pipettes and a double side sticky tape the best solution to the tedious problems of sections staining is obtained. The tape is discarded and the staining solution too. Precipitates have not been observed.     

Differential behavior of (25R)-5,6-epoxyspirostan-22 alpha-O-3 beta-ol and (25R)-5,6-epoxyspirostan-22 alpha-O-3 beta, 4 beta-diol toward Dowex

The acid-catalyzed hydrolytic cleavage of the 5,6-epoxyspirostane derivatives by the cation exchange resin Dowex 50W X8 has been exploited with the goal of developing synthetic protocols toward 3,4,5,6-polyhydroxyspirostane analogs that can serve as intermediates to potential biologically active compounds. Whereas the diastereomers (25R)-5 alpha, 6 alpha-epoxyspirostan-22 alpha-O-3 beta-ol and (25R)-5 beta, 6 beta-epoxyspirostan-22 alpha-O-3 beta-ol yield two products, (25R)-6 beta-methoxyspirostan-22 alpha-O-3 beta, 5 alpha-diol and (25R)-spirostan-22 alpha-O-3 beta, 5 alpha, 6 beta-triol on Dowex treatment in water-methanol, the alpha- and beta-diastereomers of the 5,6-epoxy derivative of 3 beta, 4 beta-diol provide a single product, (25R)-3 beta, 6 beta-dihydroxy-5 alpha-spirostan-4-one, in good yields. The structures of these products have been confirmed using 1H NMR, 13C NMR, and 1H-1H J-correlated spectroscopies. Multifunctional product formation suggests tremendous utility of Dowex in steroid synthesis. The product formation has been rationalized on the basis of differential conformational constraints of the A/B rings of the different epoxides in directing the reaction course. The reaction shows an interesting example of stereoelectronic effect of a single hydroxy group in discriminating solvent participation.     

CD34+, kit+, rhodamine123(low) phenotype identifies a marrow cell population highly enriched for human hematopoietic stem cells

We hypothesized that human hematopoietic cells displaying a CD34+, kit-, rhodamine123(low) phenotype would be highly enriched for cells with stem-like properties. To test this hypothesis, we employed fluorescence activated cell sorting (FACS) to isolate cells with this phenotype from normal light density marrow mononuclear cells (MNC). CD34+, kit+, rhodamine123(low) cells comprised from 0.05-0.01% of the total MNC population. They were small, had scant cytoplasm, and contained nuclei with dense, hyperchromatic chromatin and inconspicuous nucleoli. Additional immunophenotyping revealed that these cells were CD33-, CD38-, CD20-, and glycophorin A-. When plated in semisolid cultures containing optimal concentrations of IL-3, GM-CSF, KL, EPO, IL-6, and IL-1 these cells did not form colonies. However, when cultured over irradiated stromal cells, cobblestone areas were observed to form after 3 weeks, and harvested cells were able to initiate long-term cultures. To further demonstrate that these cells were indeed stem like, we also tested their ability to engraft and mature in immunocompromised (SCID) mice. Irradiated (400 cGy) SCID mice were transplanted with 2 x 10(3) candidate stem cells which were then injected with recombinant human growth factors every other day. Two months post-transplant the animals were sacrificed. PCR and FACS analysis of marrow and spleen cell samples revealed the presence of cells expressing human CD45 consistent with engraftment of human stem cells and the establishment of murine-human chimerism. Moreover, MNC isolated from transplanted mice formed unambiguously human BFU-E, CFU-GM and B cell colonies when stimulated with the appropriate growth factors. Accordingly, we have identified a relatively rapid and simple mechanism for isolating primitive human hematopoietic cells with stem cell-like properties. We anticipate that this strategy will be useful for experimental and therapeutic applications that require human stem cells in quantity.