Light and Strong SiC Networks

The directional freezing of microfiber suspensions is used to assemble highly porous (porosities ranging between 92% and 98%) SiC networks. These networks exhibit a unique hierarchical architecture in which thin layers with honeycomb‐like structure and internal strut length in the order of 1–10 μm in size are aligned with an interlayer spacing ranging between 15 and 50 μm. The resulting structures exhibit strengths (up to 3 MPa) and stiffness (up to 0.3 GPa) that are higher than aerogels of similar density and comparable to other ceramic microlattices fabricated by vapor deposition. Furthermore, this wet processing technique allows the fabrication of large‐size samples that are stable at high temperature, with acoustic impedance that can be manipulated over one order of magnitude (0.03–0.3 MRayl), electrically conductive and with very low thermal conductivity. The approach can be extended to other ceramic materials and opens new opportunities for the fabrication of ultralight structures with unique mechanical and functional properties in practical dimensions.     

Digital fingerprinting codes: problem statements, constructions, identification of traitors

We consider a general fingerprinting problem of digital data under which coalitions of users can alter or erase some bits in their copies in order to create an illegal copy. Each user is assigned a fingerprint which is a word in a fingerprinting code of size M (the total number of users) and length n. We present binary fingerprinting codes secure against size-t coalitions which enable the distributor (decoder) to recover at least one of the users from the coalition with probability of error exp(-/spl Omega/(n)) for M=exp(/spl Omega/(n)). This is an improvement over the best known schemes that provide the error probability no better than exp(-/spl Omega/(n/sup 1/2/)) and for this probability support at most exp(O(n/sup 1/2/)) users. The construction complexity of codes is polynomial in n. We also present versions of these constructions that afford identification algorithms of complexity poly(n)=polylog(M), improving over the best previously known complexity of /spl Omega/(M). For the case t=2, we construct codes of exponential size with even stronger performance, namely, for which the distributor can either recover both users from the coalition with probability 1-exp(/spl Omega/(n)), or identify one traitor with probability 1.     

On computing the weight spectrum of cyclic codes

Two deterministic algorithms of computing the weight spectra of binary cyclic codes are presented. These algorithms have the lowest known complexity for cyclic codes. For BCH codes of lengths 63 and 127, several first coefficients of the weight spectrum in number sufficient to evaluate the bounded distance decoding error probability are computed     

New upper bounds on generalized weights

We derive new asymptotic upper bounds on the generalized weights of a binary linear code of a given size. We also prove some asymptotic results on the distance distribution of binary codes     

Synthesis and characterization of polyurethane/titanium dioxide nanocomposites obtained by in situ polymerization

The development of new polymeric and polymeric based materials is fundamental to meet the market demands. This work aims the synthesis and characterization of polyurethane/titanium dioxide nanocomposite, using low cost commercial raw materials. Nanocomposites were synthesized by in situ polymerization reactions in which titanium dioxide were added in the following proportions, by weight, in relation to the mass obtained from the pure polymer: 0.5, 1.0, 2.0, 3.0, 5.0, 7.0, and 10.0 %. These reactions were based in poli (ε-caprolactone) and 1,6-diisocyanatohexane. The materials were characterized by infrared spectroscopy Fourier transform, scanning electron microscopy, differential scanning calorimetry analysis, thermogravimetric analysis, dynamic mechanical thermal analysis, and UV–Vis spectroscopy. Based on the obtained results it was concluded that the nanocomposites synthesized by in situ polymerization presented, in general, thermal properties (degradation temperature) and mechanical properties higher than the pure polymer.     

Beef tallow biodiesel produced in a pilot scale

In the present work, the process of biodiesel production in a pilot plant has been studied using beef tallow as raw materials with methanol and potassium hydroxide as catalyst. The biodiesel quality is regulated by Brazilian specifications (Resolution 42) by the National Agency of Petroleum (ANP). The alkaline transesterification of animal fat with methanol produces a biodiesel with high quality and also with a good conversion rate. The process is possible but the economical viability must be improved by recovering methanol and glycerin. The obtained results have been used for industrial scale up of the process.     

Molecular Mechanisms of Skewed X-Chromosome Inactivation in Female Hemophilia Patients—Lessons from Wide Genome Analyses

Introduction: Hemophilia A (HA) is an X-linked bleeding disorder caused by factor VIII (FVIII) deficiency or dysfunction due to F8 gene mutations. HA carriers are usually asymptomatic because their FVIII levels correspond to approximately half of the concentration found in healthy individuals. However, in rare cases, a carrier may exhibit symptoms of moderate to severe HA primarily due to skewed inactivation of her non-hemophilic X chromosome. Aim: The aim of the study was to investigate X-chromosome inactivation (XCI) patterns in HA carriers, with special emphasis on three karyotypically normal HA carriers presenting with moderate to severe HA phenotype due to skewed XCI, in an attempt to elucidate the molecular mechanism underlying skewed XCI in these symptomatic HA carriers. The study was based on the hypothesis that the presence of a pathogenic mutation on the non-hemophilic X chromosome is the cause of extreme inactivation of that X chromosome. Methods: XCI patterns were studied by PCR analysis of the CAG repeat region in the HUMARA gene. HA carriers that demonstrated skewed XCI were further studied by whole-exome sequencing (WES) followed by X chromosome-targeted bioinformatic analysis. Results: All three HA carriers presenting with the moderate to severe HA phenotype due to skewed XCI were found to carry pathogenic mutations on their non-hemophilic X chromosomes. Patient 1 was diagnosed with a frameshift mutation in the PGK1 gene that was associated with familial XCI skewing in three generations. Patient 2 was diagnosed with a missense mutation in the SYTL4 gene that was associated with familial XCI skewing in two generations. Patient 3 was diagnosed with a nonsense mutation in the NKAP gene that was associated with familial XCI skewing in two generations. Conclusion: Our results indicate that the main reason for skewed XCI in our female HA patients was negative selection against cells with a disadvantage caused by an additional deleterious mutation on the silenced X chromosome, thus complicating the phenotype of a monogenic X-linked disease. Based on our study, we are currently offering the X inactivation test to symptomatic hemophilia carriers and plan to expand this approach to symptomatic carriers of other X-linked diseases, which can be further used in pregnancy planning.     

Exercise as stigma management for individuals with onset-controllable and onset-uncontrollable spinal cord injury.

Studies have suggested that individuals with physical disabilities are often stigmatized and are perceived to possess less favorable physical and psychological characteristics than individuals without disability. Purpose: To investigate whether able-bodied adults' perceptions of people with different causes of spinal cord injury (SCI) are influenced by physical activity status information. Method and Participants: Each participant (N = 198) read all five vignettes describing individuals with SCI who had varying levels of physical activity participation and cause of injury information (e.g., onset-uncontrollable [hit by impaired driver] and onset-controllable [caused by impaired driving]). After reading each vignette, participants completed a 12-item Warmth and Competence Questionnaire to evaluate each target. One-way repeated measures multivariate analyses of variance were conducted to examine the within-subjects differences. Results: Physically active individuals with onset-uncontrollable SCI were rated most favorably on warmth and competence. Physically active individuals with onset-controllable SCI also were rated more favorably on warmth and competence than physically inactive targets with onset-controllable SCI. Conclusion: A physically active lifestyle may be beneficial in managing the stigma experienced by individuals with both onset-controllable and onset-uncontrollable SCI. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Concatenated codes: serial and parallel

An analogy is examined between serially concatenated codes and parallel concatenations whose interleavers are described by bipartite graphs with good expanding properties. In particular, a modified expander code construction is shown to behave very much like Forney's classical concatenated codes, though with improved decoding complexity. It is proved that these new codes achieve the Zyablov bound /spl delta//sub Z/ on the minimum distance. For these codes, a soft-decision, reliability-based, linear-time decoding algorithm is introduced, that corrects any fraction of errors up to almost /spl delta//sub Z//2. For the binary-symmetric channel, this algorithm's error exponent attains the Forney bound previously known only for classical (serial) concatenations.     

On the Fingerprinting Capacity Under the Marking Assumption

We address the maximum attainable rate of fingerprinting codes under the marking assumption, studying lower and upper bounds on the value of the rate for various sizes of the attacker coalition. Lower bounds are obtained by considering typical coalitions, which represents a new idea in the area of fingerprinting and enables us to improve the previously known lower bounds for coalitions of size two and three. For upper bounds, the fingerprinting problem is modeled as a communications problem. It is shown that the maximum code rate is bounded above by the capacity of a certain class of channels, which are similar to the multiple-access channel (MAC). Converse coding theorems proved in the paper provide new upper bounds on fingerprinting capacity. It is proved that capacity for fingerprinting against coalitions of size two and three over the binary alphabet satisfies and , respectively. For coalitions of an arbitrary fixed size , we derive an upper bound on fingerprinting capacity in the binary case. Finally, for general alphabets, we establish upper bounds on the fingerprinting capacity involving only single-letter mutual information quantities.