A Generic attack on CubeHash, a SHA-3 candidate

A secure cryptographic hashing function should be resistant to three different scenarios: First, a cryptographic hashing function must be preimage resistant, that is, it should be infeasible for an attacker to construct a message such that it produces a known hash output value. Second, a cryptographic hashing function must be second preimage resistant, or it should be infeasible for an attacker to construct a message such that it has the same hash output value as another known message. Third, a cryptographic hashing function must be collision resistant, which means that it should be infeasible for an attacker to find any two different messages such that their hash output values are the same. The current Secure Hash Algorithm (SHA) family, namely SHA-1 and SHA-2, were designed by the National Security Agency (NSA) and published by the National Institute of Standards and Technology (NIST). Recent advances in cryptanalysis of hash functions have led to concerns about the collision resistance in the SHA family. To address these concerns, NIST has opened a public worldwide competition known as the SHA-3 competition to find the new hash function, which will become SHA-3. Each candidate hash function is scrutinized by the public, and candidates with found weaknesses are dropped from advancing to the next rounds of the competition. The goal is that the strongest hash function will emerge at the end of the competition, and this hash function will be free for everyone to use. This thesis implemented a generic attack against the collision resistance of small variants of one candidate in the SHA-3 competition, CubeHash. A unique hash-chaining approach was used to find the collisions, and the parallelization of several FPGAs lead to parallelization measurements and analysis to see if a linear speedup could be obtained

The effects of premenstrual syndrome on women with mental disabilities

Studies have shown that P.M.S. has a negative effect for women on many aspects of life. P.M.S. seems to affect social situations, family life, stress, mood, substance abuse, and crime. The purpose of this one way analysis study is to evaluate the effects of P.M.S. on women with mental disabilities with non-compliant behaviors. Fifty women, whose intelligence quotient levels range between severe and profound, who reside in an institution for individuals with mental disabilities were selected for this study. Each woman has some type of non-compliant behavior. Each female has been placed on a behavior modification program plan to reduce these behaviors. When these specified behaviors occur, the behaviors are marked on a frequency sheet in compliance with the program plan. Recording of the data in this study was accomplished through the use of frequency sheets used with the behavior modification program plan. The results of this dependent study was tested using a t-test. The results of the statistical testing showed no significant difference between pre-menstrual and post-menstrual behavior

Automatic signal range selector for metering devices Patent

Voltage range selection apparatus for sensing and applying voltages to electronic instruments without loading signal sourc

Performance assessment of low pressure nuclear thermal propulsion

A low pressure nuclear thermal propulsion (LPNTP) system, which takes advantage of hydrogen dissociation/recombination, was proposed as a means of increasing engine specific impulse (Isp). The effect of hydrogen dissociation/recombination on LPNTP Isp is examined. A two-dimensional computer model was used to show that the optimum chamber pressure is approximately 100 psia (at a chamber temperature of 3,000 K), with an Isp approximately 15 s higher than at 1,000 psia. At high chamber temperatures and low chamber pressures, the increase in Isp is due to both lower average molecular weights caused by dissociation and added kinetic energy from monatomic hydrogen recombination. Monatomic hydrogen recombination increases the Isp more then hydrogen dissociation. Variations in the mole fraction of monatomic hydrogen are similar to variations in static pressure along the axial nozzle position. Most recombination occurs close to the nozzle throat. Practical variations in nozzle geometry have minimal impact on recombination. Other models which can simulate a wider range of nozzle designs should be used in the future. The uncertainty of the hydrogen kinetic reaction rates at high temperatures (approximately 3,000 K) affects the accuracy of the analysis and should be verified with simple bench tests

Mercaptan-Disulfide Interchange Reactions

Chemistr

Affordable Development and Qualification Strategy for Nuclear Thermal Propulsion

A number of recent assessments have confirmed the results of several earlier studies that Nuclear Thermal Propulsion (NTP) is a leading technology for human exploration of Mars. It is generally acknowledged that NTP provides the best prospects for the transportation of humans to Mars in the 2030's. Its high Isp coupled with the high thrusts achievable, allow reasonable trip times, thereby alleviating concerns about space radiation and "claustrophobia" effects. NASA has embarked on the latest phase of the development of NTP systems, and is adopting an affordable approach in response to the pressure of the times. The affordable strategy is built on maximizing the use of the large NTP technology base developed in the 1950's and 60's. The fact that the NTP engines were actually demonstrated to work as planned, is a great risk reduction feature in its development. The strategy utilizes non-nuclear testing to the fullest extent possible, and uses focused nuclear tests for the essential qualification and certification tests. The perceived cost risk of conducting the ground tests is being addressed by considering novel testing approaches. This includes the use of boreholes to contain radioactive effluents, and use of fuel with very high retention capability for fission products. The use of prototype flight tests is being considered as final steps in the development prior to undertaking human flight missions. In addition to the technical issues, plans are being prepared to address the institutional and political issues that need to be considered in this major venture. While the development and deployment of NTP system is not expected to be cheap, the value of the system will be very high, and amortized over the many missions that it enables and enhances, the imputed costs will be very reasonable. Using the approach outlined, NASA and its partners, currently the DOE, and subsequently industry, have a good chance of creating a sustained development program leading to human missions to Mars within the next few decades

Sporormiella as a tool for detecting the presence of large herbivores in the Neotropics

The reliability of using the abundance of Sporormiella spores as a proxy for the presence and abundance of megaherbivores was tested in southern Brazil. Mud-water interface samples from nine lakes, in which cattle-use was categorized as high, medium, or low, were assayed for Sporormiella representation. The sampling design allowed an analysis of both the influence of the number of animals using the shoreline and the distance of the sampling site from the nearest shoreline. Sporormiella was found to be a reliable proxy for the presence of large livestock. The concentration and abundance of spores declined from the edge of the lake toward the center, with the strongest response being in sites with high livestock use. Consistent with prior studies in temperate regions, we find that Sporormiella spores are a useful proxy to study the extinction of Pleistocene megafauna or the arrival of European livestock in Neotropical landscapes

The CF-CIRC study: a French collaborative study to assess the accuracy of Cystic Fibrosis diagnosis in neonatal screening

BACKGROUND: Cystic fibrosis (CF) is caused by mutations in the gene encoding for the CF transmembrane conductance regulator (CFTR) protein, which acts as a chloride channel after activation by cyclic AMP (cAMP). Newborn screening programs for CF usually consist of an immunoreactive trypsinogen (IRT) assay, followed when IRT is elevated by testing for a panel of CF-causing mutations. Some children, however, may have persistent hypertrypsinogenemia, only one or no identified CFTR gene mutation, and sweat chloride concentrations close to normal values. In vivo demonstration of abnormal CFTR protein function would be an important diagnostic aid in this situation. Measurements of transepithelial nasal potential differences (NPD) in adults accurately characterize CFTR-related ion transport. The aim of the present study is to establish reference values for NPD measurements for healthy children and those with CF aged 3 months to 3 years, the age range of most difficult-to-diagnose patients with suspected CF. The ultimate goal of our study is to validate NPD testing as a diagnostic tool for children with borderline results in neonatal screening. METHODS/DESIGN: We adapted the standard NPD protocol for young children, designed a special catheter for them, used a slower perfusion rate, and shortened the protocol to include only measurement of basal PD, transepithelial sodium (Na(+)) transport in response to the Na(+ )channel inhibitor amiloride, and CFTR-mediated chloride (Cl(-)) secretion in response to isoproterenol, a β-agonist in a Cl(- )free solution. The study will include 20 children with CF and 20 healthy control children. CF children will be included only if they carry 2 CF-causing mutations in the CFTR gene or have sweat chloride concentrations > 60 mEq/L or both. The healthy children will be recruited among the siblings of the CF patients, after verification that they do not carry the familial mutation. DISCUSSION: A preliminary study of 3 adult control subjects and 4 children older than 12 years with CF verified that the new protocol was well tolerated and produced NPD measurements that did not differ significantly from those obtained with the standard protocol. This preliminary study will provide a basis for interpreting NPD measurements in patients with suspected CF after neonatal screening. Earlier definitive diagnosis should alleviate parental distress and allow earlier therapeutic intervention and genetic counseling

π+\pi^+ photoproduction on the proton for photon energies from 0.725 to 2.875 GeV

Differential cross sections for the reaction $\gamma p \to n \pi^+$ have been measured with the CEBAF Large Acceptance Spectrometer (CLAS) and a tagged photon beam with energies from 0.725 to 2.875 GeV. Where available, the results obtained here compare well with previously published results for the reaction. Agreement with the SAID and MAID analyses is found below 1 GeV. The present set of cross sections has been incorporated into the SAID database, and exploratory fits have been made up to 2.7 GeV. Resonance couplings have been extracted and compared to previous determinations. With the addition of these cross sections to the world data set, significant changes have occurred in the high-energy behavior of the SAID cross-section predictions and amplitudes.Comment: 18 pages, 10 figure