Detailed flow measurements in casing boundary layer of 429-meter-per-second-tip-speed two-stage fan

Detailed flow measurements between all blade rows were taken in the outer 30 percent of passage height of a two stage fan. Tabulations of the detailed flow measurements are included. Results of these measurements revealed the steep axial velocity profiles near the casing. The axial velocity profile near the casing at the rotor exists was much steeper than at the stator exits. The data also show overturning of the flow at the tip at the stator exits. The effect of mixing is shown by the redistribution of the first stage rotor exit total temperature profile as it passes through the following stator

Social Media and Information Overload: Survey Results

A UK-based online questionnaire investigating aspects of usage of user-generated media (UGM), such as Facebook, LinkedIn and Twitter, attracted 587 participants. Results show a high degree of engagement with social networking media such as Facebook, and a significant engagement with other media such as professional media, microblogs and blogs. Participants who experience information overload are those who engage less frequently with the media, rather than those who have fewer posts to read. Professional users show different behaviours to social users. Microbloggers complain of information overload to the greatest extent. Two thirds of Twitter-users have felt that they receive too many posts, and over half of Twitter-users have felt the need for a tool to filter out the irrelevant posts. Generally speaking, participants express satisfaction with the media, though a significant minority express a range of concerns including information overload and privacy

Computer program for aerodynamic and blading design of multistage axial-flow compressors

A code for computing the aerodynamic design of a multistage axial-flow compressor and, if desired, the associated blading geometry input for internal flow analysis codes is presented. Compressible flow, which is assumed to be steady and axisymmetric, is the basis for a two-dimensional solution in the meridional plane with viscous effects modeled by pressure loss coefficients and boundary layer blockage. The radial equation of motion and the continuity equation are solved with the streamline curvature method on calculation stations outside the blade rows. The annulus profile, mass flow, pressure ratio, and rotative speed are input. A number of other input parameters specify and control the blade row aerodynamics and geometry. In particular, blade element centerlines and thicknesses can be specified with fourth degree polynomials for two segments. The output includes a detailed aerodynamic solution and, if desired, blading coordinates that can be used for internal flow analysis codes

The Impact of Social Media on Athletes' Self-Efficacy

The purpose of the study is to understand how social media affects athletes’ self-efficacy. With the ubiquitous presence of social media, it was hypothesized that via social media the source persuasion — one of the four sources that regulates self-efficacy — may be used as a way to encourage or discourage athletes in believing they have, or lack, the skills necessary to complete a task; therefore, persuading athletes to become more or less assured in their abilities despite past experiences. A phenomenological approach was utilized for this study to assist the researcher in conceptualizing ideas that might be dismissed by the boundaries of more traditional approaches. Semi-structured interviews were completed with 10 high-performance athletes in combative sports, and a cross-interview by-question analysis was performed on the data to determine the patterns and themes from the data. Results indicate that social media, and the way that athletes use social media, does have an effect on athletes’ self-efficacy, however the impact of self-efficacy depends on the social media usage

Covid-19 and twitter: abuse towards mps decreased during the lockdown, but that’s only part of the story

Genevieve Gorrell discusses the impact of COVID-19 on the verbal abuse politicians receive on Twitter. She finds that while this kind of abuse appeared to reduce in conjunction with the pandemic, the number of tweets refuting the existence of the virus were numerically significant, as were tweets attacking China

Determination of feline leukemia proviral sequences in naturally infected cats

Felines are susceptible to many different viruses throughout their lifetime, one being Feline Leukemia Virus (FeLV). FeLV is a transmittable RNA retrovirus that inhabits the cells of feline species\u27 immune systems leading to possible infections and diseases such as seizures and other neurological disorders, anemia, stomatitis, enteritis, and lymphoma. There are four different types of this virus, FeLV-A, FeLV-B, FeLV-C, or FeLV-T, that enter cells via different cellular receptors causing different symptoms. FeLV-A is horizontally transmittable, and all FeLV-positive cats carry this form. Of the subtypes, FeLV-B is the most common, being found in approximately 50% of all cases, most often in cats with tumors and other abnormal tissue growths. The aim of this research was to determine the proviral sequences of FeLV-B in multiple tissue samples collected from a FeLV positive cat. Genomic DNA from multiple tissue samples of a naturally infected cat with FeLV-B was extracted and digested with a set of restriction enzymes. Adapters were ligated to known sequences using genome walking and PCR was used to amplify fragments containing proviral FeLV. Samples were sent for sequencing, and the results used to design new primers for further work. It was hypothesized that of the six tissue samples, the tumor samples would show mutations and/or rearrangements not observed in other tissues. FeLV-B was confirmed in five of the six tissue samples extracted. When comparing known FeLV-A and -B sequences, the samples tissues were more closely related to the known FeLV-B. Variations in the tumor samples were observed in the nucleotide sequences and when these variations were altered, mutations within the amino acid sequences were observed

Escherichia coli adenlyosuccinate synthetase: studies on substrate specificity

Enzymes are catalysts of biological reactions, and are characterized by their substrate specificity, specificity of reaction and ability to be regulated. Aspects of enzymes studied are the catalytic mechanisms, association states, origins of substrate specificity, and enzymatic regulation of the enzyme. One enzyme studied as a model system is adenylosuccinate synthetase (E.C. 6.3.4.4, L-aspartate:IMP ligase, GDP forming; AMPSase). Interactions which appear to be important for enzyme association and substrate binding were studied by producing site-directed mutants of AMPSase as guided by the unligated and ligated crystal structures. The wild-type and mutant enzymes were compared by utilizing spectrophotometric assays, to determine their kinetic parameters, circular dichroism, sedimentation equilibrium analytical ultracentrifagation, and matrix-assisted laser desorption ionization. Associative states of the enzyme were studied by generating mutants at positions Arg143, and Asp231. Arg143 forms part of the active site of the opposite monomer, while Asp231 makes interface contacts. The native enzyme is exclusively a dimer in the presence of ligands, though reported as a monomer during purification. There is a direct relationship between dimer formation and activity. Due to intracellular concentrations of AMPSase and ligands, this is postulated to be a method of regulation for the enzyme. The mutations Asp21, Asn38, Thr42 and Arg419 were made to investigate their role in interactions with the 5\u27-phosphoryl group of IMP. The unexpected results yielded insights as to the role of a conformational change of Loop 42 - 53, a dynamic loop in the enzyme. The binding energy for interaction of Asn38 - 5\u27-phosphoryl of IMP goes directly to transition state stabilization, and not towards substrate recognition. Finally, the role of a collection of beta-branched side chains in substrate recognition is examined. Thr128, Thr129 , Thr300 and Thr301 have direct interactions with either L-aspartate or IMP, while Val273 has no bonded contacts with L-aspartate. The effect on the steady-state kinetics by the mutant enzymes reflects the stabilization of the bound complexes by direct hydrogen bonding and conformational limitations on the enzyme for IMP and L-aspartate recognition. The role of the non-bonding contacts is to prevent binding of nonproductive conformations of substrates, as seen by inhibition studies