Limiting Student Speech: A Narrow Path Toward Success. A Response to Challenging the Common Guidelines in Social Justice Education

In this response, Minnick asserts that unequal representation of students\u27 voices, an idea presented in Sensoy and DiAngelo’s “Challenging the Common Guidelines in Social Justice Education,” presents multiple negative classroom implications. Foremost, Minnick argues that Sensoy and DiAngelo’s lack of clarity regarding when a teacher should limit student speech (either before the student begins to talk or midcomment) has a large effect on the success of their strategy. Second, Sensoy and DiAngelo’s discussion strategy may result in the targeting of minority students and the judging of students. These concerns are driven by considerations of how teachers’ relationships with students influence their ability to effectively limit and enable student speech

Differential expression of the invasion-associated locus B (ialB) gene of Bartonella bacilliformis in response to environmental cues

Bartonella bacilliformis is the causative agent of the biphasic human disease, Oroya fever. During the primary disease phase, up to 100% of the circulating erythrocytes can be parasitized and 80% lysed. During the secondary phase of this disease, bacterial invasion shifts to endothelial cells lining the vasculature. B. bacilliformis is transferred between human hosts by the sandfly, Lutzomyia verrucarum. To investigate the regulation of ialB by environmental cues signaling vector-to-host transmission; nuclease protection assays were performed to compare the amount of ialB mRNA in bacteria subjected to temperature shift, pH change, oxidative stress, or hemin limitation. The amount of ialB mRNA increased by 223-310% in acid-treated samples and decreased by 28-39% in base-treated samples as compared to bacteria kept at pH 7.2. B. bacilliformis samples showed a 56-63% and 74-80% decrease in ialB mRNA when shifted to 37 degrees C from growth temperatures of 20 and 30 degrees C, respectively. Oxidative stress (1 mM H(2)O(2)) and hemin limitation had no significant effect on mRNA levels. Determination of IalB protein amounts using SDS-PAGE and immunoblotting showed the greatest amounts of IalB under acidic conditions or at 20 degrees C. The least amount of IalB was synthesized under basic conditions or at 37 degrees C. The viability of wild-type B. bacilliformis under the various experimental culture conditions was determined and found not to affect ialB mRNA amounts in these experiments. Finally, we compared the survival of wild-type and ialB mutant B. bacilliformis and found no difference in the viability of these two strains, demonstrating that IalB does not aid bacterial survival under these conditions

Cryogenic Vacuum Insulation for Vessels and Piping

Cryogenic vacuum insulation systems, with proper materials selection and execution, can offer the highest levels of thermal performance. Three areas of consideration are vital to achieve the optimum result: materials, representative test conditions, and engineering approach for the particular application. Deficiency in one of these three areas can prevent optimum performance and lead to severe inefficiency. Materials of interest include micro-fiberglass, multilayer insulation, and composite arrangements. Cylindrical liquid nitrogen boil-off calorimetry methods were used. The need for standard thermal conductivity data is addressed through baseline testing. Engineering analysis and design factors such as layer thickness, density, and practicality are also considered

Unipolar arcing on the cathode surface of a high voltage diode.

http://archive.org/details/unipolararcingon00minnN

Model reference control of distributed parameter systems: Application to the SCOLE problem

The model reference control of lumped linear systems and the model reference control of the distributed parameter system (DPS) are presented with their theory and Spacecraft Control Laboratory Experiment (SCOLE) applications

Characterization and expression of the cbbE\u27 gene of Coxiella burnetii

A gene which is unique to the QpRS plasmid from chronic isolates of Coxiella burnetii was cloned, sequenced, and expressed in Escherichia coli. This gene, termed cbbE\u27, codes for a putative surface protein of approximately 55 kDa, termed the E\u27 protein. The cbbE\u27 gene is 1485 bp in length, and is preceded by predicted promoter regulatory sequences of TTTAAT (-35), TATAAT (-10), and a Shine-Dalgarno sequence of GGAGAGA, all of which closely resemble those of E. coli and other rickettsiae. The open reading frame (ORF) of cbbE\u27 ends with a UAA codon followed by a second in-frame UAG stop codon and a region of dyad symmetry which may act as a rho-factor-independent terminator. The ORF of cbbE\u27 is capable of coding for a polypeptide of 495 amino acids with a predicted molecular mass of 55893 Da. The E\u27 protein has a predicted pI of approximately 8.7, and contains a distinct hydrophobic region of 12 amino acid residues. In vitro transcription/translation and E. coli expression of recombinant plasmids containing cbbE\u27 produce a protein of approximately 55 kDa. The in vivo expression of cbbE\u27 yields a novel protein that can be detected on immunoblots developed with rabbit antiserum generated against purified outer membrane from C. burnetii. DNA hybridization analysis shows that cbbE\u27 is unique to the QpRS plasmid found in chronic isolates of C. burnetii, and is absent in chromosomal DNA and plasmids (QpH1, QpDG) from other isolates of C. burnetii. A search of various DNA and amino acid sequence data bases revealed no homologies to cbbE\u27

Status of flexible CIS research at ISET

Polycrystalline thin film solar cells fabricated on light-weight, flexible substrates are very attractive for space applications. In this work CulnSe2 (CIS) based thin film devices were processed on metallic foil substrates using the selenization technique. CIS deposition method involved reaction of electron-bean evaporated Cu-In precursor layers with a selenizing atmosphere at around 400 C. Several metallic foils such as Mo, Ti, Al, Ni, and Cu were evaluated as possible substrates for these devices. Solar cells with AM1.5 efficiencies of 9.0-9.34 percent and good mechanical integrity were demonstrated on Mo and Ti foils. Monolithic integration of these devices was also demonstrated up to 4 in x 4 in size

New Measurement of the Cosmic-Ray Positron Fraction from 5 to 15 GeV

We present a new measurement of the cosmic-ray positron fraction at energies between 5 and 15 GeV with the balloon-borne HEAT-pbar instrument in the spring of 2000. The data presented here are compatible with our previous measurements, obtained with a different instrument. The combined data from the three HEAT flights indicate a small positron flux of non-standard origin above 5 GeV. We compare the new measurement with earlier data obtained with the HEAT-e+- instrument, during the opposite epoch of the solar cycle, and conclude that our measurements do not support predictions of charge sign dependent solar modulation of the positron abundance at 5 GeV.Comment: accepted for publication in PR

Characterization and expression analysis of the groESL operon of Bartonella bacilliformis

The groESL operon of Bartonella bacilliformis, a facultative intracellular, Gram-negative bacterium and etiologic agent of Oroya Fever, was characterized. Sequence analysis revealed an operon containing two genes of 294 (groES) and 1632 nucleotides (groEL) separated by a 55-nt intergenic spacer. The operon is preceded by a 72-nt ORF (ORF1) that encodes a hypothetical protein with homology to a portion of the HrcA repressor for groESL. A divergent fumarate hydratase C (fumC) gene lies further upstream. Deduced amino acid sequences for B. bacilliformis GroEL and GroES revealed a high degree of identity with homologues from other Bartonella and alpha-Protebacteria. A single transcriptional start site (TSS) was mapped 79 nucleotides upstream of the groES start codon, regardless of incubation temperature. The TSS was located immediately 5\u27 to a potential controlling inverted repeat of chaperonin expression (CIRCE) element and is preceded by a sigma70-like promoter. The operon is followed by a predicted rho-independent transcriptional terminator. Northern blot analysis indicated that groES and groEL are co-transcribed as a single mRNA of approximately 2.4 kb. A 6-h time course analysis by qRT-PCR showed that groEL expression increases 1.3-fold within 30 min of a temperature upshift from 30 to 37 degrees C, with maximum transcription reached after 60 min (approximately 4.3-fold), followed by a steady decrease to background (30 degrees C) transcription levels by 6 h. Western blot analysis revealed a 1.4- and 1.5-fold increase in GroEL synthesis following a temperature upshift or by inhibiting DNA supercoiling with coumermycin A1, respectively. Functional expression and complementation of temperature-sensitive Escherichia coli groES or groEL mutants with the cloned operon allowed them to grow at otherwise restrictive temperatures

Analysis of the Caenorhabditis elegans innate immune response to Coxiella burnetii

The nematode Caenorhabditis elegans is well established as a system for characterization and discovery of molecular mechanisms mediating microbe-specific inducible innate immune responses to human pathogens. Coxiella burnetii is an obligate intracellular bacterium that causes a flu-like syndrome in humans (Q fever), as well as abortions in domesticated livestock, worldwide. Initially, when wild type C. elegans (N2 strain) was exposed to mCherry-expressing C. burnetii (CCB) a number of overt pathological manifestations resulted, including intestinal distension, deformed anal region and a decreased lifespan. However, nematodes fed autoclave-killed CCB did not exhibit these symptoms. Although vertebrates detect C. burnetii via TLRs, pathologies in tol-1(-) mutant nematodes were indistinguishable from N2, and indicate nematodes do not employ this orthologue for detection of C. burnetii. sek-1(-) MAP kinase mutant nematodes succumbed to infection faster, suggesting that this signaling pathway plays a role in immune activation, as previously shown for orthologues in vertebrates during a C. burnetii infection. C. elegans daf-2(-) mutants are hyper-immune and exhibited significantly reduced pathological consequences during challenge. Collectively, these results demonstrate the utility of C. elegans for studying the innate immune response against C. burnetii and could lead to discovery of novel methods for prevention and treatment of disease in humans and livestock