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AbstractUsing learning objectives to guide course design is often considered an educational best practice, but little research exists that explores how students use them over time and across courses. We surveyed students on their use and perceived value of learning objectives as the semester progressed across four science, technology, engineering, and mathematics (STEM) disciplines, examined students’ ability to match exam questions with learning objectives, and analyzed how their course performance related to these qualities. We also gathered instructors’ information on their implementation of learning objectives in these courses. We identified distinct disciplinary differences both in students’ use and perceived benefit of learning objectives and in instructors’ implementation of them. Students in less quantitatively focused courses, i.e., biology and organic chemistry, reported valuing and using learning objectives more than students in more quantitatively focused math and physics courses. Students’ ability to match learning objectives with exam questions, however, positively correlated with exam score and final course grade in all our study courses. Our results have implications for considering disciplinary practices for use of learning objectives as instructors design and implement courses, educational researchers plan studies, and assessment specialists formulate institutional assessment plans.

Metacognition, the ability to think about and regulate one’s thinking, is an important factor in effective student learning. One intervention to promote student metacognition is the exam wrapper—a reflection students complete after an exam noting how their performance related to their preparation. Results are mixed on the effect of the exam wrapper use on student achievement in single STEM courses. In this study, we implemented exam wrappers in five large science and math courses and examined their impact on students’ course outcomes, as well as students’ self-reported behaviors on the Metacognitive Awareness Inventory (results for over 1,100 distinct individuals). Our data include a subset of students who completed exam wrappers in multiple courses simultaneously We observed a modest but statistically significant positive relation between exam wrapper use and course grades in each course. The relation between exam wrapper use in multiple courses and cumulative grade point average was also statistically significant for male students. These results did not correlate with students’ metacognitive awareness, however. These findings have important implications for how instructors construct and implement wrappers to maximize their potential usefulness.

The epimerization of the potassium salts of L-arabinonic, D-ribonic, D-lyxonic and D-xylonic acids in aqueous alkali was followed kinetically by gas Chromatographie analyses of the silylated samples. Mass spectrometric measurements indicated that the reaction proceeded by a complete proton exchange at C2, the kinetic deuterium isotope effect, k-H/k-D being 4.2. Most probably the proton transfer from the C2 atom to hydroxiae ion is the rate-limiting stage of the epimerization.

It was known previously that 1) the relA gene of Escherichia coli encodes an enzyme capable of guanosine 3',5'-bispyrophosphate (ppGpp) synthesis, 2) an uncharacterized source of ppGpp synthesis exists in relA null strains, and 3) cellular degradation of ppGpp is mainly due to a manganese-dependent ppGpp 3'-pyrophosphohydrolase encoded by the spoT gene. Here, the effects of spoT gene insertions and deletions are compared with analogous alterations in neighboring genes in the spo operon and found to be lethal in relA+ strains as well as slower growing in relAl backgrounds than delta relA hosts. Cells with null alleles in both the relA and spoT genes are found no longer to accumulate ppGpp after glucose exhaustion or after chelation of manganese ions by picolinic acid addition; the inability to form ppGpp is reversed by a minimal spoT gene on a multicopy plasmid. Strains apparently lacking ppGpp show a complex phenotype including auxotrophy for several amino acids and morphological alterations. We propose that the SpoT protein can either catalyze or control the alternative pathway of ppGpp synthesis in addition to its known role as a (p)ppGpp 3'-pyrophosphohydrolase. We favor the possibility that the SpoT protein is a bifunctional enzyme capable of catalyzing either ppGpp synthesis or degradation.

The Escherichia coli spoTgene encodes a guanosine-3′,5′-bispyrophosphate (ppGpp) 3′-pyrophosphohydrolase known to be responsible for cellular (ppGpp) degradation. The DNA sequence of the spoTregion is presented. The spoTgene is deduced to be 702 codons long, with a probable UUG initiation codon, and a deduced mass of 79,342 daltons. Two spoTmutations (spoT202and spoT203) have been localized to an open reading frame by complementation of function as well as by genetic marker rescue. The ability to overexpress the spoTgene is limited, but enough ppGppase activity can be made to reverse ppGpp accumulation during the stringent response to amino acid starvation.

Rat cortical synaptosomes were depolarized by the addition of protoveratrine to the incubating medium. The resulting synaptic vesicle aggregation near the synaptic cleft was prevented by vinblastine. Electron microscopy of both routine- and phosphotungstic acid-treated materials suggests the involvement of cytoskeletal structures in stimulation-dependent vesicle redistribution.

Those plastics that have been used by food industry as packaging (especially in sweet industry) have strict requirements. Most of these plastic constructions are primary or secondary packaging with direct or indirect contact with foodstuff. Over the appropriate mechanical properties, these packagings need to be safe enough to be used as direct contact material without any dangerous material migration or transfer. Recently the polyethylene-terephthalate (PET) is that material which is widely used for this kind of purpose and application. To substitute the PET, only that kind of alternative material which are fulfilling the requirements of applications and compliant to the relevant regulations can be applied. The cost-efficient application of plastics strongly depends on the mechanical properties of the material. In light of these facts, both types of polylactic-acid (PDLLA, PLLA) and the PET were tested. Comparing their mechanical properties PLA could be used as a real alternative of PET.

Presents recommendations for preserving identities in stepfamilies. Providing each child and adult a space of their own; Allowing biologically-related family members to spend some time alone during visitations; Sharing with everyone the narratives that define the history of each branch of the family; Remarried couple as the key relationship if a stepfamily is to be a place to live and flourish.