Lunar soil engineering and engineering geology, July 1-31, 1967

Lunar soil and rock program in support of lunar exploratio

Multimedia interactive eBooks in laboratory science education

Bioscience students in the UK higher education system are making increasing use of technology to support their learning within taught classes and during private study. This experimental study was designed to assess the role for multimedia interactive eBooks in bioscience laboratory classes, delivered using a blended learning approach. Thirty-nine second-year students on a Biomedical Science undergraduate course in a UK university were grouped using an experimental design into alternating trial and control groups and provided with pre-configured iPad tablet devices containing multimedia interactive eBooks. Data collection involved weekly surveys including quantitative and qualitative responses, and analysis of summative assessment marks. Analysis of the results using descriptive statistics methods showed that students made extensive use of eBooks in practical classes and over 70% of students agreed that the eBooks were beneficial for learning. However, less than 40% of students indicated a preference for eBooks over traditional paper protocols for practical-based classes. Although the eBooks were well used by students, they had no statistically significant effect on assessment marks. Overall, the study highlighted the positive feedback from students relating to multimedia interactive eBooks for supporting students’ learning, but illustrated that there are other factors affecting adoption of new technologies

Inelastic tunneling characteristics of AIAs/GaAs heterojunction barriers

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Elastic and inelastic tunneling characteristics of AIAs/GaAs heterojunctions

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Serre Theorem for involutory Hopf algebras

We call a monoidal category ${\mathcal C}$ a Serre category if for any $C$, $D \in {\mathcal C}$ such that C\ot D is semisimple, $C$ and $D$ are semisimple objects in ${\mathcal C}$. Let $H$ be an involutory Hopf algebra, $M$, $N$ two $H$-(co)modules such that $M \otimes N$ is (co)semisimple as a $H$-(co)module. If $N$ (resp. $M$) is a finitely generated projective $k$-module with invertible Hattory-Stallings rank in $k$ then $M$ (resp. $N$) is (co)semisimple as a $H$-(co)module. In particular, the full subcategory of all finite dimensional modules, comodules or Yetter-Drinfel'd modules over $H$ the dimension of which is invertible in $k$ are Serre categories.Comment: a new version: 8 page

Thin-film chemical sensors based on electron tunneling

The physical mechanisms underlying a novel chemical sensor based on electron tunneling in metal-insulator-metal (MIM) tunnel junctions were studied. Chemical sensors based on electron tunneling were shown to be sensitive to a variety of substances that include iodine, mercury, bismuth, ethylenedibromide, and ethylenedichloride. A sensitivity of 13 parts per billion of iodine dissolved in hexane was demonstrated. The physical mechanisms involved in the chemical sensitivity of these devices were determined to be the chemical alteration of the surface electronic structure of the top metal electrode in the MIM structure. In addition, electroreflectance spectroscopy (ERS) was studied as a complementary surface-sensitive technique. ERS was shown to be sensitive to both iodine and mercury. Electrolyte electroreflectance and solid-state MIM electroreflectance revealed qualitatively the same chemical response. A modified thin-film structure was also studied in which a chemically active layer was introduced at the top Metal-Insulator interface of the MIM devices. Cobalt phthalocyanine was used for the chemically active layer in this study. Devices modified in this way were shown to be sensitive to iodine and nitrogen dioxide. The chemical sensitivity of the modified structure was due to conductance changes in the active layer

Placental weight and mortality in premenopausal breast cancer by tumor characteristics

Placental weight may be regarded as an indirect marker of hormone exposures during pregnancy. There is epidemiological evidence that breast cancer mortality in premenopausal women increases with placental weight in the most recent pregnancy. We investigated if this association differs by tumor characteristics, including expression of estrogen and progesterone receptors. In a Swedish population-based cohort, we followed 1,067 women with premenopausal breast cancer diagnosed from 1992 to 2006. Using Cox regression models, we estimated hazard ratios for the association between placental weight and risk of premenopausal breast cancer mortality. In stratified analyses, we estimated mortality risks in subjects with different tumor stages, estrogen receptor (ER) or progesterone receptor (PR) status. Compared with women with placental weight less than 600 g, women with a placental weight between 600 and 699 g were at a 50 % increased risk of mortality, however, not significant change in risk was observed for women with placental weight �700 g. Mortality risks associated with higher placental weight were more pronounced among ER- and PR- breast cancer tumors, where both a placental weight 600-699 g and �700 g were associated with a more than doubled mortality risks compared with tumors among women with placental weight less than 600 g. Moreover, stratified analyses for joint receptor status revealed that a consistent increased mortality risk by placental weight was only apparent in women with ER-/PR- breast cancer. The increased mortality risk in premenopausal breast cancer associated with higher placental weight was most pronounced among ER- and PR- tumors. © 2012 Springer Science+Business Media New York

A New Disease in Iowa Corn Fields

It resembles maize dwarf mosaic found in Ohio, Symptoms vary widely and may include red or purple streaking of leaves or severe stunting. Research is underway and is being intensified

Comparison maps for relatively free resolutions

Let Λ be a commutative ring, A an augmented differential graded algebra over Λ (briefly, DGA-algebra) and X be a relatively free resolution of Λ over A. The standard bar resolution of Λ over A, denoted by B(A), provides an example of a resolution of this kind. The comparison theorem gives inductive formulae f : B(A)→X and g : X→B(A) termed comparison maps. In case that fg=1 X and A is connected, we show that X is endowed a A  ∞ -tensor product structure. In case that A is in addition commutative then (X,μ X ) is shown to be a commutative DGA-algebra with the product μ X =f*(g⊗g) (* is the shuffle product in B(A)). Furthermore, f and g are algebra maps. We give an example in order to illustrate the main results of this paper