Tunneling spectroscopy studies of aluminum oxide tunnel barrier layers

We report scanning tunneling microscopy and ballistic electron emission microscopy studies of the electronic states of the uncovered and chemisorbed-oxygen covered surface of AlOx tunnel barrier layers. These states change when chemisorbed oxygen ions are moved into the oxide by either flood gun electron bombardment or by thermal annealing. The former, if sufficiently energetic, results in locally well defined conduction band onsets at ~1 V, while the latter results in a progressively higher local conduction band onset, exceeding 2.3 V for 500 and 600 C thermal anneals

The 2007 Provincial Election and Electoral System Referendum in Ontario

Ontario’s general election in Oct. 10, 2007, was unprecedented for several reasons. The election was held on a date fixed by legislation and not one set by the premier or his caucus, something new to Ontario and relatively new to Canadian politics. Turnout declined to 53%, the lowest ever in Ontario history. The incumbent Liberals won a second consecutive majority government, something the party had not achieved since 1937. And finally, the election featured a referendum question that asked voters in Ontario to approve reforms to the electoral system, a proposal that was overwhelmingly rejected. This article explores each of the above-stated elements as they unfolded in the election

Fosamprenavir treatment in a highly active antiretroviral therapy schedule induces a HCV-RNA decrease and a Th1 network boost in HIV/HCV-coinfected patients

AbstractHIV/HCV co-infected naïve patients (four females and six males) were evaluated for their response to the following treatment schedule: [(AZT 300 mg + 3TC 300 mg twice daily) + (fosamprenavir 700 mg twice daily) + (RTV 100 mg)]. CD3+/CD4+ T cells, interferon-γ (INF-γ) and interleukin-4 (IL-4) HCV-specific response, viral loads and transaminase levels were evaluated at time 0, and after 1, 3 and 6 months of therapy (T0, T1, T3, and T6 respectively). HIV-RNA, HCV-RNA and transaminases decreased at T1 and T3 compared with T0 (Mann–Whitney p <0.001, p <0.01 and p <0.01, respectively). At all time points, CD4+ and HCV-specific INF-γ responses were higher (p <0.001; p <0.001), and IL-4 lower (p <0.01) after treatment. At T6, HCV-RNA was only negative in four out of ten patients whereas all had normal transaminase levels. These findings indicate that HAART treatment including fosamprenavir is able to activate a Th1 network in HIV/HCV co-infected patients. Moreover, these results, to be confirmed by larger cohort follow-up studies, suggest that this protease inhibitor could have potential implications for the treatment of chronic hepatitis C in HIV–positive patients

Crack propagation calculations in aircraft engines by coupled FEM-DBEM approach

New generation jet engines are subject to severe reduced fuel consumption requirements. This usually leads to thin components in which damage issues such as thermomechanical fatigue, creep and crack propagation can be quite important. The combination of stresses due to centrifugal loads and thermal stresses usually leads to mixed-mode loading. Consequently, a suitable crack propagation tool must be able to predict mixed-mode crack propagation of arbitrarily curved cracks in three-dimensional space. To tackle this problem a procedure has been developed based on a combined FEM (Finite Element Method) - DBEM (Dual Boundary Element Method) approach. Starting from a three-dimensional FEM mesh for the uncracked structure a subdomain is identified, in which crack initiation and propagation are simulated by DBEM. Such subdomain is extracted from the FEM domain and imported, together with its boundary conditions (calculated by a previous thermal-stress FEM analysis), in a DBEM environment, where a linear elastic crack growth calculation is performed. Once the crack propagation direction is determined a new crack increment can be calculated and for the new crack front the procedure can be repeated until failure. The proposed procedure allows to also consider the spectrum effects and the creep effects: both conditions relieve residual stresses that the crack encounters during its propagation. The procedure has been tested on a gas turbine vane, getting sound results, and can be made fully automatic, thanks to in house made routines needed to facilitate the data exchange between the two adopted codes

Between Culture and Curricula: Exploring Student and Faculty Experiences of Undergraduate Research and Inquiry

Undergraduate research and inquiry is a growing movement within the teaching and learning nexus, with many institutions developing their practices within this culture of education. This study aimed to identify the perceptions and experiences surrounding undergraduate research and inquiry among students and faculty at McMaster University in Ontario, Canada; assess the extent of research and inquiry in the design of undergraduate courses; and explore the facilitators and obstacles educators encounter when attempting to implement this educational approach. Although differences exist in student and faculty definitions of undergraduate research and inquiry, we found two principal models that characterize its structure and delivery—the scaffold model and bookend model. A third, the abstract model, does not employ the practice of inquiry. Despite numerous benefits unique to undergraduate research and inquiry education identified by stakeholders, notable barriers (such as funding, faculty buy-in, limited student experience, and inherent competition) hinder its progress. Overall, we found a diversity of undergraduate research and inquiry practices across the university, operating within varying cultures and comfort levels, which suggests unequal access for student learners

Phase-sensitive imaging of cold atoms at the shot-noise limit

Extent: 5p.We demonstrate simultaneous phase and amplitude imaging of cold atoms using an intrinsically stable interferometer based on polarization beam-displacers. This method allows for the straight-forward retrieval of absorption and phase-shift experienced by an optical probe transmitted through an atomic sample. Furthermore, we show that our technique has a signal-to-noise ratio limited only by photon shot-noise. © 2013 AIP Publishing LLC.P. S. Light, C. Perrella, and A. N. Luite

Morphological, Gene, and Hormonal Changes in Gonads and In-Creased Micrococcal Nuclease Accessibility of Sperm Chromatin Induced by Mercury

Mercury is one of the most dangerous environmental pollutants. In this work, we analysed the effects of exposure of Mytilus galloprovincialis to 1, 10 and 100 pM HgCl2 for 24 h on the gonadal morphology and on the expression level of three stress genes: mt10, hsp70 and πgst. In this tissue we also evaluated the level of steroidogenic enzymes 3β-HSD and 17β-HSD and the expression of PL protein genes. Finally, we determined difference in sperm chromatin accessibility to micrococcal nuclease. We found alterations in gonadal morphology especially after exposure to 10 and 100 pM HgCl2 and hypo-expression of the three stress genes, particularly for hsp70. Furthermore, decreased labelling with both 3β-HSD and 17β-HSD antibodies was observed following exposure to 1 and 10 pM HgCl2 and complete absence at 100 pM HgCl2 exposure. Gonads of mussels exposed to all HgCl2 doses showed decreased expression of PL protein genes especially for PLIII. Finally, micrococcal nuclease digestions showed that all doses of HgCl2 exposure resulted in increased sperm chromatin accessibility to this enzyme, indicative of improper sperm chromatin structure. All of these changes provide preliminary data of the potential toxicity of mercury on the reproductive health of this mussel

Objective Knowledge Mediates the Relationship between the Use of Social Media and COVID-19-Related False Memories

The exposure to relevant social and/or historical events can increase the generation of false memories (FMs). The Coronavirus Disease 2019 (COVID-19) pandemic is a calamity challenging health, political, and journalistic bodies, with media generating confusion that has facilitated the spread of fake news. In this respect, our study aims at investigating the relationships between memories (true memories, TMs vs. FMs) for COVID-19-related news and different individual variables (i.e., use of traditional and social media, COVID-19 perceived and objective knowledge, fear of the disease, depression and anxiety symptoms, reasoning skills, and coping mechanisms). One hundred and seventy-one university students (131 females) were surveyed. Overall, our results suggested that depression and anxiety symptoms, reasoning skills, and coping mechanisms did not affect the formation of FMs. Conversely, the fear of loved ones contracting the infection was found to be negatively associated with FMs. This finding might be due to an empathy/prosociality-based positive bias boosting memory abilities, also explained by the young age of participants. Furthermore, objective knowledge (i) predicted an increase in TMs and decrease in FMs and (ii) significantly mediated the relationships between the use of social media and development of both TMs and FMs. In particular, higher levels of objective knowledge strengthened the formation of TMs and decreased the development of FMs following use of social media. These results may lead to reconsidering the idea of social media as the main source of fake news. This claim is further supported by either the lack of substantial differences between the use of traditional and social media among participants reporting FMs or the positive association between use of social media and levels of objective knowledge. The knowledge about the topic rather than the type of source would make a difference in the process of memory formation

High-efficiency cross-phase modulation in a gas-filled waveguide

Strong cross-Kerr nonlinearities have been long sought after for quantum information applications. Recent work has shown that they are intrinsically unreliable in traveling-wave configurations: cavity configurations avoid this, but require knowledge of both the nonlinearity and the loss. Here we present a detailed systematic study of cross-phase modulation and absorption in an Rb vapor confined within a hollow-core photonic crystal fiber. Using a two-photon transition, we observe phase modulations of up to pi rad with a signal power of 25 mu W, corresponding to a nonlinear Kerr coefficient, n(2), of 0.8 x 10(-6) cm(2)/W, or 1.3 x 10(-6) rad per photon