2,071 research outputs found
A Concept Paper on Networks of Excellence for Research and Education
Research and education ecosystems, foundational components of knowledge-based economies, are relatively underdeveloped in Latin America. The entire ecosystem of a research university — including resources, corporate partnerships, and research — must capitalize on a symbiosis between the research, education and commercialization missions. A university cannot transform unilaterally nor can universities sustain the required transformation without government and industry participation. Initiatives to accelerate the development of research university ecosystems are critical for the realization of knowledge-based economies and resilient civil societies.
To accelerate the development of research and education ecosystems across the Americas, the authors propose to establish “Networks of Excellence” in key focus areas. Each Network of Excellence will be multi-institutional, multi-sector (university, corporate, government, NGO) and multi-national. These multi-faceted networks will allow participants to define and share programs, policies, and content, significantly leverage the resources provided for related programs, and identify opportunities to leapfrog existing programs. Proposed themes for networks include regional grand challenges and cross-cutting capabilities
Associations between Health Effects and Particulate Matter and Black Carbon in Subjects with Respiratory Disease
We measured fractional exhaled nitric oxide (FE(NO)), spirometry, blood pressure, oxygen saturation of the blood (SaO(2)), and pulse rate in 16 older subjects with asthma or chronic obstructive pulmonary disease (COPD) in Seattle, Washington. Data were collected daily for 12 days. We simultaneously collected PM(10) and PM(2.5) (particulate matter ≤10 μm or ≤2.5 μm, respectively) filter samples at a central outdoor site, as well as outside and inside the subjects’ homes. Personal PM(10) filter samples were also collected. All filters were analyzed for mass and light absorbance. We analyzed within-subject associations between health outcomes and air pollution metrics using a linear mixed-effects model with random intercept, controlling for age, ambient relative humidity, and ambient temperature. For the 7 subjects with asthma, a 10 μg/m(3) increase in 24-hr average outdoor PM(10) and PM(2.5) was associated with a 5.9 [95% confidence interval (CI), 2.9–8.9] and 4.2 ppb (95% CI, 1.3–7.1) increase in FE(NO), respectively. A 1 μg/m(3) increase in outdoor, indoor, and personal black carbon (BC) was associated with increases in FE(NO) of 2.3 ppb (95% CI, 1.1–3.6), 4.0 ppb (95% CI, 2.0–5.9), and 1.2 ppb (95% CI, 0.2–2.2), respectively. No significant association was found between PM or BC measures and changes in spirometry, blood pressure, pulse rate, or SaO(2) in these subjects. Results from this study indicate that FE(NO) may be a more sensitive marker of PM exposure than traditional health outcomes and that particle-associated BC is useful for examining associations between primary combustion constituents of PM and health outcomes
Theoretical current-voltage characteristics of ferroelectric tunnel junctions
We present the concept of ferroelectric tunnel junctions (FTJs). These
junctions consist of two metal electrodes separated by a nanometer-thick
ferroelectric barrier. The current-voltage characteristics of FTJs are analyzed
under the assumption that the direct electron tunneling represents the dominant
conduction mechanism. First, the influence of converse piezoelectric effect
inherent in ferroelectric materials on the tunnel current is described. The
calculations show that the lattice strains of piezoelectric origin modify the
current-voltage relationship owing to strain-induced changes of the barrier
thickness, electron effective mass, and position of the conduction-band edge.
Remarkably, the conductance minimum becomes shifted from zero voltage due to
the piezoelectric effect, and a strain-related resistive switching takes place
after the polarization reversal in a ferroelectric barrier. Second, we analyze
the influence of the internal electric field arising due to imperfect screening
of polarization charges by electrons in metal electrodes. It is shown that, for
asymmetric FTJs, this depolarizing-field effect also leads to a considerable
change of the barrier resistance after the polarization reversal. However, the
symmetry of the resulting current-voltage loop is different from that
characteristic of the strain-related resistive switching. The crossover from
one to another type of the hysteretic curve, which accompanies the increase of
FTJ asymmetry, is described taking into account both the strain and
depolarizing-field effects. It is noted that asymmetric FTJs with dissimilar
top and bottom electrodes are preferable for the non-volatile memory
applications because of a larger resistance on/off ratio.Comment: 14 pages, 8 figure
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Tracking ultrafast non-adiabatic dissociation dynamics of the deuterated water dication molecule
We applied reaction microscopy to elucidate fast non-adiabatic dissociation dynamics of deuterated water molecules after direct photo-double ionization at 61 eV with synchrotron radiation. For the very rare D+ + O+ + D breakup channel, the particle momenta, angular, and energy distributions of electrons and ions, measured in coincidence, reveal distinct electronic dication states and their dissociation pathways via spin-orbit coupling and charge transfer at crossings and seams on the potential energy surfaces. Notably, we could distinguish between direct and fast sequential dissociation scenarios. For the latter case, our measurements reveal the geometry and orientation of the deuterated water molecule with respect to the polarization vector that leads to this rare 3-body molecular breakup channel. Aided by multi-reference configuration-interaction calculations, the dissociation dynamics could be traced on the relevant potential energy surfaces and particularly their crossings and seams. This approach also unraveled the ultrafast time scales governing these processes
Precarious, Always-On and Flexible: A Case Study of Academics as Information Workers
The higher education landscape has changed in the last decades. The neoliberal restructuring of universities has led to transformations such as reducing public expenditure, allocating resources based on competition and quasi-market disciplines. These structural transformations have also an effect on the working conditions, practices and relations of subjects within universities. Questions that need to be addressed: How do different working contexts and conditions in the academia shape feelings of autonomy, flexibility and reputation on the one hand and precariousness, overwork and dissatisfaction on the other? What are the broader political realities and potentials in terms of solidarity, participation and democracy at universities? I address these questions based on a theoretical analysis and qualitative interviews with precariously employed academics
Antiproton Production in 11.5 A GeV/c Au+Pb Nucleus-Nucleus Collisions
We present the first results from the E864 collaboration on the production of
antiprotons in 10% central 11.5 A GeV/c Au+Pb nucleus collisions at the
Brookhaven AGS. We report invariant multiplicities for antiproton production in
the kinematic region 1.4<y<2.2 and 50<p_T<300 MeV/c, and compare our data with
a first collision scaling model and previously published results from the E878
collaboration. The differences between the E864 and E878 antiproton
measurements and the implications for antihyperon production are discussed.Comment: 4 pages, 4 figures; accepted for publication in Physical Review
Letter
Electron scattering from molecules and molecular aggregates of biological relevance
In this Topical Review we survey the current state of the art in the study of low energy electron collisions with biologically relevant molecules and molecular clusters. We briefly describe the methods and techniques used in the investigation of these processes and summarise the results obtained so far for DNA constituents and their model compounds, amino acids, peptides and other biomolecules. The applications of the data obtained is briefly described as well as future required developments
Mass dependence of light nucleus production in ultrarelativistic heavy ion collisions
Light nuclei can be produced in the central reaction zone via coalescence in
relativistic heavy ion collisions. E864 at BNL has measured the production of
ten light nuclei with nuclear number of A=1 to A=7 at rapidity and
. Data were taken with a Au beam of momentum of 11.5 A
on a Pb or Pt target with different experimental settings. The
invariant yields show a striking exponential dependence on nuclear number with
a penalty factor of about 50 per additional nucleon. Detailed analysis reveals
that the production may depend on the spin factor of the nucleus and the
nuclear binding energy as well.Comment: (6 pages, 3 figures), some changes on text, references and figures'
lettering. To be published in PRL (13Dec1999
Direct measurement of the pion valence quark momentum distribution, the pion light-cone wave function squared
We present the first direct measurements of the pion valence quark momentum
distribution which is related to the square of the pion light-cone wave
function. The measurements were carried out using data on diffractive
dissociation of 500 GeV/c into di-jets from a platinum target at
Fermilab experiment E791. The results show that the light-cone
asymptotic wave function, which was developed using perturbative QCD methods,
describes the data well for or more. We also
measured the transverse momentum distribution of the diffractive di-jets.Comment: 13 pages, 4 figure
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