Quantum transport efficiency and Fourier's law

We analyze the steady-state energy transfer in a chain of coupled two-level systems connecting two thermal reservoirs. Through an analytic treatment we find that the energy current is independent of the system size, hence violating Fourier's law of heat conduction. The classical diffusive behavior in Fourier's law of heat conduction can be recovered by introducing decoherence to the quantum systems constituting the chain. Implications of these results on energy transfer in biological light harvesting systems, and the role of quantum coherences and entanglement are discussed.Comment: 6 pages, 4 figure

Duality and Pro-Spectra

Cofiltered diagrams of spectra, also called pro-spectra, have arisen in diverse areas, and to date have been treated in an ad hoc manner. The purpose of this paper is to systematically develop a homotopy theory of pro-spectra and to study its relation to the usual homotopy theory of spectra, as a foundation for future applications. The surprising result we find is that our homotopy theory of pro-spectra is Quillen equivalent to the opposite of the homotopy theory of spectra. This provides a convenient duality theory for all spectra, extending the classical notion of Spanier-Whitehead duality which works well only for finite spectra. Roughly speaking, the new duality functor takes a spectrum to the cofiltered diagram of the Spanier-Whitehead duals of its finite subcomplexes. In the other direction, the duality functor takes a cofiltered diagram of spectra to the filtered colimit of the Spanier-Whitehead duals of the spectra in the diagram. We prove the equivalence of homotopy theories by showing that both are equivalent to the category of ind-spectra (filtered diagrams of spectra). To construct our new homotopy theories, we prove a general existence theorem for colocalization model structures generalizing known results for cofibrantly generated model categories.Comment: Published by Algebraic and Geometric Topology at http://www.maths.warwick.ac.uk/agt/AGTVol4/agt-4-34.abs.htm

Quantized time correlation function approach to non-adiabatic decay rates in condensed phase: Application to solvated electrons in water and methanol

A new, alternative form of the golden rule formula defining the non-adiabatic transition rate between two quantum states in condensed phase is presented. The formula involves the quantum time correlation function of the energy gap, of the non-adiabatic coupling, and their cross terms. Those quantities can be inferred from their classical counterparts, determined via MD simulations. The formalism is applied to the problem of the non-adiabatic relaxation of an equilibrated p-electron in water and methanol. We find that, in both solvent, the relaxation is induced by the coupling to the vibrational modes and the quantum effects modify the rate by a factor of 2-10 depending on the quantization procedure applied. The resulting p-state lifetime for a hypothetical equilibrium excited state appears extremely short, in the sub-100 fs regime. Although this result is in contrast with all previous theoretical predictions, we also illustrate that the lifetimes computed here are very sensitive to the simulated electronic quantum gap and to the strongly correlated non-adiabatic coupling

Aqueous-Phase Reactive Uptake of Dicarbonyls as a Source of Organic Aerosol Over Eastern North America

We use a global 3-D atmospheric chemistry model (GEOS-Chem) to simulate surface and aircraft measurements of organic carbon (OC) aerosol over eastern North America during summer 2004 (ICARTT aircraft campaign), with the goal of evaluating the potential importance of a new secondary organic aerosol (SOA) formation pathway via irreversible uptake of dicarbonyl gases (glyoxal and methylglyoxal) by aqueous particles. Both dicarbonyls are predominantly produced in the atmosphere by isoprene, with minor contributions from other biogenic and anthropogenic precursors. Dicarbonyl SOA formation is represented by a reactive uptake coefficient γ = 2.9 × 10−3 and takes place mainly in clouds. Surface measurements of OC aerosol at the IMPROVE network in the eastern U.S. average 2.2 ± 0.7 μg C m−3 for July–August 2004 with little regional structure. The corresponding model concentration is 2.8 ± 0.8 μg C m−3, also with little regional structure due to compensating spatial patterns of biogenic, anthropogenic, and fire contributions. Aircraft measurements of water-soluble organic carbon (WSOC) aerosol average 2.2 ± 1.2 μg C m−3 in the boundary layer (<2 km) and 0.9 ± 0.8 μg C m−3 in the free troposphere (2–6 km), consistent with the model (2.0 ± 1.2 μg C m−3 in the boundary layer and 1.1 ± 1.0 μg C m−3 in the free troposphere). Source attribution for the WSOC aerosol in the model boundary layer is 27% anthropogenic, 18% fire, 28% semi-volatile SOA, and 27% dicarbonyl SOA. In the free troposphere it is 13% anthropogenic, 37% fire, 23% semi-volatile SOA, and 27% dicarbonyl SOA. Inclusion of dicarbonyl SOA doubles the SOA contribution to WSOC aerosol at all altitudes. Observed and simulated correlations of WSOC aerosol with other chemical variables measured aboard the aircraft suggest a major SOA source in the free troposphere compatible with the dicarbonyl mechanism.Earth and Planetary SciencesEngineering and Applied Science

Quasiparticle spectrum of d-wave superconductors in the mixed state: a large Fermi-velocity anisotropy study

The quasiparticle spectrum of a two-dimensional d-wave superconductor in the mixed state, H_c1 << H << H_c2, is studied for large values of the ``anisotropy ratio'' alpha_D = v_F/v_Delta. For a square vortex lattice rotated by 45 degrees from the quasiparticle anisotropy axes (and the usual choice of Franz--Tesanovic singular gauge transformation) we determine essential features of the band structure asymptotically for large alpha_D, using an effective one-dimensional model, and compare them to numerical calculations. We find that several features of the band structure decay to zero exponentially fast for large alpha_D. Using a different choice of singular gauge transformation, we obtain a different band structure, but still find qualitative agreement between the 1D and full 2D calculations. Finally, we distort the square lattice into a non-Bravais lattice. Both the one- and two-dimensional numerical calculations of the energy spectra show a gap around zero-energy, with our gauge choice, and the two excitation spectra agree reasonably well.Comment: 14 pages, 13 figures, revte

Painful losses

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134073/1/jhm2610-sup-0001-suppinfo.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134073/2/jhm2610.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134073/3/jhm2610-sup-0002-suppinfo.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134073/4/jhm2610-sup-0005-suppinfo.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134073/5/jhm2610-sup-0003-suppinfo.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134073/6/jhm2610-sup-0004-suppinfo.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134073/7/jhm2610_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134073/8/jhm2610-sup-0007-suppinfo.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134073/9/jhm2610-sup-0006-suppinfo.pd

Global Budgets of Atmospheric Glyoxal and Methylglyoxal, and Implications for Formation of Secondary Organic Aerosols

We construct global budgets of atmospheric glyoxal and methylglyoxal with the goal of quantifying their potential for global secondary organic aerosol (SOA) formation via irreversible uptake by aqueous aerosols and clouds. We conduct a detailed simulation of glyoxal and methylglyoxal in the GEOS-Chem global 3-D chemical transport model including our best knowledge of source and sink processes. Our resulting best estimates of the global sources of glyoxal and methylglyoxal are 45 Tg a−1 and 140 Tg a−1, respectively. Oxidation of biogenic isoprene contributes globally 47% of glyoxal and 79% of methylglyoxal. The second most important precursors are acetylene (mostly anthropogenic) for glyoxal and acetone (mostly biogenic) for methylglyoxal. Both acetylene and acetone have long lifetimes and provide a source of dicarbonyls in the free troposphere. Atmospheric lifetimes of glyoxal and methylglyoxal in the model are 2.9 h and 1.6 h, respectively, mostly determined by photolysis. Simulated dicarbonyl concentrations in continental surface air at northern midlatitudes are in the range 10–100 ppt, consistent with in situ measurements. On a global scale, the highest concentrations are over biomass burning regions, in agreement with glyoxal column observations from the SCIAMACHY satellite instrument. SCIAMACHY and a few ship cruises also suggest a large marine source of dicarbonyls missing from our model. The global source of SOA from the irreversible uptake of dicarbonyls in GEOS-Chem is 11 Tg C a−1, including 2.6 Tg C a−1 from glyoxal and 8 Tg C a−1 from methylglyoxal; 90% of this source takes place in clouds. The magnitude of the global SOA source from dicarbonyls is comparable to that computed in GEOS-Chem from the standard mechanism involving reversible partitioning of semivolatile products from the oxidation of monoterpenes, sesquiterpenes, isoprene, and aromatics.Earth and Planetary SciencesEngineering and Applied Science

The effects of acute wild blueberry supplementation on the cognition of 7-10 year old schoolchildren

Purpose: Previous evidence suggests consumption of flavonoids, a sub-class of polyphenols, is associated with improved cognitive function across the lifespan. In particular, acute intervention of a flavonoid-rich wild blueberry (WBB) drink has been shown to boost executive function (EF), short-term memory and mood 2-6 h post-consumption in 7-10 yr old children. However, confirmation of the aspects of EF and memory susceptible to WBB ingestion is required, particularly during childhood, a critical period of neurological development. In addition, the child literature on berry-flavonoid supplementation and cognition highlights the potential for such interventions to elicit positive benefits to real world educational scenarios, such as reading; a complex ability which relies upon aspects of cognition already known to improve following WBB. Methods: Here we examined which aspects of EF and memory are susceptible to acute WBB, as well as investigating whether acute WBB could further benefit reading ability. Fifty-four healthy children, aged 7-10 yrs, consumed a 200ml WBB drink (253mg anthocyanins) or a matched placebo according to a randomised, single-blind, parallel groups design. Verbal memory (Auditory Verbal Learning Task; AVLT), EF (Modified Attention Network Task; MANT), and reading efficiency (Test of Word Reading Efficiency-2; TOWRE-2) were assessed at baseline and 2 h post consumption. Results: For the MANT, significantly quicker RTs were observed for WBB participants when compared to placebo participants on 120 ms trials, without cost to accuracy. Furthermore, WBB participants showed enhanced verbal memory performance on the AVLT, recalling more words than placebo participants on short delay and memory acquisition measures post-consumption. Despite these significant improvements in cognitive performance, no significant effects were observed for reading measures. Conclusion: Consumption of WBB was found to significantly improve memory and attentional aspects of EF. This indicates that a flavonoid-rich blueberry product, equivalent to 240 g or 1½ cups of fresh blueberries can provide acute cognitive benefits in children. These findings support accumulating evidence that flavonoid-rich products are beneficial for healthy brain function, particularly during critical developmental periods. However, the lack of findings relating to reading ability suggested acute WBB may not be sufficient to elicit benefits to reading. Chronic supplementation and other more sensitive reading measures should be considered for examining the effects of WBB on such a complex skill in the future

Response to Questions in the First White Paper, \u27Modernizing the Communications Act\u27

The House Energy and Commerce Committee has begun a process to review and update the Communications Act of 1934, last revised in any material way in 1996. As the Committee begins the review process, this paper responds to questions posed by the Committee that all relate, in fundamental ways, to the question: What should a modern Communications Act look like? The Response advocates a clean slate approach under which the regulatory silos that characterize the current statute would be eliminated, along with almost all of the ubiquitous \u27public interest\u27 delegation of authority found throughout the Communications Act. The replacement regime would have at its core a new competition-based standard that, except in limited circumstances, would require that the FCC\u27s regulatory activities be tied to findings of consumer harm resulting from lack of sufficient competition. The FCC\u27s authority to adopt broad anticipatory rules on an ex ante basis would be substantially circumscribed, and the agency would be required to rely more heavily than is presently the case on ex post adjudication of individual complaints alleging specific abuses of market power and consumer harm. Some aspects of the FCC\u27s current jurisdiction, such as privacy and data security regulation, might be transferred to the FTC in light of the FTC\u27s institutional competence in these areas

Response to Questions in the First White Paper, \u27Modernizing the Communications Act\u27

The House Energy and Commerce Committee has begun a process to review and update the Communications Act of 1934, last revised in any material way in 1996. As the Committee begins the review process, this paper responds to questions posed by the Committee that all relate, in fundamental ways, to the question: What should a modern Communications Act look like? The Response advocates a clean slate approach under which the regulatory silos that characterize the current statute would be eliminated, along with almost all of the ubiquitous \u27public interest\u27 delegation of authority found throughout the Communications Act. The replacement regime would have at its core a new competition-based standard that, except in limited circumstances, would require that the FCC\u27s regulatory activities be tied to findings of consumer harm resulting from lack of sufficient competition. The FCC\u27s authority to adopt broad anticipatory rules on an ex ante basis would be substantially circumscribed, and the agency would be required to rely more heavily than is presently the case on ex post adjudication of individual complaints alleging specific abuses of market power and consumer harm. Some aspects of the FCC\u27s current jurisdiction, such as privacy and data security regulation, might be transferred to the FTC in light of the FTC\u27s institutional competence in these areas