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Two-dimensional hard core bosons suffer strong scattering in the high-temperature resistive state at half filling. The dynamical conductivity is calculated using nonperturbative tools such as continued fractions, series expansions, and exact diagonalization. We find a large temperature range with linearly increasing resistivity and broad dynamical conductivity, signaling a breakdown of Boltzmann-Drude quasiparticle transport theory. At zero temperature, a high-frequency peak in appears above a “Higgs mass” gap and corresponds to order-parameter magnitude fluctuations. We discuss the apparent similarity between conductivity of hard core bosons and phenomenological characteristics of cuprates, including the universal scaling of Homes et al.
Nature London 430, 539 2004.

Recent years have seen intensive progress in measuring protein translation. However, how coding sequences determine the efficiency of the process remain unclear. In this talk, I will describe a universally conserved DNA sequence code that appears to determine translation efficiency along genes in all living species. According to this code the first 30–50 codons of genes are deliberately translated with low-efficiency codons. Genome-wide experimental data on ribosomal positioning and density indicates that this design generates a position-specific speed profile that attenuates the ribosomes at the initial section of the genes. This slow "ramp" region may be an optimal and robust means to maximize productivity while reducing traffic jams and the costs of expression.

We study the spectral and morphological characteristics of the diffuse Galactic emission in the WMAP temperature data using a template-based multi-linear regression, and obtain the following results. 1. We confirm previous observations of a bump in the dust-correlated spectrum, consistent with the Draine & Lazarian spinning dust model. 2. We also confirm the "haze" signal in the inner Galaxy, and argue that it does not follow a free-free spectrum as first thought, but instead is synchrotron emission from a hard electron cosmic-ray population. 3. In a departure from previous work, we allow the spectrum of Halpha-correlated emission (which is used to trace the free-free component) to float in the fit, and find that it does not follow the expected free-free spectrum. Instead there is a bump near 50 GHz, modifying the spectrum at the 20% level, which we speculate is caused by spinning dust in the warm ionized medium. 4. The derived cross-correlation spectra are not sensitive to the map zero points, but are sensitive to the choice of CMB estimator. In cases where the CMB estimator is derived by minimizing variance of a linear combination of the WMAP bands, we show that a bias proportional to the cross-correlation of each template and the true CMB is always present. This bias can be larger than any of the foreground signals in some bands. 5. Lastly, we consider the frequency coverage and sensitivity of the Planck mission, and suggest linear combination coefficients for the CMB template that will reduce both the statistical and systematic uncertainty in the synchrotron and haze spectra by more than an order of magnitude.

In a famous example of studying a sleep-like behavior in a phylogenetically ancient model organism, Seymour Benzer – physicists, biologists and one of the founders of the field of molecular biology of behavior – studied the cycles of quiescence of the fruit fly Drosophila. He showed that the period gene is a key regulator of the circadian clock, which is thought to have a role in regulating sleep in mammals. Recently, two additional pathways were shown to play a role in regulating sleep-like behavior in fruit flies and sleep in mice, rabbits and hamsters: Epidermal Growth Factor (EGF) signaling and cyclic-Adenosine MonoPhosphate (cAMP) signaling.

The roundworm C. elegans is in many ways a simpler model organism than the fruit fly, and even more phylogenetically ancient. The worm develops through four larval stages before it reaches adulthood. At the end of each of these stages it exhibits a quiescent behavior called lethargus. David Raizen et al. recently demonstrated that lethargus bears behavioral similarities to sleep, such as reversibility (the worms “wake up”), sensory gating (an elevated threshold for responding to sensory stimuli) and homeostatic control (following deprivation, lethargus is resumed faster and “deeper”). Curiously, lethargus is also phase-locked with cycles in the expression of the worm’s period-like gene. Moreover, EGF and cAMP signaling both appear to have roles in regulating lethargus that resemble their regulation of similar behaviors in flies and mammals. Taken together, these observations suggest a possible ~6´108 year-old genetic link between these phenomena.

I will discuss the opportunities, challenges and risks of studying a sleep-like behavior using C. elegans as a model system. Time permitting, I will discuss some tools and ideas that physics can bring to the study of this everyday – in a sense, universal – natural phenomenon.