Thermophoresis, the Soret effect, depletes a high concentration of a polyethylene glycol polymer solution from the hot region and builds a concentration gradient. In such a solution, solutes of small concentration experience thermophoresis and polyethylene glycol concentration-dependent restoring forces. We report that by using focused laser heating and varying the polyethylene glycol concentration one observes geometrical localizations of solutes like DNA and RNA into patterns such as a ring. For DNA up to 5.6 kbp, the ring size decreases following a behavior analogous to a gel electrophoresis separation. Above 5.6 kbp, the ring diameter increases with the DNA length. Mixtures of DNA and RNA can be separated as well as different RNA lengths. Separation of colloids is also observed. The experiments might be relevant for the separation of small RNA ribozymes in an early stage of life.

Here we show that the surface of human cervical epithelial cells demonstrates substantially different fractal behavior when the cell becomes cancerous. Analyzing the adhesion maps of individual cervical cells, which were obtained using the atomic force microscopy operating in the HarmoniX mode, we found that cancerous cells demonstrate simple fractal behavior, whereas normal cells can only be approximated at best as multifractal. Tested on $\sim 300$ cells collected from 12 humans, the fractal dimensionality of cancerous cells is found to be unambiguously higher than that for normal cells.

We propose a method to prepare and verify spatial quantum superpositions of a nanometer-sized object separated by distances of the order of its size. This method provides unprecedented bounds for objective collapse models of the wave function by merging techniques and insights from cavity quantum optomechanics and matter-wave interferometry. An analysis and simulation of the experiment is performed taking into account standard sources of decoherence. We provide an operational parameter regime using present-day and planned technology.

We determined the experimental value of the $g$ factor of the electron bound in hydrogenlike ${}^{28}\mathrm{Si}^{13+}$ by using a single ion confined in a cylindrical Penning trap. From the ratio of the ion’s cyclotron frequency and the induced spin flip frequency, we obtain $g=1.9953489587(5)(3)(8)$. It is in excellent agreement with the state-of-the-art theoretical value of 1.995 348 958 0(17), which includes QED contributions up to the two-loop level of the order of $(Z\alpha {)}^2$ and $(Z\alpha {)}^4$ and represents a stringent test of bound-state quantum electrodynamics calculations.

Coherent structures appear in a concentrated suspension of swimming bacteria. While transport phenomena in a suspension have been studied extensively, how energy is transported from the individual cell scale to the larger mesoscale remains unclear. In this study, we carry out the first successful measurement of the three-dimensional velocity field in a dense suspension of bacteria. The results show that most of the energy generated by individual bacteria dissipates on the cellular scale. Only a small amount of energy is transported to the mesoscale, but the gain in swimming velocity and mass transport due to mesoscale coherent structures is enormous. These results indicate that collective swimming of bacteria is efficient in terms of energy. This paper sheds light on how energy can be transported toward smaller wave numbers in the Stokes flow regime.

We report the first detection of the gravitational lensing of the cosmic microwave background through a measurement of the four-point correlation function in the temperature maps made by the Atacama Cosmology Telescope. We verify our detection by calculating the levels of potential contaminants and performing a number of null tests. The resulting convergence power spectrum at 2° angular scales measures the amplitude of matter density fluctuations on comoving length scales of around 100 Mpc at redshifts around 0.5 to 3. The measured amplitude of the signal agrees with Lambda cold dark matter cosmology predictions. Since the amplitude of the convergence power spectrum scales as the square of the amplitude of the density fluctuations, the $4\sigma$ detection of the lensing signal measures the amplitude of density fluctuations to 12%.

For the first time, measurements of the cosmic microwave background radiation (CMB) alone favor cosmologies with $w=-1$ dark energy over models without dark energy at a 3.2-sigma level. We demonstrate this by combining the CMB lensing deflection power spectrum from the Atacama Cosmology Telescope with temperature and polarization power spectra from the Wilkinson Microwave Anisotropy Probe. The lensing data break the geometric degeneracy of different cosmological models with similar CMB temperature power spectra. Our CMB-only measurement of the dark energy density ${\Omega }_{\Lambda }$ confirms other measurements from supernovae, galaxy clusters, and baryon acoustic oscillations, and demonstrates the power of CMB lensing as a new cosmological tool.

This Letter reports the first direct observation of muon antineutrino disappearance. The MINOS experiment has taken data with an accelerator beam optimized for ${\overline{\nu }}_{\mu }$ production, accumulating an exposure of $1.71\times {10}^{20}$ protons on target. In the Far Detector, 97 charged current ${\overline{\nu }}_{\mu }$ events are observed. The no-oscillation hypothesis predicts 156 events and is excluded at $6.3\sigma$. The best fit to oscillation yields $|\Delta {\overline{m}}^2|=[{3.36}_{-0.40}^{+0.46}(\mathrm{stat})\pm 0.06(\mathrm{syst})]\times {10}^{-3}{\mathrm{eV}}^2$, ${sin}^2(2\overline{\theta })={0.86}_{-0.12}^{+0.11}(\mathrm{stat})\pm 0.01(\mathrm{syst})$. The MINOS ${\nu }_{\mu }$ and ${\overline{\nu }}_{\mu }$ measurements are consistent at the 2.0% confidence level, assuming identical underlying oscillation parameters.

Out-of-equilibrium disordered systems may form memories of external driving in a remarkable fashion. The system “remembers” multiple values from a series of training inputs yet “forgets” nearly all of them at long times despite the inputs being continually repeated. Here, learning and forgetting are inseparable aspects of a single process. The memory loss may be prevented by the addition of noise. We identify a class of systems with this behavior, giving as an example a model of non-Brownian suspensions under cyclic shear.

We present a study of the dijet invariant mass spectrum in events with two jets produced in association with a $W$ boson in data corresponding to an integrated luminosity of $4.3{\mathrm{fb}}^{-1}$ collected with the D0 detector at $\sqrt{s}=1.96\mathrm{TeV}$. We find no evidence for anomalous resonant dijet production and derive upper limits on the production cross section of an anomalous dijet resonance recently reported by the CDF Collaboration, investigating the range of dijet invariant mass from 110 to $170\mathrm{GeV}/c^2$. The probability of the D0 data being consistent with the presence of a dijet resonance with 4 pb production cross section at $145\mathrm{GeV}/c^2$ is $8\times {10}^{-6}$.

Near-field radiation allows heat to propagate across a small vacuum gap at rates several orders of magnitude above that of far-field, blackbody radiation. Although heat transfer via near-field effects has been discussed for many years, experimental verification of this theory has been very limited. We have measured the heat transfer between two macroscopic sapphire plates, finding an increase in agreement with expectations from theory. These experiments, conducted near 300 K, have measured the heat transfer as a function of separation over mm to $\mu \mathrm{m}$ and as a function of temperature differences between 2.5 and 30 K. The experiments demonstrate that evanescence can be put to work to transfer heat from an object without actually touching it.

Heterogeneous microscale dynamics in the martensitic phase transition of cobalt is investigated with real-time x-ray scattering. During the transformation of the high-temperature face-centered cubic phase to the low-temperature hexagonal close-packed phase, the structure factor evolution suggests that an initial rapid local transformation is followed by a slower period during which strain relaxes. Coherent x-ray scattering measurements performed during the latter part of the transformation show that the kinetics is dominated by discontinuous sudden changes—avalanches. The spatial size of observed avalanches varies widely, from 100 nm to $10\mu \mathrm{m}$, the size of the x-ray beam. An empirical avalanche amplitude quantifies this behavior, exhibiting a power-law distribution. The avalanche rate decreases with inverse time since the onset of the transformation.

Recent experiments on the conductance of thin, narrow superconducting strips have found periodic fluctuations, as a function of the perpendicular magnetic field, with a period corresponding to approximately two flux quanta per strip area [A. Johansson et al., Phys. Rev. Lett. 95, 116805 (2005)]. We argue that the low-energy degrees of freedom responsible for dissipation correspond to vortex motion. Using vortex-charge duality, we show that the superconducting strip behaves as the dual of a quantum dot, with the vortices, magnetic field, and bias current respectively playing the roles of the electrons, gate voltage, and source-drain voltage. In the bias-current versus magnetic-field plane, the strip conductance displays regions of small vortex conductance (i.e., small electrical resistance) that we term “Weber blockade” diamonds, which are dual to Coulomb blockade diamonds in quantum dots.

An extended Josephson junction can be described as a microwave cavity coupled to a Josephson oscillator. This is formally equivalent to a Fabry-Perot cavity with a freely vibrating mirror, where it has been shown that radiation pressure from photons in the cavity can reduce (increase) the vibrations of the mirror, effectively cooling (heating) it. We demonstrate that, similarly, the superconducting phase difference across a Josephson junction—the Josephson phase—can be “cooled” or “heated” by microwave excitation of the junction and that both these effects increase with microwave power.

A poorly understood step in the transition from a chemical to a biological world is the emergence of self-replicating molecular systems. We study how a precursor for such a replicator might arise in a hydrothermal RNA reactor, which accumulates longer sequences from unbiased monomer influx and random ligation. In the reactor, intra- and intermolecular base pairing locally protects from random cleavage. By analyzing stochastic simulations, we find temporal sequence correlations that constitute a signature of information transmission, weaker but of the same form as in a true replicator.

We report on the first direct measurement of the proton separation energy for the proton-unbound nucleus ${}^{69}\mathrm{Br}$. Bypassing the ${}^{68}\mathrm{Se}$ waiting point in the rp process is directly related to the $2p$-capture rate through ${}^{69}\mathrm{Br}$, which depends exponentially on the proton separation energy. We find a proton separation energy for ${}^{69}\mathrm{Br}$ of $S_p({}^{69}\mathrm{Br})=-{785}_{-40}^{+34}\mathrm{keV}$; this is less bound compared to previous predictions which have relied on uncertain theoretical calculations. The influence of the extracted proton separation energy on the rp process occurring in type I x-ray bursts is examined within the context of a one-zone burst model.

Discontinuous time derivatives are used to model threshold-dependent switching in such diverse applications as dry friction, electronic control, and biological growth. In a continuous flow, a discontinuous derivative can generate multiple outcomes from a single initial state. Here we show that well-defined solution sets exist for flows that become multivalued due to grazing a discontinuity. Loss of determinism is used to quantify dynamics in the limit of infinite sensitivity to initial conditions, then applied to the dynamics of a superconducting resonator and a negatively damped oscillator.

We perform high-precision measurements of the condensation temperature of a harmonically trapped atomic Bose gas with widely tunable interactions. For weak interactions we observe a negative shift of the critical temperature in excellent agreement with mean-field theory. However for sufficiently strong interactions we clearly observe an additional positive shift, characteristic of beyond-mean-field critical correlations. We also discuss nonequilibrium effects on the apparent critical temperature for both very weak and very strong interactions.

We show that the Bogoliubov–de Gennes equations for nuclear ground-state wave functions support solutions in which the condensate has a mixture of spin-singlet and spin-triplet pairing. We find that such mixed-spin condensates do not occur when there are equal numbers of neutrons and protons, but only when there is an isospin imbalance. Using a phenomenological Hamiltonian, we predict that such nuclei may occur in the physical region within the proton dripline. We also solve the Bogoliubov–de Gennes equations with variable constraints on the spin-singlet and spin-triplet pairing amplitudes. For nuclei that exhibit this new pairing behavior, the resulting energy surface can be rather soft, suggesting that there may be low-lying excitations associated with the spin mixing.

We communicate results on correlation functions for the spin-$1/2$ Heisenberg chain in two particularly important cases: (a) for the infinite chain at arbitrary finite temperature $T$, and (b) for finite chains of arbitrary length $L$ in the ground state. In both cases we present explicit formulas expressing the short-range correlators in a range of up to seven lattice sites in terms of a single function $\omega$ encoding the dependence of the correlators on $T$ ($L$). These formulas allow us to obtain accurate numerical values for the correlators and derived quantities like the entanglement entropy. By calculating the low $T$ (large $L$) asymptotics of $\omega$ we show that the asymptotics of the static correlation functions at any finite distance are $T^2$ ($1/L^2$) terms. We obtain exact and explicit formulas for the coefficients for up to eight sites.