Characterisation of a three-dimensional Brownian motor in optical lattices

We present here a detailed study of the behaviour of a three dimensional Brownian motor based on cold atoms in a double optical lattice [P. Sjolund et al., Phys. Rev. Lett. 96, 190602 (2006)]. This includes both experiments and numerical simulations of a Brownian particle. The potentials used are spatially and temporally symmetric, but combined spatiotemporal symmetry is broken by phase shifts and asymmetric transfer rates between potentials. The diffusion of atoms in the optical lattices is rectified and controlled both in direction and speed along three dimensions. We explore a large range of experimental parameters, where irradiances and detunings of the optical lattice lights are varied within the dissipative regime. Induced drift velocities in the order of one atomic recoil velocity have been achieved.Comment: 8 pages, 14 figure

Directed transport of Brownian particles in a double symmetric potential

We investigate the dynamics of Brownian particles in internal state- dependent symmetric and periodic potentials. Although no space or time symmetry of the Hamiltonian is broken, we show that directed transport can appear. We demonstrate that the directed motion is induced by breaking the symmetry of the transition rates between the potentials when these are spatially shifted. Finally, we discuss the possibility of realizing our model in a system of cold particles trapped in optical lattices.Comment: to appear in Physical Review

Influence of the lattice topography on a three-dimensional, controllable Brownian motor

We study the influence of the lattice topography and the coupling between motion in different directions, for a three-dimensional Brownian motor based on cold atoms in a double optical lattice. Due to controllable relative spatial phases between the lattices, our Brownian motor can induce drifts in arbitrary directions. Since the lattices couple the different directions, the relation between the phase shifts and the directionality of the induced drift is non trivial. Here is therefore this relation investigated experimentally by systematically varying the relative spatial phase in two dimensions, while monitoring the vertically induced drift and the temperature. A relative spatial phase range of 2pi x 2pi is covered. We show that a drift, controllable both in speed and direction, can be achieved, by varying the phase both parallel and perpendicular to the direction of the measured induced drift. The experimental results are qualitatively reproduced by numerical simulations of a simplified, classical model of the system

Demonstration of a controllable three-dimensional Brownian motor in symmetric potentials

We demonstrate a Brownian motor, based on cold atoms in optical lattices, where isotropic random fluctuations are rectified in order to induce controlled atomic motion in arbitrary directions. In contrast to earlier demonstrations of ratchet effects, our Brownian motor operates in potentials that are spatially and temporally symmetric, but where spatiotemporal symmetry is broken by a phase shift between the potentials and asymmetric transfer rates between them. The Brownian motor is demonstrated in three dimensions and the noise-induced drift is controllable in our system.Comment: 5 pages, 4 figure

Primary osteosarcoma of the breast: case report

Mammary sarcomas are very uncommon and make up less than 1% of all primary breast malignancies

The FERRUM Project: Experimentally determined metastable lifetimes and transition probabilities for forbidden [Ti II] lines observed in Carinae

ABSTRACT In the spectrum of an emission line region ejected from the massive star Eta Carinae, called the Strontium filament (SrF), forbidden lines from many elements, in particular [SrII] and [Ti II], are observed. These lines are strong in this specific region and valuable for plasma diagnostics. Forbidden lines are not easily produced in laboratory light sources and the atomic parameters for these lines can thus not be measured in a straightforward way. We use a combination of laboratory and astrophysical measurements to determine transition probabilities for the [Ti II] lines. Lifetimes for metastable levels in Ti II are measured using a laser probing technique (LPT) on a stored ion beam at CRYRING, MSL, Stockholm. Branching fractions from some of these levels are derived from HS T /STIS spectra of the SrF. The astrophysical branching fractions are combined with the experimental lifetimes to determine absolute transition probabilities. We report lifetimes for the Ti II levels b 4 P 3¢ 2 , b 2 P 1¢ 2 , c 2 D 3¢ 2 and c 2 D 5¢ 2 , in the range 0.29-17 s, and transition probabilities for eight parity forbidden lines from the levels c 2 D 3¢ 2 and c 2 D 5¢ 2 , along with uncertainty estimates

Amici Curiae Brief of New York law school professors in People v. Harris: Constitutionality of the New York Death Penalty Statute Under the State Constitution\u27s Cruel and Unusual Punishments and Antidiscrimination Clauses

Amici are teachers in New York law schools who have studied the operation of the death penalty for the purpose of teaching the subject, writing about it in scholarly journals, or representing persons accused or convicted of capital crimes. Most of us have worked in the field both as academics and as pro bono counsel for condemned inmates. Collectively, we have had first-hand experience in hundreds of death cases, in dozens of jurisdictions, extending over more than a third of a century. Our experience has convinced us that capital punishment cannot be administered with the fairness, reliability, and freedom from discrimination that a penalty so grave and irreversible requires. This is no accident or transitory condition; it is the consequence of certain innate attributes of the penalty of death. The purpose of our brief is to analyze those attributes and explain why they are fundamentally at war with the Cruel and Unusual Punishments Clause and the Antidiscrimination Clause of New York’s Bill of Rights. We hope to persuade the Court that it should not temporize with the death penalty in the face of this basic incompatibility but should hold the 1995 death penalty statute altogether unconstitutional

Genes targeted by the estrogen and progesterone receptors in the human endometrial cell lines HEC1A and RL95-2

<p>Abstract</p> <p>Background</p> <p>When the steroid hormones estrogen and progesterone bind to nuclear receptors, they have transcriptional impact on target genes in the human endometrium. These transcriptional changes have a critical function in preparing the endometrium for embryo implantation.</p> <p>Methods</p> <p>382 genes were selected, differentially expressed in the receptive endometrium, to study their responsiveness of estrogen and progesterone. The endometrial cell lines HEC1A and RL95-2 were used as experimental models for the non-receptive and receptive endometrium, respectively. Putative targets for activated steroid hormone receptors were investigated by chromatin immunoprecipitation (ChIP) using receptor-specific antibodies. Promoter occupancy of the selected genes by steroid receptors was detected in ChIP-purified DNA by quantitative PCR (qPCR). Expression analysis by reverse transcriptase (RT)-PCR was used to further investigate hormone dependent mRNA expression regulation of a subset of genes.</p> <p>Results</p> <p>ChIP-qPCR analysis demonstrated that each steroid hormone receptor had distinct group of target genes in the endometrial cell lines. After estradiol treatment, expression of estrogen receptor target genes predominated in HEC1A cells (n = 137) compared to RL95-2 cells (n = 35). In contrast, expression of progesterone receptor target genes was higher in RL95-2 cells (n = 83) than in HEC1A cells (n = 7) after progesterone treatment. RT-PCR analysis of 20 genes demonstrated transcriptional changes after estradiol or progesterone treatment of the cell lines.</p> <p>Conclusions</p> <p>Combined results from ChIP-qPCR and RT-PCR analysis showed different patterns of steroid hormone receptor occupancy at target genes, corresponding to activation or suppression of gene expression after hormone treatment of HEC1A and RL95-2 cell lines.</p

Unification of New Zealand's local vertical datums: iterative gravimetric quasigeoid computations

New Zealand uses 13 separate local vertical datums (LVDs) based on normal-orthometric-corrected precise geodetic levelling from 12 different tide-gauges. We describe their unification using a regional gravimetric quasigeoid model and GPS-levelling data on each LVD. A novel application of iterative quasigeoid computation is used, where the LVD offsets computed from earlier models are used to apply additional gravity reductions from each LVD to that model. The solution converges after only three iterations yielding LVD offsets ranging from 0.24 m to 0.58 m with an average standard deviation of 0.08 m. The so-computed LVD offsets agree, within expected data errors, with geodetically levelled height differences at common benchmarks between adjacent LVDs. This shows that iterated quasigeoid models do have a role in vertical datum unification