Sarma Phase in Trapped Unbalanced Fermi Gases

We consider a trapped unbalanced Fermi gas at nonzero temperatures where the superfluid Sarma phase is stable. We determine in particular the phase boundaries between the superfluid, normal, and phase separated regions of the trapped unbalanced Fermi mixture. We show that the physics of the Sarma phase is sufficient to understand the recent observations of Zwierlein et al. [Science 311, 492 (2006); Nature 442, 54 (2006)] and indicate how the apparent contradictions between this experiment and the experiment of Partridge et al. [Science 311, 503 (2006)] may be resolved.Comment: Replaced with published version; 4 pages, 3 figure

Resonant Superfluidity in an Optical Lattice

We study a system of ultracold fermionic Potassium (40K) atoms in a three-dimensional optical lattice in the vicinity of an s-wave Feshbach resonance. Close to resonance, the system is described by a multi-band Bose-Fermi Hubbard Hamiltonian. We derive an effective lowest-band Hamiltonian in which the effect of the higher bands is incorporated by a self-consistent mean-field approximation. The resulting model is solved by means of Generalized Dynamical Mean-Field Theory. In addition to the BEC/BCS crossover we find a phase transition to a fermionic Mott insulator at half filling, induced by the repulsive fermionic background scattering length. We also calculate the critical temperature of the BEC/BCS-state and find it to be minimal at resonance.Comment: 19 pages, 3 figure

A thermionic energy converter with a molybdenum-alumina cermet emitter

A study is made of the properties of cermets as electrode materials for thermionic energy converters. For thermodynamic reasons it is expected that all cermets composed of pure Mo and refractory oxides have the same bare work function. From data on the work function of Mo in an oxygen atmosphere this bare work function is estimated to be F=4.9 eV (at T=1400¿°C). Experimentally, the bare work function of Al2O3-Mo cermets was found to be F=4.5 eV, independent of the relative amounts of Al2O3 and Mo. The cesiated work function of the Al2O3-Mo cermets was found to be 0.15 eV lower than the cesiated work function of pure Mo. The bare work function of Mo3Al was found to be F=4.0 eV. The cesiated work function of Mo3Al at collector temperature conditions was 0.3 eV lower than the cesiated work function of pure Mo. The electrical power density of a diode with an Al2O3-Mo cermet emitter was 0.4 W/cm2 at 1300¿°C. The barrier index at this temperature was 2.36 V. The high barrier index is attributed to a high plasma voltage drop Vd=0.91 V

Beetle eater beheerst de aspergekever bij de oogst van groene asperges in 2010

In Canada is een grote stofzuiger die voor of achter een tractor bevestigd kan worden “Beetle Eater” genaamd, gebruikt ter bestrijding van de coloradokever in aardappelen. Biologische telers hebben zo’n apparaat gekocht om hem in te zetten ter bestrijding van de wortelvlieg in peen. De resultaten vielen tegen en het apparaat is na twee jaar experimenteren niet meer gebruikt. In 2010 is de machine getest in groene asperges tegen de aspergekever op een gangbaar bedrijf in Noord - Brabant. Omdat groene asperges bij gunstige weersomstandigheden dagelijks geoogst worden, is het lastig om tegen dit insect gewasbeschermingsmiddelen in te zetten vanwege de veiligheidstermijn. Door de Beetle eater 1 of 2 keer (direct na elkaar) in te zetten worden de aspergekevers met 50 of 74% gereduceerd. De asperge oogsters merkten meteen wanneer de machine was ingezet omdat het aantal eitjes op de aspergestengels duidelijk afnam. Door de Beetle eater regelmatig in te zetten bleven het aantal afgezette eitjes op de stengels beperkt en zijn het gehele seizoen geen groene asperges bij deze teler afgekeurd en geen asperges daardoor aangemerkt als kwaliteit II. Een aandachtspunt is wel dat na iedere behandeling aspergestengels afbreken. Dit komt enerzijds omdat de rijafstand niet correspondeerde met de zuigmonden van de Beetle eater (scheelde 5 cm) en anderzijds omdat bij oudere percelen de aspergestengels verder uit het hart van de rug kunnen groeien. Door de zuigmond aan te passen (verbreden en iets te vergroten) is de verwachting dat het afbreken van de stengels beperkt wordt

Causality and universality in low-energy quantum scattering

We generalize Wigner's causality bounds and Bethe's integral formula for the effective range to arbitrary dimension and arbitrary angular momentum. Moreover, we discuss the impact of these constraints on the separation of low- and high-momentum scales and universality in low-energy quantum scattering.Comment: 9 pages, 1 figure, published versio

Dynamics of cold bosons in optical lattices: Effects of higher Bloch bands

The extended effective multiorbital Bose-Hubbard-type Hamiltonian which takes into account higher Bloch bands, is discussed for boson systems in optical lattices, with emphasis on dynamical properties, in relation with current experiments. It is shown that the renormalization of Hamiltonian parameters depends on the dimension of the problem studied. Therefore, mean field phase diagrams do not scale with the coordination number of the lattice. The effect of Hamiltonian parameters renormalization on the dynamics in reduced one-dimensional optical lattice potential is analyzed. We study both the quasi-adiabatic quench through the superfluid-Mott insulator transition and the absorption spectroscopy, that is energy absorption rate when the lattice depth is periodically modulated.Comment: 23 corrected interesting pages, no Higgs boson insid

Causality and the effective range expansion

We derive the generalization of Wigner's causality bounds and Bethe's integral formula for the effective range parameter to arbitrary dimension and arbitrary angular momentum. We also discuss the impact of these constraints on the separation of low- and high-momentum scales and universality in low-energy scattering. Some of our results were summarized earlier in a letter publication. In this work, we present full derivations and several detailed examples.Comment: 27 pages, 5 figures, explicit examples added, typos corrected, final versio

Ground states and dynamics of population-imbalanced Fermi condensates in one dimension

By using the numerically exact density-matrix renormalization group (DMRG) approach, we investigate the ground states of harmonically trapped one-dimensional (1D) fermions with population imbalance and find that the Larkin-Ovchinnikov (LO) state, which is a condensed state of fermion pairs with nonzero center-of-mass momentum, is realized for a wide range of parameters. The phase diagram comprising the two phases of i) an LO state at the trap center and a balanced condensate at the periphery and ii) an LO state at the trap center and a pure majority component at the periphery, is obtained. The reduced two-body density matrix indicates that most of the minority atoms contribute to the LO-type quasi-condensate. With the time-dependent DMRG, we also investigate the real-time dynamics of a system of 1D fermions in response to a spin-flip excitation.Comment: 20 pages, 15 figures, accepted for publication in New Journal of Physic

FSH isoform pattern in classic galactosemia

Female classic galactosemia patients suffer from primary ovarian insufficiency (POI). The cause for this long-term complication is not fully understood. One of the proposed mechanisms is that hypoglycosylation of complex molecules, a known secondary phenomenon of galactosemia, leads to FSH dysfunction. An earlier study showed less acidic isoforms of FSH in serum samples of two classic galactosemia patients compared to controls, indicating hypoglycosylation. In this study, FSH isoform patterns of five classic galactosemia patients with POI were compared to the pattern obtained in two patients with a primary glycosylation disorder (phosphomannomutase-2-deficient congenital disorders of glycosylation, PMM2-CDG) and POI, and in five postmenopausal women as controls. We used FPLC chromatofocussing with measurement of FSH concentration per fraction, and discovered that there were no significant differences between galactosemia patients, PMM2-CDG patients and postmenopausal controls. Our results do not support that FSH dysfunction due to a less acidic isoform pattern because of hypoglycosylation is a key mechanism of POI in this disease