Quantum phases of Bose-Fermi mixtures in optical lattices.

We analyze the ground-state phase diagram of an ultracold Bose-Fermi mixture placed in an optical lattice. The quantum phases involve pairing of fermions and one or several bosons. Depending on the physical parameters these composites can form a Fermi liquid, a density wave, a superfluid or a domain insulator. We determine by means of a mean-field formalism the phase boundaries for finite tunneling, and analyze the experimental feasibility of these sort of phases.

Ozone episodes in Southern Lower Saxony (FRG) and their impact on the susceptibility of cereals to fungal pathogens.

Spring wheat (Triticum aestivum L.) and spring barley (Hordeum vulgare L.) plants were exposed to simulated ozone (O(3)) episodes (7 h day(-1) for 7 days) at maximum concentrations of 120, 180 and 240 microg m(-3) O(3), in comparison to a charcoal-filtered air control. Fumigations were conducted in four closed chambers placed in a climate room. Exposures took place prior to inoculation of the plants with six different facultative leaf pathogens. On wheat, significant enhancement of leaf attack by Septoria nodorum Berk. and S. tritici Rob. ex Desm. appeared, particularly on the older leaves and at the highest level of O(3). The same was true for Gerlachia nivalis W. Gams et E. Müll/Fusarium culmorum (W.F.Sm.) Sacc. on wheat and net blotch (Drechslera teres (Sacc.) Shoem.) or G. nivalis leaf spots on barley. Disease development was promoted both on leaves with and without visible injury following exposure to O(3). Sporulation of the two Septoria species increased at 120 and 180 microg m(-3) O(3); however, it was reduced to the level of the control, if 240 microg m(-3) were applied. No significant effects of predisposition were observed with Bipolaris sorokiniana (Sacc.) Shoem. (syn. Helminthosporium sativum Pamm., King et Bakke), the causal agent of spot blotch, neither on wheat nor on barley. Doses and peak concentrations applied in the experiments were in good agreement with measurements of ambient ozone in Southern Lower Saxony, FRG. Six years' ozone data (1984-1989) revealed the annual occurrence of between 3 and 11 ozone episodes with potentially harmful effects on cereals (three or more consecutive 'ozone days' with 8-h means above 80 microg m(-3)). The frequency of ozone episodes followed by weather periods favourable for infections by facultative pathogens was higher in years with low O(3) pollution than in ozone-rich years, and varied between one and five cases per season. The number of ozone days during the main growing season of cereals (1 April until 31 August) varied from 25 in 1984 to 98 in 1989. However, only 7.9% of ozone days during the 6 years examined were concurrent with weather conditions suitable for fungal infections. It is concluded that the majority of leaf infections in the field happens under low-level concentrations of photooxidants.

Binary millisecond pulsar discovery via gamma-ray pulsations.

Millisecond pulsars, old neutron stars spun up by accreting matter from a companion star, can reach high rotation rates of hundreds of revolutions per second. Until now, all such "recycled" rotation-powered pulsars have been detected by their spin-modulated radio emission. In a computing-intensive blind search of gamma-ray data from the Fermi Large Area Telescope (with partial constraints from optical data), we detected a 2.5-millisecond pulsar, PSR J1311-3430. This unambiguously explains a formerly unidentified gamma-ray source that had been a decade-long enigma, confirming previous conjectures. The pulsar is in a circular orbit with an orbital period of only 93 minutes, the shortest of any spin-powered pulsar binary ever found.

Pulsar discovery by global volunteer computing.

Einstein@Home aggregates the computer power of hundreds of thousands of volunteers from 192 countries to mine large data sets. It has now found a 40.8-hertz isolated pulsar in radio survey data from the Arecibo Observatory taken in February 2007. Additional timing observations indicate that this pulsar is likely a disrupted recycled pulsar. PSR J2007+2722's pulse profile is remarkably wide with emission over almost the entire spin period; the pulsar likely has closely aligned magnetic and spin axes. The massive computing power provided by volunteers should enable many more such discoveries.

Wigner Crystallization in Rapidly Rotating 2D dipolar fermi gases.

We study the competition between the Wigner crystal and the Laughlin liquid states in an ultracold quasi-two-dimensional rapidly rotating polarized fermionic dipolar gas, and find that the Wigner crystal has a lower energy below a critical filling factor. We examine the quantum crystal to liquid transition for different confinements in the third direction. Our analysis of the phonon spectra of the Wigner crystal taking into account the phonon-phonon interactions also shows the stability of the Wigner crystal for sufficiently low filling factors (nu < 1/7).

Atomic Fermi gas in the trimerized kagomé lattice at 2/3 filling.

We study low temperature properties of a spinless interacting Fermi gas in the trimerized kagomé lattice. The case of two fermions per trimer is described by a quantum spin 1/2 model on the triangular lattice with couplings depending on the bond directions. Using exact diagonalizations we show that the system exhibits nonstandard properties of a quantum spin-liquid crystal, combining a planar antiferromagnetic order with an exceptionally large number of low-energy excitations.

Misdiagnosis of fetal heart rate during a twin labour. Case report.

Death of a first twin was unsuspected despite continuous fetal scalp electrode and ultrasound fetal heart rate monitoring. The electrocardiogram of the live second twin was detected via the scalp electrode attached to the dead first twin, and the coincidence of the two recordings was not appreciated.

The cervix-ripening effect of the prostaglandin E analogue sulprostone, before vacuum aspiration in first trimester pregnancy.

The cervix-ripening effect of the prostaglandin E analogue 16-phenoxy-tetranor PGE2 methyl- and sulfonylamide, Sulprostone, was examined in 25 primigravidae and 19 women who had earlier been pregnant. Three hours before vacuum aspiration of a 1st trimester conceptus the patients received an i.m. injection of 0.5 mg Sulprostone and the cervical dilatation was assessed under general anesthesia by means of Hegar dilatators immediately prior to vacuum aspiration. In the primigravida group an average cervical dilatation to 7 mm was obtained, compared with 5 mm in a control group. Further dilatation occurred easily in 74% of the patients, compared with 14% in the control group. In the group of previously pregnant women an average cervical dilatation to 8 mm was obtained, compared with 6 mm in the control group. Further dilatation occurred easily in 86% of the patients, compared with 67% in the controls. Routine use of Sulprostone before vacuum aspiration of a 1st trimester conceptus is not recommended because of the rather high frequency of side effects.

Atomic Bose-Fermi mixtures in an optical lattice.

A mixture of ultracold bosons and fermions placed in an optical lattice constitutes a novel kind of quantum gas, and leads to phenomena, which so far has been discussed neither in atomic physics, nor in condensed matter physics. We discuss the phase diagram at low temperatures, and in the limit of strong atom-atom interactions, and predict the existence of quantum phases that involve pairing of fermions with one or more bosons, or, respectively, bosonic holes. The resulting composite fermions may form, depending on the system parameters, a normal Fermi liquid, a density wave, a superfluid liquid, or an insulator with fermionic domains. We discuss the feasibility for observing such phases in current experiments.

Atomic quantum gases in Kagomé lattices.

We demonstrate the possibility of creating and controlling an ideal and trimerized optical Kagomé lattice, and study the low temperature physics of various atomic gases in such lattices. In the trimerized Kagomé lattice, a Bose gas exhibits a Mott transition with fractional filling factors, whereas a spinless interacting Fermi gas at 2/3 filling behaves as a quantum magnet on a triangular lattice. Finally, a Fermi-Fermi mixture at half-filling for both components represents a frustrated quantum antiferromagnet with a resonating-valence-bond ground state and quantum spin liquid behavior dominated by a continuous spectrum of singlet and triplet excitations. We discuss the method of preparing and observing such a quantum spin liquid employing molecular Bose condensates.