Condensate wave function and elementary excitations of bosonic polar molecules: beyond the first Born approximation

We investigate the condensate wave function and elementary excitations of strongly interacting bosonic polar molecules in a harmonic trap, treating the scattering amplitude beyond the standard first Born approximation (FBA). By using an appropriate trial wave function in the variational method, effects of the leading order correction beyond the FBA have been investigated and shown to be significantly enhanced when the system is close to the phase boundary of collapse. How such leading order effect of going beyond the FBA can be observed in a realistic experiment is also discussed.Comment: 7 pages, 4 figure

Surface core excitons in III-V semiconductors

Recent experiments have shown that the cation core excitons on the (110) surface of many III-V semiconductors have very large binding energies.(^1) They are sometimes reported to be bound by as much as ≳0.8 eV, tightly bound compared to bulk binding energies of ≾0.1 eV. To explore this phenomenon, we have calculated the binding energies and oscillator strengths of core excitons on the (110) surface of GaAs, GaSb, GaP, and InP

Structure and management issues of the emerging ornamental fish trade in Eritrea

Following independence from Ethiopia in 1993, Eritrea resumed exploiting Red Sea and Arabian fish species for the ornamental trade in 1995 as a means to earn foreign exchange from sparsely exploited marine resources. This paper describes the findings of research conducted in 1997, in collaboration with the Eritrean Ministry of Fisheries. The capture, transport and export of aquarium fish were reviewed and potential impacts and the status of management were investigated through liaison with stakeholders and researchers. From 1995 to 1997 two companies exported approximately 60,000 fish per year, mainly to the USA, worth US$65,000 (export value). Seventyfive species (from 22 families) were exported. Damselfishes made up two-thirds of total exports but more valuable families (angelfishes and butterflyfishes) were more economically significant. To earn revenue for Eritrea, a 20% export tax was imposed, although this was calculated from declarations by the operators. The emerging nature of the trade allowed detailed monitoring by the Ministry of Fisheries. However, management efforts were constrained by a lack of capacity for enforcement and baseline research. Several potential effects of the trade exist but other, land-based impacts may be more pressing concerns for Eritrea’s reefs. Research priorities for management are discussed as well as the implications of mariculture of Eritrean species by other nations

Ultrahigh Speed Direct PCR: A Method for Obtaining Y-STR and STR Based Genotypes in Under 20 Minutes

There are many situations in forensic DNA typing where the time it takes to identify an individual is critical. Examples include suspects under arrest and individuals detained at ports of entry. It is also important to identify victims quickly when dealing with mass disasters such as terrorist attacks, airplane crashes and natural disasters in order to notify families. The goal of this project was to develop an ultrafast method for screening saliva samples through the use of rapid direct PCR coupled to microfluidic separation and detection. Fast amplification was achieved through the use of high speed thermocyclers and the experimental optimization of PCR reactants and polymerases. High processivity mutant polymerases were tested at increased speeds along with PCR enhancers. Experimental optimizations and designs were used to ultimately achieve amplification of a 4 loci Y-STR multiplex in 12.5 minutes and a 7 loci STR multiplex in 6.5 minutes. The use of direct PCR not only decreases the overall time of sample processing through the elimination of the extraction, but also, by the removal of the extraction step cuts down on the possibility of contamination to the sample. By using inhibitor resistant fast polymerases such as Omnitaq, BSA and the PEC-1 enhancer, and optimizing cycling conditions, a direct PCR method was developed where amplification from diluted saliva was successfully achieved in 13.5 minutes. The products from these ultrafast amplifications can be coupled to a microfluidic chip for analysis. The electrophoretic system separates the PCR products and provides complete genotypes for both Y and autosomal STR multiplexes in 80 seconds. This permits complete sample processing in under 15 minutes for the rapid direct PCR protocol. This screening method can exclude individuals who do not match evidentiary material and test evidence to see if it is be viable for full analysis. The result of this work was a reliable and robust method for the rapid genotyping of forensic samples which can be used in situations where rapid single sample DNA analysis is necessary

Measurement of the Scintillation Efficiency of Na Recoils in NaI(Tl) down to 10 keV Nuclear Recoil Energy relevant to Dark Matter Searches

We present preliminary results of measurements of the quenching factor for Na recoils in NaI(Tl) at room temperature, made at a dedicated neutron facility at the University of Sheffield. Measurements have been performed with a 2.45 MeV mono-energetic neutron generator in the energy range from 10 keV to 100 keV nuclear recoil energy. A BC501A liquid scintillator detector was used to tag neutrons. Cuts on pulse-shape discrimination from the BC501A liquid scintillator detector and neutron time-of-flight were performed on pulses recorded by a digitizer with a 2 ns sampling time. Measured quenching factors range from 19% to 26%, in agreement with other experiments. From pulse-shape analysis, a mean time of pulses from electron and nuclear recoils are compared down to 2 keV electron equivalent energy.Comment: to appear in Proc. 6th Int. Workshop on the Identification of Dark Matter, 11-16 September 2006, Rhodes, Greece; 6 pages, 4 figures; corrected preliminary theoretical estimation curve plotted in figure

Superfluidity and dimerization in a multilayered system of fermionic polar molecules

We consider a layered system of fermionic molecules with permanent dipole moments aligned by an external field. The dipole interactions between fermions in adjacent layers are attractive and induce inter-layer pairing. Due to competition for pairing among adjacent layers, the mean-field ground state of the layered system is a dimerized superfluid, with pairing only between every-other layer. We construct an effective Ising-XY lattice model that describes the interplay between dimerization and superfluid phase fluctuations. In addition to the dimerized superfluid ground state, and high temperature normal state, at intermediate temperature, we find an unusual dimerized "pseudogap" state with only short-range phase coherence. We propose light scattering experiments to detect dimerization.Comment: 4 pages main text + 3 pages supplemental Appendices, 4 figure

An effective many-body theory for strongly interacting polar molecules

We derive a general effective many-body theory for bosonic polar molecules in strong interaction regime, which cannot be correctly described by previous theories within the first Born approximation. The effective Hamiltonian has additional interaction terms, which surprisingly reduces the anisotropic features of dipolar interaction near the shape resonance regime. In the 2D system with dipole moment perpendicular to the plane, we find that the phonon dispersion scales as \sqrt{|\bfp|} in the low momentum (\bfp) limit, showing the same low energy properties as a 2D charged Bose gas with Coulomb ($1/r$) interactions.Comment: Same as published version (11 pages, 2 figure