Terrorism on Trial: The President’s Constitutional Authority to Order the Prosecution of Suspected Terrorists by Military Commission

Sverige har sedan 1960-talet varit ett invandringsland. Av befolkningen är idag cirka 15 % födda i annat land. Andelen av befolkningen som är utlands-födda är i nivå med länder som USA och Tyskland. Andelen är inte bara betydligt högre än i övriga Nordiska länder, utan också högre än länder som Nederländerna, Frankrike och Storbritannien (RiR 2008:13).1 Utrikes födda beräknas utgöra en dryg fjärdedel av arbetskraftsreserven i Sverige. Under senare år har olika insatser genomförts med avsikt att öka arbetskraftsdelta-gandet

Jamming, two-fluid behaviour and 'self-filtration' in concentrated particulate suspensions

We study the flow of model experimental hard sphere colloidal suspensions at high volume fraction $\Phi$ driven through a constriction by a pressure gradient. Above a particle-size dependent limit $\Phi_0$, direct microscopic observations demonstrate jamming and unjamming--conversion of fluid to solid and vice versa--during flow. We show that such a jamming flow produces a reduction in colloid concentration $\Phi_{x}$ downstream of the constriction. We propose that this `self-filtration' effect is the consequence of a combination of jamming of the particulate part of the system and continuing flow of the liquid part, i.e. the solvent, through the pores of the jammed solid. Thus we link the concept of jamming in colloidal and granular media with a 'two-fluid'-like picture of the flow of concentrated suspensions. Results are also discussed in the light of Osborne Reynolds' original experiments on dilation in granular materials.Comment: 4 pages, 3 figure

Fluctuations in coral health of four common inshore reef corals in response to seasonal and anthropogenic changes in water quality

Environmental drivers of coral condition (maximum quantum yield, symbiont density, chlorophyll a content and coral skeletal growth rates) were assessed in the equatorial inshore coastal waters of Singapore, where the amplitude of seasonal variation is low, but anthropogenic influence is relatively high. Water quality variables (sediments, nutrients, trace metals, temperature, light) explained between 52 and 83% of the variation in coral condition, with sediments and light availability as key drivers of foliose corals (Merulina ampliata, Pachyseris speciosa), and temperature exerting a greater influence on a branching coral (Pocillopora damicornis). Seasonal reductions in water quality led to high chlorophyll a concentrations and maximum quantum yields in corals, but low growth rates. These marginal coral communities are potentially vulnerable to climate change, hence, we propose water quality thresholds for coral growth with the aim of mitigating both local and global environmental impacts

Progress in the study of CdZnTe strip detectors

We report new performance measurements and computer simulations of a sub-millimeter pitch CdZnTe strip detector under study as a prototype imaging spectrometer for astronomical x-ray and gamma-ray observations. The prototype is 1.5 mm thick with 375 micron strip pitch in both the x and y dimensions. Previously reported work included demonstrations of half-pitch spatial resolution (approximately 190 microns) and good energy resolution and spectral uniformity. Strip detector efficiency measurements have also been presented. A model that includes the photon interaction, carrier transport and the electronics was developed that qualitatively reproduced the measurements. The new studies include measurements of the CdZnTe transport properties for this prototype in an effort to resolve quantitative discrepancies between the measurements and the simulations. Measurements of charge signals produced by laser pulses and (alpha) -rays are used to determine these transport properties. These are then used in the model to predict gamma-ray efficiencies that are compared with the data. The imaging performance of the detector is studied by scanned laser and gamma beam spot measurements. The results support the model\u27s prediction of nearly linear sharing of the charge for interactions occurring in the region between electrodes. The potential for strip detectors with spatial resolution much finer than the strip pitch is demonstrated. A new design scheme for strip detectors is shortly discussed

The initial stellar mass function from random sampling in hierarchical clouds II: statistical fluctuations and a mass dependence for starbirth positions and times

Observed variations in the slope of the initial stellar mass function are shown to be consistent with a model in which the protostellar gas is randomly sampled from hierarchical clouds at a rate proportional to the square root of the local density. RMS variations in the IMF slope around the Salpeter value are +/- 0.4 when only 100 stars are observed, and +/- 0.1 when 1000 stars are observed. The hierarchical-sampling model also reproduces the tendency for massive stars to form closer to the center of a cloud, at a time somewhat later than the formation time of the lower mass stars. The assumed density dependence for the star formation rate is shown to be appropriate for turbulence compression, magnetic diffusion, gravitational collapse, and clump or wavepacket coalescence. The low mass flattening in the IMF comes from the inability of gas to form stars below the thermal Jeans mass at typical temperatures and pressures. Consideration of heating and cooling processes indicate why the thermal Jeans mass should be nearly constant in normal environments, and why it might increase in some starburst regions. The steep IMF in the extreme field is not explained by the model, but other origins are suggested.Comment: 21 pages, 8 figures, scheduled for ApJ vol. 515, April 10, 199

Quantum interference structures in trapped ion dynamics beyond the Lamb-Dicke and rotating wave approximations

We apply wave packet methods to study an ion-trap system in the strong excitation regime imposing neither the rotating wave nor the Lamb-Dicke approximations. By this approach we show the existence of states with restricted phase space evolution, as a genuine consequence of quantum interference between wave packet fractions. A particular instance of such a state oscillates between maximal entanglement and pure disentanglement between the constitute subsystems. The characteristic crossover time is very rapid making them suitable for state preparations of EPR or Schrodinger cat states. Over longer time periods the dynamics of these states exhibits collapse-revival patterns with well resolved fractional revivals in autocorrelation, inversion and entanglement.Comment: 11 pages, 5 figures. Replaced with revised version. Phys. Rev. A 77, 053808 (2008

Time scales in shear banding of wormlike micelles

Transient stress and birefringence measurements are performed on wormlike micellar solutions that "shear band", i.e. undergo flow-induced coexistence of states of different viscosities along a constant stress "plateau". Three well-defined relaxation times are found after a strain rate step between two banded flow states on the stress plateau. Using the Johnson-Segalman model, we relate these time scales to three qualitatively different stages in the evolution of the bands and the interface between them: band destabilization, reconstruction of the interface, and travel of the fully formed interface. The longest timescale is then used to estimate the magnitude of the (unknown) "gradient" terms that must be added to constitutive relations to explain the history independence of the steady flow and the plateau stress selection

Fcc-bcc transition for Yukawa interactions determined by applied strain deformation

Calculations of the work required to transform between bcc and fcc phases yield a high-precision bcc-fcc transition line for monodisperse point Yukawa (screened-Couloumb) systems. Our results agree qualitatively but not quantitatively with previously published simulations and phenomenological criteria for the bcc-fcc transition. In particular, the bcc-fcc-fluid triple point lies at a higher inverse screening length than previously reported.Comment: RevTex4, 9 pages, 6 figures. Discussion of phase coexistence extended, a few other minor clarifications added, referencing improved. Accepted for publication by Physical Review

Quantum fluctuations in the mazer

Quantum fluctuations in the mazer are considered, arising either from the atomic motion or from the quantized intracavity field. Analytical results, for both the meza and the hyperbolic secant mode profile, predict for example an attenuation of tunneling resonances due to such fluctuations. The case of a Gaussian mode profile is studied numerically using a wave packet propagation approach. The method automatically takes into account fluctuations in the atomic motion and the dynamics is especially considered at or adjacent to a tunnel resonance. We find that the system evolution is greatly sensitive to the atom-field detuning, bringing about a discussion about the concept of adiabaticity in this model. Further, a novel collapse-revival phenomena is demonstrated, originating from the quantum fluctuations in the atomic motion rather from field fluctuations as is normally the case.Comment: 15 pages, 8 figures. Replaced with final versio