We propose a simple method to generate a practical SU(2)-Schrödinger-cat state of a single trapped-ion vibration mode and the light field state, using the method based on a quantum system, which is composed of the one-dimensional trapped-ion motion and a single cavity field mode. Moreover, we discuss the methods proposed so far for the generation two-mode maximal quantum entangled state. The detection of such a state is also briefly discussed.

We investigate thermal entanglement in a superconducting-quantum-interference-device qubit coupled to a cavity field. We show that the entanglement can be manipulated by varying temperature and an effective controlling parameter B which depends on the external field and characteristic parameters of the system. We find that there exists a critical value of the controlling parameter B_c. Under a fixed temperature, increasing B can increase entanglement in the regime of B < B_c, while the entanglement decreases with increasing B in the regime of B > B_c.

We study the massless scalar wave propagation in the time dependent Banados Teitelboim-Zanelli black hole background. It is shown that in the quasinormal ringing, both the decay and the oscillation timescales are modified in the time-dependent background.

In the Painlevé and the Lemaitre coordinates, the statistical-mechanical entropies of the Schwarzschild black hole arising from the quantum scalar field are investigated by using the ’t Hooft’s brick wall model. At first sight, it seems that the results would be different from that in the standard Schwarzschild coordinate since both the Painlevé and the Lemaitre spacetimes do not possess the event horizon obviously. However, we prove that the entropies in these coordinates are exactly equivalent to that in the Schwarzschild coordinate.

The behaviour of an excitable system under Gaussian white noise and external periodic forcing is systematically studied. In a large range of noise intensity, the n:1 phase locking patterns are obtained for certain ranges of the input periods, where n input periods give one spike. In the phase locking regimes, the system presents low noise-to-signal ratios and shows better regularities. Out of the regimes the system behaves less regularly and the relations between the noise-to-signal ratio and the noise intensity exhibit typical stochastic resonance phenomena. At a higher noise level, the system shows the characteristic behaviour of the noise.

Bifurcation behaviour of a nonlinear wave system is studied by utilizing the data in solving the nonlinear wave equation. By shifting to the steady wave frame and taking into account the Doppler effect, the nonlinear wave can be transformed into a set of coupled oscillators with its (stable or unstable) steady wave as the fixed point. It is found that in the chosen parameter regime, both mode amplitudes and phases of the wave can bifurcate to limit cycles attributed to the Hopf instability. It is emphasized that the investigation is carried out in a pure nonlinear wave framework, and the method can be used for further exploration of the routes to turbulence.

By employing an inverse-scattering transformation, the exact solution of an N-soliton train in the spin chain with a time-dependent magnetic field is derived. As a special case the one-soliton solution (N = 1) exhibits explicitly the spin precession around the magnetic field and periodic shape-variation induced by the time varying field as well. In terms of the general solution, the inelastic two-soliton collision is analysed. The inelastic collision, by which we mean the soliton shape-change before and after collision, appears generally due to the time varying field.

We study the transport efficiency for x-rays of single-wall carbon nanotubes (SWCNTs) in theory. Three effects, i.e. refraction, absorption and x-ray tunnelling loss, are considered. Our calculation shows that the SWCNT cannot be an x-ray waveguide due to the large x-ray tunnelling loss. If the tunnelling loss can be reduced effectively, a nanotube could be a waveguide.

The longitudinally polarized Drell-Yan process is one of the most powerful tools to probe the structure of hadrons. By means of the recent formalism of the polarized proton-deuteron (pd) Drell-Yan, we calculate the ratio of the proton-deuteron Drell-Yan cross section to the proton-proton (pp) one Δ\σ_pd/2Δσ_pp in the polarized case. The theoretical results can be compared with future experimental data to confirm the nuclear effect due to the 6-quark cluster in deuteron.

The properties of the α decay nuclei of ³¹⁰126, ²⁹²120 and ²⁹⁸114 are investigated in the deformed relativistic mean-field model. The nuclear properties are investigated with the TMA and NL-Z2 parameter sets, and compared with Moller’s result [At. Data Nucl. Data Tables 59 (1995) 185]. The results show that the α decay energy increases systematically with the increasing proton number. Meanwhile, the α decay energy has a minimum value at the point of shell closure. It is also found that of the three nuclei, ²⁹²120 is the more likely to be the next doubly magic nucleus.

We use a procedure to extract valuable information regarding the p-wave halos in ⁸B and ¹¹Be from the measured nuclear asymptotic normalization coefficients. With this procedure, we evaluate the probabilities of valence particle being outside the binding potential, which are 0.31±0.03 for the ⁸B ground state and 0.59±0.06 for the ¹¹Be first excited state. More than 50% probability outside the binding potential means that the ¹¹Be first excited state has a typical p-wave neutron halo. The rms radii are obtained to be 3.9±0.2 fm for the valence proton in the ⁸B ground state and to be 6.5±0.3 fm for the valence neutron in the ¹¹Be first excited state. The probabilities of the valence particle being in the non-classical region are extracted to be 0.41±0.04 and 0.46±0.05 for the ⁸B ground state and the ¹¹Be first excited state, respectively. The results demonstrate that although hindered by the effects of Coulomb and/or centrifugal barriers, their valence particle wavefunction still penetrates substantially into the classically forbidden region.

The fusion--evaporation reaction ¹¹⁶Sn (¹⁹F, p3n) ¹³¹Ce at projectile energy of 95 MeV is used to populate high spin states in ¹³¹Ce. The de-exciting γ-rays are detected in γ-γ coincidence measurement with Compton-suppressed BGO-HPGe detectors. Level lifetimes of ¹³¹Ce were determined by using the Doppler shift attenuation method. The experimental results indicate that collectivity of ¹³¹Ce is reduced relative to that of ¹³⁰Ce and it follows that deformation decreases with increase of the neutron number on the basis of systematic comparison of transition quadrupole moments for the light cerium isotopes.

We apply a statistical-evaporation model (HIVAP) to calculate the cross sections of superheavy elements, mainly in relation to actinide targets, and compare with some available experimental data. A reaction channel ³⁰Si + ²⁴³Am is proposed for the synthesis of the element Z = 109 and the cross section is estimated.

Using a nonperturbative scattering theory, we study the photoelectron angular distributions (PADs) of Kr atoms irradiated by an infinite sequence of intense single-cycle pulses of circular polarization. We demonstrate the inversion asymmetry of PADs and the dependence of PADs on the carrier-envelope phase of the single-cycle pulses. The inversion asymmetry is caused by the interference between transition channels where the different channels are characterized by different combinations of absorbed-photon numbers in the ionization process. Our results provide a possible method to determine the value of carrier-envelope phase by the detected PADs.

Differential cross sections for the elastic scattering of electrons by oxygen molecule are calculated for selected impact energies 7 eV and 9 eV. The results are compared with other theoretical results and experimental data. The present results are obtained by the momentum space optical potential method. This method take the polarization of target states into account, which is very important for the scattering problem, particularly at low energies.

A complex optical model potential correlated by the concept of bonded atom, which considers the overlapping effect of electron clouds between the two atoms in a molecule, is employed to calculate the total cross sections for electron scattering from the isoelectronic (Z = 14) molecules (C₂H₂, CO, HCN, and N₂) at 100-5000 eV using the additivity rule at the Hartree-Fock level. The difference between the bonded atom and the free one is that the overlapping effect of electron clouds of bonded atoms in molecules is considered. The quantitative molecular total cross section results are compared with the experimental data and with other calculations available and good agreement is obtained above 100 eV. It is shown that the additivity rule along with the complex optical model potential considering the overlapping effect of electron clouds can give results better than when uncorrelated by it. The correlating calculations are much closer to the experiments than the spherical-complex-optical-potential results in the lower energy region [Phys. Rev. A 45 (1992) 202]. Therefore, considering the overlapping effect of electron clouds in the complex optical potential could be helpful for the better accuracy of the total cross section calculations of electron scattering from molecules.

Absolute generalized oscillator strengths (GOSs) for the C 1 s preionization-edge transitions at 295.4 eV and 297.7 eV in perfluoroethane have been determined as functions of energy loss and momentum transfer (K) at impact energy of 2.5 keV for the first time. The corresponding GOS profiles have been found to have the characteristic dipole-dominated shapes with a strong maximum at K = 0. The spectral features can be interpreted in terms of transitions terminating at the σ^* (C-F) molecular orbital.

The interaction of an intense femtosecond laser field (～ 10¹⁶W/cm²) with argon clusters in a dense jet has been studied by measuring the energy and angle distributions of emitted ions. A directional anisotropy in the ion explosion energies is observed. The experimental results indicate that the average ion energies are up to 40% in the detection direction parallel to the laser polarization higher than that perpendicular to it. The measured ion yield increases about 80%, correspondingly. The findings are interpreted by charge-dependent ion acceleration and explosion of elliptic microplasma spheres.

It is reported that the Goos-Hänchen (GH) shift of both TE and TM light beams totally reflected from a dielectric interface can be greatly enhanced by a dielectric thin film without changing the property of total internal reflection. Numerical simulations confirm the theoretical analysis and show that the enhanced GH shift can be as large as the width of the beam for beam's width up to 820 times of the wavelength. This may stimulate investigations in other areas of physics and may lead to interesting applications in optical devices. The enhancement of the GH shift is accompanied by the enhancement of the intensity of the decaying field in the optically thin medium and of the propagating field inside the film.

We theoretically derive exact expressions for Mandel’s Q parameter of the triggered single molecular source, which is inferred from the probabilities P_RS(n) using the record of each photon detection event based on Hanbury Brown and Twiss detection. The real triggered source is recognized as an ideal single photon source with a Poissonian statistics background. How to decrease the background and to increase the efficiency are discussed. It is established that the sub-Poissonian statistics formation can be determined by comparing the measured Q_RS of the real single triggered molecular with Q_C of the Poissonian source containing the same mean photons. By this method, we also give an efficient way to measure signal-to-background ratios of triggered single photons.

We report the fabrication and the measurement of microcavities whose optical eigenmodes were discrete and were well predicted by using the model of the photonic dot with perfectly reflected sidewalls. These microcavities consisted of the semiconductor pillar fabricated by the simple wet-etched process and successive metal coating. Angle-resolved photoluminescence spectra demonstrate the characteristic emission of the corresponding eigenmodes, its pattern revealed by varying both polar (θ) and azimuthal (Ф) angles. It is shown that the metal-coated sidewalls can provide an efficient way to suppress the emission due to the leaking modes in these pillar microcavities.

We present a scheme for generation of an entangled state in many spatially separated bimodal cavity modes via cavity quantum
electrodynamics. A V-type three-level atom, initially prepared in a coherent superposition of its excited states, successively passes through both the bimodal cavities. If the atom is measured in its ground state after leaving the last cavity, an entangled state of many cavity modes can be generated. The conditions to generate the maximally entangled state with unity probability are worked out.

A simple actively mode-locked fibre ring laser is proposed and successfully demonstrated to generate switchable dual-wavelength picosecond pulses using a Bragg grating in a polarization-maintaining fibre. The wavelength spacing specified by the grating is only 0.52 nm. The proposed laser can be made to operate in stable dual-wavelength or switch between wavelengths at room temperature, only by simple adjustment of a polarization controller.

We present a simple calculation approach for the fundamental and second-harmonic sound beams with an arbitrary distribution source in the quasilinear approximation. The analysis is based on the assumption that the source function with an arbitrary geometry and distribution is expanded into the sum of a set of two-dimensional Gaussian functions. The two- and five-dimensional integral solutions for the fundamental and second-harmonic fields are, respectively, reduced in terms of Gaussian functions and simple one-dimensional integrals. The numerical evaluation of field distributions is then greatly simplified.

We investigate the influence of the initial laser phase on the interaction between relativistic electron and ultra-intense linear polarized laser field in a strong uniform magnetic field. It is found that the dynamic behaviour of the relativistic electron and the emission spectrum varies dramatically with different initial laser field phases. The effect of changing initial phase is contrary in the two parameter regions divided by the resonance condition. The phase dependence of the electron energy and velocity components are also studied. Some beat structure is found when the initial laser phase is zero and this structure is absent when the initial laser phase is a quarter of a period.

Using a one-dimensional slab model, we study the influence of the external static magnetic field on the anomalous skin effects in the inductively coupled plasma. The rf electromagnetic field in the plasma is determined by solving the linearized Boltzmann equation incorporating with the Maxwell equations. The numerical results show that, due to the existence of the external magnetic field, the anomalous skin effects are greatly enhanced and the number of regions with negative absorption is decreased.

We introduce gadolinium in chalcogenide glasses to exert unexpectedly the multiple magical effects on both optical and thermal mechanical properties of chalcogenide glasses. Notable increases in transition temperature T_g and microhardness H_v were observed due to structural densification and microcrystallization. Calculated molar volume values, differential scanning calorimetry and x-ray diffraction measurements provide supporting evidence. Gadolinium also acts as an oxygen getter by removing or weakening oxygen-related absorption bands, which is associated with the higher negative electrode potential.

We calculate the vibrational properties of potassium-doped single-walled carbon nanotubes within lattice dynamical theory. The results show that the frequency of high-frequency Raman mode E_2g for K₅C₄₀ downshifts to 1553 cm^-1, which is in agreement with the value for highly doped samples with effective composition KC₈. Moreover, the specific heat curves have a turnover at 22 K, originating from the saturation of K atoms vibrational modes at low energy.

Effects of SiO₂ encapsulation and rapid thermal annealing on the optical properties of a GaNAs/GaAs single quantum well (SQW) are studied by low-temperature photoluminescence (LTPL). After annealing at 800°C for 30 s, a blueshift of the LTPL peak energy for the SiO₂-capped region is 25 meV and that for the bare region is 0.8 meV. The results can be attributed to the nitrogen reorganization in the GaNAs/GaAs SQW. It is also shown that the nitrogen reorganization can be obviously enhanced by the SiO₂ cap-layer. A simple model is used to describe the SiO₂-enhanced blueshift of the LTPL peak energy. The estimated activation energy of the N atomic reorganization for the samples annealing with and without SiO₂ cap-layer are 2.9 eV and 3.1 eV, respectively.

The experimental relationship between width and amplitude of the non-destructive threshold pulse for Pt tip of a scanning tunnelling microscope (STM) on graphite surface have been studied strictly and systematically in a wide range of pulse width for the first time. The threshold curve of amplitude versus width indicates that the amplitude of threshold pulse will increase with the decrease of the pulse width. A more rigorous explanation is suggested to interpret the dependence of threshold pulse amplitude on width. Fitted with the experimental data, a new empirical formula is given, extrapolated from which the threshold pulse amplitude will rise to 50 V when the pulse width decreases to 10 ns.

The diffusion of N adatoms on a Ga-rich GaN(0001) surface has been studied using density-functional theory. The configuration of Ga adatoms on a Ga-rich GaN surface has been identified. The first adlayer Ga adatoms are on top of the terminating substrate Ga atoms, and the outmost adlayer Ga adatoms exist randomly at the T₄ or H₃ sites. A very different diffusivity of N adatoms on a Ga-rich GaN(0001) surface has been found. The excess Ga adatoms on a GaN(0001) surface reduce the diffusion barrier by 0.75 eV and influence the migration path. It seems that bilayer Ga adatoms are helpful for N atom diffusion.

We study the properties of exciton excitations in the Hubbard model with alternating potential and dimerized hopping terms at half-filling. With increasing Coulomb repulsion, we find that a spin triplet exciton band develops below the band gap. At certain critical interaction, the excitation gap of this exciton band vanishes and a new phase with a dimerized ground state emerges. The value of this critical Coulomb interaction is determined perturbatively.

We report the white organic-light devices (WOLEDs) employing a multiple quantum-well (MQW) structure, which consist of alternate layers of 4,48-bis(2,28-diphenylvinyl)-1,18-biphenyl (DPVBi) and (DPVBi:rubrene) as the potential barrier and the potential well, respectively. The results demonstrate that the MQW structure can prominently increase the performance of WOLEDs; the double quantum well device exhibits the efficiency up to 5.4 cd/A, and yields a peak luminance of 14206 cd/m². It is also interesting to find that the MQW structure can enhance the colour stability of WOLEDs at different voltages.

A long range interacting quantum spin chain with open boundary conditions is proposed. By constructing the reflection spin-Dunkl operators, the integrability of the model is proven. The model is therefore exactly solvable via the asymptotic Bethe ansatz method and falls into the universal class of the usual Heisenberg spin chain with boundary fields.

The effects of Al and Fe ion doping in Mn sites was studied for the colossal La_0.67Ca_0.33MnO₃ magnetoresistance material. It was found that when the Fe-doping amount x increases, the crystal cell structure has no obvious change, but the crystal cell volume decrease monotonically for Al-doping. Both resistances increase rapidly and the insulator-metal transition temperature moves to lower temperature and decreases linearly with Al-doping. The area for Al-doping is broader than Fe. At small amount of Al-doping, the resistance satisfy the metal transport property when T < T_IM. The characteristic of the transport behaviour for Al- and Fe-doping can be explained by terminating the double exchange channel of Mn³⁺-O^2--Mn⁴⁺.

Thin films of Nd³⁺-substituted Bi_3.15Nd_0.85Ti₃O₁₂ (BNT) were fabricated on the (111 Pt/TiO₂/SiO₂/Si substrates by a metalorganic deposition (MOD) technique. These thin films are possessed of a single-phase bismuth-layered structure showing the preferred (001) and (117) orientation. The values of the remanent polarization P_r and coercive field E_c of the BNT thin film are 27μC/cm² and 157 kV/cm, respectively. The results of fatigue and retention tests revealed that the BNT thin film was not fatigued up to 1.44 x 10¹⁰ switching cycles and the retained charge was unchanged after 1 x 10⁵s. The leakage current behaviour of the BNT thin film was investigated at room temperature and their conduction mechanisms were also discussed. The I-V characteristics of the film show the ohmic behaviour for applied field lower than 40 kV/cm. Nonlinearity in the I-V behaviour was observed at an applied field above 40 kV/cm. In the high field region (E > 95 kV/cm) the sample shows Schottky emission.

Photoluminescence (PL) spectra of the GaInNAs/GaAs single quantum well (SQW) with different N compositions are carefully studied in a range of temperatures and excitation power densities. The anomalous S-shape temperature dependence of the PL peak is analysed based on the competition and switching-over between the peaks related to N-induced localized states and the peak related to interband excitonic recombination. It is found that with increasing N composition, the localized energy increases and the turning point of the S-shape temperature dependence occurs at higher temperature, where the localized carriers in the band tail states obtain enough thermal activation energy to be dissociated and delocalized. The rapid thermal annealing (RTA) effectively reduces the localized energy and causes a decrease of the switching-over temperature.

Based on our previous study [Chin. Phys. Lett. 20 (2003) 1144] on the solid state cathodoluminescence from organic luminescent materials, here we study the origin and characteristics of blue light emission in solid state cathodoluminescence of Poly [(2-methoxy-5-(2'-ethyl-hexyloxy)phenylene vinyene] (MEH-PPV) and the dependence of each spectral peak on electric field strength. The results demonstrate that the blue spectral shift benefits from field ionization of excitons, and three regions of electric field are found, in which there are pure exciton emission, coexistence of exciton emission and radiative recombination, and pure radiative recombination.

We present red double-quantum-well organic light-emitting devices (DQW-OLEDs), in which N,N-bis-(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyo-4,4'-diamine (NPB) is used as potential barriers and hole transport layer, 4-(dicyanome-thylene)-2-t-butyl-6-(1,1,7,7-thtramethyljulolidyl-9-enyl)-4H-pyran (DCJTB) doped tris (8-hydroxyquinoline) aluminium (Alq₃) as potential wells and emitter, undoped Alq₃ as electron transport layer, respectively. The turn-on voltage is about 4 V. The maximum brightness and electroluminescent (EL) efficiency of the DQW device can reach 5916 cd m^-2 at 16 V and 2.85 cd A^-1 at 7 V, respectively. In addition, the EL efficiency of the DQW device is relatively independent of the drive voltage in the range from 5 V to 16 V.

Aqueous solutions containing a high yield of suspended gold nanorods with mean aspect ratio 2.5 have been synthesized via an electrochemical method. The fluorescence emission peaks fixed at 370 nm and 670 nm are due to the local field enhancement via coupling to the transverse and longitudinal surface plasmon resonance. The quasi-static calculation results indicate that with the increasing aspect ratio of the nanorods, the longer wavelength emission peak decreases and red shifts, whereas the shorter wavelength emission peak blue shifts slightly.

The emission yields of H, H₂, H₃ and heavy ions from carbon nanotubes under bombardments of Si and Si₂ clusters in an energy range of 0.3-3 MeV per atom are measured by using the time-of-flight technique (TOF). The emission yields of the secondary ions increase with increasing energy of Si and the electronic stopping processes play an important role. The enhanced emission yields of secondary ions induced by Si₂ clusters at the low energies are clearly seen and attributed to the vicinage effect of the nuclear collision processes of cluster constituents and the secondary ion emissions are still dominated by electronic stopping processes at high energies.

Boron nitride (BN) thin films with cubic boron nitride (c-BN) phase were prepared on the (100)-oriented surface of n-Si (0.008-0.02Ωm) by rf magnetron sputtering physical vapour deposition. The c-BN content is determined to be around 50% by using Fourier transform infrared spectroscopy for the BN thin films. The field emission characteristics of BN films were measured in an ultrahigh vacuum system. It is found that the field emission of the BN film with c-BN phase is evidently more excellent than that without c-BN phase. A turn-on field of 5 V/μm and a current of 460μA/cm² were obtained for the BN film with c-BN phase. The Fowler-Nordheim plots of emission characteristics of BN films indicate a straight line, which suggests the presence of the FN tunnelling.

Using the first-principle molecular dynamics simulations, we have studied the molecular geometrical configurations as well as the corresponding electronic structures of a single molecule device assembled by the mechanically controllable break junction technique with variations of the electrode distance. There are some very interesting features varying with the electrode distance.

We investigate the wave dispersion and attenuation in partially water-saturated sandstones based on the improved Biot/squirt (BISQ) model in which the saturation is introduced. Numerical experiments indicate that the phase velocity of the fast P-wave decreases as the saturation increases in the low-frequency range (10²-10⁴ Hz), and reaches the minimum at the full-saturation state. The behaviour of the phase velocity varying with the saturation in the high-frequency range (10⁴-10⁶ Hz), however, is opposite to that in the low-frequency range. The peak value of P-wave attenuation increases with increasing saturation, and is the maximum at the fully saturated state. Numerical models and experiments show that the improved BISQ model is better than the traditional Gassmann-Biot model.

Aimed at limitation and deficiency of the traditional Eliassen-Palm (EP) flux associated with wave-meanflow interaction and its subsequent generalization based on the Boussinesq approximation or quasi-geostrophic approximation, we develop an ageostrophic generalized E-P flux in baroclinic stratified atmosphere. This generalized E-P flux can be conveniently used to diagnose and analyse some important phenomena related to wave-meanflow interaction of the baroclinic atmosphere with observational data, such as the upper-level jet acceleration, gravity wave breaking-up and stratospheric erupt warming.

We show that the Newtonian forms for the motion of particles in mechanics and for light in geometrical optics can be extend to the Gibbons-Meada and the Garfinkle-Horne dilaton spacetimes in string theory. As an example, we study the bending of the light rays, the perihelion advance of a planet, and the radar echo delay in the dilaton spacetimes. The results show that the gravitational effects arising from the dilaton can be observed provided that the dilaton is large enough.

Using the new model of anomalous viscosity, we investigate the magnetic instability in the accretion discs and give the dispersion formula. On the basis of the dispersion relation obtained, it is numerically shown that the instability condition of the viscous accretion disc is well consistent with that of the ideal accretion disc, namely there would be magneto-rotational instability in the presence of a vertical weak magnetic field. For a given distance R from the centre of the disc, the growth rate in the anomalous case deviates from the ideal case more greatly when the vertical magnetic field is smaller. The large viscosity limits the instability. In the two cases, the distributions of growth rate with wavenumber k approach each other when the magnetic field increases. It greatly represses the effect of viscosity.

Within the current framework of disc galaxy formation, we discuss the resulted surface-density profiles according to the theoretical angular momentum distributions (AMDs) presented by Bullock et al. [Astrophys. J. 555 ,(2001) 240(B01)] for the Λ CDM cosmology in both spherical and cylindrical coordinates. It is found that the derived surface density distribution of a disc in the outer region is in general similar to an exponential disc for both the theoretical AMDs. In the central region, the results from both the theoretical AMDs are inconsistent with observations whether the disc bar-instability is taken into account or not. The cylindrical form of the theoretical AMD leads to the bar-instability more easily for a galaxy than that for spherical AMD, which could result in a more massive bulge. After comparing the model predictions with our Milky Way Galaxy, we find that the theoretical AMDs predict larger mass fractions of baryons with low angular momentum than the observed ones, which would lead to the disc sizes being smaller. Two possible processes which could solve the angular momentum problem are discussed.

We propose an analytical inflation model driven by a scalar field with Born-Infeld-type Lagrangian and compute its power spectrum. The constraints on the parameters of the potential by the recent Wilkinson microwave anisotropy probe data are derived.