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As a result of a systematic study on laser-induced forward transfer of tungsten (W) thin films by a focused Ar+ laser (λ=514 nm, 2w0=3μm), it is shown that deposition of 2–3μm diameter W spots of 100 nm thickness and 100% coverage is attainable at low processing powers (50–100 mW).

We present the first representation of the general term of the Rayleigh-Schr\"odinger series for quasidegenerate systems. Each term of the series is represented by a tree and there is a straightforward relation between the tree and the analytical expression of the corresponding term. The combinatorial and graphical techniques used in the proof of the series expansion allow us to derive various resummation formulas of the series. The relation with several combinatorial objects used for special cases (degenerate or non-degenerate systems) is established., Comment: 16 pages, 3 figures

Epigenetic modifications of the herpesviral genome play a key role in the transcriptional control of latent and lytic genes during a productive viral lifecycle. In this study, we describe for the first time a comprehensive genome-wide ChIP-on-Chip analysis of the chromatin associated with the Kaposi's sarcoma-associated herpesvirus (KSHV) genome during latency and lytic reactivation. Depending on the gene expression class, different combinations of activating [acetylated H3 (AcH3) and H3K4me3] and repressive [H3K9me3 and H3K27me3] histone modifications are associated with the viral latent genome, which changes upon reactivation in a manner that is correlated with their expression. Specifically, both the activating marks co-localize on the KSHV latent genome, as do the repressive marks. However, the activating and repressive histone modifications are mutually exclusive of each other on the bulk of the latent KSHV genome. The genomic region encoding the IE genes ORF50 and ORF48 possesses the features of a bivalent chromatin structure characterized by the concomitant presence of the activating H3K4me3 and the repressive H3K27me3 marks during latency, which rapidly changes upon reactivation with increasing AcH3 and H3K4me3 marks and decreasing H3K27me3. Furthermore, EZH2, the H3K27me3 histone methyltransferase of the Polycomb group proteins (PcG), colocalizes with the H3K27me3 mark on the entire KSHV genome during latency, whereas RTA-mediated reactivation induces EZH2 dissociation from the genomic regions encoding IE and E genes concurrent with decreasing H3K27me3 level and increasing IE/E lytic gene expression. Moreover, either the inhibition of EZH2 expression by a small molecule inhibitor DZNep and RNAi knockdown, or the expression of H3K27me3-specific histone demethylases apparently induced the KSHV lytic gene expression cascade. These data indicate that histone modifications associated with the KSHV latent genome are involved in the regulation of latency and ultimately in the control of the temporal and sequential expression of the lytic gene cascade. In addition, the PcG proteins play a critical role in the control of KSHV latency by maintaining a reversible heterochromatin on the KSHV lytic genes. Thus, the regulation of the spatial and temporal association of the PcG proteins with the KSHV genome may be crucial for propagating the KSHV lifecycle., Author Summary KSHV is a ubiquitous herpesvirus that establishes a life-long persistent infection in humans and is associated with Kaposi's sarcoma and several lymphoid malignancies. During latency, the KSHV genome persists as a multicopy circular DNA assembled into nucleosomal structures. While viral latency is characterized by restricted viral gene expression, reactivation induces the lytic replication program and the expression of viral genes in defined sequential and temporal order. Posttranslational modifications of the viral chromatin structure have been implicated to regulate viral gene expressions but the underlying gene regulatory mechanisms are still elusive. Here, we demonstrate that the latent and lytic chromatins of KSHV are associated with a distinctive pattern of activating and repressive histone modifications whose distribution changes upon reactivation in an organized manner in correlation with the temporally ordered expression of viral lytic genes. Furthermore, we demonstrate that the evolutionarily conserved Polycomb group proteins, that maintain the repression of genes involved in hematopoiesis, X-chromosome inactivation, cell proliferation and stem cell differentiation, also play a critical role in the regulation of KSHV latency by maintaining a repressive chromatin structure. Thus, the epigenetic program of KSHV is at the crux of restricting latent gene expression and the orderly expression of lytic genes.

Motivated by various results on homogeneous geodesics of Riemannian spaces, we study homogeneous trajectories, i.e. trajectories which are orbits of a one-parameter symmetry group, of Lagrangian and Hamiltonian systems. We present criteria under which an orbit of a one-parameter subgroup of a symmetry group G is a solution of the Euler-Lagrange or Hamiltonian equations. In particular, we generalize the `geodesic lemma' known in Riemannian geometry to Lagrangian and Hamiltonian systems. We present results on the existence of homogeneous trajectories of Lagrangian systems. We study Hamiltonian and Lagrangian g.o. spaces, i.e. homogeneous spaces G/H with G-invariant Lagrangian or Hamiltonian functions on which every solution of the equations of motion is homogeneous. We show that the Hamiltonian g.o. spaces are related to the functions that are invariant under the coadjoint action of G. Riemannian g.o. spaces thus correspond to special Ad*(G)-invariant functions. An Ad*(G)-invariant function that is related to a g.o. space also serves as a potential for the mapping called `geodesic graph'. As illustration we discuss the Riemannian g.o. metrics on SU(3)/SU(2)., v3: some misprints corrected

A comparative study on metal pattern deposition of mm2-area by ablating chromium and titanium thin films from an optically transparent support and transferring the ablated material onto another substrate in close proximity with a single laser pulse (LIFT) is reported. The role of support-film interface and film-to-substrate distance in determining both ablation and transfer is discussed. The sequence of events as a function of processing fluence is interpreted by comparing experimental data with calculated temperature distributions. In the case of poorly adhering films the transfer yield is independent of film-to-substrate distance between 0 and 60 μm throughout the fluence range studied. The transmittance of the ablated areas of well adhering films decreases and that of the corresponding prints increases with increasing distance as evaporation becomes dominant.

The problem of extending quantum-mechanical formal scattering theory to a more general class of models that also includes quantum field theories is discussed, with the aim of clarifying certain aspects of the definition of scattering states. As the strong limit is not suitable for the definition of scattering states in quantum field theory, some other limiting procedure is needed. Two possibilities are considered, the abelian limit and adiabatic switching. Formulas for the scattering states based on both methods are discussed, and it is found that generally there are significant differences between the two approaches. As an illustration of the application and the features of these formulas, S-matrix elements and energy corrections in two quantum field theoretical models are calculated using (generalized) old-fashioned perturbation theory. The two methods are found to give equivalent results., Comment: 20 pages

A simple modification of the definition of the S-matrix is proposed. It is expected that the divergences related to nonzero self-energies are considerably milder with the modified definition than with the usual one. This conjecture is verified in a few examples using perturbation theory. The proposed formula is written in terms of the total Hamiltonian operator and a free Hamiltonian operator and is therefore applicable in any case when these Hamiltonian operators are known., Comment: 24 pages, 1 figure; v2: revised version; v3: section 3 improved. Accepted for publication in Central European Journal of Physics; v4: minor text misprints corrected

The UL69 protein of human cytomegalovirus is a multifunctional regulatory protein that has counterparts in all herpesviruses. Some of these proteins have been shown to function primarily at the post-transcriptional level in promoting nuclear export of viral transcripts. Consistently, this group has reported recently that pUL69 is an RNA-binding, nucleocytoplasmic shuttling protein that facilitates the cytoplasmic accumulation of unspliced mRNA via its interaction with the cellular mRNA export factor UAP56. Evidence has been presented to suggest that some of the pUL69 homologues self-interact and function in vivo as multimers. Herein, the possibility of pUL69 self-association was examined and it has been demonstrated that pUL69 can interact with itself in vitro and in vivo in order to form high-molecular-mass complexes. The self-interaction domain within pUL69 was mapped to a central domain of this viral protein that is conserved within the homologous proteins of other herpesviruses, suggesting that multimerization is a conserved feature of this protein family.

Proton Beam Writing has been successfully used to create buried channel waveguides in PMMA, which suggested that proton irradiation increases the refractive index. To investigate this effect, PMMA samples were irradiated by 1.7–2.1 MeV proton beam. Spectroscopic ellipsometry has been used to investigate the depth profile of the refractive index. An increase of the refractive index was observed in the order of 0.01, which is approximately one order of magnitude higher than the detection limit. The highest increase of the refractive index occurs at the end of range, i.e. we found a good correlation with the Bragg curve of the energy loss.

We investigate the idea that the effect of the truncation applied in the TCSA method on the spectrum coincides with the effect of a suitable changing of the coefficients of the terms in the Hamiltonian operator. The investigation is done in the case of the critical Ising model on a strip with an external magnetic field on one of the boundaries. A detailed quantum field theoretical description of this model is also given, and we propose a description as a perturbation of the infinite coupling limit. The investigation is also carried out for a truncation method which preserves the solvability of the model. The results of perturbative and numerical calculations presented support the above idea and show that the qualitative behaviour of the truncated spectrum as a function of the coupling constant depends on the truncation method., 39 pages

The UL69 gene product of human cytomegalovirus belongs to a family of regulatory proteins conserved among all herpesviruses that have in part been characterized as posttranscriptional transactivators participating in the nuclear export of RNA. Recent experiments suggested that pUL69 also acts as a posttranscriptional activator since it was demonstrated that nucleocytoplasmic shuttling via a CRM1-independent nuclear export signal is a prerequisite for its stimulatory effect on gene expression. Based on these findings we initiated studies to investigate the role of pUL69 in mRNA export and demonstrate that pUL69 efficiently promotes the cytoplasmic accumulation of unspliced RNA. Furthermore, we show that this pUL69 activity is linked to the cellular mRNA export machinery by direct protein interaction with the highly related DEXD/H-box RNA helicases UAP56 and URH49. Particularly, we identified a 12-amino-acid domain within the N terminus of pUL69 which is required for binding to UAP56 and URH49, and we could demonstrate that UAP56 interaction and nucleocytoplasmic shuttling are both prerequisites for pUL69-mediated mRNA export. Thus, we identified a novel cellular target which provides a herpesviral regulatory protein with access to a conserved cellular transport system in order to promote nuclear export of unspliced RNA.

The human cytomegalovirus protein pUL69 belongs to a family of regulatory factors that is conserved within the Herpesviridae and includes the proteins ICP27 of herpes simplex virus type 1 and EB2 of Epstein-Barr virus. ICP27 and EB2 have been shown to facilitate the nuclear export of viral mRNAs via interacting with the cellular mRNA export factor REF. Furthermore, direct RNA-binding of these proteins was found to be essential for their stimulating effects on mRNA export. Recently, we demonstrated that pUL69 shares common features with ICP27 and EB2 such as (i) nucleocytoplasmic shuttling and (ii) stimulation of nuclear RNA export via binding to the cellular mRNA export machinery. Here, we demonstrate that pUL69 can also interact with RNA both in vivo and in vitro via a complex N-terminal RNA-binding domain consisting of three arginine-rich motifs. Interestingly, the RNA-binding domain of pUL69 overlaps with both the NLS and the binding site of the cellular mRNA export factors UAP56 and URH49. While the deletion of the UAP56/URH49-binding site abolished pUL69-mediated RNA export, an RNA-binding deficient pUL69 mutant which still interacts with UAP56/URH49 retained its RNA export activity. This surprising finding suggests that, in contrast to its homologues, RNA-binding is not a prerequisite for pUL69-mediated nuclear RNA export.

The phytohormone abscisic acid (ABA) regulates essential growth and developmental processes in plants. Recently, RNA-binding proteins have been described as components of ABA signaling during germination. We have identified ten ABA-regulated RNA-binding proteins in Arabidopsis seedlings. Among those genes, AtCSP41B and cpRNP29 are highly expressed in seedlings. Using promoter:reporter gene analyses, we showed that both AtCSP41B and cpRNP29 were in particular expressed in photosynthetically active organs like green cotyledons, leaves, and petioles. The analysis of CFP-fusion proteins demonstrates that cpRNP29 localized to chloroplasts and AtCSP41B to chloroplasts and stromules. Whereas RNA-binding of cpRNP29 has previously been shown, we demonstrated through in vitro RNA-binding assays that recombinant AtCSP41B binds to RNA, and that chloroplast petD RNA can serve as a target of AtCSP41B. Developmental or environmental stimuli affected the expression of AtCSP41B and cpRNP29 in seedlings. Both genes were repressed during senescence, but only AtCSP41B was significantly repressed upon water stress. In addition, AtCSP41B and cpRNP29 exhibited low expression in etiolated seedlings compared to green seedlings, and cpRNP29 was regulated during the day photoperiod. Homozygous T-DNA insertion lines were isolated, characterized on the molecular level, and monitored for phenotypic changes. Taken together, the data show that both proteins are regulated during processes that are known to involve ABA signaling. Their localization in chloroplasts and RNA-binding activity suggest a role in chloroplast RNA metabolism in Arabidopsis seedlings.

A new weight-drop head-injury apparatus is described that can produce a momentary depression of predetermined depth at a predetermined site of the elastic calvaria of scalped young adult rats. In Wistar rats weighing about 200 g, a 0.75-mm deep calvaria depression immediately caused ultrastructural (neurofilament) compaction in many long axon segments, which were diffusely scattered among non-compacted axons in a well-defined area of cortical layers IV and V under the impact site. Apart from these morphological changes and swollen astrocytic processes in their vicinity, the brain tissue appeared non-impaired. The blood pressure, intracranial pressure, heart rate and respiration rate had returned to the normal range in 1 min. Diffuse axonal swelling caused by impaired axonal transport, ultrastructural compaction in neuronal soma-dendrite domains, impression fracture and subarachnoid or subdural hemorrhages were observed only in rats with a calvaria depression of 1 mm or more. All these features create favorable circumstances for study of various problems that are closely related to the ultrastructural (neurofilament) compaction in axons, such as the fate of the affected axons.

We investigate the behavior of ${}^{85}\mathrm{Rb}$ atoms in the field of a sequence of frequency-chirped short laser pulses. The analysis is based on a numerical solution of equations for the probability amplitudes of the hyperfine levels of the ${5S}_{1/2}{\ensuremath{-}5P}_{3/2}$ transition in the ${}^{85}\mathrm{Rb}$ atom and the dressed-states analysis. We analyze different regimes of interaction, including relatively short laser pulses (when the width of the pulse envelope spectrum is of the order of or exceeds the frequency interval between the hyperfine levels resulting in effective mixing of them) and relatively long ones (when the ground hyperfine levels are resolved but the excited ones are not resolved). In the latter case dependence of the population transfer efficiency on the initial coherence of the ground states is analyzed. The case of long laser pulses when all working hyperfine levels are resolved is also discussed using numerical simulations and a dressed-states analysis. We show that in all regimes considered, the interaction of a frequency-chirped laser pulse with the multilevel ${}^{85}\mathrm{Rb}$ system is similar to the interaction with an effective two-level atom at sufficiently large peak intensities of the pulses. It allows us to perform efficient excitation of the multilevel atom by transferring populations of two hyperfine ground states to the excited ones and back to the ground states using a pair of frequency-chirped laser pulses. We propose to utilize this scheme of population transfer for the coherent manipulation of a beam of ${}^{85}\mathrm{Rb}$ atoms using sequences of counterpropagating frequency-chirped short laser pulses.

We investigate the boundary bootstrap programme for finding exact reflection matrices of integrable boundary quantum field theories with N=1 boundary supersymmetry. The bulk S-matrix and the reflection matrix are assumed to take the form S=S_1S_0, R=R_1R_0, where S_0 and R_0 are the S-matrix and reflection matrix of some integrable non-supersymmetric boundary theory that is assumed to be known, and S_1 and R_1 describe the mixing of supersymmetric indices. Under the assumption that the bulk particles transform in the kink and boson/fermion representations and the ground state is a singlet we present rules by which the supersymmetry representations and reflection factors for excited boundary bound states can be determined. We apply these rules to the boundary sine-Gordon model, to the boundary a_2^(1) and a_4^(1) affine Toda field theories, to the boundary sinh-Gordon model and to the free particle., 43 pages, LaTex, 14 eps figures, minor corrections

A simple single‐step technique for surface patterning is presented. It is shown that well‐adhering micrometer‐sized patterns of 100% coverage preserving the shape and dimensions of the ablated area can be deposited by ablating and transferring tungsten thin films in the form of single solid pieces using single pulses of peak power up to 100 mW and 100 μs–1 ms duration from a diode‐pumped YAG laser.

Head injury is a causative factor in the development of temporal lobe epilepsy. However, whether a single episode of concussive head trauma causes a persistent increase in neuronal excitability in the limbic system has not been unequivocally determined. This study used the rodent fluid percussion injury (FPI) model, in combination with electrophysiological and histochemical techniques, to investigate the early (1 week) and long-term (1 month or longer) changes in the hippocampus after head trauma. Low-frequency, single-shock stimulation of the perforant path revealed an early granule cell hyperexcitability in head-injured animals that returned to control levels by 1 month. However, there was a persistent decrease in threshold to induction of seizure-like electrical activity in response to high-frequency tetanic stimulation in the hippocampus after head injury. Timm staining revealed both early- and long-term mossy fiber sprouting at low to moderate levels in the dentate gyrus of animals that experienced FPI. There was a long-lasting increase in the frequency of spontaneous inhibitory postsynaptic currents in dentate granule cells after FPI, and ionotropic glutamate receptor antagonists selectively decreased the spontaneous inhibitory postsynaptic current frequency in the head-injured animals. These results demonstrate that a single episode of experimental closed head trauma induces long-lasting alterations in the hippocampus. These persistent structural and functional alterations in inhibitory and excitatory circuits are likely to influence the development of hyperexcitable foci in posttraumatic limbic circuits.

1. Cytochemical and in vitro whole-cell patch clamp techniques were used to investigate granule cell hyperexcitability in the dentate gyrus 1 week after fluid percussion head trauma. 2. The percentage decrease in the number of hilar interneurones labelled with either GAD67 or parvalbumin mRNA probes following trauma was not different from the decrease in the total population of hilar cells, indicating no preferential survival of interneurones with respect to the non-GABAergic hilar cells, i.e. the mossy cells. 3. Dentate granule cells following trauma showed enhanced action potential discharges, and longer-lasting depolarizations, in response to perforant path stimulation, in the presence of the GABAA receptor antagonist bicuculline. 4. There was no post-traumatic alteration in the perforant path-evoked monosynaptic excitatory postsynaptic currents (EPSCs), or in the intrinsic properties of granule cells. However, after trauma, the monosynaptic EPSC was followed by late, polysynaptic EPSCs, which were not present in controls. 5. The late EPSCs in granule cells from fluid percussion-injured rats were not blocked by the NMDA receptor antagonist 2-amino-5-phosphonovaleric acid (APV), but were eliminated by both the non-NMDA glutamate receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) and the AMPA receptor antagonist GYKI 53655. 6. In addition, the late EPSCs were not present in low (0.5 mM) extracellular calcium, and they were also eliminated by the removal of the dentate hilus from the slice. 7. Mossy hilar cells in the traumatic dentate gyrus responded with significantly enhanced, prolonged trains of action potential discharges to perforant path stimulation. 8. These data indicate that surviving mossy cells play a crucial role in the hyperexcitable responses of the post-traumatic dentate gyrus.

The ablation of thin films by single laser pulse is a well known technique with widespread industrial applications. Ablation occurs in a well defined power density region if a supported thin film is illuminated by a single laser pulse. In the literature there are a number of theoretical description of ablation, but a very few based on in-situ experiments. In our study we have directly visualized the ablation processes with fast photography based on application of dye laser probe pulses. The ablation of chromium and tungsten layers supported onto glass substrates with pulses of ArF excimer laser was investigated. The ablated area was illuminated by a delayed short pulse of a fluorescein dye laser or a Rhodamine6G dye laser. Snapshots of initial phase of ablation and the forthcoming material transport were recorded by an optical system and a video camera. Blowing-off mechanisms and thermo-mechanical mechanisms are considered to take place during ablation. Pressures formed during laser ablation were calculated and compared with experimental data. It was found that thermo- desorption of gas adsorbed on to the substrate surface, substrate materials evaporation and film exfoliation by its longitudinal thermal enlargement may be acting during laser ablation of thin films.

An imaging system with nanosecond resolution was developed and used for investigation of excimer laser induced ablation. The photographic recordings were made by means of a videocamera equipped with a microscope. Dye laser pulses used for exposition were delayed appropriately with respect to the incidence of the excimer laser light. The movement of the plume ejected from the sample and the propagation of the mechanical waves developed in and above the sample were visualized. Using single recording pulses the distance-time functions were obtained. The velocity-time functions were calculated by derivation of those. Applying a Michelson interferometer for generating double exposing dye laser pulses with delay dt, the average velocity for dt could be measured directly. The propagation velocity of shock waves originating from the polymethyl-methacrylate surface was investigated by this technique in Schlieren arrangement. Velocities as high as 40 times the sound velocity in the air were measured. The material ablated from the polymethyl-methacrylate was observed in vacuum by single exposition transmission arrangement. During the excimer laser ablation of cornea several phenomena occur, such as shock wave in the air, shear wave on the surface, internal acoustic wave, plume ejection and so on. The characteristic velocities of these are shown. 7© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The application of laser pulses as `photographic flash' gives the possibility to record ultrafast phenomena. Since the duration of the laser pulses may be tuned from fs to cw, it is easy to choose a right laser source to resolve the time domain to be investigated. In this study excimer laser ablation of molten metal targets was followed by ultrafast photography based on delayed dye laser pulses. Molten tin and bismuth were ablated in vacuum by an ArF excimer laser. Pictures of the surface and the ablated material were taken at different moments after the start of the excimer laser pulse with temporal resolution of 1 ns. The series of snapshots contain information on the initial phase of plume formation in the ns time regime, and on liquid motion (surface waves, protuberances, liquid jet formations, splashing) in microsecond time scale. The important result of this study is the registration of the processes leading to droplet emission from the ablated target surface, because the elimination of droplets is a crucial requirement in depositing thin films by the pulsed laser deposition technique.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Combined thermally induced etching and deposition of W in a mixture of WF6 and H2 is investigated by local laser-induced patterning of thin tungsten layers on quartz. The process divides into areas of pure etching and deposition, depending on the partial pressures of the gases.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The time evolution of ablation and material transport during ArF excimer laser induced blow off of tungsten films from glass substrates is studied by fast photography using delayed dye laser pulses. The analysis of experimental results combined with heat flow calculations provides evidence that tungsten removal in the solid phase is the dominant mechanism in the 40 - 200 mJ/cm2 fluence domain, while partially inhomogeneous melting is observed between 200 and 800 mJ/cm2. In this fluence range, solid fragments and a halo consisting of molten droplets are observed indicating spatial separation of the two phases. The molten phase advances faster, forming a protective mist in front of the solid piece(s). At yet higher fluences (800 - 1000 mJ/cm2), a well separated solid phase could be recorded under the halo although model calculations suggest full vaporization of the layer. This unexpected phenomenon is explained by the optical shielding effect of the halo.

The measurements of ozone content, evaluation of UV radiation and their links with skin cancer in Hungary have been studied for the last three decades. The total ozone content of an air column above Hungary has been measured by the Hungarian Meteorological Service since 1969 using Dobson-spectrophotometer. The measurements of UV-B radiation started in 1993 by three Robertson-Berger equipments and LI-1800 spectroradiometer. It was found a decreasing trend of ozone content 1.7% per 10 years. Since 1991/92 winter the ozone conditions of the stratosphere have been perturbed. Such low ozone values that have been observed in two winters successively never occurred. Deficits in monthly averages: 1991 Dec: -6%, 1992 Jan; -17%, Feb; -9%, Dec; - 10%, 1993 Jan; -16%, Feb; -17%. Statistical analysis of the patient material of the Eastern region of Hungary, characterized by a rather high intensity of sunlight and UV rays, has shown a significant increase in light induced skin disorders in recent decades. Ninety-six photoallergic and phototoxic cases followed up in 1966 rose to 336 (1977) and 788 (1993) whereas the numbers of patients with basal cell carcinoma and malignant melanoma increased two- and fivefold, respectively, from 1966 to 1993. A UV personal dosimeter has been developed to measure exposure of the skin to UV-B radiation. These SUNTEST UV-sensitive strips for general public are produced by FORTE Photochemical Company.

A simple and inexpensive single-step technique for surface patterning in the micrometers regime is presented. As a result of a systematic study on laser-induced ablation and transfer of tungsten thin films it is shown that deposition of well adhering micrometer sized patterns of 100% coverage preserving the shape and dimensions of the laser processed area can be attained by single pulses of peak power up to 100 mW and 100 microsecond(s) - 1 ms duration from a diode laser pumped YAG laser.

The late-time behavior of a scalar field on fixed Kerr background is examined in a numerical framework incorporating the techniques of conformal compactification and hyperbolic initial value formulation. The applied code is 1+(1+2) as it is based on the use of the spectral method in the angular directions while in the time-radial section fourth order finite differencing, along with the method of lines, is applied. The evolution of various types of stationary and non-stationary pure multipole initial states are investigated. The asymptotic decay rates are determined not only in the domain of outer communication but along the event horizon and at future null infinity as well. The decay rates are found to be different for stationary and non-stationary initial data, and they also depend on the fall off properties of the initial data toward future null infinity. The energy and angular momentum transfers are found to show significantly different behavior in the initial phase of the time evolution. The quasinormal ringing phase and the tail phase are also investigated. In the tail phase, the decay exponents for the energy and angular momentum losses at future null infinity are found to be smaller than at the horizon which is in accordance with the behavior of the field itself and it means that at late times the energy and angular momentum falling into the black hole become negligible in comparison with the energy and angular momentum radiated toward future null infinity. The energy and angular momentum balances are used as additional verifications of the reliability of our numerical method., Comment: 33 pages, 12 figures

The three-state Potts field theory in two dimensions with thermal and magnetic perturbations provides the simplest model of confinement allowing for both mesons and baryons, as well as for an extended phase with deconfined quarks. We study numerically the evolution of the mass spectrum of this model over its whole parameter range, obtaining a pattern of confinement, particle decay and phase transitions which confirms recent predictions.

One of the characteristic features of herpesviruses is that most of their genes are intronless. Thus, their replication relies on the selective nuclear export of intronless viral mRNAs, which have to compete with the nuclear export of bulk spliced cellular mRNAs. Therefore, the regulation of nuclear mRNA export is crucial for the replication and pathogenesis of herpesviruses. Besides the thymidine kinase transcript of herpes simplex virus type 1, which contains specific sequences to facilitate the nuclear export of intronless mRNA, other cis-acting RNA elements for nuclear mRNA export have not yet been identified in the rest of herpesviral intronless mRNAs. Instead, emerging studies show that herpesviruses encode viral mRNA export factors, which interact with components of the major cellular mRNA export pathway, the RNA polymerase II transcription complex and specific splicing factors to selectively export intronless herpesviral mRNAs to the cytoplasm in infected cells. These herpesviral mRNA export factors are members of a conserved gene family that can be found in all herpesviruses. The human cytomegalovirus transactivator protein UL69, which has been demonstrated to belong to this conserved protein family, shares common features with its herpesviral homologues but also possesses unique properties that will be discussed in this review.

Besults of a systematic study on Q-switched nthy laser induced rrrn2 area transfer of supported titanium and chranium thin films and Ge/Se multilayer structures are reported. The appearance of the prints is governed by film-support adhesion and source-target spacing. Best quality prints are produced by ablating well adhering ntal films in close proximity ( spacing < 15 pm) to the target to be patterned. Transfer fran stacked elenntaxy layers as a source offers a unique possibility of depositing acinpound films by mixing the constituents and transferring the material onto the target substrate in a single step.© (1990) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Diamondlike properties of amorphous carbon films can be enhanced by applying reactive hydrogen atmosphere during pulsed laser deposition (PLD) as shown by recent studies. The complex phenomena occurring during carbon plume expansion has not been examined yet thoroughly. Therefore we deposited amorphous hydrogenated carbon thin films in hydrogen ambient atmosphere (4×10−4–25Pa) by PLD at room temperature. The deposited films were characterized by Rutherford backscattering spectrometry, elastic recoil detection analysis, Raman spectroscopy, infrared spectroscopy, variable angle spectroscopic ellipsometry, and nanoindentation measurements. At low hydrogen pressures (below ∼0.1Pa), when the mean free path of plasma constituents in the background gas is larger than the target substrate distance, the deposited films show diamondlike properties. At higher pressures (above ∼0.1Pa) the deposited films change their diamondlike carbon character towards to a structure which contains increasing amount of sp2 bonded ca...

The adsorption and dissociation of methanol on clean and K-dosed Pd(100) surfaces were investigated in the temperature range 90–600 K. By means of photoelectron and thermal desorption spectroscopy, condensed layer, chemisorbed and dissociated methanol were distinguished. Methanol decomposes through the formation of a methoxy species. No adsorbed CH3 was detected on clean Pd(100) in the course of heating of the adsorbed layer from 90 K to high temperatures. The cleavage of a methanolic CO bond, and the formation of a small amount of adsorbed CH3 were observed only above 300 K, but during continuous dosing of the surface with CH3OH. Additive potassium markedly increased the surface concentration of chemisorbed methanol and the formation of methoxy species, but it did not enhance the methanolic C-O bond breaking. A significant stabilization of methoxy was also experienced: its complete decomposition occurred at 450–500 K. In the discussion of the data, a direct chemical interaction between methanol and potassium and the formation of a stable KOCH3 complex are proposed.

Grammar induction is an important and current area within computational linguistics. The results in induction of string transformation rules can be applied not only in linguistics but in many other pattern recognition tasks. The task of grammar induction belongs in general to NP -hard problems. The paper analyses the main rule types in natural languages and in string transformation systems. The paper focuses on the inference of inflectional rule systems which differs in many aspects from the traditional production rule system of Chomsky grammars. The work compares the main candidate methods on the learning of objective-case in the Hungarian language.