Assessment of the function of the lower limb and gait of patients after knee replacement using physical therapy

Purpose. To study the dynamics of the function of the lower limb and gait of patients after knee replacement using physical therapy. Material & Methods. Patients were randomly distributed into groups – control (CG) and study (MG), each group – 12 people (n=24). The groups received a rehabilitation intervention according to the International Classification of Functioning, Disability and Health (ICF) concept. For each person, a categorical profile was created and SMART goals were set. The developed program of physical therapy (PT) for the MG, taking into account short-term goals in a SMART format, included the use of kinesitherapy according to the author’s method, hydrokinesitherapy and physiotherapy. Lower limb function and gait were assessed before and after the intervention using the Visual Analogue Pain Scale (VAS), goniometry, Tegner-Lusholm scale and Timed Up and Go (TUG) Test. Results. VAS pain scores showed significant dynamics in both groups, but without a significant difference between the groups (p>0,05). Indicators of the amplitude of flexion in the operated knee joint approached the normative values; in patients from the MG they improved by 23,51%, and in the CG – by 10,83% (p<0,05). Improvement in indicators on the Tegner-Lusholm scale after the rehabilitation cycle occurred in both groups (p<0,05), but the results of the MG were significantly higher (p<0.05). During the repeated study, 16.66% of the CG showed an "excellent result", in the absence of such a result in the CG. Timed Up and Go (TUG) Test indicators had positive dynamics in both groups (p<0,05), but large changes were observed in the MG (р<0,05). Conclusions. analysis of the dynamics of indicators of physical functions, range of motion and gait of persons 50-64 years old after total knee replacement confirmed the advantages of the developed physical therapy program for persons in the MG.

Investigating charge-up and fragmentation dynamics of oxygen molecules after interaction with strong X-ray free-electron laser pulses

The X-ray-induced charge-up and fragmentation process of a small molecule is examined in great detail by measuring the molecular-frame photoelectron interference pattern in conjunction with other observables in coincidence.

Pulse Energy and Pulse Duration Effects in the Ionization and Fragmentation of Iodomethane by Ultraintense Hard X Rays

The interaction of intense femtosecond x-ray pulses with molecules sensitively depends on the interplay between multiple photoabsorptions, Auger decay, charge rearrangement, and nuclear motion. Here, we report on a combined experimental and theoretical study of the ionization and fragmentation of iodomethane (CH_{3}I) by ultraintense (∼10^{19}  W/cm^{2}) x-ray pulses at 8.3 keV, demonstrating how these dynamics depend on the x-ray pulse energy and duration. We show that the timing of multiple ionization steps leading to a particular reaction product and, thus, the product's final kinetic energy, is determined by the pulse duration rather than the pulse energy or intensity. While the overall degree of ionization is mainly defined by the pulse energy, our measurement reveals that the yield of the fragments with the highest charge states is enhanced for short pulse durations, in contrast to earlier observations for atoms and small molecules in the soft x-ray domain. We attribute this effect to a decreased charge transfer efficiency at larger internuclear separations, which are reached during longer pulses.

Immune-inflammatory concept of the pathogenesis of chronic heart failure in dogs with dilated cardiomyopathy

Background:

Dilated cardiomyopathy is common in dogs. This form of cardiomyopathy is the main cause of death due to heart disease in dogs. Death can occur suddenly in clinically normal animals as a result of the progression of congestive heart failure (CHF). The pathogenesis of heart failure syndrome in dogs with dilated cardiomyopathy involves activation of the neurohumoral system and immune-mediated inflammation, which leads to further progression of the condition. Heart failure syndrome in dogs with dilated cardiomyopathy is caused by the progressive loss of cardiomyocytes, apoptosis, remodeling of the left ventricle, systolic and diastolic dysfunction, arrhythmias, reduced cerebral blood flow, the involvement of other key internal organs, and intestinal dysbiosis.

Aim:

This study aimed to determine the immunological and inflammatory mechanisms surrounding the development of heart failure syndrome in dogs with dilated cardiomyopathy.

Materials and Methods:

The subjects of this study were dogs with a dilated form of cardiomyopathy (n=159), complicated by various functional classes of heart failure syndrome. Evaluation of myocardial remodeling, systolic function, and systemic hemodynamics was performed using EMP-860 Vet and PU-2200V ultrasound scanners according to the standard technique. Electrocardiography was performed with all dogs in right lateral recumbency using the EK1T-04 Midas electrocardiograph (50 mm/s speed and 1 mV gain = 1 cm).

Results:

In some affected animals, especially in cases of compensated dilated cardiomyopathy, leukocytosis was noted. In patients with dilated cardiomyopathy complicated by heart failure syndrome of various functional classes, the number of neutrophils was significantly increased, and the number of lymphocytes was decreased by 1.9-2.1 times when compared with those in clinically normal animals. In dogs with dilated cardiomyopathy, neutrophilic leukocytosis develops with a simple regenerative shift to the left. The results of immunological studies indicate that dogs with dilated cardiomyopathy develop T lymphocytopenia as compared with clinically normal animals.

Conclusion:

The central component of heart failure syndrome in dogs with dilated cardiomyopathy is the activation of the neurohumoral system and immune-mediated inflammation. The development of CHF in dogs with dilated cardiomyopathy is caused by the progressive loss of cardiomyocytes, apoptosis, remodeling of the left ventricle, systolic and diastolic dysfunction, arrhythmias, reduced cerebral blood flow, involvement of other key internal organs, and intestinal dysbiosis.

Evidence of Extreme Ultraviolet Superfluorescence in Xenon

We present a comprehensive experimental and theoretical study on superfluorescence in the extreme ultraviolet wavelength regime. Focusing a free-electron laser pulse in a cell filled with Xe gas, the medium is quasi-instantaneously population inverted by 4d-shell ionization on the giant resonance followed by Auger decay. On the timescale of ∼10  ps to ∼100  ps (depending on parameters) a macroscopic polarization builds up in the medium, resulting in superfluorescent emission of several Xe lines in the forward direction. As the number of emitters in the system is increased by either raising the pressure or the pump-pulse energy, the emission yield grows exponentially over four orders of magnitude and reaches saturation. With increasing yield, we observe line broadening, a manifestation of superfluorescence in the spectral domain. Our novel theoretical approach, based on a full quantum treatment of the atomic system and the irradiated field, shows quantitative agreement with the experiment and supports our interpretation.

Time-resolved imaging of bound and dissociating nuclear wave packets in strong-field ionized iodomethane

We report the results of a time-resolved coincident ion momentum imaging experiment probing nuclear wave packet dynamics in the strong-field ionization and dissociation of iodomethane (CH₃I).

Beneficial effects on vision in patients undergoing retinal gene therapy for choroideremia

Retinal gene therapy is increasingly recognized as a novel molecular intervention that has huge potential in treating common causes of blindness, the majority of which have a genetic aetiology1-5. Choroideremia is a chronic X-linked retinal degeneration that was first described in 18726. It leads to progressive blindness due to deficiency of Rab-escort protein 1 (REP1). We designed an adeno-associated viral vector to express REP1 and assessed it in a gene therapy clinical trial by subretinal injection in 14 patients with choroideremia. The primary endpoint was vision change in treated eyes 2 years after surgery compared to unoperated fellow eyes. Despite complications in two patients, visual acuity improved in the 14 treated eyes over controls (median 4.5 letter gain, versus 1.5 letter loss, P = 0.04), with 6 treated eyes gaining more than one line of vision (>5 letters). The results suggest that retinal gene therapy can sustain and improve visual acuity in a cohort of predominantly late-stage choroideremia patients in whom rapid visual acuity loss would ordinarily be predicted.

Native Frames: Disentangling Sequential from Concerted Three-Body Fragmentation

A key question concerning the three-body fragmentation of polyatomic molecules is the distinction of sequential and concerted mechanisms, i.e., the stepwise or simultaneous cleavage of bonds. Using laser-driven fragmentation of OCS into O^{+}+C^{+}+S^{+} and employing coincidence momentum imaging, we demonstrate a novel method that enables the clear separation of sequential and concerted breakup. The separation is accomplished by analyzing the three-body fragmentation in the native frame associated with each step and taking advantage of the rotation of the intermediate molecular fragment, CO^{2+} or CS^{2+}, before its unimolecular dissociation. This native-frame method works for any projectile (electrons, ions, or photons), provides details on each step of the sequential breakup, and enables the retrieval of the relevant spectra for sequential and concerted breakup separately. Specifically, this allows the determination of the branching ratio of all these processes in OCS^{3+} breakup. Moreover, we find that the first step of sequential breakup is tightly aligned along the laser polarization and identify the likely electronic states of the intermediate dication that undergo unimolecular dissociation in the second step. Finally, the separated concerted breakup spectra show clearly that the central carbon atom is preferentially ejected perpendicular to the laser field.

Hetero-site-specific X-ray pump-probe spectroscopy for femtosecond intramolecular dynamics

New capabilities at X-ray free-electron laser facilities allow the generation of two-colour femtosecond X-ray pulses, opening the possibility of performing ultrafast studies of X-ray-induced phenomena. Particularly, the experimental realization of hetero-site-specific X-ray-pump/X-ray-probe spectroscopy is of special interest, in which an X-ray pump pulse is absorbed at one site within a molecule and an X-ray probe pulse follows the X-ray-induced dynamics at another site within the same molecule. Here we show experimental evidence of a hetero-site pump-probe signal. By using two-colour 10-fs X-ray pulses, we are able to observe the femtosecond time dependence for the formation of F ions during the fragmentation of XeF2 molecules following X-ray absorption at the Xe site.

Femtosecond charge and molecular dynamics of I-containing organic molecules induced by intense X-ray free-electron laser pulses

We studied the electronic and nuclear dynamics of I-containing organic molecules induced by intense hard X-ray pulses at the XFEL facility SACLA in Japan. The interaction with the intense XFEL pulse causes absorption of multiple X-ray photons by the iodine atom, which results in the creation of many electronic vacancies (positive charges) via the sequential electronic relaxation in the iodine, followed by intramolecular charge redistribution. In a previous study we investigated the subsequent fragmentation by Coulomb explosion of the simplest I-substituted hydrocarbon, iodomethane (CH₃I). We carried out three-dimensional momentum correlation measurements of the atomic ions created via Coulomb explosion of the molecule and found that a classical Coulomb explosion model including charge evolution (CCE-CE model), which accounts for the concerted dynamics of nuclear motion and charge creation/charge redistribution, reproduces well the observed momentum correlation maps of fragment ions emitted after XFEL irradiation. Then we extended the study to 5-iodouracil (C₄H₃IN₂O₂, 5-IU), which is a more complex molecule of biological relevance, and confirmed that, in both CH₃I and 5-IU, the charge build-up takes about 10 fs, while the charge is redistributed among atoms within only a few fs. We also adopted a self-consistent charge density-functional based tight-binding (SCC-DFTB) method to treat the fragmentations of highly charged 5-IU ions created by XFEL pulses. Our SCC-DFTB modeling reproduces well the experimental and CCE-CE results. We have also investigated the influence of the nuclear dynamics on the charge redistribution (charge transfer) using nonadiabatic quantum-mechanical molecular dynamics (NAQMD) simulation. The time scale of the charge transfer from the iodine atomic site to the uracil ring induced by nuclear motion turned out to be only ∼5 fs, indicating that, besides the molecular Auger decay in which molecular orbitals delocalized over the iodine site and the uracil ring are involved, the nuclear dynamics also play a role for ultrafast charge redistribution. The present study illustrates that the CCE-CE model as well as the SCC-DFTB method can be used for reconstructing the positions of atoms in motion, in combination with the momentum correlation measurement of the atomic ions created via XFEL-induced Coulomb explosion of molecules.

Intravitreal pegaptanib for the treatment of ischemic diabetic macular edema

Purpose

Pegaptanib has been shown to be effective in treating diabetic macular edema (DME). In the original Phase II/III trial, however, patients with macular ischemia were excluded. In this study, we treated patients with ischemic DME.

Methods

Macular ischemia was defined as a 30% increase in the area of the foveal avascular zone (FAZ) at 45 seconds on fundus fluorescein angiography. In addition, the participants had diffuse foveal-involving DME with a central subfield thickness (CST) of >300 μm on spectral-domain optical coherence tomography. Five intravitreal pegaptanib injections were given 6 weeks apart. The final study visit was 6 weeks after the fifth injection. The primary outcome was change in the size of FAZ. Secondary outcomes were change in best-corrected visual acuity (BCVA) and the change in CST.

Results

Thirty participants were enrolled. Three were unable to complete the full course of treatment. Their outcomes were carried forward for the first part of this analysis. There was no statistically significant change in the mean size of the FAZ from baseline to the final visit. Subclassifying participants as those with minimal/moderate ischemia (16 participants, FAZ area <1,000 pixels) and those with more severe ischemia (14 participants, FAZ area >1,000 pixels) also showed no statistically significant change in the mean area of the FAZ. On average, BCVA increased and CST decreased from baseline to the final visit, but these changes were not statistically significant. Using per protocol analysis on those participants who completed the full course of treatment, the mean BCVA increased from 49.2 to 53.9 letters (P=0.046).

Conclusion

In this study, intravitreal injection of pegaptanib did not significantly alter the size of the FAZ in participants with varying degrees of ischemic DME. There was, however, a significant improvement in mean BCVA in those who completed the treatment course.

Toward atomic resolution diffractive imaging of isolated molecules with X-ray free-electron lasers

We give a detailed account of the theoretical analysis and the experimental results of an X-ray-diffraction experiment on quantum-state selected and strongly laser-aligned gas-phase ensembles of the prototypical large asymmetric rotor molecule 2,5-diiodobenzonitrile, performed at the Linac Coherent Light Source [Phys. Rev. Lett.112, 083002 (2014)]. This experiment is the first step toward coherent diffractive imaging of structures and structural dynamics of isolated molecules at atomic resolution, i.e., picometers and femtoseconds, using X-ray free-electron lasers.

Multiple ionization and fragmentation dynamics of molecular iodine studied in IR-XUV pump-probe experiments

The ionization and fragmentation dynamics of iodine molecules (I(2)) are traced using very intense (∼10(14) W cm(-2)) ultra-short (∼60 fs) light pulses with 87 eV photons of the Free-electron LASer at Hamburg (FLASH) in combination with a synchronized femtosecond optical laser. Within a pump-probe scheme the IR pulse initiates a molecular fragmentation and then, after an adjustable time delay, the system is exposed to an intense FEL pulse. This way we follow the creation of highly-charged molecular fragments as a function of time, and probe the dynamics of multi-photon absorption during the transition from a molecule to individual atoms.

Electron rearrangement dynamics in dissociating I(2)^(n+) molecules accessed by extreme ultraviolet pump-probe experiments

The charge rearrangement in dissociating I_{2}^{n+} molecules is measured as a function of the internuclear distance R using extreme ultraviolet pulses delivered by the free-electron laser in Hamburg. Within an extreme ultraviolet pump-probe scheme, the first pulse initiates dissociation by multiply ionizing I_{2}, and the delayed probe pulse further ionizes one of the two fragments at a given time, thus triggering charge rearrangement at a well-defined R. The electron transfer between the fragments is monitored by analyzing the delay-dependent ion kinetic energies and charge states. The experimental results are in very good agreement with predictions of the classical over-the-barrier model demonstrating its validity in a thus far unexplored quasimolecular regime relevant for free-electron laser, plasma, and chemistry applications.

Epigenetic regulation in memory and cognitive disorders

While the importance of epigenetic mechanisms is well established for numerous aspects of cell differentiation and development, recent findings have shown epigenetic processes to be a critical regulatory component in postmitotic neurons. Particularly intriguing, and potentially significant, are data demonstrating epigenetic regulation of cognitive behaviors. Different aspects of learning and memory appear to be regulated at the level of epigenetic chromatin modifications. Furthermore, it is becoming clear that the dysfunction of epigenetic mechanisms can lead to various disorders accompanied by significant mental impairment. Here, we review the evidence for the epigenetic control of cognition and the role of epigenetic dysregulation in mental disorders. A better understanding of epigenetic mechanisms will increase our fundamental knowledge of cognition and also provide new and exciting avenues of treatment for various mental disorders.

Time-resolved measurement of interatomic coulombic decay in Ne2

The lifetime of interatomic Coulombic decay (ICD) [L. S. Cederbaum et al., Phys. Rev. Lett. 79, 4778 (1997)] in Ne2 is determined via an extreme ultraviolet pump-probe experiment at the Free-Electron Laser in Hamburg. The pump pulse creates a 2s inner-shell vacancy in one of the two Ne atoms, whereupon the ionized dimer undergoes ICD resulting in a repulsive Ne+(2p(-1))-Ne+(2p(-1)) state, which is probed with a second pulse, removing a further electron. The yield of coincident Ne+-Ne2+ pairs is recorded as a function of the pump-probe delay, allowing us to deduce the ICD lifetime of the Ne2(+)(2s(-1)) state to be (150±50)  fs, in agreement with quantum calculations.

Single-particle structure determination by correlations of snapshot X-ray diffraction patterns

Diffractive imaging with free-electron lasers allows structure determination from ensembles of weakly scattering identical nanoparticles. The ultra-short, ultra-bright X-ray pulses provide snapshots of the randomly oriented particles frozen in time, and terminate before the onset of structural damage. As signal strength diminishes for small particles, the synthesis of a three-dimensional diffraction volume requires simultaneous involvement of all data. Here we report the first application of a three-dimensional spatial frequency correlation analysis to carry out this synthesis from noisy single-particle femtosecond X-ray diffraction patterns of nearly identical samples in random and unknown orientations, collected at the Linac Coherent Light Source. Our demonstration uses unsupported test particles created via aerosol self-assembly, and composed of two polystyrene spheres of equal diameter. The correlation analysis avoids the need for orientation determination entirely. This method may be applied to the structural determination of biological macromolecules in solution.

Ultrafast charge rearrangement and nuclear dynamics upon inner-shell multiple ionization of small polyatomic molecules

Ionization and fragmentation of methylselenol (CH(3)SeH) molecules by intense (>10(17) W/cm(2)) 5 fs x-ray pulses (ħω=2 keV) are studied by coincident ion momentum spectroscopy. We contrast the measured charge state distribution with data on atomic Kr, determine kinetic energies of resulting ionic fragments, and compare them to the outcome of a Coulomb explosion model. We find signatures of ultrafast charge redistribution from the inner-shell ionized Se atom to its molecular partners, and observe significant displacement of the atomic constituents in the course of multiple ionization.

Ultrafast charge rearrangement and nuclear dynamics upon inner-shell multiple ionization of small polyatomic molecules

Ionization and fragmentation of methylselenol (CH(3)SeH) molecules by intense (>10(17) W/cm(2)) 5 fs x-ray pulses (ħω=2 keV) are studied by coincident ion momentum spectroscopy. We contrast the measured charge state distribution with data on atomic Kr, determine kinetic energies of resulting ionic fragments, and compare them to the outcome of a Coulomb explosion model. We find signatures of ultrafast charge redistribution from the inner-shell ionized Se atom to its molecular partners, and observe significant displacement of the atomic constituents in the course of multiple ionization.

Epigenetic regulation in memory and cognitive disorders

While the importance of epigenetic mechanisms is well established for numerous aspects of cell differentiation and development, recent findings have shown epigenetic processes to be a critical regulatory component in postmitotic neurons. Particularly intriguing, and potentially significant, are data demonstrating epigenetic regulation of cognitive behaviors. Different aspects of learning and memory appear to be regulated at the level of epigenetic chromatin modifications. Furthermore, it is becoming clear that the dysfunction of epigenetic mechanisms can lead to various disorders accompanied by significant mental impairment. Here, we review the evidence for the epigenetic control of cognition and the role of epigenetic dysregulation in mental disorders. A better understanding of epigenetic mechanisms will increase our fundamental knowledge of cognition and also provide new and exciting avenues of treatment for various mental disorders.

Fractal morphology, imaging and mass spectrometry of single aerosol particles in flight

The morphology of micrometre-size particulate matter is of critical importance in fields ranging from toxicology to climate science, yet these properties are surprisingly difficult to measure in the particles' native environment. Electron microscopy requires collection of particles on a substrate; visible light scattering provides insufficient resolution; and X-ray synchrotron studies have been limited to ensembles of particles. Here we demonstrate an in situ method for imaging individual sub-micrometre particles to nanometre resolution in their native environment, using intense, coherent X-ray pulses from the Linac Coherent Light Source free-electron laser. We introduced individual aerosol particles into the pulsed X-ray beam, which is sufficiently intense that diffraction from individual particles can be measured for morphological analysis. At the same time, ion fragments ejected from the beam were analysed using mass spectrometry, to determine the composition of single aerosol particles. Our results show the extent of internal dilation symmetry of individual soot particles subject to non-equilibrium aggregation, and the surprisingly large variability in their fractal dimensions. More broadly, our methods can be extended to resolve both static and dynamic morphology of general ensembles of disordered particles. Such general morphology has implications in topics such as solvent accessibilities in proteins, vibrational energy transfer by the hydrodynamic interaction of amino acids, and large-scale production of nanoscale structures by flame synthesis.

Nanoplasma dynamics of single large xenon clusters irradiated with superintense x-ray pulses from the linac coherent light source free-electron laser

The plasma dynamics of single mesoscopic Xe particles irradiated with intense femtosecond x-ray pulses exceeding 10(16)  W/cm2 from the Linac Coherent Light Source free-electron laser are investigated. Simultaneous recording of diffraction patterns and ion spectra allows eliminating the influence of the laser focal volume intensity and particle size distribution. The data show that for clusters illuminated with intense x-ray pulses, highly charged ionization fragments in a narrow distribution are created and that the nanoplasma recombination is efficiently suppressed.

Femtosecond dark-field imaging with an X-ray free electron laser

The emergence of femtosecond diffractive imaging with X-ray lasers has enabled pioneering structural studies of isolated particles, such as viruses, at nanometer length scales. However, the issue of missing low frequency data significantly limits the potential of X-ray lasers to reveal sub-nanometer details of micrometer-sized samples. We have developed a new technique of dark-field coherent diffractive imaging to simultaneously overcome the missing data issue and enable us to harness the unique contrast mechanisms available in dark-field microscopy. Images of airborne particulate matter (soot) up to two microns in length were obtained using single-shot diffraction patterns obtained at the Linac Coherent Light Source, four times the size of objects previously imaged in similar experiments. This technique opens the door to femtosecond diffractive imaging of a wide range of micrometer-sized materials that exhibit irreproducible complexity down to the nanoscale, including airborne particulate matter, small cells, bacteria and gold-labeled biological samples.

Ultrafast transitions from solid to liquid and plasma states of graphite induced by x-ray free-electron laser pulses

We used photon pulses from an x-ray free-electron laser to study ultrafast x-ray-induced transitions of graphite from solid to liquid and plasma states. This was accomplished by isochoric heating of graphite samples and simultaneous probing via Bragg and diffuse scattering at high time resolution. We observe that disintegration of the crystal lattice and ion heating of up to 5 eV occur within tens of femtoseconds. The threshold fluence for Bragg-peak degradation is smaller and the ion-heating rate is faster than current x-ray-matter interaction models predict.

Attosecond correlated dynamics of two electrons passing through a transition state

The strong-field induced decay of a doubly excited, transient Coulomb complex Ar**→Ar(2+)+2e(-) is explored by tracing correlated two-electron emission in nonsequential double ionization of Ar as a function of the carrier-envelope phase. Using <6 fs pulses, electron emission is essentially confined to one optical cycle. Classical model calculations support that the intermediate Coulomb complex has lost memory of its formation dynamics and allows for a consistent, though model-dependent definition of "emission time," empowering us to trace transition-state two-electron decay dynamics with sub-fs resolution. We find a most likely emission time difference of ∼200±100 as.

Second-order autocorrelation of XUV FEL pulses via time resolved two-photon single ionization of He

Second-order autocorrelation spectra of XUV free-electron laser pulses from the Spring-8 Compact SASE Source (SCSS) have been recorded by time and momentum resolved detection of two-photon single ionization of He at 20.45 eV using a split-mirror delay-stage in combination with high-resolution recoil-ion momentum spectroscopy (COLTRIMS). From the autocorrelation trace we extract a coherence time of 8 ± 2 fs and a mean pulse duration of 28 ± 5 fs, much shorter than estimations based on electron bunch-length measurements. Simulations within the partial coherence model [Opt. Lett. 35, 3441 (2010)] are in agreement with experiment if a pulse-front tilt across the FEL beam diameter is taken into account that leads to a temporal shift of about 6 fs between both pulse replicas.

Ultrafast extreme ultraviolet induced isomerization of acetylene cations

Ultrafast isomerization of acetylene cations ([HC=CH](+)) in the low-lying excited A(2)Σ(g)(+) state, populated by the absorption of extreme ultraviolet (XUV) photons (38 eV), has been observed at the Free Electron Laser in Hamburg, (FLASH). Recording coincident fragments C(+) + CH2(+) as a function of time between XUV-pump and -probe pulses, generated by a split-mirror device, we find an isomerization time of 52±15 fs in a kinetic energy release (KER) window of 5.8<KER<8 eV, providing clear evidence for the existence of a fast, nonradiative decay channel.

Multiphoton double ionization of Ar and Ne close to threshold

In kinematically complete studies we explore double ionization (DI) of Ne and Ar in the threshold regime (I>3x10{13} W/cm{2}) for 800 nm, 45 fs pulses. The basic differences are found in the two-electron momentum distributions-"correlation" (CO) for Ne and "anticorrelation" (ACO) for Ar-that can be partially explained theoretically within a 3D classical model including tunneling. Transverse electron momentum spectra provide insight into "Coulomb focusing" and point to correlated nonclassical dynamics. Finally, DI threshold intensities, CO as well as ACO regimes are predicted for both targets.

Diffraction properties of periodic lattices under free electron laser radiation

In this Letter, we report the pioneering use of free electron laser radiation for the investigation of periodic crystalline structures. The diffraction properties of silver behenate single nanocrystals (5.8 nm periodicity) with the dimensions of 20 nm x 20 nm x 20 microm and as powder with grain sizes smaller than 200 nm were investigated with 8 nm free electron laser radiation in single-shot modus with 30 fs long free electron laser pulses. This work emphasizes the possibility of using soft x-ray free electron laser radiation for these crystallographic studies on a nanometer scale.

Three-dimensional momentum imaging of electron wave packet interference in few-cycle laser pulses

Using a reaction microscope, three-dimensional (3D) electron (and ion) momentum (P) spectra have been recorded for carrier-envelope-phase (CEP) stabilized few-cycle ( approximately 5 fs), intense ( approximately 4 x 10(14) W/cm2) laser pulses (740 nm) impinging on He. Preferential emission of low-energy electrons (E(e)<15 eV) to either hemisphere is observed as a function of the CEP. Clear interference patterns emerge in P space at CEPs with maximum asymmetry, interpreted as attosecond interferences of rescattered and directly emitted electron wave packets by means of a simple model.

Cold-target recoil-ion momentum spectroscopy for diagnostics of high harmonics of the extreme-ultraviolet free-electron laser light source at SPring-8

We have developed a cold-target recoil-ion momentum spectroscopy apparatus dedicated to the experiments using the extreme-ultraviolet light pulses at the free-electron laser facility, SPring-8 Compact SASE Source test accelerator, in Japan and used it to measure spatial distributions of fundamental, second, and third harmonics at the end station.

Few-photon multiple ionization of N2 by extreme ultraviolet free-electron laser radiation

Few-photon multiple ionization of N2 was studied differentially in a reaction microscope using 44 eV, approximately 25 fs, intense ( approximately 10(13) W/cm(2)) photon pulses from FLASH. Sequential ionization is observed to dominate. For various intermediate charge states N(2)(n+0 we find a considerable excess of photons absorbed compared to the minimum number that would energetically be required. Photoionization of aligned N(2)(n+) ions, produced by photon absorption in sequential steps, is explored and few-photon absorption pathways are traced by inspecting kinetic energy releases and fragment-ion angular distributions.

Recoil-ion momentum distributions for two-photon double ionization of He and Ne by 44 eV free-electron laser radiation

Recoil-ion momentum distributions for two-photon double ionization of He and Ne (variant Planck's over omega=44 eV) have been recorded with a reaction microscope at FLASH (the free-electron laser at Hamburg) at an intensity of approximately 1 x 10(14) W/cm2 exploring the dynamics of the two fundamental two-photon-two-electron reaction pathways, namely, sequential and direct (or nonsequential) absorption of the photons. We find strong differences in the recoil-ion momentum patterns for the two mechanisms pointing to the significantly different two-electron emission dynamics and thus provide serious constraints for theoretical models.

Strong-field double ionization of Ar below the recollision threshold

Nonsequential double ionization of Ar by 45 fs laser pulses (800 nm) at (4-7)x10;{13} W/cm;{2} was explored in fully differential measurements. Well below the field-modified recollision threshold we enter the multiphoton regime. Strongly correlated back-to-back emission of the electrons along the polarization direction is observed to dominate in striking contrast to all previous data. No effect of Coulomb repulsion can be found, the predicted cutoff in the sum-energy spectra of two emitted electrons is confirmed, and the potential importance of multiple recollisions is discussed.

Correlated two-electron momentum spectra for strong-field nonsequential double ionization of He at 800 nm

We report on a kinematically complete experiment on nonsequential double ionization of He by 25 fs 800 nm laser pulses at 1.5 PW/cm;{2}. The suppression of the recollision-induced excitation at this high intensity allows us to address in a clean way direct (e,2e) ionization by the recolliding electron. In contrast with earlier experimental results, but in agreement with various theoretical predictions, the two-electron momentum distributions along the laser polarization axis exhibit a pronounced V-shaped structure, which can be explained by the role of Coulomb repulsion and typical (e,2e) kinematics.

Complete characterization of molecular dynamics in ultrashort laser fields

Reaction Microscope-based, complete, and time-resolved Coulomb explosion imaging of vibrating and dissociating D(2)(+) molecules with femtosecond time-resolution allowed us to perform an internuclear distance (R-)dependent Fourier analysis of the corresponding wave packets. Calculations demonstrate that the obtained two-dimensional R-dependent frequency spectra enable the complete characterization of the wave packet dynamics and directly visualize the field-modified molecular potential curves in intense, ultrashort laser pulses.

Few-photon multiple ionization of ne and ar by strong free-electron-laser pulses

Few-photon multiple ionization of Ne and Ar atoms by strong vacuum ultraviolet laser pulses from the free-electron laser at Hamburg was investigated differentially with the Heidelberg reaction microscope. The light-intensity dependence of Ne2+ production reveals the dominance of nonsequential two-photon double ionization at intensities of I<6x10(12) W/cm2 and significant contributions of three-photon ionization as I increases. Ne2+ recoil-ion-momentum distributions suggest that two electrons absorbing "instantaneously" two photons are ejected most likely into opposite hemispheres with similar energies.

Spatiotemporal imaging of ultrafast molecular motion: collapse and revival of the D+2 nuclear wave packet

We report on a real-time imaging of the ultrafast D(+)2 rovibrational nuclear wave-packet motion performed using a combination of a pump-probe setup with 7 fs laser pulses and a "reaction-microscope" spectrometer. We observe fast dephasing (collapse) of the vibrational wave packet and its subsequent revival and prove rotational excitation in ultrashort laser pulses. Channel-selective Fourier analysis of the wave packet's long-term (approximately 3000 fs) evolution allows us to resolve its individual constituents, revealing unique information on the mechanisms of strong-field ionization and dissociation.

Quantum-phase resolved mapping of ground-state vibrational D2 wave packets via selective depletion in intense laser pulses

Applying 7 fs pump-probe pulses (780 nm, 4 x 10(14) W/cm2) we observe electronic ground-state vibrational wave packets in neutral D2 with a period of T=11.101(70) fs by following the internuclear separation (R-)dependent ionization with a sensitivity of Delta<R><or=0.02 A. The absolute phase of the wave packet's motion provides evidence for R-dependent depletion of the ground state by nonlinear ionization, to be the dominant preparation mechanism. A phase shift of about pi found between pure ionization (D2+) and dissociation (D+ + D) channels opens a pathway of quantum control.

Time-resolved imaging and manipulation of H2 fragmentation in intense laser fields

We report on the experimental realization of time-resolved coincident Coulomb explosion imaging of H2 fragmentation in 10(14) W/cm(2) laser fields. Combining a high-resolution "reaction microscope" and a fs pump-probe setup, we map the motion of wave packets dissociating via one- or two-photon channels, respectively, and observe a new region of enhanced ionization. The long-term interferometric stability of our system allows us to extend pump-probe experiments into the region of overlapping pulses, which offers new possibilities for the manipulation of ultrafast molecular fragmentation dynamics.

Correlated multielectron dynamics in ultrafast laser pulse interactions with atoms

We present the results of the detailed experimental study of multiple ionization of Ne and Ar by 25 and 7 fs laser pulses. Whereas in multiple ionization of Ar different mechanisms, involving field ionization steps and recollision-induced excitations, play a role, for Ne only one channel, where the highly correlated instantaneous emission of up to four electrons is triggered by a recollisional electron impact, is found to be important. Using few-cycle pulses we are able to suppress those processes that occur on time scales longer than one laser cycle.

Production of interferons and change of the lymphocyte subpopulation phenotype in peripheral blood at cervical papillomavirus infection

IFN-gamma and IFN-alpha production in vitro by peripheral blood cells activated by phytohemagglutinin or the Newcastle disease virus was impaired in patients with a benign process, cervical intraepithelial neoplasm and cancer in situ associated with human papillomavirus infection. In case of IFN-gamma and IFN-alpha production impairment following cervical papillomavirus infection, the increased severity of disease was accompanied by remarkable IFN system suppression. The lower synthesis of both IFN correlated with changes of some lymphocyte-subpopulation phenotype in peripheral blood. Lower CD4+ and CD3+ DR+ T cell concentrations were observed in papillomavirus-infected patients with impaired IFN production; impaired IFN-gamma production was accompanied by lower CD4/CD8 index.