Search

Abstract The development of high intensity petawatt lasers has created new possibilities for ion acceleration and nuclear fusion using solid targets. In such laser-matter interaction, multiple ion species are accelerated with broad spectra up to hundreds of MeV. To measure ion yields and for species identification, CR-39 solid-state nuclear track detectors are frequently used. However, these detectors are limited in their applicability for multi-ion spectra differentiation as standard image recognition algorithms can lead to a misinterpretation of data, there is no unique relation between track diameter and particle energy, and there are overlapping pit diameter relationships for multiple particle species. In this report, we address these issues by first developing an algorithm to overcome user bias during image processing. Second, we use calibration of the detector response for protons, carbon and helium ions (alpha particles) from 0.1 to above 10 MeV and measurements of statistical energy loss fluctuations in a forward-fitting procedure utilizing multiple, differently filtered CR-39, altogether enabling high-sensitivity, multi-species particle spectroscopy. To validate this capability, we show that inferred CR-39 spectra match Thomson parabola ion spectrometer data from the same experiment. Filtered CR-39 spectrometers were used to detect, within a background of ~ 2 × 1011 sr−1 J−1 protons and carbons, (1.3 ± 0.7) × 108 sr−1 J−1 alpha particles from laser-driven proton-boron fusion reactions.

Abstract Amplification of attosecond pulses produced via high harmonic generation is a formidable problem since none of the amplifiers can support the corresponding PHz bandwidth. Producing the well defined polarization state common for a set of harmonics required for formation of the circularly/elliptically polarized attosecond pulses (which are on demand for dynamical imaging and coherent control of the spin flip processes) is another big challenge. In this work we show how both problems can be tackled simultaneously on the basis of the same platform, namely, the plasma-based X-ray amplifier whose resonant transition frequency is modulated by an infrared field.

Compact electron accelerators based on laser-plasma acceleration scheme may be useful for future light sources, radiation therapy etc. Here the authors demonstrate electron acceleration in laser plasma interaction via vacuum laser acceleration and relativistic transparency injection.

We present the first demonstration of multi-GeV laser wakefield acceleration in a fully optically formed plasma waveguide, with an acceleration gradient as high as 25 GeV/m. The guide was formed via self-waveguiding of

Laser irradiation of deuterated polyethylene nanowire arrays at intensities of 5×10^{19}Wcm^{–2} was recently reported to accelerate deuterons to multi-MeV energies, resulting in microscale fusion. Here we show that irradiation of deuterated nanowire targets at intensities of ∼3×10^{21}Wcm^{–2} with high contrast λ=400nm laser pulses of 45 fs duration leads to different plasma dynamics in which the tip of the nanowires rapidly explodes to form an overdense plasma, but the onset of relativistic transparency allows the ultrashort laser pulse to penetrate deep into the nanowire array, enhancing particle acceleration. Experiments and particle-in-cell simulations show that ions are accelerated in the laser beam backward direction to energies up to 13 MeV by a target normal sheath acceleration (TNSA) field that develops in the front of the target, forming collimated beams characterized by full wave at half maximum divergence as low as 7.5°. The simulations also show that deeper within the nanowire array ions are accelerated radially to MeV energies by an internal TNSA field normal to the nanowire surfaces. These radially accelerated deuterons collide with other D atoms, as do those directed toward the CD_{2} substrate, leading to D-D fusion reactions. Irradiation with 8 J laser pulses is measured to generate up to 1.2×10^{7} D-D fusion neutrons per shot. The simulations suggest the use of a thinner substrate would also accelerate ions originating from a small area in the back of the target in the laser forward direction.

We demonstrate image plane holographic microscopy in the soft X-ray (SXR) spectral region, combining the coherent output from a 46.9-nm wavelength table-top SXR laser and two Fresnel zone plates. Phase and amplitude maps of the object are simultaneously obtained from holograms created at the image plane by the superposition of a reference and object beam originating from the zero and first diffraction order of the zone plates. We have used the microscope to record holograms of nanometer-scale periodic Si elbow patterns with 30% absorption contrast at the laser wavelength. The measured phase shift of 2.3 rad accurately predicts the Si dense line step height of 100 nm. The scheme is scalable to shorter wavelengths and allows for simultaneous high spatial and temporal resolution.

The interaction of an extreme ultraviolet (EUV) laser beam with a parylene foil was studied by experiments and simulation. A single EUV laser pulse of nanosecond duration focused to an intensity of 3 × 1010 W cm−2 perforated micrometer thick targets. The same laser pulse was simultaneously used to diagnose the interaction by a transmission measurement. A combination of 2-dimensional radiation-hydrodynamic and diffraction calculations was used to model the ablation, leading to good agreement with experiment. This theoretical approach allows predictive modelling of the interaction with matter of intense EUV beams over a broad range of parameters.

We have demonstrated the efficient generation of sub-9-nm-wavelength picosecond laser pulses of microjoule energy at 1-Hz repetition rate with a tabletop laser. Gain-saturated lasing was obtained at λ=8.85 nm in nickel-like lanthanum ions excited by collisional electron-impact excitation in a precreated plasma column heated by a picosecond optical laser pulse of 4-J energy. Furthermore, isoelectronic scaling along the lanthanide series resulted in lasing at wavelengths as short as λ=7.36 nm. Simulations show that the collisionally broadened atomic transitions in these dense plasmas can support the amplification of subpicosecond soft-x-ray laser pulses.

We report a significant enhancement in both the energy and the flux of relativistic electrons accelerated by ultra-intense laser pulse irradiation (>1 × 10 21 W cm−2) of near solid density aligned CD2 nanowire arrays in comparison to those from solid CD2 foils irradiated with the same laser pulses. Ultrahigh contrast femtosecond laser pulses penetrate deep into the nanowire array creating a large interaction volume. Detailed three dimensional relativistic particle-in-cell simulations show that electrons originating anywhere along the nanowire length are first driven towards the laser to reach a lower density plasma region near the tip of the nanowires, where they are accelerated to the highest energies. Electrons that reach the lower density plasma experience direct laser acceleration up to the dephasing length, where they outrun the laser pulse. This yields an electron beam characterized by a 3× higher electron temperature and an integrated flux 22.4× larger respect to foil targets. Additionally, the generation of >1 MeV photons were observed to increase up to 4.5×. [ABSTRACT FROM AUTHOR]

We report on improved proton acceleration from the interaction of a short pulse high intensity laser (>1020 Wcm−2) with nano-engineered targets. Planar targets (from 7 to 20 μm) with protruding gold nanowires having different total areal densities, lengths, and diameters, ranging from 3% to 60% of the size of the laser focal spot were used during an experimental campaign at the 3 J, 30 fs HERCULES laser facility. The results show the importance of the average number of nanowires per focal spot, N, on laser energy absorption. We show that the proton acceleration is significantly improved by using 1 nanowires per focal spot. Detailed analysis indicates that 1 nanowire per focal spot optimizes the interaction between laser pulse and nanowires, in which the wings of the pulse pull out electrons from the wires forming a plasma with density that allows for deep penetration of the laser pulse into the array. When moving away from this optimum in both directions, N ≪ 1 and N ≫ 1, the laser pulse-nanowire coupling is either too weak or unfavorable for obtaining maximum proton energy. Proton spectra are compared to simulations using 2D-3V particle-in-cell code which reproduces the experimental data with good agreement. [ABSTRACT FROM AUTHOR]

Depression is the only silent cause that mainly affects the adult population and manifests itself in this case in 4% of the world population. However, more than three quarters of those affected belong to land in urbanization without receiving any type of treatment; a situation that represents a gap in access to mental health services. Now, the hallucinatory relationships mean that this condition has a high level of competition with chronic diseases such as HIV, diabetes, lung disease, asthma, arthritis, angina pectoris and cerebral palsy; Assimilation, it has been detected that patient with affective disorders such as coronary syndrome, inflammation, malnutrition, pain, stress and even critical stages of COVID-19 infection act as risk factors for the development of the disease. In this context, as a result of concern for public health, particularly in countries following the crisis, this study presents a proposal to carry out a review regarding the prevalence of depression in the presence of aggravated cases and crises. Strategies are implemented to address this situation. For this, a systematic review of the literature was carried out, complemented with bibliometric data on scientific contributions, with a period of 10 years (2011-2021) registered in the databases: Web of Science, Scopus and PubMed. In this way, the results allowed us to identify that, in recent years, in the fight to combat this problem, various remedies were used for its treatment and prevention; in which the focus is on the modification of health behaviors and collaborative care, which seeks quality of life in cases of patients with chronic diseases. On the other hand, the bibliometric information allows us to determine that the United States, Australia and Canada are the countries with the greatest scientific production on the subject. It is concluded that, although health services have demonstrated and improved their strategies in recent years, and that part of them have been supported by technological innovation, there are bridging markets at the cultural and socioeconomic level that the treatment and primary care of these patients.

Background: Blood pressure derangements are common in orthotopic liver transplantation (OLT), and are potentially associated with adverse outcomes if they are sustained. While this concept is often believed to be true, few have rigorously demonstrated the validity of this claim, especially in likely vulnerable OLT patients., Methods: We retrospectively investigated 827 patients who underwent OLT to determine the magnitude of these hemodynamic associations with adverse outcomes. The median value of the mean arterial pressure (MAP) and the fractional change in the median MAP between subsequent epochs (FCM) were calculated for every 5-minute epoch intraoperatively. Epochs were classified according to prespecified ranges of MAP and fractional changes in MAP (lability) between epochs. Multivariate stepwise logistic regression was used to model associations of risk factors and epochs of intraoperative blood pressure (BP) instability with primary (30-day mortality and/or graft failure) and secondary adverse outcomes., Results: Primary adverse outcomes occurred in 10.9% and 12.2% of patients for 30-day mortality and 30-day graft failure, respectively. Independent hemodynamic predictors for 30-day mortality and graft failure included sustained periods of MAP <50 mmHg and BP lability where the MAP changed >25%. All of these values were statistically significant., Conclusion: Although severe intraoperative hypotension and BP lability during OLT are often observed in current practice as consequences of major surgical manipulations and patient vulnerability, these are likely not benign conditions based on this retrospective analysis. Prospective trials are warranted to investigate the possibility that interventions tailored to avoidance of hypotension and BP lability may improve outcomes.

Although Mycoplasma pneumonia infection is relatively common among school-aged children, it rarely leads to SJS. Herein, we report a seven-yr-old girl who presented with a Mycoplasma pneumonia infection that progressed to SJS five months after liver transplant. We suggest that children presenting with symptoms of Mycoplasma pneumonia infection in the immunosuppressed post-liver transplant setting be properly diagnosed and treated rapidly, as well as observed for symptoms of SJS and potentially serious extrapulmonary complications., (© 2010 John Wiley & Sons A/S.)

We report the demonstration of reflection mode imaging of 100 nm-scale features using 46.9 nm light from a compact capillary-discharge laser. Our imaging system employs a Sc/Si multilayer coated Schwarzschild condenser and a freestanding zone plate objective. The reported results advance the development of practical and readily available surface and nanostructure imaging tools based on the use of compact sources of extreme ultraviolet light.

We report average powers exceeding 1 microwatt in laser transitions of Ne-like ions at wavelengths near 30 nm. Gain-saturated operation was obtained at a repetition rate of 5 Hz exciting solid targets with pump pulses of ~1 J energy and 8 ps duration impinging at grazing incidence of 20 degrees. Gain-length products of about 20 were obtained in the 30.4 nm and 32.6 nm transitions of Ne-like V and Ne-like Ti respectively. Strong lasing was also observed in Ne-like Cr at 28.6 nm and in the 30.1 nm line of Ne-like Ti.

We investigated concerted evolution of rRNA genes in multiple populations of Tragopogon mirus and T. miscellus, two allotetraploids that formed recurrently within the last 80 years following the introduction of three diploids (T. dubius, T. pratensis, and T. porrifolius) from Europe to North America. Using the earliest herbarium specimens of the allotetraploids (1949 and 1953) to represent the genomic condition near the time of polyploidization, we found that the parental rDNA repeats were inherited in roughly equal numbers. In contrast, in most present-day populations of both tetraploids, the rDNA of T. dubius origin is reduced and may occupy as little as 5% of total rDNA in some individuals. However, in two populations of T. mirus the repeats of T. dubius origin outnumber the repeats of the second diploid parent (T. porrifolius), indicating bidirectional concerted evolution within a single species. In plants of T. miscellus having a low rDNA contribution from T. dubius, the rDNA of T. dubius was nonetheless expressed. We have apparently caught homogenization of rDNA repeats (concerted evolution) in the act, although it has not proceeded to completion in any allopolyploid population yet examined.

The primary structure of the Streptococcus mutans lantibiotic mutacin 1140 was elucidated by NMR spectroscopy, mass spectrometry, and chemical sequencing. The structure is in agreement with other closely related lantibiotics, such as epidermin. A novel method was developed in which mutacin 1140 was chemically modified with sodium borohydride followed by ethanethiol, allowing the differentiation of the thioether-containing residues from the dehydrated residues. This double-labeling strategy provides a simple method to reliably identify all modified lantibiotic residues with a minimal amount of material. While NMR spectroscopy is still required to obtain thioether bridging patterns and thus the complete covalent structure, the double-labeling technique, along with mass spectrometry, provides most of the information in a fraction of the time required for a complete NMR analysis. Thus, with these new techniques lantibiotics can be rapidly characterized.

This paper examines the anatomy and physiology, together with the pathophysiology, of the ventricular system of the brain, as it was understood by arguably its greatest exponent in Western Antiquity, Galen. According to him, the purpose of the ventricles was to elaborate, store and distribute psychic pneuma, the motive force of Galenic neurology, throughout the nervous system. However, impressive as the delineation of the ventricular system is, the details of this distribution are not forthcoming from Galen. Finally, I discuss the ventricles as the site of intellect, a notion only tentatively advanced by Galen, but cast into dogma by his successors. For all the mistakes Galen made in anatomy and physiology, the study of the ventricular system reveals a mind not dissimilar to our own.

Background: Information regarding the self-association of small peptide motifs can be used in the design of peptide microstructures. Previous work in our laboratories illustrated the self-association of certain diamide diacids into microcapsules. In this report a series of cyclohexane diamide diacids are investigated. The cyclohexylene (R-C6H10-R) system (with its axial and equatorial requirements) provided an opportunity to study the influence of molecular conformation upon the self-aggregation process., Results: Condensation of the respective cis- and trans-1,2-, 1,3-, and 1,4- cyclohexane dicarboxylic acid platforms with two equivalents of a L-Phe ester followed by deprotection gave the desired diamide diacids. Basic solutions of cis-1,2-, trans-1,3-, and cis-1,4-diamide diacids generated solid microspheres when acidified to pH 2.4. Molecular modeling revealed that 1,3-diaxial interactions favor a helical turn within these diamides., Conclusions: Access to 'complementary' molecular geometries is needed to self-associate into microscopic architectures.

The atomic force microscope (AFM) and the transmission electron microscope (TEM) have been used to study the morphology of isolated mouse thymocyte microdomains and Thy-1 antigen distribution at the surface of these structures. AFM images were recorded in air in the contact mode on membrane vesicles deposited on previously heated tissue culture plastic sheets and indirectly immunolabeled for Thy-1 expression with colloidal gold-conjugated secondary antibodies. AFM images of untreated plastic plates showed a very characteristic network of streaks 20-200 nm wide. Heating the plastic removed the streaks and provided flat surfaces (r.m.s. 1 nm). This substrate allowed strong adsorption and homogeneous spreading of the vesicles and easy manipulations during immunolabeling experiments. Vesicles flattened on the substrate without losing their morphology. The 10-nm membrane-bound gold beads were reproducibly imaged without degradation by repeated tip scanning. The observed microdomains had a mean diameter of 184 +/- 76 nm, and 65% of them were specifically labeled. Images obtained with the TEM on the same vesicles, deposited on carbon-coated grids and negatively stained, confirmed the AFM observations. The size distribution of the microdomains was quite similar, but the number of beads per vesicle was significantly higher, and 76% of the vesicles were labeled. The difference may be explained 1) by removal of beads from the vesicles in the additional washing step with water, which was necessary for the AFM; 2) by tip-sample convolution; and 3) by statistical fluctuations.

The nucleotide sequence of four anti-(Glu60-Ala30-Tyr10)n (GAT) monoclonal gamma 1 heavy chain mRNAs was determined from codon 10 to 120. This sequence overlaps with the NH2-terminal amino acid sequence, allowing elucidation of the complete protein sequence encompassing regions VH, D and JH. These sequences, which are highly conserved, indicate that anti-GAT antibodies expressing the same public idiotypic specificities represent a paucigene system, which uses at least two D-J combinations leading to functionally similar hypervariable regions involved in the recognition of the dominant Glu-Tyr determinant. D regions are encoded by D genes which are closely related either to the D-SP2 or the D.FL16 germ line gene cores.