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Family caregivers contribute to the sustainability of healthcare systems. Stroke is a leading cause of adult disability and many people with stroke rely on caregiver support to return home and remain in the community. Research has demonstrated the importance of caregivers, but suggests that caregiving can have adverse consequences. Despite the body of qualitative stroke literature, there is little clarity about how to incorporate these findings into clinical practice. This review aimed to characterise stroke caregivers' experiences and the impact of these experiences on their health and well-being. We conducted a qualitative meta-synthesis. Four electronic databases were searched to identify original qualitative research examining stroke caregivers' experiences. In total, 4,481 citations were found, with 39 studies remaining after removing duplicates and applying inclusion and exclusions criteria. Articles were appraised for quality using the Critical Appraisal Skills Programme (CASP), coded using NVivo software, and analysed through thematic synthesis. One overarching theme, 'caregiving is a full-time job' was identified, encompassing four sub-themes: (a) restructured life, (b) altered relationships, (c) physical challenges, and (d) psychosocial challenges. Community and institution-based clinicians should be aware of the physical and psychosocial consequences of caregiving and provide appropriate supports, such as education and respite, to optimise caregiver health and well-being. Future research may build upon this study to identify caregivers in most need of support and the types of support needed across a broad range of health conditions.

Background Our aim in this study was to evaluate long-term efficiency of hepatic venous balloon angioplasty (BA) and stent placement (SP) for hepatic venous outflow obstruction (HVOO) in pediatric liver transplantation (LT). Methods From January 1999 to September 2016, 262 pediatric patients underwent LT at our hospital. Ten were diagnosed with HVOO, which included 8 living donor grafts and 2 split liver grafts. BA and SP were used in management of these 10 patients with HVOO. After intervention, Doppler ultrasound (DUS) was the major follow-up modality for comparing efficiency of BA and SP. Results The incidence of HVOO was 3.8% (10 of 262) in our pediatric LTs. Of the 10 HVOO cases, 5 had SP, 3 had BA once, 1 had BA twice, and 1 had BA twice along with SP. The patent hepatic vein was maintained after a mean follow-up of 7.4 (range, 0.04–17) years. Recurrent rate of HVOO after BA was 42%. Neither recurrent HVOO nor stent migration occurred after SP and throughout long-term follow-up. Conclusion Hepatic venous SP was found to be more effective and safe than BA for treatment of HVOO in pediatric LT for long-term follow-up.

Phasor measurement units (PMUs) provide great potential for monitoring an electrical grid by recording synchronized measurements across a wide area. However, with more and more PMUs being deployed, the traditional workflow of processing these data is facing a major challenge. In this chapter, we present our experience in analyzing and mining PMU data for event classification and anomaly detection. Experiments have been carried out using real PMU data that are collected from the Bonneville Power Administration’s power grid. Experimental results show that our methods are effective in identifying both anomalies and known events from a large amount of data. Particularly, our classification method can accurately detect an event from a PMU that is far from the location where the event occurs.

State-specific desorption for SiCl4 adsorbed on a Si(100) surface at approximately 90 K with variable coverage following the Cl 2p and Si 2p core-level excitations has been investigated using synchrotron radiation. The Cl+ yields show a significant enhancement following the Cl 2p-->8a*1 excitation. The Cl- yields are notably enhanced at the 8a*1 resonance at both Cl 2p and Si 2p edges. The enhancement of the Cl- yield occurs through the formation of highly excited states of the adsorbed molecules. These results provide some new dissociation processes from adsorbates on surfaces via core-level excitation.

Photon-stimulated ion desorption (PSID) from solid Si(CH3)2Cl2 following Cl 2p core-level excitation has been investigated along with the resonant photoemission spectra using synchrotron radiation. The Cl L23-edge total-electron yield spectrum of solid Si(CH3)2Cl2 mainly exhibits the Cl 2p→15a1*, Cl 2p→10b1* and shape resonance peaks. A significant dissimilarity between the Cl L23-edge total-electron yield spectrum and Cl+ PSID spectrum of solid Si(CH3)2Cl2 is observed. The desorption of atomic Cl+ ions is detected predominantly at the Cl 2p→15a1* excitation, while scarcely any Cl+ ions are observed following the Cl 2p→10b1* excitation and Cl 2p→shape resonance excitation. This indicates that the character of bound terminating orbital has a significant influence on the desorption processes. The enhanced Cl+ desorption yield at the Cl 2p→15a1* resonance is attributed to the the fast desorption process originating from the localization of the spectator electron in the strong antibonding orbital.

High-resolution Si L23-edge x-ray absorption near-edge structure (XANES) total electron yield (TEY) spectrum and photon stimulated ion desorption (PSID) spectra of condensed Si(CH3)2Cl2 have been measured in the energy range of 102–115 eV using synchrotron radiation. Excitation from Si 2p to a Si–C antibonding orbital enhances the CH3+ formation, while excitation to the Si–Cl antibonding orbital gives rise to a pronounced Cl+ production. This indicates that the character of the bound terminating orbital has a significant influence on the fragmentation processes. The selective enhancement of H+ yield at a peak of ∼106.0 eV is interpreted in terms of the excited electron in the bound orbital with strong C–H antibonding character. Applying resonant photoemission spectroscopy, the spectator Auger process was found to be the dominant decay channel for the resonantly excited Si(2p) core hole of condensed Si(CH3)2Cl2. The close resemblance of the TEY and PSID spectra of solid Si(CH3)2Cl2 was attributable to spec...

Using the high resolution vacuum ultraviolet (vuv) photon source provided by the monochromatized undulator synchrotron radiation of the Chemical Dynamics Beamline at the Advanced Light Source, we have measured the photoionization efficiency (PIE) spectrum for Ne in the energy range of 21.56–21.67 eV at a wavelength resolution of 0.3 meV [full width at half‐maximum (FWHM)]. The PIE spectra for Ne obtained using 0.76 and 2.4 V/cm electric fields reveal autoionizing features attributable to the Rydberg states Ne[2p5ns′(1/2)1; n=14–29] and Ne[2p5nd′(3/2)1; n=12–35] converging to the spin–orbit excited Ne+(2P1/2) state. The positions of these Rydberg states are compared to previous experimental results and those calculated using the quantum defects and IE for Ne+(2P1/2) given in Moore [Natl. Stand Ref. Data Ser. Natl. Bur. Stand. 35 (1971)]. We have also observed mass analyzed threshold ions (MATI) for Ne formed in the Ne+(2P3/2,1/2) states. For Ar, only the MATI peak for Ar+(2P3/2) is observed. The failure to...

We investigated the dissociation dynamics of positive-ion and negative-ion fragments of gaseous and condensed HCCl(3) following photoexcitation of Cl 2p electrons to various resonances. Based on ab initio calculations at levels HF/cc-pVTZ and QCISD/6-311G∗, the first doublet structures in Cl L-edge x-ray absorption spectrum of HCCl(3) are assigned to transitions from the Cl (2P(3/2),(1/2)) initial states to the 10a(1)(∗) orbitals. The Cl 2p → 10a(1)(∗) excitation of HCCl(3) induces a significant enhancement of the Cl(+) desorption yield in the condensed phase and a small increase in the HCCl(+) yield in the gaseous phase. Based on the resonant photoemission of condensed HCCl(3), excitations of Cl 2p electrons to valence orbitals decay predominantly via spectator Auger transitions. The kinetic energy distributions of Cl(+) ion via the Cl 2p → 10a(1)(∗) excitation are shifted to higher energy ∼0.2 eV and ∼0.1 eV relative to those via the Cl 2p → 10e(∗) excitation and Cl 2p → shape resonance excitation, respectively. The enhancement of the yields of ionic fragments at specific core-excited resonance states is assisted by a strongly repulsive surface that is directly related to the spectator electrons localized in the antibonding orbitals. The Cl(-) anion is significantly reinforced in the vicinity of Cl 2p ionization threshold of gaseous HCCl(3), mediated by photoelectron recapture through post-collision interaction.

Following photoexcitation of Cl 2p electrons to various resonances, the dissociation dynamics of ionic and excited neutral fragments of gaseous CH{sub 2}Cl{sub 2} was investigated by combined measurements of photon-induced ionic dissociation, x-ray absorption, and uv-visible dispersed fluorescence. The Cl 2p core-to-Rydberg excitations near the ionization threshold produce a notable enhancement of excited neutral fragments (C* and CH*), which is attributed to the contribution from a shake-modified resonant Auger decay and postcollision interaction. The excitation Cl 2p {yields}10 a{sub 1}* induces an enhanced yield of CH{sub 2}{sup +}, possibly originating from fast dissociation via a strongly repulsive surface. The experimental results provide insight into the dissociation dynamics of ionic and excited neutral fragment production following core-level excitation.

We present a combined experimental and theoretical study on the $\text{Mn}\text{ }3d$ orbital occupation in orthorhombic ${\text{DyMnO}}_{3}$ single crystals. We have observed a very strong polarization dependence in the $\text{Mn}\text{ }{L}_{2,3}$ x-ray absorption spectra, indicative for a distinct anisotropic orbital occupation. Ab initio electronic-structure calculations clearly infer the existence of a strong orbital polarization in the ${e}_{g}$ band with a staggered ${d}_{3{x}^{2}\ensuremath{-}{r}^{2}}/{d}_{3{y}^{2}\ensuremath{-}{r}^{2}}$-type ordering pattern in the $ab$ plane. This finding is in excellent agreement with a quantitative analyis of the spectra using the atomic multiplet cluster approach.

The dissociation dynamics of anionic and excited neutral fragments of gaseous ${\text{CCl}}_{4}$ and ${\text{CCl}}_{4}$ adsorbed on Si(100) $\ensuremath{\sim}90\text{ }\text{K}$ following $\text{Cl}\text{ }2p$ core-level excitations were investigated on combining measurements of photon-induced anionic dissociation, x-ray absorption, and uv-visible dispersed fluorescence. The transitions of core electrons to high Rydberg states or doubly excited states near $\text{Cl}\text{ }2p$ ionization thresholds of gaseous ${\text{CCl}}_{4}$ remarkably enhance the production of excited neutral fragments (${\text{C}}^{\ensuremath{\ast}}$ and ${\text{CCl}}^{\ensuremath{\ast}}$); this enhancement is attributed to the contribution from the shake-modified resonant Auger decay and/or postcollision interaction (PCI). The ${\text{Cl}}^{\ensuremath{-}}$ anion is significantly reinforced in the vicinity of the $\text{Cl}\text{ }2{p}_{1/2,3/2}$ ionization threshold of gaseous ${\text{CCl}}_{4}$, originating from PCI-mediated photoelectron recapture. The $\text{Cl}\text{ }2p\ensuremath{\rightarrow}7{a}_{1}^{\ensuremath{\ast}}$ excitation for ${\text{CCl}}_{4}/\text{Si}(100)$ at $\ensuremath{\sim}90\text{ }\text{K}$ enhances the ${\text{Cl}}^{\ensuremath{-}}$ desorption yield at a submonolayer level. This resonant enhancement of ${\text{Cl}}^{\ensuremath{-}}$ yield at the $7{a}_{1}^{\ensuremath{\ast}}$ resonance in the $\text{Cl}\text{ }2p$ edge at a submonolayer level occurs through the formation of high-lying molecular-ion states of ${\text{CCl}}_{4}$ adsorbed on a Si surface.

By using two-photon resonant ionisation and a thermionic diode detector, the collision-induced two-photon forbidden 6s2 1S-6snp 1P transitions (n>29) have been observed at P(Ba) approximately 0.13 Torr and P(Ar) approximately 15 Torr. The forbidden transitions are attributed to the dimer excimer Ba2 processes. The minimum quantum number, n approximately 28 is calculated by using the l-mixing model and perturbation theory, which is in good agreement with the authors' observation.

State-specific dissociation dynamics for excited fragments of gaseous SiCl{sub 4} following Cl 2p and Si 2p core-level excitations were characterized by the dispersed UV/optical fluorescence spectroscopy. The core-to-Rydberg excitations at both Si 2p and Cl 2p edges lead to a noteworthy production of excited atomic fragments, neutral and ionic (Si{sup *},Si{sup +*}). In particular, the excited neutral atomic fragments Si{sup *} are significantly reinforced. The core-to-valence excitation at the Si 2p edge generates an enhancement of excited molecular-ion SiCl{sub 4}{sup +}. The experimental results provide deeper insight into the dissociation dynamics for excited neutral fragments of molecules via core-level excitation.

DNA tests in normal subjects and patients with ataxia and Parkinson's disease (PD) were carried out to assess the frequency of spinocerebellar ataxia (SCA) and to document the distribution of SCA mutations underlying ethnic Chinese in Taiwan. MJD/SCA3 (46%) was the most common autosomal dominant SCA in the Taiwanese cohort, followed by SCA6 (18%) and SCA1 (3%). No expansions of SCA types 2, 10, 12, or dentatorubropallidoluysian atrophy (DRPLA) were detected. The clinical phenotypes of these affected SCA patients were very heterogeneous. All of them showed clinical symptoms of cerebellar ataxia, with or without other associated features. The frequencies of large normal alleles are closely associated with the prevalence of SCA1, SCA2, MJD/SCA3, SCA6, and DRPLA among Taiwanese, Japanese, and Caucasians. Interestingly, abnormal expansions of SCA8 and SCA17 genes were detected in patients with PD. The clinical presentation for these patients is typical of idiopathic PD with the following characteristics: late onset of disease, resting tremor in the limbs, rigidity, bradykinesia, and a good response to levodopa. This study appears to be the first report describing the PD phenotype in association with an expanded allele in the TATA-binding protein gene and suggests that SCA8 may also be a cause of typical PD.

State-selective fragmentation dynamics for excited fragments and ionic fragments of gaseous and condensed Si(CH3)2Cl2 following Cl 2p and Si 2p core-level excitations have been characterized. The Cl 2p--15a1* excitation of Si(CH3)2Cl2 induces significant enhancement of the Cl+ desorption yield in the condensed phase and the Si(CH3)+2 and SiCH+3 yields in the gaseous phase. The core-to-Rydberg excitations at both Si 2p and Cl 2p edges lead to enhanced production of the excited fragments. These complementary results provide deeper insight into the origin of state-selective fragmentation of molecules via core-level excitation.

The use of 3-dimensional computed tomography (CT) imaging has been applied to the craniofacial region as well as to many other parts of the human body. Quantitative measurements have frequently been performed on the 3-dimensional images. However, critical validation of the measurement has been insufficient in the literature. This study was designed to evaluate the errors of the 3-dimensional measurements.Four phantom objects, a cube, a sphere, a cylinder, and a life-size adult skull model, were scanned using standard CT acquisition protocol. The data were transferred, reformatted, and displayed on an IBM-compatible personal computer running AnalyzePC 2.5 software. Linear, area, and volume measurements were obtained using one of the two methods. The first was physical measurement of the phantom objects using a caliper for linear measurement and mathematical calculations for area and volume measurements. The second was done by computer measurement on 3-dimensional images using the AnalyzePC 2.5 program. Each measurement was performed twice. The differences were compared between the repeated measurements and between the two methods.The images were displayed according to standard 3-dimensional CT protocol. The differences between the measurements were insignificant and ranged from 0.00 to 2.57%.This study validated the accuracy of the quantitative measurements on 3-dimensional CT images.

State-specific desorption for SiCl4 adsorbed on a Si(100) surface at approximately 90 K with variable coverage following the Cl 2p and Si 2p core-level excitations has been investigated using synchrotron radiation. The Cl+ yields show a significant enhancement following the Cl 2p--8a*1 excitation. The Cl- yields are notably enhanced at the 8a*1 resonance at both Cl 2p and Si 2p edges. The enhancement of the Cl- yield occurs through the formation of highly excited states of the adsorbed molecules. These results provide some new dissociation processes from adsorbates on surfaces via core-level excitation.

Caffeine which is present in soft drinks has been shown to increase alertness and allays drowsiness and fatigue. The aim of this study is to investigate whether caffeine could produce a long-term effect on the synaptic transmission using extracellular recording technique in the hippocampal slices. Bath application of caffeine (100 microM) reversibly increased the slope of field excitatory postsynaptic potential (fEPSP). Forskolin (25 microM) by its own did not affect the fEPSP significantly. However, in the presence of caffeine, forskolin induced a long-term potentiation (LTP) of fEPSP. Enprofylline which has been shown to exhibit some actions like caffeine but with a low adenosine antagonistic potency did not affect the normal synaptic transmission or the effect of forskolin at a lower concentration (10 microM). However, when the concentrations were increased to 20 and 50 microM, enprofylline significantly enhanced the fEPSP slope and promoted forskolin-induced LTP. The parallel increase of fEPSP and promotion of LTP observed with enprofylline suggests that adenosine A1 antagonism is the primary mechanism behind caffeine's effect. This hypothesis was further strengthened by the finding that promotion of forskolin-induced LTP was mimicked by the non-xanthine adenosine antagonist 9-chloro-2-(furyl)[1,2,4]triazolo [1,5-c]quinazolin-5-amine (CGS 15943). The promotion of forskolin-induced LTP provides a cellular basis behind caffeine's increase in capacity for sustained intellectual performance.

The bacterium Serratia marcescens shows population surface migration (swarming) phenomenum on an LB swarming plate, and differentiated cells can be observed at the swarming front. How the cell population differentiates during swarming on the agar surface is not known, neither is it clear whether cells with differentiated characteristics can be observed in broth culture. To monitor the population cell differentiation in a highly sensitive way without cell destruction, experiments were designed using bacterial luciferase genes luxAB as the reporter genes to allow direct monitoring of the differentiating cells through bioluminescence. An isogenic S. marcescens strain was constructed with luxAB under the control of the promoter of flagellin gene hag (phag::luxAB). Patterns of cell differentiation were monitored either by direct X-ray film exposure and/or by Autolumat luminometer detection. Results show that population cell differentiation on the agar surface occurs first in a temporal and then spatial way during colonial growth. It was also found that cells harvested from both the spreading agar plate and broth culture showed differentiation patterns similar to those from swarming cells, suggesting that the agar surface culture may not be essential for the formation of differentiated cells.

The reactions of Na2 with O2 were studied in a crossed-beam experiment at collision energies (Ec) of 8 and 23 kcal/mol. The formation of NaO2 + Na was observed at both collision energies, with the angular distributions of NaO2 in the center of mass coordinates peaking strongly forward with respect to the direction of the O2 beam, suggesting that the reaction is completed in a time scale that is shorter than one rotational period of the molecular system. From the velocity distribution of the products, we found that the newly formed NaO2 molecules are internally excited, with less than 20% of the available energy appearing in the translational motion of the separating products. These results indicate a “spectator stripping” mechanism, with the O2 stripping one Na off the Na2 molecule. At Ec = 23 kcal/mol, the cross section for this reaction channel, σNaO2, is estimated to be 0.8 A2. Another reaction channel which produces NaO + NaO was seen at Ec = 23 kcal/mol. The angular distribution for NaO is broad and forward-backward symmetric in the center-of-mass frame. A substantial fraction of the available energy is released into the relative motion of the products. This reaction is likely to proceed on an excited potential energy surface since a charge transfer to the excited O2 − orbitals seems necessary for breaking the O-O bond. The measurement yields a bond energy of 60 kcal/mol for the Na-O molecule, and a total cross section for this reaction channel at Ec = 23 kcal/mol, σNaO = 2 A2.

The reactions of Na{sub 2} with O{sub 2} were studied in a crossed-beam experiment at collision energies (E{sub c}) of 8 and 23 kcal/mol. The formation of NaO{sub 2} + Na was observed at both collision energies, with the angular distributions of NaO{sub 2} in the center of mass coordinates peaking strongly forward with respect to the direction of the O{sub 2} beam, suggesting that the reaction is completed in a time scale that is shorter than one rotational period of the molecular system. From the velocity distribution of the products, the authors found that the newly formed NaO{sub 2} molecules are internally excited, with less than 20% of the available energy appearing in the translational motion of the separating products. These results indicate a ``spectator stripping`` mechanism for the reaction, with the O{sub 2} stripping one Na off the Na{sub 2} molecules. At E{sub c} = 23 kcal/mol the cross section for this reaction channel is estimated to be 0.8 {angstrom}{sup 2}. Another reaction channel which produces NaO + NaO was seen at E{sub c} = 23 kcal/mol. The angular distribution for NaO is broad and forward-backward symmetric in the center of mass frame. A substantial fraction of the available energy is released into the relative motion of the products. This reaction is likely to proceed on an excited potential energy surface since a charge transfer to the excited O{sub 2}{sup {minus}} orbitals seems necessary for breaking the O-O bond. The measurement yields a bond energy of 60 kcal/mol for the Na-O molecule, and a total cross section of 2 {angstrom}{sup 2} for this reaction channel at E{sub c} = 23 kcal/mol.

We have earlier demonstrated that 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP) produces a direct toxicity on DA neurons in the substantia nigra (SN) and norepinephrine (NE) neurons in the locus coeruleus (LC) other than in the terminals. These results suggest that DA neurons in the SN and NE neurons in the LC are possibly able to uptake MPP+ through the DA and NE uptake systems, respectively, presumably via DA and NE dendrites. The present study examined this hypothesis. Adult male BALB/c mice were used. In the first part, animals received various combinations of nomifensine (NOM, a specific DA uptake blocker) and MPTP treatment. NOM was infused to the SN or striatum at 1.5 μg and 3.0 μg per day for a total of seven days. The infusion volume was 0.25 and 0.5 μl, respectively. MPTP was given systemically (IP) at 30 mg/kg per day for a total of seven days. On each day, NOM was given 30 min prior to MPTP injection. In the second part, animals received the same combinations of desimipramine (DMI, a specific NE uptake blocker) and MPTP treatments. DMI was infused to the LC and hippocampus at 1.25 μg and 2.5 μg per day 30 min before MPTP injection for a total of 7 days. The volumes of infusion were 0.25 μl in the LC and 0.5 μl in the hippocampus. Animals were subject to locomotor activity test 7 days after the last MPTP, MPP+ (saline) injections. They were then sacrificed and brain tissues of the striatum and hippocampus were subject to DA and NE analyses with HPLC fluorescence detection. Results indicated that MPTP consistently and markedly decreased DA level in the striatum and NE level in the hippocampus. It also impaired locomotor activity and produced long-lasting tremor in mice. NOM pretreatment in the striatum completely prevented MPTP’s toxicity, while NOM pretreatment in the SN only partially, but significantly, prevented MPTP’s toxicity on both DA and motor activity.

With x-ray spectroscopy and first-principles calculations, we expose the electronic structure, near the Fermi level, of Co-doped PbPdO2 composed of O 2p-Pd 4d hybridized states with an additional contribution of a spin-polarized Co 3d state at either a greater or smaller energy. The spin-polarized Co 3d states interacting with O 2p-Pd 4d hybridized states cause spin splitting at the band edge. Fascinating physical properties such as high-temperature ferromagnetism thus arise in Co-doped PbPdO2. Results will help in the design of materials with desired electronic structures and the control of spin polarization with chemical doping.

We present experimental evidence of the gapless band structure of PbPdO2 by combined x-ray photoemission and x-ray absorption spectra complemented with first principles band structure calculations. The electronic structure near the Fermi level of PbPdO2 is mainly composed of O 2p and Pd 4d bands, constructing the conduction path along the Pd-O layer in PbPdO2. Pd deficiency in PbPdO2 causes decreased O 2p-Pd 4d and increased O 2p-Pb 6p hybridizations, thereby inducing a small band gap and hence reducing conductivity. Hall measurements indicate that PbPdO2 is a p-type gapless semiconductor with intrinsic hole carriers transporting in the Pd-O layers.

The present study investigated the neurotoxic effects of repeated MPTP injections on monoamine neurotransmitters and locomotor activity in rats of different ages. We also examined the mortality of MPTP-treated rats at different ages. Male Sprague-Dawley rats were used in all experiments. In the first experiment, we examined the mortality of rats (11-12 month old) subject to different doses of MPTP. In the second experiment, rats of 2-3 months old were randomly divided into five groups. Group 1 served as the control; Groups 2,3,4 and 5 received daily MPTP injections (30 mg/kg, ip) for a continuation of 7 days. Biochemical and behavioral assays were conducted at 1,7,14 and 28 days after withdrawal of MPTP, respectively. In the third and fourth experiments, the same experimental design was adopted except that rats of 5-6 months old and rats of 11-12 months old were used, respectively. Besides, the doses of MPTP used were 22.5 mg/kg and 12.5 mg/kg, respectively. Immunohistochemical experiments were always conducted 7 days after withdrawal of MPTP. Results indicated that, in young rats, repeated MPTP injections did not significantly decrease DA, and 5HT levels as well as TH and DBH immunoreactivities although it impaired locomotor activity. The same treatment significantly depleted DA, NE and 5HT levels in the middle-aged rats. It also decreased the density of TH and DBH immunoreactivities and altered the morphology of DA and NE neurons. Meanwhile, it impaired locomotor activity. In old rats, MPTP injections produced effects similar to those observed in the middle-age rats except that the hippocampal serotonergic system was also affected. However, all these effects recovered 28 days after withdrawal of MPTP injection. Finally, the dose of MPTP required to exert similar extent of neurotoxicity decreased as the age of rats increased, and the dose required to result in mortality markedly decreased in old rats. These results together suggest that MPTP does exert a toxicity on DA, NE and 5HT neurons and impair motor activity in rats. These effects are age-dependent while the irreversibility of MPTP's toxicity in rats requires further investigation.

O K- and Mn L2,3-edges x-ray absorption spectra of orthorhombic TbMnO3 single crystals show strong polarization dependence, in contrast with results of previous experiments on orthorhombic LaMnO3 and DyMnO3 thin films that show nearly isotropic spectral structure. First-principles calculations reveal that TbMnO3 exhibits a zigzag eg orbital ordering ground state. The highly distorted MnO6 octahedron and orbital ordering in TbMnO3 produce highly anisotropic Mn–O bonding within the ab plane, a frustration of the magnetic ordering, and the formation of complicated incommensurate magnetic structures.

The state-selective dissociation dynamics for anionic and excited neutral fragments of gaseous SiCl4 following Cl 2p and Si 2p core-level excitations were characterized by combining measurements of the photon-induced anionic dissociation, x-ray absorption and UV/visible dispersed fluorescence. The transitions of core electrons to high Rydberg states/doubly excited states in the vicinity of both Si 2p and Cl 2p ionization thresholds of gaseous SiCl4 lead to a remarkably enhanced production of anionic, Si− and Cl−, fragments and excited neutral atomic, Si*, fragments. This enhancement via core-level excitation near the ionization threshold of gaseous SiCl4 is explained in terms of the contributions from the Auger decay of doubly excited states, shake-modified resonant Auger decay, or/and post-collision interaction. These complementary results provide insight into the state-selective anionic and excited neutral fragmentation of gaseous molecules via core-level excitation.

The state-selective dissociation pathways for ionic and excited neutral fragments of gaseous and condensed CCl4 following Cl?2p core-level excitation have been characterized by combining photon-induced ionic dissociation, x-ray absorption, resonant photoemission and UV/visible dispersed fluorescence measurements. The excitation of CCl4 induces significant enhancement of the Cl+ desorption yield in the condensed phase and the CCl+ yields in the gaseous phase. Based on the resonant photoemission studies, excitations of Cl?2p electrons to valence orbitals and Rydberg states decay predominantly via the spectator Auger transitions. The transitions of Cl?2p electrons to the Rydberg state of gaseous CCl4 lead to a noteworthy production of excited atomic neutral fragments (C*) and excited diatomic neutral fragments (CCl*). These results provide insight into the state-selective ionic and neutral fragmentation processes of molecules via core-level excitation.

Efficient VUV generation near 160 nm has been demonstrated in Mg vapor at pressures between .1 -1. Torr and an estimated laser intensity of 10 W/cm2 The highest efficiency measured is on the order of .1 % and it is found that the vUv generation scales as P35 j the above pressure range. The data indicate that stimulated emission from molecular Mg plays an important role.© (1990) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The Mn 3d valence states in single-crystalline TbMnO3 were probed using x-ray absorption spectroscopy and resonant x-ray emission spectroscopy (RXES). The polarized Mn K-edge x-ray absorption spectra show a strong polarization dependence, particularly for the white line region, indicating the strong anisotropic Mn–O bonding within the ab plane in TbMnO3. The RXES data obtained at the Mn K edge clearly reveal that unoccupied Mn 3d states exhibit a relatively delocalized character, stemming from hybridization of the Mn 3d states with the neighboring Mn 4p orbitals. The authors demonstrated that resonant x-ray emission spectroscopy is able to characterize the degree of localization of the unoccupied states or hole carriers in manganites.

The state-selective positive-ion and negative-ion dissociation pathways of gaseous and condensed Si(CH(3))(2)Cl(2) following Cl 2p, Cl 1s, and Si 2p core-level excitations have been characterized. The excitations to a specific antibonding state (15a(1) (*) state) of gaseous Si(CH(3))(2)Cl(2) at the Cl 2p, Cl 1s, and Si 2p edges produce significant enhancement of fragment ions. This ion enhancement at specific core-excited states correlates closely with the ion kinetic energy distribution. The results deduced from ion kinetic energy distribution are consistent with results of quantum-chemical calculations on Si(CH(3))(2)Cl(2) using the ADF package. The Cl(-) desorption yields for Si(CH(3))(2)Cl(2)Si(100) at approximately 90 K are notably enhanced at the 15a(1) (*) resonance at both Cl 2p and Si 2p edges. The resonant enhancement of Cl(-) yield occurs through the formation of highly excited states of the adsorbed molecules. These results provide insight into the state-selective ionic fragmentation of molecules via core-level excitation.

We have probed the distribution of hole carriers in Eu(Ba1−xEux)2 Cu3O7+δ (x = 0-0.2) and Eu(Ba1−xPrx)2Cu3O7+δ (x = 0-0.25) by O K-edge and Cu L-edge x-ray absorption spectra. Upon Eu and Pr substitution at the Ba site in Eu(Ba1−xRx)2Cu3O7+δ, the concentration of holes in the CuO2 planes becomes greatly diminished. The depletion rate of hole carriers within the CuO2 planes in Eu(Ba1−xPrx)2Cu3O7+δ is greater than that in Eu(Ba1−xEux)2Cu3O7+δ. The rate of Tc suppression with Pr doping in Eu(Ba1−xPrx)2Cu3O7+δ is accordingly greater than that in Eu(Ba1−xEux)2Cu3O7+δ.

Non-resonant multiphoton ionization of atomic lead at 1064nm laser field has been studied. Both the angular distribution and the intensity dependence of photoelectrons have been measured. The results show that they are very sensitive to the process of multiphoton ionization.

In an odd isotope with nuclear spin I not=O of an atom, the sublevels usually degenerate at certain points in energy ordinate which they call crossings. In alkaline-earth atoms, there is a series of crossings and it is determined only by the hyperfine splitting of the first ionisation limit ms 2S12/. A formula which is used to calculate the crossings has been derived. By using this formula, the framework of the sublevels and the experimental profile can be anticipated without knowing any detailed information about the odd isotope except for the hyperfine splitting of the first ionisation limit ms 2S12/.

The MQDT of hyperfine structure is greatly simplified in extremely high Rydberg states. A four (or three)-channel quantum defect model is derived for the hyperfine structure of extremely high Rydberg states of msnd configuration in odd alkaline-earth isotopes, in which the transformation matrix Ui(F)i' is given analytically except for one parameter which measures the mixing of singlet 1D2 and triple 3D2 induced by spin-orbit interaction in even isotopes, and in which the four eigen quantum defects mu i' (i'=1, 2, 3, 4) are related to the quantum defects of the fine structure in even isotopes by mu i'=mod( delta i'). This model has been used to interpret the observed sublevel structure of 5snd (n>100) configurations in 87Sr. An excellent agreement between the theoretical and experimental results was achieved.

A two-channel quantum defect model is applied to analyse the strongly perturbed principal absorption series of Sr near threshold. Experimental data in the discrete and in the autoionization region are expressed in terms of five parameters: two eigenquantum defects μ α , one transformation angle θ , and two dipole matrix elements D α . Values of the parameters, obtained by fitting the experimental data, provide information on the mixing coefficients of the levels and oscillator strength as well as on photoabsorption cross sections in the autoionization region. The two-channel model is sufficient to describe the discrete spectrum. Discrepancies show up between theory and experiment in the autoionization region because of opening up of additional channels above the first ionization threshold.

Mechanisms of the excitation, transformation, and decay of atomic and molecular Rydberg states are described and unsettled questions are discussed.

Rydberg spectra of the chlorine atom 3s/sup 2/3p/sup 4/( /sup 3/P)ns, J = (1/2), (3/2), and (5/2), are calculated by use of an eigenchannel quantum-defect method. The results indicate that the channel interactions due to electrostatic and spin-orbit potentials are weak. The effect due to channel interaction of the 3s3p/sup 6/ configuration is completely negligible. Agreement with emission data is excellent (< or approx. =0.2% accuracy except for the lowest n = 4 levels). Autoionization resonances are predicted.

The collision-induced two-photon forbidden 3s2 1S-3snp 1P transitions (n>11) and collisional enhancement of 3s2 1S-3sns 1S transitions (n>8) of Mg I have been observed and studied as functions of Mg vapour pressure and perturbing gas (Ar) pressure by using two-photon resonant ionisation and thermionic diode techniques. The occurrence of forbidden transitions and collisional enhancement of 3s2 1S-3sns 1S transitions is qualitatively attributed to the formation of a Rydberg Mg2 excimer and a MgxAry Fermi complex. Quantitatively, the above phenomena are interpreted as collisional mixing of high Rydberg states of Mg. The mixing coefficients are estimated by using perturbation theory and the semiclassical (JWKB) approximation. The theoretical estimation is in good agreement with the experimental result.

We report a calculation of the basic structure parameters of 3${p}^{4}$${(}^{3}$P)ns Rydberg spectra of the chlorine isoelectronic ions from Ar ii to Zn xiv as functions of effective nuclear charge by using the eigenchannel quantum-defect theory. The results indicate that the channel interaction gradually diminishes along the isoelectronic sequence. This behavior can be interpreted as the competition between electrostatic and spin-orbit interactions along the sequence. A great amount of basic atomic data can be evaluated with these parameters as input.