Theoretical study of ultrafast x-ray photoelectron diffraction from molecules undergoing photodissociation.

We present a new theoretical work for the ultrafast x-ray photoelectron diffraction (UXPD) method to track photodissociation of molecules over the long range in femtosecond time scale. Our theory combines the accurate multicenter description of XPD at short to medium distances and the multiple-scattering XPD approach at larger internuclear separations. Then, the theoretical framework is applied to a demonstration of the UXPD profiles from halogen diatomics undergoing photodissociation. The computational results indicate that such a combination of the two theoretical approaches sufficiently works to seamlessly track the conformational evolution during photodissociation. The present study provides information on dissociation kinetics of neutral diatomic molecules available with the UXPD method and is a step towards an approach applied to general photoelimination processes.

Multinodular and vacuolating neuronal tumor affecting amygdala and hippocampus: A quasi-tumor?

Multinodular and vacuolating neuronal tumors (MVNT) have been referred to as distinctive neuronal tumors whose characteristic features include multiple nodules localized in the subcortical white matter. MVNT are composed of vacuolating dysplastic neurons reactive to HuC/HuD. A significant overexpression of alpha-internexin (INA) limited to the stroma of nodules was reported in one tumor. Since genetic analyses have failed to demonstrate any consistent alterations, the nosological position as well as the nature of MVNT, namely, neoplastic or dysplastic, remains unclear. We herein present another example of MVNT involving the amygdala and anterior hippocampus in a 41-year-old man. In addition to the nodular lesions described earlier, we found INA-positive ribbon-like lesions that replaced neuropil and extended along the hippocampal gray matter. We also identified dysplastic neurons infiltrating into the CA4 hilus of the hippocampus. Intense INA expression was present in the stroma as well as the cytoplasmic membrane of dysplastic neurons and their processes. While the invasiveness suggested a neoplasm, a relatively restrictive, either nodular or ribbon-like growth pattern with INA-positive abnormal neuropil suggested a hamartoma. Such quasi-tumors should be accommodated in the World Health Organization classification of tumors of the central nervous system, as are dysembryoplastic neuroepithelial tumor and Lhermitte-Duclos disease.

Clinical and neuroimaging review of monogenic cerebral small vessel disease from the prenatal to adolescent developmental stage.

Cerebral small vessel disease (cSVD) refers to a group of pathological processes with various etiologies affecting the small vessels of the brain. Most cases are sporadic, with age-related and hypertension-related sSVD and cerebral amyloid angiopathy being the most prevalent forms. Monogenic cSVD accounts for up to 5% of causes of stroke. Several causative genes have been identified. Sporadic cSVD has been widely studied whereas monogenic cSVD is still poorly characterized and understood. The majority of cases of both the sporadic and monogenic types, including cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), typically have their onset in adulthood. Types of cSVD with infantile and childhood onset are rare, and their diagnosis is often challenging. The present review discusses the clinical and neuroimaging findings of monogenic cSVD from the prenatal to adolescent period of development. Early diagnosis is crucial to enabling timely interventions and family counseling.

Asymmetrical putaminal atrophy in parkinsonism-predominant multiple system atrophy (MSA-P): A case report.

We encountered a case of multiple system atrophy parkinsonian subtype (MSA-P) with right-dominant parkinsonism in the early stage of the disease. Atrophy of the posterolateral putamen and iron deposition are the neuropathological hallmark of MSA-P. Coronal fluid-attenuated inversion-recovery (FLAIR) images showed atrophy and iron deposition in the left posterior putamen contralateral to the clinical dominant side in the early phase. Atrophy in the posterior putamen of patients with MSA-P was more clearly observed on coronal FLAIR images than on axial T2-weighted images. These findings reflected the pathological changes and might be a pathognomonic sign of MSA-P.

Neuroimaging findings of inborn errors of metabolism: urea cycle disorders, aminoacidopathies, and organic acidopathies.

Although there are many types of inborn errors of metabolism (IEMs) affecting the central nervous system, also referred to as neurometabolic disorders, individual cases are rare, and their diagnosis is often challenging. However, early diagnosis is mandatory to initiate therapy and prevent permanent long-term neurological impairment or death. The clinical course of IEMs is very diverse, with some diseases progressing to acute encephalopathy following infection or fasting while others lead to subacute or slowly progressive encephalopathy. The diagnosis of IEMs relies on biochemical and genetic tests, but neuroimaging studies also provide important clues to the correct diagnosis and enable the conditions to be distinguished from other, more common causes of encephalopathy, such as hypoxia-ischemia. Proton magnetic resonance spectroscopy (1H-MRS) is a powerful, non-invasive method of assessing neurological abnormalities at the microscopic level and can measure in vivo brain metabolites. The present review discusses neuroimaging findings, including those of 1H-MRS, of IEMs focusing on intoxication disorders such as urea cycle disorders, aminoacidopathies, and organic acidopathies, which can result in acute life-threatening metabolic decompensation or crisis.

Formation and oxidation mechanisms of Pd-Zn nanoparticles on a ZnO supported Pd catalyst studied by in situ time-resolved QXAFS and DXAFS.

Formation and oxidation processes of PdZn nanoparticles on ZnO were successfully observed by means of in situ time-resolved X-ray absorption fine structure spectroscopy (XAFS), and the analysis of data on near-edge (XANES) and extended (EXAFS) structures revealed detailed changes in Pd during both processes. PdZn nanoparticles were formed on ZnO through a two-step scheme under a hydrogen atmosphere. The first process was the formation of metallic Pd nanoparticles, which was quickly finished within 1 s. The second process was the formation of PdZn nanoparticles, which took several tens of minutes. Oxidation of the PdZn nanoparticles also consisted of two processes. Zn atoms were oxidized prior to Pd atoms and the metallic Pd nanoparticles surrounded by ZnO were formed afterwards. Oxidation of the metallic Pd nanoparticles was scarce and very slow. According to the results of kinetic analyses, the metallic Pd surrounded by ZnO was a stable species under the oxidative atmosphere.

Imaging findings and pathological correlations of subacute encephalopathy with neuronal intranuclear inclusion disease-Case report.

Neuronal intranuclear inclusion disease (NIID) is a slowly progressive neurodegenerative disease and may sometimes present with symptoms of subacute encephalopathy, including fever, headache, vomiting, and loss of consciousness. We present a case of adult-onset NIID with subacute encephalopathy, which is confirmed by skin and brain biopsied. The magnetic resonance imaging findings show cortical swelling and hyperintensities in the right temporooccipital lobes on T2-weighted images and magnetic resonance angiography demonstrates vasodilatations of the right middle cerebral artery and posterior cerebral artery. Abnormal enhancement is mainly observed in the gyral crowns (crown enhancement). Pathological examinations reveal new infarcts in the deep layers of the cortices. NIID should be considered in the presence of subacute encephalopathy with cortical swelling, contrast enhancement in the temporooccipital lobes, and vasodilation in adult patients. The encephalopathy targeted on the cortices, and the pathological background included infarctions.

Extreme ultraviolet free electron laser seeded with high-order harmonic of Ti:sapphire laser.

The 13th harmonic of a Ti:sapphire (Ti:S) laser in the plateau region was injected as a seeding source to a 250-MeV free-electron-laser (FEL) amplifier. When the amplification conditions were fulfilled, strong enhancement of the radiation intensity by a factor of 650 was observed. The random and uncontrollable spikes, which appeared in the spectra of the Self-Amplified Spontaneous Emission (SASE) based FEL radiation without the seeding source, were found to be suppressed drastically to form to a narrow-band, single peak profile at 61.2 nm. The properties of the seeded FEL radiation were well reproduced by numerical simulations. We discuss the future precept of the seeded FEL scheme to the shorter wavelength region.

O1s photoionization dynamics in oriented NO2.

We have performed extensive density functional theory (DFT) calculations, partial cross sections, dipole prepared continuum orbitals, dipole amplitudes and phase shifts, asymmetry parameters ß, and molecular frame photoelectron angular distributions, to elucidate the O1s photoionization dynamics of NO(2) molecule with emphasis on the shape resonances in the O1s ionization continuum. In the shape resonance region, the ß parameters and photoelectron angular distributions have been compared with our experimental results. Fairly good agreement between the theory and experiment has confirmed that the DFT level calculations can well describe the photoionization dynamics of the simple molecule such as NO(2). Interference due to equivalent atom photoionization is theoretically considered, and the possibility of detection of the effect in the two degenerate channels with different combinations of light polarization and photoemission direction is discussed.

[Definitions and MR imaging of duropathies].

Kumar defined duropathies as disorders with dural defects-related cerebrospinal fluid leaks, particularly of spinal anterior dura mater, Superficial (hemo) siderosis (SS) and multisegemental amyotrophy (MSAM) were included in duropathies. Dural defects of SS had two types; one was incomplete closure of the dura in the spinal and cranial operations, the other was a spontaneous defect in the spinal anterior dura mater. In a majority of SS patients, spontaneous dural defects were detected at the levels of C7/Th1 to Th2/Th3 on axial FIESTA (fast imaging employing steady state acquisition) images. Similarly, dural defects in our 6 cases with MSAM were showed at C7/Th1 to Th2/Th3. Axial FIESTA images were crucial on MR imaging. T2 weighted images demonstrated abnormal hyperintense lesions in both anterior horns at the level of C3 spinal cord in all of 7 patients with MSAM. A dural defect in one case was not found.

N 1s photoelectron angular distributions from fixed-in-space NO2 molecules: stereodynamics and symmetry considerations.

Angular distributions of N 1s photoelectrons from fixed-in-space NO(2) molecules have been measured over the energy region of shape resonance and above. A multiple-coincidence velocity-map imaging technique for observation of molecular frame photoelectron angular distributions (MF-PADs) has been extended to nonlinear molecular targets. Density functional theory calculations have also been conducted to elucidate the photoionization dynamics and shape resonance in the N 1s photoionization of NO(2). Results show that the N 1s MF-PADs exhibit strong shape variation as a function of both photoelectron kinetic energy and symmetries of final states, whereas asymmetry parameters of laboratory frame PADs show a local minimum around the shape resonance region and increase monotonically as the photon energy increases. Over the shape resonance, the spatial shape of the photoelectron wave function with b(2)-symmetry closely resembles that of 5b(2)(∗) unoccupied molecular orbital of NO(2), although the MF-PAD pattern for b(2)-symmetry does not correspond directly to the 5b(2)(∗) orbital shape. At higher kinetic energy of 90 eV, MF-PADs become less structured, but still show a significant dependence on the symmetry of final states.

Clinical and imaging characteristics of localized megalencephaly: a retrospective comparison of diffuse hemimegalencephaly and multilobar cortical dysplasia.

INTRODUCTION: Hemimegalencephaly is a well-known congenital malformation. However, localized megalencephaly, which may be one of the subtypes of hemimegalencephaly, has not been separately investigated. In the present study, we attempted to characterize the clinical and magnetic resonance (MR) imaging features of localized megalencephaly in comparison with ordinary diffuse hemimegalencephaly and multilobar cortical dysplasia. METHODS: MR findings for 43 patients with hemimegalencephaly and ten with multilobar cortical dysplasia, which is the differential diagnosis of localized megalencephaly, were retrospectively reviewed. Clinical findings such as the onset and severity of seizures and imaging findings including the affected area of the brain, structures outside of the hemisphere, and interval morphological changes were examined. RESULTS: Of the 43 patients, 11 showed signs of localized megalencephaly (25.6%). Localized megalencephaly was predominantly seen on the left side (72.7%) and had a tendency toward severe-grade seizures compared to multilobar cortical dysplasia. The frequencies of the extracerebral abnormalities in the diffuse hemimegalencephaly, localized megalencephaly, and multilobar cortical dysplasia groups were 84.4%, 36.4%, and 0.0%, respectively. There were three localized megalencephaly patients whose affected areas shrank and whose images were similar to those of multilobar cortical dysplasia. CONCLUSION: Localized megalencephaly accounts for one quarter of all hemimegalencephaly cases in this study. The incidence of extracerebral abnormalities in patients with localized hemimegalencephaly was almost half that of patients with diffuse hemimegalencephaly. Extracerebral abnormalities were absent in patients with multilobar cortical dysplasia. Associated extracerebral abnormalities may be a clue to differentiating localized megalencephaly from multilobar cortical dysplasia.

[The presyrinx state due to adhesive arachnoiditis: a case report].

We report a 66-year-old woman with a presyrinx state due to adhesive arachnoiditis. She had a history of subarachnoid hemorrhage one year ago. She became aware of gait disturbance and abnormal sensation at the chest 6 months ago. Neurological examination revealed weakness of the both lower extremities and sensory disturbance below the T6 level. MR images of the thoracic spine revealed swelling of the thoracic cord at the T3-4 level, with an intramedullary hyperintensity on T2 weighted images (WI) and hypointensity on T1-WI. The intramedullary hypointensity on T1-WI was less than the CSF intensity. In addition, the thoracic cord lower than T5 level was compressed by an arachnoid cyst in the spinal canal. The preoperative diagnosis was the presyrinx state due to adhesive arachnoiditis. An operation for detachment of arachnoidal adhesion and restoration of CSF flow pathway was performed. After one month from the operation, neurological findings were improved. Postoperative MR images revealed improvement of swelling of the thoracic cord and intramedullary abnormal intensity. The arachnoid cyst in the spinal canal was decreased in the size. The presyrinx state is recently recognized condition before the formation of syringomyelia and that is known to resolve with proper treatment. We wish to emphasize we could prevent a progression to syringomyelia by a proper treatment for the presyrinx state.

Observation of a shape resonance of the positronium negative ion.

When an electron binds to its anti-matter counterpart, the positron, it forms the exotic atom positronium (Ps). Ps can further bind to another electron to form the positronium negative ion, Ps(-) (e(-)e(+)e(-)). Since its constituents are solely point-like particles with the same mass, this system provides an excellent testing ground for the three-body problem in quantum mechanics. While theoretical works on its energy level and dynamics have been performed extensively, experimental investigations of its characteristics have been hampered by the weak ion yield and short annihilation lifetime. Here we report on the laser spectroscopy study of Ps(-), using a source of efficiently produced ions, generated from the bombardment of slow positrons onto a Na-coated W surface. A strong shape resonance of (1)P(o) symmetry has been observed near the Ps (n=2) formation threshold. The resonance energy and width measured are in good agreement with the result of three-body calculations.

Structure determination of molecules in an alignment laser field by femtosecond photoelectron diffraction using an X-ray free-electron laser.

We have successfully determined the internuclear distance of I2 molecules in an alignment laser field by applying our molecular structure determination methodology to an I 2p X-ray photoelectron diffraction profile observed with femtosecond X-ray free electron laser pulses. Using this methodology, we have found that the internuclear distance of the sample I2 molecules in an alignment Nd:YAG laser field of 6 × 1011 W/cm2 is elongated by from 0.18 to 0.30 Å "in average" relatively to the equilibrium internuclear distance of 2.666 Å. Thus, the present experiment constitutes a critical step towards the goal of femtosecond imaging of chemical reactions and opens a new direction for the study of ultrafast chemical reaction in the gas phase.

Photoelectron diffraction from laser-aligned molecules with X-ray free-electron laser pulses.

We report on the measurement of deep inner-shell 2p X-ray photoelectron diffraction (XPD) patterns from laser-aligned I2 molecules using X-ray free-electron laser (XFEL) pulses. The XPD patterns of the I2 molecules, aligned parallel to the polarization vector of the XFEL, were well matched with our theoretical calculations. Further, we propose a criterion for applying our molecular-structure-determination methodology to the experimental XPD data. In turn, we have demonstrated that this approach is a significant step toward the time-resolved imaging of molecular structures.

Clinical outcomes after corpus callosotomy in patients with bihemispheric malformations of cortical development.

OBJECT: Epilepsy in patients with bihemispheric malformations of cortical development (MCD) is typically medically intractable. Focal resection has been reported to be ineffective. Corpus callosotomy has been advocated as a treatment option, but the results have been reported only in several case reports. The authors describe a series of 10 patients with bihemispheric MCDs who underwent total corpus callosotomy. METHODS: The MCDs in these patients included lissencephaly, band heterotopia, perisylvian polymicrogyria, and tuberous sclerosis. Preoperatively all patients suffered disabling drop attacks or intense head drop seizures that caused frequent physical injuries. The follow-up period ranged from 1.4 to 5.8 years (median 3.2 years). Seizure outcome, parental assessment of daily function, and parental satisfaction with outcome were assessed postoperatively. Drop attacks disappeared completely during the entire follow-up period in eight patients and decreased to less than 10% of baseline in one. Other types of seizures were resolved completely in one patient and decreased in seven. Overall daily function improved and parents were satisfied with the surgery-related results in all patients except one who experienced a recurrence of drop attacks. There were no signs of significant and persistent neurological deficits in any case. CONCLUSIONS: Results of total corpus callosotomy in patients with bihemispheric MCDs were favorable in most cases. The procedure was particularly effective against drop attacks causing physical injuries and impaired quality of life in these patients.

Thalamic lesions in a long-surviving child with spinal muscular atrophy type I: MRI and EEG findings.

Brain magnetic resonance imaging was conducted in a girl with genetically confirmed spinal muscular atrophy (SMA) type I. This patient has survived 6 years, to date, under mechanical ventilation. T2-weighted and fluid-attenuated inversion recovery images revealed high signal intensity lesions in the anterolateral portions of the bilateral thalami. Electroencephalography disclosed diffuse beta activity upon awakening and during light sleep. In addition, fast and prolonged spindles were observed. Although mild neuronal changes in the lateral nucleus of the thalamus have been described in several autopsied cases, this is the first study to demonstrate neuroradiologically and neurophysiologically the thalamic lesions in genetically confirmed SMA type I.

[Progress in MR imaging: differential diagnosis of infectious and inflammatory diseases with MR imaging].

MR imaging is useful for diagnosis of infectious and inflammatory diseases. Diffusion weighted images (DWI) and fluid-attenuated inversion recovery (FLAIR) images revealed hyperintense signal changes in the anterior striata and cortices in patients with Creutzfeldt-Jakob disease, which were characteristic. In patients with nonherpetic and non-paraneoplastic acute limbic encephalitis, DWI and FLAIR images showed hyperintense changes in the hippocampi, amygdales, cingulate gyri, and occasionally claustrum, but not in the anterior and lateral temporal cortices, which were often involved in herpes simplex encephalitis. In ventriculitis, DWI and FLAIR images showed high signal intensity changes with niveau formation in the lateral ventricle, which indicated the presence of pus in the ventricle. In Japanese encephalitis, T2-weighted images showed high signal intensity changes in the thalami and substantia nigra, which were most often involved by Japanese encephalitis. In idiopathic cranial hypertrophic pachymeningitis, thallium-201 SPECT showed a remarkable accumulation in the abnormal dura matter. Furthermore, the abnormal uptake of thallium-201 returned to normal after treatment with corticosteroid. Thallium-201 SEPCT was useful for the evaluation of disease activity in patients with hypertrophic cranial pachymeningitis.