Off-resonance photoemission dynamics studied by recoil frame F1s and C1s photoelectron angular distributions of CH3F.

F1s and C1s photoelectron angular distributions are considered for CH3F, a molecule which does not support any shape resonance. In spite of the absence of features in the photoionization cross section profile, the recoil frame photoelectron angular distributions (RFPADs) exhibits dramatic changes depending on both the photoelectron energy and polarization geometry. Time-dependent density functional theory calculations are also given to rationalize the photoionization dynamics. The RFPADs have been compared with the theoretical calculations, in order to assess the accuracy of the theoretical method and rationalize the experimental findings. The effect of finite acceptance angles for both ionic fragments and photoelectrons has been included in the calculations, as well as the effect of rotational averaging around the fragmentation axis. Excellent agreement between theory and experiment is obtained, confirming the good quality of the calculated dynamical quantities (dipole moments and phase shifts).

Angular correlation between B K-VV Auger electrons of BF3 molecules and coincident fragment ions: manifestation of the difference between the angular correlation and molecular frame Auger electron angular distribution.

We have measured the angular correlation between the B K-VV Auger electrons of BF(3) molecules and the coincident fragment-ion pairs of BF(2)(+)-F(+). Then, we have found that the measured angular correlation patterns depending on the mutual angle between the light polarization direction and molecular orientation are affected by the anisotropic axis distribution of the molecular ensemble of BF(3)(+) reflecting the anisotropic nature of photon-molecule interaction. In this context, we have pointed out generally that for coincidence experiments, so-called molecular frame Auger electron angular distributions are realized only if the axis distribution of the molecular ion ensemble is isotropic.

Radial incision and cutting method for refractory stricture after nonsurgical treatment of esophageal cancer.

Strictures remaining after nonsurgical treatment for esophageal cancer are generally more refractory to endoscopic balloon dilation (EBD) when compared with anastomotic strictures. The aim of the present study was to evaluate the efficacy and safety of a radial incision and cutting (RIC) method for the treatment of refractory strictures after nonsurgical treatment of esophageal cancer. All subjects complained of grade 2 or worse dysphagia, even after at least 10 sessions of EBD. Between August 2009 and May 2012, eight consecutive patients with refractory esophageal stricture after nonsurgical treatments, including chemoradiotherapy (CRT) alone (n = 3), CRT followed by salvage endoscopic treatment (n = 3), or endoscopic submucosal dissection (ESD; n = 2), underwent the RIC procedure. After the RIC procedure, dysphagia in all the patients dramatically improved to grade 1 or 0 without any major complications; however, the long-term efficacy was unfavorable as only 37.5 % (3 /8) demonstrated adequate lumen patency at 3 months, and re-intervention was necessary in six patients (75 %).

Recoil frame photoelectron angular distributions of BF3: a sensitive probe of the shape resonance in the F 1s continuum.

Recoil frame photoelectron angular distributions (RFPADs) of BF(3) molecules are presented over the energy region of the shape resonance in the F 1s continuum. Time-dependent density functional theory calculations are also given to understand the shape resonance dynamics. The RFPADs have been compared with the theoretical calculations. It is found that the RFPADs calculated by the localized core-hole model are in better agreement with the experimental, compared with those by the delocalized core hole. Dipole matrix elements and dipole prepared continuum wavefunctions show that the shape resonance in the F 1s ionization continuum of BF(3) is induced by p-partial waves as previously reported by Swanson et al. [J. Chem. Phys. 75, 619 (1981)]. However, due to the couplings with the other partial waves the feature characteristic of the p-partial waves has not been observed in the RFPADs.

Basic studies toward ultrafast soft x-ray photoelectron diffraction; its application to probing local structure in iodobenzene molecules.

Ultrafast x-ray photoelectron diffraction (UXPD) for free molecules has a promising potential to probe the local structures of the molecules in an element-specific fashion. Our UXPD scheme consists of three steps: (1) near-infrared laser (NIR) with ns pulse duration aligns sample molecules, (2) ultra-violet laser with fs pulse duration pumps the aligned molecules, and (3) soft x-ray free-electron laser (SXFEL) with fs pulse duration probes the molecules by measuring x-ray photoelectron diffraction (XPD) profiles. Employing steps of (1) and (3), we have measured I 3d XPD profiles from ground state iodobenzene aligned by the NIR laser with the SXFEL. Then, we have intensively calculated I 3d XPD profiles with density functional theory, taking degrees of alignments of the molecules into account, to extract a distance between C and I atoms in iodobenzene from the experimental I 3d XPD profiles. Although we have failed to determine the distance from the comparison between the experimental and theoretical results, we have succeeded in concluding that the degeneracies of the initial state eliminate the sensitivity on molecular structure in the I 3d XPD profiles. Thus, the observation of fine structures in the XPD profiles could be expected, if a nondegenerate molecular orbital is selected for a probe of UXPD. Finally, we have summarized our criteria to perform UXPD successfully: (1) to use SXFEL, (2) to prepare sample molecules with the degree of alignment higher than 0.8, and (3) to select a photoemission process from a nondegenerate inner-shell orbital of sample molecules.

Photodetachment of positronium negative ions.

Photodetachment of the positronium negative ion, a bound state of one positron and two electrons, has been observed. Development of a method to produce the ions efficiently using a Na coated tungsten surface has enabled the first observation of the photodetachment. The obtained lower limit of the photodetachment cross section for the wavelength of 1064 nm is consistent with the theoretical calculations reported so far. The experimental field developed in the present work gives new opportunities to explore the quantum mechanical three-body problem and to develop energy-tunable positronium beams.

In situ time-resolved XAFS study on the structural transformation and phase separation of Pt3Sn and PtSn alloy nanoparticles on carbon in the oxidation process.

The dynamic behavior and kinetics of the structural transformation of supported bimetallic nanoparticle catalysts with synergistic functions in the oxidation process are fundamental issues to understand their unique catalytic properties as well as to regulate the catalytic capability of alloy nanoparticles. The phase separation and structural transformation of Pt(3)Sn/C and PtSn/C catalysts during the oxidation process were characterized by in situ time-resolved energy-dispersive XAFS (DXAFS) and quick XAFS (QXAFS) techniques, which are element-selective spectroscopies, at the Pt L(III)-edge and the Sn K-edge. The time-resolved XAFS techniques provided the kinetics of the change in structures and oxidation states of the bimetallic nanoparticles on carbon surfaces. The kinetic parameters and mechanisms for the oxidation of the Pt(3)Sn/C and PtSn/C catalysts were determined by time-resolved XAFS techniques. The oxidation of Pt to PtO in Pt(3)Sn/C proceeded via two successive processes, while the oxidation of Sn to SnO(2) in Pt(3)Sn/C proceeded as a one step process. The rate constant for the fast Pt oxidation, which was completed in 3 s at 573 K, was the same as that for the Sn oxidation, and the following slow Pt oxidation rate was one fifth of that for the first Pt oxidation process. The rate constant and activation energy for the Sn oxidation in PtSn/C were similar to those for the Sn oxidation in Pt(3)Sn/C. In the PtSn/C, however, it was hard for Pt oxidation to PtO to proceed at 573 K, where Pt oxidation was strongly affected by the quantity of Sn in the alloy nanoparticles due to swift segregation of SnO(2) nanoparticles/layers on the Pt nanoparticles. The mechanisms for the phase separation and structure transformation in the Pt(3)Sn/C and PtSn/C catalysts are also discussed on the basis of the structural kinetics of the catalysts themselves determined by the in situ time-resolved DXAFS and QXAFS.

Dissociation dynamics of C(6)H(6) and C(6)H(5)F molecules following carbon 1s and fluorine 1s photoionization studied by three-dimensional momentum imaging method.

Benzene and fluorobenzene molecules were multiply ionized through Auger decay following from the C 1s or the F 1s photoionization and their subsequent dissociations were studied utilizing position-sensitive time-of-flight measurements. The angular correlation between the momenta of (H(+)-H(+)) and (H(+)-F(+)) fragment ions derived from the multiply ionized benzene or fluorobenzene clearly reflects the hexagonal structure of the parent molecules, though the dissociations are not described by the simple Coulomb explosion model. Also, analysis on the planarity between the momentum of H(+), C(+), and F(+) reveals that these three ions are emitted almost in a single plane.

Symmetric temporal abnormalities on MR imaging in amyotrophic lateral sclerosis with dementia.

BACKGROUND AND PURPOSE: Our aim was to clarify imaging findings of amyotrophic lateral sclerosis with dementia (ALSD). MATERIALS AND METHODS: T2-weighted MR images (T2WI) of 3 patients with ALSD (2 men, 1 woman; 58-71 years of age) and 21 patients with ALS without dementia (12 men, 9 women; 46-74 years of age) were examined for frontotemporal lobar atrophy and signal-intensity alterations in the white matter of the anterior temporal lobes, corticospinal tracts (CST), and precentral gyri and in precentral cortices. The brain of one of the patients with ALSD was examined at autopsy. RESULTS: All patients with ALSD showed bilateral frontotemporal atrophy mostly with temporal lobe dominance. In the ALSD group, T2WI demonstrated hyperintensity in the subcortical white matter on the medial side of the anterior temporal lobes, whereas in the group without dementia, none showed this imaging finding. MR images demonstrated no abnormal signal-intensity changes in CST in the internal capsule or the brain stem in the ALSD group. In the group without dementia, 6 patients (28.6%) showed this imaging finding. In neuropathologic examinations of the brain of 1 patient with ALSD, myelin-stained sections of the brain demonstrated loss of myelin in the subcortical white matter on the medial side of the anterior temporal white matter. CONCLUSIONS: A symmetric pattern of frontotemporal atrophy and anteromedial subcortical hyperintensities in the temporal lobes on T2WI could be characteristic of ALSD.

Hemimegalencephaly: a study of abnormalities occurring outside the involved hemisphere.

BACKGROUND AND PURPOSE: Hemimegalencephaly is a rare but well-known congenital malformation with ipsilateral enlargement of the hemicerebrum. However, very little is known about changes in structures outside the involved hemisphere in patients with this condition. We investigated morphologic abnormalities occurring outside the affected hemisphere by MR imaging in a large series of patients with hemimegalencephaly. MATERIALS AND METHODS: MR imaging findings for 30 patients with hemimegalencephaly were retrospectively reviewed and evaluated for structures outside the involved hemisphere on routine MR images, such as cranial nerves (I, II, V), brain vessels, subdural and subarachnoid spaces, brain stem, and cerebellum, on both the ipsilateral and contralateral sides. RESULTS: The ipsilateral olfactory and optic nerves were enlarged in 8 (26.7%) and 1 (3.3%) of the 30 patients, respectively, without enlargement on the contralateral side. No asymmetry was noted in the trigeminal nerves. Asymmetric vascular dilations in the ipsilateral cerebral hemisphere were observed in 12 of the 30 patients (40%), in deep cerebral vessels in 11 patients (36.7%), and in superficial cerebral vessels in 8 patients (26.7%). Ipsilateral brain stem and hemicerebellar asymmetric enlargement was detected in 2 patients (6.7%) and 14 patients (46.7%), respectively. Abnormal cerebellar folia were observed on the ipsilateral side in 6 patients (20%) and on the contralateral side in 3 patients (10%). CONCLUSION: Ipsilateral olfactory nerve enlargement, cerebral vascular dilations, cerebellar enlargement, and bilateral or ipsilateral abnormal architecture of the cerebellar folia are often associated with hemimegalencephaly.

Pantothenate kinase-associated neurodegeneration with increased lentiform nuclei cerebral blood flow.

We report a case of pantothenate kinase-associated neurodegeneration with increased regional cerebral blood flow (rCBF) in bilateral lentiform nuclei on technetium Tc-99m ethyl cysteinate dimer single-photon emission CT (ECD-SPECT). A 6-year-old boy presented with opisthotonus. T2*-weighted MR images revealed areas of marked hypointensity with a hyperintense focus in bilateral globus pallidus, creating the characteristic eye-of-the-tiger appearance. ECD-SPECT showed increased rCBF in bilateral lentiform nuclei.

Two patients with intraspinal germinoma associated with Klinefelter syndrome: case report and review of the literature.

We report 2 cases of intraspinal germinoma associated with Klinefelter syndrome. In one patient, spinal cord atrophy was observed at the upper and lower ends of the intraspinal tumor. Brain atrophy was observed in both cases. Germinoma should be included in the differential diagnosis if an intraspinal tumor is observed in a patient with Klinefelter syndrome.

Brain SPECT imaging for laminar heterotopia.

Brain perfusion SPECT was performed in an epileptic patient with a rare form of diffuse subcortical laminar heterotopia using 99mTc-HMPAO. MRI demonstrated generalized laminar heterotopia underlying the cortical mantle. Interictal SPECT imaging revealed identical or increased perfusion of the laminar heterotopia as compared with that of the overlying cortical mantle. Moreover, SPECT revealed low perfusion in the left temporal lobe that agreed with the seizure type of complex partial seizures and the EEG finding of frequent generalized spike-wave complexes with a slight left-sided dominance. Brain SPECT imaging may be useful for appropriate diagnosis of gray matter heterotopia and for detection of functionally focal abnormality associated with epilepsy.

Photoelectron angular distributions from O K shell of oriented CO molecules: A critical comparison between theory and experiment

The dynamical information (ten dipole matrix elements and eight phase differences) has been deduced from the measured angular distributions of photoelectrons from O K shell of oriented CO molecules near the ionization threshold in the region of a sigma(*) shape resonance. Light polarization parallel and perpendicular to the molecular axis has been used. An important contribution of six lsigma partial waves with 0

Manifestation of many-electron correlations in photoionization of the K shell of N2

It is demonstrated theoretically in the random phase approximation (RPA) that due to the intershell many-electron correlations the sigma(*) shape resonance in the photoionization of K shells of the N2 molecule appears not only in the 1sigma(g)-->varepsilonsigma(u) channel as it was believed earlier on the basis of single particle calculations, but in both 1sigma(g)-->varepsilonsigma(u) and 1sigma(u)-->varepsilonsigma(g) channels. As a confirmation of this phenomenon we show that the experimental angular distributions of photoelectrons ejected from fixed-in-space N2 molecules can be reproduced theoretically only after taking into account many-electron correlations.

Cerebellar MR in Fukuyama congenital muscular dystrophy: polymicrogyria with cystic lesions.

PURPOSE: To determine the MR appearance of cerebellar abnormalities in Fukuyama congenital muscular dystrophy. METHODS: We reviewed brain MR images of 25 patients with Fukuyama congenital muscular dystrophy and examined the autopsy specimens of a 23-month-old girl with the disease to determine the pathologic nature of the MR findings. RESULTS: MR studies revealed two characteristic cerebellar abnormalities: (a) disorganized cerebellar folia (16 cases) that were recognized as unusual distortions of the cortex; and (b) clusters of intraparenchymal cysts (23 cases). The two lesions were located close to each other, and milder lesions tended to affect only the superior semilunar lobule. The autopsy specimen revealed small cerebellar cysts, which consisted of dilated subarachnoid spaces buried beneath the malformed cortex. CONCLUSION: The disorganized folia represent cerebellar polymicrogyria, and the presence of cerebellar cysts is related to the polymicrogyria. These two MR changes are often present in Fukuyama congenital muscular dystrophy and are distinct enough to suggest the radiologic diagnosis.

Acute encephalopathy with bilateral thalamotegmental involvement in infants and children: imaging and pathology findings.

PURPOSE: To investigate the imaging and pathologic characteristics of acute encephalopathy with bilateral thalamotegmental involvement in infants and children. METHODS: Five Japanese children ranging in age from 11 to 29 months were studied. We performed CT imaging in all patients, 10 MR examinations in four patients, and an autopsy in one patient. RESULTS: The encephalopathy affected the thalami, brain stem tegmenta, and cerebral and cerebellar white matter. The brain of the autopsied case showed fresh necrosis and brain edema without inflammatory cell infiltration. Petechiae and congestion were demonstrated mainly in the thalamus. CT and MR images showed symmetric focal lesions in the same areas in the early phase. These lesions became more demarcated and smaller in the intermediate phase. The ventricles and cortical sulci enlarged. MR images demonstrated T1 shortening in the thalami. The prognosis was generally poor; one patient died, three patients were left with severe sequelae, and only one patient improved. CONCLUSIONS: The encephalopathy might be a postviral or postinfectious brain disorder. T1 shortening in the thalami indicated the presence of petechiae.

Brain MR in Fukuyama congenital muscular dystrophy.

PURPOSE: To determine the MR characteristics of brain abnormalities in Fukuyama congenital muscular dystrophy (FCMD). METHODS: We reviewed 30 MR examinations of 21 patients with FCMD to assess cerebral and cerebellar cortical dysplasia, white matter changes, and miscellaneous abnormalities. RESULTS: On MR images, all patients had thick and bumpy cortices with shallow sulci corresponding to polymicrogyria, and 12 patients had pachygyric cortices with smooth surfaces, corresponding to type II lissencephaly. Both types of cortical dysplasia had characteristic distributions: the first type involved the frontal lobe in all 21 patients and also the parietotemporal lobe in 6 patients; the second type involved the temporooccipital lobes. Eighteen patients had prolonged T1 and T2 signal in the white matter, which was indistinct in neonates and seen infrequently in adolescents. In four patients, abnormal vessels were seen within the pachygyric cortices. CONCLUSION: MR studies of the brain show findings consistent with the known characteristics of FCMD. The MR detection of the two types of cerebral cortical dysplasia with characteristic distribution and cerebellar abnormalities is helpful in the differential and early diagnosis of FCMD.

Involvement of the frontotemporal lobe and limbic system in amyotrophic lateral sclerosis: as assessed by serial computed tomography and magnetic resonance imaging.

The present paper concerns serial examinations of computed tomography (CT) and magnetic resonance imaging (MRI) in 22 patients with sporadic amyotrophic lateral sclerosis (ALS). Supranuclear ophthalmoplegia developed in 13 and dementia in 3 patients. The investigations showed gradually progressive atrophy, first in the frontal and anterior temporal lobes then in the precentral gyrus, and later in the postcentral gyrus, anterior part of the cingulate gyrus, corpus callosum and brain stem tegmentum. MRI revealed high intensity signals on T2-weighted images in the precentral and adjacent gyri, frontotemporal white matter and pyramidal tract as well as rarely in the globus pallidus and thalamus. These neuroradiological changes were not related to the duration of the clinical course or to the degree of the motor impairment. These alterations may play a critical role in the supranuclear ophthalmoplegia seen in ALS patients. The dementia of ALS probably reflects involvement of both the frontotemporal lobes and limbic system.

Brain tumors in surgical neuropathology of intractable epilepsies, with special reference to cerebral dysplasias.

Surgical specimens from 30 patients (13 males and 17 females) with intractable epilepsy with brain tumors and allied lesions were histopathologically examined: 4 of nonneurogenic origin (1 angiolipoma with cortical dysplasia and 3 cavernous hemangiomas), 2 low-grade fibrillary astrocytomas, 1 pleomorphic xanthoastrocytoma, 3 pilocytic astrocytomas with nuclear polymorphism, 1 oligoastrocytoma, 9 gangliogliomas, 3 gangliogliomatous lesions combined with tuberous sclerosis-like dysplastic changes, and 7 undetermined lesions suspected of being mixed glioma, dysembryoplastic neuroectodermal tumor (DNT), or dysplasia. They were all located supratentorially: in the temporal lobe in 21, frontal lobe in 6, and parietooccipital lobe in 3. The age of onset was under 20 years in most patients. Some kinds of dysplasias, such as focal cortical dysplasia, glioneuronal heterotopia, and clustered neurons in the hippocampus and amygdaloid nucleus, were combined in 11 cases, especially those with age of onset under 10 years. Pilocytic astrocytoma-like features were seen in 5 of the gangliogliomas and 3 of the undetermined lesions, and DNT-like features in 2 of the former and 3 of the latter. Gangliogliomas, pilocytic astrocytomas, mixed gliomas, DNTs, and dysplasias may be closely inter-related in the development of intractable epilepsies of young patients.