The combined application of the contrast-to-noise index and 80 kVp for cardiac CTA scanning before atrial fibrillation ablation reduces radiation dose exposure.

INTRODUCTION: To compare the radiation dose, diagnostic accuracy, and the resultant ablation procedures using 80 and 120-kVp cardiac computed tomography angiography (CCTA) protocols with the same contrast-to-noise ratio in patients scheduled for atrial fibrillation (AF) ablation. METHODS: This retrospective study was performed following institutional review board approval. We divided 140 consecutive patients who had undergone CCTA using a 64-MDCT scanner into two equal groups. Standard deviation (SD) of the CT number was set at 25 Hounsfield units (HU) for the 120-kVp protocol. To facilitate a reduction in radiation dose it was set at 40 HU for the 80 kVp protocol. We compared the two protocols with respect to the radiation dose, the diagnostic accuracy for detecting left atrial appendage (LAA) thrombi, matching for surface registration, and the resultant ablation procedures. RESULTS: At 120 kVp, the dose length product (DLP) was 2.2 times that at 80 kVp (1269.0 vs 559.0 mGy cm, p < 0.01). The diagnostic accuracy for thrombus detection was 100% using both protocols. There was no difference between the two protocols with respect to matching for surface registration. The protocols did not differ with respect to the subsequent time required for the ablation procedures and the ablation fluoroscopy time, and the radiation dose (p = 0.54, 0.33, and 0.32, respectively). CONCLUSION: For the same CNR, the DLP at 80 kVp (559.0 mGy cm) was 56% of that delivered at 120 kVp (1269.0 mGy cm). There was no reduction in diagnostic accuracy. IMPLICATIONS FOR PRACTICE: Maintaining CNR allows for a reduction in the radiation dose without reducing the image quality.

Tolerance to Stretching in Thiol-Terminated Single-Molecule Junctions Characterized by Surface-Enhanced Raman Scattering.

We investigated the change in the metal-molecule interaction in a 1,4-benzenedithiol (BDT) single-molecule junction using a combination of surface-enhanced Raman scattering spectra and current-voltage curves. During the stretching process, the conductance of the junction systematically decreased, accompanied by an increase in the vibrational energy of the CC stretching mode. By analyzing the current-voltage curves and Raman spectra, we found that the interaction between the π orbital of BDT and the electronic states of Au was diminished by the orientation change of BDT during the stretching process. A comparison with a 4,4'-bipyridine single-molecule junction revealed that the reduction of coupling of the Au-S contacts was smaller than that of Au-pyridine contacts. Therefore, the electronic states originating from the contact geometry are responsible for the tolerance to the stretching of thiol-terminated molecular junctions.

Investigation of Ag and Cu Filament Formation Inside the Metal Sulfide Layer of an Atomic Switch Based on Point-Contact Spectroscopy.

The atomic switches have attracted wide attention owing to their applications in nonvolatile electric devices. The atomic switch is operated by the formation and dissipation of a metallic filament inside a metal sulfide film, which is controlled by a solid electrochemical reaction. Although the metallic filament is considered to consist of metal atoms, the chemical species of the metallic filament are difficult to be identified due to challenges in observing the metallic filament inside the solid. In this study, we report the investigation on the metallic filament in the atomic switch with metal sulfide based on point-contact spectroscopy (PCS). By cooling the atomic switch, the switch voltage increased to 1 V, which allowed for the PCS measurement. The PCS revealed that the metallic filament was composed of Ag atoms in the case of the Pt/Ag2S/Ag atomic switch. We applied this technique to the Pt/Cu2S/Ag and Pt/Ag2S/Cu atomic switches to uncover the formation process of the metallic filament. In both atomic switches, the chemical species of the metallic filament were Ag. The metal atoms were supplied from both the metal electrode and the sulfide layer.

Stretch dependent electronic structure and vibrational energy of the bipyridine single molecule junction.

We have studied the stretch dependence of the electronic structure and vibrational energy for the 4,4'-bipyridine (BPY) single molecule junction, which was fabricated by the mechanically controllable break junction (MCBJ) using the highly stable nano MCBJ electrodes. The electronic structure and vibrational energy of the single molecule junction were studied by the current-voltage (I-V) curve and surface enhanced Raman scattering (SERS), respectively. The simultaneous SERS and I-V curve measurements revealed the lowest unoccupied molecular orbital (LUMO) and vibrational energy of the C-C stretching mode decreased with an increase in the metal-molecule distance. The molecular orbital energy shift and vibrational energy shift can be explained by the change in the degree of the hybridization of molecular and metal orbitals.

Investigation on the formation process of metal atomic filament for metal sulfide atomic switches by electrical measurement.

We have studied the formation process of the metal atomic filament for metal sulfide atomic switches by electrical measurement. The switching between ON and OFF states of the atomic switch is controlled by the application of the bias voltage for the atomic switches. The SET (OFF â†’ ON) and RESET (ON â†’ OFF) voltages were investigated for the atomic switch where the Ag2S or Cu2S layer were sandwiched between the Pt and Ag or Cu electrodes. The SET and RESET voltages of the Ag/Cu2S/Pt and Cu/Ag2S/Pt were close to those of the Ag/Ag2S/Pt atomic switch, and different from those of the Cu/Cu2S/Pt atomic switch. These results indicated that the dominant chemical species of the making and breaking part of the metal filament was Ag, and that the source of the metal filament was both the sulfide layer and the metal electrode.

Impact of junction formation processes on single molecular conductance.

We have investigated the electric conductance and atomic structure of single molecular junctions of pyrazine (Py), 4,4'-bipyridine (BiPy), fullerene (C60), and 1,4-diaminobutane (DAB). The single molecular junctions were fabricated by breaking Au contacts between an Au tip and the Au electrode surface in the presence of the target molecules (breaking process) or approaching the Au tip to the Au electrode surface covered by the molecules (making process). In the making process, no major conductance state was observed in the conductance histogram for DAB, while single conductance states were observed for the π-conjugated molecules of Py (10 mG0, G0∼ 77.45 µΩ-1), BiPy (3 mG0), and C60 (5 mG0). In contrast to the making process, two major conductance states were observed for Py (1 mG0 and 0.3 mG0), BiPy (0.6 mG0 and 0.2 mG0), and C60 (30 mG0 and 3 mG0) in the breaking process. The observed conductance behavior could be explained by the characters of the anchoring unit of molecules. In the making process, anchoring of molecules cannot be established by the point contact between the Au electrode and the localized lone pair of the N atom of DAB, Py, and BiPY, while molecules anchor on the Au electrode by using the plane-like contact between the Au electrode and the delocalized π electrons in the aromatic ring of Py, BiPY, and C60, which explains the difference in the observed conductance behavior between DAB and the π conjugated molecules of Py, BiPY, and C60 in the making process. In the breaking process, the delocalized π-electrons of Py, BiPY, and C60 can make a contact with the Au electrode surface and the lone pair on the N atom of DAB as well as Py and BiPY can bind to Au atoms, and therefore, single molecular junctions were formed for all systems. The present results indicate that the π-plane is important for making metal-molecule contacts and for the formation of the single molecular junction in the making process.

Chemically induced topological zero mode at graphene armchair edges.

The electronic and magnetic properties of chemically modified graphene armchair edges are studied using a combination of tight-binding calculations, first-principles modelling, and low temperature scanning tunneling microscopy (STM) experiments. The atomically resolved STM images of the hydrogen etched graphitic edges suggest the presence of localized states at the Fermi level for certain armchair edges. We demonstrate theoretically that the topological zero-energy edge mode may emerge at armchair boundaries with asymmetrical chemical termination of the two outermost atoms in the unit cell. We particularly focus our attention on armchair edges terminated by various combinations of the hydrogen (H, H2) and methylene (CH2) groups. The inclusion of the spin component in our calculations reveals the appearance of π-electron-based magnetism at the armchair edges under consideration.

Note: wearable near-infrared spectroscopy imager for haired region.

A wearable optical topography system was developed that is based on near-infrared spectroscopy (NIRS) for observing brain activity noninvasively including in regions covered by hair. An avalanche photo diode, high voltage dc-dc converter, and preamplifier were placed in an electrically shielded case to be safely mounted on the head. Rubber teeth and a glass rod were prepared to clear away hair and reach the scalp. These devices realized for the first time a wearable NIRS imager for any region of the cortex. The activity in the motor cortex during finger tapping was successfully observed.

Highly conductive molecular junctions based on direct binding of benzene to platinum electrodes.

Highly conductive molecular junctions were formed by direct binding of benzene molecules between two Pt electrodes. Measurements of conductance, isotopic shift in inelastic spectroscopy, and shot noise compared with calculations provide indications for a stable molecular junction where the benzene molecule is preserved intact and bonded to the Pt leads via carbon atoms. The junction has a conductance comparable to that for metallic atomic junctions (around 0.1-1G0), where the conductance and the number of transmission channels are controlled by the molecule's orientation at different interelectrode distances.

Evidence for a single hydrogen molecule connected by an atomic chain.

Stable, single-molecule conducting-bridge configurations are typically identified from peak structures in a conductance histogram. In previous work on Pt with H2 at cryogenic temperatures it has been shown that a peak near 1G0 identifies a single-molecule Pt-H2-Pt bridge. The histogram shows an additional structure with lower conductance that has not been identified. Here, we show that it is likely due to a hydrogen decorated Pt chain in contact with the H2 molecular bridge.

The effect of bonding of a CO molecule on the conductance of atomic metal wires.

We have measured the effect of bonding of a CO molecule on the conductance of Au, Cu, Pt and Ni atomic contacts at 4.2 K. When CO gas is admitted to the metal nanocontacts, a conductance feature appears in the conductance histogram near 0.5 of the quantum unit of conductance, for all metals. For Au, the intensity of this fractional conductance feature can be tuned with the bias voltage, and it disappears at high bias voltage (above approximately 200 mV). The bonding of CO to Au appears to be weakest, and associated with the formation of monatomic Au wire.

Effects of NMDA and MK-801 injected into the substantia nigra pars reticulata on jaw movements evoked by dopamine D1-/D2 receptor stimulation in the ventrolateral striatum: studies in freely moving rats.

The effects of NMDA and MK-801 injected into the substantia nigra pars reticulata on jaw movements evoked by dopamine D1/D2 receptor stimulation in the ventrolateral striatum were examined in freely moving rats, by using a magnet-sensing system combined with intracerebral drug microinjection technique. Bilateral injections of a mixture of SKF 82958 (5 microg) and quinpirole (10 microg), agonist at dopamine D1 and D2 receptors respectively, into the ventrolateral striatum elicited repetitive jaw movements. Bilateral injections of NMDA (0.01 and 0.05 microg/0.2 microl in each side) into the substantia nigra pars reticulata, which alone did not produce jaw movements, reduced the repetitive jaw movements evoked by the dopamine D1/D2 receptor agonist mixture in a dose-dependent manner. Injection of the non-competitive NMDA receptor antagonist, MK-801 (0.1 and 0.5 microg/0.2 microl in each side), into the substantia nigra pars reticulata, which alone did not produce jaw movements, prevented the dopaminergic jaw movements in a dose-dependent manner. Moreover, other behaviors such as grooming, rearing, yawning, vacuous chewing, and locomotor activity that occurred after injections of the dopamine receptor agonist mixture were not significantly altered by the bilateral injections of NMDA or MK-801 into the substantia nigra pars reticulata. Given our previous results showing that both agonist and antagonist of GABA(A) receptors injected into the substantia nigra pars reticulata inhibit the jaw movements elicited by dopamine D1/D2 receptor stimulation in the ventrolateral striatum, the present results suggest that there are complex functional interactions between NMDA and GABA(A) receptors within the substantia nigra pars reticulata that may be responsible for the common profiles in the effects of NMDA and GABA(A) receptor agents.

Self-consistent boundary condition for photon diffusion calculation.

The photon diffusion equation has been widely used to assess near-infrared spectroscopy of biological tissues. Here, we introduce the self-consistent boundary condition for the truncated boundary into this calculation. This reduces the effect of the boundary on the results, showing that the self-consistent boundary condition is useful for calculations for analyzing optical topographic images.

Dependence on the sample width of signals from a near-field optical microscope.

We numerically investigated signals from a scanning near-field optical microscope (NOM) for samples of various sizes by using the finite-difference time-domain method. Under the usual conditions that apply to detection, the signal intensity depends on the width of the sample, even though the sample will be wider than the wavelength, which is much larger than the aperture, i.e., the lateral resolution of the NOM. This is an obstacle to measuring the local optical constant of samples by means of obtaining the signal intensity. When waves propagating in all directions are collected, this dependence on the sample width is reduced. The whole angle detection is important for observing the distribution of the optical constants.

Rat two-generation reproductive toxicity study of bisphenol A.

This study was conducted to determine the low-dose effects of bisphenol A (BPA) in a rat two-generation reproduction study. Groups of 25 male and 25 female Crj: CD (SD) IGS rats were given BPA at 0.2, 2, 20, or 200 microg/kg/day by gastric intubation throughout the study beginning at the onset of a 10- and 2-week premating period, in F0 males and females, respectively, and continuing through the mating, gestation, and lactation periods, for two generations. There were adult (F0, F1, F2) and postnatal day (PND) 22 (F1, F2) necropsies: the oldest F2 males and females being killed at postnatal weeks 7 and 14, respectively. No compound-related clinical signs or effects on body weight or food consumption were observed in any generation. There were no compound-related changes in surface righting reflex, negative geotaxis reflex, mid-air righting reflex, pinna detachment, incisor eruption, eye opening, testes descent, preputial separation, or vaginal opening in F1 and F2 generations, or behavior in the open field or water filled multiple T-maze in the F1 generation. No test compound-related changes in estrous cyclicity, copulation index, fertility index, number of implantations, gestation length, litter size, pup weight, pup sex ratio, pup viability, or other functional reproductive measures were noted in any generation. A few significant changes in the anogenital distance (AGD) per cube root of body weight ratio were found at 0.2 and 20 microg/kg in F1 males, at 2, 20, and 200 microg/kg in F1 females, and at 20 and 200 microg/kg in F2 females. However, the changes in the AGD were consistently small (within 5% of control values), and no continuous changes in the AGD or AGD/cube root of body weight ratio were detected. There were no compound-related changes in epididymal sperm counts or motility in F0 and F1 males. No compound-related necropsy findings or effects on organ weight including the reproductive organs were found in any generation. Histopathologic examinations revealed no evidence of compound-related changes in any organs including the reproductive organs of both sexes. The data indicate that oral doses of BPA of between 0.2 and 200 microg/kg over 2 generations did not cause significant compound-related changes in reproductive or developmental parameters in rats.

Fabrication and observation of a standard sample for near-field optical microscopy.

We fabricated a standard sample for a near-field optical microscope using scanning probe lithography. The sample contains a wedged pattern, which allows the measurement of various sizes within one image. The optical resolution of our near-field optical microscope has been evaluated as 40 nm, which was obtained by measuring the narrowest separable gap width of the wedged pattern. Thus a standard sample containing the wedged pattern enables clear evaluation of the resolution.

Calculation of error propagation by use of total reflection geometry for evaluating third-order nonlinear optical materials.

The intrinsic error propagation in a technique that uses total reflection geometry for the measurement of chi(3) is calculated. The results show how accurately the parameters should be measured to obtain the chi(3) value with the required precision. The film thickness should be slightly less than the fundamental wavelength to reduce the chi(3) error that propagates from other parameters.

Second-order nonlinear optical susceptibility measurement of crystal with a glass prism in total-reflection geometry.

Second-harmonic generation in a uniaxial crystal in total-reflection geometry is precisely measured. A Y-cut plate and a Z-cut plate of quartz crystals were used as samples. The incident wave is totally reflected by a glass prism in contact with the sample crystal, and an evanescent wave penetrates into the sample as a fundamental wave. The results gave the quantitative values of the components for a nonlinear optical susceptibility tensor with various polarizations and with Y-cut and Z-cut quartz plates. This technique can be applied to various samples to evaluate their nonlinear optical efficiencies.

[Studies on screening for hard-of-hearing children by questionnaire. 2. Comparison of response rates to individual questions in 1-year-6-month-old children with normal hearing and hearing loss using a health screening questionnaire].

We report the results of studies on responses to questions on hearing impairment, comparing 165 school children whose hearing was diagnosed as normal at the time of admission to primary school and 37 children with hearing loss attending facilities for children with this disability. These children had been covered by similar surveys as part of the health screening for 1-year-6-month-old infants conducted by municipal authorities. Significant differences between the two groups were noted in the response rates to all questions on hearing. Similar differences were noted in the responses to questions on family history of hearing impairment. There were no significant differences in the incidences of asphyxia and jaundice at birth. The most striking differences were noted in the response rates to questions 6, 7, 8, 10, 11, 16, and 18. Most useful and universally valid in this survey were questions 8, 10 and 18 in addition to the question on whether or not parents suspected infantile hearing loss.