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This study explored long-term retention of spatial memory in rats using an eight-arm radial maze. Crystal and Babb (Learning and motivation, 39(4), 278-284, 2008) previously demonstrated that rats could retain spatial memory for up to 25 h in the radial maze. Notably, they found performance improved with 48-h intertrial intervals compared with 24-h intervals. Our study investigated the effects of extending intertrial intervals on long-term retention of spatial memory by reducing the potential for proactive interference. Each trial comprised a learning phase, during which subjects were required to sequentially visit four randomly selected arms, followed by a free-choice test that included all eight arms, conducted after increasing the retention and intertrial intervals. The retention intervals were systematically increased from 1 h to 24, 48, and, ultimately, 72 h, with corresponding intertrial intervals expanding from 24 to 48, 120, and 144 h. Performance significantly surpassed chance levels across all conditions, demonstrating that rats are capable of retaining spatial memory for up to 72 h., Competing Interests: Declarations. Conflict of interest: The authors declare no conflicts of interest. Ethics approval: Animal care and experimentation procedures were carried out in compliance with the Kanazawa University Animal Experimentation Regulations, under the approval number AP-214226. Consent to participate: Not applicable. Consent for publication: All authors reviewed the final version of the manuscript and consent to its publication., (© 2024. The Author(s).)

SPring-8-II is a major upgrade project of SPring-8 that was inaugurated in October 1997 as a third-generation synchrotron radiation light source. This upgrade project aims to achieve three goals simultaneously: achievement of excellent light source performance, refurbishment of aged systems, and significant reduction in power consumption for the entire facility. A small emittance of 50 pm rad will be achieved by (1) replacing the existing double-bend lattice structure with a five-bend achromat one, (2) lowering the stored beam energy from 8 to 6 GeV, (3) increasing the horizontal damping partition number from 1 to 1.3, and (4) enhancing horizontal radiation damping by installing damping wigglers in long straight sections. The use of short-period in-vacuum undulators allows ultrabrilliant X-rays to be provided while keeping a high-energy spectral range even at the reduced electron-beam energy of 6 GeV. To reduce power consumption, the dedicated, aged injector system has been shut down and the high-performance linear accelerator of SACLA, a compact X-ray free-electron laser (XFEL) facility, is used as the injector of the ring in a time-shared manner. This allows the simultaneous operation of XFEL experiments at SACLA and full/top-up injection of the electron beam into the ring. This paper overviews the concept of the SPring-8-II project, the system design of the light source and the details of the accelerator component design., (open access.)

Information-seeking behavior often features in research on metacognition in non-human animals; some species seek more information when they do not know the location of a food reward. Rats are known to do this in situations of uncertainty, but it is still unclear if they seek information prospectively for solving a later problem. In this study, we investigated rats' information-seeking responses in two areas that presented different cognitive challenges ( N  = 4). In one area, a memory task was presented in which rats could access a cue for a food reward during the information-seeking phase of a trial, but the cue was removed before the subsequent test phase. In the other area, a discrimination task presented a cue that was available in both the information-seeking and the test phases, so that it was not necessary to seek information prospectively. The memory and discrimination test trials were given in quasi-random order (Experiment 1). Rats explored in the memory task area no more than in the discrimination task area during the information-seeking phase, even after extensive training. When they were exposed exclusively to the memory task over multiple sessions (Experiment 2), they developed a strategy of exploring the available object cues. In Experiment 3, rats were found to stay longer in an area, which had an object than in other, less potentially informative areas; they were sensitive to the presence of information. Although these results did not support the existence of prospective information-seeking in rats, they do not necessarily imply that rats lack related abilities. This consideration is due to the constraints of the small sample size and the limited scope of the testing environment. Accumulating not only positive but also negative evidence would further understanding of the factors influencing metacognitive responses in non-human animals., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Iwasaki and Taniuchi.)

In high-frequency pulsed magnets, such as kickers in particle accelerators, it is essential to reduce eddy currents that could be induced in the magnet core during excitation not to distort and attenuate the magnetic field pulse. A novel iron lamination scheme with additional interlaminar insulation is proposed for the magnet core of such pulsed magnets. A laminated steel sheet core is formed by alternately stacking thin steel and insulation sheets. For application to matched kicker magnets for accelerators, test magnets with the new and conventional iron lamination were designed, assembled, and extensively evaluated. The pulsed magnetic field waveforms of two test magnets with the new lamination successfully matched to below 0.1% over the entire pulse duration, which was significantly better than those with the conventional lamination. Among the applications of the developed high-frequency pulsed magnets, beam injection kickers for the coming next generation light sources and future colliders, where suppression of the transient stored-beam oscillation during beam injection is crucial, are considered to be promising.

Nematicity is ubiquitous in the electronic phases of iron-based superconductors. The order parameter that characterizes the nematic phase has been investigated in momentum space, but its real-space arrangement remains largely unexplored. We use linear dichroism (LD) in a low-temperature laser–photoemission electron microscope to map out the nematic order parameter of nonmagentic FeSe and antiferromagnetic BaFe 2 (As 0.87 P 0.13 ) 2 . In contrast to structural domains, which have atomic-scale domain walls, the LD patterns in both materials show peculiar sinusoidal waves of electronic nematicity with wavelengths more than 1000 times as long as the unit cell. Our findings put strong constraints on the theoretical investigation of electronic nematicity.

The long-chain acyl-CoA synthetases (LACSs) are involved in lipid synthesis, fatty acid catabolism, and the transport of fatty acids between subcellular compartments. These enzymes catalyze the critical reaction of fatty acyl chains to fatty acyl-CoAs for the triacylglycerol biosynthesis used as carbon and energy reserves. In Arabidopsis , LACSs are encoded by a family of nine genes, with LACS9 being the only member located in the chloroplast envelope membrane. However, the comprehensive role of LACS9 and its contribution to plant metabolism have not been explored thoroughly. In this study, we report on the identification and characterization of LACS9 mutants in rice plants. Our results indicate that the loss-of-function mutations in OsLACS9 affect the architecture of internodes resulting in dwarf plants with large starch granules in the chloroplast, showing the suppression of starch degradation. Moreover, the plastid localization of α-amylase I-1 (AmyI-1)-a key enzyme involved in starch breakdown in plastids-was suppressed in the lacs9 mutant line. Immunological and confocal laser scanning microscopy analyses showed that OsLACS9-GFP is located in the chloroplast envelope in green tissue. Microscopic analysis showed that OsLACS9s interact with each other in the plastid envelope membrane. Furthermore, OsLACS9 is also one of the proteins transported to plastids without a transit peptide or involvement of the Toc/Tic complex system. To identify the plastid-targeting signal of OsLACS9, the transient expression and localization of a series of N-terminal truncated OsLACS9-green fluorescent protein (GFP) fusion proteins were examined. Truncation analyses identified the N-terminal 30 amino acid residues to be required for OsLACS9 plastid localization. Overall, the data in this study provide an advanced understanding of the function of OsLACS9 and its role in starch degradation and plant growth.

Directed forgetting in rats, to elucidate active control of memory rehearsal processes while controlling for nonmemorial artifacts, was examined using an eight-arm radial maze. To-be-remembered and to-be-forgotten items were presented at different arms in the same trial. A trial consisted of learning and test phases. Rats needed to remember win or loss of a food pellet presented in the middle of the arms, signaling presence or absence of a large reward there in the subsequent test phase. Two other qualitatively different foods placed at the end of the arms served as remember (R) or forget (F) cues, signaling whether those arms would be presented in the test phase. Compared with the normal test, rats' performance deteriorated significantly if the arms previously marked by F-cues in the preceding learning phase were actually used in the test phase, showing reliable directed forgetting in rats. Rats were also tested in a condition in which F-cues were not presented at all, and thus rats had to remember all the arms. Although positive evidence of reduction of memory load in working memory by utilizing F-cues was not demonstrated, analysis of individual data suggested that utilization of R-cues and F-cues interfered with the main task of remembering win/lose information.

This study examined the effectiveness in rats of 'returning to home cage' as a reward for learning a Lashley III maze. Rats could return to their home cage directly (Direct HC group) or they could be removed manually by an experimenter from the maze's goal box (Indirect HC group). In the third group, hungry rats received a food reward in the goal box (Food group). The Direct HC group reliably learned the maze and its performance was very similar to that of the Food group. In contrast, performance by the Indirect HC group was significantly poorer than the Direct HC group, as well as the Food group, possibly due to the negative impact of handling during removal from the goal box. These results suggest that a 'home cage reward' is as effective a procedure for rats in maze learning as previously reported in mice (Blizard et al., 2003, 2006)., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The melting curve of MgO is extended up to 4 TPa, corresponding to the Jovian core pressure, based on the one-step thermodynamic integration method implemented on ab initio molecular dynamics. The calculated melting temperatures are 3100 and 16 000 K at 0 and 500 GPa, respectively, which are consistent with previous experimental results, and 20 600 K at 3900 GPa, which is inconsistent with a recent experimental extrapolation, which implies the molten Jovian core. A quite small Clapeyron slope ([Formula: see text]) of [Formula: see text] is found at 3900 GPa due to comparable densities of the liquid and B2 phases under extreme compression. The Mg-O coordination number in the liquid phase is saturated at around 7.5 above 1 TPa and remains smaller than that in the B2 phase (8) even at 4 TPa, suggesting no density crossover between liquid and crystal and thus no further denser crystalline phases. Dynamical properties (atomic diffusivity and viscosity) are also investigated along the melting curve to understand these behaviors in greater detail.

This experimental series examines rats' concurrent learning of multiple oddity discrimination and its transfer to novel stimuli. Three rats were trained to discriminate an odd object from five identical objects in a row. After acquisition of the AAAAAB problem, the BBBBBA set was added to training. At the start of concurrent training with both sets, performance on BBBBBA was significantly below chance, suggesting that rats had acquired a tendency to respond to and/or avoid specific features of objects during the initial AAAAAB training. Although all rats learned the two problems reliably, no transfer effect was observed during tests with novel sets CCCCCD and DDDDDC. After the first transfer test, rats performed reliably for stimulus sets AAAAAB, BBBBBA, CCCCCD, and DDDDDC concurrently. Although one rat showed reliable transfer for novel test problems EEEEEF and FFFFFE, the possibility of biased test performance between stimulus sets, by choosing one of two test objects, could not be excluded. However, following the transfer tests, all rats responded significantly to 20 novel problems immediately after they were introduced into training. These findings offer evidence of rats' capacity for concurrent oddity discrimination using multiple stimulus sets, as well as preliminary evidence of relational oddity learning in rats., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Two-dimensional electron gases at oxide surfaces or interfaces show exotic ordered states of matter, like superconductivity, magnetism or spin-polarized states, and are a promising platform for alternative oxide-based electronics. Here we directly image a dense population of randomly distributed ferromagnetic domains of ∼40 nm typical sizes at room temperature at the oxygen-deficient surface of SrTiO3, a non-magnetic transparent insulator in the bulk. We use laser-based photoemission electron microscopy, an experimental technique that gives selective spin detection of the surface carriers, even in bulk insulators, with a high spatial resolution of 2.6 nm. We furthermore find that the Curie temperature in this system is as high as 900 K. These findings open perspectives for applications in nano-domain magnetism and spintronics using oxide-based devices, for instance through the nano-engineering of oxygen vacancies at surfaces or interfaces of transition-metal oxides.

In this study, we examined rats' discrimination learning of the numerical ordering positions of objects. In Experiments 1 and 2, five out of seven rats successfully learned to respond to the third of six identical objects in a row and showed reliable transfer of this discrimination to novel stimuli after being trained with three different training stimuli. In Experiment 3, the three rats from Experiment 2 continued to be trained to respond to the third object in an object array, which included an odd object that needed to be excluded when identifying the target third object. All three rats acquired this selective-counting task of specific stimuli, and two rats showed reliable transfer of this selective-counting performance to test sets of novel stimuli. In Experiment 4, the three rats from Experiment 3 quickly learned to respond to the third stimulus in object rows consisting of either six identical or six different objects. These results offer strong evidence for abstract numerical discrimination learning in rats.

We report the thermally induced unconventional cracking of graphene to generate zigzag edges. This crystallography-selective cracking was observed for as-grown graphene films immediately following the cooling process subsequent to chemical vapor deposition (CVD) on Cu foil. Results from Raman spectroscopy show that the crack-derived edges have smoother zigzag edges than the chemically formed grain edges of CVD graphene. Using these cracks as nanogaps, we were also able to demonstrate the carrier tuning of graphene through the electric field effect. Statistical analysis of visual observations indicated that the crack formation results from uniaxial tension imparted by the Cu substrates together with the stress concentration at notches in the polycrystalline graphene films. On the basis of simulation results using a simplified thermal shrinkage model, we propose that the cooling-induced tension is derived from the transient lattice expansion of narrow Cu grains imparted by the thermal shrinkage of adjacent Cu grains.

We report the first experiments carried out on a new chemical and magnetic imaging system, which combines the high spatial resolution of a photoemission electron microscope (PEEM) with a continuous-wave deep-ultraviolet laser. Threshold photoemission is sensitive to the chemical and magnetic structures of the surface of materials. The spatial resolution of PEEM is limited by space charging when using pulsed photon sources as well as aberrations in the electron optics. We show that the use of a continuous-wave laser enabled us to overcome such a limit by suppressing the space-charge effect, allowing us to obtain a resolution of approximately 2.6 nm. With this system, we demonstrated the imaging of surface reconstruction domains on Si(001) by linear dichroism with normal incidence of the laser beam. We also succeeded in magnetic imaging of thin films with the use of magnetic circular dichroism near the Fermi level. The unique features of the ultraviolet laser will give us fast switching of the incident angles and polarizations of the photon source, which will be useful for the characterization of antiferromagnetic materials as well as ferromagnetic materials.

Properties of hypermobile water (HMW) were studied by Raman OH-stretching spectroscopy. Hydration water properties measured by Raman OH-stretching spectra of NaX/KX (X: Cl, Br, I) solutions (0.05-0.2 M) were comparatively analyzed with the data by dielectric relaxation spectroscopy (DRS), NMR, and statistical mechanical studies. The Raman OH-stretching spectra were well-fitted with linear combinations of the spectra of pure water both at the same and the higher temperatures. The fitting analysis determined the "structure temperature" Tstr and mole fraction of the high Tstr water region, giving the hydration number Nhyd, for each electrolyte solution. The determined Tstr was much higher than the solution temperature of 293 K for each tested salt and was higher for larger halide ions, consistent with commonly known "structure-breaking" order Cl < Br < I. No significant differences in Nhyd were observed between NaX and KX and among even halide ion species within the experimental errors. Measured Nhyd values of 25-27 were much greater than the reported numbers by NMR chemical shift and (17)O NMR relaxation studies and comparable to the numbers of hypermobile water reported in the previous DRS studies. The results indicated that the hydration region around NaX or KX measured by the present Raman study was nearly overlapped with the region of HMW by DRS. It was also suggested that differences in the ion size effects on Tstr and the DR frequency resulted from the sensitivity difference to long-range many-body interactions among water molecules. High structure-temperature regions were also detected by the analysis of OH-stretching and OD-stretching bands for 0.2 M NaI in H2O/D2O mixed solvent of 50 mol %, and we found that both OH-stretching and OD-stretching bands have almost equivalent Tstr ≈ 330 K and mole fractions with each other.

The organic haze of aerosols that shrouds the Saturnian moon Titan has previously been studied by both observations and laboratory simulation experiments. Here we report the abiotic formation of amino acid precursors in complex organic molecules during experimental simulation of the environment near Titan's surface with proton irradiation. Pyrolysis of the organic molecules formed in the simulated Titan atmosphere by proton irradiation at 600°C yielded compounds that contained HCN and NH₃ (m/z = 27 and 17). These experimental results are consistent with the molecular information obtained by pyrolysis gas chromatography/mass spectrometry (pyrolysis GC/MS) of samples collected by the Huygens probe to Titan. Scanning electron microscopy (SEM) and three-dimensional atomic force microscopy (AFM) images of the irradiation products reveal nanometer-scale filaments and globules in complex amorphous structures (approximately 1000 Da). Isotope probing experiments by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) show that oxygen atoms were incorporated into the racemic amino acids by hydrolysis of ¹⁸O-labeled water. We suggest that the amino acid precursors possibly formed after water hydrolysis, as suggested in a previous observational study (C. A. Griffith, T. Owen, T. R. Geballe, J. Rayner, and P. Rannou, Science, 2003, 300, 628). We propose that cosmic rays are a significant and effective energy source for producing complex organics and amino acid precursors in Titan's atmospheric haze.

Investigation of the non-equilibrium dynamics after an impulsive impact provides insights into couplings among various excitations. A two-temperature model (TTM) is often a starting point to understand the coupled dynamics of electrons and lattice vibrations: the optical pulse primarily raises the electronic temperature T(el) while leaving the lattice temperature T(l) low; subsequently the hot electrons heat up the lattice until T(el) = T(l) is reached. This temporal hierarchy owes to the assumption that the electron-electron scattering rate is much larger than the electron-phonon scattering rate. We report herein that the TTM scheme is seriously invalidated in semimetal graphite. Time-resolved photoemission spectroscopy (TrPES) of graphite reveals that fingerprints of coupled optical phonons (COPs) occur from the initial moments where T(el) is still not definable. Our study shows that ultrafast-and-efficient phonon generations occur beyond the TTM scheme, presumably associated to the long duration of the non-thermal electrons in graphite.

Calicotyle japonica n. sp., collected from the uterus, rectal gland, archinephric duct and cloaca of the shortspine spurdog Squalus mitsukurii Jordan & Snyder (Squaliformes) off the Pacific coast of Japan, is described. The new species can be distinguished from C. inermis Woolcock, 1936 by the shape of the male copulatory organ; in C. japonica this is directed anteriorly, is sharply bent in the middle and then increases in width toward the tip, whereas it is long, coiled and uniform in width throughout its entire length in C. inermis. Furthermore, the intestinal caeca have many irregular diverticula on both sides and the vaginal apertures are at the level of the common genital pore in C. japonica, whereas in C. inermis the intestine is smooth and the vaginae open at the level of the oötype. A phylogeny constructed using LSU rDNA data indicates that the new species is grouped with other Calicotyle species; based on this, Gymnocalicotyle Nybelin, 1941 is synonymised with Calicotyle Diesing, 1850. Calicotyle is divided into two major clades, with the new species being grouped with Calicotyle species infecting sharks and the second clade consisting of Calicotyle spp. infecting rays. This suggests that the loss of the hamuli in C. japonica and C. inermis, both parasites of sharks, is a comparatively recent event in the evolution of the genus.

Yeasts of the genus Lipomyces are known as fat yeasts, and they store large amounts of lipids. Because the major lipid produced by Lipomyces is triglyceride, which can be used as a food and energy resource, the control of lipid production by Lipomyces sp. is an important issue. Here we report the effects of UV irradiation on lipid production in Lipomyces lipofer cells. UV irradiation (315-400 nm) led to a 4-fold increase in the amount of triglyceride per cell. We discovered a novel phenomenon, that UV irradiation promotes triglyceride accumulation in L. lipofer.

We visualized flavonol distribution in the abaxial epidermis of onion scales without chemical processes via detection of blue-light-induced green autofluorescence. Our visualizing results indicated an unequal intercellular distribution of flavonols among epidermal cells causing a patch distribution in the epidermis, and indicated that flavonol accumulation in ultraviolet irradiated-onion scales was in uniformity with epidermal cells, probably to compensate for their stress-hypersensitiveness.

Descriptions are given for two new species of hexabothriid monogeneans, one collected from the gills of shortspine spurdog Squalus mitsukurii and the other from the gills of the ginzame Chimaera phantasma in Sagami Bay on the Pacific coast of Japan. Squalonchocotyle mitsukurii n. sp. from Squalus mitsukurii can be distinguished from Squalonchocotyle squali MacCallum, 1931, the most closely related species, by the inwardly curved vagina. Callorhynchocotyle sagamiensis n. sp. from Chimaera phantasma can be distinguished from all the known species of Callorhynchocotyle Suriano & Incorvaia, 1982 by the structure of the cirrus; in the new species, the cirrus is entirely muscular with a widened opening, while in the four known species it comprises a tubular proximal part and a bulbous distal part.

Top-up operation allows SPring-8 to provide highly stable X-ray beams with arbitrary filling patterns. The implementation of top-up operation is described, with a focus on the simultaneous achievement of stability of stored current, beam orbit, purity of an isolated single bunch, and beam injection efficiency. Stored-current fluctuations have been routinely reduced to a level of 10(-3). Stored-beam oscillation on frequent beam injection, which was originally regarded as the most serious problem, has been successfully suppressed to a sufficiently low level that it never perturbs imaging experiments. Current impurities in nominally empty buckets have been reduced to a level of 10(-9) over more than one week of operation, making possible the measurement of time-resolved spectra using high-current bunches. Finally, excellent injection efficiency, higher than 80%, is routinely obtained, even for small undulator gaps, which is critical for preventing radiation damage to insertion-device magnets and to reduce leakage radiation. The process of achieving highly stabilized top-up operation at SPring-8 and its utility for user experiments are described.

The present study examined rats' learning process of three-item series task in a modified Hill maze, using a subset test and a wild card test. In the first phase, four rats were trained with three item series composed of three simultaneously presented barriers (items A, B, C). They learned to get over the barriers in a prescribed order (A-B-C) reliably. In the next phase, three subsets of items (AB, BC, AC) were presented as prove trials. All rats responded to the subsets in a serial order consistent with the original series. In the final phase, rats were trained to produce "wild card" series (W-B-C, A-W-C, A-B-W) in addition to the original series. With training, rats mastered to substitute the wild card item (W) for the omitted original items. These results suggested that rats learned the series without using item association learning or response chaining.

The present paper evaluates the inclusion of a standard strain or outbred stock in multi-strain behavioral phenotyping protocols to perform the same role as the external standard in biochemical assay procedures. As potential standards, the F344 inbred strain and an outbred stock of Long Evans were tested with three other inbred strains. To evaluate the influence of rearing conditions on phenotype stability, one group of F344s was born at the University of Tsukuba, another, bred elsewhere and delivered to Tsukuba at 4 weeks of age. All animals were tested in open-field (OF), runway emergence (RE) and digging tests as adults. The results showed no influence of breeding or transportation history on OF and RE behavior of the two F344 groups, while there was evidence that digging behavior may be affected by the different rearing experience. The inclusion of a 'standard strain or stock' in phenotyping protocols involving multiple inbred strains or lines of rats, mice and flies has obvious advantages by providing a reference point for inter-laboratory comparisons. The properties of inbred strains and outbred stocks favorable to their use as standards are discussed.

The first known demonstration of tunable terahertz-wave generation by difference-frequency generation of dual signal-wave quasi-phase-matched optical parametric oscillation was performed with periodically poled LiNbO(3) (PPLN) with a series of gratings. An organic ionic salt, 4-dimethylamino-N-methyl-4-stilbazolium-tosylate (DAST), was used as a nonlinear crystal. A compact terahertz-wave source resulted, and changing the temperature of the PPLN permitted the wavelength to be varied from 120 to 160 microm. The wavelength could be tuned from 100 to 700 microm by proper selection of combinations of periodically poled gratings.

Using runway training procedure, three experiments examined effects of interrun interval (IRI) shift on serial pattern learning in rats. Series consisted of varying number of 0.045 g food pellets given in a goal box of a runway. Groups of rats were trained with 24-10-1-0 or 24-16-10-6-3-1-0 series (Experiment 1), 14-7-3-1-0 series (Experiment 2), and 18-12-6-3-1-0 or 18-7-7-7-1-0 series (Experiment 3), under either short (15-20 s) or long (5-15 min) IRI. In test phases, IRI was shifted from short to long or vice versa. Anticipation of 0 pellet was not disrupted by shortening of IRI, whereas lengthening of IRI eliminated the 0 pellet anticipation of the five- to seven-item monotonic series but did not eliminate that for the four-item series and the nonmonotonic series. These results suggest that rats learn a series with different strategies depending on IRI, pattern length, or structural complexity of a series.

We have demonstrated, for the first time to our knowledge, periodic poling of a 2-mm-thick near-stoichiometric LiTaO(3) substrate and its operation in a nanosecond optical parametric oscillator. Because the coercive field of stoichiometric LiTaO(3) is ~2 kV/mm , which is approximately one tenth that of the conventional congruent field, periodic poling of thicker stoichiometric substrates was successfully performed by means of an electric-field poling process at room temperature. The performance of a parametric oscillator with a 1-mm-thick sample was compared with that of the oscillator with the periodically poled congruent oscillator. The stoichiometric device exhibited better performance.

Among nonlinear materials, the organic ionic salt crystal 4-dimethylamino- N -methyl-4-stilbazolium-tosylate (DAST) is known for its large nonlinearity. We generated a coherent terahertz (THz) wave, using DAST, from the difference frequency between two oscillating wavelengths of an electronically tuned Ti:sapphire laser. In LiNbO(3), LiTaO(3), KTiOPO(4), and GaP crystals, THz-wave generation was not observed under the same experimental conditions. This result proves the high efficiency of DAST crystals for generation of difference-frequency THz waves.

Greater than 6-microm-oscillation was demonstrated by means of optical parametric oscillation with periodically poled LiNbO3 (PPLN). The interaction length and thickness were 40 mm and 500 microm. The pump source used was a Q-switched Nd:YAG laser with a pulse duration of 120 ns and a repetition rate of 1 kHz. The tuning ranges of the idler waves were 6.57-6.56, 6.22-6.12, and 6.06-5.94 microm for PPLN wafers of 20-, 21.3-, and 22-microm periods, respectively.

In recent years widely tunable terahertz- (THz-) wave generation from LiNbO(3) optical parametric oscillators (OPO's) has been successfully demonstrated by use of the prism output-coupler method. However, there remains a problem of large absorption loss for generated terahertz waves inside the crystal, so we investigated the cryogenic characteristics of the OPO. We achieved 125-times-higher THz-wave output and 32% reduction of the generation threshold by cooling the crystal to 78 K. This scheme also provides direct loss measurement at THz frequency, and we found that the THz-wave enhancement mechanism is improvement of the gain as well as the reduction of the absorption coefficient.

A new alignment method for Helmholtz coils is proposed. This method is based on a probe, whose axis is the same as the alignment axis. This probe includes one magnetic sensor, whose position is slightly shifted from the probe axis, and which is set perpendicular to the axis. Using this probe, the tilt and shift of the magnetic centre of Helmholtz coils can be aligned to within an order of 0.1 mrad and 0.1 mm, respectively. Moreover, by this method, effects of terrestrial magnetism and tilt of the magnetic sensor can be removed from the measurement. This alignment method is presented along with an estimate of the alignment accuracy of the SPring-8 linac injector.

Two experiments using rats as subjects examined effects of item-arrangement on acquisition and extinction in serial learning. In Experiment 1, Group A received series of 16-0-16 and 1-0-1 food pellets in a runway, while Group D received 1-0-16 and 16-0-1 series. Both groups manifested a remote anticipation of the third item on Run 2, and current anticipation of the third item on Run 3. In extinction phase, resistance was greater in Group D than Group A. These results indicate that the first item signaled not only the second item, but also the third item. In Experiment 2, two of the four groups were trained with either of the following monotonic series: 0-16-0-8-0-4- 0-2-0-1 (Group M16) or 0-1-0-2-0-4-0-8-0-16 (Group M1), while the other two groups were given one of the following nonmonotonic series: 0-16-0-2-0-4-0-8-0-1 (Group NM16) or 0-1-0-8-0-4-0-2-0-16 (Group NM1). In extinction phase, Group M16 showed the least resistance. These results are discussed mainly on the basis of remote association view and structural complexity theory of serial learning.

ZBP-89 is a Krüppel-type zinc finger protein that binds to the gastrin EGF response element (gERE). Sp1 binds to the same DNA element and transactivates gastrin promoter activity, whereas ZBP-89 competes for Sp1 binding and prevents EGF induction. Both transcription factors mediate growth factor signals originating from the EGF receptor and thus were studied in normal and neoplastic tissues or cell lines. When compared to normal tissue from the same patient, ZBP-89 protein expression was increased in neoplastic tissue from the stomach antrum and in malignant cell lines. RT-PCR analysis of ZBP-89 mRNA correlated with protein overexpression. Immunocytochemical studies confirmed that ZBP-89 expression is elevated in neoplastic tissue and chronic gastritis, whereas Sp1 expression was nearly unchanged. These results suggest that the transcription factor ZBP-89, like Sp1, may be a marker for neoplastic transformation in some gastric cancers.

Monitoring by means of blood and urine analysis for methanol was successfully applied in 32 male workers who were exposed to methyl methacrylate (MMA) monomer at 6 ppm as a geometric mean and at 112 ppm as the maximum. Measurement of time-weighted average (TWA) intensity of the vapor exposure was successfully conducted with a diffusive sampler with activated carbon cloth as an adsorbent. Methanol concentrations in whole blood, serum, and urine samples were measured by headspace gas chromatography. The methanol concentrations in the three biological samples collected at the end of 8-h workshifts related linearly with the TWA MMA vapor concentrations, with correlation coefficients of 0.8-0.9. Quantitative evaluation of MMA in vapor and of methanol in urine suggests that only 1.5% of MMA inhaled will be excreted in urine as methanol. There were no significant clinical symptoms or abnormal hematological or serum biochemical findings at this exposure level, except that some workers complained throat irritation and frequent cough and sputa. The results indicate that biological monitoring by analysis for methanol is sensitive enough to detect MMA exposure at levels at which no serious health effects are to be expected.

We report the characterization of a quasi-phase-matched second-harmonic generation device in LiTaO(3) that has a periodically domain-inverted region and a proton-exchanged channel waveguide. A blue-light power of 2.4 mW was obtained at a 424-nm wavelength. The observed temperature bandwidth for FWHM power is approximately 3 degrees C-cm, which is three times wider than that in a similar device in LiNbO(3). It is also shown that diffraction-limited focusing of the generated blue light may be obtained.