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To investigate the luminescence characteristics after exposure to X-ray radiation, we developed an independent, small X-ray irradiation system comprising a Varian VF-50J mini X-ray generator, a Pb collimator, a delay shutter, and an Al absorber. With this system, the apparent dose rate increased linearly to 0.8 Gy/s against the emission current for a 50 kV anode potential when the shutter was delayed for an initial 4 s and the Al absorber was 300 µm thick. In addition, an approximately 20 mm diameter sample area was irradiated homogeneously with X rays. Based on three-dimensional (3D) thermoluminescence (TL) spectra, the small X-ray irradiator was considered comparable to the conventional 90Sr/90Y beta source even though the TL intensity from beta irradiation was higher than that from X-ray irradiation. The single aliquot regenerative (SAR) growth curve for the small X-ray irradiator was identical to that for the beta source. Therefore, we concluded that the characteristics of the small X-ray irradiator and the conventional 90Sr/90Y beta source were similar and that X ray irradiation had the potential for being suitable for use in luminescence dosimetry.

Fading test using the single aliquot additive dose method with pulsed optically stimulated luminescence (SAAD-POSL method) was applied to core–disc samples extracted from heated red brick, tile, roof-tile, and toilet porcelain after X-ray and beta irradiation. From thermoluminescence measurements of each material, the optimal preheat condition of the SAAD-POSL method was first determined as 170 °C for 10 s. Fading characteristics of core–disc samples of heated red brick obtained using the SAAD-POSL method were similar to those of quartz grains (90–250 μm) obtained using the SAR-OSL method, regardless of the differences in the sample and radiation type. Fading evaluations of the core–disc samples of these building materials two weeks after irradiation showed that the equivalent dose (ED) decreased between 5% and 42%. The results indicate that the fading characteristics will be able to contribute to a more accurate estimation of the ED value using the SAAD-POSL method.

Investigations of bleaching and thermoluminescence (TL) response to radiation dose of quartz are importance in luminescence dating. Although such research has been extensively carried out for various types of quartz, most work was performed on the basis of TL intensity integrated for a particular temperature range on the glow curve, without any peak separation. In this study we investigated bleaching by a blue light stimulation and radiation dose behaviour for separated TL glow peaks of quartz, which are thermally stable, by using the computerized glow curve deconvolution (CGCD) method combined with the Tm–Tstop method. The Tm–Tstop method indicates that the glow curve of quartz is the superposition of at least seven components (P1–P7) in the temperature range between room temperature and 450 °C. A bleaching experiment for four thermally stable glow peaks (P4–P7) using a blue light stimulation revealed that the bleaching rate of peak P4 exhibits three different exponential decays, whereas the peaks P5, P6 and P7 are bleached with two different exponential decays. After bleaching of 12 h, the TL intensity of peaks P4, P5, P6 and P7 were reduced to approximately 6%, 16%, 26% and 68% of the initial value, respectively. Additionally, in a study of the radiation dose response of the four thermally stable glow peaks, all peaks have a similar pattern, which are well fitted by a single saturating exponential function.

To establish a fast assessment method of accidental dose, core disc samples were extracted from a heated red brick, roof tile, ceramic tile, and toilet porcelain, which are commonly used building materials. We examined the physical characteristics of pulsed optically stimulated luminescence (POSL) signals from these samples, and tested the reliability of the single aliquot additive dose (SAAD)-POSL method over a range of 7 Gy. In addition, when the SAAD-POSL method was applied, the minimum detectable dose (MDD) was as low as 0.01 Gy for the heated red brick, and the calculation time for an equivalent dose was as short as 2 h. This result indicates that the SAAD-POSL method is more effective as a fast assessment method of accidental dose than the SAR-OSL method.

Calcite has been of particular interest in studies of thermoluminescence (TL) because of its geological and archeological importance. Although extensive research on the TL glow curves of calcite has been conducted, most previous works have been based on the TL intensity integrated over a particular temperature range on the glow curve, without any separation of peaks. In this paper, the physical characteristics of the overlapping peaks in the TL glow curves of a calcite sample are investigated. These properties can provide useful information for determining the radiation dose absorbed to the sample in radiation dosimetry and luminescence dating research. The Tm–Tstop method is employed to identify the number of hidden glow peaks, and the kinetic parameters of each separated glow peak, including the thermal activation energy, kinetic order, and frequency factor, are evaluated using a computerized glow curve deconvolution (CGCD) method. The Tm–Tstop method indicates that the glow curve of calcite is the superposition of at least four components (P1 – P4) in the temperature range between room temperature and 450 °C. A bleaching experiment for two separated glow peaks (P3 and P4) using a solar simulator revealed that the bleaching rates of peak P3 show two exponential decays, and after bleaching, the TL intensity of peak P3 is reduced to approximately 4% of the initial value. In contrast, peak P4 is bleached exponentially to approximately 30% of the initial TL intensity and thereafter shows no detectable change in intensity. In addition, in a study of the radiation dose response of the two peaks, both peaks have a similar pattern, exhibiting a linear increment up to the maximum dose investigated, 520 Gy.

The Korean Peninsula is located in the intraplate regime of the Eurasian plate, and numerous historical and instrumental earthquakes have been recorded. Among these, the largest earthquakes were recorded in and around the Gyeongju and Ulsan areas in the southeastern part of the Korean Peninsula. We recently reexamined faults in Jinhyun and Jintee, part of the Ulsan fault swarm, to clarify the average slip rate and the maximum potential magnitude of future earthquakes. The Jinhyun fault extends to the Tabgol fault (J-T fault), and the Jintee fault extends to the Singye (S-J fault). The faults cut through alluvial fans and are covered by unconsolidated granite washes on Tertiary granite. All of these faults show reverse sense of motion such that the Tertiary granite has been moved upward with a high angle relative to the Quaternary sediments. Most sediment samples from the Jinhyun and Jintee faults showed quartz OSL ages of ca. 40–60 ka. The calculated vertical slip rate for the Jinhyun and Jintee faults is in the range of 0.18–0.28 mm/y. Based on maximum earthquake magnitudes calculated from geological survey results as well as historical and instrumental earthquake information, the maximum potential magnitudes of future earthquakes in the Gyeongju area are estimated to range from 4.6 to 5.6. This suggests that the potential maximum magnitude in the southern Korean Peninsula is presumably not more than 6.

In recent years, considerable developments in optically stimulated luminescence (OSL) have been made in the fields of radiation dosimetry, age determination, and medical applications. A compact and economical OSL system comprising a precision x-y-z stage for loading 12 samples, a small X-ray generator for radiation dosing, and two powerful blue light emitting diodes (LEDs) for optical stimulation equipped with VIS liquid light guides (VIS-LLGs) has been developed. This paper describes the principal features of the system along with the examples of measurements performed by the system.

Environmental gamma-ray dose rates were measured by using ultra-high sensitive LiF:Mg,Cu,Si thermoluminescence dosimeters (TLDs) during short-term burial. The resultant gamma-ray dose rates were compared with those measured by using optically stimulated luminescence (OSL) of Al 2 O 3 :C and assessed by using HPGe spectrometer. Regardless of the short-term burial and the change of environmental conditions as well as the mismatch of the effective atomic number ( Z eff ) with the soil (mainly SiO 2 ), good agreement was observed between the doses measured by TLDs and OSL dosimeters or the assessed doses. LiF:Mg,Cu,Si TLD has been found to be an effective alternative for the measurement of environmental gamma-ray annual dose rates for use in optical dating.

We consider a population of subthreshold Izhikevich neurons that cannot fire spontaneously without noise. As the coupling strength passes a threshold, individual neurons exhibit noise-induced burstings (i.e., discrete groups or bursts of noise-induced spikes). We investigate stochastic bursting synchronization by varying the noise intensity. Through competition between the constructive and the destructive roles of noise, collective coherence between noise-induced burstings is found to occur over a large range of intermediate noise intensities. This kind of stochastic bursting synchronization is well characterized by using the techniques of statistical mechanics and nonlinear dynamics, such as the order parameter, the raster plot of neural spikes, the time series of the ensemble-averaged global potential, and the phase portraits of limit cycles. In contrast to spiking neurons showing only spike synchronization (characterizing a temporal relationship between spikes), bursting neurons are found to exhibit both spike synchronization and burst synchronization (characterizing a temporal relationship between the onset times of the active phases of repetitive spikings). The degree of stochastic bursting synchronization is also measured in terms of a synchronization measure that reflects the resemblance of the global potential to the individual potential.

Using a newly developed small X-ray irradiator equipped with a mini X-ray generator (Varian VF-50J) and TR-OSL measurement system attached to an MCS (ORTEC MCS-PCI), the influence of dose and dose rate of X-ray radiation on TR-OSL was investigated in paleosol quartz from the Chungdang-dong paleolithic site, Korea. All lifetimes were calculated by a curve-fitting method using a single stretched-exponential function with β = 0.86. Physical characteristics, natural lifetime, thermal quenching activation energy ΔE, and thermal assistance activation energy Ea were firstly determined. From the results of the investigation of dependence on dose and dose rate of X-ray radiation using fully bleached samples, the lifetime decreased significantly to about 20 μs; when the X-ray dose was increased to 300 Gy at a dose rate of 0.5 Gy/s. Also, despite different radiation dose rates, at a dose of 50 Gy both lifetime and related intensity were independent of dose rate change.

OSL dating on sedimentary quartz grains from two archaeological sites in Korea, called Hahwagye-ri and Hwadae-ri, was undertaken to aid archaeological interpretation for the migratory routes of the Upper Palaeolithic and Mesolithic people in Korea. The Hahwagye-ri site is located on a river terrace of the North Han river at Kangwon prefecture and the Hwadae-ri is located on a river terrace of the Imjin river at Gyeonggi prefecture, both in the central region of Korean Peninsula. From the results of excavation conducted for recent two years, archaeologists strongly suggest that these areas would be an ideal camping place with relatively long-term residence for the Palaeolithic and/or Mesolithic foragers to get food resources by means of collecting, fishing and hunting. In order to check the quartz OSL results on the sediments at those excavation sites, radiocarbon dating was also carried out on a small series of finely layered charcoal samples. The OSL ages obtained showed a good stratigraphic correlation and were found to be in satisfactory agreement with those of the radiocarbon dating, implying that the incomplete bleaching of quartz grains, which is usually observed from fluvially deposited sediments, is not significant for these samples. These consistent ages also suggest that the quartz OSL dating can provide reliable age estimates in case that there are not enough materials suitable for other conventional tools for dating archaeologically important sediment layers. The resultant ages may provide important and useful chronological information for the Upper Palaeolithic and Mesolithic culture in Korean.

Red thermoluminescence in quartz has been generally observed in samples from volcanic deposits or archaeological burnt materials. Red thermoluminescence emission quartz has gained attention as a radiation dosimeter for thermoluminescence dating due to the high-dose saturation level and long-term stability of the thermoluminescence signal. The technique for this application can be improved with an understanding of various trap parameters associated with thermoluminescence glow peaks. The repeated initial rise and computerized glow curve deconvolution methods are used to determine the number of thermoluminescence glow peaks and trap parameters for red thermoluminescence from two types of quartz (Tazawa and Yuda samples) from Japan. For both quartz samples, the glow curves were best described as a superposition of seven glow peaks with activation energies of 0.76–1.95 eV and 0.89–1.91 eV for the Tazawa and Yuda samples, respectively. These results provide useful information for the investigation of the intri...

The Suryum fault (F1) with subsidiary branches (F2, 3) varies in strike from N40°E to N14°E and in dip from

Red thermoluminescence (TL) emission from quartz has attracted considerable attention in the fields of retrospective dosimetry and luminescence dating, due to the high dose saturation level and long-term stability of the TL signal. For two red emission quartz samples of volcanic origin (Yuda sample from Iwate Prefecture and Tazawa sample from Akita Prefecture in Japan), we investigated the radiation dose response of TL glow peaks separated using a glow curve fitting method. The radiation dose response of the separated peaks was examined using a growth curve based on the SAR TL protocol. The 260 °C, 290 °C and 320 °C peaks for the Yuda sample and the 270 °C and 320 °C peaks for the Tazawa sample showed a supralinear response up to 300 Gy, whereas the 370 °C peak for both samples behaved linearly.

Compound semiconductors of high Z value material have been studied intensively for X-ray and γ -ray spectroscopy at room temperature. CdZnTe has wide band gap energy as 1.6 eV and can provide high quantum efficiency with reasonably good energy resolution at room temperature. This study is aimed at determining radionuclide analysis ability by measuring energy resolution of CZT detector which will be applied at nuclear material identification purpose. For experiment we used a CZT detector (5 × 5 × 5 mm3) which is manufactured by eV Products. We have performed our measurement at varied temperatures similar to the outdoor environment for the investigation about temperature dependence of energy resolution and peak centroid fluctuation of CZT detector by using gas cooling and Peltier cooling methods. In order to test radionuclide identification we used various radionuclide samples; plutonium, europium and other standard sources. Pulse height spectra were obtained by standard electronics which consists of a prea...

CZT detector is one of the most promising radiation detectors for hard X-ray and γ-ray measurement. The energy spectrum of CZT detector has to be simulated to optimize the detector design. A CZT detector was fabricated with dimensions of 5 × 5 × 2 mm3. A Peltier cooler with a size of 40 × 40 mm2 was installed below the fabricated CZT detector to reduce the operation temperature of the detector. Energy spectra of were measured with 59.5 keV γ-ray from 241Am. A Monte Carlo code was developed to simulate the CZT energy spectrum, which was measured with a planar-type CZT detector, and the result was compared with the measured one. The simulation was extended to the CZT detector with strip electrodes.

Red TL (RTL) emission quartz has potential benefit for luminescence dating, due to the high dose saturation level and long-term stability of the TL signal. Concerning the equivalent dose determination, we investigated whether the single aliquot regenerative-dose (SAR) TL protocol would be successful in the case of RTL quartz from Japan. For the investigation, simulation tests were undertaken using sets of RTL quartz which were given known laboratory beta doses. Four different beta doses and three preheating conditions with two kinds of RTL quartz samples were employed for the simulation. Among the preheating conditions used, the simulated equivalent dose values obtained by using preheating at 220 ∘ C for 10 s and 260 ∘ C for 10 s were shown to be in far better agreement with the given beta doses. In the beginning of the experiments, the samples were first heated to 500 ∘ C for 60 s prior to the administration of simulation beta doses, in order to remove any residual TL signal. Thus, in terms of dating natural quartz samples, the implications of our results are limited to the samples which have been affected by syn- or post-depositional heating (e.g. volcanic debris flows, overlying lava flows, etc.). Our simulation results show a possibility that the RTL quartz employed in this study is capable of being applied to the SAR approach. In addition, it seems feasible to extend the time range of luminescence dating well beyond the usual range by the conventional quartz OSL methods.

The asymmetrical distortion of the Cadmium Zinc Telluride ((CZT) energy spectrum is mainly caused by the hole trapping in the CZT crystal, and it can be characterized by the mean free path of hole. The mean free paths of the charge carriers in the CZT crystal can be extracted from fitting the peak shape of the measured energy spectrum. The energy spectra of γ-rays from 241 Am, and that of α particles from 238 Pu were measured with a CZT with 5×5×5 mm 3 . The mean free path of the electron was determined from the bias dependence of α-particle response. The energy spectra of γ-ray were simulated with EGSnrc code, in which Hecht equation was included, and the mean free path of the hole was determined by comparing the measured spectrum with the simulated one. The energy spectrum of 662 keV γ-ray was measured with the CZT detector, and it was compared with the simulated spectrum, in which newly determined mean free paths of the electron and the hole were used.

Luminescence excited by a small X-ray generator (Varian VF-50J) instead of the usual 90 Sr– 90 Y beta source was measured following optical stimulation. The optimal X-ray irradiation conditions have been assessed, including the irradiation dose rate and the thickness of Al-absorber, in the equivalent dose determination when a luminescence dating process is simulated with laboratory dosed quartz samples. The equivalent doses were found to greatly depend on both the thickness of Al-absorber and the X-ray dose rate. We suggest that the optimal X-ray irradiation conditions for accurate luminescence dating work can be obtained by applying the following: (i) use of an Al-absorber with a thickness of 200 μm and (ii) X-ray dose rates of 0.38 Gy/min to 2.9 Gy/min.

We present a self-constructed immunosensor with angular interrogation-based-surface plasmon resonance (SPR) spectroscopy in order to analyse antigen–antibody interactions. The SPR intensity, resonance angle and full width at half maximum (FWHM) were significantly affected by the thickness of an Au film. The optimal thickness for the Au film thickness as an active metal for surface plasmons was determined to be approximately 45 nm, as respects the SPR intensity and the FWHM of SPR spectrum. The detection limit of the sensor based on the minimal refractive index variation was found to be 1.4 × 10−4. The interaction of C-reactive protein (CRP) with anti-CRP on a 45 nm Au film was successfully analysed with the self-constructed SPR sensor. We suggest that the SPR sensor can be used as a useful tool for the analysis of immunoreactions.

Thermoluminescence (TL) dating of volcanic rocks and pumice flows around Onikobe-Naruko area was carried out by checking suitability of the sample for this technique. Samples for TL dating were divided into three ranks, A, B and C, on the basis of physical/petrographical characters and geological origin. Rank A sample is hard and compact rock which is chemically stable. Rank B is soft pumice flow or equivalent sample which is chemically unstable for long geologic time. Rank C is sediment deposited in water. For precise and reliable TL dating, only rank A sample must be used. TL ages obtained from samples of rank A are 30.4 ka for Naruko dome lava, 187 ka for Takahinatayama lava, 169 ka and 170 ka for Shimoyamazato Tuff Formation, and 296 ka and 268 ka for Ikezuki Tuff Formation. Mitsuzawa Formation at western part of Naruko, pyroclastic flows at Yubama and Byobuiwa are identified as Ikezuki Tuff Formation due to their TL ages of 258 ka, 231 ka to 345 ka and 238 ka, respectively. TL ages of two sites are not well coincide to Ikezuki Tuff Formation. TL ages of the samples from Yubama Onsen and Gyojadaki are 169 ka and 362 ka, which correspond to the age of other eruption products rather than Ikezuki Tuff Formation. TL age data for 83 samples of rank B and C are checked by comparison with those of rank A and existence age data. It could be reconciled with stratigraphic evidence and corresponding ages of rank A. Rank B and C data are selectively apply for preliminary stage or special purposes that the rough ages are still useful for research program.

The time-integrated slip rate in fault zones can be determined if the deformed deposits are reliably dated. Here, we report optically stimulated luminescence (OSL) ages of Late Pleistocene fluvial deposits cut by the Wangsan fault, southeastern Korea, which displaces a hanging wall block of about 28 m. Five sandy samples of the deformed Quaternary deposits were dated by quartz OSL using the single aliquot regenerative-dose (SAR) protocol. Three samples taken from the footwall block show stratigraphically consistent OSL ages of 54±7, 76±5 and 90±6 ka, from top to bottom. Two samples collected from the same layer in the hanging wall block show reproducible OSL ages of 81±5 and 82±5 ka, which are also in good agreement with the stratigraphic relationships. Our OSL ages yield an average sedimentation rate of the Quaternary deposits as around 0.04 mm a −1 , and a minimum value of time-integrated slip rate as 0.52 mm a −1 . This minimum slip rate is considerably higher than those reported earlier for Quaternary faults in southeastern Korea. The youngest OSL age (54±7 ka) constrains the maximum value of the recurrence interval of the fault movement.

Luminescence dating using infrared stimulation of K-feldspar grains was undertaken to determine the sedimentation rate of a recently deposited tidal flat on the western coast of Korea. Five samples were collected from a core of the tidal flat. The very low luminescence intensities in the surface sample indicate that the material was well bleached at deposition. Recuperation before and after preheating was investigated on natural and laboratory-bleached surface samples and considered in age calculations. The five IRSL age estimates show a reasonable stratigraphic correlation and allow the calculation of the sedimentation rate of 6.1±0.4 cm yr −1 . We conclude that infrared stimulated luminescence dating can contribute significantly to the determination of sedimentation rates of tidal flats.

Several sets of marine terraces are exposed along the southeastern coast of the Korean peninsula. The formation ages of these terraces have attracted considerable attention because they provide essential information on local crustal stability. Over the last few years considerable effort has been put into the determination of these ages using optically stimulated luminescence (OSL) dating of the marine sediments from which the terraces were built. For several sites, the results of dose recovery tests and other OSL characteristics, including the dependence of equivalent dose on heat treatment prior to stimulation, have been described in detail elsewhere (Quat. Sci. Rev. 22 (2003) 407). However, it has been found that the samples from one site exhibit various undesirable OSL characteristics, which result in stratigraphically inconsistent OSL ages. In this paper, we investigate these characteristics, and use luminescence component separation to resolve this inconsistency. The resolved OSL ages obtained as such are then used for the discussion on the local crustal stability of the southeastern coast of Korea during the Late Pleistocene.

We investigated the surface characteristics of antibody binding on protein chips with resonance wavelength-based spectral surface plasmon resonance (SPR) imaging. The fluctuation of the resonance wavelengths for gold and dithiobis (succinimidyl propionate) (DTSP) array spots were less than 0.4 nm, which was good enough to analyze biomolecular interactions on the arrays. A serial process of biomolecular interactions from gold to anti-C-reactive protein (CRP) on the protein chips was monitored by the spectral SPR imaging. SPR images showed that distribution of anti-CRP binding onto the CRP surface was not uniform. Changes of color in the two-dimentional SPR images were explained by variations of the refractive index caused by differences in the amount of bound anti-CRP on protein chips. These results suggest that the spectral SPR imaging can be used as a novel tool for the analysis of surface distribution of protein binding with a label-free format.

Several flights of marine terraces can be identified along the southeastern coast of Korea. In the Yonghan area, the northern part of this coastline, three sets of marine terraces are usually identifiable; NQt 1 (ca. 4 m), NQt 2 (ca. 15 m) and NQt 3 (ca. 35 m). Aeolian dune sands are well preserved on top of each terrace surface, underlain by palaeo-beach sediments. After various performance tests of the applicability of the single-aliquot regenerative-dose (SAR) protocol (e.g. preheat plateau, dose recovery and thermal transfer tests) we obtained quartz optically stimulated luminescence (OSL) ages ranging between 64±6 and 127±12 ka (NQt 3 ), 51±2 and 80±4 ka (NQt 2 ), and 0.09±0.01 and 0.11±0.01 ka (NQt 1 ) from aeolian dune sands and underlying palaeo-beach sediments on each terrace, all of which appear to be consistent with the established palaeo-sea level record. Of these, the OSL ages of the palaeo-beach sediments from NQt 3 (127 ka) and NQt 2 (73–80 ka) indicate that these terraces were formed during marine isotopic stage (MIS) 5e and MIS 5a, respectively. We obtained quartz SAR OSL ages of 68±4–92±11 ka from sandy gravel layers collected from the Suryum site (MQt 4 terrace, ca. 45 m), where Quaternary faults crosscut the MQt 4 terrace. These data, however, do not show an internal consistency in stratigraphic order, and significantly underestimate the expected timing of emergent interglacial high sea stands. Although the reasons for the inconsistency in OSL ages of the samples from the Suryum site (MQt 4 terrace) are not well known as yet, the OSL ages of other terrace sediments (the NQt 2 , NQt 3 and MQt 2 terraces) imply that, unlike the conventional view, the southeastern part of Korean peninsula has not been tectonically very stable during the Late Pleistocene.

A novel method for sensitivity enhancement of spectral surface plasmon resonance (SPR) biosensors was presented by reducing the refractive index of the sensing prism in the analysis of protein arrays. Sensitivity of spectral SPR biosensors with two different prisms (BK-7, fused silica) was analyzed by net shifts of resonance wavelength for specific interactions of GST-GTPase binding domain of p21-activated kinase-1 and anti-GST on a mixed thiol surface. Sensitivity was modulated by the refractive index of the sensing prism of the spectral SPR biosensors with the same incidence angle. The sensitivity of a spectral SPR biosensor with a fused silica prism was 1.6 times higher than that with a BK-7 prism at the same incidence angle of 46.2 degrees. This result was interpreted by increment of the penetration depth correlated with evanescent field intensity at the metal/dielectric interface. Therefore, it is suggested that sensitivity enhancement is readily achieved by reducing the refractive index of the sensing prism of spectral SPR biosensors to be operated at long wavelength ranges for the analysis of protein arrays.

We have investigated whether surface plasmon resonance (SPR) sensors based on the wavelength interrogation are able to analyze protein interactions on protein arrays. The spectral SPR sensor was self-constructed and its detection limit, expressed as the minimal refractive index variation, was calculated to be 6.6x10(-5) with the signal fluctuation of 1.0x10(-5). The protein array surface was modified by a mixed thiol monolayer to immobilize proteins. Protein arrays were analyzed by the line-scanning mode of the SPR sensor, which scanned every 100 microm along the central line of array spots and the scanned results were presented by color spectra from blue to red. Glutathione S-transferase (GST)-rac1 caused a concentration-dependent increase of SPR wavelength shift on protein arrays. The surface structure of the protein arrays was analyzed by atomic force microscopy. Specific interactions of antigens with antibodies were analyzed on the protein arrays by using three antibodies and eight proteins. These results suggest that the wavelength interrogation-based SPR sensor can be used as the biosensor for the high-throughput analysis of protein interactions on protein arrays.

We study inhibitory coherence (i.e. collective coherence by synaptic inhibition) in a population of globally coupled type-I neurons, which can fire at arbitrarily low frequency. No inhibitory coherence is observed in a homogeneous population composed of only subthreshold neurons, which exhibit noise-induced firings. In addition to subthreshold neurons, there exist spontaneously firing suprathreshold neurons in a noisy environment of a real brain. To take into consideration the effect of suprathreshold neurons on inhibitory coherence, we consider a heterogeneous population of subthreshold and suprathreshold neurons and investigate the inhibitory coherence by increasing the fraction of suprathreshold neurons Psupra. As Psupra passes a threshold P*supra, suprathreshold neurons begin to synchronize and play the role of coherent inhibitors for the emergence of inhibitory coherence. Thus, regularly oscillating population-averaged global potential appears for Psupra > P*supra. For this coherent case, suprathreshold neurons exhibit sparse spike synchronization (i.e. individual potentials of suprathreshold neurons consist of coherent sparse spikings and coherent subthreshold small-amplitude hoppings). By virtue of their coherent inhibition, sparsely synchronized suprathreshold neurons suppress the noisy activity of subthreshold neurons. Thus, subthreshold neurons exhibit hopping synchronization (i.e. only coherent subthreshold hopping oscillations without spikings appear in the individual potentials of subthreshold neurons). We also characterize the inhibitory coherence in terms of the ?statistical-mechanical? spike-based and correlation-based measures, which quantify the average contributions of the microscopic individual spikes and individual potentials to the macroscopic global potential. Finally, the effect of sparse randomness of synaptic connectivity on the inhibitory coherence is briefly discussed.

(2002). An Automated System for Both Red/Blue Thermoluminescence and Optically Stimulated Luminescence Measurement. Journal of Nuclear Science and Technology: Vol. 39, No. 1, pp. 108-109.

For quartz stimulated by green light, several comparisons are presented between traditional multiple aliquot results and corrected single aliquot measurements. The dependence of the luminescence response on added dose is compared for two techniques and it is found that the closeness of similarity depends on the preheating used. For naturally dosed samples, the comparisons are made both for materials that were originally zeroed by heating and others originally bleached by exposure to light. Three alternative single aliquot correction procedures are used.