To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure email@example.com
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Sleep restriction has adverse effects on performance and neurobehavioral function. However, the mechanism of impaired performance and neurobehavioral function has not been studied yet.
We examined the effect of insufficient sleep on cerebral blood flow and cognitive function in 8 healthy adults (mean age 22.4 years).
All participants were in bed for 8 h (sufficient sleep), and for < 4 h (insufficient sleep). The oxyhemoglobin (oxyHb) level by a word fluency task was measured with a near-infrared spectroscopy recorder on the morning following sufficient and insufficient sleep periods. Wisconsin card sorting test (WCST), continuous performance test (CPT) and N-back test were evaluated on the same days.
The peak oxyHb level was significantly lower in the left and right frontal lobes after insufficient sleep than after sufficient sleep (left: 0.25 ± 0.10 vs. 0.70 ± 0.29 mmol, P < 0.05; right: 0.23 ± 0.13 vs. 0.73 ± 0.22 mmol, P < 0.05). There was no significant difference in the number of words generated during the word fluency task between sufficient and insufficient sleep states. The percentage of correct responses on CPT after insufficient sleep was significantly lower than that after sufficient sleep (86.6 ± 10.2 vs. 96.0 ± 4.9%, P < 0.05). The reaction time of WCST was significantly longer after insufficient sleep than after sufficient sleep (76.6 ± 13.4 vs. 70.6 ± 16.2 sec, P < 0.05).
One night sleep restriction decreased the concentration changes of oxyHb in brain tissue, leading to impaired cognitive function.
Chronic sleep restriction results from a number of factors; medical condition and social demands, and has adverse effects on daytime function, such as cognitive function and driving performance. We demonstrated that the acute sleep restriction (time in bed < 4 h/night) impaired cortical oxygenation response during word fluency task.
We examined the chronic effect of insufficient sleep on cerebral blood flow and cognitive function.
Ten healthy adults (mean age 19.0 years, mean BMI 22.5 kg/m2) were enrolled in this study. All participants spent > or = 8 h/night in bed prior to study day (sufficient sleep), followed by < 4 h/night in bed for 3 days (insufficient sleep1, 2 and 3). The oxyhemoglobin (oxyHb) level by a word fluency task was measured with a near-infrared spectroscopy recorder on the morning following sufficient and insufficient sleep 1 and 3. Wisconsin card sorting test (WCST), continuous performance test -identical pairs version (CPT-IP) and 2-back test were evaluated on the same day.
The peak oxyHb during the word fluency task was significantly reduced after insufficient sleep 1 and 3 than that after sufficient sleep. The percentage of correct responses on CPT-IP and 2- back test after insufficient sleep 3 were lower than those after sufficient sleep, though there were no significant differences on those. WCST did not significantly differ among insufficient sleep 1 and 3 and sufficient sleep.
The chronic sleep restriction reduced cortical oxygenation response, and might result in cognitive performance impairment.
Metal Organic Decomposition (MOD)-made BaTiO3 (BT) thin films were prepared for Resistive Random Access Memory (ReRAM) under various annealing conditions and investigated for improving the properties of bipolar-type resistive switching, focusing on the relation between oxygen vacancies and the behavior of resistive hysteresis. BT thin films with both pre- and final- annealing in nitrogen showed the resistive hysteresis of bipolar-type switching with current ON/OFF ratios of 2 orders of magnitude for both bias polarities. Finally they showed the endurance property with the 106 switching cycles. It was suggested that oxygen vacancies near the oxide surface (both interfaces at metal electrode/oxide and between layer-by-layered oxide layers) are increased by N2 annealing and enhanced the interface-type resistive switching. Pre-annealing in N2 was also found to be very effective to improve endurance properties, implying that not only the electrode/oxide interface but also the middle part of the film would contribute the interface-type mechanism.
Depression is one of the most prevalent mental illnesses worldwide and a leading cause of disability, especially in the setting of treatment resistance. In recent years, repetitive transcranial magnetic stimulation (rTMS) has emerged as a promising alternative strategy for treatment-resistant depression and its clinical efficacy has been investigated intensively across the world. However, the underlying neurobiological mechanisms of the antidepressant effect of rTMS are still not fully understood. This review aims to systematically synthesize the literature on the neurobiological mechanisms of treatment response to rTMS in patients with depression. Medline (1996–2014), Embase (1980–2014) and PsycINFO (1806–2014) were searched under set terms. Three authors reviewed each article and came to consensus on the inclusion and exclusion criteria. All eligible studies were reviewed, duplicates were removed, and data were extracted individually. Of 1647 articles identified, 66 studies met both inclusion and exclusion criteria. rTMS affects various biological factors that can be measured by current biological techniques. Although a number of studies have explored the neurobiological mechanisms of rTMS, a large variety of rTMS protocols and parameters limits the ability to synthesize these findings into a coherent understanding. However, a convergence of findings suggest that rTMS exerts its therapeutic effects by altering levels of various neurochemicals, electrophysiology as well as blood flow and activity in the brain in a frequency-dependent manner. More research is needed to delineate the neurobiological mechanisms of the antidepressant effect of rTMS. The incorporation of biological assessments into future rTMS clinical trials will help in this regard.
Good outcomes have been reported regarding the use of cochlear implants for mumps deafness. The mumps virus induces meningitis and/or encephalitis, which can cause central nervous system damage resulting in retrolabyrinthine hearing loss, for which a cochlear implant would be less effective.
We installed a cochlear implant in two patients with bilateral mumps deafness; one achieved a good result with the cochlear implant, but the other did not. We discuss two possible reasons for the different outcomes. Case 1 was a three-year-old girl with bilateral parotid swelling, vomiting and walking disorder. One year after cochlear implant insertion, speech perception did not develop despite of good pure tone thresholds. Case 2 was an eight-year-old girl with bilateral parotid swelling. A cochlear implant enabled her to improve hearing perception.
Although cochlear implants have been reported to be helpful for mumps deafness, cases that involve central nervous system damage may not achieve good results.
We examined 20 300 raw shell chicken eggs sold at retail stores in Japan for Salmonella outside and inside eggs. The eggs were purchased at 220 retail stores throughout Japan between August 2007 and January 2008. Of 2030 pooled egg samples (10 eggs/sample), Salmonella was isolated from five shell samples (0·25%), but not from any of egg-content samples. The serovars of the isolates were Salmonella Enteritidis (2), S. Derby, S. Livingstone and S. Cerro. The samples positive for Salmonella originated from five different egg grading and packaging (GP) centres. All the GP centres washed their egg shells according to government guidelines for hygienic practice in GP centres. Thus, practical control measures at GP centres need to be reviewed and implemented to diminish Salmonella prevalence of egg shells because Salmonella contamination on eggs is a potential hazard for foodborne salmonellosis in Japan.
We introduce the lasing principle and important characteristics of photonic-crystal surface-emitting laser (PC-SELs). Specifically, we demonstrate two-dimensional coherent lasing oscillation with GaN PC-SELs, using a unique crystal growth technique called “air hole retained overgrowth” (AROG). Above the threshold, we obtained a two-dimensionally distributed near-field pattern, and a distinctive far-field pattern with a divergence angle less than 1°. We also investigate a suitable sample structure for the reduction of the threshold current, where the PC structure is moved from an n-cladding layer to a p-cladding one. This is an important step towards the realization of novel light sources that can be integrated two dimensionally for a variety of new scientific and engineering applications in the blue to ultraviolet wavelengths.
The Microlensing Observations in Astrophysics (MOA) is a microlensing survey conducted at Mt. John Observatory in New Zealand. We searched transiting planet candidates from the MOA-I Galactic bulge data, which have been obtained with a 61cm B&C telescope from 2000 to 2005 for a microlensing search. Although this survey data were dedicated to microlensing, they are also quite useful for searching transiting objects because of the large number of stars monitored (~7 million) and the long span of the survey (~6 years). From our analysis, we found 58 transiting planet candidates. We are planning to follow up these candidates with high-precision spectroscopic and photometric observations for further selection, toward the detection of planets by radial velocity observations.
The tactile sensors for human support robots which can detect both normal stress and shear stress and have human-friendly surface have been proposed. Micro-cantilevers adequately inclined by Cr deflection control layer were fabricated by the surface micromachining on SOI wafer. The cantilevers were covered with the PDMS elastomer for human-friendly surface. When the stress is added to the surface of elastomer, the deformation of cantilevers along with elastomer is detected as piezoresistive layer in the cantilevers. The piezoresistive response of the cantilever is analyzed by FEM calculation. The response of the fabricated tactile sensor to normal stress and shear stress was measured by output from this resistance. The tactile sensor with PDMS elastomer can detect both normal stress and shear stress. On the other hand, it hardly has sensitivity to shear stress of orthogonal direction to the cantilever. It means that the tactile sensor can distinguish the direction of shear stress. The sensitivity of tactile sensor vary widely with cantilever pattern and relation between direction of cantilever and crystallite orientation of Si. It is suggested that the sensitivity of tactile sensor can be improved by using FEM estimation and selective ion implantation.
Photocatalytic hydrogen production with gas-phase reactions in high vacuum was examined for nanocrystalline anatase-type titanium dioxide (TiO2) thin films. The hydrogen generation process on platinized TiO2 specimens was investigated using a quadrupole mass spectrometer at a real-time scale under various partial pressures of gaseous methanol and water. As a result, hydrogen generation was successfully detected under ultraviolet ray (UV) illumination even in high vacuum (∼ 10−7 Torr). And the amount of produced H2 largely depends on the temperature of TiO2 samples, probably due to different surface states of TiO2. This study suggests the possibility of new high-speed H2 production system with gas-phase photocatalytic reactions.
We have developed a new silicon nitride (SiNx) multilayer barrier film by a plasma-enhanced chemical vapor deposition (CVD) for a flexible organic light emitting diode (OLED), which consists of SiNx films in two different deposition conditions, that is, a transparent SiNx layer (tr-SiNx) deposited with NH3 gas and an ultra-thin SiNx layer (cap-SiNx) deposited without NH3 gas, which caps over the former layer. This barrier film is expected to exhibit high durability under high temperature and high humidity conditions even at high deposition rate over 100 nm / minute, because the transparent SiNx layer, that is easily oxidized under such conditions, is protected by the cap-SiNx layer and the interface between them, and also show good transparency, because the opaque cap-SiNx layer is enough thin to be almost transparent to visible light. Thus, the multi-layer SiNx barrier film indicates the specific features as a high barrier performance, high transparency, and high productivity, and makes it possible to apply flexible OLED displays to automobile use.
We observed a preformed plasma of an aluminum slab target produced by a high-intensity Ti:sapphire laser. The expansion length of the preformed plasma at the electron density of 3 × 1018 cm−3, which was the detection limit, was around 100 μm measured with a laser interferometer. In order to characterize quantitatively and to control the preformed plasmas, we perform a two-dimensional hydrodynamic simulation. The expansion length of the preformed plasma was almost the same as the experimental result, if we assumed that the amplified spontaneous emission lasted 3.5 ns before the main pulse arrived.
The Cr/Si bilayer cantilevers for an integrated multi-axis tactile sensor were fabricated by Si surface micromachining process. Among the cantilevers with various shapes, the rectangular and semicircular cantilevers can be deflected upward with good controllability. The maximum deflections are compared with those calculated by finite element method. Calculated deflections of Cr/Si cantilever agree considerably with the measured one. So, it is considered that the analysis by finite element method is useful as optimization of layer thickness and size to obtain the Cr/Si bilayer cantilevers with accurate deflection.
The light curves for three eclipsing binaries in the Magellanic Clouds have been obtained using CCD uVJIC photometry. One target in the LMC, MACHO*05:36:48.7−69:17:00, is an eccentric system, e = 0.20, with a period of 3.853534 ± 0.000005 d. Initial solutions indicate a primary component in the range Teff,1 = 20,000−35,000K and the secondary Teff,2 1000−2000K cooler than the primary, with inclinations ranging i = 84.2° − 86.0°. Two targets in the SMC, MOA J005018.4-723855 and MOA J005623.5−722123, have periods of 1.8399±0.0004 and 2.3199 ± 0.0003 days respectively. Both have circular orbits with the former being a semi-detached system.
More than 4000 stars observed in both MOA and DENIS projects showing periodic or quasi-periodic light curves are studied. Almost all Mira stars are located on the classical period-luminosity relation, and the multiplicity of the period-luminosity relation is confirmed for small-amplitude stars. The colour-magnitude diagrams based on the MOA red band, Rm, and Ks constructed for the sequences, form a single strip with small successive shifts.
Natural-superlattice-structured Bi3TiNbO9–Bi4Ti3O12 (m =2–3) (BTN–BIT) films have been grown on Pt/TiO2/SiO2/Si substrates at 400 °C to 550 °C by pulsed laser deposition (PLD) using BTN–BIT (1 mol:1 mol) target, and were post-annealed in O2 for 45 minutes at 750 °C. BTN–BIT films prepared above 500 °C have single phase whose c lattice parameter is estimated to 8.300 nm in consideration of periodicity of lattice structures. This lattice constant is very close to the value (8.316 nm) of that of two unit cells of BTN and one unit cell of BIT, that is 2–1 superlattice structure of BTN–BIT. The BTN–BIT film with 2–1 superlattice structure has large remanent polarization (2Pr = 50 μC/cm2) and large coercive field (2Ec= 350 kV/cm). La-doped BTN–BIT thin film has also large remanent polarization (2Pr = 52 μC/cm2) and relatively small coercive field (2Ec= 220 kV/cm). The La-doped BTN–BIT film is fatigue-free on Pt electrodes up to 1010 switching cycles.
Neodymium-modified Bi4Ti3O12(BNdT) thin films have been prepared by pulsed laser deposition (PLD), aiming to realize enhanced ferroelectric properties by a low temperature treatment. When deposited at 500°C, the film shows P-E hysteresis having twice remanent polarization 2Pr of 78.8 μC/cm-2, coercive force Ec of about 250 kV/cm, and leakage current of less than 10-7 A/cm2 from -50 to +50 kV/cm. Good fatigue properties of BNdT films deposited at 5 Hz have been obtained up to 1010 cycles of 500 kHz bipolar square pulses, with less than 25% decrease of +Pr and -Pr.
BiFeO3 thin film has been prepared on Pt/TiO2/SiO2/Si substrate at a temperature as low as 450°C by pulsed-laser deposition. The BiFeO3 thin film is perovskite single-phase, while any nonperovskite phase, such as orthorhombic Bi2Fe4O9, is not included. Dielectric constant of the film is 87, dielectric loss is 0.03, and leakage current density is low. The coexistence of ferroelectricity and ferromagnetism has been confirmed by means of the P-E and M-H hysteresis characteristics. The BiFeO3 thin film shows a well-saturated hysteresis loop with twice the remanent polarization 2Pr = 54 μC/cm2 and coercive field 2Ec = 100 kV/cm for a maximum applied electric field of 100 kV/cm, and also shows a saturated weak ferromagnetic hysteresis loop, as well as a small remanent magnetization with 2Mr = 0.6 emu/cm3 and 2 Hc = 200 Oe for a maximum magnetic field of 10 kOe at room temperature.
The structural and the optical properties of 10-period In0.15Ga0.85N/GaN multiple quantum wells (MQWs) have been investigated using HRXRD (high-resolution X-ray diffraction) and PL (photoluminescence). For the samples, the barrier thickness was kept constant, 7.5 nm and the well thicknesses were varied, 1.5, 3.0, 4.5, and 6.0 nm. For the structural characterization, an ω/2θ-scan and an ω-scan for GaN (00 2) reflection and a reciprocal space mapping (RSM) around the GaN (10 5) lattice point were employed. The average strain for the MQWs increased as the well thickness increased. The MQW with a 6.0 nm well thickness experienced lattice relaxation and the crystallinity of the sample was poor compared to that of the other samples. MQWs with well thicknesses of 1.5, 3.0 and 4.5 nm, however, maintained lattice coherency with the GaN epilayers underneath, and the critical well thickness for lattice relaxation of the MQWs used in the study was 6.0 nm. The PL spectra showed that the relative emission intensity of the sample with a 6.0 nm well thickness was lower than for the others, a fact consistent with the X-ray results. The emission intensity, therefore, is considered to be affected by defects due to lattice relaxation of the epilayer.
By means of a systematic study carried out on In0.5Ga0.5As/GaAs quantum dot electroluminescent devices grown by Metal Organic Chemical Vapor Deposition, we show that the combination of internal electric fields in such structures dramatically blue shifts the emission wavelength with respect the photoluminescence emission that occurs at the expected value of 1.3 νm at room temperature. By comparing photoluminescence (PL), electroluminescence (EL) and photocurrent (PC) measurements in In0.5Ga0.5As QD structures emitting between 1.28 νm and 1.4 νm (at 300 K), we demonstrate that the electric field associated to the built-in dipole in the dots, directed from the base of the dots to their apex, and the device junction field (when parallel to the dipole field) lead to the depletion of the ground state. As a consequence, structures grown on n-type GaAs substrates exhibit electroluminescence only from the excited states. Instead, by growing the same device structure on p-type GaAs substrates, i.e. by reversing the direction of the built-in electric field of the device, the effect of the permanent dipole is strongly reduced, thus allowing us to obtain EL emission at the designed wavelength of 1.3 νm at 300 K, coincident to the PL. The consequence on the achievement of efficient lasing in the spectral region of interest for optical transmission. are illustrate.