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In conventional stereotactic radiosurgery (SRS), treatment of multiple brain metastases using multiple isocenters is time-consuming resulting in long dose delivery times for patients. A single-isocenter technique has been developed which enables the simultaneous irradiation of multiple targets at one isocenter. This technique requires accurate positioning of the patient to ensure optimal dose coverage. We evaluated the effect of six degrees of freedom (6DoF) setup errors in patient setups on SRS dose distributions for multiple brain metastases using a single-isocenter technique. We used simulated spherical gross tumor volumes (GTVs) with diameters ranging from 1.0 to 3.0 cm. The distance from the isocenter to the target's center was varied from 0 to 15 cm. We created dose distributions so that each target was entirely covered by 100% of the prescribed dose. The target's position vectors were rotated from 0 degrees-2.0 degrees and translated from 0-1.0 mm with respect to the three axes in space. The reduction in dose coverage for the targets for each setup error was calculated and compared with zero setup error. The calculated margins for the GTV necessary to satisfy the tolerance values for loss of GTV coverage of 3% to 10% were defined as coverage-based margins. In addition, the maximum isocenter to target distance for different 6DoF setup errors was calculated to satisfy the tolerance values. The dose coverage reduction and coverage-based margins increased as the target diameter decreased, and the distance and 6DoF setup error increased. An increase in setup error when a single-isocenter technique is used may increase the risk of missing the tumor; this risk increases with increasing distance from the isocenter and decreasing tumor size.

Purpose To investigate the dosimetric impact between the anisotropic analytical algorithm (AAA) and the Acuros XB (AXB) algorithm in volumetric-modulated arc therapy (VMAT) plans for high-grade glioma (HGG). Methods We used a heterogeneous phantom to quantify the agreement between the measured and calculated doses from the AAA and from the AXB. We then analyzed 14 patients with HGG treated by VMAT, using the AAA. We newly created AXB plans for each corresponding AAA plan under the following conditions: (1) re-calculation for the same number of monitor units with an identical beam and leaf setup, and (2) re-optimization under the same conditions of dose constraints. The dose coverage for the planning target volume (PTV) was evaluated by dividing the coverage into the skull, air, and soft-tissue regions. Results Compared to the results obtained with the AAA, the AXB results were in good agreement with the measured profiles. The dose differences in the PTV between the AAA and re-calculated AXB plans were large in the skull region contained in the target. The dose difference in the PTV in both types of plan was significantly correlated with the volume of the skull contained in the target (r = 0.71, p = 0.0042). A re-optimized AXB plan's dose difference was lower vs. the re-calculated AXB plan's. Conclusions We observed dose differences between the AAA and AXB plans, in particular in the cases in which the skull region of the target was large. Considering the phantom measurement results, the AXB algorithm should be used in VMAT plans for HGG.

There are no quantitative selection criteria for identifying high-grade glioma (HGG) patients who are suited for volumetric-modulated arc therapy (VMAT). This study aimed to develop selection criteria that can be used for the selection of the optimal treatment modality in HGG. We analyzed 20 patients with HGG treated by 3D conformal radiotherapy (3DCRT). First, VMAT plans were created for each patient retrospectively. For each plan, the normal tissue complication probability (NTCP) for normal brain was calculated. We then divided the patients based on the NTCPs of the 3DCRT plans for normal brain, using the threshold of 5%. We compared the NTCPs of the two plans and the gross tumor volumes (GTVs) of the two groups. For the GTVs, we used receiver operating characteristic curves to identify the cut-off value for predicting NTCP < 5%. We determined the respective correlations between the GTV and the GTV’s largest cross-sectional diameter and largest cross-sectional area. In the NTCP ≥ 5% group, the NTCPs for the VMAT plans were significantly lower than those for the 3DCRT plans (P = 0.0011). The NTCP ≥ 5% group’s GTV was significantly larger than that of the NTCP < 5% group (P = 0.0016), and the cut-off value of the GTV was 130.5 cm3. The GTV was strongly correlated with the GTV’s largest cross-sectional diameter (R2 = 0.82) and largest cross-sectional area (R2 = 0.94), which produced the cut-off values of 7.5 cm and 41 cm2, respectively. It was concluded that VMAT is more appropriate than 3DCRT in cases in which the GTV is ≥130.5 cm3.

We characterize single nitrogen-vacancy (NV) centers created by 10-keV N+ ion implantation into diamond via thin SiO$_2$ layers working as screening masks. Despite the relatively high acceleration energy compared with standard ones (< 5 keV) used to create near-surface NV centers, the screening masks modify the distribution of N$^+$ ions to be peaked at the diamond surface [Ito et al., Appl. Phys. Lett. 110, 213105 (2017)]. We examine the relation between coherence times of the NV electronic spins and their depths, demonstrating that a large portion of NV centers are located within 10 nm from the surface, consistent with Monte Carlo simulations. The effect of the surface on the NV spin coherence time is evaluated through noise spectroscopy, surface topography, and X-ray photoelectron spectroscopy., 10 pages, 8 figures. To appear in Journal of Applied Physics (Special Topics on Materials for Quantum Technologies: Computing, Information, and Sensing)

Purpose We evaluated the setup accuracy of a three‐degree‐of‐freedom fiducial marker (3DOF‐FM)‐based setup compared to a soft tissue (ST)‐based setup in hypofractionated intensity‐modulated radiotherapy (IMRT) for prostate cancer. Materials and Methods We analyzed the setup accuracy for 17 consecutive prostate cancer patients with three implanted FMs who underwent hypofractionated IMRT. The 3DOF‐ST‐based setup using cone‐beam computed tomography (CT) was performed after a six DOF‐bony structure (BS)‐based setup using an ExacTrac x‐ray system. The 3DOF‐FM‐based matching using the ExacTrac x‐ray system was done during the BS‐ and ST‐based setups. We determined the mean absolute differences and the correlation between the FM‐ and ST‐based translational shifts relative to the BS‐based setup position. The rotational mean shifts detected by the ExacTrac x‐ray system were also evaluated. Results The mean differences in the anterior‐posterior (AP), superior‐inferior (SI), and left‐right (LR) dimensions were 0.69, 0.0, and 0.30 mm, respectively. The Pearson correlation coefficients for both shifts were 0.92 for AP, 0.91 for SI, and 0.68 for LR. The percentages of shift agreements within 2 mm were 85% for AP, 93% for SI, and 99% for LR. The absolute values of rotational shifts were 0.1° for AP, 0.3°, and 1.2° for LR. Conclusions The setup accuracy of the 3DOF‐FM‐based setup has the potential to be interchangeable with a ST‐based setup. Our data are likely to be useful in clinical practice along with the popularization of the hypofractionated IMRT in prostate cancer.

We study Bell-state correlations for quasiparticle pairs excited in nonlinear current through a double quantum dot in the Kondo regime. Exploiting the renormalized perturbation expansion in the residual interactions of the local Fermi liquid and Bell's inequality for cross correlation of spin currents through distinct conduction channels, we derive an asymptotically exact form of Bell's correlation for the double dot at low bias voltages. We find that pairs of quasiparticles and holes excited by the residual exchange interaction violate Bell's inequality for the spin currents.

We investigated the outcomes of treatment for patients with localized prostate cancer (PCa) treated with 3D conformal radiation therapy (3D-CRT) followed by two-fraction high-dose-rate brachytherapy within a single day (2-fr.-HDR-BT/day) at a single institution. A total of 156 consecutive Asian males (median age, 67 years) were enrolled. To compare our findings with those of other studies, we analyzed our results using the D'Amico classification, assigning the patients to low- ( n = 5; 3.2%), intermediate- ( n = 36; 23.1%) and high-risk ( n = 115; 73.7%) groups (Stage T3 PCa patients were classified as high-risk). One patient in the D'Amico low-risk group (20%), 13 intermediate-risk patients (36.1%) and 99 high-risk patients (86.1%) underwent androgen deprivation therapy. We administered a prescription dose of 39 Gy in 13 fractions of 3D-CRT combined with 18 Gy of HDR-BT in two 9-Gy fractions delivered within a single day. We did not distinguish between risk groups in determining the prescription dose. The median follow-up period was 38 months. Of the 156 patients, one died from primary disease and five died from other diseases. The 3-year overall survival (OS) rates were 100%, 100% and 93.7%, and the 3-year ‘biochemical no evidence of disease (bNED)’ rates were 100%, 100% and 96.9% for the D'Amico low-, intermediate- and high-risk groups, respectively. No patient developed ≥ Grade 3 early toxicity. The Grade 3 late genitourinary toxicity rate was 2.6%, and no ≥ Grade 3 late gastrointestinal toxicity occurred. The efficacy and safety of this study were satisfactory, and longer-term follow-up is necessary.

We report on a nanoscale quantum-sensing protocol which tracks a free precession of a single nuclear spin and is capable of estimating an azimuthal angle---a parameter which standard multipulse protocols cannot determine---of the target nucleus. Our protocol combines pulsed dynamic nuclear polarization, a phase-controlled radiofrequency pulse, and a multipulse AC sensing sequence with a modified readout pulse. Using a single nitrogen-vacancy center as a solid-state quantum sensor, we experimentally demonstrate this protocol on a single 13C nuclear spin in diamond and uniquely determine the lattice site of the target nucleus. Our result paves the way for magnetic resonance imaging at the single-molecular level., 21 pages, 15 figures, updated Ref. [39] (J. Zopes et al. arXiv:1806.04883)

Purpose The purpose of this study is to demonstrate quantitatively the complementary relationship between the introduction of intensity modulated radiation therapy (IMRT) and planning target volume (PTV) margin reduction with an image guided technique in reducing the risk of rectal toxicity in dose-escalating prostate radiation therapy. Methods and Materials Three-dimensional conformal radiation therapy (CRT) and IMRT plans were generated for 10 patients with prostate cancer based on 2 PTV margin protocols (10/8 mm and 6/5 mm) and 2 dose prescriptions (70 Gy and 78 Gy). The normal tissue complication probability (NTCP) for each of the 8 scenarios was calculated using the Lyman-Kutcher-Burman model to estimate the risk of rectal and bladder late toxicity. The conformity and homogeneity indices of PTVs were calculated for each plan. Results The IMRT plans showed superiority in conformity and inferiority in homogeneity over 3-dimensional CRT plans. The rectal NTCPs were increased 3.5 to 4.1 times when the prescribed total dose was changed from 70 Gy to 78 Gy and the dose delivery and the image guided radiation therapy techniques remained unchanged. PTV margin reduction was shown to reduce the value of rectal NTCP significantly. Overall, implementing the IMRT technique alone could reduce the NTCP values only by 2.1% to 7.3% from those of 3-dimensional CRT. The introduction of both IMRT and PTV margin reduction was found to be necessary for rectal NTCP to remain Conclusions The complementary relationship between the introduction of IMRT and PTV margin reduction was proven. We found that both approaches need to be implemented to safely deliver a curative dose in dose-escalating prostate radiation therapy.

Objective Recent data indicated that concurrent chemoradiotherapy (CCRT) using high dose cisplatin (CDDP) is the most useful treatment for advanced head and neck squamous cell carcinoma (SCC). Regarding the dose of CDDP, 100 mg/m2 is most recommended in Western countries. However, in terms of a balance of efficacy and adverse events, appropriate dose of cytotoxic drugs such as CDDP may be different among the different ethnic groups. In this multicenter phase I/II study, we aimed to identify the optimal dose of CDDP in CCRT for patients with advanced head and neck SCC in the Japanese. Methods Patients were eligible for inclusion if they had head and neck SCC that was treated with radical CCRT comprising whole-neck irradiation of the primary lesion and level II–IV lymph nodes on both sides. For the phase I study, a CDDP dose was 70 mg/m2 for level 0, 80 mg/m2 for level 1, and 100 mg/m2 for level 2. Maximum tolerated dose (MTD) and dose-limiting toxicity (DLT) were examined by phase I trial, by which CDDP dose for phase II was determined. The primary endpoint for the phase II was CCRT completion rate, and the secondary endpoint was full-dose-CCRT completion rate, the percentage of patients receiving a total CDDP dose of ≥200 mg/m2, response rate, and incidences of adverse events. Results A CDDP dose of 100 mg/m2 was the MTD for phase I, and the recommended dose for phase II was 80 mg/m2. Forty-seven patients were evaluated in the phase II trial. CCRT completion rate, full-dose-CCRT rate, and the percentage of patients receiving a total CDDP dose of ≥200 mg/m2, were 93.6%, 78.7%, and 93.6%, respectively. One patient (2.1%) developed grade 2 renal dysfunction, and no patient developed febrile neutropenia or a grade 4 adverse event. Conclusion The present phase I study indicated that a CDDP dose of 80 mg/m2 is the optimal dose in terms of safety. The phase II study revealed that CCRT completion rate, response rate, and rates of adverse events were not inferior for a CDDP dose of 80 mg/m2 as compared with a dose of 100 mg/m2, and a dose of 80 mg/m2 is therefore recommended in CCRT for the Japanese. This study was registered with the University Hospital Medical Information Network Clinical Trials Registry (UMIN-CTR; identification No. UMIN000010369).

To determine the current practice of stereotactic irradiation (STI) for brain metastases in Japan by a questionnaire survey. A questionnaire was distributed to 313 institutions performing STI with one of the following machines: Gamma Knife (GK), CyberKnife (CK), Novalis (Nov), or other linear accelerator (LINAC)-based systems (OLS). The participation was voluntary. There were 163 responding institutions. The total number of STI treatments between April 2013 and March 2014 was 10,684. Stereotactic radiosurgery (SRS) and fractionated stereotactic radiotherapy (SRT) were performed in 8624 (80.7%) and 2060 (19.3%) cases, respectively. Whole-brain radiation therapy (WBRT) was performed for a total of 3515 cases. For a case model of a 1.5-cm solitary brain metastasis in a non-eloquent area, the most common GTV-PTV margin was 2 mm (22 of 114 institutions), and an institutional standard fraction was 1 (75 of 114 institutions). The doses for the model case also varied from 13.0 to 26.0 Gy (Median 20 Gy) when converted to SRS (α/β = 10). A prescription point was at the PTV margin the most. The median dose constraints which were converted to SRS (α/β = 3) to organs at risk were 12.2, 12.7, and 13.7 Gy for optic nerves, cavernous sinus, and brainstem, respectively. STI for brain metastases in current practice varied significantly among institutions. These different strategies relied mostly on the type of treatment machine used. It is thus necessary to establish a common guideline to express dose prescriptions and plan qualities for different STI machines.

This tutorial article provides a concise and pedagogical overview on negatively-charged nitrogen-vacancy (NV) centers in diamond. The research on the NV centers has attracted enormous attention for its application to quantum sensing, encompassing the areas of not only physics and applied physics but also chemistry, biology and life sciences. Nonetheless, its key technical aspects can be understood from the viewpoint of magnetic resonance. We focus on three facets of this ever-expanding research field, to which our viewpoint is especially relevant: microwave engineering, materials science, and magnetometry. In explaining these aspects, we provide a technical basis and up-to-date technologies for the research on the NV centers., Comment: 16 pages, 15 figures. A tutorial article to appear in Journal of Applied Physics (Special Topic: Defects in Semiconductors 2017)

In this chapter, we discuss defects in silicon, primarily focusing on phosphorus donors, from the viewpoint of quantum information processing. We start with a historical perspective on our understanding of the limits to information processing. In doing so, we illuminate why we are so excited about the recent experimental challenges to realize silicon-based quantum computers. After reviewing the spin physics of donors in silicon, we discuss the coherence properties of donor electron and nuclear spins, and evaluate their feasibilities as carriers of quantum information, quantum bits. Recent developments in coherent control of single donor spins in silicon nanoelectronic devices are then outlined.

We report a rare case of intratumoral hemorrhage during postoperative radiotherapy for pituitary adenoma. A 57-year-old Asian male, complaining of long-standing eye strain, underwent a medical checkup of the brain. Magnetic resonance imaging showed a multicystic giant pituitary adenoma. The patient underwent an endoscopic endonasal transsphenoidal partial removal of the adenoma to provide optic pathway decompression and got relief from the visual symptoms. Just before completion of the postoperative radiotherapy for residual adenoma, the patient developed right hemiparesis, mild motor aphasia, and right oculomotor palsy. A cranial CT scan showed intratumoral hemorrhage into the intratumoral cyst. The patient therefore had to undergo three additional craniotomies for evacuation of cyst contents over the next 8 months. The follow-up MRI at 11 months after the initial hemorrhage showed that the new oozing of blood in the intratumoral cyst was still appearing. Intratumoral hemorrhage is a rare, albeit life-threatening, complication of pituitary adenoma. We reviewed relevant literature and suggested that the cystic component in pituitary adenoma could be a key pathogenesis of this rare complication. In conclusion, we suggest that it may be necessary to realize that cases which have cystic giant pituitary adenoma may cause hemorrhage by chance with the foreseeability.

To investigate the effects of a respiratory gating and multifield technique on the dose-volume histogram (DVH) in radiotherapy for esophageal cancer. Twenty patients who underwent four-dimensional computed tomography for esophageal cancer were included. We retrospectively created the four treatment plans for each patient, with or without the respiratory gating and multifield technique: No gating-2-field, No gating-4-field, Gating-2-field, and Gating-4-field plans. We compared the DVH parameters of the lung and heart in the No gating-2-field plan with the other three plans. In the comparison of the parameters in the No gating-2-field plan, there are significant differences in the Lung V5Gy, V20Gy, mean dose with all three plans and the Heart V25Gy–V40Gy with Gating-2-field plan, V35Gy, V40Gy, mean dose with No Gating-4-field plan and V30Gy–V40Gy, and mean dose with Gating-4-field plan. The lung parameters were smaller in the Gating-2-field plan and larger in the No gating-4-field and Gating-4-field plans. The heart parameters were all larger in the No gating-2-field plan. The lung parameters were reduced by the respiratory gating technique and increased by the multifield technique. The heart parameters were reduced by both techniques. It is important to select the optimal technique according to the risk of complications.

The changes in dose distribution caused by backscatter radiation from a common commercial dental alloy (Au–Ag–Pd dental alloy; DA) were investigated to identify the optimal material and thicknesses of a dental device (DD) for effective prevention of mucositis. To this end, 1 cm3 of DA was irradiated with a 6-MV X-ray beam (100 MU) in a field size of 10 × 10 cm2 using a Novalis TX linear accelerator. Ethylene vinyl acetate copolymer, polyolefin elastomer, and polyethylene terephthalate (PET) were selected as DD materials. The depth dose along the central axis was determined with respect to the presence/absence of DA and DDs at thicknesses of 1–10 mm using a parallel-plate ionization chamber. The dose in the absence of DDs showed the lowest value at a distance of 5 mm from the DA surface and gradually increased with distance between the measurement point and the DA surface for distances of ≥5 mm. Except for PET, no significant difference between the DA dose curves for the presence and absence of DDs was observed. In the dose curve, PET showed a slightly higher dose for DA with DD than for DA without DD for thicknesses of ≥4 mm. The findings herein suggest that the optimal DD material for preventing local dose enhancement of the mucosa caused by DA backscatter radiation should have a relatively low atomic number and physical density and that optimal DD thickness should be chosen considering backscatter radiation and percentage depth dose.

To retrospectively investigate the risk factors and time to occurrence of genitourinary (GU) toxicity after radiotherapy for localized prostate cancer.The study included 320 patients. The radiotherapy planning target volume encompassed the prostate with a 1-cm margin in the transverse plane and a 1-cm margin (Group A) or a 1.5-cm margin (Group B) in the longitudinal plane. Incidence rates, risk factors and time to occurrence of GU toxicity were evaluated.After a median follow-up of 38.2 months, the rate of late grade 2-3 GU toxicity was 5.9% and the median interval was 18.3 months. The wider longitudinal margin was the single significant independent factor. The 2-year cumulative incidence rates of late grade ≥2 GU toxicity were 2.8% and 7.5% in Group A and B patients.A wider radiotherapy margin increased the risk of GU toxicity and led to earlier occurrence.

Long-distance quantum teleportation and quantum repeater technologies require entanglement between a single matter quantum bit (qubit) and a telecommunications (telecom)-wavelength photonic qubit. Electron spins in III-V semiconductor quantum dots are among the matter qubits that allow for the fastest spin manipulation and photon emission, but entanglement between a single quantum-dot spin qubit and a flying (propagating) photonic qubit has yet to be demonstrated. Moreover, many quantum dots emit single photons at visible to near-infrared wavelengths, where silica fibre losses are so high that long-distance quantum communication protocols become difficult to implement. Here we demonstrate entanglement between an InAs quantum-dot electron spin qubit and a photonic qubit, by frequency downconversion of a spontaneously emitted photon from a singly charged quantum dot to a wavelength of 1,560 nanometres. The use of sub-10-picosecond pulses at a wavelength of 2.2 micrometres in the frequency downconversion process provides the necessary quantum erasure to eliminate which-path information in the photon energy. Together with previously demonstrated indistinguishable single-photon emission at high repetition rates, the present technique advances the III-V semiconductor quantum-dot spin system as a promising platform for long-distance quantum communication.

Purpose The purpose of this study was to elucidate the efficacy and optimal method of radiotherapy in the management of solitary extramedullary plasmacytoma occurring in the head and neck regions (EMPHN). Methods and Materials Sixty-seven patients (43 male and 24 female) diagnosed with EMPHN between 1983 and 2008 at 23 Japanese institutions were reviewed. The median patient age was 64 years (range, 12–83). The median dose administered was 50 Gy (range, 30–64 Gy). Survival data were calculated by the Kaplan-Meier method. Results The median follow-up duration was 63 months. Major tumor sites were nasal or paranasal cavities in 36 (54%) patients, oropharynx or nasopharynx in 16 (23%) patients, orbita in 6 (9%) patients, and larynx in 3 (5%) patients. The 5- and 10-year local control rates were 95% and 87%, whereas the 5- and 10-year disease-free survival rates were 56% and 54%, respectively. There were 5 (7.5%), 12 (18%), and 8 (12%) patients who experienced local failure, distant metastasis, and progression to multiple myeloma, respectively. In total, 18 patients died, including 10 (15%) patients who died due to complications from EMPHN. The 5- and 10-year overall survival (OS) rates were 73% and 56%, respectively. Radiotherapy combined with surgery was identified as the lone significant prognostic factor for OS (p = 0.04), whereas age, gender, radiation dose, tumor size, and chemotherapy were not predictive. No patient experienced any severe acute morbidity. Conclusions Radiotherapy was quite effective and safe for patients with EMPHN. Radiotherapy combined with surgery produced a better outcome according to survival rates. These findings require confirmation by further studies with larger numbers of patients with EMPHN.

We demonstrate detection of spin polarization in a quantum wire utilizing a side coupled quantum dot. By applying in-plane magnetic fields, spin split conducting channels are formed and produce spin polarization in the wire. The magnetic fields also create Zeeman split spin levels in the dot and these states are used as a spin polarization detector. Such kind of spin polarization detection with a side coupled quantum dot will operate even in the zero magnetic field by using two-electron singlet and triplet levels.

We report the case of a 51-year-old woman who showed elevation of serum carcinoembryonic antigen (CEA) level 14 months after chemoradiation therapy for her cervical esophageal cancer. Close examination demonstrated that the patient was suffering from hypothyroidism probably due to the chemoradiation therapy. The serum CEA level decreased after starting supplementary treatment with oral levothyroxine. The exact mechanism underlying the elevated level of CEA observed in a patient with hypothyroidism is unclear. However, we should be aware of the possibility of transient elevation of CEA affected by thyroid function in patients after radiation therapy for head and neck cancer.

We report a study of the Aharonov–Bohm (AB) type oscillation of weak field magnetoresistance in an anti-dot lattice (ADL) of a two-dimensional hole system in the presence of strong spin–orbit interaction. The Fourier transform of the oscillations reveals non-monotonic evolutions with the different range of harmonic component, which are indicative of the existence of additional phase factors. A simulation considering Berry’s phase and the phase arising from the spin–orbit shift in the momentum space shows qualitative agreement with the experiment.

We report on a microwave planar ring antenna specifically designed for optically-detected magnetic resonance (ODMR) of nitrogen-vacancy (NV) centers in diamond. It has the resonance frequency at around 2.87 GHz with the bandwidth of 400 MHz, ensuring that ODMR can be observed under external magnetic fields up to 100 G without the need of adjustment of the resonance frequency. It is also spatially uniform within the 1-mm-diameter center hole, enabling the magnetic-field imaging in the wide spatial range. These features facilitate the experiments on quantum sensing and imaging using NV centers at room temperature., Comment: 6 pages, 6 figures, to appear in Review of Scientific Instruments

Pharaonis phoborhodopsin (ppR), also called pharaonis sensory rhodopsin II, NpSRII, is a photoreceptor for the photophobic response of Natronomonas pharaonis. Tryptophan 182 (W182) of bacteriorhodopsin (bR) is near the chromophore retinal and has been suggested to interact with retinal during the photoreaction and also to be involved in the hydrogen-bonding network around the retinal. W182 of bR is conserved in ppR as tryptophan 171 (W171). To elucidate whether W171 of ppR interacts with retinal during the photoreaction and/or is involved in the hydrogen-bonding network as in bR, we formed W171-substituted mutants of ppR, W171A and W171T. Our low-temperature spectroscopic study has revealed that the substitution of W171 to Ala or Thr resulted in the stabilization of M- and O-intermediates. The stability of M and absorption spectral changes during the M-decay were different depending on the substituted residue. These findings suggest that W171 in ppR interacts with retinal and the degree of the interaction depends on the substituted residues, which might be rate determining in the M-decay. In addition, the involvement of W171 in the hydrogen-bonding network is suggested by the O-decay. We also found that glycerol slowed the decay of M and not of O.

We evaluated the efficacy and toxicity of radiation combined with daily, low-dose protracted chemotherapy for locally advanced esophageal cancer.We analyzed data for 68 patients with locally advanced esophageal cancer, including 18 surgical candidates. Standard fractionation (total dose range, 60 to 70 Gy) was used for radiotherapy. The chemotherapy consisted of a daily 5-fluorouracil dose of 250 mg/m2, with a cis-diammine-dichloro-platinum dose of 3 mg/m2 administered on radiotherapy days.Sixty-four patients (94%) received at least 60 Gy. Grade 3 acute hematological toxicity was observed in 13 (19%) patients; there was no grade 4 hematological toxicity. Complete response, partial response, no change, and progressive disease were obtained in 22, 35, 7, and 4 patients, respectively. Minimum follow-up for surviving patients was 45 months. Locoregional progression-free rates at 3 and 5 years were 47% and 47%. Four patients died of late cardiac toxicity; the primary site for all 4 patients was the middle thoracic esophagus. Overall survival rates at 2, 3, and 5 years were 40%, 32%, and 20%. The 3- and 5-year survival rates in patients with T2-3M0 disease were 43% and 27%, and the rates were 24% and 15% in patients with T4/M1.Given the large proportion of patients in this study with inoperable disease (roughly three quarters), our treatment seemed to provide equivalent efficacy and less hematological toxicity than standard-dose chemoradiotherapy.

Practical quantum communication between remote quantum memories rely on single photons at telecom wavelengths. Although spin-photon entanglement has been demonstrated in atomic and solid-state qubit systems, the produced single photons at short wavelengths and with polarization encoding are not suitable for long-distance communication, because they suffer from high propagation loss and depolarization in optical fibres. Establishing entanglement between remote quantum nodes would further require the photons generated from separate nodes to be indistinguishable. Here, we report the observation of correlations between a quantum-dot spin and a telecom single photon across a 2-km fibre channel based on time-bin encoding and background-free frequency downconversion. The downconverted photon at telecom wavelengths exhibits two-photon interference with another photon from an independent source, achieving a mean wavepacket overlap of greater than 0.89 despite their original wavelength mismatch (900 and 911 nm). The quantum-networking operations that we demonstrate will enable practical communication between solid-state spin qubits across long distances., Quantum communication requires quantum correlations between the information processing units and the information carrying units. Here, the authors use time-bin encoding and frequency downconversion to telecom wavelengths to achieve kilometre-scale spin-photon correlations.

Pancreatic neuroendocrine tumors (pNETs) are an uncommon malignancy arising from the neuroendocrine cells of pancreas. Most cases of pNETs present with metastatic disease, but there are few reports in the literature describing pNETs metastasis to the lung and mediastinal lymph nodes [1]. Moreover, although a multimodal treatment including surgical resection and chemotherapy is acceptable for management of pNETs, advanced pNETs still remain a difficult therapeutic challenge [2, 3]. Radiotherapy or combined chemoradiotherapy has not been standard in the treatment of pNETs. An 80-year-old female was admitted to our hospital with cough and anorexia. She had been diagnosed and resected pNETs 8 years ago. Mass shadow was pointed out with chest X-ray, and endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) was performed. Pathological examination revealed neuroendocrine tumors, so the lung mass was considered as metastasis of pNETs. Then, we discussed her treatment at Cancer Board, and radiotherapy was chosen. We hope this case suggests that radiotherapy will be one of the treatment options for metastatic pNETs.

We investigate spin coherence time of electrons bound to phosphorus donors in silicon single crystals. The samples are isotopically controlled so that they may possess various concentrations (from 4.7% to 99.2%) of 29 Si, which is the only non-zero-spin stable isotope of silicon. The orientation dependence of electron-spin coherence times are presented, and electron spin echo envelope modulation is analyzed in time-frequency space.

We investigate spin coherence time of electrons bound to phosphorus donors in silicon single crystals, employing a pulsed electron paramagnetic resonance technique. The samples were isotopically controlled so that they may possess different concentrations (about 5% and 100%) of 29Si, which is the only non-zero-spin (spin-1/2) stable isotope of Si. Both 29Si-concentration dependence and orientation dependence of the electron spin coherence time demonstrate that the decoherence is caused by spectral diffusion due to mutual flip-flops of the environmental nuclear spins. The detail analysis of spin echo decay curves enables the unique assignment of the host sites responsible for electron spin echo envelope modulation.

A solid-state quantum computer composed entirely of semiconductor silicon is proposed. Qubits are nuclear spins, I = 1/2, of 29Si stable isotopes in the form of atomic chains embedded in a nuclear-spin free matrix of 28Si stable isotopes. Each 29Si nuclear spin in a chain can be accessed selectively with a different resonant frequency (rf) due to a large magnetic field gradient created by a nearby micromagnet, i.e., unitary operations needed for quantum computing can be performed by fine tuning of the rf. Ensemble readout of qubits from 105 copies of the atomic chain is accomplished by magnetic resonance force microscopy.

We report on an ion implantation technique utilizing a screening mask made of SiO$_2$ to control both the depth profile and the dose. By appropriately selecting the thickness of the screening layer, this method fully suppresses the ion channeling, brings the location of the highest NV density to the surface, and effectively reduces the dose by more than three orders of magnitude. With a standard ion implantation system operating at the energy of 10 keV and the dose of 10$^{11}$ cm$^2$ and without an additional etching process, we create single NV centers close to the surface with coherence times of a few tens of $\mu$s., Comment: 5 pages, 4 figures

We perform pulsed optically detected electron spin resonance to measure the DC magnetic field sensitivity and electronic spin coherence time T_2 of an ensemble of near-surface, high-density nitrogen-vacancy (NV) centers engineered to have a narrow magnetic resonance linewidth. Combining pulsed spectroscopy with dynamic nuclear polarization, we obtain the photon-shot-noise-limited DC magnetic sensitivity of 35 nT Hz^{-0.5}. We find that T_2 is controlled by instantaneous diffusion, enabling decoherence spectroscopy on residual nitrogen impurity spins in the diamond lattice and a quantitative determination of their density. The demonstrated high DC magnetic sensitivity and decoherence spectroscopy are expected to broaden the application range for two-dimensional magnetic imaging.

The effects of host isotope mass on the hyperfine interaction of group-V donors in silicon are revealed by pulsed electron nuclear double resonance (ENDOR) spectroscopy of isotopically engineered Si single crystals. Each of the hyperfine-split P-31, As-75, Sb-121, Sb-123, and Bi-209 ENDOR lines splits further into multiple components, whose relative intensities accurately match the statistical likelihood of the nine possible average Si masses in the four nearest-neighbor sites due to random occupation by the three stable isotopes Si-28, Si-29, and Si-30. Further investigation with P-31 donors shows that the resolved ENDOR components shift linearly with the bulk-averaged Si mass., 5 pages, 4 figures, 1 table

We have confirmed band warping effect of twodimensional holes confined at GaAs/AlGaAs singleheterojunction through classical commensurability resistance oscillations in anti-dot lattices (ADLs). The oscillations in the triangular ADLs are decomposed into three peaks, two of which are assigned to localized orbits of holes with a lighter effective math (l-hole), and the other is assigned to that of holes with heavier average effective math (h-hole). The latter assignment is possible only when the h-hole band is heavily warped, thus evidencing the warping. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

We study the low-field magnetotransport of a twodimensional hole antidot lattice subject to strong spinorbit interaction. The Aharonov-Bohm type oscillations appearing in the low-temperature magnetoresistance have components corresponding to h /e and h /2e. We interpret the nodes seen in the h /e oscillations as signatures of the spin-orbit Berry phase, based on a simple simulation taking into account its contribution. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

We report the control of the orbital occupation by using the intra-orbital Coulomb interaction in quantum dots Tcoupled to quantum wires. With the change of the confinement potential, intra-orbital Coulomb interaction exceeds orbital level spacing and influences the orbital occupation. We realize such potential modification by changing either the gate design or the voltages applied to the gates. The rearrangement of the orbital occupation is confirmed from the response of the addition energy spectroscopy to the magnetic field. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

We present experiments on electronic states in few-electron lateral quantum dots side-coupled to quantum wires. The side-coupled structure enabled us to prepare the dots with various spatial sizes. The Coulomb energy and the quantum confinement energy depend on the dot size in different ways and thus the change in the size causes the change in the relative amplitude of the two energy scales. This results in non-monotonic occupation of single-electron energy levels. We have observed such non-trivial occupation through the collapse of the magic numbers and the response to magnetic field.

Purpose: To assess an accuracy of fiducial maker-based setup using ExacTrac (ExT-based setup) as compared with soft tissue-based setup using Cone-beam CT (CBCT-based setup) for patients with prostate cancer receiving intensity-modulated radiation therapy (IMRT) for the purpose of investigating whether ExT-based setup can be an alternative to CBCT-based setup. Methods: The setup accuracy was analyzed prospectively for 7 prostate cancer patients with implanted three fiducial markers received IMRT. All patients were treated after CBCT-based setup was performed and corresponding shifts were recorded. ExacTrac images were obtained before and after CBCT-based setup. The fiducial marker-based shifts were calculated based on those two images and recorded on the assumption that the setup correction was carried out by fiducial marker-based auto correction. Mean and standard deviation of absolute differences and the correlation between CBCT and ExT shifts were estimated. Results: A total of 178 image dataset were analyzed. On the differences between CBCT and ExT shifts, 133 (75%) of 178 image dataset resulted in smaller differences than 3 mm in all dimensions. Mean differences in the anterior-posterior (AP), superior-inferior (SI), and left-right (LR) dimensions were 1.8 ± 1.9 mm, 0.7 ± 1.9 mm, and 0.6 ± 0.8 mm, respectively. The percentages of shiftmore » agreements within ±3 mm were 76% for AP, 90% for SI, and 100% for LR. The Pearson coefficient of correlation for CBCT and ExT shifts were 0.80 for AP, 0.80 for SI, and 0.65 for LR. Conclusion: This work showed that the accuracy of ExT-based setup was correlated with that of CBCT-based setup, implying that ExT-based setup has a potential ability to be an alternative to CBCT-based setup. The further work is to specify the conditions that ExT-based setup can provide the accuracy comparable to CBCT-based setup.« less

Semiconductor quantum dots can be utilized to capture single electron or hole spins and they have therewith promise for various applications in fields like spintronics, spin based quantum information processing and chiral photonics. We integrate quantum dots into semiconductor microcavities to enhance light-matter interaction for ultrafast optical manipulation and read-out. Single electron and single hole spins can be statistically or deterministically loaded into the quantum dots and coherently controlled. Within the about μs-coherence times of the spins about 105 complete single qubit rotations can be performed with ultrafast optical pulses. By utilizing a Λ-type energy level system of a single quantum-dot electron spin in a magnetic field and ultrafast non-linear frequency conversion, quantum-dot spin-photon entanglement is observed.

The aim of our study was to analyze changes over time in the characteristics, treatment, and outcome of patients with primary central nervous system lymphoma (PCNSL). Data on 315 patients with histologically proven PCNSL undergoing radiotherapy between 2005 and 2009 were collected from 20 Japanese institutions using a questionnaire. These data were then compared with data on 273 patients treated during the period 1995–2004 and those on 466 patients treated during the period 1985–1994. In terms of patient and tumor characteristics, we found a significant increase in mean patient age in the 2005–2009 period compared to the 1985–2004 period (63 vs. 58–59 years, respectively) and in the percentage of patients with better performance status (PS) during the 2005–2009 period compared with the 1995–2004 period (World Health Organization PS 0–2: 73 vs. 65 %, respectively). Regarding treatment, relative to the 1995–2004 period, significant changes in the 2005–2009 period were (1) decreased rate of attempting tumor resection (23 vs. 44 %); (2) increased use of chemotherapy (78 vs. 68 %), and (3) increased use of methotrexate (MTX)-containing regimens (84 vs. 53 %). The 5-year overall survival rates were 15.3, 30.1, and 36.5 % for patients seen during the 1985–1994, 1995–2004, and 2005–2009 periods, respectively, but relapse-free survival did not improve between the 1995–2004 and 2005–2009 periods (26.7 vs. 25.7 % at 5 years, respectively). Patients receiving MTX-containing chemotherapy had 5-year survival rates of 19, 50, and 44 % during these three periods, respectively. Although patient backgrounds differed among the study periods, recent trends were a high patient age, better PS, avoidance of extensive tumor resection, more frequent use of chemotherapy, and improved survival. The recent improvement in survival may be due to improvements in second-line treatment and supportive care.