Power Spectrum of Light Scattered by Three-Level Systems

The power spectrum of the light scattered by a three-level atom driven near resonance between the ground state (|1>) and the second excited state (|3>) by a monochromatic classical electric field is evaluated following the method developed by B. R. Mollow. The incident field is assumed to interact with the dipole moment between the states |1> and |3>, while the emitted light is assumed to interact with that between the state |3> and the first excited state |2> of the atom. The atom is assumed to relax to equilibrium only via radiation damping for the sake of simplicity. The power spectrum of the scattered field is explicitly calculated from the two-time atomic dipole moment correlation function, which is evaluated on a Markoff-type assumption, and various limiting cases are discussed. In Appendix the case is considered in which radiative damping between the higher excited state and the ground state is also present.Article信州大学理学部紀要 21(2): 89-104(1987)departmental bulletin pape

Adversarially Trained Object Detector for Unsupervised Domain Adaptation

Unsupervised domain adaptation, which involves transferring knowledge from a label-rich source domain to an unlabeled target domain, can be used to substantially reduce annotation costs in the field of object detection. In this study, we demonstrate that adversarial training in the source domain can be employed as a new approach for unsupervised domain adaptation. Specifically, we establish that adversarially trained detectors achieve improved detection performance in target domains that are significantly shifted from source domains. This phenomenon is attributed to the fact that adversarially trained detectors can be used to extract robust features that are in alignment with human perception and worth transferring across domains while discarding domain-specific non-robust features. In addition, we propose a method that combines adversarial training and feature alignment to ensure the improved alignment of robust features with the target domain. We conduct experiments on four benchmark datasets and confirm the effectiveness of our proposed approach on large domain shifts from real to artistic images. Compared to the baseline models, the adversarially trained detectors improve the mean average precision by up to 7.7%, and further by up to 11.8% when feature alignments are incorporated. Although our method degrades performance for small domain shifts, quantification of the domain shift based on the Frechet distance allows us to determine whether adversarial training should be conducted.Comment: 10 pages, 6 figures. This work has been submitted to the IEEE for possible publication. Copyright may be transferred without notice, after which this version may no longer be accessibl

A Case of High-Grade Glioma in an Eloquent Area Treated with Awake Craniotomy in an 85-year-old Patient

An 85-year-old woman presented with aphasia due to an occupying lesion in the left frontal lobe near the language area. Complete resection of the contrast-enhancing lesion was performed under awake conditions. The pathological diagnosis was anaplastic astrocytoma, and postoperative radiochemotherapy was administered. Awake surgery is a useful technique to reduce postoperative neurological sequelae and to maximize surgical resection. Although the patient was elderly, which is generally considered high risk, she did not have any severe neurological deficits and had a good outcome. Even in the extreme elderly, awake surgery can be useful for gliomas in language cortices

Neurosurgery for brain metastasis from breast cancer

Breast cancer is the most common malignancy among women worldwide, and the main cause of death in patients with breast cancer is metastasis. Metastasis to the central nervous system occurs in 10% to 16% of patients with metastatic breast cancer, and this rate has increased because of recent advancements in systemic chemotherapy. Because of the various treatments available for brain metastasis, accurate diagnosis and evaluation for treatment are important. Magnetic resonance imaging (MRI) is one of the most reliable preoperative examinations not only for diagnosis of metastatic brain tumors but also for estimation of the molecular characteristics of the tumor based on radiographic information such as the number of lesions, solid or ring enhancement, and cyst formation. Surgical resection continues to play an important role in patients with a limited number of brain metastases and a relatively good performance status. A single brain metastasis is a good indication for surgical treatment followed by radiation therapy to obtain longer survival. Surgical removal is also considered for two or more lesions if neurological symptoms are caused by brain lesions of >3 cm with a mass effect or associated hydrocephalus. Although maximal safe resection with minimal morbidity is ideal in the surgical treatment of brain tumors, supramarginal resection can be achieved in select cases. With respect to the resection technique, en bloc resection is generally recommended to avoid leptomeningeal dissemination induced by piecemeal resection. An operating microscope, neuronavigation, and intraoperative neurophysiological monitoring are essential in modern neurosurgical procedures, including tumor resection. More recently, supporting surgical instruments have been introduced. The use of endoscopic surgery has dramatically increased, especially for intraventricular lesions and in transsphenoidal surgery. An exoscope helps neurosurgeons to comfortably operate regardless of patient positioning or anatomy. A tubular retractor can prevent damage to the surrounding brain tissue during surgery and is a useful instrument in combination with both an endoscope and exoscope. Additionally, 5-aminolevulinic acid (5-ALA) is a promising reagent for photodynamic detection of residual tumor tissue. In the near future, novel treatment options such as high-intensity focused ultrasound (HIFU), laser interstitial thermal therapy (LITT), oncolytic virus therapy, and gene therapy will be introduced

High Signal Intensity of the Cochlear Modiolus on Unenhanced T1-Weighted Images in Classical Infratentorial Superficial Siderosis

Background: Superficial siderosis (SS) results from chronic bleeding in the subarachnoid space. SS can be classified as infratentorial SS (i-SS) and supratentorial SS (s-SS). The cochlear modiolus (CM) normally shows low signal intensity (SI) on Tl-weighted images (T1WI). We noticed persistently high SI of the CM on unenhanced thin-sliced T1WI in patients with i-SS. The purpose of this study was to evaluate the correlation between SS and high SI of the CM on unenhanced T1WI. Methods: This retrospective study analyzed three cases with i-SS, eight cases with s-SS, and 23 normal controls (NC) evaluated on unenhanced thin-sliced T1WI with a three-dimensional spoiled gradient-recalled echo sequence. CM-T1SI scores of 0, 1, and 2 indicated low, iso, and high SI, respectively. In cases with scores of 2 evaluated several times, all scores were reviewed for each case. The CM-T1SI ratio was defined as the contrast ratio between the CM and the cerebellum. Differences between the three groups were statistically analyzed based on the CM-T1SI score and ratio. Receiver operative curve (ROC) analysis was used to determine the cut-off values for differentiating the i-SS group from the NC group based on the CM-T1SI ratio. Results: Two patients with i-SS had a score of 2 on all evaluations. The CM-T1SI score and ratio differed significantly between the i-SS and NC groups. The accuracy of the CM-T1SI ratio for discriminating i-SS from NC was 98.9% at a cutoff value of 0.628. Conclusion: High SI of the CM on unenhanced TIWI can be an additional characteristic finding of i-SS

Integrin Inhibitor Suppresses Bevacizumab-Induced Glioma Invasion

Glioblastoma is known to secrete high levels of vascular endothelial growth factor (VEGF), and clinical studies with bevacizumab, a monoclonal antibody to VEGF, have demonstrated convincing therapeutic benefits in glioblastoma patients. However, its induction of invasive proliferation has also been reported. We examined the effects of treatment with cilengitide, an integrin inhibitor, on bevacizumab-induced invasive changes in glioma. U87 Delta EGFR cells were stereotactically injected into the brain of nude mice or rats. Five days after tumor implantation, cilengitide and bevacizumab were administered intraperitoneally three times a week. At 18 days after tumor implantation, the brains were removed and observed histopathologically. Next, the bevacizumab and cilengitide combination group was compared to the bevacizumab monotherapy group using microarray analysis. Bevacizumab treatment led to increased cell invasion in spite of decreased angiogenesis. When the rats were treated with a combination of bevacizumab and cilengitide, the depth of tumor invasion was significantly less than with only bevacizumab. Pathway analysis demonstrated the inhibition of invasion-associated genes such as the integrin-mediated cell adhesion pathway in the combination group. This study showed that the combination of bevacizumab with cilengitide exerted its anti-invasive effect. The elucidation of this mechanism might contribute to the treatment of bevacizumab-refractory glioma

Neonatal Intrathymic Splenocyte Injection Yields Prolonged Cardiac Xenograft Survival

Intrathymic (i.t.) injection of allogenic cells without administration of anti-lymphocyte serum (ALS) in neonatal recipients has induced donor-specific tolerance to subsequent cardiac allografts in rats. This study examines whether similar tactics can be successfully applied to a hamster-to-rat cardiac xenotransplantation model. Lewis neonates on their first day of life underwent i.t., subcutaneous (s.c.), intraperitoneal (i.p.), or intravenous (i.v.) injections of 5 x 10(7) Golden Syrian hamster splenocytes. After six weeks, the rats underwent heterotopic cardiac transplantation of hamster hearts. Cyclophosphamide (CyP) was administered on the day before surgery and postoperatively to suppress antibody-mediated graft rejection. Rats given splenocytes with 80 mg/kg of CyP had the following graft survival times: 8 to 12 days for i.t. injection (mean, 9.4 days); 5 to 7 days for s.c. injection (mean, 6.6 days); 4 to 11 days for i.p. injection (mean, 7.4 days); and 4 to 13 days for i.v. injection (mean, 7.9 days). Only the extension of graft survival produced by i.t. injection was statistically significant in comparison with the rats given only CyP treatment (mean, 7.5 days; P &#60; 0.05). Thus, it appears that i.t. injection of xenogenic splenocytes in neonatal recipients with administration of CyP, but without ALS, can prolong xenograft survival. This biological intervention may be most useful in pediatric xenotransplantation when combined with other immunomodulation techniques.</p

Study of Complete Genome Sequences of Rotavirus A Epidemics and Evolution in Japan in 2012–2014

A comprehensive molecular epidemiological study using next-generation sequencing technology was conducted on 333 rotavirus A (RVA)-positive specimens collected from six sentinel hospitals across Japan over three consecutive seasons (2012–2014). The majority of the RVA isolates were grouped into five genotype constellations: Wa-like G1P[8], DS-1-like G1P[8], G2P[4], G3P[8] and G9P[8]. Phylogenetic analysis showed that the distribution of strains varied by geographical locations and epidemic seasons. The VP7 genes of different G types were estimated to evolve at 7.26 × 10-4–1.04 × 10-3 nucleotide substitutions per site per year. The Bayesian time-scaled tree of VP7 showed that the time to the most recent common ancestor of epidemic strains within a region was 1–3 years, whereas that of the epidemic strains across the country was 2–6 years. This study provided, for the first time, the timeframe during which an epidemic strain spread locally and within the country and baseline information needed to predict how rapidly RVAs spread

Cavernous malformation of the optic chiasm with continuous hemorrhage in a pregnant woman: A case report

Background Cavernous malformation of the anterior visual pathway is rare, especially in pregnant woman. Planning a treatment strategy with cross-disciplinary specialists is important. Case description A 27-year-old pregnant woman presented with acute hemorrhage around the right optic nerve and chiasm, manifesting as poor vision in both eyes. Examination revealed right-eye deteriorated acuity and bilateral temporal hemianopsia. Computed tomography showed an oval high-density mass in the suprasellar region. Gradient echo-based T2-weighted magnetic resonance imaging showed the lesion to be hypointense (possibly a hematoma) and mainly in the optic chiasm. Fluid attenuated inversion recovery imaging showed a bilateral optic tract surrounding the lesion, which enlarged over 1 week, increasing the loss of visual function. Five days after admission, she delivered a healthy >2500-g baby by cesarean section (CS). Right frontotemporal craniotomy was performed 7 days after CS. Incision of the right optic nerve's lateral surface revealed clotted blood with abnormal vascular construction from the right side of the chiasm. We removed the hematoma and vascular lesion. Visual evoked potentials were detected only after optic chiasm decompression. Histological evaluation revealed a hematoma-like lesion with capsules and hemosiderin deposition, suggesting cavernous malformation. Her postoperative recovery was uneventful, with right visual acuity returning to normal, and her visual field not deteriorating any more. Conclusion Devising a treatment strategy with the obstetrician was important in this case to manage the hematoma and cavernous malformation safely