Circulating tumor-associated antigen-specific IFNγ+4-1BB+ CD8+ T cells as peripheral biomarkers of treatment outcomes in patients with pancreatic cancer

CD8+ T cells affect the outcomes of pancreatic ductal adenocarcinoma (PDAC). Using tissue samples at pre-treatment to monitor the immune response is challenging, while blood samples are beneficial in overcoming this limitation. In this study, we measured peripheral antigen-specific CD8+ T cell responses against four different tumor-associated antigens (TAAs) in PDAC using flow cytometry and investigated their relationships with clinical features. We analyzed the optimal timing within the treatment course for effective immune checkpoint inhibition in vitro. We demonstrated that the frequency of TAA-specific IFNγ+4-1BB+ CD8+ T cells was correlated with a fold reduction in CA19-9 before and after neoadjuvant therapy. Moreover, patients with TAA-specific IFNγ+4-1BB+ CD8+ T cells after surgery exhibited a significantly improved disease-free survival. Anti-PD-1 treatment in vitro increased the frequency of TAA-specific IFNγ+4-1BB+ CD8+ T cells before neoadjuvant therapy in patients, suggesting the importance of the timing of anti-PD-1 inhibition during the treatment regimen. Our results indicate that peripheral immunophenotyping, combined with highly sensitive identification of TAA-specific responses in vitro as well as detailed CD8+ T cell subset profiling via ex vivo analysis, may serve as peripheral biomarkers to predict treatment outcomes and therapeutic efficacy of immunotherapy plus neoadjuvant chemotherapy.

[A Case of Right Hemicolectomy for Inflammatory Myofibroblastic Tumor Arising in the Right Transverse Colon]

The patient was a 21-year-old male. He presented with right lower abdominal pain and showed tenderness in the same area. An abdominal contrast-enhanced CT examination revealed a 45 mm tumor that continuously stained in the right transverse colon. The patient presented with tenderness and rebound tenderness. Due to a suspected submucosal tumor, laparotomy was performed and an elastic hard tumor of 5 cm in size was found on the serous membrane side of the right transverse colon. As malignancy could not be ruled out, a right hemicolectomy with lymph node dissection was performed. The pathological diagnosis was an inflammatory myofibroblastic tumor(IMT), characterized by the proliferation of spindle- shaped spindle-shaped fibroblast-like cells with inflammatory cell infiltration. As of 9 years post-surgery, there has been no recurrence. However, long-term surveillance is necessary.

[Long-Term Survival of a Patient with Advanced Antral Gastric Cancer Successfully Treated with Multidisciplinary Therapy]

We report the case of long-term survival of a patient with advanced antral gastric cancer with multiple paraaortic lymph nodes metastasis who was successfully treated with multidisciplinary therapy. A 70-year-old female was admitted to our hospital complaining of vomiting. Upper gastrointestinal endoscopy revealed a Type 3 tumor in the gastric antrum. Computed tomography(CT)showed a marked decrease in the size of the primary gastric tumor and lymph nodes after 9 courses of mFOLFOX6 therapy. Subsequently, 7 courses of paclitaxel plus ramucirumab(PTX plus Rmab)therapy and 10 courses of nivolumab therapy were administered. After nivolumab therapy, marked shrinkage of the lymph nodes was observed on CT. Distal gastrectomy with D2(+ #16a2+b1)lymph node dissection was performed. The pathological finding was ypT0N1M0 with a Grade 3 effect of the chemotherapy. After 6 months of adjuvant chemotherapy with S-1, CT revealed supraclavicular lymph node metastases. After 4 courses of nivolumab therapy, CT showed a marked increase in the size of the lymph node. Consequently, the regimen was changed to irinotecan. After 16 courses of irinotecan therapy, CT showed a marked shrinkage in the size of the lymph node. The patient is currently alive with no signs of recurrence for 5 years, ie, since the initiation of the multidisciplinary therapy.

[An Experience of Multidisciplinary Treatment for Advanced Esophageal Cancer with Tumor Perforation during Preoperative Chemotherapy]

Perforation of esophageal cancer is one of the fatal oncologic emergencies, and a prompt and accurate treatment strategy is required. Here, we report a case of advanced esophageal cancer that had perforated during preoperative chemotherapy and was successfully resected with multidisciplinary treatment. The prognosis of perforated esophageal cancer can be expected to improve by multidisciplinary treatment appropriately combining initial treatment for infection control and subsequent cancer treatment.

[A Case of Surgery for Skin Metastasis of Papillary Thyroid Carcinoma in a Very Elderly Patient to Improve the Quality of Life]

The patient was a 100-year-old woman who underwent right lobe thyroidectomy for papillary thyroid cancer in another hospital around 1990. She developed local recurrence in 2010 and underwent anterior tracheal local recurrence resection in May 2017. Subsequently, metastases were confirmed in the lateral cervical lymph nodes, but the patient only received TSH suppression because of her advanced age. Multiple pulmonary metastases developed in November 2020 and supraclavicular lymph node metastases in July 2021, but the patient was under the care of a visiting physician on best supportive care. The patient was referred to our hospital in January 2022 due to the appearance of a cutaneous mass in the sternal incision area, which gradually increased in size. A well-mobile, well-defined, spherical mass was found in the sternotomy area. The maximum diameter was 19 mm. The cytological findings were consistent with cutaneous metastasis of papillary thyroid carcinoma. As the patient was elderly and had multiple pulmonary metastases, she was temporarily observed. However, by June 2022, the mass had increased from 19 mm to 33 mm with cutaneous discoloration. There was no tendency for multiple pulmonary metastases to grow during this period. The decision was made to operate in order to prevent a decline in quality of life due to self-destruction of the cutaneous metastasis. The tumor was removed under general anesthesia, including the cutaneous discoloration, and reconstructed with a rhomboid skin flap. Post-operatively, there was no local recurrence or significant increase in pulmonary metastases. It is suggested that resection of cutaneous metastasis of malignant tumors may be effective in preserving quality of life even in a 100-year-old elderly patient like the present case and should be considered as an indication.

Regnase-1 downregulation promotes pancreatic cancer through myeloid-derived suppressor cell-mediated evasion of anticancer immunity

BACKGROUND

Pancreatitis is known to be an important risk factor for pancreatic ductal adenocarcinoma (PDAC). However, the exact molecular mechanisms of how inflammation promotes PDAC are still not fully understood. Regnase-1, an endoribonuclease, regulates immune responses by degrading mRNAs of inflammation-related genes. Herein, we investigated the role of Regnase-1 in PDAC.

METHODS

Clinical significance of intratumor Regnase-1 expression was evaluated by immunohistochemistry in 39 surgically-resected PDAC patients. The functional role of Regnase-1 was investigated by pancreas-specific Regnase-1 knockout mice and Kras-mutant Regnase-1 knockout mice. The mechanistic studies with gene silencing, RNA immunoprecipitation sequencing (RIP-seq) and immune cell reconstitution were performed in human/mouse PDAC cell lines and a syngeneic orthotopic tumor transplantation model of KrasG12D-mutant and Trp53-deficient PDAC cells.

RESULTS

Regnase-1 expression was negatively correlated with the clinical outcomes and an independent predictor of poor relapse-free and overall survival in PDAC patients. Pancreas-specific Regnase-1 deletion in mice promoteed pancreatic cancer with PMN-MDSC infiltration and shortened their survival. A syngeneic orthotopic PDAC model exhibited that Regnase-1 downregulation accelerated tumor progression via recruitment of intratumor CD11b+ MDSCs. Mechanistically, Regnase-1 directly negatively regulated a variety of chemokines/cytokines important for MDSC recruitment and activation, including CXCL1, CXCL2, CSF2, and TGFβ, in pancreatic cancer cells. We subsequently showed that IL-1β-mediated Regnase-1 downregulation recruited MDSCs to tumor sites and promoted pancreatic cancer progression via mitigation of cytotoxic T lympohocytes-mediated antitumor immunity.

CONCLUSIONS

IL-1b-mediated Regnase-1 downregulation induces MDSCs and promotes pancreatic cancer through the evasion of anticancer immunity.

Ischemia prediction score (IsPS) in patients with strangulated small bowel obstruction: a retrospective cohort study

BACKGROUNDS

Intestinal ischemia of strangulated small bowel obstruction (SSBO) requires prompt identification and early intervention. This study aimed to evaluate the risk factors and develop a prediction model of intestinal ischemia requiring bowel resection in SSBO.

METHODS

This was a single-center, retrospective cohort study of consecutive patients underwent emergency surgery for SSBO from April 2007 to December 2021. Univariate analysis was performed to identify the risk factors for bowel resection in these patients. Two clinical scores (with contrasted computed tomography [CT] and without contrasted CT) were developed to predict intestinal ischemia. The scores were validated in an independent cohort.

RESULTS

A total of 127 patients were included, 100 in the development cohort (DC) and 27 in the validation cohort (VC). Univariate analysis showed that high white blood cell count (WBC), low base excess (BE), ascites and reduced bowel enhancement were significantly associated with bowel resection. The ischemia prediction score (IsPS) comprised 1 point each for WBC ≥ 10,000/L, BE ≤ -1.0 mmol/L, ascites, and 2 points for reduced bowel enhancement. The simple IsPS (s-IsPS, without contrasted CT) of 2 or more had a sensitivity of 69.4%, specificity of 65.4%. The modified IsPS (m-IsPS, with contrasted CT) of 3 or more had a sensitivity of 86.7%, specificity of 76.0%. AUC of s-IsPS was 0.716 in DC and 0.812 in VC, and AUC of m-IsPS was 0.838 and 0.814.

CONCLUSION

IsPS predicted possibility of ischemic intestinal resection with high accuracy and can help in the early identification of intestinal ischemia in SSBO.

The impact of cellular senescence and senescence‑associated secretory phenotype in cancer‑associated fibroblasts on the malignancy of pancreatic cancer

Cancer‑associated fibroblasts (CAFs) are implicated in the strong malignancy of pancreatic cancer (PC). Various CAF subtypes have different functions, and their heterogeneity likely influence the malignancy of PC. Meanwhile, it is known that senescent cells can create a tumor‑promoting microenvironment by inducing a senescence‑associated secretory phenotype (SASP). In the present study, the effects of individual differences in CAFs on PC malignancy were investigated with a focus on cellular senescence. First, primary cultures of CAFs from 8 PC patients were generated and co‑cultured with PC cell lines. This co‑culture assay showed that differences in CAFs induce differences in PC cell proliferation. It was further investigated which clinical factors affected the malignant potential of CAF and it was found that the difference of malignant potential of each CAF was marginally related to the age of original patients. Next, to verify the senescence of CAFs really affected the malignant potential of CAF, PCR array analysis of each CAF sample was performed and it was revealed that expression of genes about cellular senescence and SASP such as tumor protein p53, nuclear factor kappa B subunit 1, and IL6, are related to the malignant potential of CAFs impacting on PC proliferation. Finally, to elucidate the effect of p53‑mediated cellular senescence of CAFs on malignant potential of PC, it was examined whether CAFs with the treatment of p53 inhibitor affected PC cell proliferation in co‑culture assays. The treatment of CAFs with p53 inhibitor significantly suppressed PC cell proliferation. In addition, a comparison of the concentration of IL‑6, a SASP cytokine, in the co‑culture supernatant showed a significant decrease in the sample after p53 inhibitor treatment. In conclusion, the present results suggested that proliferation potential of PC may be related to p53‑mediated cellular senescence and SASP of CAFs.

[A Case of Long-Term Survival with Tumor Resection and DOX plus DTIC Therapy for Desmoid Tumor after FAP Surgery]

The patient is a 22-year-old, female. She had a family history of familial adenomatous polyposis(FAP)and a prophylactic total colorectal resection was performed for FAP at age of 18. She presented with fever and abdominal distention and palpated a mass with tenderness in the right lower abdomen. Contrast-enhanced CT scan of the abdomen showed a heterogeneous contrast effect around the tumor margins. With the diagnosis of intra-abdominal desmoid tumor, a partial duodenal resection, small bowel mass resection, and right fallopian tube resection were performed along with the tumor, and an artificial anus was created with the jejunum. Contrast-enhanced CT scan of the abdomen 16 months after resection of desmoid tumor showed a 6.5 cm long desmoid tumor recurrence in the mesentery. She received 5 courses of doxorubicin (DOX)plus dacarbazine(DTIC)therapy followed by continued NSAIDs. Seven years after the operation, she has been able to maintain the shrinkage of the recurrent tumor and is still on medication. Long-term surveillance is necessary because of the possibility of the appearance of other associated lesions in the future.

[A Case of Malignant Rectal B Cell Lymphoma That Was Difficult to Differentiate from Rectal Neuroendocrine Tumor]

A 74-year-old woman with a chief complaint of hematochezia was admitted to our hospital. Colonoscopy revealed a 2 cm submucosal tumor with an erosion in the Rb of the rectum. Biopsy showed various inflammatory cell clusters, but no malignant findings. Thoracoabdominal CT and abdominal MRI showed no abnormal findings other than that of rectal wall thickening. Somatostatin receptor scintigraphy performed on suspected rectal NET showed no abnormal accumulation. A total of 3 biopsies were performed, but a definitive diagnosis was not confirmed, and transanal rectal mucosal resection was performed for diagnostic purposes. Immunohistochemistry showed CD20(+)and bcl-2(+), and the lesion was diagnosed as malignant rectal B cell lymphoma. For 1 year postoperatively, the patient showed no recurrence. For this case, biopsy often failed to confirm a definitive diagnosis on rectal submucosal tumors. If the tumor is >1 cm in diameter in a rectal NET, a rectal resection with lymph node dissection is required, and anal function may be impaired. Local tumor excision for diagnosis and treatment may be worthwhile in rectal submucosal tumors if pre-resection diagnosis with biopsy is difficult.

[A Case of Nivolumab Responding to Multiple Lymph Node Metastases during Multidisciplinary Treatment for Esophageal Cancer]

In nivolumab therapy for unresectable advanced esophageal cancer, there are a few cases that show a complete response, and long-term survival can be expected in such cases. Here, we report a case in which nivolumab had a complete response to multiple lymph node metastases during multidisciplinary treatment for esophageal cancer and survived for a relatively long period despite being elderly. Examination of complete response cases provides us with significant insights in considering the unexplained biomarkers of immune checkpoint inhibitors and treatment discontinuation during complete response.

OMIP 078: A 31-parameter panel for comprehensive immunophenotyping of multiple immune cells in human peripheral blood mononuclear cells

This 31-parameter panel was developed for simultaneously measuring multiple immune cell populations including T cells, B cells, natural killer cells, dendritic cells, monocytes, and hematopoietic progenitor cells in human peripheral blood mononuclear cells. This panel enables the capture of individual immune dynamics and assessments of single-cell changes in the immune system that are associated with aging and diseases. This panel includes markers to separate the differentiation status of each cell population and might be applicable to studies of infectious and autoimmune diseases, as patient samples are usually limited in volume and require an analysis system that provides a relatively large amount of information.

[Successful R0 Resection of Hilar Cholangiocarcinoma by Extrahepatic Bile Duct Resection Due to Accompanying Liver Dysfunction after Neoadjuvant Gemcitabine/Cisplatin/S-1 Combination Chemotherapy-A Case Report]

A 79-year-old man was referred to our hospital for treatment of hilar cholangiocarcinoma with pathological evidence. FDG-PET/CT and EUS-FNA revealed regional lymph node metastasis and no distant metastasis before the treatment. He received 6 courses of neoadjuvant gemcitabine/cisplatin/S-1 combination chemotherapy, and the imaging studies revealed partial response. However, due to impairment of the liver after chemotherapy, it was difficult to perform subsequent major hepatectomy, and we decided to continue the chemotherapy. The impairment of the liver did not recover following 11 courses of chemotherapy; on the other hand, FDG uptake was diminished on FDG-PET, and cancer cells were not detected by repeated cytology and biopsy. Extrahepatic bile duct resection with dissection of regional lymph nodes was performed, and histopathological examinationof the resected specimensuggested R0 resection.

[A Case of Urothelial Carcinoma Who Underwent Pancreaticoduodenectomy and Was Diagnosed with Groove Pancreatitis and Preoperatively Suffered from Duodenal Stenosis]

We report a case of a highly advanced urothelial carcinoma accompanied by duodenal stenosis with pancreaticoduodenectomy. A6 6-year-old man presented with upper abdominal pain and vomiting. Acute pancreatitis and hydronephrosis were diagnosed with urgent hospitalization, but jaundice appeared, and stenosis of the duodenum was also found. Thus, we suspected groove pancreatitis or pancreatic cancer, and performed pancreaticoduodenectomy. However, poorly differentiated adenocarcinoma was observed in the retroperitoneal dissection surface in the intraoperative rapid tissue and right hemicolectomy, right nephrectomy, and right ureteral resection were added to the diagnosis. The final diagnosis was urothelial carcinoma. GEM plus CBDCAtherapy was administered as adjuvant chemotherapy. However, obstructive jaundice, acute cholangitis, and acute pancreatitis developed due to occlusion of the intestine due to local recurrence 4 months after surgery. We attempted to reduce yellowing by PTCD; perforation of the small intestine also occurred and a drainage tube was placed in the abdominal cavity. Although a lull condition was obtained, intestinal obstruction due to cancer peritonitis worsened and the patient died 8 months after the operation. In this case, there was no hematuria before surgery and cytology results of urine were negative, so a diagnosis of urinary tract cancer was difficult. There was no report of duodenal stenosis due to urothelial carcinoma.

[Multimodality Therapy for Cecal Cancer with Peritoneal Dissemination]

We report a case of cecal cancer with peritoneal dissemination. A 72-year-old man with cecal cancer(pT4N2M0H0P3, pStage IV )underwent ileocecal resection in 2010. The patient received 106 courses of chemotherapy(FOLFIRI plus Cmab) for peritoneal dissemination after surgery. However, follow-up CT performed 50 months after primary resection detected liver metastasis, which was resected in 2015. The patient received 19 courses of chemotherapy(FOLFIRI plus Cmab)after hepatectomy. The peritoneal dissemination with the diaphragm, retroperitoneal and right inguinal region, were growing 20 months after the 2nd operation. Surgical resection of the peritoneal dissemination was performed in 2016. The patient is alive 81 months after the 1st operation.

[The Experience of the Intensity Modulated Radiation Therapy for Abdominal Lymph Node Metastases from Gastric Cancer]

The recurrence ofgastric cancer has a poor prognosis in spite ofsystemic chemotherapy. We report three cases oflocal control ofdisease after the recurrence owing to intensity modulated radiation therapy(IMRT). The first case was a 66-yearsold man. He was received distal gastrectomy after neoadjuvant chemotherapy for advanced gastric cancer. Abdominal lymph node metastases appeared 1 year and 7 months after the surgery. IMRT was performed and he keeps CR for 1 year and 8 months. The second case was a 72-years-old man. He received proximal gastrectomy for early gastric cancer. Abdominal lymph node metastasis appeared 1 year and 9 months after the surgery. IMRT was performed and he keeps CR for 1 year. The third case was a 71-years-old woman. She received distal gastrectomy for advanced gastric cancer. Abdominal lymph node metastasis appeared 2 years after the surgery. IMRT was performed and she keeps CR for 10 months. We experienced longtime CR after IMRT against abdominal lymph node metastasis. IMRT could be one ofthe strategies ofthe comprehensive treatment for the recurrence of gastric cancer.

Rotatable high-resolution ARPES system for tunable linear-polarization geometry

A rotatable high-resolution angle-resolved photoemission spectroscopy (ARPES) system has been developed to utilize tunable linear-polarization geometries on the linear undulator beamline (BL-1) at Hiroshima Synchrotron Radiation Center. By rotating the whole ARPES measurement system, the photoelectron detection plane can be continuously changed from parallel to normal against the electric field vector of linearly polarized undulator radiation. This polarization tunability enables us to identify the symmetry of the initial electronic states with respect to the mirror planes, and to selectively observe the electronic states based on the dipole selection rule in the photoemission process. Specifications of the rotatable high-resolution ARPES system are described, as well as its capabilities with some representative experimental results.

[A Case of Angioimmunoblastic T-Cell Lymphoma Merged with Colorectal Cancer That We Were Able to Resect after a Chemotherapy Response]

The patient was 77-year-old man. He visited our hospital with the chief complaint of an abdominal mass in March 2015. We diagnosed the patient with transverse colon cancer and he was suspected of having malignant lymphoma. In March 2016, we attempted to perform right hemicolectomy for the transverse colon cancer, but it was difficult because swollen lymph nodes had formed a large mass with the surrounding tissue, including vessels of the mesentery. We could only complete the surgery after mesenteric lymph node biopsy. On the basis of the results of this biopsy, we diagnosed angioimmunoblastic Tcell lymphoma. At first, we administered THP-COP therapy for malignant lymphoma. However, after 3 courses of this therapy, the patient suddenly developed ileus due to the aforementioned colon cancer. According to enhanced CT performed at the onset of intestinal obstruction, chemotherapy dramatically reduced the size of the intraperitoneal lymph nodes. We therefore concluded that it was able to treat the colon cancer. We performed right hemicolectomy in June 2015. Angioimmunoblastic T-cell lymphoma comprises only 2-3% of all malignant lymphoma cases. We experienced a rare case of complications from angioimmunoblastic T-cell lymphoma and colorectal cancer.

[Successful Treatment of Local Recurrence of Advanced Gastric Cancer Using Curative Gastrectomy via Distal Pancreatectomy after Chemoradiotherapy]

The patient was a 65-year-old woman. She was diagnosed with advanced gastric cancer with liver invasion. After receiving systemic chemotherapy(S-1 plus PTX)for 3 months, she underwent total gastrectomy and partial hepatectomy in May 2008. Because she developed celiac artery circumference lymph node recurrence in November 2010 during postoperative adjuvant chemotherapy consisting of S-1 plus PTX, we changed her chemotherapy regimen to CPT-11 plus CDDP. We observed an increase in the size of the lymph nodes in August 2013 and the response was poor even after switching to DOC. However, the lymph nodes continued to increase in size and we administered radiotherapy of 60.4 Gy/33 Fr that resulted in shrinkage of the nodes. We observed an increase in lymph node size and pancreas invasion in September 2015, including an expansion of the mid pancreatic duct. We performed distal pancreatectomy without identifying the recurrence observed in November 2015 assuming it was an exacerbation. Six months after the surgery, the recurrence was not apparent. We report an example of long-term survival that was achieved for Stage IV gastric cancer. The patient underwent combined modality therapy for 8 years, and local recurrence was controlled via a primary operation.

[Two Cases of Small Intestinal Metastasis of Lung Cancer]

Case 1: A 66-year-old man who had undergone upper right lobe resection for large cell lung carcinoma 2 months earlier presented with abdominal pain and vomiting. Computed tomography showed intussusception of the small intestine. Partial resection of the small intestine was performed. The tumor was pathologically diagnosed as lung cancer metastasis to the small intestine. The patient died 30 days after surgery. Case 2: A 57-year-old man was admitted to hospital due to appetite loss. Computed tomography showed a large intestinal tumor and a small lung tumor, as well as multiple liver metastases and lymph node metastases. We diagnosed perforation of the small intestine tumor, and partial resection of small intestine was performed. Pathological examination and immunohistochemical staining revealed that the tumor was a metastatic adenocarcinoma, and the patient was diagnosed with small intestine metastasis of lung cancer. He died 75 days after surgery. Although small intestine metastasis of lung cancer is rare, the incidence is increasing. The prognosis of lung cancer metastasis of the small intestine is poor, and therefore, we must urgently decide the appropriate treatment.

[Intraluminal Type Gastrointestinal Stromal Tumor Resected by Single-Incision Percutaneous Endoscopic Intragastric Surgery--A Case Report]

We report a patient with gastric gastrointestinal stromal tumor (GIST) who underwent single-incision percutaneous endoscopic intragastric surgery. The patient was a 70-year-old man. Esophagogastroduodenoscopy and abdominal computed tomography revealed the presence of an intraluminal type gastric submucosal tumor, 4 cm in diameter, in the posterior wall of the gastric body. Laparoscopic partial gastrectomy was performed via a single incision made in the epigastric region. The postoperative course was uneventful. The pathological diagnosis was a low-risk GIST. This method is easy and safe to perform; therefore, we consider it to be an important option for the treatment of intraluminal type gastric GIST.

Coherent heavy quasiparticles in a CePt5 surface alloy

We report on the results of a high-resolution angle-resolved photoemission study on the ordered surface alloy CePt(5). The temperature dependence of the spectra show the formation of the coherent low-energy heavy-fermion band near the Fermi level. These experimental data are supported by a multiband model calculation in the framework of the dynamical mean-field theory.

Electronic structure of charge- and spin-controlled Sr(1-(x+y))La(x+y)Ti(1-x)Cr(x)O3

We present the electronic structure of Sr(1-(x+y))La(x+y)Ti(1-x)Cr(x)O3 investigated by high-resolution photoemission spectroscopy. In the vicinity of the Fermi level, it was found that the electronic structure was composed of a Cr 3d local state with the t(2g)3 configuration and a Ti 3d itinerant state. The energy levels of these Cr and Ti 3d states are well interpreted by the difference of the charge-transfer energy of both ions. The spectral weight of the Cr 3d state is completely proportional to the spin concentration x irrespective of the carrier concentration y, indicating that the spin density can be controlled by x as desired. In contrast, the spectral weight of the Ti 3d state is not proportional to y, depending on the amount of Cr doping.

Kink in the dispersion of layered strontium ruthenates

We present detailed energy dispersions near the Fermi level along the high symmetry line GammaX on the monolayer and bilayer strontium ruthenates Sr2RuO4 and Sr3Ru2O7, determined by high-resolution angle-resolved photoemission spectroscopy. A kink in the dispersion is clearly shown for the both ruthenates. The energy position of the kink and the slope in the low-energy part near the Fermi level are almost identical between them, whereas the dispersion in the high-energy part varies, like the behavior of the kink for the cuprate superconductors.

Rotation detection by optical heterodyne fiber gyro with frequency output

A fiber gyro with optical heterodyne detection is proposed. The experimental setup has been constructed and tested. Both the frequency difference in the fiber and the path-length difference between counterpropagating waves are eliminated to reduce output drift. An electronic circuit for phase-nulling detection has been constructed, which gives an electronic frequency output in proportion to the rotation rate. Direct frequency modulation of a single-mode laser diode has been adopted to reduce the noise that is due to the backward Rayleigh scattering. A short time resolution of the rotation rate of about 5 deg/h for an integration time of 1 sec. (0.0014 deg/sec) has been achieved with good linearity, for an integration time of 1 sec.

Fiber-optic laser gyro with easily introduced phase-difference bias

An optical system for easy introduction of phase-difference bias to optimize the sensitivity of the fiber-optic laser gyro is proposed. The theory of using a laser diode has been considered, and the rotation detection experiment has been performed. The experimental setup consists of a 300-m long single-mode optical fiber, individual optical components, and a laser diode stabilized by a thermal controller and an optical isolator. Short-time resolution of the rotation rate better than 0.87 mrad/sec has been achieved with good linearity.