[FIP1L1::PDGFRA-positive chronic eosinophilic leukemia presenting with multiple ulcers of oral cavity and gastrointestinal tract].

A 66-year-old man developed multiple erosions and pain in the lips and mouth, fever, and black stools. There was persistent bleeding from the lip erosions. When he was admitted to our hospital, his white blood cell count increased to 53,420/µl with 3% eosinophils, and hemoglobin decreased to 3.1 g/dl. Bone marrow biopsy revealed an elevated eosinophil level (24.0%) with markedly toxic granules. Gastrointestinal endoscopy revealed multiple ulcers and erosions in the pharynx, esophagus, stomach, and colon. Histopathological diagnosis indicated nonspecific inflammation with poor infiltration of eosinophils. Bone marrow FISH test was positive for 4q12 deletion (FIP1L1::PDGFRA), leading to the diagnosis of FIP1L1::PDGFRA-positive chronic eosinophilic leukemia. Following initiation of oral administration of imatinib 100 mg/day, the number of eosinophils decreased rapidly, and normalized 2 days after the start of imatinib. The mucosal lesions showed significant improvement and were diagnosed as leukemia-associated lesions. Based on the clinical course of our patient, multiple oral cavity and gastrointestinal ulcers could be the initial presentation in this leukemia.

Probing hole spin transport of disorder quantum dots via Pauli spin-blockade in standard silicon transistors.

Single hole transport and spin detection is achievable in standard p-type silicon transistors owing to the strong orbital quantization of disorder based quantum dots. Through the use of the well acting as a pseudo-gate, we discover the formation of a double-quantum dot system exhibiting Pauli spin-blockade and investigate the magnetic field dependence of the leakage current. This enables attributes that are key to hole spin state control to be determined, where we calculate a tunnel couplingtcof 57µeV and a short spin-orbit lengthlSOof 250 nm. The demonstrated strong spin-orbit interaction at the interface when using disorder based quantum dots supports electric-field mediated control. These results provide further motivation that a readily scalable platform such as industry standard silicon technology can be used to investigate interactions which are useful for quantum information processing.

High-temperature operation of a silicon qubit.

This study alleviates the low operating temperature constraint of Si qubits. A qubit is a key element for quantum sensors, memories, and computers. Electron spin in Si is a promising qubit, as it allows both long coherence times and potential compatibility with current silicon technology. Si qubits have been implemented using gate-defined quantum dots or shallow impurities. However, operation of Si qubits has been restricted to milli-Kelvin temperatures, thus limiting the application of the quantum technology. In this study, we addressed a single deep impurity, having strong electron confinement of up to 0.3 eV, using single-electron tunnelling transport. We also achieved qubit operation at 5-10 K through a spin-blockade effect based on the tunnelling transport via two impurities. The deep impurity was implemented by tunnel field-effect transistors (TFETs) instead of conventional FETs. With further improvement in fabrication and controllability, this work presents the possibility of operating silicon spin qubits at elevated temperatures.

Electronic Magnetization of a Quantum Point Contact Measured by Nuclear Magnetic Resonance.

We report an electronic magnetization measurement of a quantum point contact (QPC) based on nuclear magnetic resonance (NMR) spectroscopy. We find that NMR signals can be detected by measuring the QPC conductance under in-plane magnetic fields. This makes it possible to measure, from Knight shifts of the NMR spectra, the electronic magnetization of a QPC containing only a few electron spins. The magnetization changes smoothly with the QPC potential barrier height and peaks at the conductance plateau of 0.5×2e^{2}/h. The observed features are well captured by a model calculation assuming a smooth potential barrier, supporting a no bound state origin of the 0.7 structure.

Dynamic creation of a topologically-ordered Hamiltonian using spin-pulse control in the Heisenberg model.

Hamiltonian engineering is an important approach for quantum information processing, when appropriate materials do not exist in nature or are unstable. So far there is no stable material for the Kitaev spin Hamiltonian with anisotropic interactions on a honeycomb lattice, which plays a crucial role in the realization of both Abelian and non-Abelian anyons. Here, we show two methods to dynamically realize the Kitaev spin Hamiltonian from the conventional Heisenberg spin Hamiltonian using pulse-control techniques based on the Baker-Campbell-Hausdorff (BCH) formula. In the first method, the Heisenberg interaction is changed into Ising interactions in the first process of the pulse sequence. In the next process of the first method, we transform them to a desirable anisotropic Kitaev spin Hamiltonian. In the second more efficient method, we show that if we carefully design two-dimensional pulses that vary depending on the qubit location, we can obtain the desired Hamiltonian in only one step of applying the BCH formula. As an example, we apply our methods to spin qubits based on quantum dots, in which the effects of both the spin-orbit interaction and the hyperfine interaction are estimated.

Large nuclear overhauser fields detected in vertically coupled double quantum dots.

We report the electrical induction and detection of dynamic nuclear polarization in the spin-blockade regime of double GaAs vertical quantum dots. The nuclear Overhauser field measurement relies on bias voltage control of the interdot spin exchange coupling and measurement of dc current at variable external magnetic fields. The largest Overhauser field observed was about 4 T, corresponding to a nuclear polarization approximately 40% for the electronic g factor typical of these devices, |g*| approximately 0.25. A phenomenological model is proposed to explain these observations.

Response to cyclosporine therapy in patients with myelodysplastic syndrome: a clinical study of 12 cases and literature review.

Cyclosporine (CyA) was administered to 12 patients with myelodysplastic syndrome (MDS), and a response (major erythroid response, according to International Working Group criteria) was observed in 7 patients (58.3%). The median duration of response was 18 months (range, 3-22 months). Two patients are still responding and continuing to take CyA. Three patients stopped because of malignancy complications. To identify variables associated with responsiveness to CyA therapy, we analyzed the treatments of 72 MDS patients, comprising the 12 new patients and 60 patients previously described in the literature. Responses were observed in 44 of the 72 patients (61.1%). Univariate analyses revealed that higher daily dose of CyA (P for trend test, .007) and shorter disease duration (median, 5 months versus 17.5 months, P = .04) were factors significantly associated with response. No significant associations were observed between response and bone marrow features such as erythroid hypoplasia or hypoplastic marrow. Multivariate analysis also demonstrated that high CyA dose (>5 mg/kg per day) was significantly associated with response (P = .02). The present study showed that CyA therapy is useful for MDS patients with any marrow cellularity. Shorter disease duration is a pretreatment variable correlated with response, and a higher CyA dose results in a higher response rate.

Nuclear-spin-induced oscillatory current in spin-blockaded quantum dots.

We show experimentally that electron transport through GaAs-based double quantum dots can be affected by ambient nuclear spin states in a certain regime where transport is blocked in the absence of electron spin flip. Current through the dots oscillates in time with a period up to 200 s depending on magnetic field. Oscillation is quenched by application of a continuous wave ac magnetic field which can induce nuclear magnetic resonance in 71Ga or 69Ga. A possible mechanism for dynamically polarizing the nuclear spins is proposed.

Spontaneous remission of Epstein-Barr virus-negative non-Hodgkin's lymphoma after withdrawal of cyclosporine in a patient with refractory anemia.

A 70-year-old man presented with pancytopenia in August 2000, and the results of a bone marrow examination performed in January 2001 confirmed the diagnosis of refractory anemia. He was treated with cyclosporine (CsA) at 3.3 mg/kg per day, and the pancytopenia improved. The patient complained of epigastralgia 21 months later, and a gastric endoscopic examination showed an ulcer with a cleaved bank. A biopsy revealed diffuse large B-cell lymphoma. In situ hybridization analysis detected no Epstein-Barr virus (EBV) in the lymphoma. CsA treatment was discontinued, and a gastrectomy was performed 31 days later. A detailed histologic examination revealed no infiltration of abnormal B-cells in the resected stomach. Although EBV-positive lymphoma is a known complication of immunosuppressive therapy, no causal association between immunosuppressants and EBV-negative lymphoma has been established. The spontaneous remission observed after the withdrawal of CsA treatment suggests that immunosuppressive therapy can be a pathogenic factor in a subset of EBV-negative lymphomas.