Hideki Hasegawa

Bio: Hideki Hasegawa is an academic researcher from Hokkaido University. The author has contributed to research in topics: Schottky diode & Molecular beam epitaxy. The author has an hindex of 52, co-authored 513 publications receiving 13043 citations. Previous affiliations of Hideki Hasegawa include University of Tokyo.

Considerations on Double Exchange

Abstract: Zener has suggested a type of interaction between the spins of magnetic ions which he named "double exchange." This occurs indirectly by means of spin coupling to mobile electrons which travel from one ion to the next. We have calculated this interaction for a pair of ions with general spin $S$ and with general transfer integral, $b$, and internal exchange integral $J$.One result is that while the states of large total spin have both the highest and lowest energies, their average energy is the same as for the states of low total spin. This should be applicable in the high-temperature expansion of the susceptibility, and if it is, indicates that the high-temperature Curie-Weiss constant $\ensuremath{\theta}$ should be zero, and $\frac{1}{\ensuremath{\chi}}$ vs $T$ a curved line. This is surprising in view of the fact that the manganites, in which double exchange has been presumed to be the interaction mechanism, obey a fairly good Curie-Weiss law.The results can be approximated rather well by a simple semiclassical model in which the spins of the ion cores are treated classically. This model is capable of rather easy extension to the problem of the whole crystal, but the resulting mathematical problem is not easily solved except in special circumstances, e.g., periodic disturbances (spin waves).

Unified disorder induced gap state model for insulator–semiconductor and metal–semiconductor interfaces

Abstract: The energy location for the interface state density N s s minimum of the insulator–semiconductor (I–S) interface and the Fermi‐level pinning position at the metal–semiconductor (M–S) interface are shown to coincide and to lie at the same position of 5.0 eV from the vacuum level for major tetrahedral semiconductors. Neither the unified defect model nor the metal induced gap statemodel can explain the novel striking correlation between the I–S and M–S interfaces. The correlation as well as the observed peculiar photoionization behavior of the I–S interface are explained by the novel unified disorder induced gap state (DIGS) model where DIGS pin or restrict the movement of the surfaceFermi level. The above characteristic energy, E HO, is shown to be the Fermi energy of the DIGS spectrum which is given by the hybrid orbital energy of the s p 3 bond of the host. The DIGS model explains remarkably well the behavior of the M–S interface formed on the bare or oxide covered semiconductor surface as well as the various features of N s s distribution of the I–S interface. The correlation between the DIGS‐free heterojunction (S–S) interface and M–S/I–S interface is explained by the fact that E HO is a universal reference energy level of the host which is invariant under any off‐diagonal interactions, as is evidenced by the alignment of transition metal deep levels, DX centers and EL2 with respect to E HO. Band offset at the S–S interface is proposed to be determined by the alignment of E HO which inevitably involves formation of interface dipole when two E HO levels lie at different positions from the vacuum level.

Hepatocellular carcinoma: treatment with intraarterial iodized oil with and without chemotherapeutic agents.

Abstract: Thirty-one patients with hepatocellular carcinoma (HCC) were given either an intraarterial injection of iodized poppyseed oil (Lipiodol) alone (group A, n = 6), an emulsion of iodized oil and doxorubicin hydrochloride (Adriamycin) (group B, n = 15), or chemoembolization with the same emulsion followed by gelatin sponge (Gelfoam) particles (group C, n = 10) Hepatic resection was subsequently performed The frequencies of complete necrosis of tumor in the main lesion, daughter tumors, tumor thrombus, and foci of intracapsular invasion were evaluated in the cut surface of the resected specimen Group C demonstrated the best therapeutic effects, showing complete necrosis of the main lesion in 83% (P less than 01), daughter tumors in 53% (P less than 01), tumor thrombus in 17%, and foci of intracapsular invasion in 67% These results are superior to those reported previously for chemoembolization without iodized oil Group B showed better results than group A, but the difference was not significant Iodized

DOCK180, a major CRK-binding protein, alters cell morphology upon translocation to the cell membrane.

Abstract: CRK belongs to a family of adaptor proteins that consist mostly of SH2 and SH3 domains. Far Western blotting with CRK SH3 has demonstrated that it binds to 135- to 145-, 160-, and 180-kDa proteins. The 135- to 145-kDa protein is C3G, a CRK SH3-binding guanine nucleotide exchange protein. Here, we report on the molecular cloning of the 180-kDa protein, which is designated DOCK180 (180-kDa protein downstream of CRK). The isolated cDNA contains a 5,598-bp open reading frame encoding an 1,866-amino-acid protein. The deduced amino acid sequence did not reveal any significant homology to known proteins, except that an SH3 domain was identified at its amino terminus. To examine the function of DOCK180, a Ki-Ras farnesylation signal was fused to the carboxyl terminus of DOCK180, a strategy that has been employed successfully for activation of adaptor-binding proteins in vivo. Whereas wild-type DOCK180 accumulated diffusely in the cytoplasm and did not have any effect on cell morphology, farnesylated DOCK180 was localized on the cytoplasmic membrane and changed spindle 3T3 cells to flat, polygonal cells. These results suggest that DOCK180 is a new effector molecule which transduces signals from tyrosine kinases through the CRK adaptor protein.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

AASLD PRACTICE GUIDELINE Management of Hepatocellular Carcinoma: An Update

Abstract: Since the publication of the American Association for the Study of Liver Diseases (AASLD) practice guidelines on the management of hepatocellular carcinoma (HCC) in 2005, new information has emerged that requires that the guidelines be updated. The full version of the new guidelines is available on the AASLD Web site at http://www.aasld.org/practiceguidelines/ Documents/Bookmarked%20Practice%20Guidelines/ HCCUpdate2010.pdf. Here, we briefly describe only new or changed recommendations.

Neurotrophins: roles in neuronal development and function.

Abstract: Neurotrophins regulate development, maintenance, and function of vertebrate nervous systems. Neurotrophins activate two different classes of receptors, the Trk family of receptor tyrosine kinases and p75NTR, a member of the TNF receptor superfamily. Through these, neurotrophins activate many signaling pathways, including those mediated by ras and members of the cdc-42/ras/rho G protein families, and the MAP kinase, PI-3 kinase, and Jun kinase cascades. During development, limiting amounts of neurotrophins function as survival factors to ensure a match between the number of surviving neurons and the requirement for appropriate target innervation. They also regulate cell fate decisions, axon growth, dendrite pruning, the patterning of innervation and the expression of proteins crucial for normal neuronal function, such as neurotransmitters and ion channels. These proteins also regulate many aspects of neural function. In the mature nervous system, they control synaptic function and synaptic plasticity, while continuing to modulate neuronal survival.