Lattice Distortion and Octupole Ordering Model in CexLa1-xB6

Possible order parameters of the phase IV in CexLa1-xB6 are discussed with special attention to the lattice distortion recently observed. A \Gamma_{5u}-type octupole order with finite wave number is proposed as the origin of the distortion along the [111] direction. The \Gamma_8 crystalline electric field (CEF) level splits into three levels by a mean field with the \Gamma_{5u} symmetry. The ground and highest singlets have the same quadrupole moment, while the intermediate doublet has an opposite sign. It is shown that any collinear order of \Gamma_{5u}-type octupole moment accompanies the \Gamma_{5g}-type ferro-quadrupole order, and the coupling of the quadrupole moment with the lattice induces the distortion. The cusp in the magnetization at the phase transition is reproduced, but the internal magnetic field due to the octupole moment is smaller than the observed one by an order of magnitude.Comment: 5 pages, 4 figures, submitted to J. Phys. Soc. Jp

Non-Collinear Magnetism due to Orbital Degeneracy and Multipolar Interactions

The origin of non-collinear magnetism under quadrupolar ordering is investigated with CeB6 taken as a target system. The mode-mixing effect among 15 multipoles is analyzed based on the Ginzburg-Landau free energy. Then the lower magnetic transition temperature and the order parameters are derived within the mean-field approximation. In the presence of pseudo-dipole-type interactions for the next-nearest neighbors, the observed pattern of non-collinear ordering is indeed stabilized for certain set of interaction parameters. The stability of the phase III' in the magnetic field is also explained, which points to the importance of the next-nearest-neighbor octupole-octupole interaction. Concerning the phase IV in CexLa1-xB6 with x ~ 0.75, a possibility of pure octupole ordering is discussed based on slight modifications of the strength of interactions.Comment: 12 pages, 7 figures, 3 tables, to appear in J. Phys. Soc. Jpn. 70 (6) (2001

Interpocket polarization model for magnetic structures in rare-earth hexaborides

The origin of peculiar magnetic structures in cubic rare-earth (R) hexaborides RB_6 is traced back to their characteristic band structure. The three sphere-like Fermi surfaces induce interpocket polarization of the conduction band as a part of a RKKY-type interaction. It is shown for the free-electron-like model that the interpocket polarization gives rise to a broad maximum in the intersite interaction I(q) around q=(1/4,1/4,1/2) in the Brillouin zone. This maximum is consistent with the superstructure observed in R=Ce, Gd and Dy. The wave-number dependence of I(q) is independently extracted from analysis of the spin-wave spectrum measured for NdB_6. It is found that I(q) obtained from fitting the data has a similarly to that derived by the interpocket polarization model, except that the absolute maximum now occurs at (0,0,1/2) in consistency with the A-type structure. The overall shape of I(q) gives a hint toward understanding an incommensurate structure in PrB_6 as well.Comment: 5 pages, 3 figures, submitted to J.Phys.Soc.Jp

Augmented-reality-assisted K-wire placement for glenoid component positioning in reversed shoulder arthroplasty: a proof-of-concept study

The accuracy of the implant’s post-operative position and orientation in reverse shoulder arthroplasty is known to play a significant role in both clinical and functional outcomes. Whilst technologies such as navigation and robotics have demonstrated superior radiological outcomes in many fields of surgery, the impact of augmented reality (AR) assistance in the operating room is still unknown. Malposition of the glenoid component in shoulder arthroplasty is known to result in implant failure and early revision surgery. The use of AR has many promising advantages, including allowing the detailed study of patient-specific anatomy without the need for invasive procedures such as arthroscopy to interrogate the joint’s articular surface. In addition, this technology has the potential to assist surgeons intraoperatively in aiding the guidance of surgical tools. It offers the prospect of increased component placement accuracy, reduced surgical procedure time, and improved radiological and functional outcomes, without recourse to the use of large navigation or robotic instruments, with their associated high overhead costs. This feasibility study describes the surgical workflow from a standardised CT protocol, via 3D reconstruction, 3D planning, and use of a commercial AR headset, to AR-assisted k-wire placement. Post-operative outcome was measured using a high-resolution laser scanner on the patient-specific 3D printed bone. In this proof-of-concept study, the discrepancy between the planned and the achieved glenoid entry point and guide-wire orientation was approximately 3 mm with a mean angulation error of 5°

Valuation of New Products in the Face of Consumer Income Disparity

The objective of this research is to begin exploring the welfare effects of new food product introductions and to determine whether such effects vary depending on the income classification of the customer base to which the products are introduced. In other words, when new products are introduced to both high- and low-income markets, is there a significant difference in estimated welfare effects that can be attributed to differences in consumer-base income levels? In an application involving new bottled juice introductions, we do, in fact, find notable differences in welfare effects accruing to different income-class cohorts. Our results provide important evidence of the need for an even greater understanding of new product welfare effects and how these effects vary across population groups and certain new product claims

Valuation of New Products in the Face of Consumer Income Disparity

The objective of this research is to begin exploring the welfare effects of new food product introductions and to determine whether such effects vary depending on the income classification of the customer base to which the products are introduced. In other words, when new products are introduced to both high- and low-income markets, is there a significant difference in estimated welfare effects that can be attributed to differences in consumer-base income levels? In an application involving new bottled juice introductions, we do, in fact, find notable differences in welfare effects accruing to different income-class cohorts. Our results provide important evidence of the need for an even greater understanding of new product welfare effects and how these effects vary across population groups and certain new product claims.compensating variation, differentiated products, distance metrics, new product valuation, retailing, Consumer/Household Economics,

A role for Rac1 activity in malignant progression of sebaceous skin tumors

The small GTPase Rac1 is crucial for maintaining stem cells (SCs) in mammalian epidermis, and Rac1 activation leads to SC expansion. Loss or inhibition of Rac1 correlates with decreased frequency of skin cancer formation in a chemical carcinogenesis model. Here, we have addressed whether Rac1 activation would enhance carcinogenesis and result in tumor progression. We used K14 Delta NLef1 mice, a model for differentiated sebaceous adenomas (SAs), and activated Rac1 in an epidermis-specific manner (K14L61Rac1). Surprisingly, Rac1 activation did not change the incidence and frequency of sebaceous tumors. However, tumors, which occurred exclusively in K14 Delta NLef1/K14L61Rac1 double-transgenic mice, were poorly differentiated resembling malignant sebaceous tumors and were termed sebaceous carcinoma-like tumors (SCLTs). Compared with SAs, SCLTs showed an aberrant pattern of cell proliferation, invasive growth and less abundant expression of sebocyte differentiation markers, including stearoyl-CoA desaturase-1 and adipophilin. Interestingly, the adnexal SC marker Lrig1 was upregulated in SCLTs, showing that active Rac1 leads to the accumulation of sebocyte precursors in the context of K14 Delta NLef1-induced skin tumors. In a search for targets of Rac1, we found cancer progression-related proteins, Dhcr24/Seladin1 and Nuclear protein 1/P8, to be strongly regulated in SCLTs. At last, Rac1 and Dhcr24/Seladin1 were detected in human sebaceous tumors demonstrating a potential high impact of our findings for human skin disease. This is the first study showing that Rac1 activity can lead to malignant progression of skin tumors