Toyota

About: Toyota is a company organization based out in Safenwil, Switzerland. It is known for research contribution in the topics: Internal combustion engine & Battery (electricity). The organization has 40032 authors who have published 55003 publications receiving 735317 citations. The organization is also known as: Toyota Motor Corporation & Toyota Jidosha KK.

First-principles calculation of the structural, electronic, and vibrational properties of gallium nitride and aluminum nitride

Abstract: First-principles pseudopotential calculations have been performed on GaN and AlN in the wurtzite and zinc-blende structures. The mixed-basis approach is employed due to the localized nature of the valence charge density in these materials. In the stress calculation within the mixed-basis set, a correction term is introduced to the stress expression in order to make it consistent with the pressure given by the total-energy calculations. The lattice constants in the wurtzite structure are in good agreement with the experimental data. The band gap appears to be direct except for zinc-blende AlN, which has the conduction-band minimum at the X point. The effective mass of the electron is found to be nearly isotropic for both wurtzite GaN and AlN. The agreement of the optical \ensuremath{\Gamma}-phonon frequencies with the Raman experimental data is excellent for wurtzite GaN and good for wurtzite AlN, except for ${\mathit{A}}_{1}$--transverse-optical (${\mathit{A}}_{1}$-TO) mode. The calculated ${\mathit{A}}_{1}$-TO mode frequency of AlN is 11% smaller than the experimental value. Both GaN and AlN are found to have the wurtzite structure in the ground state.

Structural and material changes in the aging thorax and their role in crash protection for older occupants

Abstract: The human body undergoes a variety of changes as it ages through adulthood. These include both morphological (structural) changes (e.g., increased thoracic kyphosis) and material changes (e.g., osteoporosis). The purpose of this study is to evaluate structural changes that occur in the aging bony thorax and to assess the importance of these changes relative to the well-established material changes. The study involved two primary components. First, full-thorax computed tomography (CT) scans of 161 patients, age 18 to 89 years, were analyzed to quantify the angle of the ribs in the sagittal plane. A significant association between the angle of the ribs and age was identified, with the ribs becoming more perpendicular to the spine as age increased (0.08 degrees/year, p=0.012). Next, a finite element model of the thorax was used to evaluate the importance of this rib angle change relative to other factors associated with aging. A three-factor, two-level factorial design was used to assess the relative importance of rib cage morphology ("young" and "old" rib angle), thickness of the cortical shell (thick = "young" and thin = "old"), and the bone material properties ("young" and "old") on the force-deflection response and injury tolerance of the thorax. The simulations showed that the structural and material changes played approximately equal roles in modulating the force-deflection response of the thorax. Changing the rib angle to be more perpendicular to the spine increased the effective thoracic stiffness, while the "old" material properties and the thin cortical shell decreased the effective stiffness. The offsetting effects of these traits resulted in similar effective thoracic stiffness for the "elderly" and baseline thoracic models, which is consistent with cadaver data available in the literature. All three effects tended to decrease chest deflection tolerance for rib fractures, though the material changes dominated (a four- to six-fold increase in elements eliminated using a maximum strain criterion). The primary conclusion, therefore, is that an older person's thorax, relative to a younger, does not necessarily deform more in response to an applied force. The tolerable sternal deflection level is, however, much less.

Incidence of and risk factors for incisional hernia after abdominal surgery

Abstract: Background Few larger studies have estimated the incidence of incisional hernia (IH) after abdominal surgery. Methods Patients who had abdominal surgery between November 2009 and February 2011 were included in the study. The incidence rate and risk factors for IH were monitored for at least 180 days. Results A total of 4305 consecutive patients were registered. Of these, 378 were excluded because of failure to complete follow-up and 3927 patients were analysed. IH was diagnosed in 318 patients. The estimated incidence rates for IH were 5·2 per cent at 12 months and 10·3 per cent at 24 months. In multivariable analysis, wound classification III and IV (hazard ratio (HR) 2·26, 95 per cent confidence interval 1·52 to 3·35), body mass index of 25 kg/m2 or higher (HR 1·76, 1·35 to 2·30), midline incision (HR 1·74, 1·28 to 2·38), incisional surgical-site infection (I-SSI) (HR 1·68, 1·24 to 2·28), preoperative chemotherapy (HR 1·61, 1·08 to 2·37), blood transfusion (HR 1·46, 1·04 to 2·05), increasing age by 10-year interval (HR 1·30, 1·16 to 1·45), female sex (HR 1·26, 1·01 to 1·59) and thickness of subcutaneous tissue for every 1-cm increase (HR 1·18, 1·03 to 1·35) were identified as independent risk factors. Compared with superficial I-SSI, deep I-SSI was more strongly associated with the development of IH. Conclusion Although there are several risk factors for IH, reducing I-SSI is an important step in the prevention of IH. Registration number: UMIN000004723 (University Hospital Medical Information Network, http://www.umin.ac.jp/ctr/index.htm).