Peritectic transformation during cooling of iron-carbon alloy

Peritectic transformation behavior during cooling of iron-carbon alloys is simulated by a numerical analysis. The peritectic transformation, δ+L=γ, is divided into δ-γ transformation at δ/γ interface and L-γ solidification at γ/L interface, and proceeds by the following two mechanisms: (1) carbon diffusion from liquid (referred to as L) through austenite (γ) into δ-ferrite (δ) and (2) precipitation of austenite from δ-ferrite and crystallization of it from liquid due to cooling. Approximately 80% of the austenite formed during the peritectic transformation is the products of δ-y transformation, which may cause the generation of tensile stress in the solidification shell of cast steels due to the difference in density between δ-ferrite and austenite The amount of the δ-γ transformation is largest, when the initial carbon content is 0.17 mass%. However, when the transformation in a well-developed dendrite network structure is focused on, the carbon content for the maximum amount of the δ-γ transformation decreases to 0.14–0.16 mass%, which corresponds to the carbon content at which surface cracking of continuously cast slabs is reported to be most frequent     

Downregulation of polo-like kinase correlates with loss of proliferative ability of cardiac myocytes

Cardiac myocytes rapidly increase the cell number during the fetal and early neonatal period, but they lose their proliferative ability soon after birth. To understand the mechanism of how cardiac myocytes exit from the cell cycle, we examined the role of a newly identified serine/threonine kinase, polo-like kinase (Plk), in the process of proliferation of cardiac myocytes. Northern blot analysis revealed that Plk gene was abundantly expressed in cardiac myocytes and non-myocytes of fetal and neonatal rats but not in cardiocytes of adult rats. Western blot analysis showed that Plk protein was also detected only in fetal and neonatal hearts. During the early stage of cardiac differentiation. Plk expression was well correlated with the proliferative ability of cardiocytes. Plk mRNA was most abundant in undifferentiated embryonic stem (ES) cells and the mRNA levels decreased along with cardiac differentiation in the developing ES cell system. Once serum was deprived from the culture media, expression levels of Plk were markedly decreased and DNA was not synthesized in both cardiac myocytes and non-myocytes of neonatal rats. Re-addition of serum stimulated Plk gene expression and DNA synthesis in non-myocytes but not in cardiomyocytes. All these results taken together with the critical role of Plk in DNA synthesis in many cell types suggest that downregulation of Plk is important for the permanent withdrawal of cardiomyocytes from the cell cycle.     

Importance of polysynaptic inputs and horizontal connectivity in the generation of tetanus-induced long-term potentiation in the rat auditory cortex

Supragranular pyramidal neurons in the adult rat auditory cortex (AC) show marked long-term potentiation (LTP) of population spikes after tetanic white matter stimulation (TS). For determination of whether this marked LTP is specific to AC, LTP in rat AC slices was compared with LTP in slices of the visual cortex (VC). The amplitude of TS-induced LTP in AC was twice that in VC. LTP of EPSPs was also studied with perforated patch or whole-cell recording. Although the amplitude of TS-induced LTP of EPSPs in AC was larger that in VC, no cortical difference was found in LTP elicited by low-frequency stimulation paired with current injection. Neocortical LTP is dependent on the activation of NMDA receptors, and induction of LTP requires postsynaptic depolarization for removal of Mg2+ blockade of NMDA receptors. The postsynaptic depolarization elicited by TS in supragranular pyramidal neurons in AC was significantly larger than that in VC. Cutting of supragranular horizontal connections resulted in a decrease in the depolarization amplitude in AC but an increase in the depolarization amplitude in VC. The cortical difference in TS-induced LTP was diminished in the slices in which horizontal connections in supragranular layers were cut. The estimated density of horizontal axon collaterals of supragranular pyramidal neurons in AC was approximately twice that in VC. These results strongly suggest that the marked polysynaptic and postsynaptic depolarization during TS and the resulting marked LTP in AC are attributed to well developed horizontal axon collaterals of supragranular pyramidal neurons in AC.     

Solid Modeling Based on a New Paradigm

The technique of solid modeling is essential in CAD/CAM applications, and is currently well established. However, problems remain, such as the lack of uniformity in geometric computations and the lack of stability of Boolean operations of two solids. In this paper, we introduce a theoretical solid modeling system that operates on boundary representations of polyhedral objects and is based on a new paradigm. The characteristics of the system are the following: (I) in Boolean Operations and modeling transformations, all geometric computations are performed by the 4 × 4 determinant method or the 4 × 4 matrix method in homogeneous space, which allows the system to avoid division operations, (2) all geometric computations are performed by the exact integer arithmetic, which makes the geometric algorithms stable and simple, and (3) primitive solids are constructed consistently in the integer domain, and the consistency is assured throughout Boolean operations and transformations.     

Three-dimensional measurement of ice crystals in frozen dilute solution

A Micro-Slicer Image Processing System (MSIPS) has been applied to observe the ice crystal structures formed in frozen dilute solutions. Several characteristic parameters were also proposed to investigate the three-dimensional (3-D) morphology and distribution of ice crystals, based on their reconstructed images obtained by multi-slicing a frozen sample with the thickness of 5 μm. The values of characteristic parameters were determined for the sample images with the dimension of 530×700×1000 μm. The 3-D morphology of ice crystals was found to be a bundle of continuous or dendrite columns at any freezing condition. The equivalent diameter of ice crystals were in the range of 73–169 μm, and decreased exponentially with increasing freezing rate at the copper cooling plate temperature of −20 to −80 °C. At the T_cp −40 °C, the volumes of ice crystals were in the range of 4.6×10⁴ μm³ to 3.3×10⁷ μm³, and 36 ice columns were counted in the 3-D image.     

An increased ratio of interleukin-1 receptor antagonist to interleukin-1alpha in inflammatory skin diseases

IL-1 receptor antagonist (IL-1ra) is a cytokine that competitively binds the IL-1 receptor to antagonize IL-1 activity without any agonist function. Previous experiments indicated that the ratio of IL-1ra to IL-1alpha in the normal stratum corneum (SC) was much higher in the sun-exposed face than in the sun-protected area, upper arms. It was also reported by another laboratory that IL-1ra is increased in the lesional skin of psoriatic patients. This study was designed to measure the contents of IL-1alpha and IL-1ra in non-lesional and pathological SC obtained from inflammatory skin diseases including psoriasis and non-psoriatic dermatoses such as atopic dermatitis. The SC materials were obtained with a non-invasive tape-stripping method. Their soluble fractions were prepared and assayed for IL-1alpha and IL-1ra by enzyme-linked immunosorbent assays. As a result we confirmed the previous findings that the ratio of IL-1ra to IL-1alpha in the normal SC was much higher in the face than in the sun-protected sites, the trunk as well as extremities. Next, we found that IL-1alpha contents were significantly reduced in the SC samples obtained from inflammatory skin regardless of whether their IL-1ra contents increased or unchanged. Moreover, we noted that an increased ratio of IL-1ra to IL-1alpha in the SC was not specific to psoriasis, but was also found in other inflammatory skin diseases including atopic dermatitis. This ratio was found to become lower after successful treatment of these skin lesions with topical glucocorticoids. We conclude from these observations that the increased ratio of IL-1ra to IL-1alpha in the SC is a non-specific phenomenon that can occur in any inflammatory skin diseases regardless of the inflammatory pattern, probably reflecting a skin regulation process against various kinds of inflammation.     

Localization of matrix metalloproteinases-1, -2, and -9 and tissue inhibitor of metalloproteinase-2 in interstitial lung diseases

In interstitial lung diseases, deposition of extracellular matrix (ECM) in alveoli and degradation of ECM lead to pulmonary structural remodeling. The changes in ECM and the localization of matrix metalloproteinases (MMPs) and a tissue inhibitor of metalloproteinases (TIMP) in the lung tissues of patients with bronchiolitis obliterans organizing pneumonia (BOOP) and idiopathic pulmonary fibrosis (IPF) were investigated. Immunohistochemical analysis for the detection of fibronectin, collagen-I, -III, and -IV, smooth muscle actin, MMP-1 (interstitial collagenase), -2 (gelatinase A), and -9 (gelatinase B), and TIMP-2, and in situ hybridization for the detection of MMP-9 mRNA were performed. Western blotting of lung tissue homogenates was performed for MMP-2 and MMP-9. The gelatinolytic activities of the homogenates were also determined using gelatin zymography. Fibronectin and collagen-I, -III, and -IV were detected in the intra-alveolar fibrosis in addition to the interstitium of these diseases. MMP-1, MMP-2, MMP-9, and TIMP-2 were detected in the regenerated epithelial cells covering intra-alveolar fibrosis. Myofibroblasts in intra-alveolar fibrosis in BOOP showed predominant reaction for MMPs, and they ultrastructurally appeared to be phagocytosing collagen fibrils, and those of IPF showed a predominant reaction for TIMP-2. New vascularization in intra-alveolar fibrosis was exclusively observed in cases of BOOP, and the endothelial cells were positive for MMP-2. Western blotting showed the existence of a latent form of MMP-9 and latent and active forms of MMP-2, and gelatin zymography revealed that the ratio of active/latent forms of MMP-2 in BOOP is significantly larger than that in the control lungs. Predominant MMPs in BOOP may constitute the mechanism of reversibility of fibrotic changes in this disease. TIMP-2 in myofibroblasts in IPF may contribute to the stable ECM deposition and the irreversible pulmonary structural remodeling.     

Phase I study of raltitrexed (ZD-1694)

A multicenter cooperative phase I study of ZD-1694 (raltitrexed), a novel, folate-based thymidylate synthase (TS) inhibitor, was conducted with single and repeated doses in 30 patients with various malignant tumors. ZD-1694 was intravenously infused over 15 minutes. In the single-dose study, the initial dose was fixed at 1.0 mg/m2 (1n), and the dose was escalated stepwise up to 3.5 mg/m2 (3.5 n). Based on the results of the single-dose study, in the repeated-dose study, doses of 2.5 n and 3 n were infused every three weeks (3 weeks/one course). In principle, patients received 2 courses or more. Of the 29 eligible patients, 16 were in the single-dose study and 13 in the repeated-dose study. Adverse reactions were evaluated in all eligible patients. In the single-dose study, neutropenia, nausea/vomiting, diarrhea, and transaminase (GOT, GPT) increases, of grade 3 or higher, occurred at high doses of 3 n and 3.5 n. These were regarded as dose-limiting toxicities (DLT). DLT of grade 3 or higher were observed in 1 of 4 patients given 3 n and 2 of 4 patients given 3.5 n. These results suggested that the maximum tolerated dose (MTD) of ZD-1694 was 3.5 n (3.5 mg/m2). In the repeated-dose study, DLT of grade 3 or higher was observed in no more than one third of each dose group, 2 of the 6 patients given 2.5 n and 2 of the 7 patients given 3 n. These results suggested that 3 n (3.0 mg/m2), a dose nearer to MTD, was the recommended dose for the phase II study. Although transaminase increases were observed in all patients, in 12 of them the increase was grade 2 or lower and reversible. A pharmacokinetic investigation showed the mean elimination half life of ZD-1694 plasma concentration was 91.5 hours in the single-dose group and 119.1 hours in the repeated dose group. It was suggested that ZD-1694 is metabolized to polyglutamates after uptake and retained in the cells for a long duration. However, no accumulation was seen in plasma concentration of ZD-1694 following repeated doses at 3-weekly intervals. One PR was observed in a patient with colorectal cancer receiving 2.5 n in the repeated-dose study. Based on these results, the recommended dosage and administration for the phase II study of ZD-1694 was 3 n (3.0 mg/m2) intravenously infused over 15 minutes every 3 weeks.     

Inter‐annual variability of chlorophyll and sea‐ice in the Antarctic Divergence region: an attempt to derive their quantitative relationship

Inter‐annual variability in chlorophyll a (chl a) and sea‐ice concentration in the Antarctic Divergence (AD) region near 140°?E was examined using satellite sensor data in order to derive a quantitative relationship between the two. Sea‐viewing Wide Field‐of‐view Sensor (SeaWiFS) derived chl a and Special Sensor Microwave/Imager (SSM/I) derived sea‐ice concentration data during 1997–2003 were analysed. Mean chl a concentration south of 64°?S during the period between September and April (from austral spring to autumn) of each year was calculated. The mean chl a in 2001/2002 was extremely high (1.08?mg?m^?3) within the six periods between 1997/1998 and 2002/2003. Simply integrated indices on sea‐ice amount, such as the maximum sea‐ice extent in the winter season, annual integration of coverage area over ice edge to coast, were not able to explain inter‐annual variation of chl a, especially the highest chl a value in 2001/2002. We found a high correlation between the chl a south of 64°?S and the sea‐ice index, which might be due to the surface meltwater of the sea‐ice from the AD zone as a result of eddies. The quantitative relationship might have contributed to the prediction of phytoplankton blooms in this coastal region and demonstrated the impact of the sea‐ice extent on the Antarctic marine ecosystem.     

Streaming Algorithms for Biological Sequence Alignment on GPUs

In this paper, "Martini," a network interface controller chip for our original network called RHiNET, is described. Martini is designed to provide high-bandwidth and low-latency communication with a small overhead. To obtain high-performance communication, protected user-level zero-copy remote direct memory access (RDMA) communication functions are completely implemented by a hardwired logic. Also, to reduce the communication latency efficiently, we have proposed programmed I/O (PlO)-based communication mechanisms called "On the fly (OTF)" and have implemented them on Martini. The evaluation results show that Martini connected to a 64-bit/66-MHz peripheral component interconnect (PCI) bus achieves a 470-Mbyte maximum bidirectional bandwidth and a 1.74-musec minimum latency on host-to-host memory copying.