Detachment fronts and the onset of dynamic friction

The dynamics of friction have been studied for hundreds of years, yet many aspects of these everyday processes are not understood. One such aspect is the onset of frictional motion (slip). First described more than 200 years ago as the transition from static to dynamic friction, the onset of slip is central to fields as diverse as physics, tribology, mechanics of earthquakes and fracture. Here we show that the onset of frictional slip is governed by three different types of coherent crack-like fronts: these are observed by real-time visualization of the net contact area that forms the interface separating two blocks of like material. Two of these fronts, which propagate at subsonic and intersonic velocities, have been the subject of intensive recent interest. We show that a third type of front, which propagates an order of magnitude more slowly, is the dominant mechanism for the rupture of the interface. No overall motion (sliding) of the blocks occurs until either of the slower two fronts traverses the entire interface.     

一种基于群体智能聚类的设备性能横向比较算法

提出了一种基于群体智能的设备性能横向比较算法,该算法将设备模式投影于二维平面上,然后依据群体智能聚类,实现设备性能的自组织聚类分析.为了提高群体智能聚类算法的运行效率,提出了利用主成分分析改善模式投影时的随机性.此外,为了减小参数选取对算法的影响,提出了一种更简单的相似度衡量公式.将改进后的算法与原算法进行比较,结果显示,改进算法的运行效率更高.利用改进算法对某中央空调的数据进行分析,验证了算法能满足设备性能自组织聚类的要求.     

Mechanism of action of interferon and ribavirin in treatment of hepatitis C

Since the identification of the hepatitis C virus, great strides have been made in the development of an antiviral therapy. As a crucial mediator of the innate antiviral immune response, interferon-alpha (IFN-alpha) was a natural choice for treatment. Whereas treatment with IFN-alpha alone achieved only modest success, the addition of the broad-spectrum antiviral agent ribavirin greatly improved responses. However, half of the infected individuals with chronic disease do not achieve sustained clearance of hepatitis C virus. To optimize current therapeutic strategies and to develop new therapies, a better understanding of the mechanism of action of IFN and ribavirin will be essential.     

The total synthesis of delphinine: A stereoselective synthesis of an advanced relay compound

Zusammenfassung Die stereoselektive Totalsynthese eines Delphininabbauproduktes wird beschrieben. Dieses Produkt, das 5 Ringe und 5 Substituenten besitzt, ist von Delphinin aus leicht zugänglich und kann deshalb als Relais-Verbindung für die Totalsynthese dieses Alkaloids dienen.

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Presented at a seminar at the Organic Chemistry Laboratory, ETH, Zurich, Switzerland on June 24, 1969.     

The total synthesis of delphinine: Resolution of the racemic relay compound into optical antipodes by an asymmetric reaction

Zusammenfassung Das totalsynthetische Razematdl 1a gab bei Reaktion mitl-Camphorsulfonylchlorid das Sulfonamid 2 und die optisch-aktive Base 1b. Die Identität dieser totalsynthetischen, optisch aktiven Base 1b mit dem entsprechenden Abbauprodukt von Delfinin wurde bewiesen.     

Depletion of the predominant B-cell population in immunoglobulin mu heavy-chain transgenic mice

The transgenic mouse line M54 was generated by introducing a functionally-rearranged immunoglobulin mu heavy-chain gene into the germ line of a C57B1/6 inbred mouse. Previous examination of the antibodies produced by B-cell hybridomas derived from transgenic M54 mice showed that the presence of the mu transgene grossly altered the immunoglobulin repertoire of unimmunized animals, suggesting that these mice suffer from a serious immunoregulatory perturbation. Studies presented here introduce a new perspective on this functional defect. We show that the lymphoid tissues from these transgenic mice lack virtually all conventional bone-marrow-derived B cells, which constitute the predominant B-cell population in normal mice and which typically produce primary and secondary antibody responses to T-cell-dependent antigens. Moreover, the bone marrow from transgenic M54 mice is depleted of pre-B lymphocytes, indicating a serious defect in early B-cell lymphopoiesis. In contrast, CD5 (Ly-1) B cells, a second B-cell population displaying a characteristic set of cell surface markers which are derived from distinct precursors in the peritoneum, are represented at normal frequencies in these transgenic mice. Thus, the presence of the rearranged immunoglobulin heavy-chain transgene in M54 mice results in an unexpected selective developmental defect that impairs the development of bone-marrow-derived pre-B and B cells without affecting Ly-1 B cells.