Synchronization of deposition of daily growth layers in the cuticle of the cockroachBlaberus fuscus by gating of moult

Summary InBlaberus fuscus, combined light/dark-warm/cold cycles induce a rhythm of moulting. Most of the moults take place in the middle of the dark cold phases. Because of a stable phase-relation between moulting time and endocuticle growth rhythm, the latter is synchronized with the environmental cycles, too; lamellated layers are deposited during the light warm phases, which correspond to the time of resting of the cockroaches. Therefore, the cuticle growth is internally synchronized with rhythmic locomotory activity and metabolic rhythms.     

Variable and conserved neutralization antigens of human immunodeficiency virus

Human immunodeficiency virus type 1 (HIV-1, HTLV-III/LAV), the retrovirus responsible for acquired immune deficiency syndrome (AIDS), shows a high degree of genetic polymorphism, particularly in the env gene. We have examined sera from rabbits and guinea pigs immunized with gp130, a recombinant env glycoprotein, and sera from HIV-1-infected subjects, to test their capacity to neutralize a panel of genetically divergent HIV-1 isolates. The sera raised against recombinant antigen specifically neutralized the virus strain from which the env gene was cloned (HTLV-IIIB), but not an independent isolate (HTLV-IIIRF). One rabbit serum tested on seven isolates cross-neutralized two at lower titres. In contrast, human sera from Britain and Uganda, chosen for ability to neutralize HTLV-IIIRF, cross-neutralized six other HIV-1 isolates. When serum and isolate were derived from the same subject, the serum was in some cases effective at slightly lower concentrations (higher titres). Human complement did not affect neutralization titres. These findings indicate that genetically diverse HIV-1 isolates carry both variable and widely conserved antigenic epitopes for neutralizing antibodies. The identification of shared epitopes may help the development of protective vaccines.     

地图投影

在地图学中，地图投影是指建立地球表面上一点与投影平面上点之间的一一对应关系。地图投影的目的是通过将不可展的球面投影到一个可展曲面上，然后将该曲面展开成为一个平面，来保证空间信息在地域上的连续性、完整性和可测度性。根据美国著名地图投影专家J．P．Snyder统计，世界上地图投影种类现有256种。     

Correlated electron emission in multiphoton double ionization

Electronic correlations govern the dynamics of many phenomena in nature, such as chemical reactions and solid state effects, including superconductivity. Such correlation effects can be most clearly investigated in processes involving single atoms. In particular, the emission of two electrons from an atom--induced by the impact of a single photon, a charged particle or by a short laser pulse--has become the standard process for studies of dynamical electron correlations. Atoms and molecules exposed to laser fields that are comparable in intensity to the nuclear fields have extremely high probabilities for double ionization; this has been attributed to electron-electron interaction. Here we report a strong correlation between the magnitude and the direction of the momentum of two electrons that are emitted from an argon atom, driven by a femtosecond laser pulse (at 38 TW cm(-2)). Increasing the laser intensity causes the momentum correlation between the electrons to be lost, implying that a transition in the laser-atom coupling mechanism takes place.     

Volatile content of lunar volcanic glasses and the presence of water in the Moon's interior

The Moon is generally thought to have formed and evolved through a single or a series of catastrophic heating events, during which most of the highly volatile elements were lost. Hydrogen, being the lightest element, is believed to have been completely lost during this period. Here we make use of considerable advances in secondary ion mass spectrometry to obtain improved limits on the indigenous volatile (CO(2), H(2)O, F, S and Cl) contents of the most primitive basalts in the Moon-the lunar volcanic glasses. Although the pre-eruptive water content of the lunar volcanic glasses cannot be precisely constrained, numerical modelling of diffusive degassing of the very-low-Ti glasses provides a best estimate of 745 p.p.m. water, with a minimum of 260 p.p.m. at the 95 per cent confidence level. Our results indicate that, contrary to prevailing ideas, the bulk Moon might not be entirely depleted in highly volatile elements, including water. Thus, the presence of water must be considered in models constraining the Moon's formation and its thermal and chemical evolution.     

Antiviral treatment is more effective than smallpox vaccination upon lethal monkeypox virus infection

There is concern that variola virus, the aetiological agent of smallpox, may be used as a biological weapon. For this reason several countries are now stockpiling (vaccinia virus-based) smallpox vaccine. Although the preventive use of smallpox vaccination has been well documented, little is known about its efficacy when used after exposure to the virus. Here we compare the effectiveness of (1) post-exposure smallpox vaccination and (2) antiviral treatment with either cidofovir (also called HPMPC or Vistide) or with a related acyclic nucleoside phosphonate analogue (HPMPO-DAPy) after lethal intratracheal infection of cynomolgus monkeys (Macaca fascicularis) with monkeypox virus (MPXV). MPXV causes a disease similar to human smallpox and this animal model can be used to measure differences in the protective efficacies of classical and new-generation candidate smallpox vaccines. We show that initiation of antiviral treatment 24 h after lethal intratracheal MPXV infection, using either of the antiviral agents and applying various systemic treatment regimens, resulted in significantly reduced mortality and reduced numbers of cutaneous monkeypox lesions. In contrast, when monkeys were vaccinated 24 h after MPXV infection, using a standard human dose of a currently recommended smallpox vaccine (Elstree-RIVM), no significant reduction in mortality was observed. When antiviral therapy was terminated 13 days after infection, all surviving animals had virus-specific serum antibodies and antiviral T lymphocytes. These data show that adequate preparedness for a biological threat involving smallpox should include the possibility of treating exposed individuals with antiviral compounds such as cidofovir or other selective anti-poxvirus drugs.     

Hit-and-run planetary collisions

Terrestrial planet formation is believed to have concluded in our Solar System with about 10 million to 100 million years of giant impacts, where hundreds of Moon- to Mars-sized planetary embryos acquired random velocities through gravitational encounters and resonances with one another and with Jupiter. This led to planet-crossing orbits and collisions that produced the four terrestrial planets, the Moon and asteroids. But here we show that colliding planets do not simply merge, as is commonly assumed. In many cases, the smaller planet escapes from the collision highly deformed, spun up, depressurized from equilibrium, stripped of its outer layers, and sometimes pulled apart into a chain of diverse objects. Remnants of these 'hit-and-run' collisions are predicted to be common among remnant planet-forming populations, and thus to be relevant to asteroid formation and meteorite petrogenesis.