The re-emergence of hyphenated history-and-philosophy-of-science and the testing of theories of scientific change

A basic premise of hyphenated history-and-philosophy-of-science is that theories of scientific change have to be based on empirical evidence derived from carefully constructed historical case studies. This paper analyses one such systematic attempt to test philosophical claims, describing its historical context, rationale, execution, and limited impact.     

Controlling inelastic light scattering quantum pathways in graphene

Inelastic light scattering spectroscopy has, since its first discovery, been an indispensable tool in physical science for probing elementary excitations, such as phonons, magnons and plasmons in both bulk and nanoscale materials. In the quantum mechanical picture of inelastic light scattering, incident photons first excite a set of intermediate electronic states, which then generate crystal elementary excitations and radiate energy-shifted photons. The intermediate electronic excitations therefore have a crucial role as quantum pathways in inelastic light scattering, and this is exemplified by resonant Raman scattering and Raman interference. The ability to control these excitation pathways can open up new opportunities to probe, manipulate and utilize inelastic light scattering. Here we achieve excitation pathway control in graphene with electrostatic doping. Our study reveals quantum interference between different Raman pathways in graphene: when some of the pathways are blocked, the one-phonon Raman intensity does not diminish, as commonly expected, but increases dramatically. This discovery sheds new light on the understanding of resonance Raman scattering in graphene. In addition, we demonstrate hot-electron luminescence in graphene as the Fermi energy approaches half the laser excitation energy. This hot luminescence, which is another form of inelastic light scattering, results from excited-state relaxation channels that become available only in heavily doped graphene.     

The production of leucylphenylalanine anhydride by a variant ofStreptomyces noursei

Résumé A partir de cultures deStreptomyces noursei, variante No. 5286, on a isolé la 3-benzyl-6-isobutyl-2, 5-dioxopipérazine, en plus des quatre dioxopipérazines disubstituées dont la présence a été signalée précédemment; on n'a pas obtenu de preuve de l'existence d'un dérivé 3-benzylidène-6-isobutyl-ou 3-benzyl-6-isobutylidènecorrespondant à la 3-benzyl-6-benzylidène-2,5-dioxopipérazine déjà connue.     

The Relevance of Systems Thinking in the Quest for Multifinal Social Enterprises

Human deprivation and suffering around the world are increasing despite the efforts of traditional aid-based approaches focused on alleviating poverty and improving the quality of life for marginalized communities. There is ample evidence that billions of dollars in aid money have been expended on development projects that are fundamentally unsustainable. On the other hand, social enterprises, which improve lives and livelihoods through practical market-based approaches, are growing in number. Systems Thinking can be especially helpful in navigating the complexity and chaos inherent in social ventures in developing communities. Lack of clarity in the roles, responsibilities, and returns for the various stakeholders epitomizes this chaos and is a major contributor to the failure of such projects. By employing Systems Thinking, entrepreneurs can establish accountability mechanisms, ensure equity for all stakeholders, and facilitate system sustainability. Though much research exists on both Systems Thinking and social enterprise, few sources discuss how Systems Thinking can be practically applied to conceptualize, build, and sustain social enterprises in an easy-to-understand manner. This paper synthesizes definitions of the tenets of Systems Thinking including interdependence, holism, multifinality, equifinality, differentiation, regulation, abstraction, and leverage points. The relevance of each of these tenets to social entrepreneurship is described, and further reinforced, with examples. A practical understanding of these tenets can empower entrepreneurs as they navigate chaotic environments in the quest for social enterprises that create win–win situations for all stakeholders.     

Structural basis of highly conserved ribosome recycling in eukaryotes and archaea

Ribosome-driven protein biosynthesis is comprised of four phases: initiation, elongation, termination and recycling. In bacteria, ribosome recycling requires ribosome recycling factor and elongation factor G, and several structures of bacterial recycling complexes have been determined. In the eukaryotic and archaeal kingdoms, however, recycling involves the ABC-type ATPase ABCE1 and little is known about its structural basis. Here we present cryo-electron microscopy reconstructions of eukaryotic and archaeal ribosome recycling complexes containing ABCE1 and the termination factor paralogue Pelota. These structures reveal the overall binding mode of ABCE1 to be similar to canonical translation factors. Moreover, the iron-sulphur cluster domain of ABCE1 interacts with and stabilizes Pelota in a conformation that reaches towards the peptidyl transferase centre, thus explaining how ABCE1 may stimulate peptide-release activity of canonical termination factors. Using the mechanochemical properties of ABCE1, a conserved mechanism in archaea and eukaryotes is suggested that couples translation termination to recycling, and eventually to re-initiation.     

Genome sequence of the Brown Norway rat yields insights into mammalian evolution

The laboratory rat (Rattus norvegicus) is an indispensable tool in experimental medicine and drug development, having made inestimable contributions to human health. We report here the genome sequence of the Brown Norway (BN) rat strain. The sequence represents a high-quality 'draft' covering over 90% of the genome. The BN rat sequence is the third complete mammalian genome to be deciphered, and three-way comparisons with the human and mouse genomes resolve details of mammalian evolution. This first comprehensive analysis includes genes and proteins and their relation to human disease, repeated sequences, comparative genome-wide studies of mammalian orthologous chromosomal regions and rearrangement breakpoints, reconstruction of ancestral karyotypes and the events leading to existing species, rates of variation, and lineage-specific and lineage-independent evolutionary events such as expansion of gene families, orthology relations and protein evolution.     

Virology: independent virus development outside a host

Viruses are thought to be functionally inactive once they are outside and independent of their host cell. Here we describe an exceptional property of a newly discovered virus that infects a hyperthermophilic archaeon growing in acidic hot springs: the lemon-shaped viral particle develops a very long tail at each of its pointed ends after being released from its host cell. The process occurs only at the temperature of the host's habitat (75-90 degrees C) and it does not require the presence of the host cell, an exogenous energy source or any cofactors. This host-independent morphological development may be a strategy for viral survival in an environment that is unusually harsh and has limited host availability.     

On the prevention of haematogenous tumour metastasis to liver and lung

Summary Vascular endothelium is lined by a layer of alpha, 2, macroglobulin (AMG). This protide is believed to regulate the rate of extravasation of tumor cells. Experiments are described which show that increasing the deposition of AMG (enhancing its production and blocking its lysis) reduces the incidence of tumour metastases to liver and lung.