Poincaré's “Les conceptions nouvelles de la matière”

We present a translation of Poincaré's hitherto untranslated 1912 essay together with a brief introduction describing the essay's contemporary interest, both for Poincaré scholarship and for the history and philosophy of atomism. In the introduction we distinguish two easily conflated strands in Poincaré's thinking about atomism, one focused on the possibility of deciding the atomic hypothesis, the other focused on the question whether it can ever be determined that the analysis of matter has a finite bound. We show that Poincaré admitted the decisiveness of Perrin's investigations for the existence of atoms; he did not, however, anticipate the kind of resolution of which the second question is susceptible in light of recent developments.     

The crystal structure of a voltage-gated sodium channel

Voltage-gated sodium (Na(V)) channels initiate electrical signalling in excitable cells and are the molecular targets for drugs and disease mutations, but the structural basis for their voltage-dependent activation, ion selectivity and drug block is unknown. Here we report the crystal structure of a voltage-gated Na(+) channel from Arcobacter butzleri (NavAb) captured in a closed-pore conformation with four activated voltage sensors at 2.7?? resolution. The arginine gating charges make multiple hydrophilic interactions within the voltage sensor, including unanticipated hydrogen bonds to the protein backbone. Comparisons to previous open-pore potassium channel structures indicate that the voltage-sensor domains and the S4-S5 linkers dilate the central pore by pivoting together around a hinge at the base of the pore module. The NavAb selectivity filter is short, ～4.6?? wide, and water filled, with four acidic side chains surrounding the narrowest part of the ion conduction pathway. This unique structure presents a high-field-strength anionic coordination site, which confers Na(+) selectivity through partial dehydration via direct interaction with glutamate side chains. Fenestrations in the sides of the pore module are unexpectedly penetrated by fatty acyl chains that extend into the central cavity, and these portals are large enough for the entry of small, hydrophobic pore-blocking drugs. This structure provides the template for understanding electrical signalling in excitable cells and the actions of drugs used for pain, epilepsy and cardiac arrhythmia at the atomic level.     

The landscape of recombination in African Americans

Recombination, together with mutation, gives rise to genetic variation in populations. Here we leverage the recent mixture of people of African and European ancestry in the Americas to build a genetic map measuring the probability of crossing over at each position in the genome, based on about 2.1 million crossovers in 30,000 unrelated African Americans. At intervals of more than three megabases it is nearly identical to a map built in Europeans. At finer scales it differs significantly, and we identify about 2,500 recombination hotspots that are active in people of West African ancestry but nearly inactive in Europeans. The probability of a crossover at these hotspots is almost fully controlled by the alleles an individual carries at PRDM9 (P?value 相似文献   

Coherent coupling of a superconducting flux qubit to an electron spin ensemble in diamond

During the past decade, research into superconducting quantum bits (qubits) based on Josephson junctions has made rapid progress. Many foundational experiments have been performed, and superconducting qubits are now considered one of the most promising systems for quantum information processing. However, the experimentally reported coherence times are likely to be insufficient for future large-scale quantum computation. A natural solution to this problem is a dedicated engineered quantum memory based on atomic and molecular systems. The question of whether coherent quantum coupling is possible between such natural systems and a single macroscopic artificial atom has attracted considerable attention since the first demonstration of macroscopic quantum coherence in Josephson junction circuits. Here we report evidence of coherent strong coupling between a single macroscopic superconducting artificial atom (a flux qubit) and an ensemble of electron spins in the form of nitrogen-vacancy colour centres in diamond. Furthermore, we have observed coherent exchange of a single quantum of energy between a flux qubit and a macroscopic ensemble consisting of about 3?×?10(7) such colour centres. This provides a foundation for future quantum memories and hybrid devices coupling microwave and optical systems.     

Only full-sibling families evolved eusociality

Arising from M. A. Nowak, C. E. Tarnita & E. O. Wilson 466, 1057-1062 (2010); Nowak et al. reply. The paper by Nowak et al. has the evolution of eusociality as its title, but it is mostly about something else. It argues against inclusive fitness theory and offers an alternative modelling approach that is claimed to be more fundamental and general, but which, we believe, has no practical biological meaning for the evolution of eusociality. Nowak et al. overlook the robust empirical observation that eusociality has only arisen in clades where mothers are associated with their full-sibling offspring; that is, in families where the average relatedness of offspring to siblings is as high as to their own offspring, independent of population structure or ploidy. We believe that this omission makes the paper largely irrelevant for understanding the evolution of eusociality.     

Recent developments in neuropsychological endophenotypes for schizophrenia: Development of the MATRICS battery,liability syndromes and the near future

Cognitive deficits are now recognized widely as core features of schizophrenia, and as major contributors to the clinical outcome of the disorder. They are also studied widely as ‘endophenotypes’, reflecting a growing consensus that schizophrenia is a broader, more multidimensional illness than the diagnostic criteria required for its formal diagnosis. This evolving view of cognition underlies its utilization in recent initiatives for intervention and assessment in schizophrenia. Two of these initiatives ar...     

First record of Climacia californica (Neuroptera: Sisyridae) and its host sponge, Ephydatia mulleri (Porifera: spongillidae), from Idaho with water quality relationships

The spongillafly, Climacia californica Chandler, and its sponge host, Ephydatia mulleri (Lieberkuhn), are reported from the state of Idaho for the first time. Climacia californica has not previously been reported from E. mulleri . Collections were made in the Burley – Twin Falls area, and detailed water quality data are provided for the first time for spongillafly larvae. The water quality data also expand the known tolerance limits of E. mulleri for water temperature, conductivity, pH, hardness, silica, and residue.