Violation of a Bell-like inequality in single-neutron interferometry

Non-local correlations between spatially separated systems have been extensively discussed in the context of the Einstein, Podolsky and Rosen (EPR) paradox and Bell's inequalities. Many proposals and experiments designed to test hidden variable theories and the violation of Bell's inequalities have been reported; usually, these involve correlated photons, although recently an experiment was performed with (9)Be(+) ions. Nevertheless, it is of considerable interest to show that such correlations (arising from quantum mechanical entanglement) are not simply a peculiarity of photons. Here we measure correlations between two degrees of freedom (comprising spatial and spin components) of single neutrons; this removes the need for a source of entangled neutron pairs, which would present a considerable technical challenge. A Bell-like inequality is introduced to clarify the correlations that can arise between observables of otherwise independent degrees of freedom. We demonstrate the violation of this Bell-like inequality: our measured value is 2.051 +/- 0.019, clearly above the value of 2 predicted by classical hidden variable theories.     

Top-down signal from prefrontal cortex in executive control of memory retrieval.

Knowledge or experience is voluntarily recalled from memory by reactivation of the neural representations in the cerebral association cortex. In inferior temporal cortex, which serves as the storehouse of visual long-term memory, activation of mnemonic engrams through electric stimulation results in imagery recall in humans, and neurons can be dynamically activated by the necessity for memory recall in monkeys. Neuropsychological studies and previous split-brain experiments predicted that prefrontal cortex exerts executive control upon inferior temporal cortex in memory retrieval; however, no neuronal correlate of this process has ever been detected. Here we show evidence of the top-down signal from prefrontal cortex. In the absence of bottom-up visual inputs, single inferior temporal neurons were activated by the top-down signal, which conveyed information on semantic categorization imposed by visual stimulus-stimulus association. Behavioural performance was severely impaired with loss of the top-down signal. Control experiments confirmed that the signal was transmitted not through a subcortical but through a fronto-temporal cortical pathway. Thus, feedback projections from prefrontal cortex to the posterior association cortex appear to serve the executive control of voluntary recall.     

Regulation of myelopoiesis by proinflammatory cytokines in infectious diseases

Hematopoiesis is hierarchically orchestrated by a very small population of hematopoietic stem cells (HSCs) that reside in the bone-marrow niche and are tightly regulated to maintain homeostatic blood production. HSCs are predominantly quiescent, but they enter the cell cycle in response to inflammatory signals evoked by severe systemic infection or injury. Thus, hematopoietic stem and progenitor cells (HSPCs) can be activated by pathogen recognition receptors and proinflammatory cytokines to induce emergency myelopoiesis during infection. This emergency myelopoiesis counterbalances the loss of cells and generates lineage-restricted hematopoietic progenitors, eventually replenishing mature myeloid cells to control the infection. Controlled generation of such signals effectively augments host defense, but dysregulated stimulation by these signals is harmful to HSPCs. Such hematopoietic failure often results in blood disorders including chronic inflammatory diseases and hematological malignancies. Recently, we found that interleukin (IL)-27, one of the IL-6/IL-12 family cytokines, has a unique ability to directly act on HSCs and promote their expansion and differentiation into myeloid progenitors. This process resulted in enhanced production of neutrophils by emergency myelopoiesis during the blood-stage mouse malaria infection. In this review, we summarize recent advances in the regulation of myelopoiesis by proinflammatory cytokines including type I and II interferons, IL-6, IL-27, granulocyte colony-stimulating factor, macrophage colony-stimulating factor, and IL-1 in infectious diseases.     

Occurrence of biopterin in the wings ofMorpho butterflies

A blue fluorescent compound was isolated fromMorpho butterfly wings. Based on thin layer chromatographic, UV and CD-spectrophotometric and HPLC analyses, the blue fluorescent compound was identified as L-erythro biopterin. Biopterin is a major component of blue fluorescent pteridines in bothM. sulkowskyi andM. adonis. Pterin and isoxanthopterin can also be detected as minor components in these species. This paper is the first to report the presence of biopterin in butterfly wings.     

Was the universal common ancestry proved?

The question of whether or not all life on Earth shares a single common ancestor has been a central problem of evolutionary biology since Darwin. Although the theory of universal common ancestry (UCA) has gathered a compelling list of circumstantial evidence, as given in ref. 2, there has been no attempt to test statistically the UCA hypothesis among the three domains of life (eubacteria, archaebacteria and eukaryotes) by using molecular sequences. Theobald recently challenged this problem with a formal statistical test, and concluded that the UCA hypothesis holds. Although his attempt is the first step towards establishing the UCA theory with a solid statistical basis, we think that the test of Theobald is not sufficient enough to reject the alternative hypothesis of the separate origins of life, despite the Akaike information criterion (AIC) of model selection giving a clear distinction between the competing hypotheses.