Visualizing heavy fermions emerging in a quantum critical Kondo lattice

In solids containing elements with f orbitals, the interaction between f-electron spins and those of itinerant electrons leads to the development of low-energy fermionic excitations with a heavy effective mass. These excitations are fundamental to the appearance of unconventional superconductivity and non-Fermi-liquid behaviour observed in actinide- and lanthanide-based compounds. Here we use spectroscopic mapping with the scanning tunnelling microscope to detect the emergence of heavy excitations with lowering of temperature in a prototypical family of cerium-based heavy-fermion compounds. We demonstrate the sensitivity of the tunnelling process to the composite nature of these heavy quasiparticles, which arises from quantum entanglement of itinerant conduction and f electrons. Scattering and interference of the composite quasiparticles is used to resolve their energy-momentum structure and to extract their mass enhancement, which develops with decreasing temperature. The lifetime of the emergent heavy quasiparticles reveals signatures of enhanced scattering and their spectral lineshape shows evidence of energy-temperature scaling. These findings demonstrate that proximity to a quantum critical point results in critical damping of the emergent heavy excitation of our Kondo lattice system.     

Deciphering microRNA code in pain and inflammation: lessons from bladder pain syndrome

MicroRNAs (miRNAs), a novel class of molecules regulating gene expression, have been hailed as modulators of many biological processes and disease states. Recent studies demonstrated an important role of miRNAs in the processes of inflammation and cancer, however, there are little data implicating miRNAs in peripheral pain. Bladder pain syndrome/interstitial cystitis (BPS/IC) is a clinical syndrome of pelvic pain and urinary urgency/frequency in the absence of a specific cause. BPS is a chronic inflammatory condition that might share some of the pathogenetic mechanisms with its common co-morbidities inflammatory bowel disease (IBD), asthma and autoimmune diseases. Using miRNA profiling in BPS and the information about validated miRNA targets, we delineated the signaling pathways activated in this and other inflammatory pain disorders. This review projects the miRNA profiling and functional data originating from the research in bladder cancer and immune-mediated diseases on the BPS-specific miRNAs with the aim to gain new insight into the pathogenesis of this enigmatic disorder, and highlighting the common regulatory mechanisms of pain and inflammation.     

A single-step synthesis of nitrogen-doped graphene sheets decorated with cobalt hydroxide nanoflakes for the determination of dopamine

Nitrogen-doped reduced graphene oxide(NrGO)sheets decorated with Co(OH)_2nanoflakes were prepared by a single-step hydrothermal process.The morphological and structural characterizations of as synthesized Nr GO@Co(OH)_2nanoflakes were performed by field emission scanning electron microscopy(FESEM),EDX-mapping and X-ray diffraction(XRD).Nr GO@Co(OH)_2nanoflakes modified glassy carbon electrode(GCE)was used for electrochemical sensing of dopamine in neutral medium.The nanocomposite modified electrode showed enhanced electrochemical sensing ability for the detection of dopamine and the limit of detection(Lo D)was found to be 0.201μM with a sensitivity value of 0.0286±0.002 m A m M~(-1).Interference studies revealed that Nr GO@Co(OH)_2─GCE endow excellent selectivity for DA detection even in the presence of higher concentration of common co-existing physiological interfering analytes.Additionally,proposed sensor demonstrated excellent performance in urine samples with promising reproducibility and stability.     

Effect of SrCO3 addition on the dynamic compressive strength of ZTA

Ceramic parts usually experience dynamic load in armor applications. Therefore, studying the dynamic behaviors of ceramics is important. Limited data are available on the dynamic behaviors of ceramics;thus, it is helpful to predict the dynamic strength of ceramics on the basis of their mechanical properties. In this paper, the addition of SrCO3 into zirconia-toughened alumina (ZTA) was demonstrated to improve the fracture toughness of ZTA due to the formation of the SrAl12O19 (SA6) phase. The porosity of ZTA was found to be increased by the addition of SrCO3. These newly formed pores served as the nucleation sites of cracks under dynamic load;these cracks eventually coalesced to form damaged zones in the samples. Although the KIC values of the samples were improved, the dynamic strength was not en-hanced because of the increase in porosity;in fact, the dynamic strength of ZTA ceramics decreased with the addition of SrCO3.     

Heat shock protein gene expression during Xenopus development

Stress-induced heat shock protein gene expression is developmentally regulated during early embryogen esis of the frog, Xenopus laevis. For example, a number of heat shock protein genes, such as hsp70, hsp90, and ubiquitin are not heat-inducible until after the midblastula stage of embryogenesis. Furthermore, the family of small heat shock protein genes, hsp30, are differentially expressed after the midblastula stage as well as being regulated at the level of mRNA stability. Many of these stress proteins are also synthesized constitutively during oogenesis and embryogenesis during which they may act as molecular chaperones as well as being involved in sequestering proteins in an inactive state until required by the developing embryo. Furthermore the induction of these stress protein genes has been correlated with enhanced thermoresistance. During stressful conditions heat shock proteins probably prevent aggregation or misfolding of damaged protei ns within the embryo.     

A role for calpactin in calcium-dependent exocytosis in adrenal chromaffin cells

Stimulation of bovine adrenal chromaffin cells results in a rise in the concentration of cytosolic calcium which triggers the release of catecholamines by exocytosis. Several cytosolic proteins that bind to secretory granule membranes in a calcium-dependent manner have been implicated in exocytosis and some belong to a family of calcium-binding proteins, the annexins. One of these, calpactin, is a tetramer consisting of two heavy and two light chains (relative molecular masses 36,000 and 10,000 respectively) and can aggregate and fuse membranes in vitro in the presence of arachidonic acid. Calpactin is found at the cell periphery and is phosphorylated when chromaffin cells are stimulated. We show here that both calpactin and calpactin heavy chain (p36) reconstitute secretion in permeabilized chromaffin cells in which secretion has been reduced as a result of leakage of cellular components. This effect is inhibited by an affinity-purified antibody against p36. Secretion from permeabilized cells is inhibited by a synthetic annexin-consensus peptide, but not by a nonspecific hydrophobic peptide; this inhibition is reversed by p36. Our results indicate that either calpactin or p36 is essential for exocytosis.     

The dynamics of measles in sub-Saharan Africa

Although vaccination has almost eliminated measles in parts of the world, the disease remains a major killer in some high birth rate countries of the Sahel. On the basis of measles dynamics for industrialized countries, high birth rate regions should experience regular annual epidemics. Here, however, we show that measles epidemics in Niger are highly episodic, particularly in the capital Niamey. Models demonstrate that this variability arises from powerful seasonality in transmission-generating high amplitude epidemics-within the chaotic domain of deterministic dynamics. In practice, this leads to frequent stochastic fadeouts, interspersed with irregular, large epidemics. A metapopulation model illustrates how increased vaccine coverage, but still below the local elimination threshold, could lead to increasingly variable major outbreaks in highly seasonally forced contexts. Such erratic dynamics emphasize the importance both of control strategies that address build-up of susceptible individuals and efforts to mitigate the impact of large outbreaks when they occur.