Impact Factor: outdated artefact or stepping-stone to journal certification?

A review of Garfield's journal impact factor and its specific implementation as the Thomson Reuters Impact Factor reveals several weaknesses in this commonly-used indicator of journal standing. Key limitations include the mismatch between citing and cited documents, the deceptive display of three decimals that belies the real precision, and the absence of confidence intervals. These are minor issues that are easily amended and should be corrected, but more substantive improvements are needed. There are indications that the scientific community seeks and needs better certification of journal procedures to improve the quality of published science. Comprehensive certification of editorial and review procedures could help ensure adequate procedures to detect duplicate and fraudulent submissions.Comment: 25 pages, 12 figures, 6 table

Ultrafast and high-throughput mass spectrometric assay for therapeutic drug monitoring of antiretroviral drugs in pediatric HIV-1 infection applying dried blood spots

Kaletra® (Abott Laboratories) is a co-formulated medication used in the treatment of HIV-1-infected children, and it contains the two antiretroviral protease inhibitor drugs lopinavir and ritonavir. We validated two new ultrafast and high-throughput mass spectrometric assays to be used for therapeutic drug monitoring of lopinavir and ritonavir concentrations in whole blood and in plasma from HIV-1-infected children. Whole blood was blotted onto dried blood spot (DBS) collecting cards, and plasma was collected simultaneously. DBS collecting cards were extracted by an acetonitrile/water mixture while plasma samples were deproteinized with acetone. Drug concentrations were determined by matrix-assisted laser desorption/ionization-triple quadrupole tandem mass spectrometry (MALDI-QqQ-MS/MS). The application of DBS made it possible to measure lopinavir and ritonavir in whole blood in therapeutically relevant concentrations. The MALDI-QqQ-MS/MS plasma assay was successfully cross-validated with a commonly used high-performance liquid chromatography (HPLC)–ultraviolet (UV) assay for the therapeutic drug monitoring (TDM) of HIV-1-infected patients, and it showed comparable performance characteristics. Observed DBS concentrations showed as well, a good correlation between plasma concentrations obtained by MALDI-QqQ-MS/MS and those obtained by the HPLC-UV assay. Application of DBS for TDM proved to be a good alternative to the normally used plasma screening. Moreover, collection of DBS requires small amounts of whole blood which can be easily performed especially in (very) young children where collection of large whole blood amounts is often not possible. DBS is perfectly suited for TDM of HIV-1-infected children; but nevertheless, DBS can also easily be applied for TDM of patients in areas with limited or no laboratory facilities

Toward nanofluids of ultra-high thermal conductivity

The assessment of proposed origins for thermal conductivity enhancement in nanofluids signifies the importance of particle morphology and coupled transport in determining nanofluid heat conduction and thermal conductivity. The success of developing nanofluids of superior conductivity depends thus very much on our understanding and manipulation of the morphology and the coupled transport. Nanofluids with conductivity of upper Hashin-Shtrikman (H-S) bound can be obtained by manipulating particles into an interconnected configuration that disperses the base fluid and thus significantly enhancing the particle-fluid interfacial energy transport. Nanofluids with conductivity higher than the upper H-S bound could also be developed by manipulating the coupled transport among various transport processes, and thus the nature of heat conduction in nanofluids. While the direct contributions of ordered liquid layer and particle Brownian motion to the nanofluid conductivity are negligible, their indirect effects can be significant via their influence on the particle morphology and/or the coupled transport

CSF1R mutations in hereditary diffuse leukoencephalopathy with spheroids are loss of function

Hereditary diffuse leukoencephalopathy with spheroids (HDLS) in humans is a rare autosomal dominant disease characterized by giant neuroaxonal swellings (spheroids) within the CNS white matter. Symptoms are variable and can include personality and behavioural changes. Patients with this disease have mutations in the protein kinase domain of the colony-stimulating factor 1 receptor (CSF1R) which is a tyrosine kinase receptor essential for microglia development. We investigated the effects of these mutations on Csf1r signalling using a factor dependent cell line. Corresponding mutant forms of murine Csf1r were expressed on the cell surface at normal levels, and bound CSF1, but were not able to sustain cell proliferation. Since Csf1r signaling requires receptor dimerization initiated by CSF1 binding, the data suggest a mechanism for phenotypic dominance of the mutant allele in HDLS

Metallic state in disordered quasi-one-dimensional conductors

The metallic state in conjugated polymers and single-walled carbon nanotubes: is studied by dielectric spectroscopy (8-600 GHz). We have found an intriguing correlation between scattering time (tau) and plasma frequency (omega (p)):tau (proportional to)omega (-1.3)(p). This relation conflicts with the usually applied models that only consider disorder. Based on the observed parallels with doped semiconductors, we argue that the interchain coupling t(perpendicular to) plays a role comparable to the doping level and that the unusual free-carrier dynamics in the metallic state can be explained when including the role of t(perpendicular to) in the conventional models

Frequency and temperature scaling in the conductivity and its structural consequences

We have studied the temperature (T) and frequency (ω/2π) dependence of the complex conductivity σ(ω, T) of several systems where hopping conduction is dominant: conducting carbon‐black/polymer composites as a function of carbon‐black (CB) concentration, aggregates of molecular cluster compounds as a function of the size and of the distance between the metal cores and polymers as a function of degree of doping. For all compounds the conductivity as a function of ω and T can be scaled onto single curves. Using an extension of the anomalous diffusion model the specific details of these curves for the CB composites are shown to be characteristic of the underlying fractal structure. The main features of the scaled dependence of σ(ω, T) of the randomly packed cluster compounds are well described by effective medium theories, except at low frequencies where percolation effects become important. Similar features are seen in polythiophene derivatives at doping levels above the percolation threshold

Frequency and temperature scaling of the conductivity in percolating fractal networks of carbon-black/polymer composites

We have measured the frequency ω/2π dependence of the complex conductivity (σ′ and σ′') of conducting composites of carbon-black particles in a non-conducting polymer matrix up to 0.6 THz. The concentration p ranges from just above the percolation threshold pc up to 33pc. Temperatures T were varied between 4.2 K and 300 K. When scaled to σDC, σ′(T, ω) shows a unique dependence on ω, independent of T. We show how this relation follows from the hopping mechanism and relate the data to the microscopic hopping parameter