Herschel observations of embedded protostellar clusters in the Rosette molecular cloud

The Herschel OB young stellar objects survey (HOBYS) has observed the Rosette molecular cloud, providing an unprecedented view of its star formation activity. These new far-infrared data reveal a population of compact young stellar objects whose physical properties we aim to characterise. We compiled a sample of protostars and their spectral energy distributions that covers the near-infrared to submillimetre wavelength range. These were used to constrain key properties in the protostellar evolution, bolometric luminosity, and envelope mass and to build an evolutionary diagram. Several clusters are distinguished including the cloud centre, the embedded clusters in the vicinity of luminous infrared sources, and the interaction region. The analysed protostellar population in Rosette ranges from 0.1 to about 15 M_☉ with luminosities between 1 and 150 L_☉, which extends the evolutionary diagram from low-mass protostars into the high-mass regime. Some sources lack counterparts at near- to mid-infrared wavelengths, indicating extreme youth. The central cluster and the Phelps & Lada 7 cluster appear less evolved than the remainder of the analysed protostellar population. For the central cluster, we find indications that about 25% of the protostars classified as Class I from near- to mid-infrared data are actually candidate Class 0 objects. As a showcase for protostellar evolution, we analysed four protostars of low- to intermediate-mass in a single dense core, and they represent different evolutionary stages from Class 0 to Class I. Their mid- to far-infrared spectral slopes flatten towards the Class I stage, and the 160 to 70 μm flux ratio is greatest for the presumed Class 0 source. This shows that the Herschel observations characterise the earliest stages of protostellar evolution in detail

Modeling charge transport in C60-based self-assembled monolayers for applications in field-effect transistors

We have investigated the conductance properties of C60-containing self-assembled monolayers (SAMs), which are used in organic field-effect transistors, employing a combination of molecular-dynamics simulations, semiempirical electronic structure calculations and Landauer transport theory. The results reveal the close relation between the transport characteristics and the structural and electronic properties of the SAM. Furthermore, both local pathways of charge transport in the SAMs and the influence of structural fluctuations are analyzed.Comment: 10 figure

The Myth of Global Science

Scientific collaboration, in most cases, is seen a joint action on a global scale that involves researchers from not just one region or one country but instead forming an international network of researchers. This type of epistemic communities build up especially in the case of analytical modes of knowledge production. Rationales for a global science system are needs for complementary ressources in an increasingly specialized world. Further, information and communication technologies contributed to flatten the world for intense, yet spatially distant collaboration. Based on the large scale analysis of the production of scientific publications in six distinct technologies/scientific fields from 2004 to 2008 these notions may be challenged. The probability of a collaboration is a power-law function of the distance between the participating authors: The higher the spatial proximity, the higher the chance of a jointly written paper, i.e. collaboration. Two main universal effects can be isolated: an intra-country effect following a power law with a negative exponent, and an inter-country effect that shows features of a random distributed distance function. The former effect outcompetes the latter by a factor of around 50-100. This behaviour has inevitable consequences for the design of research collaboration programs by governments world-wide

What is the best initial treatment for orbital cellulitis in children?

Although antibiotics are the best initial treatment, surgical intervention is warranted when a child has: visual impairment, complete ophthalmoplegia, or well-defined abscess on presentation, or no clearly apparent clinical improvement by 24 hours (strength of recommendation [SOR]: C, based on patient-oriented case- series studies). Target antimicrobial therapy toward the common pathogens associated with pre- disposing factors for orbital cellulitis, such as sinusitis--and pay attention to local resistance patterns (SOR: C, based on patient-oriented case series)