Quantum cascade laser based hybrid dual comb spectrometer

Four-wave-mixing-based quantum cascade laser frequency combs (QCL-FC) are a powerful photonic tool, driving a recent revolution in major molecular fingerprint regions, i.e. mid- and far-infrared domains. Their compact and frequency-agile design, together with their high optical power and spectral purity, promise to deliver an all-in-one source for the most challenging spectroscopic applications. Here, we demonstrate a metrological-grade hybrid dual comb spectrometer, combining the advantages of a THz QCL-FC with the accuracy and absolute frequency referencing provided by a free-standing, optically-rectified THz frequency comb. A proof-of-principle application to methanol molecular transitions is presented. The multi-heterodyne molecular spectra retrieved provide state-of-the-art results in line-center determination, achieving the same precision as currently available molecular databases. The devised setup provides a solid platform for a new generation of THz spectrometers, paving the way to more refined and sophisticated systems exploiting full phase control of QCL-FCs, or Doppler-free spectroscopic schemes

Development of communicative-pragmatic abilities in children with early cochlear implants

Cochlear Implants (CIs) enhance linguistic skills in deaf or hard of hearing children (D/HH). However, the benefits of CIs have not been sufficiently studied, especially with regard to communicative-pragmatics, i.e., the ability to communicate appropriately in a specific context using different expressive means, such as language and extralinguistic or paralinguistic cues. The study aimed to assess the development of communicative-pragmatic ability, through the Assessment Battery for Communication (ABaCo), in school-aged children with CIs, to compare their performance to a group of children with typical auditory development (TA), and to investigate if CI received under the age of 24 months promotes the typical development of such ability. Results show that children with CIs performed significantly worse than TA on the paralinguistic and contextual scales of the ABaCo. Finally, the age of first implantation had a significant role in the development of communicative-pragmatic ability

Frequency metrology of helium around 1083 nm and determination of the nuclear charge radius

We measure the absolute frequency of seven out of the nine allowed transitions between the 2$^3${\it S} and 2$^3${\it P} hyperfine manifolds in a metastable $^3$He beam by using an optical frequency comb synthesizer-assisted spectrometer. The relative uncertainty of our measurements ranges from $1\times 10^{-11}$ to $5\times 10^{-12}$, which is, to our knowledge, the most precise result for any optical $^3$He transition to date. The resulting $2^3${\it P}-2$^3${\it S} centroid frequency is $276\,702\,827\,204.8\,(2.4)$kHz. Comparing this value with the known result for the $^4$He centroid and performing {\em ab initio} QED calculations of the $^4$He-$^3$He isotope shift, we extract the difference of the squared nuclear charge radii $\delta r^2$ of $^3$He and $^4$He. Our result for $\delta r^2=1.074 (3)$ fm$^2$ disagrees by about $4\,\sigma$ with the recent determination [R. van Rooij {\em et al.}, Science {\bf 333}, 196 (2011)].Comment: 4 pages, 3 figures, 3 table

Early onset and enhanced growth of autochthonous mammary carcinomas in C3-deficient Her2/neu transgenic mice

Aside from its classical role in fighting infections, complement is an important, although poorly understood, component of the tumor microenvironment. In particular, the tumor growth-regulatory activities of complement remain under debate. To assess the role of the complement system in the progression of autochthonous mammary carcinomas, we have crossed complement component 3 (C3)-deficient (C3(−/−)) BALB/c male mice with BALB/c females expressing the activated rat Her2/neu oncogene (neuT). Although neuT transgenic mice develop spontaneous mammary cancers with 100% penetrance, a significantly shorter tumor latency (i.e., earlier onset of the first palpable tumor), a higher frequency of multiple tumors (multiplicity), and a dramatic increase in the tumor growth rate were found in neuT-C3(−/−) animals. The accelerated tumor onset observed in neuT-C3(−/−) mice was paralleled by an earlier onset of spontaneous lung metastases and by an increase in Her2 expression levels, primarily on the surface of tumor cells. The percentage of immune cells infiltrating neuT carcinomas was similar in C3-deficient and C3-proficient mice, with the exception of a significant increase in the frequency of regulatory T cells in neuT-C3(−/−) tumors. Of particular interest, the enhanced immunosuppression imparted by C3 deficiency clearly influenced the immunogenic phenotype of autochthonous mammary tumors as neuT-C3(−/−) malignant cells transplanted into syngeneic immunocompetent hosts gave rise to lesions with a significantly delayed kinetics and reduced incidence as compared with cells obtained from neuT C3-proficient tumors. Finally, increased blood vessel permeability was evident in neuT-C3(−/−) tumors, although a similar number of tumor vessels was found in neuT and neuT-C3(−/−) lesions. Altogether, these data suggest that complement plays a crucial role in the immunosurveillance and, possibly, the immunoediting of Her2-driven autochthonous mammary tumors

Fully Phase Stabilized Quantum Cascade Laser Frequency Comb

The road towards the realization of quantum cascade laser (QCL) frequency combs [1,2] has undoubtedly attracted ubiquitous attention from the scientific community. These devices promise to deliver an all-in-one (i.e. a single, miniature, active device) frequency comb synthesizer in a range as wide as the QCL spectral coverage itself (from about 4 microns to the THz range), with the unique possibility to tailor their spectral emission by band structure engineering. For these reasons, vigorous efforts have been spent to characterize the emission of four-wave-mixing (FWM) multi-frequency QCLs, aiming to seize their comb-like mode-locked operation [3–6]

Are mice good models for human neuromuscular disease? Comparing muscle excursions in walking between mice and humans

The mouse is one of the most widely used animal models to study neuromuscular diseases and test new therapeutic strategies. However, findings from successful pre-clinical studies using mouse models frequently fail to translate to humans due to various factors. Differences in muscle function between the two species could be crucial but often have been overlooked. The purpose of this study was to evaluate and compare muscle excursions in walking between mice and humans