Measuring forest floor interception in a beech forest in Luxembourg

International audienceIn hydrological models evaporation from interception is often disregarded, combined with transpiration, or taken as a fixed percentage of rainfall. In general interception is not considered to be a significant process in rainfall-runoff modelling. However, it appears that on average interception can amount to 20?50% of the precipitation. Therefore, knowledge about the process of interception is important. Traditional research on interception mainly focuses on canopy interception and almost completely denies forest floor interception, although this is an important mechanism that precedes infiltration or runoff. Forest floor interception consists partly of interception by dry soil, partly of interception by short vegetation (mosses, grasses and creeping vegetation) and partly of interception by litter. This research concentrates on litter interception: to measure its quantities at point scale and subsequently to upscale it to the scale of a hydrotope. A special measuring device has been developed, which consists of a permeable upper basin filled with forest floor and a watertight lower basin. Both are weighed continuously. The device has been tested in the Huewelerbach catchment (Luxembourg). The preliminary measuring results show that the device is working properly. For November 2004, evaporation from interception is calculated to be 34% of the throughfall in the Huewelerbach catchment

Large angle magnetization dynamics measured by time-resolved ferromagnetic resonance

A time-resolved ferromagnetic resonance technique was used to investigate the magnetization dynamics of a 10 nm thin Permalloy film. The experiment consisted of a sequence of magnetic field pulses at a repetition rate equal to the magnetic systems resonance frequency. We compared data obtained by this technique with conventional pulsed inductive microwave magnetometry. The results for damping and frequency response obtained by these two different methods coincide in the limit of a small angle excitation. However, when applying large amplitude field pulses, the magnetization had a non-linear response. We speculate that one possible cause of the nonlinearity is related to self-amplification of incoherence, known as the Suhl instabilities.Comment: 23 pages, 8 figures, submitted to PR

Transcriptional profiling of microglia; current state of the art and future perspectives

Microglia are the tissue macrophages of the central nervous system (CNS) and the first to respond to CNS dysfunction and disease. Gene expression profiling of microglia during development, under homeostatic conditions, and in the diseased CNS provided insight in microglia functions and changes thereof. Single-cell sequencing studies further contributed to our understanding of microglia heterogeneity in relation to age, sex, and CNS disease. Recently, single nucleus gene expression profiling was performed on (frozen) CNS tissue. Transcriptomic profiling of CNS tissues by (single) nucleus RNA-sequencing has the advantage that it can be applied to archived and well-stratified frozen specimens. Here, we give an overview of the significant advances recently made in microglia transcriptional profiling. In addition, we present matched cellular and nuclear microglia RNA-seq datasets we generated from mouse and human CNS tissue to compare cellular versus nuclear transcriptomes from fresh and frozen samples. We demonstrate that microglia can be similarly profiled with cell and nucleus profiling, and importantly also with nuclei isolated from frozen tissue. Nuclear microglia transcriptomes are a reliable proxy for cellular transcriptomes. Importantly, lipopolysaccharide-induced changes in gene expression were conserved in the nuclear transcriptome. In addition, heterogeneity in microglia observed in fresh samples was similarly detected in frozen nuclei of the same donor. Together, these results show that microglia nuclear RNAs obtained from frozen CNS tissue are a reliable proxy for microglia gene expression and cellular heterogeneity and may prove an effective strategy to study of the role of microglia in neuropathology

All-optical generation of states for "Encoding a qubit in an oscillator"

Both discrete and continuous systems can be used to encode quantum information. Most quantum computation schemes propose encoding qubits in two-level systems, such as a two-level atom or an electron spin. Others exploit the use of an infinite-dimensional system, such as a harmonic oscillator. In "Encoding a qubit in an oscillator" [Phys. Rev. A 64 012310 (2001)], Gottesman, Kitaev, and Preskill (GKP) combined these approaches when they proposed a fault-tolerant quantum computation scheme in which a qubit is encoded in the continuous position and momentum degrees of freedom of an oscillator. One advantage of this scheme is that it can be performed by use of relatively simple linear optical devices, squeezing, and homodyne detection. However, we lack a practical method to prepare the initial GKP states. Here we propose the generation of an approximate GKP state by using superpositions of optical coherent states (sometimes called "Schr\"odinger cat states"), squeezing, linear optical devices, and homodyne detection.Comment: 4 pages, 3 figures. Submitted to Optics Letter

Spatially resolved ultrafast precessional magnetization reversal

Spatially resolved measurements of quasi-ballistic precessional magnetic switching in a microstructure are presented. Crossing current wires allow detailed study of the precessional switching induced by coincident longitudinal and transverse magnetic field pulses. Though the response is initially spatially uniform, dephasing occurs leading to nonuniformity and transient demagnetization. This nonuniformity comes in spite of a novel method for suppression of end domains in remanence. The results have implications for the reliability of ballistic precessional switching in magnetic devices.Comment: 17 pages (including 4 figures), submitted to Phys. Rev. Let

A novel SCN9A splicing mutation in a compound heterozygous girl with congenital insensitivity to pain, hyposmia and hypogeusia

Congenital insensitivity to pain (CIP) is a rare autosomal recessive disorder presenting with a spectrum of clinical features caused by mutations in different genes. A 10\u2010year\u2010old girl with CIP, hyposmia and hypogeusia, and her unaffected twin and parents underwent next generation sequencing of SCN9A exons and flanking splice sites. Transcript analysis from whole blood successfully assayed the effect of the mutation on the mRNA splicing by polymerase chain reaction amplification on cDNA and Sanger sequencing. We identified the novel splicing variant c.1108\u20102A>G compound with the p.Arg896Gln (c.2687G>A) missense mutation previously described in a homozygous patient. The new intronic variant was predicted to induce exon 10 skipping. Conversely, SCN9A mRNA assay demonstrated its partial deletion with a loss of 46 nucleotides causing a premature stop codon in position p.Gln369 (NP_002968). Genetic analysis showed that the two variants were biallelic, being the mother and brother heterozygous carriers of the missense mutation, and the father heterozygous for the splicing mutation. Skin biopsy showed lack of Meissner's corpuscles, loss of epidermal nociceptors and normal autonomic organ innervation. We report a novel splicing mutation and provide clues on its pathogenic effect, broadening the spectrum of genotypes and phenotypes associated to CIP

Inferring combinatorial association logic networks in multimodal genome-wide screens

Motivation: We propose an efficient method to infer combinatorial association logic networks from multiple genome-wide measurements from the same sample. We demonstrate our method on a genetical genomics dataset, in which we search for Boolean combinations of multiple genetic loci that associate with transcript levels

Broadband quadrature-squeezed vacuum and nonclassical photon number correlations from a nanophotonic device

We report the first demonstrations of both quadrature squeezed vacuum and photon number difference squeezing generated in an integrated nanophotonic device. Squeezed light is generated via strongly driven spontaneous four-wave mixing below threshold in silicon nitride microring resonators. The generated light is characterized with both homodyne detection and direct measurements of photon statistics using photon number-resolving transition edge sensors. We measure $1.0(1)$~dB of broadband quadrature squeezing (${\sim}4$~dB inferred on-chip) and $1.5(3)$~dB of photon number difference squeezing (${\sim}7$~dB inferred on-chip). Nearly-single temporal mode operation is achieved, with raw unheralded second-order correlations $g^{(2)}$ as high as $1.87(1)$ measured (${\sim}1.9$~when corrected for noise). Multi-photon events of over 10 photons are directly detected with rates exceeding any previous quantum optical demonstration using integrated nanophotonics. These results will have an enabling impact on scaling continuous variable quantum technology.Comment: Significant improvements and updates to photon number squeezing results and discussions, including results on single temporal mode operatio

Transverse optical plasmons in layered superconductors

We discuss the possible existance of transverse optical plasma modes in superlattices consisting of Josephson coupled superconducting layers. These modes appear as resonances in the current-current correlation function, as opposed to the usual plasmons which are poles in the density-density channel. We consider both bilayer superlattices, and single layer lattices with a spread of interlayer Josephson couplings. We show that our model is in quantitative agreement with the recent experimental observation by a number of groups of a peak at the Josephson plasma frequency in the optical conductivity of La$_{1.85}$Sr$_{0.15}$CuO$_4$Comment: Proceedings of LT21, in press, 4 pages, Latex with LTpaper.sty and epsfig.sty, 2 postscript figure

Intrinsic DNA damage repair deficiency results in progressive microglia loss and replacement

The DNA excision repair protein Ercc1 is important for nucleotide excision, double strand DNA break, and interstrand DNA crosslink repair. In constitutiveErcc1-knockout mice, microglia display increased phagocytosis, proliferation and an enhanced responsiveness to lipopolysaccharide (LPS)-induced peripheral inflammation. However, the intrinsic effects ofErcc1-deficiency on microglia are unclear. In this study,Ercc1was specifically deleted from Cx3cr1-expressing cells and changes in microglia morphology and immune responses at different times after deletion were determined. Microglia numbers were reduced with approximately 50% at 2-12 months afterErcc1deletion. Larger and more ramified microglia were observed followingErcc1deletion both in vivo and in organotypic hippocampal slice cultures.Ercc1-deficient microglia were progressively lost, and during this period, microglia proliferation was transiently increased.Ercc1-deficient microglia were gradually replaced by nondeficient microglia carrying a functionalErcc1allele. In contrast to constitutiveErcc1-deficient mice, microglia-specific deletion ofErcc1did not induce microglia activation or increase their responsiveness to a systemic LPS challenge. Gene expression analysis suggested thatErcc1deletion in microglia induced a transient aging signature, which was different from a priming or disease-associated microglia gene expression profile.</p