http://repositorium.sdum.uminho.pt/bitstream/1822/48763/1/1-s2.0-S037026931200857X-main.pdf

Observation of a new particle in the search for the Standard Model Higgs boson with the ATLAS detector at the LHC

We discuss the theoretical bases that underpin the automation of the computations of tree-level and next-to-leading order cross sections, of their matching to parton shower simulations, and of the merging of matched samples that differ by light-parton multiplicities. We present a computer program, MadGraph5 aMC@NLO, capable of handling all these computations — parton-level fixed order, shower-matched, merged — in a unified framework whose defining features are flexibility, high level of parallelisation, and human intervention limited to input physics quantities. We demonstrate the potential of the program by presenting selected phenomenological applications relevant to the LHC and to a 1-TeV e + e − collider. While next-to-leading order results are restricted to QCD corrections to SM processes in the first public version, we show that from the user viewpoint no changes have to be expected in the case of corrections due to any given renormalisable Lagrangian, and that the implementation of these are well under way.

/pdf/the-automated-computation-of-tree-level-and-next-to-leading-4etm0g6w46.pdf

The automated computation of tree-level and next-to-leading order differential cross sections, and their matching to parton shower simulations

In both metazoan development and metastatic cancer, migrating cells must carry out a detailed, complex program of sensing cues, binding substrates, and moving their cytoskeletons. The linker cell in Caenorhabditis elegans males undergoes a stereotyped migration that guides gonad organogenesis, occurs with precise timing, and requires the nuclear hormone receptor NHR-67. To better understand how this occurs, we performed RNA-seq of individually staged and dissected linker cells, comparing transcriptomes from linker cells of third-stage (L3) larvae, fourth-stage (L4) larvae, and nhr-67-RNAi–treated L4 larvae. We observed expression of 8,000–10,000 genes in the linker cell, 22–25% of which were up- or down-regulated 20-fold during development by NHR-67. Of genes that we tested by RNAi, 22% (45 of 204) were required for normal shape and migration, suggesting that many NHR-67–dependent, linker cell-enriched genes play roles in this migration. One unexpected class of genes up-regulated by NHR-67 was tandem pore potassium channels, which are required for normal linker-cell migration. We also found phenotypes for genes with human orthologs but no previously described migratory function. Our results provide an extensive catalog of genes that act in a migrating cell, identify unique molecular functions involved in nematode cell migration, and suggest similar functions in humans.

https://science.sciencemag.org/content/sci/256/5054/184.full.pdf

Alzheimer's disease: the amyloid cascade hypothesis

Rapid progress in deciphering the biological mechanism of Alzheimer's disease (AD) has arisen from the application of molecular and cell biology to this complex disorder of the limbic and association cortices. In turn, new insights into fundamental aspects of protein biology have resulted from research on the disease. This beneficial interplay between basic and applied cell biology is well illustrated by advances in understanding the genotype-to-phenotype relationships of familial Alzheimer's disease. All four genes definitively linked to inherited forms of the disease to date have been shown to increase the production and/or deposition of amyloid β-protein in the brain. In particular, evidence that the presenilin proteins, mutations in which cause the most aggressive form of inherited AD, lead to altered intramembranous cleavage of the β-amyloid precursor protein by the protease called γ-secretase has spurred progress toward novel therapeutics. The finding that presenilin itself may be the long-sought γ-...

Alzheimer's Disease: Genes, Proteins, and Therapy

We present here both linear regressions and multivariate analyses correlating three global neuropsychological tests with a number of structural and neurochemical measurements performed on a prospective series of 15 patients with Alzheimer's disease and 9 neuropathologically normal subjects. The statistical data show only weak correlations between psychometric indices and plaques and tangles, but the density of neocortical synapses measured by a new immunocytochemical/densitometric technique reveals very powerful correlations with all three psychological assays. Multivariate analysis by stepwise regression produced a model including midfrontal and inferior parietal synapse density, plus inferior parietal plaque counts with a correlation coefficient of 0.96 for Mattis's Dementia Rating Scale. Plaque density contributed only 26% of that strength.

Physical basis of cognitive alterations in Alzheimer's disease: synapse loss is the major correlate of cognitive impairment.

/pdf/a-highly-efficient-low-pressure-uv-rich-detector-with-29ircty16d.pdf

A Highly Efficient Low-Pressure Uv-Rich Detector with Optical Avalanche Recording

The major protein subunit of the amyloid fibril in Alzheimer’s disease is a small molecule of 42 residues (termed A4). It is derived from a larger precursor (PreA4), the gene for which is located on chromosome 21, in close proximity to the region involved in Down’s syndrome. The predicted structure of PreA4 suggests that it is an integral membrane glycoprotein. Knowledge of the mechanisms by which PreA4 is degraded to A4 may contribute to a better understanding of the cause of Alzheimer’s disease. Similarly, the amyloid fibril in the unconventional virus diseases is composed of the PrP molecule, which in turn is derived from a neuronal membrane glycoprotein. An understanding of the process by which the PrP molecule is converted into an amyloidogenic molecule may shed some light on the nature of the infectious unit.

The Molecular Basis of Cerebral Amyloidosis in Alzheimer’s Disease and the Unconventional Virus Diseases

Electron paramagnetic resonance study of the photoexcited triplet states of some fluorinated naphthalenes

Using dark rate dependent feedback and quench circuitry, avalanche photodiodes have been stably operated at voltages close to breakdown and above. Exploiting the large amplification in such an operation, time resolutions of 15 ps for 10 8 incident photons have been measured at temperatures around 0°C.

/pdf/picosecond-timing-using-avalanche-photodiodes-operated-near-20zf7cka13.pdf

Picosecond timing using avalanche photodiodes operated near breakdown

We prove and demonstrate here for the example of the large-scale pixel detector of ATLAS that Serial Powering of pixel modules is a viable alternative and that has been devised and implemented for ATLAS pixel modules using dedicated on-chip voltage regulators and modified flex hybrid circuits. The equivalent of a pixel ladder consisting of six serially powered pixel modules with about 0.3 Mpixels has been built and the performance with respect to noise and threshold stability and operation failures has been studied. We believe that Serial Powering in general will be necessary for future large-scale tracking detectors.

/pdf/concept-realization-and-characterization-of-serially-powered-s77c3zwks0.pdf

Peter Fischer

Papers

A Highly Efficient Low-Pressure Uv-Rich Detector with Optical Avalanche Recording

The Molecular Basis of Cerebral Amyloidosis in Alzheimer’s Disease and the Unconventional Virus Diseases

Electron paramagnetic resonance study of the photoexcited triplet states of some fluorinated naphthalenes

Picosecond timing using avalanche photodiodes operated near breakdown

Concept, realization and characterization of serially powered pixel modules (Serial Powering)