Robust inference with GhostKnockoffs in genome-wide association studies

Genome-wide association studies (GWASs) have been extensively adopted to depict the underlying genetic architecture of complex diseases. Motivated by GWASs' limitations in identifying small effect loci to understand complex traits' polygenicity and fine-mapping putative causal variants from proxy ones, we propose a knockoff-based method which only requires summary statistics from GWASs and demonstrate its validity in the presence of relatedness. We show that GhostKnockoffs inference is robust to its input Z-scores as long as they are from valid marginal association tests and their correlations are consistent with the correlations among the corresponding genetic variants. The property generalizes GhostKnockoffs to other GWASs settings, such as the meta-analysis of multiple overlapping studies and studies based on association test statistics deviated from score tests. We demonstrate GhostKnockoffs' performance using empirical simulation and a meta-analysis of nine European ancestral genome-wide association studies and whole exome/genome sequencing studies. Both results demonstrate that GhostKnockoffs identify more putative causal variants with weak genotype-phenotype associations that are missed by conventional GWASs

Powder blasting for three-dimensional microstructuring of glass

We report on powder blasting as a promising technology for the three-dimensional structuring of brittle materials. We investigate the basic parameters of this process, which is based on the erosion of a masked substrate by a high-velocity eroding powder beam, using glass substrates. We study the effect of various parameters on the etching rate, like the powder velocity and the mask feature size, which induces geometrical effects to the erosion process. We introduce oblique powder blasting and investigate, in particular, sidewall effects of the micropatterned structures. A few examples of devices micromachined by powder blasting are also presented. Keywords: Sand blasting; Powder blasting; Microfabrication; Erosion; Etchin

Development of a Novel Printed Circuit Board Technology for Inductive Device Applications

This paper describes the fabrication and characterisation of 2-dimensional inductive devices integrated inside printed circuit boards . PCB and flex-foils. These devices basically are composed of three layers of which the outer layers bear the printed coil patterns and the inner layer is a high permeability ferromagnetic sheet core. Both magnetic metal and copper layers are patterned using standard lithographic techniques. Electroplated interconnections between the outer layers complete the windings. We have fabricated both transformers and fluxgate magnetic field sensing devices with a thickness of 200 mm for the flex-foil devices and 600 mm for the PCB-based devices. Lateral dimensions are approximately 1 cm. We realise relatively high inductances of 1–10 mH at a frequency of 1 kHz for the transformers and a magnetic field detection limit of 43 mT at 20 kHz for the fluxgate devices

A Fast and Robust Strategy to Remove Variant-Level Artifacts in Alzheimer Disease Sequencing Project Data

Exome sequencing (ES) and genome sequencing (GS) are expected to be critical to further elucidate the missing genetic heritability of Alzheimer disease (AD) risk by identifying rare coding and/or noncoding variants that contribute to AD pathogenesis. In the United States, the Alzheimer Disease Sequencing Project (ADSP) has taken a leading role in sequencing AD-related samples at scale, with the resultant data being made publicly available to researchers to generate new insights into the genetic etiology of AD. To achieve sufficient power, the ADSP has adapted a study design where subsets of larger AD cohorts are collected and sequenced across multiple centers, using a variety of sequencing platforms. This approach may lead to variable variant quality across sequencing centers and/or platforms. In this study, we sought to implement and evaluate filters that can be applied fast to robustly remove variant-level artifacts in the ADSP data

A New Hybrid Technology for Planar Fluxgate Sensor Fabrication

We have adapted a new printed circuit board (PCB) technology to the fabrication of ultraflat and sensitive fluxgate magnetic field sensors. The two outer layers of the PCB stack compose the electrical windings of fluxgates, while the inner layer is made of a micro-patterned amorphous magnetic ribbon with extremely high relative magnetic permeability (µ_r=100 000). Two basic configurations were considered: one based on a toroidal magnetic core and the other on a rectangular core with and without an air gap. The field response and sensitivity of the fluxgate devices have been studied as a function of the gap length, the excitation current, and excitation frequency. Compared to fluxgate sensors of similar size, a relatively high sensitivity of 60 V/T was found at 30 kHz for a five-winding detection coil wound around a rectangular E-shaped magnetic core. This high performance is primarily attributable to the high-permeability magnetic core. The results clearly show the potential of this fluxgate device for application as a magnetic sensor

Printed circuit board integrated fluxgate sensor

We have developed a cheap and simple trilayer printed circuit board (PCB)-based technology, adapted for the fabrication of fluxgate magnetic sensors. The two outer layers of the PCB stack comprise the electrical windings of the fluxgate, while the inner layer is made of patterned amorphous magnetic core with extremely high relative magnetic permeability (µr100,000). The output voltage and the sensitivity of the fluxgate devices have been studied as a function of the external field and of the geometry of the magnetic core. We have found a relatively high sensitivity of 18 V/T at an excitation current frequency of 10 kHz. The results obtained clearly show the potential of this miniaturised fluxgate device for application as a magnetic field sensor. Keywords: Fluxgate sensor; Sensitivity; High permeability; Compass; Vitrovac®; Printed circuit board (PCB

The introduction of powder blasting for sensor and microsystem applications

We introduce powder blasting using a pressurised nozzle and a metallic mask as a new promising technology for microsystem fabrication. We study basic parameters of this powder blasting erosion process as well as mask-geometry effects on the erosion rate. We demonstrate the application potential of this technique in three important fields of microsystems research: (i) the realisation of microfluidic chips for biochemical separations, (ii) the micropatterning of composite hard magnetic layers for mechatronic and magnetic sensor applications, and (iii) the realisation of inertial sensors in glass. We present for the first time a mechanical and electrical characterisation of powder-blasted accelerometer devices. Keywords: Powder blasting; Microfabrication; Accelerometer; Erosio