Time dependence studies on giant magnetoresistive Co/Cu multilayers

Time dependence studies consisting of applying current steps at fixed applied fields have been carried out on bilinear and biquadratic giant magnetoresistive (GMR) Co/Cu multilayers in a temperature controlled environment. It has been shown that the voltage responses to current steps of these aged multilayers are greater in magnitude before field cycling compared to those made after field cycling. Normalized voltage measurements for some samples suggest a magnetic viscosity effect due to a current step at zero-field is present and before field cycling. The effect is reduced after field cycling. This behavior suggests that the effect being seen is purely magnetic in origin, as only the field is being varied. A ln( ) type function has been curve fitted to the zero field voltage response to a current step before field cycling. Voltage measurements made on the Co/Cu films at different field values show that as the applied fields are increased the voltage response has a reduced ln(t) character

Mid-infrared luminous quasars in the GOODS–Herschel fields: a large population of heavily obscured, Compton-thick quasars at z ≈ 2

We present the infrared (IR) and X-ray properties of a sample of 33 mid-IR luminous quasars (νL6 μm ≥ 6 × 1044 erg s−1) at redshift z ≈ 1–3, identified through detailed spectral energy distribution analyses of distant star-forming galaxies, using the deepest IR data from Spitzer and Herschel in the GOODS–Herschel fields. The aim is to constrain the fraction of obscured, and Compton-thick (CT, NH > 1.5 × 1024 cm−2) quasars at the peak era of nuclear and star formation activities. Despite being very bright in the mid-IR band, ≈30 per cent of these quasars are not detected in the extremely deep 2 and 4 Ms Chandra X-ray data available in these fields. X-ray spectral analysis of the detected sources reveals that the majority (≈67 per cent) are obscured by column densities NH > 1022 cm−2; this fraction reaches ≈80 per cent when including the X-ray-undetected sources (9 out of 33), which are likely to be the most heavily obscured, CT quasars. We constrain the fraction of CT quasars in our sample to be ≈24–48 per cent, and their space density to be Φ = (6.7 ± 2.2) × 10−6 Mpc−3. From the investigation of the quasar host galaxies in terms of star formation rates (SFRs) and morphological distortions, as a sign of galaxy mergers/interactions, we do not find any direct relation between SFRs and quasar luminosity or X-ray obscuration. On the other hand, there is tentative evidence that the most heavily obscured quasars have, on average, more disturbed morphologies than the unobscured/moderately obscured quasar hosts, which preferentially live in undisturbed systems. However, the fraction of quasars with disturbed morphology amongst the whole sample is ≈40 per cent, suggesting that galaxy mergers are not the main fuelling mechanism of quasars at z ≈ 2

Micromagnetic disorder in antiparallel biased spin valves

The reorientation of antiferromagnetically coupled Co layers comprising the pinned layers of an antiparallel biased spin valve is reported. Initially, the lower Co layer is saturated in the growth field in the deposition chamber, but it reorients as the upper Co layer grows to be thicker than the lower one. We have investigated the nature of this reorientation by ex situ transport measurements and Lorentz microscopy, and found it highly inhomogeneous, leading to a complex in-plane domain pattern. This results in a reduction of the giant magnetoresistance of the spin valves close to the balance point, where the benefits of the antiparallel biasing are greatest

Collaborative effect of Csnk1a1 haploinsufficiency and mutant p53 in Myc induction can promote leukemic transformation

It is still not fully understood how genetic haploinsufficiency in del(5q) myelodysplastic syndrome (MDS) contributes to malignant transformation of hematopoietic stem cells. We asked how compound haploinsufficiency for Csnk1a1 and Egr1 in the common deleted region on chromosome 5 affects hematopoietic stem cells. Additionally, Trp53 was disrupted as the most frequently comutated gene in del(5q) MDS using CRISPR/Cas9 editing in hematopoietic progenitors of wild-type (WT), Csnk1a1–/+, Egr1–/+, Csnk1a1/Egr1–/+ mice. A transplantable acute leukemia only developed in the Csnk1a1–/+ Trp53–edited recipient. Isolated blasts were indefinitely cultured ex vivo and gave rise to leukemia after transplantation, providing a tool to study disease mechanisms or perform drug screenings. In a small-scale drug screening, the collaborative effect of Csnk1a1 haploinsufficiency and Trp53 sensitized blasts to the CSNK1 inhibitor A51 relative to WT or Csnk1a1 haploinsufficient cells. In vivo, A51 treatment significantly reduced blast counts in Csnk1a1 haploinsufficient/Trp53 acute leukemias and restored hematopoiesis in the bone marrow. Transcriptomics on blasts and their normal counterparts showed that the derived leukemia was driven by MAPK and Myc upregulation downstream of Csnk1a1 haploinsufficiency cooperating with a downregulated p53 axis. A collaborative effect of Csnk1a1 haploinsufficiency and p53 loss on MAPK and Myc upregulation was confirmed on the protein level. Downregulation of Myc protein expression correlated with efficient elimination of blasts in A51 treatment. The “Myc signature” closely resembled the transcriptional profile of patients with del(5q) MDS with TP53 mutation.</p

Facilities management quality systems: An important improvement area

The case study presented illustrates the personnel aspects of facilities management as an interactive function. Aspects of tqm are valuable, but an emphasis on learning organizations - based on learning individuals - has emerged as probably the most productive approach