Explore the vast range of titles available.

A broadband two-layer antireflection (AR) coating was developed for use on a sapphire half-wave plate (HWP) and an alumina infrared (IR) filter for cosmic microwave background (CMB) polarimetry. Measuring tiny CMB B-mode signals requires maximizing the number of photons reaching the detectors and minimizing spurious polarization due to reflection with an off-axis incident angle. However, a sapphire HWP and an alumina IR filter have high refractive indices of ≃ 3.1, and an AR coating must be applied to them. Thermally sprayed mullite and Duroid 5880LZ were selected in terms of index and coefficient of thermal expansion for use at cryogenic temperatures. With these materials, the reflectivity was reduced to about 2% at 90/150 GHz and <1% at 220/280 GHz. The design, fabrication, and optical performance evaluation of the AR coatings are described. The coatings were used in a current ground-based CMB experiment called the Simons Array. Also, they could be applied to next-generation CMB experiments, such as the Simons Observatory.

The ability of animals to process dynamic sensory information facilitates foraging in an ever-changing environment. However, molecular and neural mechanisms underlying such ability remain elusive. The ClC anion channels/transporters play a pivotal role in cellular ion homeostasis across all phyla. Here, we find a ClC chloride channel is involved in salt concentration chemotaxis of Caenorhabditis elegans . Genetic screening identified two altered-function mutations of clh-1 that disrupt experience-dependent salt chemotaxis. Using genetically encoded fluorescent sensors, we demonstrate that CLH-1 contributes to regulation of intracellular anion and calcium dynamics of salt-sensing neuron, ASER. The mutant CLH-1 reduced responsiveness of ASER to salt stimuli in terms of both temporal resolution and intensity, which disrupted navigation strategies for approaching preferred salt concentrations. Furthermore, other ClC genes appeared to act redundantly in salt chemotaxis. These findings provide insights into the regulatory mechanism of neuronal responsivity by ClCs that contribute to modulation of navigation behavior.

The glycoproteins of yeast contain a large outer chain on N-linked oligosaccharides; therefore, yeast is not suitable for producing therapeutic glycoproteins for human use. Using a deletion mutant strain of α1,6-mannosyltransferase (och1Δ), we previously produced humanized N-glycans in fission yeast; however, the Schizosaccharomyces pombe och1Δ cells displayed a growth delay even during vegetative growth, resulting in reduced productivity of heterologous proteins. To overcome this problem, here we performed a genome-wide screen for genes that would suppress the growth defect of temperature-sensitive och1Δ cells. Using a genomic library coupled with screening of 18,000 transformants, we identified two genes (pwp1+, SPBC1E8.05), both encoding GPI-anchored proteins, that increased the growth rate of och1Δ cells, lacking the outer chain. We further showed that a high copy number of the genes was needed to improve the growth rate. Mutational analysis of Pwp1p revealed that the GPI-anchored region of Pwp1p is important in attenuating the growth defect. Analysis of disruptants of pwp1+ and SPBC1E8.05 showed that neither gene was essential for cell viability; however, both mutants were sensitive β-glucanase, suggesting that Pwp1p and the protein encoded by SPBC1E8.05 non-enzymatically support β-glucan on the cell-surface of S. pombe. Collectively, our work not only sheds light on the functional relationships between GPI-anchored proteins and N-linked oligosaccharides of glycoproteins in S. pombe, but also supports the application of S. pombe to the production of human glycoprotein.Key points• We screened for genes that suppress the growth defect of fission yeast och1Δ cells.• Appropriate expression of GPI-anchored proteins alleviates the growth delay of och1Δ cells.• The GPI-anchor domain of Pwp1p is important for suppressing the growth defect of och1Δ cells.

The Simons Observatory (SO) is a cosmic microwave background survey experiment that includes small-aperture telescopes (SATs) observing from an altitude of 5200 m in the Atacama Desert in Chile. The SO SATs will cover six spectral bands between 27 and 280 GHz to search for primordial B-modes to a sensitivity of σ(r) = 0.002, with quantified systematic errors well below this value. Each SAT is a self-contained cryogenic telescope with a 35° field of view, 42 cm diameter optical aperture, 40 K half-wave plate, 1 K refractive optics, and <0.1 K focal plane that holds >12,000 transition edge sensor detectors. We describe the nominal design of the SATs and present details about the integration and testing for one operating at 93 and 145 GHz.

Background and Aims Genetic alterations in specific genes are critical events in carcinogenesis and hepatocellular carcinoma (HCC) progression. However, the genetic alterations responsible for HCC development, progression, and survival are unclear. Methods We investigated the essential difference in genetic alterations between HCC and adjacent non-HCC tissues using next-generation sequencing technology. Results We found recurrent mutations in several genes such as telomerase reverse transcriptase ( TERT ; 65 % of the total 104 HCCs), TP53 (38 %), CTNNB1 (30 %), AXIN1 (2 %), PTEN (2 %), and CDKN2A (2 %). TERT promoter mutations were associated with older age ( p  = 0.005), presence of hepatitis C virus (HCV) infection ( p  = 0.003), and absence of hepatitis B virus (HBV) infection ( p  < 0.0001). In hepatitis B surface antigen (HBs Ag)-positive HCC without TERT promoter mutations, HBV integration into TERT locus was found in 47 % patients and was mutually exclusive to TERT promoter mutations. Most (89 %) HBV integrants were in the HBx region. TP53 mutations were associated with HBV infection ( p  = 0.0001) and absence of HCV infection ( p  = 0.002). CTNNB1 mutations were associated with absence of HBV infection ( p  = 0.010). Moreover, TERT promoter mutation was significantly associated with shorter disease-free survival ( p  = 0.005) and poor overall survival ( p  = 0.024). Conclusions Gene alterations in TERT promoter, TP53 , CTNNB1 , and HBV integration were closely associated with HCC development, and mutations in TERT promoter are related to poor prognosis. These results are useful for understanding the underlying mechanism of hepatocarcinogenesis, diagnosis, and predicting outcomes of patients with HCC.

The Simons Observatory (SO) experiment is a cosmic microwave background (CMB) experiment located in the Atacama Desert, Chile. The SO’s small aperture telescopes (SATs) consist of three telescopes designed for precise CMB polarimetry at large angular scales. Each SAT uses a cryogenic rotating half-wave plate (HWP) as a polarization modulator to mitigate atmospheric 1/ f noise and other systematics. To realize efficient polarization modulation over the observation bands, we fabricated an achromatic HWP (AHWP) consisting of three sapphire plates with anti-reflection coatings. The AHWP is designed to have broadband modulation efficiency and transmittance. This paper reports on the design and the preliminary characterization of the AHWPs for SATs.

Graphene has been actively investigated as an electronic material owing to many excellent physical properties, such as high charge mobility and quantum Hall effect, due to the characteristics of a linear band structure and an ideal two-dimensional electron system. However, the correlations between the transport characteristics and the spin states of charge carriers or atomic vacancies in graphene have not yet been fully elucidated. Here, we show the spin states of single-layer graphene to clarify the correlations using electron spin resonance (ESR) spectroscopy as a function of accumulated charge density using transistor structures. Two different electrically induced ESR signals were observed. One is originated from a Fermi-degenerate two-dimensional electron system, demonstrating the first observation of electrically induced Pauli paramagnetism from a microscopic viewpoint, showing a clear contrast to no ESR observation of Pauli paramagnetism in carbon nanotubes (CNTs) due to a one-dimensional electron system. The other is originated from the electrically induced ambipolar spin vanishments due to atomic vacancies in graphene, showing a universal phenomenon for carbon materials including CNTs. The degenerate electron system with the ambipolar spin vanishments would contribute to high charge mobility due to the decrease in spin scatterings in graphene.

We study the relationship between the levitation gap change and losses in a superconducting magnetic bearing (SMB) system. We develop a polarization modulator bearing for a cosmic microwave background (CMB) polarization experiment. The heat generated by the polarization modulator needs to be kept very low. Therefore, it is essential to model the effect of the levitation gap change of a rotor due to gravity on the rotational loss. We have constructed a prototype small experimental platform of an axial-flux SMB with an array of high-temperature superconductors, YBCO, and a permanent magnet ring. In this system, the weight of the rotor can be set. We measured the effect of the change in the levitation gap of the rotor due to gravity on the loss. When the levitation force was 5.5 N and 16.0 N, the losses generated in the rotor were 9.1 × 10 −3 W and 1.6 × 10 −2 W, respectively. It was confirmed that the loss increases with the increase in the levitation force of the SMB.

We report the development of a large-diameter superconducting magnetic bearing (SMB) used in a continuously rotating cryogenic half-wave plate (HWP) polarization modulator for cosmic microwave background (CMB) polarization experiments. A precise measurement of the CMB polarization will place tighter constrains on cosmic inflation, describing the rapid expansion of the early universe. The polarization modulator is a critical instrument for suppressing 1/f contamination, which is mainly caused by atmospheric noise, and for mitigating systematic uncertainties that arise when differencing orthogonal polarization detectors. To ensure a sufficient field of view and to reduce thermal emission, the polarization modulator must have a clear-aperture diameter of > 500 mm and must operate at cryogenic temperatures. We constructed a superconducting magnetic bearing (SMB) with an inner diameter of 550 mm, which is the largest used in any CMB polarization experiment to date. We tested the friction and stiffness of the bearing at liquid nitrogen temperatures. The measured total loss is 0.4 W and the spring constant is >105 N/m, which satisfies typical experimental requirements. Furthermore, we performed a performance test by changing the number of disk-shaped YBCO tiles, and then confirmed that the SMB performance was proportional to the YBCO volume.

We present the design and the performance of a contact-less cryogenic rotation mechanism used in cosmic microwave background (CMB) experiments. A precise measurement of the CMB polarization is possible to verify the cosmic inflation theory that describes the very beginning (10−38 seconds) of the early universe. The polarization modulator, that rotates a half wave plate continuously at the aperture of the telescope, is one of the key instruments in the experiments. In order to reduce noise and systematic uncertainties, the polarization modulator is required a stable rotation with minimal heat dissipation in a cryogenic environment less than 20 K. Thus, we adopted the rotation mechanism that combines completely contact-less bearing and motor, a superconducting magnetic bearing, and a hollow bore synchronous motor. The heat dissipation and the load torque due to the friction can be minimized by avoiding physical contacts. We constructed the prototype of the rotation mechanism and carried out mechanical and thermal performance tests. A continuous rotation test in cryogenic temperature is performed, and it is confirmed that the rotation stability is less than 1% with the rotation frequency between 0.5 Hz and 3.0 Hz. We also conducted a thermal performance test, and obtained the heat dissipation at the rotor of 9.0 mW. We discussed the reduction of heat dissipation using a developed magnetic circuit with improved magnetic field uniformity.