The Simons Observatory: Cryogenic half wave plate rotation mechanism for the small aperture telescopes

We present the requirements, design, and evaluation of the cryogenic continuously rotating half-wave plate (CHWP) for the Simons Observatory (SO). SO is a cosmic microwave background polarization experiment at Parque Astronómico de Atacama in northern Chile that covers a wide range of angular scales using both small (⌀0.42 m) and large (⌀6 m) aperture telescopes. In particular, the small aperture telescopes (SATs) focus on large angular scales for primordial B-mode polarization. To this end, the SATs employ a CHWP to modulate the polarization of the incident light at 8 Hz, suppressing atmospheric 1/f noise and mitigating systematic uncertainties that would otherwise arise due to the differential response of detectors sensitive to orthogonal polarizations. The CHWP consists of a 505 mm diameter achromatic sapphire HWP and a cryogenic rotation mechanism, both of which are cooled down to ∼50 K to reduce detector thermal loading. Under normal operation, the HWP is suspended by a superconducting magnetic bearing and rotates with a constant 2 Hz frequency, controlled by an electromagnetic synchronous motor. We find that the number of superconductors and the number of magnets that make up the superconducting magnetic bearing are important design parameters, especially for the rotation mechanism's vibration performance. The rotation angle is detected through an angular encoder with a noise level of 0.07 μrad s. During a cooldown process, the rotor is held in place by a grip-and-release mechanism that serves as both an alignment device and a thermal path. In this paper, we provide an overview of the SO SAT CHWP: its requirements, hardware design, and laboratory performance.

GA-guided mD-VcMD: A genetic-algorithm-guided method for multi-dimensional virtual-system coupled molecular dynamics

We introduced a conformational sampling method in an earlier report: The multi-dimensional virtual-system coupled molecular dynamics (mD-VcMD) enhances conformational sampling of a biomolecular system by computer simulations. Herein, new sampling method, a subzone-based mD-VcMD, is presented as an extension of mD-VcMD. Then, the subzone-based method is extended further using a genetic algorithm (GA) named the GA-guided mD-VcMD. In these methods, iterative simulation runs are performed to increase the sampled region gradually. The new methods have the following benefits: (1) They are free from a production run: i.e., all snapshots from all iterations are useful for analyses. (2) They are free from fine tuning of a weight function (probability distribution function or potential of mean force). (3) A canonical ensemble (i.e., a thermally equilibrated ensemble) is generated from a simple procedure. A thermodynamic weight is assigned to each snapshot. (4) Selective sampling can be performed for particularly addressing a poorly sampled region without breaking the proportion of the canonical ensemble if the poorly sampled conformational region emerges in sampling. By applying the methods to a simple system that involves an energy barrier between potential-energy minima, we demonstrated that the new methods have considerably higher sampling efficiency than the original mD-VcMD does.

A cryogenic continuously rotating half-wave plate mechanism for the POLARBEAR-2b cosmic microwave background receiver

We present the design and laboratory evaluation of a cryogenic continuously rotating half-wave plate (CHWP) for the POLARBEAR-2b (PB-2b) cosmic microwave background receiver, the second installment of the Simons Array. PB-2b will observe at 5200 m elevation in the Atacama Desert of Chile in two frequency bands centered at 90 GHz and 150 GHz. In order to suppress atmospheric 1/f noise and mitigate systematic effects that arise when differencing orthogonal detectors, PB-2b modulates linear sky polarization using a CHWP rotating at 2 Hz. The CHWP has a 440 mm clear aperture diameter and is cooled to ≈50 K in the PB-2b receiver cryostat. It consists of a low-friction superconducting magnetic bearing and a low-torque synchronous electromagnetic motor, which together dissipate <2 W. During cooldown, a grip-and-release mechanism centers the rotor to <0.5 mm, and during continuous rotation, an incremental optical encoder measures the rotor angle with a noise level of 0.1 μrad/Hz. We discuss the experimental requirements for the PB-2b CHWP, the designs of its various subsystems, and the results of its evaluation in the laboratory. The presented CHWP has been deployed to Chile and is expected to see first light on PB-2b in 2020 or 2021.

Molecular Interaction Mechanism of a 14-3-3 Protein with a Phosphorylated Peptide Elucidated by Enhanced Conformational Sampling

Enhanced conformational sampling, a genetic-algorithm-guided multidimensional virtual-system coupled molecular dynamics, can provide equilibrated conformational distributions of a receptor protein and a flexible ligand at room temperature. The distributions provide not only the most stable but also semistable complex structures and propose a ligand-receptor binding process. This method was applied to a system consisting of a receptor protein, 14-3-3ε, and a flexible peptide, phosphorylated myeloid leukemia factor 1 (pMLF1). The results present comprehensive binding pathways of pMLF1 to 14-3-3ε. We identified four thermodynamically stable clusters of MLF1 on the 14-3-3ε surface and free-energy barriers among some clusters. The most stable cluster includes two high-density spots connected by a narrow corridor. When pMLF1 passes the corridor, a salt-bridge relay (switching) related to the phosphorylated residue of pMLF1 occurs. Conformations in one high-density spot are similar to the experimentally determined complex structure. Three-dimensional distributions of residues in the intermolecular interface rationally explain the binding constant changes resulting from the alanine mutation experiment for the residues. We also performed a simulation of nonphosphorylated peptide and 14-3-3ε, which demonstrated that the complex structure was unstable, suggesting that phosphorylation of the peptide is crucially important for binding to 14-3-3ε.

Internal Delensing of Cosmic Microwave Background Polarization B-Modes with the POLARBEAR Experiment

Using only cosmic microwave background polarization data from the polarbear experiment, we measure B-mode polarization delensing on subdegree scales at more than 5σ significance. We achieve a 14% B-mode power variance reduction, the highest to date for internal delensing, and improve this result to 22% by applying for the first time an iterative maximum a posteriori delensing method. Our analysis demonstrates the capability of internal delensing as a means of improving constraints on inflationary models, paving the way for the optimal analysis of next-generation primordial B-mode experiments.

Hydrogen bond donors and acceptors are generally depolarized in α-helices as revealed by a molecular tailoring approach

Hydrogen‐bond (H‐bond) interaction energies in α‐helices of short alanine peptides were systematically examined by precise density functional theory calculations, followed by a molecular tailoring approach. The contribution of each H‐bond interaction in α‐helices was estimated in detail from the entire conformation energies, and the results were compared with those in the minimal H‐bond models, in which only H‐bond donors and acceptors exist with the capping methyl groups. The former interaction energies were always significantly weaker than the latter energies, when the same geometries of the H‐bond donors and acceptors were applied. The chemical origin of this phenomenon was investigated by analyzing the differences among the electronic structures of the local peptide backbones of the α‐helices and those of the minimal H‐bond models. Consequently, we found that the reduced H‐bond energy originated from the depolarizations of both the H‐bond donor and acceptor groups, due to the repulsive interactions with the neighboring polar peptide groups in the α‐helix backbone. The classical force fields provide similar H‐bond energies to those in the minimal H‐bond models, which ignore the current depolarization effect, and thus they overestimate the actual H‐bond energies in α‐helices. © 2019 The Authors. Journal of Computational Chemistry published by Wiley Periodicals, Inc.

Systematic effects from an ambient-temperature, continuously rotating half-wave plate

We present an evaluation of systematic effects associated with a continuously rotating, ambient-temperature half-wave plate (HWP) based on two seasons of data from the Atacama B-Mode Search (ABS) experiment located in the Atacama Desert of Chile. The ABS experiment is a microwave telescope sensitive at 145 GHz. Here we present our in-field evaluation of celestial (Cosmic Microwave Background (CMB) plus galactic foreground) temperature-to-polarization leakage. We decompose the leakage into scalar, dipole, and quadrupole leakage terms. We report a scalar leakage of ∼0.01%, consistent with model expectations and an order of magnitude smaller than other CMB experiments have been reported. No significant dipole or quadrupole terms are detected; we constrain each to be <0.07% (95% confidence), limited by statistical uncertainty in our measurement. Dipole and quadrupole leakage at this level lead to systematic error on r ≲ 0.01 before any mitigation due to scan cross-linking or boresight rotation. The measured scalar leakage and the theoretical level of dipole and quadrupole leakage produce systematic error of r < 0.001 for the ABS survey and focal-plane layout before any data correction such as so-called deprojection. This demonstrates that ABS achieves significant beam systematic error mitigation from its HWP and shows the promise of continuously rotating HWPs for future experiments.

Density functional study of molecular interactions in secondary structures of proteins

Proteins play diverse and vital roles in biology, which are dominated by their three-dimensional structures. The three-dimensional structure of a protein determines its functions and chemical properties. Protein secondary structures, including α-helices and β-sheets, are key components of the protein architecture. Molecular interactions, in particular hydrogen bonds, play significant roles in the formation of protein secondary structures. Precise and quantitative estimations of these interactions are required to understand the principles underlying the formation of three-dimensional protein structures. In the present study, we have investigated the molecular interactions in α-helices and β-sheets, using ab initio wave function-based methods, the Hartree-Fock method (HF) and the second-order Møller-Plesset perturbation theory (MP2), density functional theory, and molecular mechanics. The characteristic interactions essential for forming the secondary structures are discussed quantitatively.

Modulation of cosmic microwave background polarization with a warm rapidly rotating half-wave plate on the Atacama B-Mode Search instrument

We evaluate the modulation of cosmic microwave background polarization using a rapidly rotating, half-wave plate (HWP) on the Atacama B-Mode Search. After demodulating the time-ordered-data (TOD), we find a significant reduction of atmospheric fluctuations. The demodulated TOD is stable on time scales of 500-1000 s, corresponding to frequencies of 1-2 mHz. This facilitates recovery of cosmological information at large angular scales, which are typically available only from balloon-borne or satellite experiments. This technique also achieves a sensitive measurement of celestial polarization without differencing the TOD of paired detectors sensitive to two orthogonal linear polarizations. This is the first demonstration of the ability to remove atmospheric contamination at these levels from a ground-based platform using a rapidly rotating HWP.

Impaired tight junctions obstruct stratum corneum formation by altering polar lipid and profilaggrin processing

BACKGROUND

The stratum corneum (SC) is a well-known structure responsible for the cutaneous barrier. Tight junctions (TJs) function as a paracellular barrier beneath the SC and are involved in the cutaneous barrier. It remains unclear how TJs are involved in the cutaneous barrier.

OBJECTIVE

In order to clarify the role of TJs in the cutaneous barrier, we investigated skin equivalent models with disrupted TJ barriers focusing on the SC.

METHODS

Skin equivalents with disrupted TJ barriers were established using GST-C-CPE, a peptide with specific inhibitory action against specific claudins. The changes of the SC barrier in the skin equivalents with disrupted TJ barriers were investigated and compared with control skin equivalents.

RESULTS

An outside-to-inside skin barrier assay revealed a defective SC barrier in skin equivalents with disrupted TJ barriers. A detailed examination of the SC revealed an increase in the pH of the SC in the skin equivalent with disrupted TJ barriers. An electron microscopy showed the failure of lamellar structures to mature and the failure of keratohyalin granules to degrade in the skin equivalents with disrupted TJ barriers. A thin layer chromatography analysis showed an increase in polar lipids and a decrease in non-polar lipids. A western blot analysis showed an increase in filaggrin dimer and trimer and a decrease in filaggrin monomer.

CONCLUSION

We found that disrupted TJs obstructed the SC formation responsible for the cutaneous barrier. Our study indicates the possibility that impaired TJ barriers affect polar lipids and profilaggrin processing by disturbing the pH condition of the SC.

Characterization of tight junctions and their disruption by UVB in human epidermis and cultured keratinocytes

It has not been confirmed whether tight junctions (TJs) function as a paracellular permeability barrier in adult human skin. To clarify this issue, we performed a TJ permeability assay using human skin obtained from abdominal plastic surgery. Occludin, a marker protein of TJs, was expressed in the granular layer, in which a subcutaneously injected paracellular tracer, Sulfo-NHS-LC-Biotin (556.59 Da), was halted. Incubation with ochratoxin A decreased the expression of claudin-4, an integral membrane protein of TJs, and the diffusion of paracellular tracer was no longer prevented at the TJs. These results demonstrate that human epidermis possesses TJs that function as an intercellular permeability barrier at least against small molecules (∼550 Da). UVB irradiation of human skin xenografts and human skin equivalents (HSEs) resulted in functional deterioration of TJs. Immunocytochemical staining of cultured keratinocytes showed that occludin was localized into dot-like shapes and formed a discontinuous network when exposed to UVB irradiation. Furthermore, UVB irradiation downregulated the active forms of Rac1 and atypical protein kinase C, suggesting that their inactivation caused functional deterioration of TJs. In conclusion, TJs function as a paracellular barrier against small molecules (∼550 Da) in human epidermis and are functionally deteriorated by UVB irradiation.

Measurement of CP asymmetry in a time-dependent Dalitz analysis of B0-->(rhopi)0 and a constraint on the quark mixing matrix angle phi2

We present a measurement of CP asymmetry using a time-dependent Dalitz plot analysis of B0-->pi+pi-pi0 decays based on a 414 fb(-1) data sample containing 449 x 10(6) BB pairs. The data was collected on the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric energy e+ e- collider. Combining our analysis with information on charged B decay modes, we perform a full Dalitz and isospin analysis and obtain a constraint on the CKM angle phi2, 68 degrees < phi2 < 95 degrees as the 68.3% confidence interval for the phi2 solution consistent with the standard model (SM). A large SM-disfavored region also remains.

Observation of direct CP violation in B0 --> pi+pi- decays and model-independent constraints on the quark-mixing angle phi2

We report a new measurement of the time-dependent CP-violating parameters in B(0)-->pi(+)pi(-) decays with 535 x 10(6) BB pairs collected with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider operating at the Upsilon(4S) resonance. We find 1464+/-65 B(0)-->pi(+)pi(-) events and measure the CP-violating parameters S(pipi)=-0.61+/-0.10(stat)+/-0.04(syst) and A(pipi)=+0.55+/-0.08(stat)+/-0.05(syst). We observe large direct CP violation with a significance greater than 5 standard deviations for any S(pipi) value. Using isospin relations, we measure the Cabibbo-Kobayashi-Maskawa quark-mixing matrix angle phi(2)=(97+/-11) degrees for the solution consistent with the standard model and exclude the range 11 degrees <phi(2)<79 degrees at the 95% confidence level.

Observation of time-dependent CP violation in B0 --> eta'K0 decays and improved measurements of CP asymmetries in B0 --> phiK0, KS0KS0KS0 and B0 --> J/psiK0 decays

We present improved measurements of CP-violation parameters in B(0) --> phiK(0), eta(')K(0), KS(0)KS(0)KS(0) decays based on a sample of 535 x 10(6) BB pairs collected at the Upsilon(4S) resonance with the Belle detector at the KEKB energy-asymmetric e(+)e(-) collider. We obtain sin2phi1(eff)=+0.64+/-0.10(stat)+/-0.04(syst) for B(0) --> eta(')K(0), +0.50+/-0.21(stat)+/-0.06(syst) for B(0) --> phiK(0), and +0.30+/-0.32(stat)+/-0.08(syst) for B(0) --> KS(0)KS(0)KS(0) decays. We have observed CP violation in the B(0) --> eta(')K(0) decay with a significance of 5.6 standard deviations. We also perform an improved measurement of CP asymmetries in B(0) --> J/psiK(0) decays and obtain sin2phi1=+0.642+/-0.031(stat)+/-0.017(syst).

Measurement of the branching fraction, polarization, and asymmetry for decays, and determination of the Cabibbo-Kobayashi-Maskawa phase

We have measured the branching fraction , longitudinal polarization fraction f(L), and CP asymmetry coefficients A and S for B(0) --> rho(+) rho(-) decays with the Belle detector at the KEKB e(+) e(-) collider using 253 Fb(-1) of data. We obtain B = [22.8 +/- 3.8(stat)(+2.3)(-2.6)(syst)] x 10(-6), f(L) = 0.941 (+0.034)(-0.040)(stat) +/- 0.030(syst). A = 0.00 +/- 0.30(stat) +/- 0.09(syst) and S = 0.08 +/- 0.09(syst). These values are used to constrain the Cabibbo-Kobayashi-Maskawa phase ; the solution consistent with the standard model is phi(2) = (88 +/- 17) degrees or 59 degrees < phi(2) < 115 degrees at 90% C.L.

Ultrasonic tissue characterization of photodamaged skin by scanning acoustic microscopy

The aim of this study was to ultrasonically characterize photodamaged skin of the elderly at the microscopic level using scanning acoustic microscopy which showed two-dimentional distribution of sound speed in the skin section. We confirmed that the expression level of the elastin gene was increased in the preauricular skin (photodamaged area), compared with postauricular skin (photo-protected area). The expression level of the procollagen gene was also increased in the preauricular skin compared with postauricular skin. The preauricular skin showed higher sound speed in the papillary dermis (Grenz zone). The site of progressive solar elastosis showed a somewhat sound speed velocity than that of the Grenz zone. Immunohistochemical staining showed conserved deposition of collagen in the Grenz zone even in the more photodamaged preauricular skin. These results suggest that fibrosis in the Grenz zone compensates tissue strength with the progress of solar elastosis. The sound speed analysis of skin will provide important information on heterogeneous mechanical changes in the skin during the process of photoaging.

Improved evidence for direct CP violation in B0-->pi+pi- decays and model-independent constraints on phi2

We present a new measurement of the time-dependent CP-violating parameters in B(0)--> pi(+)pi(-) decays with 275 x 10(6) BB pairs collected with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider operating at the Gamma(4S) resonance. We find 666 +/- 43 B(0) --> pi(+)pi(-) events and measure the CP-violating parameters: S(pipi) = -0.67 +/- 0.16(stat) +/- 0.06(syst) and A(pipi) = +0.56 +/- 0.12(stat) +/- 0.06(syst). We find evidence for large direct CP violation with a significance greater than 4 standard deviations for any S(pipi) value. Using isospin relations, we obtain 95.4% confidence intervals for the Cabibbo-Kobayashi-Maskawa quark-mixing matrix angle phi(2) of 0 degree < phiv(2) < 19 degrees and 71 degrees < phi(2) < 180 degrees.

Studies of CP violation in B-->J/PsiK* decays

CP violation in B-->J/PsiK* decays is studied using an angular analysis in a data sample of 253 fb(-1) recorded with the Belle detector at the KEKB e(+)e(-) collider. The flavor separated measurements of the decay amplitudes indicate no evidence for direct CP violation. T-odd CP violation is studied using the asymmetries in triple product correlations, and the results are consistent with the standard model null predictions. The time-dependent angular analysis gives the following values of CP-violating parameters: sin(2phi(1) = 0.24 +/- 0.31 +/- 0.05 and cos(2phi(1)=0.56 +/- 0.79 +/- 0.11.

Measurement of time-dependent CP-violating asymmetries in B0 --> K(s)0K(s)0K(s)0 decay

We present a measurement of CP-violation parameters in the B0 --> K(s)0K(s)0K(s)0 decay based on a sample of 275 x 10(6) BB pairs collected at the upsilon(4S) resonance with the Belle detector at the KEKB energy-asymmetric e+e- collider. One neutral B meson is fully reconstructed in the decay B0 --> K(s)0K(s)0K(s)0, and the flavor of the accompanying B meson is identified from its decay products. CP-violation parameters are obtained from the asymmetry in the distributions of the proper-time interval between the two B decays: S = +1.26 +/- 0.68(stat) +/- 0.20(syst) and [symbol: see text] = +0.54 +/- 0.34(stat) +/- 0.09(syst).

Measurement of the time-dependent CP-violating asymmetry in B(0)-->K(0)(S)pi(0)gamma decays

We present a new measurement of CP-violation parameters in B(0)-->K(0)(S)pi(0)gamma decay based on a sample of 275 x 10(6) BB pairs collected at the Gamma(4S) resonance with the Belle detector at the KEKB energy-asymmetric e(+)e(-) collider. One of the B mesons is fully reconstructed in the B(0)-->K(0)(S)pi(0)gamma decay. The flavor of the accompanying B meson is identified from its decay products. CP-violation parameters are obtained from the asymmetry in the distribution of the proper time intervals between the two B decays. We obtain SK(0)(S)(pi(0)gamma) = -0.58(+0.46)(-0.38)(stat) +/- 0.11(syst) and AK(0)(S)(pi(0)gamma) = +0.03 +/- 0.34(stat) +/- 0.11(syst), for the K(0)(S)pi(0) invariant mass covering the full range up to 1.8 GeV/c2. We also measure the CP-violation parameters for the case B(0)-->K(*0)(-->K(0)(S)pi(0))gamma and obtain S(K(*0)gamma) = -0.79(+0.63)(-0.50)(stat) +/- 0.10(syst) for A(K(*0)gamma) fixed at 0.

Evidence for direct CP violation in B0-->K+pi- decays

We report evidence for direct CP violation in the decay B0-->K+pi(-) with 253 fb(-1) of data collected with the Belle detector at the KEKB e(+)e(-) collider. Using 275x10(6) BB pairs we observe a B-->K+/-pi(-/+) signal with 2140+/-53 events. The measured CP violating asymmetry is A(CP)(K+pi(-))=-0.101+/-0.025(stat)+/-0.005(syst), corresponding to a significance of 3.9sigma including systematics. We also search for CP violation in the decays B+-->K+pi(0) and B+-->pi(+)pi(0). The measured CP violating asymmetries are A(CP)(K+pi(0))=0.04+/-0.05(stat)+/-0.02(syst) and A(CP)(pi(+)pi(0))=-0.02+/-0.10(stat)+/-0.01(syst), corresponding to the intervals -0.05<A(CP)(K+pi(0))<0.13 and -0.18<A(CP)(pi(+)pi(0))<0.14 at 90% confidence level.

Characteristics of the epidermis and stratum corneum of hairless mice with experimentally induced diabetes mellitus

Diabetes mellitus induces many pathophysiologic changes in the skin. Even so, dermatologists still lack an animal model of diabetes that enables the direct evaluation of the various functional properties of the skin. Our group induced two types of an experimental type 1 diabetes model in hairless mice by administering either streptozotocin or alloxan, in order to examine the properties of the stratum corneum and epidermis of these animals. The plasma glucose concentrations of the mice at 3 wk after their i.v. injection were significantly higher than those of control mice (streptozotocin, 3.2-fold; alloxan, 3.7-fold). The stratum corneum water content was significantly reduced in both types of diabetic mice, whereas the transepidermal water loss remained unchanged. The amino acid content with normal epidermal profilaggrin processing was either normal or elevated in the stratum corneum of the streptozotocin-treated mice. In contrast, the stratum corneum triglyceride content in the streptozotocin-treated mice was significantly lower than the control level, even though the levels of ceramides, cholesterols, and fatty acids in the stratum corneum were all higher than the control levels. The streptozotocin-treated group also exhibited decreases in basal cell proliferation and epidermal DNA content linked with an increase in the number of corneocyte layers in the stratum corneum, suggesting that the rates of epidermal and stratum corneum turnover were slower in the streptozotocin-treated animals than in the normal controls. In contrast, there were no remarkable changes in any of the epidermal differentiation marker proteins examined. This finding in diabetic mice, namely, reduction in both the epidermal proliferation and stratum corneum water content without any accompanying impairment in the stratum corneum barrier function, is similar to that found in aged human skin. Our new animal model of diabetes will be useful for the study of diabetic dermopathy as well as the mechanisms of stratum corneum moisturization.