Control moment gyro optimization study

Control moment gyro optimizatio

Incommensurate Charge and Spin Fluctuations in d-wave Superconductors

We show analytic results for the irreducible charge and spin susceptibilities, $\chi_0 (\omega, {\bf Q})$, where ${\bf Q}$ is the momentum transfer between the nodes in d-wave superconductors. Using the BCS theory and a circular Fermi surface, we find that the singular behavior of the irreducible charge susceptibility leads to the dynamic incommensurate charge collective modes. The peaks in the charge structure factor occur at a set of wave vectors which form an ellipse around ${\bf Q}_{\pi}=(\pi,\pi)$ and ${\bf Q}_0=(0,0)$ in momentum space with momentum dependent spectral weight. It is also found that, due to the non-singular irreducible spin susceptibility, an extremely strong interaction via random phase approximation is required to support the magnetic peaks near ${\bf Q}_{\pi}$. Under certain conditions, the peaks in the magnetic structure factor occur near ${\bf Q}=(\pi,\pi (1 \pm \delta))$ and $(\pi (1 \pm \delta),\pi)$.Comment: 5 pages, 3 figure

Positive impacts of social media at work: job satisfaction, job calling, and Facebook use among co-workers

The number of Facebook users grew rapidly since its conception.Within today’s workplace, employees are increasingly connecting with each other on Facebook for interpersonal reasons.Due to sensational reports by media outlets of inappropriate social media use, many organizations are taking extreme measures about how their employees who utilize Facebook to connect with colleagues.Contrary to the negative assumptions, McAfee [1] states that social media within the workplace can promote positive dynamics. The present study uses McAfee’s argument to examine if a positive connection exists between colleagues who use Facebook to connect with each other. An online survey with questions involving Facebook use with co-workers, job satisfaction, and perceived job calling was completed by employees (N=70) at two high-tech companies in Northern California, USA.Results revealed that job satisfaction is positively correlated with intensity of Facebook use among co-workers. Furthermore, feeling called to one’s line of work was statistically significantly higher for the group of employees who spent the most amount of time interacting on Facebook with their co-workers than the group that spent the least amount of time.These results suggest that companies could begin to explore the positive benefits of social media use within the workplace

Rapid short-pulses of focused ultrasound and microbubbles deliver a range of agent sizes to the brain

Focused ultrasound and microbubbles can non-invasively and locally deliver therapeutics and imaging agents across the blood–brain barrier. Uniform treatment and minimal adverse bioeffects are critical to achieve reliable doses and enable safe routine use of this technique. Towards these aims, we have previously designed a rapid short-pulse ultrasound sequence and used it to deliver a 3 kDa model agent to mouse brains. We observed a homogeneous distribution in delivery and blood–brain barrier closing within 10 min. However, many therapeutics and imaging agents are larger than 3 kDa, such as antibody fragments and antisense oligonucleotides. Here, we evaluate the feasibility of using rapid short-pulses to deliver higher-molecular-weight model agents. 3, 10 and 70 kDa dextrans were successfully delivered to mouse brains, with decreasing doses and more heterogeneous distributions with increasing agent size. Minimal extravasation of endogenous albumin (66.5 kDa) was observed, while immunoglobulin (~ 150 kDa) and PEGylated liposomes (97.9 nm) were not detected. This study indicates that rapid short-pulses are versatile and, at an acoustic pressure of 0.35 MPa, can deliver therapeutics and imaging agents of sizes up to a hydrodynamic diameter between 8 nm (70 kDa dextran) and 11 nm (immunoglobulin). Increasing the acoustic pressure can extend the use of rapid short-pulses to deliver agents beyond this threshold, with little compromise on safety. This study demonstrates the potential for deliveries of higher-molecular-weight therapeutics and imaging agents using rapid short-pulses

Androgenic and Estrogenic Response of Green Mussel Extracts from Singapore’s Coastal Environment Using a Human Cell-Based Bioassay

In the last decade, evidence of endocrine disruption in biota exposed to environmental pollutants has raised serious concern. Human cell-based bioassays have been developed to evaluate induced androgenic and estrogenic activities of chemical compounds. However, bioassays have been sparsely applied to environmental samples. In this study we present data on sex hormone activities in the green mussel, Perna viridis, in Singapore’s coastal waters. P. viridis is a common bioindicator of marine contamination, and this study is a follow-up to an earlier investigation that reported the presence of sex hormone activities in seawater samples from Singapore’s coastal environment. Specimens were collected from eight locations around the Singapore coastline and analyzed for persistent organic pollutants (POPs) and heavy metals. Tissue extracts were then screened for activities on androgen receptors (ARs) and estrogen receptors (ER-α and ER-β) using a reporter gene bio-assay based on a HeLa human cell line. Mussel extracts alone did not exhibit AR activity, but in the presence of the reference androgenic hormone dihydrotestosterone (DHT), activities were up to 340% higher than those observed for DHT alone. Peak activities were observed in locations adjacent to industrial and shipping activities. Estrogenic activities of the mussel extract both alone and in the presence of reference hormone were positive. Correlations were statistically investigated between sex hormone activities, levels of pollutants in the mussel tissues, and various biological parameters (specimen size, sex ratio, lipid and moisture content). Significant correlations exist between AR activities, in the presence of DHT, and total concentration of POPs (r = 0.725, p < 0.05)

Ciliary entry of the kinesin-2 motor KIF17 is regulated by importin-beta2 and RanGTP

The biogenesis, maintenance, and function of primary cilia are controlled through intraflagellar transport (IFT) driven by two kinesin-2 family members, the heterotrimeric KIF3A/KIF3B/KAP complex and the homodimeric KIF17 motor1,2. How these motors and their cargoes gain access to the ciliary compartment is poorly understood. We identify a ciliary localization signal (CLS) in the KIF17 tail domain that is necessary and sufficient for ciliary targeting. Similarities between the CLS and classic nuclear localization signals (NLS) suggests that similar mechanisms regulate nuclear and ciliary import. We hypothesize that ciliary targeting of KIF17 is regulated by a Ran-GTP gradient across the ciliary base. Consistent with this, cytoplasmic expression of GTP-locked Ran(G19V) disrupts the gradient and abolishes ciliary entry of KIF17. Furthermore, KIF17 interacts with importin-β2 in a manner dependent on the CLS and inhibited by Ran-GTP. We propose that Ran plays a global role in regulating cellular compartmentalization by controlling the shuttling of cytoplasmic proteins into nuclear and ciliary compartments

Theory of Tunneling Anomaly in Superconductor above Paramagnetic Limit

We study the tunneling density of states (DoS) in the superconducting systems driven by Zeeman splitting $E_Z$ into the paramagnetic phase. We show that, even though the BCS gap disappears, superconducting fluctuations cause a strong DoS singularity in the vicinity of energies $-E^*$ for electrons polarized along the magnetic field and $E^*$ for the opposite polarization. The position of this singularity E^*=\case{1}{2}(E_Z + \sqrt{E_Z^2- \Delta^2}) (where $\Delta$ is BCS gap at $E_Z=0$) is universal. We found analytically the shape of the DoS for different dimensionality of the system. For ultra-small grains the singularity has the shape of the hard gap, while in higher dimensions it appears as a significant though finite dip. The spin-orbit scattering, and the orbital magnetic field suppress the singularity. Our results are qualitatively consistent with recent experiments in superconducting films.Comment: 29 pages, 17 figures include

Frustrated kinetic energy, the optical sum rule, and the mechanism of superconductivity

The theory that the change of the electronic kinetic energy in a direction perpendicular to the CuO-planes in high-temperature superconductors is a substantial fraction of the condensation energy is examined. It is argued that the consequences of this theory based on a rigorous $c$-axis conductivity sum rule are consistent with recent optical and penetration depth measurements.Comment: 4 pages (RevTeX) and 2 eps figure

Strong magnetoelastic effect on the magnetoelectric phenomena of TbMn2O5

Comparative studies of magnetoelectric susceptibility (??), magnetization (M), and magnetostriction (u) in TbMn2O5 reveal that the increment of M owing to the field-induced Tb3+ spin alignment produces a field-asymmetric line shape in the ??(H) curve, which is conspicuous in a low-temperature incommensurate phase but persistently subsists in the entire ferroelectric phase. Correlations among electric polarization, u, and M2 variation represent linear relationships, unambiguously showing the significant role of Tb magnetoelastic effects on the low-field magnetoelectric phenomena of TbMn2O5. An effective free energy capturing the observed experimental features is also suggested.open3