Static compression of porous dust aggregates

Context: In protoplanetary disks, dust grains coagulate with each other and grow to form aggregates. As these aggregates grow by coagulation, their filling factor \phi decreases down to \phi << 1. However, comets, the remnants of these early planetesimals, have \phi ~ 0.1. Thus, static compression of porous dust aggregates is important in planetesimal formation. However, the static compression strength has been investigated only for relatively high density aggregates (\phi > 0.1). Aims: We investigate and find the compression strength of highly porous aggregates (\phi << 1). Methods: We perform three dimensional N-body simulations of aggregate compression with a particle-particle interaction model. We introduce a new method of static compression: the periodic boundary condition is adopted and the boundaries move with low speed to get closer. The dust aggregate is compressed uniformly and isotropically by themselves over the periodic boundaries. Results: We empirically derive a formula of the compression strength of highly porous aggregates (\phi << 1). We check the validity of the compression strength formula for wide ranges of numerical parameters, such as the size of initial aggregates, the boundary speed, the normal damping force, and material. We also compare our results to the previous studies of static compression in the relatively high density region (\phi > 0.1) and confirm that our results consistently connect to those in the high density region. The compression strength formula is also derived analytically.Comment: 12 pages, 14 figures, accepted for publication in A&

Opacity of fluffy dust aggregates

Context. Dust grains coagulate to form dust aggregates in protoplanetary disks. Their porosity can be extremely high in the disks. Although disk emission may come from fluffy dust aggregates, the emission has been modeled with compact grains. Aims. We aim to reveal the mass opacity of fluffy aggregates from infrared to millimeter wavelengths with the filling factor ranging from 1 down to $10^{-4}$. Methods. We use Mie calculations with an effective medium theory. The monomers are assumed to be 0.1 ${\rm \mu m}$ sized grains, which is much shorter than the wavelengths that we focus on. Results. We find that the absorption mass opacity of fluffy aggregates are characterized by the product $a\times f$, where $a$ is the dust radius and $f$ is the filling factor, except for the interference structure. The scattering mass opacity is also characterized by $af$ at short wavelengths while it is higher in more fluffy aggregates at long wavelengths. We also derive the analytic formula of the mass opacity and find that it reproduces the Mie calculations. We also calculate the expected difference of the emission between compact and fluffy aggregates in protoplanetary disks with a simple dust growth and drift model. We find that compact grains and fluffy aggregates can be distinguished by the radial distribution of the opacity index $\beta$. The previous observation of the radial distribution of $\beta$ is consistent with the fluffy case, but more observations are required to distinguish between fluffy or compact. In addition, we find that the scattered light would be another way to distinguish between compact grains and fluffy aggregates.Comment: 16 pages, 17 figures, published in A&A, 568, A4

Nightmare-Enacting Behavior Responding to Zonisamide in Early Parkinson's Disease

Recently, zonisamide (ZNS) has been approved as a new adjunctive therapy for motor complications of Parkinson's disease (PD). More recently, ZNS was reported to be effective for the management of impulse control behavior in PD, suggesting potential effects on non-motor PD symptoms. Dream enactment associated with aggressive, violent behavior can carry a serious risk of injury to patients, as well as to spouses or caretakers. This report describes a patient with PD who had vivid nightmares and dream-enacting behavior that resolved after treatment with ZNS. The present case raises the question whether ZNS might potentially be effective for the management of vivid nightmares or dream-enacting behavior

Effect of dust size and structure on scattered light images of protoplanetary discs

We study scattered light properties of protoplanetary discs at near-infrared wavelengths for various dust size and structure by performing radiative transfer simulations. We show that different dust structures might be probed by measuring disk polarisation fraction as long as the dust radius is larger than the wavelength. When the radius is larger than the wavelength, disc scattered light will be highly polarised for highly porous dust aggregates, whereas more compact dust structure tends to show low polarisation fraction. Next, roles of monomer radius and fractal dimension for scattered light colours are studied. We find that, outside the Rayleigh regime, as fractal dimension or monomer radius increases, colours of the effective albedo at near-infrared wavelengths vary from blue to red. Our results imply that discs showing grey or slightly blue colours and high polarisation fraction in near-infrared wavelengths might be explained by the presence of large porous aggregates containing sub-microns sized monomers.Comment: Accepted for publication in MNRAS, 18 pages, 19 figure

A Randomized Controlled Trial of Short-term Toe Resistance Training to Improve Toe Pinch Force in Patients with Type 2 Diabetes

Resistance training is effective against type 2 diabetes (T2DM), but the effect of resistance training on toe pinch force (TPF) is unknown. Here we investigated the effect of short-term toe resistance training on TPF in patients with T2DM, in a prospective, parallel-group, single-blind, randomized controlled trial. Twelve patients with T2DM who were hospitalized to improve glycemic control were enrolled. The patients were randomly allocated to the intervention (n=6) and control (n=6) groups. The intervention group performed traditional aerobic exercise and 4 newly developed toe-resistance training exercises. The control group performed aerobic exercise only. After 2 weeks of the exercise intervention program, we evaluated anthropometric parameters, clinical parameters, motor function, and muscle parameters in each patient. After the exercise intervention program, the TPF and toe muscle quality, isometric knee extension force, and knee muscle quality were significantly higher in the intervention group compared to the control group. Two weeks of toe-resistance training significantly increased the TPF in the T2DM patients. Toe resistance training is thus recommended in clinical practice for patients with T2DM

Minimum Supersymmetric Standard Model on the Noncommutative Geometry

We have obtained the supersymmetric extension of spectral triple which specify a noncommutative geometry(NCG). We assume that the functional space H constitutes of wave functions of matter fields and their superpartners included in the minimum supersymmetric standard model(MSSM). We introduce the internal fluctuations to the Dirac operator on the manifold as well as on the finite space by elements of the algebra A in the triple. So, we obtain not only the vector supermultiplets which meditate SU(3)xSU(2)xU(1)_Y gauge degrees of freedom but also Higgs supermultiplets which appear in MSSM on the same standpoint. Accoding to the supersymmetric version of the spectral action principle, we calculate the square of the fluctuated total Dirac operator and verify that the Seeley-DeWitt coeffients give the correct action of MSSM. We also verify that the relation between coupling constants of $SU(3)$,$SU(2)$ and $U(1)_Y$ is same as that of SU(5) unification theory

Supersymmetric Yang-Mills Theory on the Noncommutative Geometry

Recently, we found the supersymmetric counterpart of the spectral triple. When we restrict the representation space to the fermionic functions of matter fields, the counterpart which we name "the triple" reduces to the original spectral triple which defines noncommutative geometry. We see that the fluctuation to the supersymmetric Dirac operator induced by algebra in the triple generates vector supermultiplet which mediates gauge interaction. Following the supersymmetric version of spectral action principle, we calculate the heat kernel expansion of the square of fluctuated Dirac operator and obtain the correct supersymmetric Yang-Mills action with U(N) gauge symmetry.Comment: arXiv admin note: text overlap with arXiv:1201.344