Design and development of a low temperature, inductance based high frequency ac susceptometer

We report on the development of an induction based low temperature high frequency ac susceptometer capable of measuring at frequencies up to 3.5 MHz and at temperatures between 2 K and 300 K. Careful balancing of the detection coils and calibration have allowed a sample magnetic moment resolution of $5\times10^{-10} Am^2$ at 1 MHz. We will discuss the design and characterization of the susceptometer, and explain the calibration process. We also include some example measurements on the spin ice material CdEr$_2$S$_4$ and iron oxide based nanoparticles to illustrate functionality

The effect of non-Newtonian behavior on contact formation in an external gear pump

In an extrusion process, an external gear pump can be used to control the flow rate of the system. When extruding polymers, the viscosity is quite high, resulting in negligible inertia and thus laminar flow. The external gear pump contains two gears, one driven by a motor and one driven by means of contact with the other gear. In our previous work, the flow of a viscous fluid through an external gear pump was studied using the finite element method. Local mesh refinement was applied based on the respective distance between boundaries. Furthermore, the rotation of both gears was imposed. In this work, the rotation of one gear is imposed, whereas the other gear is freely rotating. However, the minimum distance between the gears is limited to a minimum value. When this value is reached, contact is assumed and also the rotation of second gear is imposed. A reversion of the torque on this gear results in a release of contact. In this manner, a quasi driver/driven situation is created in the numerical simulations. It is observed that contact is released periodically, and thus cannot be assumed present continuously, as is often prescribed. Non-Newtonian material properties, such as shear thinning and the pressure dependence of the density or the viscosity, alter how long contact is released during a tooth rotation

Simulation of a Dripping Faucet

We present a simulation of a dripping faucet system. A new algorithm based on Lagrangian description is introduced. The shape of drop falling from a faucet obtained by the present algorithm agrees quite well with experimental observations. Long-term behavior of the simulation can reproduce period-one, period-two, intermittent and chaotic oscillations widely observed in experiments. Possible routes to chaos are discussed.Comment: 20 pages, 15 figures, J. Phys. Soc. Jpn. (in press

Picture of the low-dimensional structure in chaotic dripping faucets

Chaotic dynamics of the dripping faucet was investigated both experimentally and theoretically. We measured continuous change in drop position and velocity using a high-speed camera. Continuous trajectories of a low-dimensional chaotic attractor were reconstructed from these data, which was not previously obtained but predicted in our fluid dynamic simulation. From the simulation, we further obtained an approximate potential function with only two variables, the drop mass and its position of the center of mass. The potential landscape helps one to understand intuitively how the dripping dynamics can exhibit low-dimensional chaos.Comment: 8 pages, 3 figure

Trends in incidence and costs of injuries to the shoulder, arm and wrist in the Netherlands between 1986 and 2008

Background: Upper extremity injuries account for a large proportion of attendances to the Emergency Department. The aim of this study was to assess population-based trends in the incidence of upper extremity injuries in the Dutch population between 1986 and 2008

T-Cell Receptor γδ Bearing Cells in Normal Human Skin

T-cell antigen receptors (TCR) are divided into common αβ and less common γδ types. In the murine skin, TCR γδ+ cells have been reported to form the great majority of epidermal T lymphocytes. We have examined the relative contribution of TCR αβ+ and TCR γδ+ cells to the T-cell population in normal human skin. Serial sections of freshly frozen skin specimens were acetone fixed, incubated with anti-CD3, βF 1 (anti-TCR αβ, anti-TCR γδ-1 and anti-TCR δ1 (anti-TCR γδ) monoclonal antibodies (MoAb), and stained with a highly sensitive method. Over 90% of the T cells of normal human skin are localized around the postcapillary venules of the dermis, while less than 5% are present within the epidermis. In papillary dermis, TCR γδ+ cells formed on average 7% (anti-TCR γδ-1) or 9% (anti-TCR γ1) of the total number of CD3+ cells, while TCR αβ+ cells constituted up to 80%. In epidermis, these percentages were 18% and 29% for TCR γδ+ cells, and up to 60% for TCR γδ+ cells. It is concluded that there is no preferential immigration or in situ expansion of TCR γδ+T cells in normal human skin, because the relative percentages found for the TCR and TCR αβ+ populations in skin are comparable to those found in lymphoid organs and peripheral blood. However, the percentage of TCR γδ+ cells in epidermis seemed on average higher than in papillary dermis. Therefore, there may still be a difference in migration patterns of TCR γδ+ v TCR γβ+ cells, but this does not result in their preferential localization in human epidermis. The hypothesis that TCR γδ+ T cells have a specialized function in immunosurveillance of epithelia may thus not be valid for human epidermis

Dripping Faucet Dynamics Clarified by an Improved Mass-Spring Model

An improved mass-spring model for a dripping faucet is presented. The model is constructed based on the numerical results which we recently obtained from fluid dynamical calculations. Both the fluid dynamical calculations and the present mass-spring model exhibit a variety of complex behavior including transition to chaos in good agreement with experiments. Further, the mass-spring model reveals fundamental dynamics inherent in the dripping faucet system.Comment: 17 pages, 17 figure

The role of clock genes in sleep, stress and memory

Circadian clock genes serve as the molecular basis for animals' ∼24-h internal timekeeping. Clock gene expression inside and outside of the mammalian brain's circadian pacemaker (i.e. the SCN) integrates temporal information into a wealth of physiological processes. Ample data suggests that in addition to canonical cellular timekeeping functions, clock proteins also interact with proteins involved in cellular processes not related to timekeeping, including protein regulation and the interaction with other signaling mechanisms not directly linked to the regulation of circadian rhythms. Indeed, recent data suggests that clock genes outside the SCN are involved in fundamental brain processes such as sleep/wakefulness, stress and memory. The role of clock genes in these brain processes are complex and divers, influencing many molecular pathways and phenotypes. In this review, we will discuss recent work on the involvement of clock genes in sleep, stress, and memory. Moreover, we raise the controversial possibility that these functions may be under certain circumstances independent of their circadian timekeeping function

Organoids: a promising new in vitro platform in livestock and veterinary research.

Organoids are self-organizing, self-renewing three-dimensional cellular structures that resemble organs in structure and function. They can be derived from adult stem cells, embryonic stem cells, or induced pluripotent stem cells. They contain most of the relevant cell types with a topology and cell-to-cell interactions resembling that of the in vivo tissue. The widespread and increasing adoption of organoid-based technologies in human biomedical research is testament to their enormous potential in basic, translational- and applied-research. In a similar fashion there appear to be ample possibilities for research applications of organoids from livestock and companion animals. Furthermore, organoids as in vitro models offer a great possibility to reduce the use of experimental animals. Here, we provide an overview of studies on organoids in livestock and companion animal species, with focus on the methods developed for organoids from a variety of tissues/organs from various animal species and on the applications in veterinary research. Current limitations, and ongoing research to address these limitations, are discussed. Further, we elaborate on a number of fields of research in animal nutrition, host-microbe interactions, animal breeding and genomics, and animal biotechnology, in which organoids may have great potential as an in vitro research tool