The Simons Observatory: A fully remote controlled calibration system with a sparse wire grid for cosmic microwave background telescopes

For cosmic microwave background (CMB) polarization observations, calibration of detector polarization angles is essential. We have developed a fully remote controlled calibration system with a sparse wire grid that reflects linearly polarized light along the wire direction. The new feature is a remote-controlled system for regular calibration, which has not been possible in sparse wire grid calibrators in past experiments. The remote control can be achieved by two electric linear actuators that load or unload the sparse wire grid into a position centered on the optical axis of a telescope between the calibration time and CMB observation. Furthermore, the sparse wire grid can be rotated by a motor. A rotary encoder and a gravity sensor are installed on the sparse wire grid to monitor the wire direction. They allow us to achieve detector angle calibration with expected systematic error of $0.08^{\circ}$. The calibration system will be installed in small-aperture telescopes at Simons Observatory

Ultraviolet Continuum Color Variability of Luminous Sloan Digital Sky Survey QSOs

We examine whether the spectral energy distribution of UV continuum emission of active galactic nuclei changes during flux variation. We used multi-epoch photometric data of QSOs in the Stripe 82 observed by the SDSS Legacy Survey and selected 10 bright QSOs observed with high photometric accuracies, in the redshift range of z = 1.0-2.4 where strong broad emission lines such as Ly\alpha and CIV do not contaminate SDSS filters, to examine spectral variation of the UV continuum emission with broadband photometries. All target QSOs showed clear flux variations during the monitoring period 1998-2007, and the multi-epoch flux data in two different bands obtained on the same night showed a linear flux-to-flux relationship for all target QSOs. Assigning the flux in the longer wavelength to the x-axis in the flux-to-flux diagram, the x-intercept of the best-fit linear regression line was positive for most targets, which means that their colors in the observing bands become bluer as they become brighter. Then, the host-galaxy flux was estimated on the basis of the correlation between the stellar mass of the bulge of the host galaxy and the central black hole mass. We found that the longer-wavelength flux of the host galaxy was systematically smaller than that of the fainter extension of the best-fit regression line at the same shorter-wavelength flux for most targets. This result strongly indicates that the spectral shape of the continuum emission of QSOs in the UV region usually becomes bluer as it becomes brighter. We found that the multi-epoch flux-to-flux plots could be fitted well with the standard accretion disk model changing the mass accretion rate with a constant black hole mass for most targets. This finding strongly supports the standard accretion disk model for UV continuum emission of QSOs.Comment: 43 pages, 31 figures, accepted for publication in Ap

Microsurgical Training using Reusable Human Vessels from Discarded Tissues in Lymph Node Dissection

The use of human vessels at the beginning of microsurgery training is highly recommended. But vessels with the appropriate length for training are not often obtained. Whether these vessels may be reused for training has not been reported. Accordingly, we harvested vessels from discarded tissues in lymph node dissection and demonstrated that vascular anastomosis training using the same human vessels several times is possible by placing the vessels in a freezer and defrosting them with hot water. Vascular walls can be stored for microsurgical training until about 4 years after harvest, as shown in the gross appearance and histologic findings of our preserved vessels. We recommend the technique presented here for the longterm reuse of human vessels for microsurgery training that closely resembles real procedures

Exposed Artificial Plate Covered With Perifascial Areolar Tissue as a Nonvascularized Graft

Summary:. Perifascial areolar tissue (PAT) is a loose connective tissue on deep fascia, such as on the groin, thigh, or temporal region, which has abundant vascular plexus and mesenchymal stem cells. Nonvascularized PAT grafts can survive even on hypovascular wound beds. Therefore, PAT grafting is a possible alternative to conventional flap surgery to cover exposed bone or artifacts. In this article, we describe 2 cases of PAT grafting for the treatment of skin ulcers with exposed bone and artificial plate after mandible reconstruction. After negative-pressure wound therapy, PAT was used to covering exposed artificial plate for both cases, and a skin graft onto the PAT graft was performed in 1 case. The ulcers improved in both cases without recurrence. The gold-standard treatment of intractable ulcers and fistulas with an exposed tendon, bone, or artifact is coverage by a well-vascularized skin flap. However, PAT grafting has advantages in similar situations, occasionally together with skin grafting and/or negative-pressure wound therapy, because it is technically simple and less invasive

A Novel Dissection Method of the Internal Mammary (Thoracic) Artery: Anastomotic Vessel of the DIEP Flap

Summary:. Deep inferior epigastric perforator flaps are commonly used for breast reconstruction using autologous tissue. For such free flaps, the internal mammary artery provides stable blood flow as the recipient for anastomosis. We report a novel dissection method of the internal mammary artery. First, the perichondrium and costal cartilage of the sternocostal joint are dissected with electrocautery. Then, the incision on the perichondrium is extended along the cephalic and caudal ends. Next, this C-shaped superficial layer of perichondrium is elevated from the cartilage. The cartilage is incompletely fractured with electrocautery, with the deep layer of perichondrium intact. Then, the cartilage is completely fractured by leverage and removed. The remaining deep layer of perichondrium is incised at the costochondral junction and shifted aside, revealing the internal mammary artery. The preserved perichondrium creates a rabbet joint to protect the anastomosed artery. This method not only enables a more reliable, safer dissection of the internal mammary artery, but also allows reusage of the perichondrium as underlayment in the setting of anastomosis, and coverage for the incised rib edge, protecting the anastomosed vessels

The Simons Observatory: A fully remote controlled calibration system with a sparse wire grid for cosmic microwave background telescopes

For cosmic microwave background (CMB) polarization observations, calibration of detector polarization angles is essential. We have developed a fully remote controlled calibration system with a sparse wire grid that reflects linearly polarized light along the wire direction. The new feature is a remote-controlled system for regular calibration, which has not been possible in sparse wire grid calibrators in past experiments. The remote control can be achieved by two electric linear actuators that load or unload the sparse wire grid into a position centered on the optical axis of a telescope between the calibration time and CMB observation. Furthermore, the sparse wire grid can be rotated by using a motor. A rotary encoder and a gravity sensor are installed on the sparse wire grid to monitor the wire direction. They allow us to achieve detector polarization angle calibration with an expected systematic error of 0.08°. The calibration system will be installed in small-aperture telescopes at Simons Observatory