High Contrast Imaging and Wavefront Control with a PIAA Coronagraph: Laboratory System Validation

The Phase-Induced Amplitude Apodization (PIAA) coronagraph is a high performance coronagraph concept able to work at small angular separation with little loss in throughput. We present results obtained with a laboratory PIAA system including active wavefront control. The system has a 94.3% throughput (excluding coating losses) and operates in air with monochromatic light. Our testbed achieved a 2.27e-7 raw contrast between 1.65 lambda/D (inner working angle of the coronagraph configuration tested) and 4.4 lambda/D (outer working angle). Through careful calibration, we were able to separate this residual light into a dynamic coherent component (turbulence, vibrations) at 4.5e-8 contrast and a static incoherent component (ghosts and/or polarization missmatch) at 1.6e-7 contrast. Pointing errors are controlled at the 1e-3 lambda/D level using a dedicated low order wavefront sensor. While not sufficient for direct imaging of Earth-like planets from space, the 2.27e-7 raw contrast achieved already exceeds requirements for a ground-based Extreme Adaptive Optics system aimed at direct detection of more massive exoplanets. We show that over a 4hr long period, averaged wavefront errors have been controlled to the 3.5e-9 contrast level. This result is particularly encouraging for ground based Extreme-AO systems relying on long term stability and absence of static wavefront errors to recover planets much fainter than the fast boiling speckle halo.Comment: 18 pages, 12 figures. Accepted for publication in PASP. The pointing control scheme for this system is described in a separate paper (Coronagraphic Low-Order Wave-Front Sensor: Principle and Application to a Phase-Induced Amplitude Coronagraph, The Astrophysical Journal, Volume 693, Issue 1, pp. 75-84 (2009)

EVALUATION OF MECHANICAL PROPERTIES OF KNEE EXTENSOR AND PATELLAR TENDON DURING SQUATTING BY MUSCLE CONTRACTION SENSOR METHOD

The purpose of this study was to investigate the mechanical properties of muscle-tendon can* during squatting. Fourteen males were participated in this study. The muscle activities of knee extensor during squatting were measured by surface electrompgraphy. The mechanical prop@ of knee extensor and patellar tendon were measured using a muscle contraction (MC) sensor. Muscle activities of the knee exten- during squatting showed a significant correlation to the MC signal. The mechanical properties of the knee extensor and patellar tendon were closely related to the angle of the knee joint MC signals of knee extensor shaved a consistency on each muscle related to patellar tendon. From these results, it is considered, that the method using an MC sensor is effective for evaluating the changes in dynamic tension in muscle-tendon complex during squatting

Gravitational Waves from Sub-lunar Mass Primordial Black Hole Binaries - A New Probe of Extradimensions

In many braneworld models, gravity is largely modified at the electro-weak scale ~ 1TeV. In such models, primordial black holes (PBHs) with lunar mass M ~ 10^{-7}M_sun might have been produced when the temperature of the universe was at ~ 1TeV. If a significant fraction of the dark halo of our galaxy consists of these lunar mass PBHs, a huge number of BH binaries will exist in our neighborhood. Third generation detectors such as EURO can detect gravitational waves from these binaries, and can also determine their chirp mass. With a new detector designed to be sensitive at high frequency bands greater than 1 kHz, the existence of extradimensions could be confirmed.Comment: 4 pages, 1 figure, typos correcte

Measurement of Ultrasonic Attenuation in Metals by the Pulse Method

A method for measuring ultrasonic attenuation in some common metals is described together with the results obtained in the frequency range from 500 Kc/s to 6 Mc/s by the use of pulse techniqes. Although the multiple-echo method has been widely applied in such measurement, many factors should be taken into consideration to obtain accurate results. In this research, to get rid as far as possible of errors due to these factors, many corrections were made in the use of the apparatus and the conditions of measurement. Attenuation constants were determined for four common metals, mild steel, cast iron, aluminum and copper. It seems that the resultant error is less than ±10 percent in every case

C-Arm-Free Minimally Invasive Cervical Pedicle Screw Fixation (MICEPS): A Technical Note

A minimally invasive posterolateral approach designed to avoid the lateral misplacement of midcervical pedicle screws was reported, but there is no technical report that describes this technique without C-arm fluoroscopy. We report the results of a 2.5 years follow-up of a 62-year-old female patient with C4 metastatic breast cancer. The patient suffered from severe neck pain and impending quadriplegia for 2 months after radiation therapy. We performed C-arm-free minimally invasive cervical pedicle screw fixation (MICEPS). The patient was suc-cessfully treated with surgery, and her neck pain was well controlled. She had neither neurological deficits nor neck pain at the final (2.5-year) follow-up. C-arm-free MICEPS is a useful technique; in addition, the sur-geons and staff have no risk of radiation exposure, there is a reduced need for postoperative imaging, and a decreased revision rate can be expected with C-arm-free MICEPS

Toward an effective approach for on‑farm experimentation: lessons learned from a case study of fertilizer application optimization in Japan

On-farm experimentation (OFE) is increasing worldwide. Appropriate OFE procedures may differ depending on the characteristics and circumstances surrounding farms, such as climate, field conditions, farm size, degree of agricultural digitalization, and a farmer’s socioeconomic background. This study aims to guide the future development of OFE in Japanese grain farming by examining the experimental setup, data analysis, and farmers’ activities within their socioeconomic and institutional communication and learning networks. The results of this typical OFE case study, which estimates a field’s economicallyoptimal fertilizer variable-rate application map for winter wheat production, are reported. The outcomes of the case study, which are intended to guide the direction of OFE development in Japan, were used as reference materials for a survey taken while interviewing farmers who had never been involved in OFE. Farmers’ answers showed that the economic return of site-specific management depends on farm and field size and exhibits economies of scale. A very high share of the profit increases provided by OFE data came from improvements in field-specific uniform rate management, not from within-field site-specific management. The interviews revealed that farmers open to OFE are more interested in increasing rice crop quality to earn price premiums than in increasing yield. Increased engagement with farmers in conducting OFEs could play a key role not only in generating data to guide farmers’ input management but also in fostering farmer collaboration to develop marketing strategies. This study is the first to propose future orientations of OFE research that target typical moderately-sized Japanese grain farms

Multi-channel SNSPD system with high detection efficiency at telecommunication wavelength

We developed a four-channel superconducting nanowire single-photon detector system based on a Gifford-McMahon cryocooler. All channels showed a system detection efficiency (at a 100 Hz dark-count rate) higher than 16% at 1550 nm wavelength, and the best channel showed a system DE of 21% and 30% at 1550 nm and 1310 nm wavelength, respectively.Comment: 10 pages, 4 figure

TEE image quality improvement with our devised probe cover

OBJECTIVE(S): Our hypothesis was that our devised transesophageal echocardiography probe cover with the capacity for pinpoint suction would improve image quality. DESIGN: Prospective cohort study. SETTING: Single tertiary medical center. PARTICIPANTS: Patients undergoing surgery requiring intraoperative transesophageal echocardiography. INTERVENTIONS: Suctioning with inserted orogastric tube. MEASUREMENTS AND MAIN RESULTS: Changes in image quality with suctioning were assessed by 2 methods. In method #1, investigators categorized the quality of all acquired images on a numeric scale based on each investigator\u27s impression (1: very poor, 2: poor, 3: acceptable, 4: good, and 5: very good). In method #2, the reproducibility of the left ventricular fraction area change (LV FAC) was assessed, assuming that improved transgastric midpapillary short-axis view image quality would yield better LV FAC reproducibility. With method #1, for midesophageal views, 26.5%, 70.5%, and 3.0% of images showed improved, the same, and worsened image quality, respectively. For transgastric views, 55.3%, 43.3%, and 1.4% showed improved, the same, and worsened image quality, respectively. For deep transgastric views, 60.0%, 38.0%, and 2.0% showed improved, the same, and worsened image quality, respectively. With method #2, the presuction group had an ICC of 0.942 (95% CI: 0.91, 0.965). The postsuction group had an ICC of 0.988 (95% CI: 0.981, 0.993). CONCLUSIONS: Our investigation validates the potential image quality improvement withour devised TEE probe cover. However, its clinical validity needs to be confirmed by further studies

Spectral Density of Sparse Sample Covariance Matrices

Applying the replica method of statistical mechanics, we evaluate the eigenvalue density of the large random matrix (sample covariance matrix) of the form $J = A^{\rm T} A$, where $A$ is an $M \times N$ real sparse random matrix. The difference from a dense random matrix is the most significant in the tail region of the spectrum. We compare the results of several approximation schemes, focusing on the behavior in the tail region.Comment: 22 pages, 4 figures, minor corrections mad