Sample records for background natural orifice

  1. Field calibration of orifice meters for natural gas flow

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ting, V.C.; Shen, J.J.S.

    1989-03-01

    This paper presents the orifice calibration results for nominal 15.24, 10.16, and 5.08-cm (6,4,2-in.) orifice meters conducted at the Chevron's Sand Hills natural gas flow measurement facility in Crane, Texas. Over 200 test runs were collected in a field environment to study the accuracy of the orifice meters. Data were obtained at beta ratios ranging from 0.12 to 0.74 at the nominal conditions of 4576 kPa and 27{sup 0}C (650 psig and 80{sup 0}F) with a 0.57 specific gravity processed, pipeline quality natural gas. A bank of critical flow nozzles was used as the flow rate proving device to calibratemore » the orifice meters. Orifice discharge coefficients were computed with ANSI/API 2530-1985 (AGA3) and ISO 5167/ASME MFC-3M-1984 equations for every set of data points. With the orifice bore Reynolds numbers ranging from 1 to 9 million, the Sand Hills calibration data bridge the gap between the Ohio State water data at low Reynolds numbers and Chevron's high Reynolds number test data taken at a large test facility in Venice, Louisiana. The test results also successfully demonstrate that orifice meters can be accurately proved with critical flow nozzles under realistic field conditions.« less

  2. Natural-orifice translumenal endoscopic surgery (NOTES): minimally invasive evolution or revolution?

    PubMed

    Mohan, Helen M; O'Riordan, James M; Winter, Desmond C

    2013-06-01

    Since the first animal experimental laparoscopy in 1902, minimal access techniques have revolutionized surgery. Using the natural orifice dates back to at least the second century when Soranus performed a vaginal hysterectomy. The main difference between traditional endolumenal surgery and the translumenal approach of natural-orifice translumenal endoscopic surgery (NOTES) is the intentional puncture of a healthy organ in NOTES to access a cavity or other organ. The aim of this review was to examine the past, present, and potential future role of NOTES in the context of other developments in minimal access surgery. NOTES is at an early stage in its development and a convincing benefit over laparoscopy has not been demonstrated. Concerns regarding complications, for example of viscerotomy closure, have limited the widespread uptake of pure NOTES. However, it is likely that technological advances for NOTES surgery will enhance conventional laparoscopic and endoscopic techniques.

  3. Surgery via natural orifices in human beings: yesterday, today, tomorrow.

    PubMed

    Moris, Demetrios N; Bramis, Konstantinos J; Mantonakis, Eleftherios I; Papalampros, Efstathios L; Petrou, Athanasios S; Papalampros, Alexandros E

    2012-07-01

    We performed an evaluation of models, techniques, and applicability to the clinical setting of natural orifice surgery (mainly natural orifice transluminal endoscopic surgery [NOTES]) primarily in general surgery procedures. NOTES has attracted much attention recently for its potential to establish a completely alternative approach to the traditional surgical procedures performed entirely through a natural orifice. Beyond the potentially scar-free surgery and abolishment of dermal incision-related complications, the safety and efficacy of this new surgical technology must be evaluated. Studies were identified by searching MEDLINE, EMBASE, Cochrane Library, and Entrez PubMed from 2007 to February 2011. Most of the references were identified from 2009 to 2010. There were limitations as far as the population that was evaluated (only human beings, no cadavers or animals) was concerned, but there were no limitations concerning the level of evidence of the studies that were evaluated. The studies that were deemed applicable for our review were published mainly from 2007 to 2010 (see Methods section). All the evaluated studies were conducted only in human beings. We studied the most common referred in the literature orifices such as vaginal, oral, gastric, esophageal, anal, or urethral. The optimal access route and method could not be established because of the different nature of each procedure. We mainly studied procedures in the field of general surgery such as cholecystectomy, intestinal cancers, renal cancers, appendectomy, mediastinoscopy, and peritoneoscopy. All procedures were feasible and most of them had an uneventful postoperative course. A number of technical problems were encountered, especially as far as pure NOTES procedures are concerned, which makes the need of developing new endoscopic instruments, to facilitate each approach, undeniable. NOTES is still in the early stages of development and more robust technologies will be needed to achieve reliable

  4. In vivo microrobots for natural orifice transluminal surgery. Current status and future perspectives.

    PubMed

    Forgione, A

    2009-06-01

    The possibility to operate inside the peritoneal cavity through small holes performed in hollow organs that is presented by Natural Orifice Transluminal Endoscopic Surgery (NOTES) represents a major paradigm shift in general surgery. While this new approach seems very appealing from patients' perspectives because it eliminates completely abdominal wall aggression and promises to reduce postoperative pain, it is very challenging for surgeons because of the major constraints imposed by both the mode of access and the limited technology currently available. For this reason NOTES applications at the present time are performed by only a few surgeons and mainly to perform non-complex procedures. While new devices are under development, many of them are trying mainly to simply improve current endoscopic platforms and seem not to offer breakthrough solutions. The numerous challenges introduced by natural orifice approaches require a radical shift in the conception of new technologies in order to make this emerging operative access safe and reproducible. The convergence of several enabling technologies in the field of miniaturization, communication and micro-mechatronics brings the possibility to realize on a large scale the revolutionary concept of miniature in vivo co-operative robots. These robots provide vision and task assistance without the constraints of the entry incision and have been shown in experimental settings to possess many qualities that could be ideal to partner with Natural Orifice Surgery. This article explores the current status of microrobotics as well as presents potential future scenarios of their applications in NOTES.

  5. NOViSE: a virtual natural orifice transluminal endoscopic surgery simulator.

    PubMed

    Korzeniowski, Przemyslaw; Barrow, Alastair; Sodergren, Mikael H; Hald, Niels; Bello, Fernando

    2016-12-01

    Natural orifice transluminal endoscopic surgery (NOTES) is a novel technique in minimally invasive surgery whereby a flexible endoscope is inserted via a natural orifice to gain access to the abdominal cavity, leaving no external scars. This innovative use of flexible endoscopy creates many new challenges and is associated with a steep learning curve for clinicians. We developed NOViSE-the first force-feedback-enabled virtual reality simulator for NOTES training supporting a flexible endoscope. The haptic device is custom-built, and the behaviour of the virtual flexible endoscope is based on an established theoretical framework-the Cosserat theory of elastic rods. We present the application of NOViSE to the simulation of a hybrid trans-gastric cholecystectomy procedure. Preliminary results of face, content and construct validation have previously shown that NOViSE delivers the required level of realism for training of endoscopic manipulation skills specific to NOTES. VR simulation of NOTES procedures can contribute to surgical training and improve the educational experience without putting patients at risk, raising ethical issues or requiring expensive animal or cadaver facilities. In the context of an experimental technique, NOViSE could potentially facilitate NOTES development and contribute to its wider use by keeping practitioners up to date with this novel surgical technique. NOViSE is a first prototype, and the initial results indicate that it provides promising foundations for further development.

  6. [Natural orifice translumenal endoscopic surgery: historical and future perspectives].

    PubMed

    Yasuda, Kazuhiro; Shiroshita, Hidefumi; Inomata, Masafumi; Kitano, Seigo

    2013-11-01

    Natural orifice translumenal endoscopic surgery (NOTES) has gained much attention worldwide since the first report of transgastric peritoneoscopy in a porcine model in 2004. In this review, we summarize and highlight the current status and future directions of NOTES. Thousands of human NOTES procedures have been performed. The most common procedures are cholecystectomy and appendectomy, mainly performed through transvaginal access in a hybrid fashion with laparoscopic assistance, and the general complication rate is acceptable. Although much work is still needed to refine the techniques for NOTES, the development of NOTES has the potential to create a paradigm shift in minimally invasive surgery.

  7. Development of a Haptic Interface for Natural Orifice Translumenal Endoscopic Surgery Simulation

    PubMed Central

    Dargar, Saurabh; Sankaranarayanan, Ganesh

    2016-01-01

    Natural orifice translumenal endoscopic surgery (NOTES) is a minimally invasive procedure, which utilizes the body’s natural orifices to gain access to the peritoneal cavity. The NOTES procedure is designed to minimize external scarring and patient trauma, however flexible endoscopy based pure NOTES procedures require critical scope handling skills. The delicate nature of the NOTES procedure requires extensive training, thus to improve access to training while reducing risk to patients we have designed and developed the VTEST©, a virtual reality NOTES simulator. As part of the simulator, a novel decoupled 2-DOF haptic device was developed to provide realistic force feedback to the user in training. A series of experiments were performed to determine the behavioral characteristics of the device. The device was found capable of rendering up to 5.62N and 0.190Nm of continuous force and torque in the translational and rotational DOF, respectively. The device possesses 18.1Hz and 5.7Hz of force bandwidth in the translational and rotational DOF, respectively. A feedforward friction compensator was also successfully implemented to minimize the negative impact of friction during the interaction with the device. In this work we have presented the detailed development and evaluation of the haptic device for the VTEST©. PMID:27008674

  8. Velocity profile survey in a 16-in. custody-transfer orifice meter for natural gas

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Shen, J.J.S.

    1991-02-01

    This paper describes a research project conducted at Chevron U.S.A. Inc.'s Venice, LA, facility to ascertain that the flow condition inside a nominal 16-in. (406-mm) custody-transfer orifice meter was in compliance with American Gas Assn. (AGA) requirements. The survey was conducted at four flow rates ranging from 160 to 200 MMscf/D (4.53 {times} 10{sup 6} to 5.66 {times} 10{sup 6} std m{sup 3}/d) of processed natural gas at 880 psia (6.1 MPa). Experimental data were collected by a portable data-acquisition system driven by a lap-top microcomputer. The measured profiles indicated that the flow was nearly fully developed at the orificemore » plate location, and no significant swirling motion was detected. This test successfully demonstrated the techniques and equipment developed for determining actual flow distributions inside orifice meters in the field under normal operating conditions. This technology can be used to detect detrimental flow profiles and to verify compliance with AGA requirements on flow conditions in custody-transfer orifice meters.« less

  9. Laparoscopic sleeve gastrectomy for morbid obesity with natural orifice specimen extraction (NOSE).

    PubMed

    Gunkova, P; Gunka, I; Zonca, P; Dostalik, J; Ihnat, P

    2015-01-01

    An experience with laparoscopic sleeve gastrectomy using the natural orifice specimen extraction (NOSE) technique. Bariatric surgery is nowadays the only long term effective obesity treatment method. Twenty one consecutive patients underwent laparoscopic sleeve gastrectomy with the use of natural orifice specimen extraction (NOSE) in the Surgical Clinic of Faculty Hospital Ostrava between May 2012 and August 2012. Inclusion criteria were the body mass index (BMI) higher than 35 kg/m2 or higher than 32 kg/m2 accompanied with relevant comorbidities. Among 21 patients in this series, there were three men (14.3%) and 18 women (85.7%). Their mean age was 40.9±10.2 years. Their mean preoperative BMI was 40.4±4.6 kg/m2. No patient had previous bariatric surgery, one patient had laparoscopic fundoplication. All operations were completed laparoscopically with no conversions to an open procedure. In two cases, laparoscopic cholecystectomy was performed and the gallbladder was extracted along with the gastric specimen by transgastric approach. Laparoscopic sleeve gastrectomy is a safe and effective bariatric procedure with low morbidity and mortality. Based on our initial experiences it could be an indication for NOSE with transgastric approach. Obese patients would benefit from this approach due to the elimination of wound complications (Tab. 2, Fig. 3, Ref. 22).

  10. Thrust Measurements of an Underexpanded Orifice in the Transitional Regime

    NASA Astrophysics Data System (ADS)

    Ketsdever, Andrew D.

    2003-05-01

    The popularity of micropropulsion system development has led to renewed interest in the determination of propulsive properties of orifice flows since micronozzle expansions may suffer high viscous losses at low pressure operation. The mass flow and relative thrust for an under expanded orifice is measured as a function of orifice stagnation pressure from 0.1 to 3.5 Torr. Nitrogen, argon, and helium propellant gases are passed through a 1.0 mm diameter orifice with a wall thickness of 0.015 mm . Near-free molecule, transitional and continuum flow regimes are studied. The relative thrust is determined by a novel thrust stand designed primarily for low operating pressure, micropropulsion systems. It is shown that the thrust indications obtained from the stand are a function of the facility background pressure, and corrections are made to determine the indicated thrust for a zero background pressure with nitrogen as propellant. Highly repeatable (within 1 %) indicated thrust measurements are obtained in the thrust range from 5 to 500 μN.

  11. Patient Perceptions of Natural Orifice Translumenal Surgery

    PubMed Central

    Tsang, Melanie E.; Theman, Kirstin; Mercer, Dale; Hopman, Wilma M.; Hookey, Lawrence

    2012-01-01

    Natural orifice translumenal endoscopic surgery (NOTES) is on the forefront of surgical technique, but existing research has produced mixed results regarding factors associated with interest in the procedure. Our objective was to ascertain patient opinions at a Canadian centre regarding scarless surgery. A survey comprising demographic data (gender, age, body mass index [BMI]), interest in NOTES, impact of increased risk, as well as importance of further research and shorter recovery time was administered to volunteer patients at outpatient general surgery clinics. Nonparametric tests were utilized to examine difference in response by age, sex, BMI, and preexisting scars. Of the 335 participants (57% female, mean age of 54.5 ± 15.9 years, mean BMI of 28.7 ± 6.9), the majority (83%) showed some interest, but this dropped to 38% when additional risk was factored in. Generally, women, those under 50 years of age and those of healthy weight, were more interested than male, older, and/or heavier patients. Most felt that research into NOTES and reduced length of inpatient stay were important (80% and 95%, respectively). Further investigation into objective NOTES outcomes are needed to provide patients adequate data to make an informed choice regarding surgical route. PMID:22482048

  12. Experimental and numerical modeling of rarefied gas flows through orifices and short tubes

    NASA Astrophysics Data System (ADS)

    Gimelshein, S. F.; Markelov, G. N.; Lilly, T. C.; Selden, N. P.; Ketsdever, A. D.

    2005-05-01

    Flow through circular orifices with thickness-to-diameter ratios varying from 0.015 to 1.2 is studied experimentally and numerically with kinetic and continuum approaches. Helium and nitrogen gases are used in the range of Reynolds numbers from 0.02 to over 700. Good agreement between experimental and numerical results is observed for mass flow and thrust corrected for the experimental facility background pressure. For thick-to-thin orifice ratios of mass flow and thrust vs pressure, a minimum is established. The thick orifice propulsion efficiency is much higher than that of a thin orifice. The effects of edge roundness and surface specularity on a thick orifice specific impulse were found to be relatively small.

  13. The German registry for natural orifice translumenal endoscopic surgery: report of the first 551 patients.

    PubMed

    Lehmann, Kai S; Ritz, Jörg P; Wibmer, Andreas; Gellert, Klaus; Zornig, Carsten; Burghardt, Jens; Büsing, Martin; Runkel, Norbert; Kohlhaw, Kay; Albrecht, Roland; Kirchner, Tom G; Arlt, Georg; Mall, Julian W; Butters, Michael; Bulian, Dirk R; Bretschneider, Jörgen; Holmer, Christoph; Buhr, Heinz J

    2010-08-01

    To analyze patient outcome in the first 14 months of the German natural orifice translumenal endoscopic surgery (NOTES) registry (GNR). NOTES is a new surgical concept, which permits scarless intra-abdominal operations through natural orifices, such as the mouth, vagina, rectum, or urethra. The GNR was established as a nationwide outcome database to allow the monitoring and safe introduction of this technique in Germany. The GNR was designed as a voluntary database with online access. All surgeons in Germany who performed NOTES procedures were requested to participate in the registry. The GNR recorded demographical and therapy data as well as data on the postoperative course. A total of 572 target organs were operated in 551 patients. Cholecystectomies accounted for 85.3% of all NOTES procedures. All procedures were performed in female patients using transvaginal hybrid technique. Complications occurred in 3.1% of all patients, conversions to laparoscopy or open surgery in 4.9%. In cholecystectomies, institutional case volume, obesity, and age had substantial effect on conversion rate, operation length, and length of hospital stay, but no effect on complications. Despite the fact that NOTES has just recently been introduced, the technique has already gained considerable clinical application. Transvaginal hybrid NOTES cholecystectomy is a practicable and safe alternative to laparoscopic resection even in obese or older patients.

  14. Effect of mitral orifice shape on intra-ventricular filling fluid dynamics

    NASA Astrophysics Data System (ADS)

    Okafor, Ikechukwu; Angirish, Yagna; Yoganathan, Ajit; Santhanakrishnan, Arvind

    2013-11-01

    The natural geometry of the mitral orifice is D-shaped. However, most current designs of prosthetic valves employ O-shaped orifice geometry. The goal of this study was to compare the effect of geometrical modification between the D and O orifice on the intra-ventricular fluid dynamics during diastolic filling. The different mitral orifice geometries were incorporated into an in vitro left heart simulator consisting of a flexible-walled anatomical left ventricle (LV) physical model enclosed in an acrylic housing. Physiological flow rates and pressures were obtained via tuning systemic resistance and compliance elements in the flow loop. A programmable piston pump was used to generate the LV model wall motion. 2D Particle image velocimetry measurements were conducted along multiple longitudinal planes perpendicular to the annulus plane. During peak diastole, the incoming jet width at the LV central plane was smaller for the D-orifice than that of the O-orifice. Further, the core of the vortex ring in the D-orifice was reduced in size compared to that of the O-orifice. The spatiotemporal spreading of the inflow jet as well as the propagation of the vortex ring will be discussed. This study was funded by a grant from the National Heart, Lung and Blood Institute (RO1HL70262).

  15. Reduction of Orifice-Induced Pressure Errors

    NASA Technical Reports Server (NTRS)

    Plentovich, Elizabeth B.; Gloss, Blair B.; Eves, John W.; Stack, John P.

    1987-01-01

    Use of porous-plug orifice reduces or eliminates errors, induced by orifice itself, in measuring static pressure on airfoil surface in wind-tunnel experiments. Piece of sintered metal press-fitted into static-pressure orifice so it matches surface contour of model. Porous material reduces orifice-induced pressure error associated with conventional orifice of same or smaller diameter. Also reduces or eliminates additional errors in pressure measurement caused by orifice imperfections. Provides more accurate measurements in regions with very thin boundary layers.

  16. Drilling Precise Orifices and Slots

    NASA Technical Reports Server (NTRS)

    Richards, C. W.; Seidler, J. E.

    1983-01-01

    Reaction control thrustor injector requires precisely machined orifices and slots. Tooling setup consists of rotary table, numerical control system and torque sensitive drill press. Components used to drill oxidizer orifices. Electric discharge machine drills fuel-feed orifices. Device automates production of identical parts so several are completed in less time than previously.

  17. Development of a Virtual Reality Simulator for Natural Orifice Translumenal Endoscopic Surgery (NOTES) Cholecystectomy Procedure.

    PubMed

    Ahn, Woojin; Dargar, Saurabh; Halic, Tansel; Lee, Jason; Li, Baichun; Pan, Junjun; Sankaranarayanan, Ganesh; Roberts, Kurt; De, Suvranu

    2014-01-01

    The first virtual-reality-based simulator for Natural Orifice Translumenal Endoscopic Surgery (NOTES) is developed called the Virtual Translumenal Endoscopic Surgery Trainer (VTESTTM). VTESTTM aims to simulate hybrid NOTES cholecystectomy procedure using a rigid scope inserted through the vaginal port. The hardware interface is designed for accurate motion tracking of the scope and laparoscopic instruments to reproduce the unique hand-eye coordination. The haptic-enabled multimodal interactive simulation includes exposing the Calot's triangle and detaching the gall bladder while performing electrosurgery. The developed VTESTTM was demonstrated and validated at NOSCAR 2013.

  18. Natural orifice translumenal endoscopic surgery (NOTES): emerging trends and specifications for a virtual simulator.

    PubMed

    Schwaitzberg, Steven D; Dorozhkin, Denis; Sankaranarayanan, Ganesh; Matthes, Kai; Jones, Daniel B; De, Suvranu

    2016-01-01

    A virtual translumenal endoscopic surgical trainer (VTEST) is being developed to accelerate the development of natural orifice translumenal endoscopic surgery (NOTES) procedures and devices in a safe and risk-free environment. For a rapidly developing field such as NOTES, a needs analysis must be conducted regularly to discover emerging research trends and areas of potential high impact for a virtual simulator. This paper presents a survey-based study which follows a similar study conducted by this group in 2011 (Sankaranarayanan et al. in Surg Endosc 27:1607-1616, 2013). A 32-point questionnaire was distributed at the 2012 Natural Orifice Surgery Consortium for Assessment and Research annual meeting. These data were subsequently augmented by an identical online survey, targeted at the members of the American Society for Gastrointestinal Endoscopy and the Society of American Gastrointestinal and Endoscopic Surgeons, and analyzed. Twenty-eight NOTES experts participated in the 2012 study. Cholecystectomy (CE) procedure remained the most commonly performed NOTES technique, with 18 positive responses (64%). In contrast to 2011, the popularity of the NOTES appendectomy (AE) was significantly lower, with only 2 (7%) instances (CE vs. AE, p < 0.001), while the number of peroral endoscopic myotomy (POEM, PE) cases had increased significantly, with 11 (39%) positive responses, respectively (PE vs. AE, p = 0.013). Strong preference toward hybrid rather than pure NOTES techniques (82 vs. 11%, p < 0.001) was also expressed. Other responses were similar to those in the 2011 study, with the VTEST™ utility in developing and testing new techniques and instruments ranked particularly high. Based on the results of this study, a decision was made to focus exclusively on the transvaginal hybrid NOTES cholecystectomy procedure, including both rigid and flexible scope techniques. The importance of developing a virtual NOTES simulator was reaffirmed, with POEM identified as a

  19. Hybrid natural orifice transluminal endoscopic cholecystectomy: prospective human series.

    PubMed

    Cuadrado-Garcia, Angel; Noguera, Jose F; Olea-Martinez, Jose M; Morales, Rafael; Dolz, Carlos; Lozano, Luis; Vicens, Jose-Carlos; Pujol, Juan José

    2011-01-01

    Natural orifice transluminal endoscopic surgery (NOTES) makes it possible to perform intraperitoneal surgical procedures with a minimal number of access points in the abdominal wall. Currently, it is not possible to perform these interventions without the help of abdominal wall entryways, so these procedures are hybrids fusing minilaparoscopy and transluminal endoscopic surgery. This report presents a prospective clinical series of 25 patients who underwent transvaginal hybrid cholecystectomy for cholelithiasis. The study comprised a clinical series of 25 consecutive nonrandomized women who underwent a fusion transvaginal NOTES and minilaparoscopy procedure with two trocars for cholelithiasis: one 5-mm umbilical trocar and one 3-mm trocar in the upper left quadrant. The study had no control group. The scheduled surgical intervention was performed for all 25 women. No intraoperative complications occurred. One patient had mild hematuria that resolved in less than 12 h, but no other complications occurred during an average follow-up period of 140 days. Of the 25 women, 20 were discharged in 24 h, and 5 were discharged less than 12 h after the procedure. Hybrid transvaginal cholecystectomy, combining NOTES and minilaparoscopy, is a good surgical model for minimally invasive surgery. It can be performed in surgical settings where laparoscopy is practiced regularly using the instruments normally used for endoscopy and laparoscopic surgery. Due to the reproducibility of the intervention and the ease of vaginal closure, hybrid transvaginal cholecystectomy will permit further development of NOTES in the future.

  20. High Pressure Water Stripping Using Multi-Orifice Nozzles

    NASA Technical Reports Server (NTRS)

    Hoppe, David

    1999-01-01

    The use of multi-orifice rotary nozzles greatly increases the speed and stripping effectiveness of high pressure water blasting systems, but also greatly increases the complexity of selecting and optimizing the operating parameters. The rotational speed of the nozzle must be coupled with its transverse velocity as it passes across the surface of the substrate being stripped. The radial and angular positions of each orifice must be included in the analysis of the nozzle configuration. Orifices at the outer edge of the nozzle head move at a faster rate than the orifices located near the center. The energy transmitted to the surface from the impact force of the water stream from an outer orifice is therefore spread over a larger area than energy from an inner orifice. Utilizing a larger diameter orifice in the outer radial positions increases the total energy transmitted from the outer orifice to compensate for the wider distribution of energy. The total flow rate from the combination of all orifices must be monitored and should be kept below the pump capacity while choosing orifice to insert in each position. The energy distribution from the orifice pattern is further complicated since the rotary path of all the orifices in the nozzle head pass through the center section. All orifices contribute to the stripping in the center of the path while only the outer most orifice contributes to the stripping at the edge of the nozzle. Additional orifices contribute to the stripping from the outer edge toward the center section. With all these parameters to configure and each parameter change affecting the others, a computer model was developed to track and coordinate these parameters. The computer simulation graphically indicates the cumulative affect from each parameter selected. The result from the proper choices in parameters is a well designed, highly efficient stripping system. A poorly chosen set of parameters will cause the nozzle to strip aggressively in some areas

  1. Natural orifice transluminal endoscopic surgery in urology: Review of the world literature.

    PubMed

    Bazzi, Wassim M; Raheem, Omer A; Cohen, Seth A; Derweesh, Ithaar H

    2012-01-01

    Natural orifice transluminal endoscopic surgery (NOTES) has gained momentum in the recent urologic literature as a new surgical approach for intra-abdominal organs with scarless and painless postoperative recoveries. We sought to review the published literature concerning the safety and reproducibility of NOTES in urology. PubMed literature review of articles published in the English language was performed over a 10-year period, i.e., between 2001 and 2011; all articles were critically reviewed and analyzed. Despite its novelty, pure or hybrid surgical approaches have been adapted in performing NOTES. NOTES essentially utilizes transluminal flexible endoscopic instruments along with laparoscopic instruments to gain access to abdominal, pelvic, and/or retroperitoneal cavities. The preliminary results of NOTES in surgery and to a limited extent in urology appear promising, yet further research in animal survival and human cadaveric models is requisite prior to human applications, especially for complex surgeries. Future innovative research, particularly biomedical engineering, should be directed to improving the technicality and mechanistic application of NOTES; hence, better safety and efficacy of NOTES.

  2. [Natural orifice trans-luminal endoscopic surgery (notes)--a new era in general surgery].

    PubMed

    Elazary, Ram; Horgan, Santiago; Talamini, Mark A; Rivkind, Avraham I; Mintz, Yoav

    2008-10-01

    Four years ago, a new surgical technique was presented, the natural orifice trans-luminal endoscopic surgery (NOTES). This technique provides an incisionless operation. The surgical devices are inserted into the peritoneal cavity through the gastrointestinal or the urogenital tracts. Today, a cholecystectomy can be performed using an advanced endoscope inserted through the stomach or the vagina. The advantages of NOTES are: reduced post operative pain, no hernias, no surgical wounds infections and better cosmetic results. The disadvantages are: difficulties in achieving safe enterotomy closure or a leak proof anastomosis, it necessitates performing more operations compared to open or laparoscopic operations in order to obtain the skills for performing these operations, and difficulties of acquiring satisfactory endoscopic vision due to lack of advanced technology. Several NOTES operations have already been performed in humans. However, many other surgical procedures were tested in laboratory animals. Development and improvement of surgical devices may promote this surgical modality in the future.

  3. High Pressure Water Stripping Using Multi-Orifice Nozzles

    NASA Technical Reports Server (NTRS)

    Hoppe, David T.

    1998-01-01

    The use of multi-orifice rotary nozzles not only increases the speed and stripping effectiveness of high pressure water blasting systems, but also greatly increases the complexity of selecting and optimizing the operating parameters. The rotational speed of the nozzle must be coupled with the transverse velocity of the nozzle as it passes across the surface of the substrate being stripped. The radial and angular positions of each orifice must be included in the analysis of the nozzle configuration. Since orifices at the outer edge of the nozzle head move at a faster rate than the orifice located near the center, the energy impact force of the water stream from the outer orifice is spread over a larger area than the water streams from the inner orifice. Utilizing a larger diameter orifice in the outer radial positions increases the energy impact to compensate for its wider force distribution. The total flow rate from the combination of orifices must be monitored and kept below the pump capacity while choosing an orifice to insert in each position. The energy distribution from the orifice pattern is further complicated since the rotary path of all orifices in the nozzle head pass through the center section, contributing to the stripping in this area while only the outer most orifice contributes to the stripping in the shell area at the extreme outside edge of the nozzle. From t he outer most shell to the center section, more orifices contribute to the stripping in each progressively reduced diameter shell. With all these parameters to configure and each parameter change affecting the others, a computer model was developed to track and coordinate these parameters. The computer simulation responds by graphically indicating the cumulative affect from each parameter selected. The results from the proper choices in parameters is a well designed, highly efficient stripping system. A poorly chosen set of parameters will cause the nozzle to strip aggressively in some areas

  4. Effects of Reynolds number on orifice induced pressure error

    NASA Technical Reports Server (NTRS)

    Plentovich, E. B.; Gloss, B. B.

    1982-01-01

    Data previously reported for orifice induced pressure errors are extended to the case of higher Reynolds number flows, and a remedy is presented in the form of a porous metal plug for the orifice. Test orifices with apertures 0.330, 0.660, and 1.321 cm in diam. were fabricated on a flat plate for trials in the NASA Langley wind tunnel at Mach numbers 0.40-0.72. A boundary layer survey rake was also mounted on the flat plate to allow measurement of the total boundary layer pressures at the orifices. At the high Reynolds number flows studied, the orifice induced pressure error was found to be a function of the ratio of the orifice diameter to the boundary layer thickness. The error was effectively eliminated by the insertion of a porous metal disc set flush with the orifice outside surface.

  5. Successful balloon dilatation of both orifices in a case of double-orifice mitral valve with severe rheumatic stenosis.

    PubMed

    Nath, Ranjit Kumar; Soni, Dheeraj Kumar

    2016-08-01

    A 24-year-old female patient presented to us with progressive dyspnea on exertion for last three year. She was not a known case of rheumatic heart disease. Her physical examination showed regular pulse and her blood pressure was 100/76 mm Hg. Cardiac palpation showed grade 3 parasternal heave and auscultation revelled an accentuated first heart sound, loud P2 and mid-diastolic long rumbling murmur at apex and pansystolic murmur of tricuspid regurgitation at lower left sterna border. Chest X-ray showed evidence of grade 3 pulmonary venous congestion. Transthoracic and transesophageal two-dimensional echocardiography revealed a double-orifice mitral valve of complete bridge type at the leaflet level. Both orifice sizes were unequal, with the anterolateral orifice being smaller than its counterpart. There was moderate subvalvular fusion and both commisures were fused. Color doppler examination showed two separate mitral diastolic flows with mean gradients of 22 mm and 20 mm of Hg, respectively. There was no mitral regurgitation and no left atrial or appendage clot was seen by transesophageal echocardiography. Transseptal puncture was done by the modified fluoroscopic method. Posteromedial orifice was crossed with a 24 mm Inoue balloon and dilated using the stepwise dilation technique. Anterolateral orifice was not crossed by Inuoe balloon after multiple attempts. A TYSHAK (NuMAD Canada Inc.) balloon (16 × 40mm) was taken over the wire and inflated successfully across the anterolateral orifice with the help of transthoracic echocardiography guidance. Mean gradient become 9 and 8 mm across the medial and lateral orifice. Patient was discharged in stable condition after two day. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

  6. Natural orifice translumenal endoscopic surgery: Progress in humans since white paper

    PubMed Central

    Santos, Byron F; Hungness, Eric S

    2011-01-01

    Since the first description of the concept of natural orifice translumenal endoscopic surgery (NOTES), a substantial number of clinical NOTES reports have appeared in the literature. This editorial reviews the available human data addressing research questions originally proposed by the white paper, including determining the optimal method of access for NOTES, developing safe methods of lumenal closure, suturing and anastomotic devices, advanced multitasking platforms, addressing the risk of infection, managing complications, addressing challenges with visualization, and training for NOTES procedures. An analysis of the literature reveals that so far transvaginal access and closure appear to be the most feasible techniques for NOTES, with a limited, but growing transgastric, transrectal, and transesophageal NOTES experience in humans. The theoretically increased risk of infection as a result of NOTES procedures has not been substantiated in transvaginal and transgastric procedures so far. Development of suturing and anastomotic devices and advanced platforms for NOTES has progressed slowly, with limited clinical data on their use so far. Data on the optimal management and incidence of intraoperative complications remain sparse, although possible factors contributing to complications are discussed. Finally, this editorial discusses the likely direction of future NOTES development and its possible role in clinical practice. PMID:21483624

  7. Displacement of ureteral orifices following anterior colporrhaphy.

    PubMed

    Dain, Lena; Auslander, Ron; Lissak, Arie; Lavie, Ofer; Abramov, Yoram

    2010-01-01

    It is currently unknown whether ureteral orifices maintain their anatomic location after reconstructive pelvic surgeries. We therefore aimed to assess ureteral orifices' location after anterior colporrhaphy. Between August and December 2007, patients undergoing anterior colporrhaphy for advanced cystocele in our institution underwent cystoscopy with intravenous dye injection and placement of ureteral catheters before and after the surgery. Each ureteral orifice location was marked on an X-Y coordinate on the posterior bladder wall before and after surgery. Thirteen women aged 44-80 years were included in the study. Postoperatively, ureteral orifices were noted to migrate 0.65 +/- 0.3 cm caudally (closer to the urethrovesical junction) (p = 0.002) and 0.32 +/- 0.5 cm laterally (p < 0.05). Anterior colporrhaphy is associated with significant caudal and lateral displacement of both ureteral orifices. These findings are of potential importance for pelvic reconstructive surgeons and may facilitate faster cystoscopic evaluation of ureteral patency postoperatively. They may also have implications on the angle of the preferred optical equipment to be used.

  8. Women's Perception of Transvaginal Natural Orifice Transluminal Endoscopic Surgery (NOTES): Results of a Survey of Female Medical Staff and Literature Review.

    PubMed

    Gerntke, Carina Isabel; Kersten, Jan Felix; Schön, Gerhard; Mann, Oliver; Stark, Michael; Benhidjeb, Tahar

    2016-04-01

    Over the past 8 years, natural orifice transluminal endoscopic surgery (NOTES) has developed from preclinical to routine clinical practice. However, there are still concerns regarding the transvaginal approach. In our survey, we were interested in females with a professional medical background, thus having at least a basic medical understanding, which might discriminate between objective and subjective concerns. A questionnaire with 14 items was distributed among 1895 female physicians and nursing and administration staff of the University Medical Center Hamburg-Eppendorf. In addition, a qualitative literature review was performed. Data analysis was carried out using statistical package R version 2.15.0. The questionnaire was answered anonymously by 553 employees (29%). Fifty-seven percent were nurses, 18.6% belonged to administration, and 17% were physicians. A total of 63.1% of our respondents would choose the transvaginal NOTES technique for an assumed ovariectomy, while only 30.4% would choose this access for cholecystectomy. Doubts regarding transvaginal NOTES were related to sexual dysfunction (44.8%), its experimental nature (43.8%), future pregnancies (36.8%), and ethical reasons (30.3%). The literature review showed that women's perception of the transvaginal access is documented very heterogeneously and therefore difficult to compare. Despite the good reported results of NOTES and the medical background of the surveyed female employees, our study and the literature review clearly shows that there are fears regarding the transvaginal access, which might be a result of limited information. More accurate explanation of the available methods by the attending surgeon can lead to a better choice of the patient's preferred method. © The Author(s) 2015.

  9. Current status and future perspectives in laparoendoscopic single-site and natural orifice transluminal endoscopic urological surgery.

    PubMed

    Autorino, Riccardo; Stein, Robert J; Lima, Estevão; Damiano, Rocco; Khanna, Rakesh; Haber, Georges-Pascal; White, Michael A; Kaouk, Jihad H

    2010-05-01

    Objective of this study is to provide an evidence-based analysis of the current status and future perspectives of scarless urological surgery. A PubMed search has been performed for all relevant urological literature regarding natural orifice transluminal endoscopic surgery (NOTES) and laparoendoscopic single-site surgery (LESS). In addition, experience with LESS and NOTES at our own institution has been considered. All clinical and investigative reports for LESS and NOTES procedures in the urological literature have been considered. A wide variety of clinical procedures in urology have been successfully completed by using LESS techniques. Thus far, experience with NOTES has largely been investigational, although early clinical reports are emerging. Further development of instrumentation and platforms is necessary for both techniques to become more widely adopted throughout the urological community.

  10. Natural orifice transluminal endoscopic surgery for intra-abdominal emergency conditions.

    PubMed

    Bingener, J; Ibrahim-zada, I

    2014-01-01

    Patient benefits from natural orifice transluminal endoscopic surgery (NOTES) are of interest in acute-care surgery. This review provides an overview of the historical development of NOTES procedures, and addresses their current uses and limitations for intra-abdominal emergency conditions. A PubMed search was carried out for articles describing NOTES approaches for appendicectomy, percutaneous gastrostomy, hollow viscus perforation and pancreatic necrosectomy. Pertinent articles were reviewed and data on available outcomes synthesized. Emergency conditions in surgery tax the patient's cardiovascular and respiratory systems, and fluid and electrolyte balance. The operative intervention itself leads to an inflammatory response and blood loss, thus adding to the physiological stress. NOTES provides a minimally invasive alternative access to the peritoneal cavity, avoiding abdominal wall incisions. A clear advantage to the patient is evident with the implementation of an endoscopic approach to deal with inadvertently displaced percutaneous endoscopic gastrostomy tubes and perforated gastroduodenal ulcer. The NOTES approach appears less invasive for patients with infected pancreatic necrosis, in whom it allows surgical debridement and avoidance of open necrosectomy. Transvaginal appendicectomy is the second most frequently performed NOTES procedure after cholecystectomy. The NOTES concept has provided a change in perspective for intramural and transmural endoscopic approaches to iatrogenic perforations during endoscopy. NOTES approaches have been implemented in clinical practice over the past decade. Selected techniques offer reduced invasiveness for patients with intra-abdominal emergencies, and may improve outcomes. Steady future development and adoption of NOTES are likely to follow as technology improves and surgeons become comfortable with the approaches. © 2013 BJS Society Ltd. Published by John Wiley & Sons Ltd.

  11. Experimental investigation of hydrodynamic cavitation through orifices of different geometries

    NASA Astrophysics Data System (ADS)

    Rudolf, Pavel; Kubina, Dávid; Hudec, Martin; Kozák, Jiří; Maršálek, Blahoslav; Maršálková, Eliška; Pochylý, František

    Hydrodynamic cavitation in single and multihole orifices was experimentally investigated to assess their hydraulic characteristics: loss coefficients, inception cavitation number, cavitation number for transition to supercavitation. Significant difference for singlehole and multihole orifices was observed in terms of the measured loss coefficient. It is significantly more effective to use multihole orifices, where energy dissipation is much lower.It was found that using scaling factor given by ratio of orifice thickness suggests linear behaviour of both loss coefficient and inception cavitation number. Orifices seem to be convenient choice as flow constriction devices inducing cavitation due to their simplicity.

  12. A review on natural background radiation

    PubMed Central

    Shahbazi-Gahrouei, Daryoush; Gholami, Mehrdad; Setayandeh, Samaneh

    2013-01-01

    The world is naturally radioactive and approximately 82% of human-absorbed radiation doses, which are out of control, arise from natural sources such as cosmic, terrestrial, and exposure from inhalation or intake radiation sources. In recent years, several international studies have been carried out, which have reported different values regarding the effect of background radiation on human health. Gamma radiation emitted from natural sources (background radiation) is largely due to primordial radionuclides, mainly 232Th and 238U series, and their decay products, as well as 40K, which exist at trace levels in the earth's crust. Their concentrations in soil, sands, and rocks depend on the local geology of each region in the world. Naturally occurring radioactive materials generally contain terrestrial-origin radionuclides, left over since the creation of the earth. In addition, the existence of some springs and quarries increases the dose rate of background radiation in some regions that are known as high level background radiation regions. The type of building materials used in houses can also affect the dose rate of background radiations. The present review article was carried out to consider all of the natural radiations, including cosmic, terrestrial, and food radiation. PMID:24223380

  13. Study of orifice fabrication technologies for the liquid droplet radiator

    NASA Technical Reports Server (NTRS)

    Wallace, David B.; Hayes, Donald J.; Bush, J. Michael

    1991-01-01

    Eleven orifice fabrication technologies potentially applicable for a liquid droplet radiator are discussed. The evaluation is focused on technologies capable of yielding 25-150 microns diameter orifices with trajectory accuracies below 5 milliradians, ultimately in arrays of up to 4000 orifices. An initial analytical screening considering factors such as trajectory accuracy, manufacturability, and hydrodynamics of orifice flow is presented. Based on this screening, four technologies were selected for experimental evaluation. A jet straightness system used to test 50-orifice arrays made by electro-discharge machining (EDM), Fotoceram, and mechanical drilling is discussed. Measurements on orifice diameter control and jet trajectory accuracy are presented and discussed. Trajectory standard deviations are in the 4.6-10.0 milliradian range. Electroforming and EDM appear to have the greatest potential for Liquid Droplet Radiator applications. The direction of a future development effort is discussed.

  14. Flow balancing orifice for ITER toroidal field coil

    NASA Astrophysics Data System (ADS)

    Litvinovich, A. V.; Y Rodin, I.; Kovalchuk, O. A.; Safonov, A. V.; Stepanov, D. B.; Guryeva, T. M.

    2017-12-01

    Flow balancing orifices (FBOs) are used in in International thermonuclear experimental reactor (ITER) Toroidal Field coil to uniform flow rate of cooling gas in the side double pancakes which have a different conductor length: 99 m and 305 m, respectively. FBOs consist of straight parts, elbows produced from a 316L stainless steel tube 21.34 x 2.11 mm and orifices made from a 316L stainless steel rod. Each of right and left FBOs contains 6 orifices, straight FBOs contain 4 and 6 orifices. Before manufacturing of qualification samples D.V. Efremov Institute of Electrophysical Apparatus (JSC NIIEFA) proposed to ITER a new approach to provide the seamless connection between a tube and a plate therefore the most critical weld between the orifice with 1 mm thickness and the tube removed from the FBOs final design. The proposed orifice diameter is three times less than the minimum requirement of the ISO 5167, therefore it was tasked to define accuracy of calculation flow characteristics at room temperature and compare with the experimental data. In 2015 the qualification samples of flow balancing orifices were produced and tested. The results of experimental data showed that the deviation of calculated data is less than 7%. Based on this result and other tests ITER approved the design of FBOs, which made it possible to start the serial production. In 2016 JSC NIIEFA delivered 50 FBOs to ITER, i.e. 24 left side, 24 right side and 2 straight FBOs. In order to define the quality of FBOs the test facility in JSC NIIEFA was prepared. The helium tightness test at 10-9 m3·Pa/s the pressure up to 3 MPa, flow rate measuring at the various pressure drops, the non-destructive tests of orifices and weld seams (ISO 5817, class B) were conducted. Other tests such as check dimensions and thermo cycling 300 - 80 - 300 K also were carried out for each FBO.

  15. Calibration and use of filter test facility orifice plates

    NASA Astrophysics Data System (ADS)

    Fain, D. E.; Selby, T. W.

    1984-07-01

    There are three official DOE filter test facilities. These test facilities are used by the DOE, and others, to test nuclear grade HEPA filters to provide Quality Assurance that the filters meet the required specifications. The filters are tested for both filter efficiency and pressure drop. In the test equipment, standard orifice plates are used to set the specified flow rates for the tests. There has existed a need to calibrate the orifice plates from the three facilities with a common calibration source to assure that the facilities have comparable tests. A project has been undertaken to calibrate these orifice plates. In addition to reporting the results of the calibrations of the orifice plates, the means for using the calibration results will be discussed. A comparison of the orifice discharge coefficients for the orifice plates used at the seven facilities will be given. The pros and cons for the use of mass flow or volume flow rates for testing will be discussed. It is recommended that volume flow rates be used as a more practical and comparable means of testing filters. The rationale for this recommendation will be discussed.

  16. Apparatus for depositing hard coating in a nozzle orifice

    DOEpatents

    Flynn, P.L.; Giammarise, A.W.

    1995-02-21

    The present invention is directed to a process for coating the interior surfaces of an orifice in a substrate that forms a slurry fuel injection nozzle. In a specific embodiment, the nozzle is part of a fuel injection system for metering a coal-water slurry into a large, medium-speed, multi-cylinder diesel engine. In order to retard erosion of the orifice, the substrate is placed in a chemical vapor deposition (CVD) reaction chamber. A reaction gas is passed into the chamber at a gas temperature below its reaction temperature and is directed through the orifice in the substrate. The gas reaction temperature is a temperature at and above which the reaction gas deposits as a coating, and the reaction gas is of a composition whereby improved resistance to erosion by flow of the particulates in the slurry fuel is imparted by the deposited coating. Only the portion of the substrate in proximity to the orifice to be coated is selectively heated to at least the gas reaction temperature for effecting coating of the orifice`s interior surfaces by the vapor deposited coating formed from the reaction gas. 2 figs.

  17. "Triangle of safety": anatomic considerations in transvaginal natural orifice surgery.

    PubMed

    Roberts, Kurt; Solomon, Daniel; Bell, Robert; Duffy, Andrew

    2013-08-01

    The introduction of transvaginal (TV) natural orifice transluminal endoscopic surgery (NOTES) brings the loss of traditionally used cutaneous landmarks for safe peritoneal access. This video describes the use of landmarks within the posterior vaginal fornix to define a "triangle of safety" wherein the peritoneal cavity can be accessed while minimizing the risk of injury to surrounding structures. The triangle of safety is best identified in the following way. The cervix and posterior fornix are visualized. Then an imaginary clock located at the base of the cervix is envisioned. The superior two corners of the triangle are represented by the 4 and 8 o'clock positions on this imaginary clock. Sometimes the cervix needs to be grasped and elevated anteriorly so that the inferior apex of the triangle delineated by the center of the rectovaginal fold is better visualized. During hybrid TV NOTES, the rectovaginal pouch of Douglas is visualized from the umbilicus, and the vaginal port can then be safely passed through the center of the triangle. It is important that the vaginal port should be angled upward, aiming toward the umbilicus to avoid injury to the rectum. During pure TV NOTES, the incision is made with electrocautery from the 5 o'clock position to the 7 o'clock position within the triangle. The peritoneum is sharply entered, and the colpotomy is dilated with the surgeons' fingers. The triangle of safety defines a set of landmarks between the base of the cervix and the rectovaginal fold. It allows for a safe TV access for hybrid and pure TV NOTES while minimizing the risk of injury to surrounding structures.

  18. Numerical analysis of eccentric orifice plate using ANSYS Fluent software

    NASA Astrophysics Data System (ADS)

    Zahariea, D.

    2016-11-01

    In this paper the eccentric orifice plate is qualitative analysed as compared with the classical concentric orifice plate from the point of view of sedimentation tendency of solid particles in the fluid whose flow rate is measured. For this purpose, the numerical streamlines pattern will be compared for both orifice plates. The numerical analysis has been performed using ANSYS Fluent software. The methodology of CFD analysis is presented: creating the 3D solid model, fluid domain extraction, meshing, boundary condition, turbulence model, solving algorithm, convergence criterion, results and validation. Analysing the numerical streamlines, for the concentric orifice plate can be clearly observed two circumferential regions of separated flows, upstream and downstream of the orifice plate. The bottom part of these regions are the place where the solid particles could sediment. On the other hand, for the eccentric orifice plate, the streamlines pattern suggest that no sedimentation will occur because at the bottom area of the pipe there are no separated flows.

  19. Porous plug for reducing orifice induced pressure error in airfoils

    NASA Technical Reports Server (NTRS)

    Plentovich, Elizabeth B. (Inventor); Gloss, Blair B. (Inventor); Eves, John W. (Inventor); Stack, John P. (Inventor)

    1988-01-01

    A porous plug is provided for the reduction or elimination of positive error caused by the orifice during static pressure measurements of airfoils. The porous plug is press fitted into the orifice, thereby preventing the error caused either by fluid flow turning into the exposed orifice or by the fluid flow stagnating at the downstream edge of the orifice. In addition, the porous plug is made flush with the outer surface of the airfoil, by filing and polishing, to provide a smooth surface which alleviates the error caused by imperfections in the orifice. The porous plug is preferably made of sintered metal, which allows air to pass through the pores, so that the static pressure measurements can be made by remote transducers.

  20. Improved Orifice Plate for Spray Gun

    NASA Technical Reports Server (NTRS)

    Cunningham, W.

    1986-01-01

    Erratic spray pattern of commercial spray gun changed to repeatable one by simple redesign of two parts. In modified spray gun orifice plate and polytetrafluoroethylene bushing redesigned to assure centering and alignment with nozzle. Such improvement useful in many industrial applications requiring repeatable spray patterns. Might include spraying of foam insulation, paint, other protective coatings, detergents, abrasives, adhesives, process chemicals, or fuels. Unmodified spray gun produces erratic spray because lateral misalignment between orifice plate and nozzle.

  1. Subsonic tests of an all-flush-pressure-orifice air data system

    NASA Technical Reports Server (NTRS)

    Larson, T. J.; Siemers, P. M., III

    1981-01-01

    The use of an all-flush-pressure-orifice array as a subsonic air data system was evaluated in flight and wind tunnel tests. Two orifice configurations were investigated. Both used orifices arranged in a cruciform pattern on the airplane nose. One configuration also used orifices on the sides of the fuselage for a source of static pressure. The all-nose-orifice configuration was similar to the shuttle entry air data system (SEADS). The flight data were obtained with a KC-135A airplane. The wind tunnel data were acquired with a 0.035-scale model of the KC-135A airplane. With proper calibration, several orifices on the vertical centerline of the vehicle's nose were found to be satisfactory for the determination of total pressure and angle of attack. Angle of sideslip could be accurately determined from pressure measurements made on the horizontal centerline of the aircraft. Orifice pairs were also found that provided pressure ratio relationships suitable for the determination of Mach number. The accuracy that can be expected for the air data determined with SEADS during subsonic orbiter flight is indicated.

  2. Submucosal tunneling using endoscopic submucosal dissection for peritoneal access and closure in natural orifice transluminal endoscopic surgery: a porcine survival study.

    PubMed

    Yoshizumi, F; Yasuda, K; Kawaguchi, K; Suzuki, K; Shiraishi, N; Kitano, S

    2009-08-01

    Safe peritoneal access and gastric closure are the most important concerns in the clinical application of natural orifice transluminal endoscopic surgery (NOTES). We aimed to clarify the feasibility of a submucosal tunnel technique using endoscopic submucosal dissection (ESD) for transgastric peritoneal access and subsequent closure for NOTES. Seven female pigs, each weighing about 40 kg were included in the study. The following procedures were performed: (i) after injection of normal saline into the submucosa, the mucosa was cut with a flex knife; (ii) the submucosal layer was dissected using an insulation-tipped electrosurgical knife to make a narrow longitudinal 50-mm submucosal tunnel; (iii) a small incision was made at the end of the tunnel and enlarged with a dilation balloon. After transgastric peritoneoscopy, the mucosal incision site was closed with clips. The following outcome measures were used: (a) evaluation of the technical feasibility of making a submucosal tunnel; (b) clinical monitoring for 7 days; (c) follow-up endoscopy and necropsy; and (d) peritoneal fluid culture. Natural orifice transluminal endoscopic peritoneoscopy with a submucosal tunnel was successfully carried out in all pigs. The pigs recovered well, without signs of peritonitis. Follow-up endoscopy showed healing of mucosal incision sites without open defects. Necropsy revealed no findings of peritonitis, confirming completeness of gastric closure; there was a thin scar in one pig and adhesion of the omentum in six pigs. Peritoneal fluid culture demonstrated no bacterial growth. The submucosal tunnel technique is feasible and effective for transgastric peritoneal access and closure.

  3. Active Control of Liner Impedance by Varying Perforate Orifice Geometry

    NASA Technical Reports Server (NTRS)

    Ahuji, K. K.; Gaeta, R. J., Jr.

    2000-01-01

    The present work explored the feasibility of controlling the acoustic impedance of a resonant type acoustic liner. This was accomplished by translating one perforate over another of the same porosity creating a totally new perforate that had an intermediate porosity. This type of adjustable perforate created a variable orifice perforate whose orifices were non-circular. The key objective of the present study was to quantify, the degree of attenuation control that can be achieved by applying such a concept to the buried septum in a two-degree-of-freedom (2DOF) acoustic liner. An additional objective was to examine the adequacy of the existing impedance models to explain the behavior of the unique orifice shapes that result from the proposed silding perforate concept. Different orifice shapes with equivalent area were also examined to determine if highly non-circular orifices had a significant impact on the impedance.

  4. Killing rate of colony count by hydrodynamic cavitation due to square multi-orifice plates

    NASA Astrophysics Data System (ADS)

    Dong, Zhiyong; Zhao, Wenqian

    2018-02-01

    Currently,in water supply engineering, the conventional technique of disinfection by chlorination is employed to kill pathogenic microorganisms in raw water. However, chlorine reacts with organic compounds in water and generates disinfection byproducts (DBPs), such as trihalomethanes (THMs), haloacetic acids (HAAs) etc. These byproducts are of carcinogenic, teratogenic and mutagenic effects, which seriously threaten human health. Hydrodynamic cavitation is a novel technique of drinking water disinfection without DBPs. Effects of orifice size, orifice number and orifice layout of multi-orifice plate, cavitation number, cavitation time and orifice velocity on killing pathogenic microorganisms by cavitation were investigated experimentally in a self-developed square multi-orifice plate-type hydrodynamic cavitation device. The experimental results showed that cavitation effects increased with decrease in orifice size and increase in orifice number, cavitation time and orifice velocity. Along with lowering in cavitation number, there was an increase in Reynolds shear stress,thus enhancing the killing rate of pathogenic microorganism in raw water. In addition, the killing rate by staggered orifice layout was greater than that by checkerboard-type orifice layout.

  5. Process for depositing hard coating in a nozzle orifice

    DOEpatents

    Flynn, P.L.; Giammarise, A.W.

    1991-10-29

    The present invention is directed to a process for coating the interior surfaces of an orifice in a substrate that forms a slurry fuel injection nozzle. In a specific embodiment, the nozzle is part of a fuel injection system for metering a coal-water slurry into a large, medium-speed, multi-cylinder diesel engine. In order to retard erosion of the orifice, the substrate is placed in a chemical vapor deposition (CVD) reaction chamber. A reaction gas is passed into the chamber at a gas temperature below its reaction temperature and is directed through the orifice in the substrate. The gas reaction temperature is a temperature at and above which the reaction gas deposits as a coating, and the reaction gas is of a composition whereby improved resistance to erosion by flow of the particulates in the slurry fuel is imparted by the deposited coating. Only the portion of the substrate in proximity to the orifice to be coated is selectively heated to at least the gas reaction temperature for effecting coating of the orifice's interior surfaces by the vapor deposited coating formed from the reaction gas. 2 figures.

  6. Apparatus for depositing hard coating in a nozzle orifice

    DOEpatents

    Flynn, Paul L.; Giammarise, Anthony W.

    1995-01-01

    The present invention is directed to a process for coating the interior surfaces of an orifice in a substrate that forms a slurry fuel injection nozzle. In a specific embodiment, the nozzle is part of a fuel injection system for metering a coal-water slurry into a large, medium-speed, multi-cylinder diesel engine. In order to retard erosion of the orifice, the substrate is placed in a chemical vapor deposition (CVD) reaction chamber. A reaction gas is passed into the chamber at a gas temperature below its reaction temperature and is directed through the orifice in the substrate. The gas reaction temperature is a temperature at and above which the reaction gas deposits as a coating, and the reaction gas is of a composition whereby improved resistance to erosion by flow of the particulates in the slurry fuel is imparted by the deposited coating. Only the portion of the substrate in proximity to the orifice to be coated is selectively heated to at least the gas reaction temperature for effecting coating of the orifice's interior surfaces by the vapor deposited coating formed from the reaction gas.

  7. Process for depositing hard coating in a nozzle orifice

    DOEpatents

    Flynn, Paul L.; Giammarise, Anthony W.

    1991-01-01

    The present invention is directed to a process for coating the interior surfaces of an orifice in a substrate that forms a slurry fuel injection nozzle. In a specific embodiment, the nozzle is part of a fuel injection system for metering a coal-water slurry into a large, medium-speed, multi-cylinder diesel engine. In order to retard erosion of the orifice, the substrate is placed in a chemical vapor deposition (CVD) reaction chamber. A reaction gas is passed into the chamber at a gas temperature below its reaction temperature and is directed through the orifice in the substrate. The gas reaction temperature is a temperature at and above which the reaction gas deposits as a coating, and the reaction gas is of a composition whereby improved resistance toerosion by flow of the particulates in the slurry fuel is imparted by the deposited coating. Only the portion of the substrate in proximity to the orifice to be coated is selectively heated to at least the gas reaction temperature for effecting coating of the orifice's interior surfaces by the vapor deposited coating formed from the reaction gas.

  8. Optimization of Orifice Geometry for Cross-Flow Mixing in a Cylindrical Duct

    NASA Technical Reports Server (NTRS)

    Sowa, W. A.; Kroll, J. T.; Samuelsen, G. S.; Holdeman, J. D.

    1994-01-01

    Mixing of gaseous jets in a cross-flow has significant applications in engineering, one example of which is the dilution zone of a gas turbine combustor. Despite years of study, the design of jet injection in combustors is largely based on practical experience. A series of experiments was undertaken to delineate the optimal mixer orifice geometry. A cross-flow to core-flow momentum-flux ratio of 40 and a mass flow ratio of 2.5 were selected as representative of an advanced design. An experimental test matrix was designed around three variables: the number of orifices, the orifice aspect ratio (long-to-short dimension), and the orifice angle. A regression analysis was performed on the data to arrive at an interpolating equation that predicted the mixing performance of orifice geometry combinations within the range of the test matrix parameters. Results indicate that mixture uniformity is a non-linear function of the number of orifices, the orifice aspect ratio, and the orifice angle. Optimum mixing occurs when the asymptotic mean jet trajectories are in the range of 0.35 less than r/R less than 0.5 (where r = 0 is at the mixer wall) at z/R = 1.0. At the optimum number of orifices, the difference between shallow-angled slots with large aspect ratios and round holes is minimal and either approach will lead to good mixing performance. At the optimum number of orifices, it appears possible to have two local optimums where one corresponds to an aspect ratio of 1.0 and the other to a high aspect ratio.

  9. Pressure atomizer having multiple orifices and turbulent generation feature

    DOEpatents

    VanBrocklin, Paul G.; Geiger, Gail E.; Moran, Donald James; Fournier, Stephane

    2002-01-01

    A pressure atomizer includes a silicon plate having a top surface and a bottom surface. A portion of the top surface defines a turbulent chamber. The turbulent chamber is peripherally bounded by the top surface of the plate. The turbulent chamber is recessed a predetermined depth relative to the top surface. The silicon plate further defines at least one flow orifice. Each flow orifice extends from the bottom surface of the silicon plate to intersect with and open into the turbulent chamber. Each flow orifice is in fluid communication with the turbulent chamber.

  10. Multihole Arc-Welding Orifice

    NASA Technical Reports Server (NTRS)

    Swaim, Benji D.

    1989-01-01

    Modified orifice for variable-polarity plasma-arc welding directs welding plume so it creates clean, even welds on both Inconel(R) and aluminum alloys. Includes eight holes to relieve back pressure in plasma. Quality of welds on ferrous and nonferrous alloys improved as result.

  11. Asian-Chinese patient perceptions of natural orifice transluminal endoscopic surgery cholecystectomy.

    PubMed

    Teoh, Anthony Yuen Bun; Ng, Enders Kwok Wai; Chock, Alana; Swanstrom, Lee; Varadarajulu, Shyam; Chiu, Philip Wai Yan

    2014-05-01

    Patient and physician perceptions of natural orifice transluminal endoscopic surgery (NOTES) have been reported for the Western population. However, whether Asian-Chinese patients share the same perspectives as compared to the Western population is unknown. This was a cross-sectional survey carried out in the surgical outpatient's clinic at the Prince of Wales Hospital between June and September 2011. Patients were provided with an information leaflet and asked to complete a questionnaire regarding their perceptions of and preferences for NOTES cholecystectomy. Female patients attending the clinic were given an additional questionnaire regarding attitudes towards transvaginal surgery. Two hundred patients were recruited to complete the questionnaire(s) and the male to female ratio was 1:1. One hundred and fourteen patients (57%) preferred to undergo NOTES cholecystectomy for cosmetic reasons (P=0.009). Oral and anal routes were both acceptable for NOTES accesses in males and females. Forty-one percent of the female patients would consider transvaginal NOTES. Of these patients, significantly more patients indicated that the reason for choosing transvaginal NOTES was to minimize the risk of hernia (P=0.016) and to reduce pain associated with the procedure (P=0.017). The risk of complications (84.5%) and the cost of the procedure (58%) were considered the most important aspects when choosing a surgical approach by Asian-Chinese patients. Asian-Chinese preferred NOTES mainly for cosmetic reasons. However, the transvaginal route was less acceptable to females. Significant differences in patient perception on NOTES were observed between Asian-Chinese and Western patients. © 2013 The Authors. Digestive Endoscopy © 2013 Japan Gastroenterological Endoscopy Society.

  12. Effect of slotted exit orifice on performance of plasma synthetic jet actuator

    NASA Astrophysics Data System (ADS)

    Zong, Haohua; Kotsonis, Marios

    2017-03-01

    This study experimentally investigates the influence of exit orifice shape on the performance characteristics of a three-electrode plasma synthetic jet actuator. High-speed Schlieren imaging system and phase-locked two-component PIV measurements are used for flowfield characterisation in quiescent conditions. Two actuator configurations with the same exit area but different exit orifice shape (round orifice and slot orifice) are studied. Results indicate a close correspondence between the shapes of the starting vortex ring with the shapes of the respective exit orifices. For the slot orifice, the elongated starting vortex ring gradually expands during propagation, while its ends become warped. A distinct K-H instability structure is observed, inducing continuous oscillation of the high-speed jet. Compared with the jet from the round orifice, the slot jet has a higher entrainment rate of surrounding air, thus resulting in a lower propagation velocity of the jet front. The exit velocity of PSJA within one period initially shows a rapid increase, then persists at a relatively high level (100-130 m/s), and finally drops with some small-scale oscillations. The oscillation amplitude is less than 10 m/s, and the oscillation period is approximately 600 µs. Under conditions of same exit area, orifice shape has little influence on the variation of the exit velocity.

  13. Teaching about Natural Background Radiation

    ERIC Educational Resources Information Center

    Al-Azmi, Darwish; Karunakara, N.; Mustapha, Amidu O.

    2013-01-01

    Ambient gamma dose rates in air were measured at different locations (indoors and outdoors) to demonstrate the ubiquitous nature of natural background radiation in the environment and to show that levels vary from one location to another, depending on the underlying geology. The effect of a lead shield on a gamma radiation field was also…

  14. Natural orifice transendoluminal surgery and laparoendoscopic single-site surgery: the future of laparoscopic radical prostatectomy.

    PubMed

    Barret, Eric; Sanchez-Salas, Rafael; Ercolani, Matthew C; Rozet, Francois; Galiano, Marc; Cathelineau, Xavier

    2011-03-01

    Techniques for minimally invasive radical prostatectomy (RP) have been carefully reviewed by surgical teams worldwide in order to identify possible weaknesses and facilitate further improvement in their overall performance. The initial plan of action has been to carefully study the best-practice techniques for open RP in order to reproduce and standardize performance from the laparoscopic perspective. Similar to open surgery, the learning curve of minimally invasive RP has been well documented in terms of objective evaluation of outcomes for cancer control and functional results. Natural orifice transluminal endoscopic surgery (NOTES) and laparoendoscopic single-site surgery (LESS) have recently gained momentum as feasible techniques for minimal access urological surgery. NOTES-LESS drastically limit the surgeon's ability to choose the site of entry for operative instruments; therefore, the advantages of NOTES-LESS are gained with the understanding that the surgical procedure is more technically challenging. There are several key elements in RP techniques (in particular, dorsal vein control, apex exposure and cavernosal nerve sparing) that can have significant implications on oncologic and functional results. These steps are hard to perform in a limited working field. LESS radical prostatectomy can clearly be facilitated by using robotic technology.

  15. Gas Generator Feedline Orifice Sizing Methodology: Effects of Unsteadiness and Non-Axisymmetric Flow

    NASA Technical Reports Server (NTRS)

    Rothermel, Jeffry; West, Jeffrey S.

    2011-01-01

    Engine LH2 and LO2 gas generator feed assemblies were modeled with computational fluid dynamics (CFD) methods at 100% rated power level, using on-center square- and round-edge orifices. The purpose of the orifices is to regulate the flow of fuel and oxidizer to the gas generator, enabling optimal power supply to the turbine and pump assemblies. The unsteady Reynolds-Averaged Navier-Stokes equations were solved on unstructured grids at second-order spatial and temporal accuracy. The LO2 model was validated against published experimental data and semi-empirical relationships for thin-plate orifices over a range of Reynolds numbers. Predictions for the LO2 square- and round-edge orifices precisely match experiment and semi-empirical formulas, despite complex feedline geometry whereby a portion of the flow from the engine main feedlines travels at a right-angle through a smaller-diameter pipe containing the orifice. Predictions for LH2 square- and round-edge orifice designs match experiment and semi-empirical formulas to varying degrees depending on the semi-empirical formula being evaluated. LO2 mass flow rate through the square-edge orifice is predicted to be 25 percent less than the flow rate budgeted in the original engine balance, which was subsequently modified. LH2 mass flow rate through the square-edge orifice is predicted to be 5 percent greater than the flow rate budgeted in the engine balance. Since CFD predictions for LO2 and LH2 square-edge orifice pressure loss coefficients, K, both agree with published data, the equation for K has been used to define a procedure for orifice sizing.

  16. Investigation of the sound generation mechanisms for in-duct orifice plates.

    PubMed

    Tao, Fuyang; Joseph, Phillip; Zhang, Xin; Stalnov, Oksana; Siercke, Matthias; Scheel, Henning

    2017-08-01

    Sound generation due to an orifice plate in a hard-walled flow duct which is commonly used in air distribution systems (ADS) and flow meters is investigated. The aim is to provide an understanding of this noise generation mechanism based on measurements of the source pressure distribution over the orifice plate. A simple model based on Curle's acoustic analogy is described that relates the broadband in-duct sound field to the surface pressure cross spectrum on both sides of the orifice plate. This work describes careful measurements of the surface pressure cross spectrum over the orifice plate from which the surface pressure distribution and correlation length is deduced. This information is then used to predict the radiated in-duct sound field. Agreement within 3 dB between the predicted and directly measured sound fields is obtained, providing direct confirmation that the surface pressure fluctuations acting over the orifice plates are the main noise sources. Based on the developed model, the contributions to the sound field from different radial locations of the orifice plate are calculated. The surface pressure is shown to follow a U 3.9 velocity scaling law and the area over which the surface sources are correlated follows a U 1.8 velocity scaling law.

  17. A pulse-tube refrigerator using variable-resistance orifice

    NASA Astrophysics Data System (ADS)

    Huang, B. J.; Sun, B. W.

    2003-01-01

    In the present study, we propose a new design of orifice pulse-tube refrigerator (VROPT) using a variable-resistance valve to replace the conventional orifice. The variable-resistance orifice (VRO) is basically a high-speed solenoidal valve similar to the fuel jet device widely used in automobile engines. By changing the frequency and periods of ON and OFF of the valve through an electronic device, we can change the flow resistance of the VRO. This thus provides a possibility for an OPT to be controlled on-line during operation. From the results obtained in the present study, we have shown that VROPT is able to achieve on-line control by regulating the duty cycle d or frequency fv of the VRO. We also show that VROPT will not loss its thermal performance as compared to conventional OPT.

  18. The Impact of Manifold-to-Orifice Turning Angle on Sharp-Edge Orifice Flow Characteristics in both Cavitation and Non-Cavitation Turbulent Flow Regimes (Preprint)

    DTIC Science & Technology

    2007-06-01

    varies as the cavitation number is lowered. The third is supercavitation where the vapor pocket attachment has moved to the orifice exit and beyond but...the flow still acts as attached. For this study only the 90 degree orifice angle configuration experienced supercavitation . For all other angles

  19. Ice/water slurry blocking phenomenon at a tube orifice.

    PubMed

    Hirochi, Takero; Yamada, Shuichi; Shintate, Tuyoshi; Shirakashi, Masataka

    2002-10-01

    The phenomenon of ice-particle/water mixture blocking flow through a pipeline is a problem that needs to be solved before mixture flow can be applied for practical use in cold energy transportation in a district cooling system. In this work, the blocking mechanism of ice-particle slurry at a tube orifice is investigated and a criterion for blocking is presented. The cohesive nature of ice particles is shown to cause compressed plug type blocking and the compressive yield stress of a particle cluster is presented as a measure for the cohesion strength of ice particles.

  20. Chevron facility focused on commercial orifice-meter research

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Jones, E.H.; Ferguson, K.R.

    1987-07-27

    Research to determine the accuracy of commercial orifice meters for custody-transfer measurement has indicated that high-volume gas meters can be flow-proven while in such service. The research further yielded more accurate orifice-meter discharge coefficient equations (at Reynolds numbers greater than 4,000,000) than current equations of the International Standards Organization (ISO) and the American Petroleum Institute (API). These are partial findings of a major study conducted by Chevron Oil Field Research Co. at its Venice, La., calibration facility.

  1. Pure retroperitoneal natural orifice translumenal endoscopic surgery (NOTES) transvaginal nephrectomy using standard laparoscopic instruments: a safety and feasibility study in a porcine model.

    PubMed

    Wei, Dechao; Han, Yili; Li, Mingchuan; Wang, Yongxing; Chen, Yatong; Luo, Yong; Jiang, Yongguang

    2016-06-11

    Among the different organs used for NOTES (natural orifice translumenal endoscopic surgery) technique, the transvaginal approach may be the optimal choice because of a simple and secure closure of colpotomy site. Pure and hybrid NOTES transvaginal operations were routinely performed via transperitoneal access. In this study, we investigate the safety and feasibility of pure retroperitoneal natural orifice translumenal endoscopic surgery (NOTES) transvaginal nephrectomy using conventional laparoscopic techniques in a porcine model. Six female pigs, weighing an average of 30 kg, were used in this study. Under general anesthesia, pure retroperitoneal NOTES transvaginal nephrectomy was conducted using standard laparoscopic instruments. Posterolateral colpotomy was performed, and the incision was enlarged laterally using blunt dissection and pneumatic dilation. A single-port device was inserted to construct the operative channel. The retroperitoneal space was created using sharp and blunt dissection under endoscopic guidance up to the level of the kidney. Dissection and removal of the kidney were performed according to standard surgical procedure, and the colpotomy site was closed using interrupted sutures. The survival and complications were observed 1 week postoperatively. Our results showed that two cases failed because of peritoneal rupture. One case was successful, but required the assistance of an extra 5 mm laparoscopic trocar inserted in the flank. Three cases of pure retroperitoneal NOTES transvaginal nephrectomy were completed, and survived 1 week after the operation. In these three cases, no intra- or postoperative complications were observed. All findings confirmed the safety and feasibility of the retroperitoneal pure retroperitoneal NOTES transvaginal nephrectomy using standard laparoscopic instruments, which suggested the possibility of clinical application in human beings in the future.

  2. Orifice plate for controlling solids flow, methods of use thereof and articles comprising the same

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Jukkola, Glen D.; Teigen, Bard C.

    Disclosed herein is an orifice plate comprising one or more plates having orifices disposed therein; the orifices being operative to permit the flow of solids from a moving bed heat exchanger to a solids flow control system; where the orifice plate is downstream of a tube bundle of the moving bed heat exchanger and upstream of the solids flow control system and wherein the orifice plate is operative to evenly distribute the flow of solids in the solids flow control system.

  3. Acoustic Absorption Characteristics of an Orifice With a Mean Bias Flow

    NASA Technical Reports Server (NTRS)

    Ahuja, K. K.; Gaeta, R. J., Jr.; DAgostino, M.; Jones, Mike (Technical Monitor)

    2000-01-01

    The objective of the study reported here was to acquire acoustic and flow data for numerical validation of impedance models that simulate bias flow through perforates. The impedance model is being developed by researchers at High Technology Corporation. This report documents normal incidence impedance measurements a singular circular orifice with mean flow passing through it. All measurements are made within a 1.12 inch (28.5 mm) diameter impedance tube. The mean flow is introduced upstream of the orifice (with the flow and incident sound wave travelling in the same direction) with an anechoic termination downstream of the orifice. Velocity profiles are obtained upstream of the orifice to characterize the inflow boundary conditions. Velocity in the center of the orifice is also obtained. All velocity measurements are made with a hot wire anemometer and subsequent checked with mass flow measurements made concurrently. All impedance measurements are made using the Two-Microphone Method. Although we have left the analysis of the data to the developers of the impedance models that simulate bias flow through perforate, our initial examination indicates that our results follow the trends consistent with published theory on impedance of perforates with a steady bias flow.

  4. Apparatus and process for depositing hard coating in a nozzle orifice

    DOEpatents

    Flynn, P.L.; Giammarise, A.W.

    1994-12-20

    The present invention is directed to a process for coating the interior surfaces of an orifice in a substrate that forms a slurry fuel injection nozzle. In a specific embodiment, the nozzle is part of a fuel injection system for metering a coal-water slurry into a large, medium-speed, multi-cylinder diesel engine. In order to retard erosion of the orifice, the substrate is placed in a chemical vapor deposition (CVD) reaction chamber. A reaction gas is passed into the chamber at a gas temperature below its reaction temperature and is directed through the orifice in the substrate. The gas reaction temperature is a temperature at and above which the reaction gas deposits as a coating, and the reaction gas is of a composition whereby improved resistance to erosion by flow of the particulates in the slurry fuel is imparted by the deposited coating. Only the portion of the substrate in proximity to the orifice to be coated is selectively heated to at least the gas reaction temperature for effecting coating of the orifice's interior surfaces by the vapor deposited coating formed from the reaction gas. 2 figures.

  5. Apparatus and process for depositing hard coating in a nozzle orifice

    DOEpatents

    Flynn, Paul L.; Giammarise, Anthony W.

    1994-01-01

    The present invention is directed to a process for coating the interior surfaces of an orifice in a substrate that forms a slurry fuel injection nozzle. In a specific embodiment, the nozzle is part of a fuel injection system for metering a coal-water slurry into a large, medium-speed, multi-cylinder diesel engine. In order to retard erosion of the orifice, the substrate is placed in a chemical vapor deposition (CVD) reaction chamber. A reaction gas is passed into the chamber at a gas temperature below its reaction temperature and is directed through the orifice in the substrate. The gas reaction temperature is a temperature at and above which the reaction gas deposits as a coating, and the reaction gas is of a composition whereby improved resistance to erosion by flow of the particulates in the slurry fuel is imparted by the deposited coating. Only the portion of the substrate in proximity to the orifice to be coated is selectively heated to at least the gas reaction temperature for effecting coating of the orifice's interior surfaces by the vapor deposited coating formed from the reaction gas.

  6. Performance Evaluation of Steam Traps and Orifice Plates.

    DTIC Science & Technology

    1980-10-01

    ADlAO9dl 229 JOHNS - MANVILLE SALES CORP DENVER CO RESEARCH AND DEV-’ETC F/S 13/1 PERFOR1ANCE EVALUATION OF STEAM TRAPS AND ORIFICE PLATES.(U)/ OCT 80...AGENCY t REPORT FESA-TS-2085 41! PERFORMANCE EVALUATION OF STEAM TRAPS AND ORIFICE PLATES P. B. SHEPHERD JOHNS - MANVILLE SALES CORPORATION w RESEARCH...PERFORMING ORGANIZATION NAME ANED ADDPESS!_ i lFioC’iA.TCr ’.ETPlJ A~ Johns - Manville Sales Corporation &00* 0 - Research & Development Center qOll Ken

  7. The Double-Orifice Valve Technique to Treat Tricuspid Valve Incompetence.

    PubMed

    Hetzer, Roland; Javier, Mariano; Delmo Walter, Eva Maria

    2016-01-01

    A straightforward tricuspid valve (TV) repair technique was used to treat either moderate or severe functional (normal valve with dilated annulus) or for primary/organic (Ebstein's anomaly, leaflet retraction/tethering and chordal malposition/tethering, with annular dilatation) TV incompetence, and its long-term outcome assessed. A double-orifice valve technique was employed in 91 patients (mean age 52.6 ± 23.2 years; median age 56 years; range: 0.6-82 years) with severe tricuspid regurgitation. Among the patients, three had post-transplant iatrogenic chordal rupture, five had infective endocarditis, 11 had mitral valve insufficiency, 23 had Ebstein's anomaly, and 47 had isolated severe TV incompetence. The basic principle was to reduce the distance between the coapting leaflets, wherein the most mobile leaflet could coapt to the opposite leaflet, by creating two orifices, ensuring valve competence. The TV repair was performed through a median sternotomy or right anterior thoracotomy in the fifth intercostal space under cardiopulmonary bypass. The degree and extent of creating a double-valve orifice was determined by considering the minimal body surface area (BSA)-related acceptable TV diameter. Repair was accomplished by passing pledgeted mattress sutures from the middle of the true anterior annulus to a spot on the opposite septal annulus, located approximately two-thirds of the length of the septal annulus to avoid injury to the bundle of His. The annular apposition divides the TV into a larger anterior and a smaller posterior orifices, enabling valve closure, on both sides. In adults, the diameter of the anterior valve orifice should be 23-25 mm, and the posterior orifice 15-18 mm; thus, the total valve orifice area is 5-6 cm2. In children, the total valve orifice should be a standard deviation of 1.7 mm for a BSA of <1. 0m2, and 1.5 mm for a BSA of >1.0m2. During a mean follow up of 8.7 ± 1.34 years (median 10 years; range: 1.5-25.9 years) there have been no

  8. Video. Natural Orifice Translumenal Endoscopic Surgery with a miniature in vivo surgical robot.

    PubMed

    Lehman, Amy C; Dumpert, Jason; Wood, Nathan A; Visty, Abigail Q; Farritor, Shane M; Varnell, Brandon; Oleynikov, Dmitry

    2009-07-01

    The application of flexible endoscopy tools for Natural Orifice Translumenal Endoscopic Surgery (NOTES) is constrained due to limitations in dexterity, instrument insertion, navigation, visualization, and retraction. Miniature endolumenal robots can mitigate these constraints by providing a stable platform for visualization and dexterous manipulation. This video demonstrates the feasibility of using an endolumenal miniature robot to improve vision and to apply off-axis forces for task assistance in NOTES procedures. A two-armed miniature in vivo robot has been developed for NOTES. The robot is remotely controlled, has on-board cameras for guidance, and grasper and cautery end effectors for manipulation. Two basic configurations of the robot allow for flexibility during insertion and rigidity for visualization and tissue manipulation. Embedded magnets in the body of the robot and in an exterior surgical console are used for attaching the robot to the interior abdominal wall. This enables the surgeon to arbitrarily position the robot throughout a procedure. The visualization and task assistance capabilities of the miniature robot were demonstrated in a nonsurvivable NOTES procedure in a porcine model. An endoscope was used to create a transgastric incision and advance an overtube into the peritoneal cavity. The robot was then inserted through the overtube and into the peritoneal cavity using an endoscope. The surgeon successfully used the robot to explore the peritoneum and perform small-bowel dissection. This study has demonstrated the feasibility of inserting an endolumenal robot per os. Once deployed, the robot provided visualization and dexterous capabilities from multiple orientations. Further miniaturization and increased dexterity will enhance future capabilities.

  9. Diagnostic transgastric flexible peritoneoscopy: is pure natural orifice transluminal endoscopic surgery a fantasy?

    PubMed

    Hyder, Q; Zahid, M A; Ahmad, W; Rashid, R; Hadi, S F; Qazi, S; Haider, H K H

    2008-12-01

    We present the first transgastric peritoneoscopy in a 20-year-old man. The objectives were to evaluate the impact of the site of viscerotomy on the technical feasibility of natural orifice transluminal endoscopic surgery (NOTES), assess transgastric peritoneoscopy as a complementary procedure, determine the safety and efficacy of NOTES, and attempt inspection/biopsy of the gallbladder. The patient was admitted with a benign gastric outlet obstruction, chronic cholecystitis and radiological suspicion of a mass in the gallbladder which was not visualised on diagnostic laparoscopy. Complementary transgastric peritoneoscopy was performed to gain deeper penetration of the tumour with the flexible tip of the gastroscope. The visceral "aperture" was created in the antrum where gastrojejunal anastomosis would be fashioned. Laparoscopic transillumination of the anterior gastric wall facilitated this part of the procedure. During transgastric peritoneoscopy, the gallbladder and structures in the upper and left hemi-abdomen appeared retrograde due to the unusual location of the gastrotomy. The right hemi-abdomen and pelvis were easily examined with a "straight shaft" approach. The gallbladder could not be identified with exploratory laparoscopy and transgastric peritoneoscopy. Due to risk of visceral injury, open gastrojejunal anastomosis and cholecystectomy were performed. Intraoperatively, an inflamed, thick-walled gallbladder was found adherent to the proximal duodenum. Transgastric peritoneoscopy was safely performed in our patient. The postoperative course was uneventful. Our patient showed significant improvement at 13 weeks after surgery without any procedure-related complication. In conclusion, transgastric peritoneoscopy may be used to complement diagnostic laparoscopy. Laparoscopic assistance during transluminal access facilitates simple tasks inside the peritoneal cavity to be performed safely.

  10. Optimization of Orifice Geometry for Cross-Flow Mixing in a Cylindrical Duct

    NASA Technical Reports Server (NTRS)

    Kroll, J. T.; Sowa, W. A.; Samuelsen, G. S.

    1996-01-01

    Mixing of gaseous jets in a cross-flow has significant applications in engineering, one example of which is the dilution zone of a gas turbine combustor. Despite years of study, the design of the jet injection in combustors is largely based on practical experience. The emergence of NO(x) regulations for stationary gas turbines and the anticipation of aero-engine regulations requires an improved understanding of jet mixing as new combustor concepts are introduced. For example, the success of the staged combustor to reduce the emission of NO(x) is almost entirely dependent upon the rapid and complete dilution of the rich zone products within the mixing section. It is these mixing challenges to which the present study is directed. A series of experiments was undertaken to delineate the optimal mixer orifice geometry. A cross-flow to core-flow momentum-flux ratio of 40 and a mass flow ratio of 2.5 were selected as representative of a conventional design. An experimental test matrix was designed around three variables: the number of orifices, the orifice length-to- width ratio, and the orifice angle. A regression analysis was performed on the data to arrive at an interpolating equation that predicted the mixing performance of orifice geometry combinations within the range of the test matrix parameters. Results indicate that the best mixing orifice geometry tested involves eight orifices with a long-to-short side aspect ratio of 3.5 at a twenty-three degree inclination from the center-line of the mixing section.

  11. Effect of Intra-Orifice Depth on Sealing Ability of Four Materials in the Orifices of Root-Filled Teeth: An Ex-Vivo Study

    PubMed Central

    Ghulman, Motaz Ahmad; Gomaa, Madiha

    2012-01-01

    Aim. To investigate the effect of orifice cavity depth on the sealing ability of Fusio, Fuji II, Fuji IX, and MTA“G”. Materials and Methods. Ninety-two canals in extracted mandibular premolars were prepared, obturated, and randomly grouped into 4 groups. Each group was subgrouped for a 2 mm and 3 mm orifice cavity depth (n = 10). The remaining roots were divided to serve as positive and negative controls (n = 6). Cavities of the 4 experimental groups were filled with the respective materials and subjected to methylene blue dye leakage. Linear leakage was measured in mm using a stereomicroscope. Statistical Analysis. Kruskall-Wallis test was used at P < 0.05, and t-test was done to compare 2 mm and 3 mm. Results. All tested materials leaked to various degrees. Significantly higher leakage score was found for Fuji IX, Fusio, Fuji II, and MTA “G” in a descending order, when the materials were placed at 3 mm depths. A significant difference was found in the leakage score between the 2 mm and 3 mm depths in all tested materials with the 3 mm depth showing a greater leakage score in all tested materials. Exception was in MTA “G” at 2 mm and 3 mm depths (0.551 mm ± 0.004 mm and 0.308 mm ± 0.08 mm, resp.). Conclusion. The null hypothesis should be partially rejected. Fusio and MTA “G” were affected by orifice cavity depth with regard to their sealing ability. MTA “G” had the least leakage when placed at 2 or 3 mm depths, and Fusio is the next when placed at 2 mm depth. Two millimeters orifice cavity depth is suitable for most adhesive orifice barrier materials. PMID:22675356

  12. Spectral characterization of natural backgrounds

    NASA Astrophysics Data System (ADS)

    Winkelmann, Max

    2017-10-01

    As the distribution and use of hyperspectral sensors is constantly increasing, the exploitation of spectral features is a threat for camouflaged objects. To improve camouflage materials at first the spectral behavior of backgrounds has to be known to adjust and optimize the spectral reflectance of camouflage materials. In an international effort, the NATO CSO working group SCI-295 "Development of Methods for Measurements and Evaluation of Natural Background EO Signatures" is developing a method how this characterization of backgrounds has to be done. It is obvious that the spectral characterization of a background will be quite an effort. To compare and exchange data internationally the measurements will have to be done in a similar way. To test and further improve this method an international field trial has been performed in Storkow, Germany. In the following we present first impressions and lessons learned from this field campaign and describe the data that has been measured.

  13. Background radiation: natural and man-made.

    PubMed

    Thorne, M C

    2003-03-01

    A brief overview and comparison is given of dose rates arising from natural background radiation and the fallout from atmospheric testing of nuclear weapons. Although there are considerable spatial variations in exposure to natural background radiation, it is useful to give estimates of worldwide average overall exposures from the various components of that background. Cosmic-ray secondaries of low linear energy transfer (LET), mainly muons and photons, deliver about 280 microSv a(-1). Cosmic-ray neutrons deliver about another 100 microSv a(-1). These low- and high-LET exposures are relatively uniform to the whole body. The effective dose rate from cosmogenic radionuclides is dominated by the contribution of 12 microSv a(-1) from 14C. This is due to relatively uniform irradiation of all organs and tissues from low-energy beta particles. Primordial radionuclides and their progeny (principally the 238U and 232Th series, and 40K) contribute about 480 microSv a(-1) of effective dose by external irradiation. This is relatively uniform photon irradiation of the whole body. Internally incorporated 40K contributes a further 165 microSv a(-1) of effective dose in adults, mainly from beta particles, but with a significant gamma component. Equivalent doses from 40K are somewhat higher in muscle than other soft tissues, but the distinction is less than a factor of three. Uranium and thorium series radionuclides give rise to an average effective dose rate of around 120 microSv a(-1). This includes a major alpha particle component, and exposures of radiosensitive tissues in lung, liver, kidney and the skeleton are recognised as important contributors to effective dose. Overall, these various sources give a worldwide average effective dose rate of about 1160 microSv a(-1). Exposure to 222Rn, 220Rn and their short-lived progeny has to be considered separately. This is very variable both within and between countries. For 222Rn and its progeny, a worldwide average effective dose

  14. An Experimental Study of Synthetic Jets from Rectangular Orifices

    NASA Technical Reports Server (NTRS)

    Milanovic, Ivana M.

    2003-01-01

    During the past two summers Professor Milanovic conducted Wind tunnel experiments on steady jets-in-cross-flow and synthetic jets. In her anticipated visit during the upcoming summer, she will continue and complete the research on synthetic jets involving 2-dimensional orifices of different aspect ratio as well as inclined slots. In addition, experiments will be conducted on pulsatile jets-in-cross-flow. The pulsation will be provided via an oscillating valve at controllable frequencies. The experiment will involve mainly hot-wire anemometer measurements in the low-speed wind tunnel. Overall goal will be to obtain database and investigate flow control strategies. The research will be of fundamental nature.

  15. Orifice Mass Flow Calculation in NASA's W-8 Single Stage Axial Compressor Facility

    NASA Technical Reports Server (NTRS)

    Bozak, Richard F.

    2018-01-01

    Updates to the orifice mass flow calculation for the W-8 Single Stage Axial Compressor Facility at NASA Glenn Research Center are provided to include the effect of humidity and incorporate ISO 5167. A methodology for including the effect of humidity into the inlet orifice mass flow calculation is provided. Orifice mass flow calculations provided by ASME PTC-19.5-2004, ASME MFC-3M-2004, ASME Fluid Meters, and ISO 5167 are compared for W-8's atmospheric inlet orifice plate. Differences in expansion factor and discharge coefficient given by these standards give a variation of about +/- 75% mass flow except for a few cases. A comparison of the calculations with an inlet static pressure mass flow correlation and a fan exit mass flow integration using test data from a 2017 turbofan rotor test in W-8 show good agreement between the inlet static pressure mass flow correlation, ISO 5167, and ASME Fluid Meters. While W-8's atmospheric inlet orifice plate violates the pipe diameter limit defined by each of the standards, the ISO 5167 is chosen to be the primary orifice mass flow calculation to use in the W-8 facility.

  16. Preparation of spherical particles by vibrating orifice technique

    NASA Astrophysics Data System (ADS)

    Shibata, Shuichi; Tomizawa, Atsushi; Yoshikawa, Hidemi; Yano, Tetsuji; Yamane, Masayuki

    2000-05-01

    Preparation of micrometer-sized spherical particles containing Rhodamine 6G (R6G) has been investigated for the spherical cavity micro-laser. Using phenyl triethoxy silane (PTES) as a starting material, R6G-doped monodisperse spherical particles were prepared by the vibrating orifice technique. Processing consists of two major processes: (1) Hydrolysis and polymerization of PTES and (2) Droplet formation from PTES oligomers by vibrating orifice technique. A cylindrical liquid jet passing through the orifice of 10 and 20 micrometers in diameter breaks up into equal- sized droplets by mechanical vibration. Alcohol solvent of these droplets was evaporated during flying with carrier gas and subsequently solidified in ammonium water trap. For making smooth surface and god shaped particles, control of molecular weight of PTES oligomer was essential. R6G-doped hybrid spherical particles of 4 to 10 micrometers size of cavity structure were successfully obtained. The spherical particles were pumped by a second harmonic pulse of Q- switched Nd:YAG laser and laser emission peaks were observed at wavelengths which correspond to the resonance modes.

  17. [Fourth branchial cleft deformity with skin orifice: a series of 10 cases].

    PubMed

    Huang, S L; Zhang, B; Chen, L S; Liang, L; Luo, X N; Lu, Z M; Zhang, S Y

    2016-10-07

    Objective: To report rare cases of congenital neck cutaneous sinus with an orifice near the sternoclavicular joint and to investigate their origins and managements. Methods: A total of ten patients with congenital neck cutaneous sinus having an orifice near the sternoclavicular joint treated in the Guangdong General Hospital from January 2010 to June 2015 were retrospectively analyzed. Results: There four boys and six girls, aging from 11 months to 96 months with an average of 33.4 months, and they had a common feature showing a congenital cutaneous sinus with an orifice near sternoclavicular joint. Discharge of pus from the orifice or abscess formation was commonly seen soon after infection. With bacteriological study, staphylococcus aureus was positive in five cases and klebsiella pneumonia in a case. Another orifice of fistula/sinus was not depicted in pyriform with barium swallow X-ray in five cases Ultrasound studies of three cases demonstrated anechoic (i.e., nearly black) and solid-cystic lesion near sternoclavicular joint with posterior acoustic enhancement. Magnetic resonance imaging (MRI) showed isointensity of the lesion on T1 and T2 weighted images with heterogeneous enhancement and a close relationship with sternoclavicular joint. All patients underwent laryngoscopic examination, which showed no orifice of sinus in pyriform at same side. Surgical resection of fistula/sinus was performed in all cases. The lengths of the fistula varied from 5 mm to 22 mm with an average of 11 mm. Postoperative pathological examination showed all specimens were accordance with fistula. No complications were noticed. Recurrence was not observed in the cases by following-up of 6 months to 70 months (median: 33 months). Conclusion: Congenital neck cutaneous sinus with orifice near the sternoclavicular joint maybe a special clinical phenotype of the fourth branchial cleft sinus with skin orifice in cervicothoracic junction. Differential diagnoses between low cervical diseases

  18. Head loss coefficient through sharp-edged orifices

    NASA Astrophysics Data System (ADS)

    Adam, Nicolas J.; De Cesare, Giovanni; Schleiss, Anton J.; Richard, Sylvain; Muench-Alligné, Cécile

    2016-11-01

    Nowadays, high-head power plants could increase their installed power capacity for many reasons, e.g. dam heightening, increase of their peak power capacity or refurbishment with new turbines. Frequently, due to several considerations, e.g. topographical or economical limitations, the existing surge tank cannot be extended to keep previous safety levels and efficiency. A valuable way to adapt these surge tanks is to place a throttle at their entrance like, for example, an orifice. The main effect of this adaptation is the introduction of head losses that reduce the extreme levels in the surge tank due to the mass oscillations resulting from a closure or opening of downstream discharge control. This research studies the influence of the edge angle of a ASME-standard orifice on the head losses. This angle introduces an asymmetrical behavior and influences head losses. Different angles are tested from 0° to the 67° (biggest angle possible for this configuration). The first step of this study is to determine experimentally the steady losses produced by orifice for several discharges. In the second step, a numerical model on ANSYS CFX is performed. Combining the two approaches, it is possible to understand and quantify the effect of the edge angle.

  19. Double-orifice mitral valve associated with bicuspid aortic valve.

    PubMed

    Khani, Mohammad; Rohani, Atoosheh

    2017-06-01

    Double-orifice mitral valve is a rare congenital anomaly that usually does not cause a significant hemodynamic effect. Double-orifice mitral valve and a bicuspid aortic valve were detected in a 54-year-old lady who presented with dyspnea on exertion for one year. This is a rare association. Three-dimensional echocardiography is helpful to determine the type of malformation. The patient had no significant mitral regurgitation or stenosis, but demonstrated moderate aortic stenosis. She is undergoing periodic monitoring.

  20. In-flight investigation of shuttle tile pressure orifice installations

    NASA Technical Reports Server (NTRS)

    Moes, Timothy R.; Meyer, Robert R., Jr.

    1990-01-01

    To determine shuttle orbiter wing loads during ascent, wing load instrumentation was added to Columbia (OV-102). This instrumentation included strain gages and pressure orifices on the wing. The loads derived from wing pressure measurements taken during STS 61-C did not agree with those derived from strain gage measurements or with the loads predicted from the aerodynamic database. Anomalies in the surface immediately surrounding the pressure orifices in the thermal protection system (TPS) tiles were one possible cause of errors in the loads derived from wing pressure measurements. These surface anomalies were caused by a ceramic filler material which was installed around the pressure tubing. The filler material allowed slight movement of the TPS tile and pressure tube as the airframe flexed and bent under aerodynamic loads during ascent and descent. Postflight inspection revealed that this filler material had protruded from or receeded beneath the surface, causing the orifice to lose its flushness. Flight tests were conducted at NASA Ames Research Center Dryden Flight Research Facility to determine the effects of any anomaly in surface flushness of the orifice installation on the measured pressures at Mach numbers between 0.6 and 1.4. An F-104 aircraft with a flight test fixture mounted beneath the fuselage was used for these flights. Surface flushness anomalies typical of those on the orbiter after flight (STA 61-C) were tested. Also, cases with excessive protrusion and recession of the filler material were tested. This report shows that the anomalies in STS 61-C orifice installations adversely affected the pressure measurements. But the magnitude of the affect was not great enough to account for the discrepancies with the strain gage measurements and the aerodynamic predictions.

  1. Flow rate of some pharmaceutical diluents through die-orifices relevant to mini-tableting.

    PubMed

    Kachrimanis, K; Petrides, M; Malamataris, S

    2005-10-13

    The effects of cylindrical orifice length and diameter on the flow rate of three commonly used pharmaceutical direct compression diluents (lactose, dibasic calcium phosphate dihydrate and pregelatinised starch) were investigated, besides the powder particle characteristics (particle size, aspect ratio, roundness and convexity) and the packing properties (true, bulk and tapped density). Flow rate was determined for three different sieve fractions through a series of miniature tableting dies of different orifice diameter (0.4, 0.3 and 0.2 cm) and thickness (1.5, 1.0 and 0.5 cm). It was found that flow rate decreased with the increase of the orifice length for the small diameter (0.2 cm) but for the large diameter (0.4 cm) was increased with the orifice length (die thickness). Flow rate changes with the orifice length are attributed to the flow regime (transitional arch formation) and possible alterations in the position of the free flowing zone caused by pressure gradients arising from the flow of self-entrained air, both above the entrance in the die orifice and across it. Modelling by the conventional Jones-Pilpel non-linear equation and by two machine learning algorithms (lazy learning, LL, and feed-forward back-propagation, FBP) was applied and predictive performance of the fitted models was compared. It was found that both FBP and LL algorithms have significantly higher predictive performance than the Jones-Pilpel non-linear equation, because they account both dimensions of the cylindrical die opening (diameter and length). The automatic relevance determination for FBP revealed that orifice length is the third most influential variable after the orifice diameter and particle size, followed by the bulk density, the difference between bulk and tapped densities and the particle convexity.

  2. In vivo miniature robots for natural orifice surgery: State of the art and future perspectives.

    PubMed

    Tiwari, Manish M; Reynoso, Jason F; Lehman, Amy C; Tsang, Albert W; Farritor, Shane M; Oleynikov, Dmitry

    2010-06-27

    Natural orifice translumenal endoscopic surgery (NOTES) is the integration of laparoscopic minimally invasive surgery techniques with endoscopic technology. Despite the advances in NOTES technology, the approach presents several unique instrumentation and technique-specific challenges. Current flexible endoscopy platforms for NOTES have several drawbacks including limited stability, triangulation and dexterity, and lack of adequate visualization, suggesting the need for new and improved instrumentation for this approach. Much of the current focus is on the development of flexible endoscopy platforms that incorporate robotic technology. An alternative approach to access the abdominal viscera for either a laparoscopic or NOTES procedure is the use of small robotic devices that can be implanted in an intracorporeal manner. Multiple, independent, miniature robots can be simultaneously inserted into the abdominal cavity to provide a robotic platform for NOTES surgery. The capabilities of the robots include imaging, retraction, tissue and organ manipulation, and precise maneuverability in the abdominal cavity. Such a platform affords several advantages including enhanced visualization, better surgical dexterity and improved triangulation for NOTES. This review discusses the current status and future perspectives of this novel miniature robotics platform for the NOTES approach. Although these technologies are still in pre-clinical development, a miniature robotics platform provides a unique method for addressing the limitations of minimally invasive surgery, and NOTES in particular.

  3. Contoured Orifice for Silicon-Ribbon Die

    NASA Technical Reports Server (NTRS)

    Mackintosh, B. H.

    1985-01-01

    Die configuration encourages purity and stable growth. Contour of die orifice changes near ribbon edges. As result, silicon ribbon has nearly constant width and little carbon contamination. Die part of furnace being developed to produce high-quality, low-cost material for solar cells.

  4. Parametric measurements of the effect of in-duct orifice edge shape on its noise damping performance

    NASA Astrophysics Data System (ADS)

    Ji, Chenzhen; Zhao, Dan; Han, Nuomin; Li, Jing

    2016-12-01

    Acoustic liners perforated with thousands of millimeter-size orifices are widely used in aero-engines and gas turbine engines as an effective noise damper. In this work, experimental investigations of the acoustic damping effect of in-duct perforated orifices are performed on a cold-flow pipe. A mean flow (also known as bias flow) is applied and its flow rate is variable. Emphasis is placed on the effect of the orifice edge shape. For this, 16 in-duct orifices with different edge shapes and porosities are designed and manufactured by using 3D printing technology and conventional laser cutting technique. The damping effect of these in-duct orifices is characterized by using power absorption coefficient Δ and reflection coefficient χ from 100 to 1000 Hz. The performances of these orifices are found to be either improved or deteriorated, depending on (1) edge shape, (2) the ratio T/d of orifice thickness to its diameter, (3) the bias flow Mach number, (4) downstream pipe length Ld and (5) porosity η via varying either the number N or surface area Ao of the orifices. In addition, modifying orifice edge does not lead to an increase of power absorption at lower frequency (⩽ 700 Hz). However, as the frequency is increased, the orifice with square (S-type) edge is found to be associated with 10 percent more power absorption. It is interesting to find that T/d over the tested range (≤ 0.5) has little influence on its damping capacity. However, the mean bias flow Mach number Ma and porosity η are shown to play critical roles on determining the noise damping performance of these orifices. Maximum power absorption Δmax is found to occur at Ma ≈ 0.018, while the optimum porosity corresponding to Δmax is approximately 7 percent. The present parametric measurements shed light on the roles of orifice edge shape, porosity and mean flow on its noise damping capacity, and facilitate the design of effective perforated liners.

  5. Acoustic response of a rectangular levitator with orifices

    NASA Technical Reports Server (NTRS)

    El-Raheb, Michael; Wagner, Paul

    1990-01-01

    The acoustic response of a rectangular cavity to speaker-generated excitation through waveguides terminating at orifices in the cavity walls is analyzed. To find the effects of orifices, acoustic pressure is expressed by eigenfunctions satisfying Neumann boundary conditions as well as by those satisfying Dirichlet ones. Some of the excess unknowns can be eliminated by point constraints set over the boundary, by appeal to Lagrange undetermined multipliers. The resulting transfer matrix must be further reduced by partial condensation to the order of a matrix describing unmixed boundary conditions. If the cavity is subjected to an axial temperature dependence, the transfer matrix is determined numerically.

  6. Investigation of orifice aeroacoustics by means of multi-port methods

    NASA Astrophysics Data System (ADS)

    Sack, Stefan; Åbom, Mats

    2017-10-01

    Comprehensive methods to cascade active multi-ports, e.g., for acoustic network prediction, have until now only been available for plane waves. This paper presents procedures to combine multi-ports with an arbitrary number of considered duct modes. A multi-port method is used to extract complex mode amplitudes from experimental data of single and tandem in-duct orifice plates for Helmholtz numbers up to around 4 and, hence, beyond the cut-on of several higher order modes. The theory of connecting single multi-ports to linear cascades is derived for the passive properties (the scattering of the system) and the active properties (the source cross-spectrum matrix of the system). One scope of this paper is to investigate the influence of the hydrodynamic near field on the accuracy of both the passive and the active predictions in multi-port cascades. The scattering and the source cross-spectrum matrix of tandem orifice configurations is measured for three cases, namely, with a distance between the plates of 10 duct diameter, for which the downstream orifice is outside the jet of the upstream orifice, 4 duct diameter, and 2 duct diameter (both inside the jet). The results are compared with predictions from single orifice measurements. It is shown that the scattering is only sensitive to disturbed inflow in certain frequency ranges where coupling between the flow and sound field exists, whereas the source cross-spectrum matrix is very sensitive to disturbed inflow for all frequencies. An important part of the analysis is based on an eigenvalue analysis of the scattering matrix and the source cross-spectrum matrix to evaluate the potential of sound amplification and dominant source mechanisms.

  7. Experiments in dilution jet mixing effects of multiple rows and non-circular orifices

    NASA Technical Reports Server (NTRS)

    Holdeman, J. D.; Srinivasan, R.; Coleman, E. B.; Meyers, G. D.; White, C. D.

    1985-01-01

    Experimental and empirical model results are presented that extend previous studies of the mixing of single-sided and opposed rows of jets in a confined duct flow to include effects of non-circular orifices and double rows of jets. Analysis of the mean temperature data obtained in this investigation showed that the effects of orifice shape and double rows are significant only in the region close to the injection plane, provided that the orifices are symmetric with respect to the main flow direction. The penetration and mixing of jets from 45-degree slanted slots is slightly less than that from equivalent-area symmetric orifices. The penetration from 2-dimensional slots is similar to that from equivalent-area closely-spaced rows of holes, but the mixing is slower for the 2-D slots. Calculated mean temperature profiles downstream of jets from non-circular and double rows of orifices, made using an extension developed for a previous empirical model, are shown to be in good agreement with the measured distributions.

  8. Experiments in dilution jet mixing - Effects of multiple rows and non-circular orifices

    NASA Technical Reports Server (NTRS)

    Holdeman, J. D.; Srinivasan, R.; Coleman, E. B.; Meyers, G. D.; White, C. D.

    1985-01-01

    Experimental and empirical model results are presented that extend previous studies of the mixing of single-sided and opposed rows of jets in a confined duct flow to include effects of non-circular orifices and double rows of jets. Analysis of the mean temperature data obtained in this investigation showed that the effects of orifice shape and double rows are significant only in the region close to the injection plane, provided that the orifices are symmetric with respect to the main flow direction. The penetration and mixing of jets from 45-degree slanted slots is slightly less than that from equivalent-area symmetric orifices. The penetration from two-dimensional slots is similar to that from equivalent-area closely-spaced rows of holes, but the mixing is slower for the 2-D slots. Calculated mean temperature profiles downstream of jets from non-circular and double rows of orifices, made using an extension developed for a previous empirical model, are shown to be in good agreement with the measured distributions.

  9. Experimental Investigation of Cavitation Induced Feedline Instability from an Orifice

    NASA Technical Reports Server (NTRS)

    Hitt, Matthew A.; Lineberry, David M.; Ahuja, Vineet; Frederick, Robert A,

    2012-01-01

    This paper details the results of an experimental investigation into the cavitation instabilities created by a circular orifice conducted at the University of Alabama in Huntsville Propulsion Research Center. This experiment was conducted in concert with a computational simulation to serve as a reference point for the simulation. Testing was conducted using liquid nitrogen as a cryogenic propellant simulant. A 1.06 cm diameter thin orifice with a rounded inlet was tested in an approximately 1.25 kg/s flow with inlet pressures ranging from 504.1 kPa to 829.3 kPa. Pressure fluctuations generated by the orifice were measured using a high frequency pressure sensor located 0.64 tube diameters downstream of the orifice. Fast Fourier Transforms were performed on the high frequency data to determine the instability frequency. Shedding resulted in a primary frequency with a cavitation related subharmonic frequency. For this experiment, the cavitation instability ranged from 153 Hz to 275 Hz. Additionally, the strength of the cavitation occur red as a function of cavitation number. At lower cavitation numbers, the strength of the cavitation instability ranged from 2.4 % to 7 % of the inlet pressure. However, at higher cavitation numbers, the strength of the cavitation instability ranged from 0.6 % to 1 % of the inlet pressure.

  10. New laser soldering-based closures: a promising method in natural orifice transluminal endoscopic surgery.

    PubMed

    Bogni, Serge; Ortner, Maria-Anna; Vajtai, Istvan; Jost, Christian; Reinert, Michael; Dallemagne, Bernard; Frenz, Martin

    2012-07-01

    Complete closure of gastrotomy is the linchpin of safe natural orifice transgastric endoscopic surgery. To evaluate feasibility and efficacy of a new method of gastrotomy closure by using a sutureless laser tissue-soldering (LTS) technique in an ex vivo porcine stomach. In vitro experiment. Experimental laboratory. Histological analysis and internal and external liquid pressure with and without hydrochloric acid exposure were determined comparing gastrotomy closure with LTS and with hand-sewn surgical sutures. Comparison of LTS and hand-sewn surgical gastrotomy closure. The primary outcome parameter was the internal leak pressure. Secondary parameters were the difference between internal and external leak pressures, the impact of an acid environment on the device, histological changes, and feasibility of endoscopic placement. The internal liquid leak pressure after LTS was almost twice as high as after hand-sewn surgical closure (416 ± 53 mm Hg vs 229 ± 99 mm Hg; P = .01). The internal leak pressure (416 ± 53 mm Hg) after LTS was higher than the external leak pressure (154 ± 46 mm Hg; P < .0001). An acidic environment did not affect leak pressure after LTS. Endoscopic LTS closure was feasible in all experiments. Histopathology revealed only slight alterations beneath the soldering plug. In vitro experiments. Leak pressure after LTS closure of gastrotomy is higher than after hand-sewn surgical closure. LTS is a promising technique for closure of gastrotomies and iatrogenic perforations. Further experiments, in particular survival studies, are mandatory. Copyright © 2012 American Society for Gastrointestinal Endoscopy. Published by Mosby, Inc. All rights reserved.

  11. Variable orifice using an iris shutter

    DOEpatents

    Beeman, Raymond; Brajkovich, Steven J.

    1978-01-01

    A variable orifice forming mechanism utilizing an iris shutter arrangement adapted to control gas flow, conductance in vacuum systems, as a heat shield for furnace windows, as a beam shutter in sputtering operations, and in any other application requiring periodic or continuously-variable control of material, gas, or fluid flow.

  12. Effects of Orifice-Weir Outlet on Hydrology and Water Quality of a Drained Forested Watershed

    Treesearch

    Devendra M. Amatya; R. Wayne Skaggs; J.W. Gilliam; J.H. Hughes

    2003-01-01

    Orifice-weir structures at ditch outlets are proposed to reduce peak drainage rates during high flows and to store water during the growing season in poorly drained managed pine plantations. Two coastal watersheds, one conventionally drained (D1) and another with an orifice-weir outlet (D3), were monitored to examine the effects of this orifice treatment on drainage...

  13. Sinning against nature: the theory of background conditions

    PubMed Central

    Blackford, R

    2006-01-01

    Debates about the moral and political acceptability of particular sexual practices and new technologies often include appeals to a supposed imperative to follow nature. If nature is understood as the totality of all phenomena or as those things that are not artificial, there is little prospect of developing a successful argument to impugn interference with it or sinning against it. At the same time, there are serious difficulties with approaches that seek to identify "proper" human functioning. An alternative approach is to understand interference with nature as acting in a manner that threatens basic background conditions to human choice. Arguably, the theory of background conditions helps explain much of the hostility to practices and technologies that allegedly sin against nature. The theory does not, however, entail that appeals to nature are relevant or rational. Such appeals should be subjected to sceptical scrutiny. Indeed, the theory suggests that arguments against practices and technologies that can be seen as contrary to nature sometimes exercise a psychological attraction that is disproportional to their actual cogency. PMID:17074819

  14. ETF Facility evaporator skid orifice sizing design analysis

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    ELLINGSON, S.D.

    1999-08-31

    This document releases and records the design analysis for sizing the Orifice plate being installed on the Effluent Treatment Facility (ETF) evaporator skid per Engineering Change Notice (ECN) 651583.

  15. Gaseous Nitrogen Orifice Mass Flow Calculator

    NASA Technical Reports Server (NTRS)

    Ritrivi, Charles

    2013-01-01

    The Gaseous Nitrogen (GN2) Orifice Mass Flow Calculator was used to determine Space Shuttle Orbiter Water Spray Boiler (WSB) GN2 high-pressure tank source depletion rates for various leak scenarios, and the ability of the GN2 consumables to support cooling of Auxiliary Power Unit (APU) lubrication during entry. The data was used to support flight rationale concerning loss of an orbiter APU/hydraulic system and mission work-arounds. The GN2 mass flow-rate calculator standardizes a method for rapid assessment of GN2 mass flow through various orifice sizes for various discharge coefficients, delta pressures, and temperatures. The calculator utilizes a 0.9-lb (0.4 kg) GN2 source regulated to 40 psia (.276 kPa). These parameters correspond to the Space Shuttle WSB GN2 Source and Water Tank Bellows, but can be changed in the spreadsheet to accommodate any system parameters. The calculator can be used to analyze a leak source, leak rate, gas consumables depletion time, and puncture diameter that simulates the measured GN2 system pressure drop.

  16. Velocity field near the jet orifice of a round jet in a crossflow

    NASA Technical Reports Server (NTRS)

    Fearn, R. L.; Benson, J. P.

    1979-01-01

    Experimentally determined velocities at selected locations near the jet orifice are presented and analyzed for a round jet in crossflow. Jet-to-crossflow velocity ratios of four and eight were studied experimentally for a round subsonic jet of air exhausting perpendicularly through a flat plate into a subsonic crosswind of the same temperature. Velocity measurements were made in cross sections to the jet plume located from one to four jet diameters from the orifice. Jet centerline and vortex properties are presented and utilized to extend the results of a previous study into the region close to the jet orifice.

  17. Effect of grazing flow on the acoustic impedance of Helmholtz resonators consisting of single and clustered orifices

    NASA Technical Reports Server (NTRS)

    Hersch, A. S.; Walker, B.

    1979-01-01

    A semiempirical fluid mechanical model is derived for the acoustic behavior of thin-walled single orifice Helmholtz resonators in a grazing flow environment. The incident and cavity sound fields are connected in terms of an orifice discharge coefficient whose values are determined experimentally using the two-microphone method. Measurements show that at high grazing flow speeds, acoustical resistance is almost linearly proportional to the grazing flow speed and almost independent of incident sound pressure. The corresponding values of reactance are much smaller and tend towards zero. For thicker-walled orifice plates, resistance and reactance were observed to be less sensitive to grazing flow as the ratio of plate thickness to orifice diameter increased. Loud tones were observed to radiate from a single orifice Helmholtz resonator due to interaction between the grazing flow shear layer and the resonator cavity. Measurements showed that the tones radiated at a Strouhal number equal to 0.26. The effects of grazing flow on the impedance of Helmholtz resonators consisting of clusters of orifices was also studied. In general, both resistance and reaction were found to be virtually independent of orifice relative spacing and number. These findings are valid with and without grazing flow.

  18. A novel semi-automatic snake robot for natural orifice transluminal endoscopic surgery: preclinical tests in animal and human cadaver models (with video).

    PubMed

    Son, Jaebum; Cho, Chang Nho; Kim, Kwang Gi; Chang, Tae Young; Jung, Hyunchul; Kim, Sung Chun; Kim, Min-Tae; Yang, Nari; Kim, Tae-Yun; Sohn, Dae Kyung

    2015-06-01

    Natural orifice transluminal endoscopic surgery (NOTES) is an emerging surgical technique. We aimed to design, create, and evaluate a new semi-automatic snake robot for NOTES. The snake robot employs the characteristics of both a manual endoscope and a multi-segment snake robot. This robot is inserted and retracted manually, like a classical endoscope, while its shape is controlled using embedded robot technology. The feasibility of a prototype robot for NOTES was evaluated in animals and human cadavers. The transverse stiffness and maneuverability of the snake robot appeared satisfactory. It could be advanced through the anus as far as the peritoneal cavity without any injury to adjacent organs. Preclinical tests showed that the device could navigate the peritoneal cavity. The snake robot has advantages of high transverse force and intuitive control. This new robot may be clinically superior to conventional tools for transanal NOTES.

  19. 49 CFR 230.71 - Orifice testing of compressors.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Compressor size Single strokes per minute Diameter of orifice(in inches) Air pressure maintained(in pounds... feet the speed of compressor may be increased 5 single strokes per minute for each 1,000 feet increase...

  20. 49 CFR 230.71 - Orifice testing of compressors.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Compressor size Single strokes per minute Diameter of orifice(in inches) Air pressure maintained(in pounds... feet the speed of compressor may be increased 5 single strokes per minute for each 1,000 feet increase...

  1. 49 CFR 230.71 - Orifice testing of compressors.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Compressor size Single strokes per minute Diameter of orifice(in inches) Air pressure maintained(in pounds... feet the speed of compressor may be increased 5 single strokes per minute for each 1,000 feet increase...

  2. 49 CFR 230.71 - Orifice testing of compressors.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Compressor size Single strokes per minute Diameter of orifice(in inches) Air pressure maintained(in pounds... feet the speed of compressor may be increased 5 single strokes per minute for each 1,000 feet increase...

  3. 49 CFR 230.71 - Orifice testing of compressors.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Compressor size Single strokes per minute Diameter of orifice(in inches) Air pressure maintained(in pounds... feet the speed of compressor may be increased 5 single strokes per minute for each 1,000 feet increase...

  4. In-mine testing of a natural background sensor, part B

    NASA Technical Reports Server (NTRS)

    Martzloff, F. D.

    1981-01-01

    The capability of a natural background sensor for measuring the thickness of top coal on a longwall face was examined. The limitations on the time during which tests could be performed, and the roof conditions, did not produce readings of top coal measurements during the shearer operation. It was demonstrated that the system is capable to survive operating conditions in the mine environment, while the static tests confirmed that the natural background sensor approach is a valid method of measuring top coal thickness in mines where the roof rock provides a constant radiation level. It is concluded that the practical results will improve sequent development of an integrated vertical control system which is information from the natural background system.

  5. Bubble Formation at a Submerged Orifice in Reduced Gravity

    NASA Technical Reports Server (NTRS)

    Buyevich, Yu A.; Webbon, Bruce W.

    1994-01-01

    The dynamic regime of gas injection through a circular plate orifice into an ideally wetting liquid is considered, when successively detached bubbles may be regarded as separate identities. In normal gravity and at relatively low gas flow rates, a growing bubble is modeled as a spherical segment touching the orifice perimeter during the whole time of its evolution. If the flow rate exceeds a certain threshold value, another stage of the detachment process takes place in which an almost spherical gas envelope is connected with the orifice by a nearly cylindrical stem that lengthens as the bubble rises above the plate. The bubble shape resembles then that of a mushroom and the upper envelope continues to grow until the gas supply through the stem is completely cut off. Such a stage is always present under conditions of sufficiently low gravity, irrespective of the flow rate. Two major reasons make for bubble detachment: the buoyancy force and the force due to the momentum inflow into the bubble with the injected gas. The former force dominates the process at normal gravity whereas the second one plays a key role under negligible gravity conditions. It is precisely this fundamental factor that conditions the drastic influence on bubble growth and detachment that changes in gravity are able to cause. The frequency of bubble formation is proportional to and the volume of detached bubbles is independent of the gas flow rate in sufficiently low gravity, while at normal and moderately reduced gravity conditions the first variable slightly decreases and the second one almost linearly increases as the flow rate grows. Effects of other parameters, such as the orifice radius, gas and liquid densities, and surface tension are discussed.

  6. Cavitation in flow through a micro-orifice inside a silicon microchannel

    NASA Astrophysics Data System (ADS)

    Mishra, Chandan; Peles, Yoav

    2005-01-01

    Hydrodynamic cavitation in flows through a micro-orifice entrenched in a microchannel has been detected and experimentally investigated. Microfabrication techniques have been employed to design and develop a microfluidic device containing an 11.5μm wide micro-orifice inside a 100.2μm wide and 101.3μm deep microchannel. The flow of de-ionized water through the micro-orifice reveals the presence of multifarious cavitating flow regimes. This investigation divulges both similarities and differences between cavitation in micro-orifices and cavitation in their macroscale counterparts. The low incipient cavitation number obtained from the current experiments suggests a dominant size scale effect. Choking cavitation is observed to be independent of any pressure or velocity scale effects. However, choking is significantly influenced by the small stream nuclei residence time at such scales. Flow rate choking leads to the establishment of a stationary cavity. Large flow and cavitation hysteresis have been detected at the microscale leading to very high desinent cavitation numbers. The rapid transition from incipient bubbles to choking cavitation and subsequent supercavitation suggests the presence of radically different flow patterns at the microscale. Supercavitation results in a thick cavity, which extends throughout the microchannel, and is encompassed by the liquid. Cavitation at the microscale is expected to considerably influence the design of innovative high-speed microfluidic systems.

  7. Reduction of Secondary Flow in Inclined Orifice Pulse Tubes by Addition of DC Flow

    NASA Astrophysics Data System (ADS)

    Shiraishi, M.; Fujisawa, Y.; Murakami, M.; Nanako, A.

    2004-06-01

    The effect of using a second orifice valve to reduce convective losses caused by gravity-driven convective secondary flow in inclined orifice pulse tube refrigerators was investigated. The second orifice valve was installed between a reservoir and a low-pressure line of a compressor. When the valve was open, an additional DC flow directed to the hot end of the refrigerator was generated to counterbalance the convective secondary flow in the core region by opening the valve. Experimental results indicated that with increasing additional DC flow to an optimum level, the convective secondary flow decreased and the cooling performance improved, although further increase of the DC flow over the level caused the cooling performance to degrade. In summary, the second orifice valve was effective in reducing both the convective losses without affecting the cooling performance at an inclination angle < 70° where convective losses were negligibly small.

  8. Inactivation of Heterosigma akashiwo in ballast water by circular orifice plate-generated hydrodynamic cavitation.

    PubMed

    Feng, Daolun; Zhao, Jie; Liu, Tian

    2016-01-01

    The discharge of alien ballast water is a well-known, major reason for marine species invasion. Here, circular orifice plate-generated hydrodynamic cavitation was used to inactivate Heterosigma akashiwo in ballast water. In comparison with single- and multihole orifice plates, the conical-hole orifice plate yielded the highest inactivation percentage, 51.12%, and consumed only 6.84% energy (based on a 50% inactivation percentage). Repeating treatment, either using double series-connection or circling inactivation, elevated the inactivation percentage, yet consumed much more energy. The results indicate that conical-hole-generated hydrodynamic cavitation shows great potential as a pre-inactivation method for ballast water treatment.

  9. Mixing of Multiple Jets with a Confined Subsonic Crossflow. Part 2; Opposed Rows of Orifices in Rectangular Ducts

    NASA Technical Reports Server (NTRS)

    Holdeman, J. D.; Liscinsky, D. S.; Bain, D. B.

    1999-01-01

    This paper summarizes experimental and computational results on the mixing of opposed rows of jets with a confined subsonic crossflow in rectangular ducts. The studies from which these results were excerpted investigated flow and geometric variations typical of the complex three-dimensional flowfield in the combustion chambers in gas turbine engines. The principal observation was that the momentum-flux ratio, J, and the orifice spacing, S/H, were the most significant flow and geometric variables. Jet penetration was critical, and penetration decreased as either momentum-flux ratio or orifice spacing decreased. It also appeared that jet penetration remained similar with variations in orifice size, shape, spacing, and momentum-flux ratio when the orifice spacing was inversely proportional to the square-root of the momentum-flux ratio. It was also seen that planar averages must be considered in context with the distributions. Note also that the mass-flow ratios and the orifices investigated were often very large (jet-to-mainstream mass-flow ratio > 1 and the ratio of orifices-area-to-mainstream- cross-sectional-area up to 0.5, respectively), and the axial planes of interest were often just downstream of the orifice trailing edge. Three-dimensional flow was a key part of efficient mixing and was observed for all configurations.

  10. CFD Assessment of Orifice Aspect Ratio and Mass Flow Ratio on Jet Mixing in Rectangular Ducts

    NASA Technical Reports Server (NTRS)

    Bain, D. B.; Smith, C. E.; Holdeman, J. D.

    1994-01-01

    Isothermal CFD analysis was performed on axially opposed rows of jets mixing with cross flow in a rectangular duct. Laterally, the jets' centerlines were aligned with each other on the top and bottom walls. The focus of this study was to characterize the effects of orifice aspect ratio and jet-to-mainstream mass flow ratio on jet penetration and mixing. Orifice aspect ratios (L/W) of 4-to-1, 2-to-1, and 1-to-1, along with circular holes, were parametrically analyzed. Likewise, jet-to-mainstream mass flow ratios (MR) of 2.0, 0.5, and 0.25 were systematically investigated. The jet-to-mainstream momentum-flux ratio (J) was maintained at 36 for all cases, and the orifice spacing-to-duct height (S/H) was varied until optimum mixing was attained for each configuration. The numerical results showed that orifice aspect ratio (and likewise orifice blockage) had little effect on jet penetration and mixing. Based on mixing characteristics alone, the 4-to-1 slot was comparable to the circular orifice. The 4-to-1 slot has a smaller jet wake which may be advantageous for reducing emissions. However, the axial length of a 4-to-1 slot may be prohibitively long for practical application, especially for MR of 2.0. The jet-to-mainstream mass flow ratio had a more significant effect on jet penetration and mixing. For a 4-to-1 aspect ratio orifice, the design correlating parameter for optimum mixing (C = (S/H)(sq. root J)) varied from 2.25 for a mass flow ratio of 2.0 to 1.5 for a mass flow ratio of 0.25.

  11. Bubble Formation from Wall Orifice in Liquid Cross-Flow Under Low Gravity

    NASA Technical Reports Server (NTRS)

    Nahra, Henry K.; Kamotani, Y.

    2000-01-01

    Two-phase flows present a wide variety of applications for spacecraft thermal control systems design. Bubble formation and detachment is an integral part of the two phase flow science. The objective of the present work is to experimentally investigate the effects of liquid cross-flow velocity, gas flow rate, and orifice diameter on bubble formation in a wall-bubble injection configuration. Data were taken mainly under reduced gravity conditions but some data were taken in normal gravity for comparison. The reduced gravity experiment was conducted aboard the NASA DC-9 Reduced Gravity Aircraft. The results show that the process of bubble formation and detachment depends on gravity, the orifice diameter, the gas flow rate, and the liquid cross-flow velocity. The data are analyzed based on a force balance, and two different detachment mechanisms are identified. When the gas momentum is large, the bubble detaches from the injection orifice as the gas momentum overcomes the attaching effects of liquid drag and inertia. The surface tension force is much reduced because a large part of the bubble pinning edge at the orifice is lost as the bubble axis is tilted by the liquid flow. When the gas momentum is small, the force balance in the liquid flow direction is important, and the bubble detaches when the bubble axis inclination exceeds a certain angle.

  12. Microcomputed tomography analysis of mesiobuccal orifices and major apical foramen in first maxillary molars.

    PubMed

    Spagnuolo, Gianrico; Ametrano, Gianluca; D'Antò, Vincenzo; Formisano, Anna; Simeone, Michele; Riccitiello, Francesco; Amato, Massimo; Rengo, Sandro

    2012-01-01

    Aim of the study was to determined by microcomputed tomography (µCT) the horizontal distance between the main (MB1) and the second mesiobuccal canal (MB2) orifices, the vertical distance between the MB1 and MB2 orifices planes, and the distance between the anatomic apex and major apical foramen (AF). Furthermore, we characterized the entire internal and external anatomy of the MB, distalbuccal (DB) and palatal (P) maxillary first molars roots. Twenty-two intact extracted first maxillary molars were scanned by X-ray computed transaxial µCT and then 2D and 3D images were processed and analyzed. The results showed that 77.27% of the mesiobuccal (MB) roots presented a second MB canal, and 29.41% of the MB2 were independent from the MB1 canals. In 15 teeth, there were three root canal orifices on the chamber floor, and 10 of these teeth presented MB2 canals. The mean vertical distance between the MB1 and MB2 planes was 1.68 ± 0.83 mm. Seven teeth had four orifices. The mean horizontal interorificial distance between the MB1 and MB2 orifices was 1.21 ± 0.5 mm. Accessory canals were observed in 33.33% of the roots, loops in 6.06%, while isthmuses were found in 15 of the 22 MB roots. Of the total roots, 74.24% presented one foramen, while all of the roots showed a major apical foramen that was not coincident with the anatomic apex. Our µCT analysis provided interesting features on the horizontal and vertical distance between the MB1 and MB2 orifices and on the distance of AF and anatomic apex. These results have an important clinical value because might support the endodontist in the recruitment, negotiation and obturation of maxillary first molar canal system.

  13. Numerical study of liquid-hydrogen droplet generation from a vibrating orifice

    NASA Astrophysics Data System (ADS)

    Xu, J.; Celik, D.; Hussaini, M. Y.; Van Sciver, S. W.

    2005-08-01

    Atomic hydrogen propellant feed systems for far-future spacecraft may utilize solid-hydrogen particle carriers for atomic species that undergo recombination to create hot rocket exhaust. Such technology will require the development of particle generation techniques. One such technique could involve the production of hydrogen droplets from a vibrating orifice that would then freeze in cryogenic helium vapor. Among other quantities, the shape and size of the droplet are of particular interest. The present paper addresses this problem within the framework of the incompressible Navier-Stokes equations for multiphase flows, in order to unravel the basic mechanisms of droplet formation with a view to control them. Surface tension, one of the most important mechanisms to determine droplet shape, is modeled as the source term in the momentum equation. Droplet shape is tracked using a volume-of-fluid approach. A dynamic meshing technique is employed to accommodate the vibration of the generator orifice. Numerically predicted droplet shapes show satisfactory agreement with photographs of droplets generated in experiments. A parametric study is carried out to understand the influence of injection velocity, nozzle vibrational frequency, and amplitude on the droplet shape and size. The computational model provides a definitive qualitative picture of the evolution of droplet shape as a function of the operating parameters. It is observed that, primarily, the orifice vibrational frequency affects the shape, the vibrational amplitude affects the time until droplet detachment from the orifice, and the injection velocity affects the size. However, it does not mean that, for example, there is no secondary effect of amplitude on shape or size.

  14. A theoretical study of the acoustic impedance of orifices in the presence of a steady grazing flow

    NASA Technical Reports Server (NTRS)

    Rice, E. J.

    1976-01-01

    An analysis of the oscillatory fluid flow in the vicinity of a circular orifice with a steady grazing flow is presented. The study is similar to that of Hersh and Rogers but with the addition of the grazing flow. Starting from the momentum and continuity equations, a considerably simplified system of partial differential equations is developed with the assumption that the flow can be described by an oscillatory motion superimposed upon the known steady flow. The equations are seen to be linear in the region where the grazing flow effects are dominant, and a solution and the resulting orifice impedance are presented for this region. The nonlinearity appears to be unimportant for the usual conditions found in aircraft noise suppressors. Some preliminary conclusions of the study are that orifice resistance is directly proportional to grazing flow velocity (known previously from experimental data) and that the orifice inductive (mass reactance) end correction is not a function of grazing flow. This latter conclusion is contrary to the widely held notion that grazing flow removes the effect of the orifice inductive end correction. This conclusion also implies that the experimentally observed total inductance reduction with grazing flow might be in the flow within the orifice rather than in the end correction.

  15. Comparisons of wing pressure distribution from flight tests of flush and external orifices for Mach numbers from 0.50 to 0.97

    NASA Technical Reports Server (NTRS)

    Montoya, L. C.; Lux, D. P.

    1975-01-01

    Wing pressure distributions obtained in flight with flush orifice and external tubing orifice installations for Mach numbers from 0.50 to 0.97 are compared. The procedure used to install the external tubing orifice is discussed. The results indicate that external tubing orifice installations can give useful results.

  16. Load dependence of the effective regurgitant orifice area in a sheep model of aortic regurgitation.

    PubMed

    Reimold, S C; Byrne, J G; Caguioa, E S; Lee, C C; Laurence, R G; Peigh, P S; Cohn, L H; Lee, R T

    1991-10-01

    Treatment of patients with aortic regurgitation with vasodilators reduces regurgitant volume, ventricular dilation and left ventricular mass. Although these effects are presumably due to afterload reduction, it is also possible that the aortic regurgitant orifice area is not constant. To test the latter hypothesis, aortic regurgitation was created in 10 open chest sheep by partial resection of the noncoronary leaflet under direct visualization. Regurgitant flow was measured with an aortic supravalvular electromagnetic probe; aortic and left ventricular pressures were measured with catheter-tipped micromanometer pressure transducers. The effective regurgitant orifice area was calculated by a modification of the continuity equation in a manner similar to the Gorlin equation. The regurgitant orifice area was measured three times: after aortic regurgitation was created, after mean arterial pressure was increased by 15 to 25 mm Hg with intravenous dopamine and after mean arterial pressure was reduced by 15 to 25 mm Hg with intravenous sodium nitroprusside. Comparison of regurgitant volumes and areas obtained after creation of aortic regurgitation and at the conclusion of the experiment in the absence of dopamine or sodium nitroprusside demonstrated no significant change over time. Dopamine administration was associated with an 86 +/- 81% increase in regurgitant volume (p less than 0.01) and a 38 +/- 44% increase in regurgitant orifice area (p less than 0.01). Sodium nitroprusside administration resulted in a 51 +/- 14% decrease in regurgitant volume (p less than 0.001) and a 28 +/- 21% reduction in regurgitant orifice area (p = 0.007). In this model of acute aortic regurgitation, the effective regurgitant orifice area was altered by increasing or decreasing the aortic transvalvular pressure gradient.(ABSTRACT TRUNCATED AT 250 WORDS)

  17. Morphometric features of the right atrioventricular orifice in adult human hearts.

    PubMed

    Skwarek, M; Hreczecha, J; Dudziak, M; Jerzemowski, J; Szpinda, M; Grzybiak, M

    2008-02-01

    The normal data of the tricuspid valve complex is of great clinical importance in the light of progress in cardiosurgery and the development of novel operating techniques. A range of measurements for the right atrioventricular orifice in 96 human adult hearts was examined by means of anatomical dissection, inspection, examination, and statistical analyses. The length of the attachment of the anterior leaflet increased significantly between group I (aged 18-40 years) and group II (aged 41-64 years) in women only. In men there were no significant differences in this parameter between any of the three age groups. In addition, the attachment length of the posterior leaflet in women increased statistically in the second age group. In men, in contrast, the attachment length of the posterior leaflet did not increase significantly between the first and second age groups and became significantly larger only in oldest age group, consisting of men aged over 65. No statistically significant differences between the three age groups were found for the attachment length of the septal leaflet (p>0.05). In female hearts significant increases in the frontal and sagittal dimensions of the tricuspid valve orifice were observed between the second age group and the group aged over 65. In male hearts both the frontal and sagittal dimensions increased significantly with advanced age. The right atrioventricular orifice expressed as the ellipse area was statistically greater than the triangular area (p<0.01) in each age group. It should be noticed that both areas increased significantly during ageing. This study has demonstrated that the shape of the right atrioventricular orifice evolves during life, from a triangular shape to a more elliptical shape.

  18. Orifice-induced pressure error studies in Langley 7- by 10-foot high-speed tunnel

    NASA Technical Reports Server (NTRS)

    Plentovich, E. B.; Gloss, B. B.

    1986-01-01

    For some time it has been known that the presence of a static pressure measuring hole will disturb the local flow field in such a way that the sensed static pressure will be in error. The results of previous studies aimed at studying the error induced by the pressure orifice were for relatively low Reynolds number flows. Because of the advent of high Reynolds number transonic wind tunnels, a study was undertaken to assess the magnitude of this error at high Reynolds numbers than previously published and to study a possible method of eliminating this pressure error. This study was conducted in the Langley 7- by 10-Foot High-Speed Tunnel on a flat plate. The model was tested at Mach numbers from 0.40 to 0.72 and at Reynolds numbers from 7.7 x 1,000,000 to 11 x 1,000,000 per meter (2.3 x 1,000,000 to 3.4 x 1,000,000 per foot), respectively. The results indicated that as orifice size increased, the pressure error also increased but that a porous metal (sintered metal) plug inserted in an orifice could greatly reduce the pressure error induced by the orifice.

  19. Numerically based design of an orifice plate flowmetering system for human respiratory flow monitoring.

    PubMed

    Fortuna, A O; Gurd, J R

    1999-01-01

    During certain medical procedures, it is important to continuously measure the respiratory flow of a patient, as lack of proper ventilation can cause brain damage and ultimately death. The monitoring of the ventilatory condition of a patient is usually performed with the aid of flowmeters. However, water and other secretions present in the expired air can build up and ultimately block a traditional, restriction-based flowmeter; by using an orifice plate flowmeter, such blockages are minimized. This paper describes the design of an orifice plate flowmetering system including, especially, a description of the numerical and computational techniques adopted in order to simulate human respiratory and sinusoidal air flow across various possible designs for the orifice plate flowmeter device. Parallel computation and multigrid techniques were employed in order to reduce execution time. The simulated orifice plate was later built and tested under unsteady sinusoidal flows. Experimental tests show reasonable agreement with the numerical simulation, thereby reinforcing the general hypothesis that computational exploration of the design space is sufficiently accurate to allow designers of such systems to use this in preference to the more traditional, mechanical prototyping techniques.

  20. Microcomputed Tomography Analysis of Mesiobuccal Orifices and Major Apical Foramen in First Maxillary Molars

    PubMed Central

    Spagnuolo, Gianrico; Ametrano, Gianluca; D’Antò, Vincenzo; Formisano, Anna; Simeone, Michele; Riccitiello, Francesco; Amato, Massimo; Rengo, Sandro

    2012-01-01

    Objective: Aim of the study was to determined by microcomputed tomography (µCT) the horizontal distance between the main (MB1) and the second mesiobuccal canal (MB2) orifices, the vertical distance between the MB1 and MB2 orifices planes, and the distance between the anatomic apex and major apical foramen (AF). Furthermore, we characterized the entire internal and external anatomy of the MB, distalbuccal (DB) and palatal (P) maxillary first molars roots. Materials and Methods: Twenty-two intact extracted first maxillary molars were scanned by X-ray computed transaxial µCT and then 2D and 3D images were processed and analyzed. Results: The results showed that 77.27% of the mesiobuccal (MB) roots presented a second MB canal, and 29.41% of the MB2 were independent from the MB1 canals. In 15 teeth, there were three root canal orifices on the chamber floor, and 10 of these teeth presented MB2 canals. The mean vertical distance between the MB1 and MB2 planes was 1.68 ± 0.83 mm. Seven teeth had four orifices. The mean horizontal interorificial distance between the MB1 and MB2 orifices was 1.21 ± 0.5 mm. Accessory canals were observed in 33.33% of the roots, loops in 6.06%, while isthmuses were found in 15 of the 22 MB roots. Of the total roots, 74.24% presented one foramen, while all of the roots showed a major apical foramen that was not coincident with the anatomic apex. Conclusions: Our µCT analysis provided interesting features on the horizontal and vertical distance between the MB1 and MB2 orifices and on the distance of AF and anatomic apex. Clinical Relevance: These results have an important clinical value because might support the endodontist in the recruitment, negotiation and obturation of maxillary first molar canal system. PMID:22905069

  1. Balanced Orifice Plate

    NASA Technical Reports Server (NTRS)

    Kelley, Anthony R. (Inventor); Buskirk, Paul D. (Inventor)

    2006-01-01

    An orifice plate for use in a conduit through which fluid flows is defined by a central circular region having a radius R, and a ring-shaped region surrounding the central circular region. The ring-shaped region has holes formed therethrough with those holes centered at each radius R thereof satisfying a relationship A(sub R)=al(X(sub R)V(sub R)(sup b)) where A(sub R) is a sum of areas of those holes having centers at radius R, X(sub R) is a flow coefficient at radius R, V(sub R) is a velocity of the fluid that is to flow through the conduit at radius R, b is a constant selected to make at least one process variable (associated with the fluid that is to flow through the conduit) approximately equal at each radius R, and a is a constant that is equal to (X(sub R)A(sub R)V(sub R)(sup b)) at each radius R.

  2. Mixing of Multiple Jets With a Confined Subsonic Crossflow. Part 2; Opposed Rows of Orifices in Rectangular Ducts

    NASA Technical Reports Server (NTRS)

    Holdeman, James D.; Liscinsky, David S.; Bain, Daniel B.

    1997-01-01

    This paper summarizes experimental and computational results on the mixing of opposed rows of jets with a confined subsonic crossflow in rectangular ducts. The studies from which these results were excerpted investigated flow and geometric variations typical of the complex 3-D flowfield in the combustion chambers in gas turbine engines. The principal observation was that the momentum-flux ratio, J, and the orifice spacing, S/H, were the most significant flow and geometric variables. Jet penetration was critical, and penetration decreased as either momentum-flux ratio or orifice spacing decreased. It also appeared that jet penetration remained similar with variations in orifice size, shape, spacing, and momentum-flux ratio when the orifice spacing was inversely proportional to the square-root of the momentum-flux ratio. It was also seen that planar averages must be considered in context with the distributions. Note also that the mass-flow ratios and the offices investigated were often very large (jet-to-mainstream mass-flow ratio greater than 1 and the ratio of orifices-area-to-mainstream-cross-sectional-area up to 0.5 respectively), and the axial planes of interest were often just downstream of the orifice trailing edge. Three-dimensional flow was a key part of efficient mixing and was observed for all configurations.

  3. Prospective randomized clinical trial comparing laparoscopic cholecystectomy and hybrid natural orifice transluminal endoscopic surgery (NOTES) (NCT00835250).

    PubMed

    Noguera, José F; Cuadrado, Angel; Dolz, Carlos; Olea, José M; García, Juan C

    2012-12-01

    Natural orifice transluminal endoscopic surgery (NOTES) is a technique still in experimental development whose safety and effectiveness call for assessment through clinical trials. In this paper we present a three-arm, noninferiority, prospective randomized clinical trial of 1 year duration comparing the vaginal and transumbilical approaches for transluminal endoscopic surgery with the conventional laparoscopic approach for elective cholecystectomy. Sixty female patients between the ages of 18 and 65 years who were eligible for elective cholecystectomy were randomized in a ratio of 1:1:1 to receive hybrid transvaginal NOTES (TV group), hybrid transumbilical NOTES (TU group) or conventional laparoscopy (CL group). The main study variable was parietal complications (wound infection, bleeding, and eventration). The analysis was by intention to treat, and losses were not replaced. Cholecystectomy was successfully performed on 94% of the patients. One patient in the TU group was reconverted to CL owing to difficulty in maneuvering the endoscope. After a minimum follow-up period of 1 year, no differences were noted in the rate of parietal complications. Postoperative pain, length of hospital stay, and time off from work were similar in the three groups. No patient developed dyspareunia. Surgical time was longer among cases in which a flexible endoscope was used (CL, 47.04 min; TV, 64.85 min; TU, 59.80 min). NOTES approaches using the flexible endoscope are not inferior in safety or effectiveness to conventional laparoscopy. The transumbilical approach with flexible endoscope is as effective and safe as the transvaginal approach and is a promising, single-incision approach.

  4. Use of nose cap and fuselage pressure orifices for determination of air data for space shuttle orbiter below supersonic speeds

    NASA Technical Reports Server (NTRS)

    Larson, T. J.; Siemers, P. M., III

    1980-01-01

    Wind tunnel pressure measurements were acquired from orifices on a 0.1 scale forebody model of the space shuttle orbiter that were arranged in a preliminary configuration of the shuttle entry air data system (SEADS). Pressures from those and auxiliary orifices were evaluated for their ability to provide air data at subsonic and transonic speeds. The orifices were on the vehicle's nose cap and on the sides of the forebody forward of the cabin. The investigation covered a Mach number range of 0.25 to 1.40 and an angle of attack range from 4 deg. to 18 deg. An air data system consisting of nose cap and forebody fuselage orifices constitutes a complete and accurate air data system at subsonic and transonic speeds. For Mach numbers less than 0.80 orifices confined to the nose cap can be used as a complete and accurate air data system. Air data systems that use only flush pressure orifices can be used to determine basic air data on other aircraft at subsonic and transonic speeds.

  5. Effective regurgitant orifice area by the color Doppler flow convergence method for evaluating the severity of chronic aortic regurgitation. An animal study.

    PubMed

    Shiota, T; Jones, M; Yamada, I; Heinrich, R S; Ishii, M; Sinclair, B; Holcomb, S; Yoganathan, A P; Sahn, D J

    1996-02-01

    The aim of the present study was to evaluate dynamic changes in aortic regurgitant (AR) orifice area with the use of calibrated electromagnetic (EM) flowmeters and to validate a color Doppler flow convergence (FC) method for evaluating effective AR orifice area and regurgitant volume. In 6 sheep, 8 to 20 weeks after surgically induced AR, 22 hemodynamically different states were studied. Instantaneous regurgitant flow rates were obtained by aortic and pulmonary EM flowmeters balanced against each other. Instantaneous AR orifice areas were determined by dividing these actual AR flow rates by the corresponding continuous wave velocities (over 25 to 40 points during each diastole) matched for each steady state. Echo studies were performed to obtain maximal aliasing distances of the FC in a low range (0.20 to 0.32 m/s) and a high range (0.70 to 0.89 m/s) of aliasing velocities; the corresponding maximal AR flow rates were calculated using the hemispheric flow convergence assumption for the FC isovelocity surface. AR orifice areas were derived by dividing the maximal flow rates by the maximal continuous wave Doppler velocities. AR orifice sizes obtained with the use of EM flowmeters showed little change during diastole. Maximal and time-averaged AR orifice areas during diastole obtained by EM flowmeters ranged from 0.06 to 0.44 cm2 (mean, 0.24 +/- 0.11 cm2) and from 0.05 to 0.43 cm2 (mean, 0.21 +/- 0.06 cm2), respectively. Maximal AR orifice areas by FC using low aliasing velocities overestimated reference EM orifice areas; however, at high AV, FC predicted the reference areas more reliably (0.25 +/- 0.16 cm2, r = .82, difference = 0.04 +/- 0.07 cm2). The product of the maximal orifice area obtained by the FC method using high AV and the velocity time integral of the regurgitant orifice velocity showed good agreement with regurgitant volumes per beat (r = .81, difference = 0.9 +/- 7.9 mL/beat). This study, using strictly quantified AR volume, demonstrated little change

  6. Canine ovariectomy by hybrid or total natural orifice transluminal endoscopic surgery: technical feasibility study and pain assessment.

    PubMed

    Linhares, Marcella Teixeira; Feranti, João Pedro Scussel; Coradini, Gabriela Pesamosca; Martins, Letícia Reginato; Martins, Arthur Rodrigues; Sarturi, Vanessa Zanchi; Gavioli, Felipe Baldissarella; Machado Silva, Marco Augusto; de Ataíde, Michelli Westphal; Teixeira, Luciana Gonçalves; Brun, Maurício Veloso

    2018-06-13

    To compare technical feasibility, surgical time, surgical complications, and postoperative pain in ovariectomy (OVE) by hybrid and total natural orifice transluminal endoscopic surgery (NOTES). Prospective randomized clinical trial. Sixteen healthy and sexually intact bitches. Dogs were randomly assigned to the hybrid NOTES group (HNG; n = 8) and the total NOTES group (TNG; n = 8) to compare surgical time, pain scores and complications. Pain was assessed by using the visual analog scale (VAS) and the Melbourne pain scale (MPS). Surgical time did not differ between the experimental groups (HNG = 46.3 ± 18.5 minutes, TNG = 54.6 ± 31.1 minutes). Exteriorization of the ovaries through the vaginal wound was the major difficulty. Complications were minor in both groups and occurred intraoperatively only in the HNG, and in both groups post operatively. No dogs required rescue analgesia in the intraoperative or postoperative period. There were no differences in VAS or MPS scores between the groups for any surgical times except for the VAS assessment at 72 hours after extubation (HNG = 1.1 ± 0.3, TNG = 0.7 ± 0.4, P = .0221). Both NOTES techniques were comparable for canine OVE, with no requirement for additional analgesia in the postoperative periods. It was not possible to determine whether there was a clear advantage of one technique rather than the other. The minimally invasive techniques proposed for laparoscopic OVE are feasible for dogs with low pain scores and low rates of complications for both groups. © 2018 The American College of Veterinary Surgeons.

  7. On the propagation mechanism of a detonation wave in a round tube with orifice plates

    NASA Astrophysics Data System (ADS)

    Ciccarelli, G.; Cross, M.

    2016-09-01

    This study deals with the investigation of the detonation propagation mechanism in a circular tube with orifice plates. Experiments were performed with hydrogen air in a 10-cm-inner-diameter tube with the second half of the tube filled with equally spaced orifice plates. A self-sustained Chapman-Jouguet (CJ) detonation wave was initiated in the smooth first half of the tube and transmitted into the orifice-plate-laden second half of the tube. The details of the propagation were obtained using the soot-foil technique. Two types of foils were used between obstacles, a wall-foil placed on the tube wall, and a flat-foil (sooted on both sides) placed horizontally across the diameter of the tube. When placed after the first orifice plate, the flat foil shows symmetric detonation wave diffraction and failure, while the wall foil shows re-initiation via multiple local hot spots created when the decoupled shock wave interacts with the tube wall. At the end of the tube, where the detonation propagated at an average velocity much lower than the theoretical CJ value, the detonation propagation is much more asymmetric with only a few hot spots on the tube wall leading to local detonation initiation. Consecutive foils also show that the detonation structure changes after each obstacle interaction. For a mixture near the detonation propagation limit, detonation re-initiation occurs at a single wall hot spot producing a patch of small detonation cells. The local overdriven detonation wave is short lived, but is sufficient to keep the global explosion front propagating. Results associated with the effect of orifice plate blockage and spacing on the detonation propagation mechanism are also presented.

  8. Assessment of natural background radiation in one of the highest regions of Ecuador

    NASA Astrophysics Data System (ADS)

    Pérez, Mario; Chávez, Estefanía; Echeverría, Magdy; Córdova, Rafael; Recalde, Celso

    2018-05-01

    Natural background radiation was measured in the province of Chimborazo (Ecuador) with the following reference coordinates 1°40'00''S 78°39'00''W, where the furthest point to the center of the planet is located. Natural background radiation measurements were performed at 130 randomly selected sites using a Geiger Müller GCA-07W portable detector; these measurements were run at 6 m away from buildings or walls and 1 m above the ground. The global average natural background radiation established by UNSCEAR is 2.4 mSv y-1. In the study area measurements ranged from 0.57 mSv y-1 to 3.09 mSv y-1 with a mean value of 1.57 mSv y-1, the maximum value was recorded in the north of the study area at 5073 metres above sea level (m.a.s.l.), and the minimum value was recorded in the southwestern area at 297 m.a.s.l. An isodose map was plotted to represent the equivalent dose rate due to natural background radiation. An analysis of variance (ANOVA) between the data of the high and low regions of the study area showed a significant difference (p < α), in addition a linear correlation coefficient of 0.92 was obtained, supporting the hypothesis that in high altitude zones extraterrestrial radiation contributes significantly to natural background radiation.

  9. A three-dimensional insight into the complexity of flow convergence in mitral regurgitation: adjunctive benefit of anatomic regurgitant orifice area.

    PubMed

    Chandra, Sonal; Salgo, Ivan S; Sugeng, Lissa; Weinert, Lynn; Settlemier, Scott H; Mor-Avi, Victor; Lang, Roberto M

    2011-09-01

    Mitral effective regurgitant orifice area (EROA) using the flow convergence (FC) method is used to quantify the severity of mitral regurgitation (MR). However, it is challenging and prone to interobserver variability in complex valvular pathology. We hypothesized that real-time three-dimensional (3D) transesophageal echocardiography (RT3D TEE) derived anatomic regurgitant orifice area (AROA) can be a reasonable adjunct, irrespective of valvular geometry. Our goals were to 1) to determine the regurgitant orifice morphology and distance suitable for FC measurement using 3D computational flow dynamics and finite element analysis (FEA), and (2) to measure AROA from RT3D TEE and compare it with 2D FC derived EROA measurements. We studied 61 patients. EROA was calculated from 2D TEE images using the 2D-FC technique, and AROA was obtained from zoomed RT3DE TEE acquisitions using prototype software. 3D computational fluid dynamics by FEA were applied to 3D TEE images to determine the effects of mitral valve (MV) orifice geometry on FC pattern. 3D FEA analysis revealed that a central regurgitant orifice is suitable for FC measurements at an optimal distance from the orifice but complex MV orifice resulting in eccentric jets yielded nonaxisymmetric isovelocity contours close to the orifice where the assumptions underlying FC are problematic. EROA and AROA measurements correlated well (r = 0.81) with a nonsignificant bias. However, in patients with eccentric MR, the bias was larger than in central MR. Intermeasurement variability was higher for the 2D FC technique than for RT3DE-based measurements. With its superior reproducibility, 3D analysis of the AROA is a useful alternative to quantify MR when 2D FC measurements are challenging.

  10. Image Discrimination Models Predict Object Detection in Natural Backgrounds

    NASA Technical Reports Server (NTRS)

    Ahumada, Albert J., Jr.; Rohaly, A. M.; Watson, Andrew B.; Null, Cynthia H. (Technical Monitor)

    1994-01-01

    Object detection involves looking for one of a large set of object sub-images in a large set of background images. Image discrimination models only predict the probability that an observer will detect a difference between two images. In a recent study based on only six different images, we found that discrimination models can predict the relative detectability of objects in those images, suggesting that these simpler models may be useful in some object detection applications. Here we replicate this result using a new, larger set of images. Fifteen images of a vehicle in an other-wise natural setting were altered to remove the vehicle and mixed with the original image in a proportion chosen to make the target neither perfectly recognizable nor unrecognizable. The target was also rotated about a vertical axis through its center and mixed with the background. Sixteen observers rated these 30 target images and the 15 background-only images for the presence of a vehicle. The likelihoods of the observer responses were computed from a Thurstone scaling model with the assumption that the detectabilities are proportional to the predictions of an image discrimination model. Three image discrimination models were used: a cortex transform model, a single channel model with a contrast sensitivity function filter, and the Root-Mean-Square (RMS) difference of the digital target and background-only images. As in the previous study, the cortex transform model performed best; the RMS difference predictor was second best; and last, but still a reasonable predictor, was the single channel model. Image discrimination models can predict the relative detectabilities of objects in natural backgrounds.

  11. A sticky situation: management of spray polyurethane foam insulation in body orifices.

    PubMed

    Sowerby, Robert J; Sowerby, Leigh J; Vinden, Chris

    2011-11-01

    Spray polyurethane foam insulation is commonly used in the construction industry to fill gaps, seal, and insulate. We present three cases of intentional spray foam insertion in body orifices and discuss the management of such situations in the emergency department. This series includes a case of oral foam insertion used in a suicide attempt by suffocation and two cases of rectal insertion. All of these cases had potential long-term consequences; one was life-threatening. To our knowledge, this is the first published report on the medical management and removal of foam insulation from body orifices. In all three cases, the foam insulation material was successfully removed after allowing the material to harden.

  12. Vortex dynamics of very low aspect ratio rectangular orifice synthetic jets

    NASA Astrophysics Data System (ADS)

    Straccia, Joseph; Farnsworth, John; Experimental Aerodynamics Laboratory Team

    2017-11-01

    The vast majority of prior synthetic jet research has focused on actuators with either circular orifices or rectangular orifices with high aspect ratios (AR), i.e. AR >=25. The results reported in these studies have also been biased towards bulk and time averaged statistics of the jet, viewing them in a steady sense as a source of momentum addition. Recent work has revealed that the unsteady vortex dynamics in a synthetic jet can be very relevant to how the jet interacts with and influences the base flow. In this study the synthetic jet issued into a quiescent fluid by an actuator with low orifice aspect ratios (i.e. AR =2-18) was studied using Stereoscopic Particle Image Velocimetry (SPIV) with a special focus on the vortex dynamics. The progression of vortex ring axis switching is presented and a distinct difference between the axis switching dynamics of very low AR (AR <=6) and moderate AR (AR =6-24) vortex rings is discussed. The high resolution SPIV vector fields are also used to extract details of the vortex core structure which are compared to theoretical vortex models. Furthermore, the influence of axis switching on the circulation magnitude around the vortex ring is reported in addition to how circulation varies with time as the ring advects. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship Program under Grant No. (DGE 1144083).

  13. Impact of L/D on 90 Degree Sharp-Edge Orifice Flow with Manifold Passage Cross Flow (Preprint)

    DTIC Science & Technology

    2007-04-30

    that are observed by measurement as the flow transitions from non-cavitation to cavitation (turbulent flow), supercavitation , and finally separation in...include inception of cavitation, supercavitation , and separation. 15. SUBJECT TERMS 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF...cavitation to cavitation (turbulent flow), supercavitation , and finally separation in sharp-edge 90 degree orifices. This study includes orifice L/D from

  14. Effect of orifice length-diameter ratio on the coefficient of discharge of fuel-injection nozzles

    NASA Technical Reports Server (NTRS)

    Gelalles, A G; March, E T

    1931-01-01

    The variation of the coefficient of discharge with the length-diameter ratio of the orifice was determined for nozzles having single orifice 0.008 and 0.020 inch in diameter. Ratios from 0.5 to 10 were investigated at injection pressures from 500 to 5,000 pounds per square inch. The tests showed that, within the error of the observation, the coefficients were the same whether the nozzles were assembled at the end of a constant tube or in an automatic injection valve having a plain stem.

  15. Standards for discharge measurement with standardized nozzles and orifices

    NASA Technical Reports Server (NTRS)

    1940-01-01

    The following standards give the standardized forms for two throttling devices, standard nozzles and standard orifices, and enable them to be used in circular pipes without calibration. The definition of the standards are applicable in principle to the calibration and use of nonstandardized throttling devices, such as the venturi tube. The standards are valid, likewise, as a basis for discharge measurements in the German acceptance standards.

  16. The force required to fracture endodontically roots restored with various materials as intra-orifice barriers.

    PubMed

    Yasa, E; Arslan, H; Yasa, B; Akcay, M; Alsancak, M; Hatirli, H

    2017-10-01

    To evaluate the effect of various materials as intra-orifice barriers on the force required fracture roots. One hundred-thirty five mandibular premolars were decoronated and prepared up to size #40. The root canals were filled and randomly divided into two control and seven experimental groups (n = 15), as follows: Positive control group (the intra-orifice barrier cavity was not prepared), negative control group (the intra-orifice barrier cavity was prepared, but not filled), filling using glass ionomer cement, nano-hybrid composite resin, short fiber-reinforced composite, bulk-fill flowable composite, MTA Angelus, Micro Mega MTA or Biodentine. A fracture strength test was performed, and the data were analyzed using one-way ANOVA and Tukey's post hoc tests. Nano-hybrid composite, short fiber-reinforced composite, bulk-fill flow able composite, and glass ionomer cement increased the force required fracture the roots compared to the positive and negative control groups (P < 0.05). While MTA groups did not increase the force required fracture the roots compared to the control groups, Biodentine increased significantly. Within the limitations of the present study, the use of nano-hybrid composite, short fiber-reinforced composite, bulk-fill flowable composite, and glass ionomer cement as an intra-orifice barrier may be useful in reinforcing roots. MTA placement (MTA Angelus or Micro Mega MTA) did not significantly increase the fracture resistance of endodontically treated roots compared to the control groups, however Biodentine did.

  17. Effect of punch and orifice base sizes in different push-out test setups: stress distribution analysis.

    PubMed

    Zanatta, Rayssa Ferreira; Barreto, Bruno de Castro Ferreira; Xavier, Tathy Aparecida; Versluis, Antheunis; Soares, Carlos José

    2015-02-01

    This study evaluated the influence of punch and base orifice diameters on push-out test results by means of finite element analysis (FEA). FEA was performed using 3D models of the push-out test with 3 base orifice diameters (2.5, 3.0, and 3.5 mm) and 3 punch diameters (0.5, 1.0, and 1.5 mm) using MARC/MENTAT (MSC.Software). The image of a cervical slice from a root restored with a fiberglass post was used to construct the models. The mechanical properties of dentin, post, and resin cement were obtained from the literature. Bases and punches were constructed as rigid bodies. A 10-N force was applied by the punch in the center of the post in a nonlinear contact analysis. Modified von Mises stress, maximum principal stress, as well as shear and normal stress components were calculated. Both punch and base orifice sizes influenced the stress distribution of the push-out test. Bases with larger diameters and punches with smaller diameters caused higher stress in dentin and at the dentin/cement interface. FEA showed that the diameter of the orifice base had a more significant influence on the stress distribution than did the punch diameter. For this reason, both factors should be taken into account during push-out experimental tests.

  18. TWO-PHASE FLOW OF TWO HFC REFRIGERANT MIXTURES THROUGH SHORT-TUBE ORIFICES

    EPA Science Inventory

    The report gives results of an experimental investigation to develop an acceptable flow model for short tube orifice expansion devices used in heat pumps. The refrigerants investigated were two hydrofluorocarbon (HFC) mixtures considered hydrochlorofluorocarbon (HCFC)-22 replacem...

  19. Adjustable steam producing flexible orifice independent of fluid pressure

    NASA Technical Reports Server (NTRS)

    Morrison, Andrew D. (Inventor)

    1992-01-01

    A self-adjusting choke for a fluids nozzle includes a membrane constructed of a single piece of flexible or elastic material. This flexible material is shaped to fit into the outlet of a nozzle. The body of the membrane has at least two flow channels, from one face to the other, which directs two streams of water to cross at the opening of the nozzle or at some point beyond. The elasticity and thickness of the membrane is selected to match the range of expected pressures and fluid velocities. The choke may have more than two flow channels, as long as they are aligned adjacent to one another and directed towards each other at the exit face. In a three orifice embodiment, one is directed upward, one is directed downward, and the one in the middle is directed forward. In this embodiment all three fluid streams intersect at some point past the nozzle opening. Under increased pressure the membrane will deform causing the orifices to realign in a more forward direction, causing the streams to intersect at a smaller angle. This reduces the force with which the separate streams impact each other, still allowing the separate streams to unify into a single stable spiralling stream in spite of the increased pressure.

  20. Evolution and simplified terminology of natural orifice transluminal endoscopic surgery (NOTES), laparoendoscopic single-site surgery (LESS), and mini-laparoscopy (ML).

    PubMed

    Georgiou, A N; Rassweiler, J; Herrmann, T R; Stolzenburg, J U; Liatsikos, E N; Do, Eta Mu; Kallidonis, P; de la Teille, A; van Velthoven, R; Burchardt, M

    2012-10-01

    Natural orifice transluminal endoscopic surgery (NOTES) and laparoendoscopic single-site surgery (LESS) are the next steps in the evolution of laparoscopic surgery, promising reduced morbidity and improved cosmetic result. The inconsistent terminology initially used led to confusion. Understanding the technical evolution, the current status and a unified and simplified terminology are key issues for further acceptance of both approaches. To present LESS and NOTES in its historical context and to clarify the associated terminology. Extensive literature search took place using the PubMed. Several hundred publications in general surgery and urology regarding LESS are present including the expert opinion of members the European Society of Uro-technology (ESUT). The increasing interest on NOTES and LESS is reflected by a raising number of publications during the last 4 years. The initial confusion with the terminology of single-incision surgery represented a significant issue for further evolution of the technique. Thus, consortiums of experts searched a universally acceptable name for single-incision surgery. They determined that 'laparoendoscopic single-site surgery' (LESS) was both scientifically accurate and colloquially appropriate, the term being also ratified by the NOTES working group (Endourological Society) and the ESUT. For additional use of instruments, the terms hybrid NOTES and hybrid LESS should be used. Any single use of miniaturized instruments for laparoscopy should be called mini-laparoscopy. The evolution of LESS and most likely NOTES to a new standard of minimally invasive surgery could represent an evolutionary step even greater than the one performed by the establishment of laparoscopy over open surgery.

  1. Wind tunnel investigation of an all flush orifice air data system for a large subsonic aircraft. [conducted in a Langley 8 foot transonic pressure tunnel

    NASA Technical Reports Server (NTRS)

    Larson, T. J.; Flechner, S. G.; Siemers, P. M., III

    1980-01-01

    The results of a wind tunnel investigation on an all flush orifice air data system for use on a KC-135A aircraft are presented. The investigation was performed to determine the applicability of fixed all flush orifice air data systems that use only aircraft surfaces for orifices on the nose of the model (in a configuration similar to that of the shuttle entry air data system) provided the measurements required for the determination of stagnation pressure, angle of attack, and angle of sideslip. For the measurement of static pressure, additional flush orifices in positions on the sides of the fuselage corresponding to those in a standard pitot-static system were required. An acceptable but less accurate system, consisting of orifices only on the nose of the model, is defined and discussed.

  2. Transverse Injection into Subsonic Crossflow with Various Injector Orifice Geometries

    NASA Technical Reports Server (NTRS)

    Foster, Lancert E.; Zaman, Khairul B.

    2010-01-01

    Computational and experimental results are presented for a case study of single injectors employed in 90 deg transverse injection into a non-reacting subsonic flow. Different injector orifice shapes are used (including circular, square, diamond-shaped, and wide rectangular slot), all with constant cross-sectional area, to observe the effects of this variation on injector penetration and mixing. Whereas the circle, square, and diamond injector produce similar jet plumes, the wide rectangular slot produces a plume with less vertical penetration than the others. There is also some evidence that the diamond injector produces slightly faster penetration with less mixing of the injected fluid. In addition, a variety of rectangular injectors were analyzed, with varying length/width ratios. Both experimental and computational data show improved plume penetration with increased streamwise orifice length. 3-D Reynolds-Averaged Navier-Stokes (RANS) results are obtained for the various injector geometries using NCC (National Combustion Code) with the kappa-epsilon turbulence model in multi-species modes on an unstructured grid. Grid sensitivity results are also presented which indicate consistent qualitative trends in the injector performance comparisons with increasing grid refinement.

  3. The Effects of Air Preheat and Number of Orifices on Flow and Emissions in an RQL Mixing Section

    NASA Technical Reports Server (NTRS)

    Holdeman, James D.; Chang, Clarence T.

    2007-01-01

    This study was motivated by a goal to understand the mixing and emissions in the rich-burn/quick-mix/lean-burn (RQL) combustor scheme that has been proposed to minimize the formation of oxides of nitrogen (NOx) in gas turbine combustors. The study reported in this paper was a reacting jet-in-crossflow experiment at atmospheric pressure in a cylindrical duct. The jets were injected from the perimeter of the duct through round-hole orifices into a fuel-rich mainstream flow. The number of orifices investigated in this study gave over- to optimum to underpenetrating jets at a jet-to-mainstream momentum-flux ratio of 57. The size of individual orifices was decreased as their number increased to maintain a constant total area. The jet-to-mainstream mass-flow ratio was held constant at 2.5. The experiments focused on the effects of the number of orifices and inlet air preheat and were conducted in a facility that provided the capability for independent variation of jet and main inlet air preheat temperature. The number of orifices was found to have a significant effect on mixing and the distributions of species, but very little effect on overall NOx emissions, suggesting that an aerodynamically optimum mixer may not minimize NOx emissions. Air preheat was found to have very little effect on mixing and the distributions of major species, but preheat did increase NOx emissions significantly. Although the air jets injected in the quick-mix section of a RQL combustor may comprise over 70% of the total air flow, the overall NOx emission levels were found to be more sensitive to mainstream air preheat than to jet stream air preheat.

  4. Effect of nozzle orifice geometry on spray, combustion, and emission characteristics under diesel engine conditions.

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Som, S.; Longman, D. E; Ramirez, A. I.

    2011-03-01

    Diesel engine performance and emissions are strongly coupled with fuel atomization and spray processes, which in turn are strongly influenced by injector flow dynamics. Modern engines employ micro-orifices with different orifice designs. It is critical to characterize the effects of various designs on engine performance and emissions. In this study, a recently developed primary breakup model (KH-ACT), which accounts for the effects of cavitation and turbulence generated inside the injector nozzle is incorporated into a CFD software CONVERGE for comprehensive engine simulations. The effects of orifice geometry on inner nozzle flow, spray, and combustion processes are examined by coupling themore » injector flow and spray simulations. Results indicate that conicity and hydrogrinding reduce cavitation and turbulence inside the nozzle orifice, which slows down primary breakup, increasing spray penetration, and reducing dispersion. Consequently, with conical and hydroground nozzles, the vaporization rate and fuel air mixing are reduced, and ignition occurs further downstream. The flame lift-off lengths are the highest and lowest for the hydroground and conical nozzles, respectively. This can be related to the rate of fuel injection, which is higher for the hydroground nozzle, leading to richer mixtures and lower flame base speeds. A modified flame index is employed to resolve the flame structure, which indicates a dual combustion mode. For the conical nozzle, the relative role of rich premixed combustion is enhanced and that of diffusion combustion reduced compared to the other two nozzles. In contrast, for the hydroground nozzle, the role of rich premixed combustion is reduced and that of non-premixed combustion is enhanced. Consequently, the amount of soot produced is the highest for the conical nozzle, while the amount of NOx produced is the highest for the hydroground nozzle, indicating the classical tradeoff between them.« less

  5. Flow visualization of cavitating flows through a rectangular slot micro-orifice ingrained in a microchannel

    NASA Astrophysics Data System (ADS)

    Mishra, Chandan; Peles, Yoav

    2005-11-01

    Multifarious hydrodynamic cavitating flow patterns have been detected in the flow of de-ionized water through a 40.5μm wide and 100.8μm deep rectangular slot micro-orifice established inside a 202.6μm wide and 20 000μm long microchannel. This article presents and discusses the flow patterns observed at various stages of cavitation in the aforementioned micrometer-sized silicon device. Cavitation inception occurs with the appearance of inchoate bubbles that emerge from two thin vapor cavities that emanate from the boundaries of the constriction element. A reduction in the cavitation number beyond inception results in the development of twin coherent unsteady large vapor cavities, which appear just downstream of the micro-orifice and engulf the liquid jet. The shedding of both spherical and nonspherical vapor bubbles and their subsequent collapse into vapor plumes downstream of the orifice occurs intermittently. A further reduction in the exit pressure only aids in the elongation of the two coherent cavities and produces two stable vapor pockets. Additionally, interference fringes are clearly observed, showing that the vapor pocket has a curved interface with liquid. At low cavitation numbers, the flow undergoes a flip downstream and the two vapor pockets coalesce and form a single vapor pocket that is encircled by the liquid and extends until the exit of the microchannel. The cavitating flow patterns are unique and are markedly different from those reported for their macroworld counterparts. Evidence of pitting due to cavitation has been observed on the silicon just downstream of the micro-orifice. It is therefore apparent that cavitation will continue to influence/impact the design of high-speed MEMS hydraulic machines, and the pernicious effects of cavitation in terms of erosion, choking, and a reduction in performance will persist in microfluidic systems if apposite hydrodynamic conditions develop.

  6. Formation of Micro-Scale Gas Pockets From Underwater Wall Orifices

    NASA Astrophysics Data System (ADS)

    Pereira, Francisco A.; Gharib, Morteza

    2012-11-01

    Our experiments examine the formation of micro-scale gas pockets from orifices on walls with hydrophilic and hydrophobic wetting properties. Bubble injection is operated in a liquid at rest at constant flow rate and in a quasi-static regime, and the mechanism of bubble growth is investigated through high speed recordings. The growth dynamics is studied in terms of orifice size, surface wetting properties and buoyancy sign. The bubble formation is characterized by an explosive growth, with a pressure wave that causes the bubble to take highly transient shapes in its very initial stages, before stabilizing as a sphere and growing at a relatively slow rate. In case of positive buoyancy, the bubble elongates with the formation of a neck before detaching from the wall. When buoyancy acts towards the wall, the bubble attaches to the wall and expands laterally with a moving contact line. In presence of hydrophobic surfaces, the bubble attaches immediately to the wall irrespective of buoyancy direction and takes a hemispherical shape, expanding radially along the surface. A force balance is outlined to explain the different figures. The work was performed by FAP while on leave from CNR-INSEAN, and is supported by the Office of Naval Research (ONR).

  7. Experimental investigation on the effect of liquid injection by multiple orifices in the formation of droplets in a Venturi scrubber.

    PubMed

    Guerra, V G; Gonçalves, J A S; Coury, J R

    2009-01-15

    Venturi scrubbers are widely utilized in gas cleaning. The cleansing elements in these scrubbers are droplets formed from the atomization of a liquid into a dust-laden gas. In industrial scrubbers, this liquid is injected through several orifices so that the cloud of droplets can be evenly distributed throughout the duct. The interaction between droplets when injected through many orifices, where opposite clouds of atomized liquid can reach each other, is to be expected. This work presents experimental measurements of droplet size measured in situ and the evidence of cloud interaction within a Venturi scrubber operating with multi-orifice jet injection. The influence of gas velocity, liquid flow rate and droplet size variation in the axial position after the point of the injection of the liquid were also evaluated for the different injection configurations. The experimental results showed that an increase in the liquid flow rate generated greater interaction between jets. The number of orifices had a significant influence on droplet size. In general, the increase in the velocity of the liquid jet and in the gas velocity favored the atomization process by reducing the size of the droplets.

  8. An intercomparison of NEL and DHL water flow facilities using a twin orifice plate flowmeter assembly

    NASA Technical Reports Server (NTRS)

    Dejong, J.; Spencer, E. A.

    1983-01-01

    A 205 mm transfer standard orifice plate meter assembly, consisting of two orifice plates in series separated by a length of pipe containing a flow straightener, was calibrated in two water flow facilities. Results show that the agreement in the characteristics of such a differential pressure transfer standard package is within 0.17% over a 10:1 range from flow rates of approximately 8 to 80 l/sec. When the range over which the comparison was made was limited to that for which the calibration graphs gave straight lines, the agreement is 0.1% in 3 of the 4 calibrations (0.17% in the fourth).

  9. Dynamic change in mitral regurgitant orifice area: comparison of color Doppler echocardiographic and electromagnetic flowmeter-based methods in a chronic animal model.

    PubMed

    Shiota, T; Jones, M; Teien, D E; Yamada, I; Passafini, A; Ge, S; Sahn, D J

    1995-08-01

    The aim of the present study was to investigate dynamic changes in the mitral regurgitant orifice using electromagnetic flow probes and flowmeters and the color Doppler flow convergence method. Methods for determining mitral regurgitant orifice areas have been described using flow convergence imaging with a hemispheric isovelocity surface assumption. However, the shape of flow convergence isovelocity surfaces depends on many factors that change during regurgitation. In seven sheep with surgically created mitral regurgitation, 18 hemodynamic states were studied. The aliasing distances of flow convergence were measured at 10 sequential points using two ranges of aliasing velocities (0.20 to 0.32 and 0.56 to 0.72 m/s), and instantaneous flow rates were calculated using the hemispheric assumption. Instantaneous regurgitant areas were determined from the regurgitant flow rates obtained from both electromagnetic flowmeters and flow convergence divided by the corresponding continuous wave velocities. The regurgitant orifice sizes obtained using the electromagnetic flow method usually increased to maximal size in early to midsystole and then decreased in late systole. Patterns of dynamic changes in orifice area obtained by flow convergence were not the same as those delineated by the electromagnetic flow method. Time-averaged regurgitant orifice areas obtained by flow convergence using lower aliasing velocities overestimated the areas obtained by the electromagnetic flow method ([mean +/- SD] 0.27 +/- 0.14 vs. 0.12 +/- 0.06 cm2, p < 0.001), whereas flow convergence, using higher aliasing velocities, estimated the reference areas more reliably (0.15 +/- 0.06 cm2). The electromagnetic flow method studies uniformly demonstrated dynamic change in mitral regurgitant orifice area and suggested limitations of the flow convergence method.

  10. Preoperative ultrasound measurements predict the feasibility of gallbladder extraction during transgastric natural orifice translumenal endoscopic surgery cholecystectomy.

    PubMed

    Santos, Byron F; Auyang, Edward D; Hungness, Eric S; Desai, Kush R; Chan, Edward S; van Beek, Darren B; Wang, Edward C; Soper, Nathaniel J

    2011-04-01

    Extraction of a gallbladder through an endoscopic overtube during natural orifice translumenal endoscopic surgery (NOTES) transgastric cholecystectomy avoids potential injury to the esophagus. This study examined the rate of successful gallbladder specimen extraction through an overtube and hypothesized that preoperative ultrasound findings could predict successful specimen passage. Gallbladder specimens from patients undergoing laparoscopic cholecystectomy were measured, and an attempt was made to pull the specimens through a commercially available overtube with an inner diameter of 16.7-mm. A radiologist blinded to the outcomes reviewed the available preoperative ultrasound measurements from these patients. Ultrasound dimensions including gallbladder length, width, and depth; wall thickness; common bile duct diameter; and size of the largest gallstone (LGS) were recorded. Multiple logistic regression analysis was performed to determine whether ultrasound findings and patient characteristics (age, body mass index [BMI], and sex) could predict the ability of a specimen to pass through the overtube. Of 57 patients, 44 (77%) who had preoperative ultrasounds available for electronic review were included in the final analysis. Gallstones were present in 35 (79%) of these 44 patients. Intraoperative gallbladder perforation occurred in 18 (41%) of the 44 patients, and 16 (36%) of the 44 gallbladders could be extracted through the overtube. Measurement of LGS was possible for 23 patients, and indeterminate gallstone size (IGS) was determined for 12 patients. The rate for passage of perforated versus intact gallbladders was similar (40% vs. 23%; p = 0.054). The LGS (odds ratio [OR], 1.17; 95% confidence interval [CI], 1.02-1.33; p = 0.021) and IGS (OR, 22.97; 95% CI, 1.99-265.63; p = 0.025) predicted failed passage on multivariate logistic regression analysis. The passage rate was 80% for LGS smaller than 10 mm or no stones present, 18% for LGS 10 mm or larger, and 8% for

  11. Design of an Orifice and Weir Outlet for Poorly Drained Forested Watersheds

    Treesearch

    D.M. Amatya; R.W. Skaggs; J.H. Hughes

    1999-01-01

    Orifice-weir structures at ditch outlets are being used to reduce peak drainage rates and to store water during the growing season in poorly drained managed pine plantations. Earlier studies have shown their effectiveness on reducing drainage outflows while conserving water during the growing season. This study reports on criteria and preliminary guidelines for...

  12. High Amplitude Acoustic Behavior of a Slit-Orifice Backed by a Cavity

    NASA Technical Reports Server (NTRS)

    Ahuja, K. K.; Gaeta, R. J., Jr.; DAgostino, M.; Jones, Mike (Technical Monitor)

    2000-01-01

    The objective of the study reported here was to acquire detailed acoustic data and limited and flow visualization data for numerical validation a new model of sound absorption by a very narrow rectangular slit backed by a cavity. The sound absorption model is being developed by Dr. C. K. W. Tam of Florida State University. This report documents normal incidence impedance measurements of a singular rectangular slit orifice with no mean flow. All impedance measurements are made within a 1.12 inch (28.5 mm) diameter impedance tube using the two-microphone method for several frequencies in the range 1000-6000Hz and incident sound pressure levels in the range 130 - 150 dB. In the interest of leaving the analysis of the data to the developers of more advanced analytical and computational models of sound absorption by narrow slits, we have refrained from giving our own explanations of the observed results, although many of the observed results can be explained using the classical explanations of sound absorption by orifices.

  13. High Amplitude Acoustic Behavior of a Slit-Orifice Backed by a Cavity

    NASA Technical Reports Server (NTRS)

    Ahuja, K. K.; Gaeta, R. J., Jr.; DAgostino, M.

    2000-01-01

    The objective of this study was to acquire detailed acoustic data and limited flow visualization data for numerical validation of a new model of sound absorption by a very narrow rectangular slit backed by a cavity. The sound absorption model is that being developed by Dr. C. K. W. Tam of Florida State University. This report documents normal incidence impedance measurements of a singular rectangular slit orifice with no mean flow. All impedance measurements are made within a 1.12 inch (28.5 mm) diameter impedance tube using the two-microphone method for several frequencies in the range 1000 - 6000Hz and incident sound pressure levels in the range 130 - 150 dB. In the interest of leaving the analysis of the data to the developers of more advanced Analytical and computational models of sound absorption by narrow slits, we authors have refrained from giving our own explanations of the observed results, although many of the observed results can be explained using the classical understanding of sound absorption by orifices.

  14. Object detection in natural backgrounds predicted by discrimination performance and models

    NASA Technical Reports Server (NTRS)

    Rohaly, A. M.; Ahumada, A. J. Jr; Watson, A. B.

    1997-01-01

    Many models of visual performance predict image discriminability, the visibility of the difference between a pair of images. We compared the ability of three image discrimination models to predict the detectability of objects embedded in natural backgrounds. The three models were: a multiple channel Cortex transform model with within-channel masking; a single channel contrast sensitivity filter model; and a digital image difference metric. Each model used a Minkowski distance metric (generalized vector magnitude) to summate absolute differences between the background and object plus background images. For each model, this summation was implemented with three different exponents: 2, 4 and infinity. In addition, each combination of model and summation exponent was implemented with and without a simple contrast gain factor. The model outputs were compared to measures of object detectability obtained from 19 observers. Among the models without the contrast gain factor, the multiple channel model with a summation exponent of 4 performed best, predicting the pattern of observer d's with an RMS error of 2.3 dB. The contrast gain factor improved the predictions of all three models for all three exponents. With the factor, the best exponent was 4 for all three models, and their prediction errors were near 1 dB. These results demonstrate that image discrimination models can predict the relative detectability of objects in natural scenes.

  15. Simplified one-orifice venoplasty for middle hepatic vein reconstruction in adult living donor liver transplantation using right lobe grafts.

    PubMed

    Kim, Joo Dong; Choi, Dong Lak; Han, Young Seok

    2014-05-01

    Middle hepatic vein (MHV) reconstruction is often essential to avoid hepatic congestion and serious graft dysfunction in living donor liver transplantation (LDLT). The aim of this report was to introduce evolution of our MHV reconstruction technique and excellent outcomes of simplified one-orifice venoplasty. We compared clinical outcomes with two reconstruction techniques through retrospective review of 95 recipients who underwent LDLT using right lobe grafts at our institution from January 2008 to April 2012; group 1 received separate outflow reconstruction and group 2 received new one-orifice technique. The early patency rates of MHV in group 2 were higher than those in group 1; 98.4% vs. 88.2% on postoperative day 7 (p = 0.054) and 96.7% vs. 82.4% on postoperative day 14, respectively (p = 0.023). Right hepatic vein (RHV) stenosis developed in three cases in group 1, but no RHV stenosis developed because we adopted one-orifice technique (p = 0.043). The levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in group 2 were significantly lower than those in group 1 during the early post-transplant period. In conclusion, our simplified one-orifice venoplasty technique could secure venous outflow and improve graft function during right lobe LDLT. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  16. [Urethroplasty with transection of urethral orifice and preservation and lengthening of urethral plate: highly applicable to the treatment of hypospadias].

    PubMed

    Wang, Wen-Min; Qiu, Wei-Feng; Qian, Chong

    2010-07-01

    To explore the feasibility of urethroplasty with transection of the urethral orifice and preservation and lengthening of the urethral plate in the treatment of hypospadias. Forty-eight patients with hypospadias (18 of the coronal type, 21 the penile type, 8 the penoscrotal type and 1 the perineal type) underwent urethroplasty with transection of the urethral orifice and preservation and lengthening of the urethral plate. The surgical effects were observed by following up the patients for 3-27 months. One-stage surgical success was achieved in 44 of the cases, with satisfactory functional and cosmetic results but no complications. Two cases developed urinary fistula and another 2 urethral stricture, but all cured by the second surgery. Urethroplasty with transection of the urethral orifice and preservation and lengthening of the urethral plate is a simple, safe and effective surgical procedure for the treatment of hypospadias.

  17. Enucleation of facial sebaceous cyst by creating a minimal elliptical incision through a keratin-filled orifice.

    PubMed

    Chen, Wei-Liang

    2016-12-01

    A facial sebaceous cyst is a common benign epithelial tumor and surgical excision is frequently performed but may cause obvious scarring and may be esthetically troubling. This study evaluated the clinical outcomes of the patients with facial sebaceous cyst enucleated by creating minimal elliptical incisions through a keratin-filled orifice. Eleven patients with facial sebaceous cyst enucleated by creating minimal elliptical incisions through a keratin-filled orifice. We treated nine male and two female patients aged 25-52 years. The mean cyst size was 1.85 × 1.56 cm. All cysts were successfully enucleated. The mean wound length was 0.93 cm. The mean operative time was 15.2 min. The mean follow-up duration was 41.5 months. No recurrence was noted, and all patients were very satisfied with their esthetic outcomes. All cysts were successfully enucleated. The mean elliptical wound length was 0.93 cm (range, 0.8-1.1 cm). The mean operative time was 15.2 min. We found no evidence of wound infection, or nerve or vascular injury. Enucleation of facial sebaceous cyst via a minimal elliptical incision through the keratin-filled orifice was associated with high-level patient satisfaction, and the method is safe and useful for treating facial epidermoid cysts. © 2016 Wiley Periodicals, Inc.

  18. Calcification at orifices of aortic arch branches is a reliable and significant marker of stenosis at carotid bifurcation and intracranial arteries.

    PubMed

    Yamada, Shigeki; Hashimoto, Kenji; Ogata, Hideki; Watanabe, Yoshihiko; Oshima, Marie; Miyake, Hidenori

    2014-02-01

    Simple rating scale for calcification in the cervical arteries and the aortic arch on multi-detector computed tomography angiography (MDCTA) was evaluated its reliability and validity. Additionally, we investigated where is the most representative location for evaluating the calcification risk of carotid bifurcation stenosis and atherosclerotic infarction in the overall cervical arteries covering from the aortic arch to the carotid bifurcation. The aortic arch and cervical arteries among 518 patients (292 men, 226 women) were evaluated the extent of calcification using a 4-point grading scale for MDCTA. Reliability, validity and the concomitant risk with vascular stenosis and atherosclerotic infarction were assessed. Calcification was most frequently observed in the aortic arch itself, the orifices from the aortic arch, and the carotid bifurcation. Compared with the bilateral carotid bifurcations, the aortic arch itself had a stronger inter-observer agreement for the calcification score (Fleiss' kappa coefficients; 0.77), but weaker associations with stenosis and atherosclerotic infarction. Calcification at the orifices of the aortic arch branches had a stronger inter-observer agreement (0.74) and enough associations with carotid bifurcation stenosis and intracranial stenosis. In addition, the extensive calcification at the orifices from the aortic arch was significantly associated with atherosclerotic infarction, similar to the calcification at the bilateral carotid bifurcations. The orifices of the aortic arch branches were the novel representative location of the aortic arch and overall cervical arteries for evaluating the calcification extent. Thus, calcification at the aortic arch should be evaluated with focus on the orifices of 3 main branches. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  19. Computational Assessment of Naturally Occurring Neutron and Photon Background Radiation Produced by Extraterrestrial Sources

    DOE PAGES

    Miller, Thomas Martin; de Wet, Wouter C.; Patton, Bruce W.

    2015-10-28

    In this study, a computational assessment of the variation in terrestrial neutron and photon background from extraterrestrial sources is presented. The motivation of this assessment is to evaluate the practicality of developing a tool or database to estimate background in real time (or near–real time) during an experimental measurement or to even predict the background for future measurements. The extraterrestrial source focused on during this assessment is naturally occurring galactic cosmic rays (GCRs). The MCNP6 transport code was used to perform the computational assessment. However, the GCR source available in MCNP6 was not used. Rather, models developed and maintained bymore » NASA were used to generate the GCR sources. The largest variation in both neutron and photon background spectra was found to be caused by changes in elevation on Earth's surface, which can be as large as an order of magnitude. All other perturbations produced background variations on the order of a factor of 3 or less. The most interesting finding was that ~80% and 50% of terrestrial background neutrons and photons, respectively, are generated by interactions in Earth's surface and other naturally occurring and man-made objects near a detector of particles from extraterrestrial sources and their progeny created in Earth's atmosphere. In conclusion, this assessment shows that it will be difficult to estimate the terrestrial background from extraterrestrial sources without a good understanding of a detector's surroundings. Therefore, estimating or predicting background during a measurement environment like a mobile random search will be difficult.« less

  20. A unique case of "double-orifice aortic valve"-comprehensive assessment by 2-, 3-dimensional, and color Doppler echocardiography.

    PubMed

    Stirrup, James E; Cowburn, Peter J; Pousios, Dimitrios; Ohri, Sunil K; Shah, Benoy N

    2016-09-01

    Transesophageal echocardiography (TEE) is a powerful imaging tool for the comprehensive assessment of valvular structure and function. TEE may be of added benefit when anatomy is difficult to delineate accurately by transthoracic echocardiography. In this article, we present 2-, 3-dimensional, and color Doppler TEE images from a male patient with aortic stenosis. A highly unusual and complex pattern of valvular calcification created a functionally "double-orifice" valve. Such an abnormality may have implications for the accuracy of continuous-wave Doppler echocardiography, which assumes a single orifice valve in native aortic valves. © 2016, Wiley Periodicals, Inc.

  1. Three-dimensional color Doppler echocardiographic quantification of tricuspid regurgitation orifice area: comparison with conventional two-dimensional measures.

    PubMed

    Chen, Tien-En; Kwon, Susan H; Enriquez-Sarano, Maurice; Wong, Benjamin F; Mankad, Sunil V

    2013-10-01

    Three-dimensional (3D) color Doppler echocardiography (CDE) provides directly measured vena contracta area (VCA). However, a large comprehensive 3D color Doppler echocardiographic study with sufficiently severe tricuspid regurgitation (TR) to verify its value in determining TR severity in comparison with conventional quantitative and semiquantitative two-dimensional (2D) parameters has not been previously conducted. The aim of this study was to examine the utility and feasibility of directly measured VCA by 3D transthoracic CDE, its correlation with 2D echocardiographic measurements of TR, and its ability to determine severe TR. Ninety-two patients with mild or greater TR prospectively underwent 2D and 3D transthoracic echocardiography. Two-dimensional evaluation of TR severity included the ratio of jet area to right atrial area, vena contracta width, and quantification of effective regurgitant orifice area using the flow convergence method. Full-volume breath-hold 3D color data sets of TR were obtained using a real-time 3D echocardiography system. VCA was directly measured by 3D-guided direct planimetry of the color jet. Subgroup analysis included the presence of a pacemaker, eccentricity of the TR jet, ellipticity of the orifice shape, underlying TR mechanism, and baseline rhythm. Three-dimensional VCA correlated well with effective regurgitant orifice area (r = 0.62, P < .0001), moderately with vena contracta width (r = 0.42, P < .0001), and weakly with jet area/right atrial area ratio. Subgroup analysis comparing 3D VCA with 2D effective regurgitant orifice area demonstrated excellent correlation for organic TR (r = 0.86, P < .0001), regular rhythm (r = 0.78, P < .0001), and circular orifice (r = 0.72, P < .0001) but poor correlation in atrial fibrillation rhythm (r = 0.23, P = .0033). Receiver operating characteristic curve analysis for 3D VCA demonstrated good accuracy for severe TR determination. Three-dimensional VCA measurement is feasible and obtainable

  2. Method for generating small and ultra small apertures, slits, nozzles and orifices

    DOEpatents

    Khounsary, Ali M [Hinsdale, IL

    2012-05-22

    A method and device for one or more small apertures, slits, nozzles and orifices, preferably having a high aspect ratio. In one embodiment, one or more alternating layers of sacrificial layers and blocking layers are deposited onto a substrate. Each sacrificial layer is made of a material which preferably allows a radiation to substantially pass through. Each blocking layer is made of a material which substantially blocks the radiation.

  3. Use of natural diamonds to monitor 14C AMS instrument backgrounds

    NASA Astrophysics Data System (ADS)

    Taylor, R. E.; Southon, John

    2007-06-01

    To examine one component of the instrument-based background in the University of California Keck Carbon Cycle AMS spectrometer, we have obtained measurements on a set of natural diamonds pressed into sample holders. Natural diamond samples (N = 14) from different sources within rock formations with geological ages greatly in excess of 100 Ma yielded a range of currents (∼110-250 μA 12C- where filamentous graphite typically yields ∼150 μA 12C-) and apparent 14C ages (64.9 ± 0.4 ka BP [0.00031 ± 0.00002 fm] to 80.0 ± 1.1 ka BP [0.00005 ± 0.00001 fm]). Six fragments cut from a single diamond exhibited essentially identical 14C values - 69.3 ± 0.5 ka-70.6 ± 0.5 ka BP. The oldest 14C age equivalents were measured on natural diamonds which exhibited the highest current yields.

  4. Object Detection in Natural Backgrounds Predicted by Discrimination Performance and Models

    NASA Technical Reports Server (NTRS)

    Ahumada, A. J., Jr.; Watson, A. B.; Rohaly, A. M.; Null, Cynthia H. (Technical Monitor)

    1995-01-01

    In object detection, an observer looks for an object class member in a set of backgrounds. In discrimination, an observer tries to distinguish two images. Discrimination models predict the probability that an observer detects a difference between two images. We compare object detection and image discrimination with the same stimuli by: (1) making stimulus pairs of the same background with and without the target object and (2) either giving many consecutive trials with the same background (discrimination) or intermixing the stimuli (object detection). Six images of a vehicle in a natural setting were altered to remove the vehicle and mixed with the original image in various proportions. Detection observers rated the images for vehicle presence. Discrimination observers rated the images for any difference from the background image. Estimated detectabilities of the vehicles were found by maximizing the likelihood of a Thurstone category scaling model. The pattern of estimated detectabilities is similar for discrimination and object detection, and is accurately predicted by a Cortex Transform discrimination model. Predictions of a Contrast- Sensitivity- Function filter model and a Root-Mean-Square difference metric based on the digital image values are less accurate. The discrimination detectabilities averaged about twice those of object detection.

  5. Semi-empirical analysis of liquid fuel distribution downstream of a plain orifice injector under cross-stream air flow

    NASA Astrophysics Data System (ADS)

    Cao, M.-H.; Jiang, H.-K.; Chin, J.-S.

    1982-04-01

    An improved flat-fan spray model is used for the semi-empirical analysis of liquid fuel distribution downstream of a plain orifice injector under cross-stream air flow. The model assumes that, due to the aerodynamic force of the high-velocity cross air flow, the injected fuel immediately forms a flat-fan liquid sheet perpendicular to the cross flow. Once the droplets have been formed, the trajectories of individual droplets determine fuel distribution downstream. Comparison with test data shows that the proposed model accurately predicts liquid fuel distribution at any point downstream of a plain orifice injector under high-velocity, low-temperature uniform cross-stream air flow over a wide range of conditions.

  6. Real-Time 3-Dimensional Echocardiographic Assessment of Effective Regurgitant Orifice Area in Dogs With Myxomatous Mitral Valve Disease.

    PubMed

    Tidholm, A; Bodegård-Westling, A; Höglund, K; Häggström, J; Ljungvall, I

    2017-03-01

    Effective regurgitant orifice area (EROA), calculated from the vena contracta width (VCW) as the narrowest portion of the proximal regurgitant jet, might be used to estimate severity of mitral regurgitation. However, this simplified assumption only holds when the EROA is circular, which might not be true in dogs with myxomatous mitral valve disease (MMVD). Effective regurgitant orifice area in dogs with MMVD is noncircular, and using color Doppler real-time 3-dimensional (RT3D) echocardiography, measured EROA in the en face view will be significantly different from calculated EROA. Hundred and fifty-eight privately owned dogs with naturally occurring MMVD. Prospective observational study comparing en face view of EROA with calculated EROA using VCW in 4-chamber (4Ch) and 2-chamber (2Ch) view only or combined 4Ch and 2Ch views using RT3D echocardiography. The calculated EROA using the 2Ch view showed a systematic underestimation of 17% compared with the measured en face EROA corrected for body surface area. The calculated EROA using 4Ch and 4Ch + 2Ch views showed less agreement with the en face EROA, and the difference between methods increased with increasing EROA. The difference between calculated and measured EROA showed a systematic underestimation of the calculated EROA by 36% (4Ch) and 33% (4Ch + 2Ch), respectively, compared to measured en face EROA. When replacing measured EROA with calculated EROA using VCW measurements, the 2Ch view is preferred in dogs with MMVD. Copyright © 2017 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.

  7. Liquid hydrogen mass flow through a multiple orifice Joule-Thomson device

    NASA Astrophysics Data System (ADS)

    Papell, S. Stephen; Nyland, Ted W.; Saiyed, Naseem H.

    Liquid hydrogen mass flow rate, pressure drop, and temperature drop data were obtained for a number of multiple orifice Joule-Thomas devices known as visco jets. The present investigation continues a study to develop an equation for predicting two phase flow of cryogens through these devices. The test apparatus design allowed isenthalpic expansion of the cryogen through the visco jets. The data covered a range of inlet and outlet operating conditions. The mass flow rate range single phase or two phase was 0.015 to 0.98 lbm/hr. The manufacturer's equation was found to overpredict the single phase hydrogen data by 10 percent and the two phase data by as much as 27 percent. Two modifications of the equation resulted in a data correlation that predicts both the single and two phase flow across the visco jet. The first modification was of a theoretical nature, and the second strictly empirical. The former reduced the spread in the two phase data. It was a multiplication factor of 1 - X applied to the manufacturer's equation. The parameter X is the flow quality downstream of the visco jet based on isenthalpic expansion across the device. The latter modification was a 10 percent correction term that correlated 90 percent of the single and two phase data to within +/- 10 percent scatter band.

  8. Liquid hydrogen mass flow through a multiple orifice Joule-Thomson device

    NASA Technical Reports Server (NTRS)

    Papell, S. S.; Nyland, Ted W.; Saiyed, Naseem H.

    1992-01-01

    Liquid hydrogen mass flow rate, pressure drop, and temperature drop data were obtained for a number of multiple orifice Joule-Thomson devices known as visco jets. The present investigation continues a study to develop an equation for predicting two phase flow of cryogens through these devices. The test apparatus design allowed isenthalpic expansion of the cryogen through the visco jets. The data covered a range of inlet and outlet operating conditions. The mass flow rate range single phase or two phase was 0.015 to 0.98 lbm/hr. The manufacturer's equation was found to overpredict the single phase hydrogen data by 10 percent and the two phase data by as much as 27 percent. Two modifications of the equation resulted in a data correlation that predicts both the single and two phase flow across the visco jet. The first modification was of a theoretical nature, and the second strictly empirical. The former reduced the spread in the two phase data. It was a multiplication factor of 1-X applied to the manufacturer's equation. The parameter X is the flow quality downstream of the visco jet based on isenthalpic expansion across the device. The latter modification was a 10 percent correction term that correlated 90 percent of the single and two phase data to within +/- 10 percent scatter band.

  9. Liquid hydrogen mass flow through a multiple orifice Joule-Thomson device

    NASA Technical Reports Server (NTRS)

    Papell, S. Stephen; Nyland, Ted W.; Saiyed, Naseem H.

    1992-01-01

    Liquid hydrogen mass flow rate, pressure drop, and temperature drop data were obtained for a number of multiple orifice Joule-Thomas devices known as visco jets. The present investigation continues a study to develop an equation for predicting two phase flow of cryogens through these devices. The test apparatus design allowed isenthalpic expansion of the cryogen through the visco jets. The data covered a range of inlet and outlet operating conditions. The mass flow rate range single phase or two phase was 0.015 to 0.98 lbm/hr. The manufacturer's equation was found to overpredict the single phase hydrogen data by 10 percent and the two phase data by as much as 27 percent. Two modifications of the equation resulted in a data correlation that predicts both the single and two phase flow across the visco jet. The first modification was of a theoretical nature, and the second strictly empirical. The former reduced the spread in the two phase data. It was a multiplication factor of 1 - X applied to the manufacturer's equation. The parameter X is the flow quality downstream of the visco jet based on isenthalpic expansion across the device. The latter modification was a 10 percent correction term that correlated 90 percent of the single and two phase data to within +/- 10 percent scatter band.

  10. Liquid hydrogen mass flow through a multiple orifice Joule-Thomson device

    NASA Astrophysics Data System (ADS)

    Papell, S. S.; Nyland, Ted W.; Saiyed, Naseem H.

    1992-07-01

    Liquid hydrogen mass flow rate, pressure drop, and temperature drop data were obtained for a number of multiple orifice Joule-Thomson devices known as visco jets. The present investigation continues a study to develop an equation for predicting two phase flow of cryogens through these devices. The test apparatus design allowed isenthalpic expansion of the cryogen through the visco jets. The data covered a range of inlet and outlet operating conditions. The mass flow rate range single phase or two phase was 0.015 to 0.98 lbm/hr. The manufacturer's equation was found to overpredict the single phase hydrogen data by 10 percent and the two phase data by as much as 27 percent. Two modifications of the equation resulted in a data correlation that predicts both the single and two phase flow across the visco jet. The first modification was of a theoretical nature, and the second strictly empirical. The former reduced the spread in the two phase data. It was a multiplication factor of 1-X applied to the manufacturer's equation. The parameter X is the flow quality downstream of the visco jet based on isenthalpic expansion across the device. The latter modification was a 10 percent correction term that correlated 90 percent of the single and two phase data to within +/- 10 percent scatter band.

  11. Quantitative analysis of the side-branch orifice after bifurcation stenting using en-face processing of OCT images: a comparison between Xience V and Resolute Integrity stents.

    PubMed

    Minami, Yoshiyasu; Wang, Zhao; Aguirre, Aaron D; Lee, Stephen; Uemura, Shiro; Soeda, Tsunenari; Vergallo, Rocco; Raffel, Owen C; Barlis, Peter; Itoh, Tomonori; Lee, Hang; Fujimoto, James; Jang, Ik-Kyung

    2016-01-01

    Methods for intravascular assessment of the side-branch (SB) orifice after stenting are not readily available. The aim of this study was to assess the utility of an en-face projection processing for optical coherence tomography (OCT) images for SB evaluation. Measurements of the SB orifice obtained using en-face OCT images were validated using a phantom model. Linear regression modeling was applied to estimated area measurements made on the en-face images. The SB orifice was then analyzed in 88 patients with bifurcation lesions treated with either Xience V (everolimus-eluting stent) or Resolute Integrity [zotarolimus-eluting stent (ZES)]. The SB orifice area (A) and the area obstructed by struts (B) were calculated, and the %open area was evaluated as (A-B)/A*100. Linear regression modeling demonstrated that the observed departures of the intercept and slope were not significantly different from 0 (-0.12 ± 0.22, P=0.59) and 1 (1.01 ± 0.06, R(2)=0.88, P=0.87), respectively. In cases without SB dilatation, the %open area was significantly larger in the everolimus-eluting stent group (n=25) than in the ZES group [n=32; 89.2% (83.7-91.3) vs. 84.3% (78.9-87.8), P=0.04]. A significant difference in %open area between cases with and those without SB dilatation was demonstrated in the ZES group [91.4% (86.1-94.0) vs. 84.3% (78.9-87.8), P=0.04]. The accuracy of SB orifice measurement on an en-face OCT image was validated using a phantom model. This novel approach enables quantitative evaluation of the differences in SB orifice area free from struts among different stent types and different treatment strategies in vivo.

  12. Application of color Doppler flow mapping to calculate orifice area of St Jude mitral valve

    NASA Technical Reports Server (NTRS)

    Leung, D. Y.; Wong, J.; Rodriguez, L.; Pu, M.; Vandervoort, P. M.; Thomas, J. D.

    1998-01-01

    BACKGROUND: The effective orifice area (EOA) of a prosthetic valve is superior to transvalvular gradients as a measure of valve function, but measurement of mitral prosthesis EOA has not been reliable. METHODS AND RESULTS: In vitro flow across St Jude valves was calculated by hemispheric proximal isovelocity surface area (PISA) and segment-of-spheroid (SOS) methods. For steady and pulsatile conditions, PISA and SOS flows correlated with true flow, but SOS and not PISA underestimated flow. These principles were then used intraoperatively to calculate cardiac output and EOA of newly implanted St Jude mitral valves in 36 patients. Cardiac output by PISA agreed closely with thermodilution (r=0.91, Delta=-0.05+/-0.55 L/min), but SOS underestimated it (r=0.82, Delta=-1.33+/-0.73 L/min). Doppler EOAs correlated with Gorlin equation estimates (r=0.75 for PISA and r=0.68 for SOS, P<0.001) but were smaller than corresponding in vitro EOA estimates. CONCLUSIONS: Proximal flow convergence methods can calculate forward flow and estimate EOA of St Jude mitral valves, which may improve noninvasive assessment of prosthetic mitral valve obstruction.

  13. An Investigation of the Coefficient of Discharge of Liquids Through Small Round Orifices

    NASA Technical Reports Server (NTRS)

    Joachim, W F

    1926-01-01

    The work covered by this report was undertaken in connection with a general investigation of fuel injection engine principles as applied to engines for aircraft propulsion, the specific purpose being to obtain information on the coefficient of discharge of small round orifices suitable for use as fuel injection nozzles. Values for the coefficient were determined for the more important conditions of engine service such as discharge under pressures up to 8,000 pounds per square inch, at temperatures between 80 degrees and 180 degrees F. And into air compressed to pressures up to 1,000 pounds per square inch. The results show that the coefficient ranges between 0.62 and 0.88 for the different test conditions between 1,000 and 8,000 pounds per square inch hydraulic pressure. At lower pressures the coefficient increases materially. It is concluded that within the range of these tests and for hydraulic pressures above 1,000 pound per square inch the coefficient does not change materially with pressure or temperature; that it depends considerably upon the liquid, decreases with increase in orifice size, and increases in the case of discharge into compressed air until the compressed-air pressure equals approximately three-tenths of the hydraulic pressure, beyond which pressure ratio it remains practically constant.

  14. Method and apparatus for fine tuning an orifice pulse tube refrigerator

    DOEpatents

    Swift, Gregory W.; Wollan, John J.

    2003-12-23

    An orifice pulse tube refrigerator uses flow resistance, compliance, and inertance components connected to a pulse tube for establishing a phase relationship between oscillating pressure and oscillating velocity in the pulse tube. A temperature regulating system heats or cools a working gas in at least one of the flow resistance and inertance components. A temperature control system is connected to the temperature regulating system for controlling the temperature of the working gas in the at least one of the flow resistance and inertance components and maintains a control temperature that is indicative of a desired temporal phase relationship.

  15. Natural orifice transluminal endoscopic surgery gastrotomy closure with an over-the-endoscope clip: a randomized, controlled porcine study (with videos).

    PubMed

    von Renteln, Daniel; Schmidt, Arthur; Vassiliou, Melina C; Gieselmann, Maria; Caca, Karel

    2009-10-01

    Secure endoscopic closure of transgastric natural orifice transluminal endoscopic surgery (NOTES) access is of paramount importance. The over-the-scope clip (OTSC) system has previously been shown to be effective for NOTES gastrotomy closure. To compare OTSC gastrotomy closure with surgical closure. Randomized, controlled animal study. Animal facility laboratory. Thirty-six female domestic pigs. Gastrotomies were created by using a needle-knife and an 18-mm balloon. The animals were subsequently randomized to either open surgical repair with interrupted sutures or endoscopic repair with 12-mm OTSCs. In addition, pressurized leak tests were performed in ex vivo specimens of 18-mm scalpel incisions closed with suture (n = 14) and of intact stomachs (n = 10). The mean time for endoscopic closure was 9.8 minutes (range 3-22, SD 5.5). No complications occurred during either type of gastrotomy closure. At necropsy, examination of all OTSC and surgical closures demonstrated complete sealing of gastrotomy sites without evidence of injury to adjacent organs. Pressurized leak tests showed a mean burst pressure of 83 mm Hg (range 30-140, SD 27) for OTSC closures and 67 mm Hg (range 30-130, SD 27.7) for surgical sutures. Ex vivo hand-sewn sutures of 18-mm gastrotomies (n = 14) exhibited a mean burst pressure of 65 mm Hg (range 20-140, SD 31) and intact ex vivo stomachs (n = 10) had a mean burst pressure of 126 mm Hg (range 90-170, SD 28). The burst pressure of ex vivo intact stomachs was significantly higher compared with OTSC closures (P < .01), in vivo surgical closures (P < .01), and ex vivo hand-sewn closures (P < .01). There was a trend toward higher burst pressures in the OTSC closures compared with surgical closures (P = .063) and ex vivo hand-sewn closures (P = .094). In vivo surgical closures demonstrated similar burst pressures compared with ex vivo hand-sewn closures (P = .848). Nonsurvival setting. Endoscopic closure by using the OTSC system is comparable to

  16. Enumerating viruses by using fluorescence and the nature of the nonviral background fraction.

    PubMed

    Pollard, Peter C

    2012-09-01

    Bulk fluorescence measurements could be a faster and cheaper way of enumerating viruses than epifluorescence microscopy, flow cytometry, or transmission electron microscopy (TEM). However, since viruses are not imaged, the background fluorescence compromises the signal, and we know little about its nature. In this paper the size ranges of nucleotides that fluoresce in the presence of SYBR gold were determined for wastewater and a range of freshwater samples using a differential filtration method. Fluorescence excitation-emission matrices (FEEMs) showed that >70% of the SYBR fluorescence was in the <10-nm size fraction (background) and was not associated with intact viruses. This was confirmed using TEM. The use of FEEMs to develop a fluorescence-based method for counting viruses is an approach that is fundamentally different from the epifluorescence microscopy technique used for enumerating viruses. This high fluorescence background is currently overlooked, yet it has had a most pervasive influence on the development of a simple fluorescence-based method for quantifying viral abundance in water.

  17. Experimental study of cooling performance of pneumatic synthetic jet with singular slot rectangular orifice

    NASA Astrophysics Data System (ADS)

    Yu, Roger Ho Zhen; Ismail, Mohd Azmi bin; Ramdan, Muhammad Iftishah; Mustaffa, Nur Musfirah binti

    2017-03-01

    Synthetic Jet generates turbulence flow in cooling the microelectronic devices. In this paper, the experiment investigation of the cooling performance of pneumatic synthetic jet with single slot rectangular orifices at low frequency motion is presented. The velocity profile at the end of the orifice was measured and used as characteristic performance of synthetic jet in the present study. Frequencies of synthetic jet and the compressed air pressure supplied to the pneumatic cylinder (1bar to 5bar) were the parameters of the flow measurement. The air velocity of the synthetic jet was measured by using anemometer air flow meter. The maximum air velocity was 0.5 m/s and it occurred at frequency motion of 8 Hz. The optimum compressed air supplied pressure of the synthetic jet study was 4 bar. The cooling performance of synthetic jet at several driven frequencies from 0 Hz to 8 Hz and heat dissipation between 2.5W and 9W were also investigate in the present study. The results showed that the Nusselt number increased and thermal resistance decreased with both frequency and Reynolds number. The lowest thermal resistance was 5.25°C/W and the highest Nusselt number was 13.39 at heat dissipation of 9W and driven frequency of 8Hz.

  18. Natural orifice transgastric endoscopic wedge hepatic resection in an experimental model using an intuitively controlled master and slave transluminal endoscopic robot (MASTER).

    PubMed

    Phee, S J; Ho, K Y; Lomanto, D; Low, S C; Huynh, V A; Kencana, A P; Yang, K; Sun, Z L; Chung, S C Sydney

    2010-09-01

    The lack of triangulation of standard endoscopic devices limits the degree of freedom for surgical maneuvers during natural orifice transluminal endoscopic surgery (NOTES). This study explored the feasibility of adapting an intuitively controlled master and slave transluminal endoscopic robot (MASTER) the authors developed to facilitate wedge hepatic resection in NOTES. The MASTER consists of a master controller, a telesurgical workstation, and a slave manipulator that holds two end-effectors: a grasper, and a monopolar electrocautery hook. The master controller is attached to the wrist and fingers of the operator and connected to the manipulator by electrical and wire cables. Movements of the operator are detected and converted into control signals driving the slave manipulator via a tendon-sheath power transmission mechanism allowing nine degrees of freedom. Using this system, wedge hepatic resection was performed through the transgastric route on two female pigs under general anesthesia. Entry into the peritoneal cavity was via a 10-mm incision made on the anterior wall of the stomach by the electrocautery hook. Wedge hepatic resection was performed using the robotic grasper and hook. Hemostasis was achieved with the electrocautery hook. After the procedure, the resected liver tissue was retrieved through the mouth using the grasper. Using the MASTER, transgastric wedge hepatic resection was successfully performed on two pigs with no laparoscopic assistance. The entire procedure took 9.4 min (range, 8.5-10.2 min), with 7.1 min (range, 6-8.2 min) spent on excision of the liver tissue. The robotics-controlled device was able to grasp, retract, and excise the liver specimen successfully in the desired plane. This study demonstrated for the first time that the MASTER could effectively mitigate the technical constraints normally encountered in NOTES procedures. With it, the triangulation of surgical tools and the manipulation of tissue became easy, and wedge hepatic

  19. Pure natural orifice transluminal endoscopic surgery (NOTES) with ultrasonography-guided transgastric access and over-the-scope-clip closure: a porcine feasibility and survival study.

    PubMed

    Donatsky, Anders Meller; Andersen, Luise; Nielsen, Ole Lerberg; Holzknecht, Barbara Juliane; Vilmann, Peter; Meisner, Søren; Jørgensen, Lars Nannestad; Rosenberg, Jacob

    2012-07-01

    Most natural orifice transluminal endoscopic surgery (NOTES) procedures to date rely on the hybrid technique with simultaneous laparoscopic access to protect against access-related complications and to achieve adequate triangulation for dissection. This is done at the cost of the potential benefits of this new minimally invasive technique. This study aimed to evaluate the feasibility and safety of a transgastric (TG) pure-NOTES procedure in a diagnostic setting. A TG pure-NOTES procedure with endoscopic ultrasonograpy (EUS)-guided access and over-the-scope-clip (OTSC) closure was performed for 10 pigs in a survival and feasibility study. A full macroscopic necropsy with subsequent histologic evaluation was performed on postoperative day (POD) 14. The outcome parameters were uncomplicated follow-up assessment, survival, intraoperative complications, intraabdominal pathology, macroscopic full-thickness closure, and histology-proven full-thickness healing of the gastrotomy. An uncomplicated postoperative course was reported for 9 of the 10 pigs, and survival was reported for all 10 pigs. For all the pigs, EUS-guided access was performed successfully with a median duration of 25 min (range, 12-62 min) and without intraoperative complications or access-related lesions at necropsy. An OTSC closure was achieved with a median duration of 11 min (range, 3-28 min). The OTSC provided immediate closure, but according to the authors' definition of a full-thickness healing evaluated by histologic examination, this was not achieved in any of the cases. Although all the animals survived until POD 14, intraabdominal chronic abscesses were present in 3 of the 10 pigs at necropsy. The EUS-guided TG access proved to be feasible without access-related complications. Although OTSC provided an immediate closure, the histopathology raised concerns regarding the risk of perforation. Together with the high risk of intraabdominal infection, TG pure-NOTES is not yet ready for routine clinical

  20. Mixing of Multiple Jets with a Confined Subsonic Crossflow: Part III--The Effects of Air Preheat and Number of Orifices on Flow and Emissions in an RQL Mixing Section

    NASA Technical Reports Server (NTRS)

    Holdemann, James D.; Chang, Clarence T.

    2008-01-01

    This study was motivated by a goal to understand the mixing and emissions in the Rich-burn/Quick-mix/Lean-burn (RQL) combustor scheme that has been proposed to minimize the formation of oxides of nitrogen (NOx) in gas turbine combustors. The study reported herein was a reacting jet-in-crossflow experiment at atmospheric pressure. The jets were injected from the perimeter of a cylindrical duct through round-hole orifices into a fuel-rich mainstream flow. The number of orifices investigated in this study gave over- to optimum to underpenetrating jets at a jet-to-mainstream momentum-flux ratio of J = 57. The size of individual orifices was decreased as the number of orifices increased to maintain a constant total area; the jet-to-mainstream mass-flow ratio was constant at MR = 2.5. The experiments focused on the effects of the number of orifices and inlet air preheat and were conducted in a facility that provided the capability for independent variation of jet and main inlet air preheat temperature. The number of orifices was found to have a significant effect on mixing and the distributions of species, but very little effect on overall NOx emissions, suggesting that an aerodynamically optimum mixer might not minimize NOx emissions. Air preheat was found to have very little effect on mixing and the distributions of major species, but preheating both main and jet air did increase NOx emissions significantly. Although the air jets injected in the quick-mix section of an RQL combustor may comprise over 70 percent of the total air flow, the overall NOx emission levels were found to be more sensitive to main stream air preheat than to jet stream air preheat.

  1. The Influence of Swirl Brakes and a Tip Discharge Orifice on the Rotordynamic Forces Generated by Discharge-to-Suction Leakage Flows in Shrouded Centrifugal Pumps

    NASA Technical Reports Server (NTRS)

    Sivo, Joseph M.; Acosta, A. J.; Brennen, C. E.; Caughey, T. K.

    1993-01-01

    Recent experiments conducted in the Rotor Force Test Facility at the California Institute of Technology have examined the effects of a tip leakage restriction and swirl brakes on the rotordynamic forces due to leakage flows on an impeller undergoing a prescribed circular whirl. The experiments simulate the leakage flow conditions and geometry of the Alternate Turbopump Design (ATD) of the Space Shuttle High Pressure Oxygen Turbopump and are critical to evaluating the pump's rotordynamic instability problems. Previous experimental and analytical results have shown that discharge-to-suction leakage flows in the annulus of a shrouded centrifugal pump contribute substantially to the fluid induced rotordynamic forces. Also, previous experiments have shown that leakage inlet (pump discharge) swirl can increase the cross-coupled stiffness coefficient and hence increase the range of positive whirl for which the tangential force is destabilizing. In recent experimental work, the present authors demonstrated that when the swirl velocity within the leakage path is reduced by the introduction of ribs or swirl brakes, then a substantial decrease in both the destabilizing normal and tangential forces could be achieved. Motivation for the present research is that previous experiments have shown that restrictions such as wear rings or orifices at pump inlets affect the leakage forces. Recent pump designs such as the Space Shuttle Alternate Turbopump Design (ATD) utilize tip orifices at discharge for the purpose of establishing axial thrust balance. The ATD has experienced rotordynamic instability problems and one may surmise that these tip discharge orifices may also have an important effect on the normal and tangential forces in the plane of impeller rotation. The present study determines if such tip leakage restrictions contribute to undesirable rotordynamic forces. Additional motivation for the present study is that the widening of the leakage path annular clearance and the

  2. Transvaginal Laparoscopic Appendectomy Simultaneously with Vaginal Hysterectomy: Initial Experience of 10 Cases

    PubMed Central

    Tian, Yu; Wu, Shuo-Dong; Chen, Ying-Han; Wang, Dan-Bo

    2014-01-01

    Background Natural orifice transluminal endoscopic surgery (NOTES) involves the introduction of instruments through a natural orifice into the peritoneal cavity to perform surgical interventions. The vagina is the most widely used approach to NOTES. We report the utilization of the vaginal opening at the time of vaginal hysterectomy as a natural orifice for laparoscopic appendectomy. Material/Methods We reviewed cases of 10 patients with chronic appendicitis who underwent transvaginal laparoscopic appendectomy simultaneously with vaginal hysterectomy. A laparoscopic approach was established after removal of the uterus, and the appendix was removed transvaginally. Among the 10 cases, 5 were conducted under gasless laparoscopy by using a simple abdominal wall-lifting instrument. Results All procedures were performed successfully without intraoperative or major postoperative complications. The appendectomy portion of the procedure took approximately 21 minutes to 34 minutes. All patients were discharged less than 4 days after surgery, without external scars. Conclusions Transvaginal appendectomy with rigid laparoscopic instruments following vaginal hysterectomy appears to be a feasible and safe modification of established techniques, with acceptable outcomes. PMID:25300522

  3. The acoustic impedance of a circular orifice in grazing mean flow: comparison with theory.

    PubMed

    Peat, Keith S; Ih, Jeong-Guon; Lee, Seong-Hyun

    2003-12-01

    It is well known that the presence of a grazing mean flow affects the acoustic impedance of an aperture, but the detailed nature and understanding of the influence is still unknown. In this paper, results from a recent theoretical analysis of the problem are compared with a new set of experimental results. The purpose is twofold. First, the experimental results are used to validate the theory. It is found that the theory predicts the resistance quite well, but not the reactance. Second, the theory is used to try and give some physical understanding to the experimental results. In particular, some scaling laws are confirmed, and it is also shown that measured negative resistance values are to be expected. They are not erroneous, as previously thought. Former sets of experimental data for this problem are notable for the amount of variation that they display. Thus, both the theory and the new experimental results are also compared with those earlier detailed results that most closely conform to the conditions assumed here, namely fully developed turbulent pipe flow of low Mach number past circular orifices. The main field of application is in flow ducts, in particular, flow through perforated tubes in exhaust mufflers.

  4. Aortic valve orifice equation independent of valvular flow intervals: application to aortic valve area computation in aortic stenosis and comparison with the Gorlin formula.

    PubMed

    Seitz, W; Oppenheimer, L; McIlroy, M; Nelson, D; Operschall, J

    1986-12-01

    An orifice equation is derived relating the effective aortic valve area, A, the average aortic valve pressure gradient, dP, the stroke volume, SV, and the heart frequency, FH, through considerations of momentum conservation across the aortic valve. This leads to a formula consistent with Newton's second law of motion. The form of the new equation is A = (7.5 X 10(-5)) SV FH2/Pd, where A, VS, FH and Pd are expressed in cm2, ml, s-1 and mmHg, respectively. Aortic valve areas computed with the new orifice equation are found to correlate with those computed by the Gorlin formula in conditions of resting haemodynamic states at a level of r = 0.86, SE = 0.25 cm2, N = 120. The results suggest that the new formula may be considered as an independent orifice equation having a similar domain of validity as the Gorlin formula. The new equation offers the possibility of deriving additional useful haemodynamic relationships through combination with established cardiological formulas and applying it in a noninvasive Doppler ultrasonic or echocardiographic context.

  5. Quantification of instantaneous flow rate and dynamically changing effective orifice area using a geometry independent three-dimensional digital color Doppler method: An in vitro study mimicking mitral regurgitation.

    PubMed

    Li, Xiaokui; Wanitkun, Suthep; Li, Xiang-Ning; Hashimoto, Ikuo; Mori, Yoshiki; Rusk, Rosemary A; Hicks, Shannon E; Sahn, David J

    2002-10-01

    Our study was intended to test the accuracy of a 3-dimensional (3D) digital color Doppler flow convergence (FC) method for assessing the effective orifice area (EOA) in a new dynamic orifice model mimicking a variety of mitral regurgitation. FC surface area methods for detecting EOA have been reported to be useful for quantifying the severity of valvular regurgitation. With our new 3D digital direct FC method, all raw velocity data are available and variable Nyquist limits can be selected for computation of direct FC surface area for computing instantaneous flow rate and temporal change of EOA. A 7.0-MHz multiplane transesophageal probe from an ultrasound system (ATL HDI 5000) was linked and controlled by a computer workstation to provide 3D images. Three differently shaped latex orifices (zigzag, arc, and straight slit, each with cutting-edge length of 1 cm) were used to mimic the dynamic orifice of mitral regurgitation. 3D FC surface computation was performed on parallel slices through the 3D data set at aliasing velocities (14-48 cm/s) selected to maximize the regularity and minimize lateral dropout of the visualized 3D FC at 5 points per cardiac cycle. Using continuous wave velocity for each, 3D-calculated EOA was compared with EOA determined by using continuous wave Doppler and the flow rate from a reference ultrasonic flow meter. Simultaneous digital video images were also recorded to define the actual orifice size for 9 stroke volumes (15-55 mL/beat with maximum flow rates 45-182 mL/s). Over the 9 pulsatile flow states and 3 orifices, 3D FC EOAs (0.05-0.63 cm(2)) from different phases of the cardiac cycle in each pump setting correlated well with reference EOA (r = 0.89-0.92, SEE = 0.027-0.055cm(2)) and they also correlated well with digital video images of the actual orifice peak (r = 0.97-0.98, SEE = 0.016-0.019 cm(2)), although they were consistently smaller, as expected by the contraction coefficient. The digital 3D FC method can accurately predict flow

  6. Disinfection of Escherichia coli bacteria using hybrid method of ozonation and hydrodynamic cavitation with orifice plate

    NASA Astrophysics Data System (ADS)

    Karamah, Eva F.; Ghaudenson, Rioneli; Amalia, Fitri; Bismo, Setijo

    2017-11-01

    This research aims to evaluate the performance of hybrid method of ozonation and hydrodynamic cavitation with orifice plate on E.coli bacteria disinfection. In this research, ozone dose, circulation flowrate, and disinfection method were varied. Ozone was produced by commercial ozonator with ozone dose of 64.83 mg/hour, 108.18 mg/hour, and 135.04 mg/hour. Meanwhile, hydrodynamic cavitation was generated by an orifice plate. The disinfection method compared in this research were: hydrodynamic cavitation, ozonation, and the combination of both. The best result on each method was achieved on the 60th minutes and with a circulation flowrate of 7 L/min. The hybrid method attained final concentration of 0 CFU/mL from the initial concentration of 2.10 × 105 CFU/mL. The ozonation method attained final concentration of 0 CFU/mL from the initial concentration of 1.32 × 105 CFU/mL. Cavitation method gives the least disinfection with final concentration of 5.20 × 104 CFU/mL from the initial concentration of 2.17 × 105 CFU/mL. In conclusion, hybrid method gives a faster and better disinfection of E.coli than each method on its own.

  7. A new experimental method for the determination of the effective orifice area based on the acoustical source term

    NASA Astrophysics Data System (ADS)

    Kadem, L.; Knapp, Y.; Pibarot, P.; Bertrand, E.; Garcia, D.; Durand, L. G.; Rieu, R.

    2005-12-01

    The effective orifice area (EOA) is the most commonly used parameter to assess the severity of aortic valve stenosis as well as the performance of valve substitutes. Particle image velocimetry (PIV) may be used for in vitro estimation of valve EOA. In the present study, we propose a new and simple method based on Howe’s developments of Lighthill’s aero-acoustic theory. This method is based on an acoustical source term (AST) to estimate the EOA from the transvalvular flow velocity measurements obtained by PIV. The EOAs measured by the AST method downstream of three sharp-edged orifices were in excellent agreement with the EOAs predicted from the potential flow theory used as the reference method in this study. Moreover, the AST method was more accurate than other conventional PIV methods based on streamlines, inflexion point or vorticity to predict the theoretical EOAs. The superiority of the AST method is likely due to the nonlinear form of the AST. There was also an excellent agreement between the EOAs measured by the AST method downstream of the three sharp-edged orifices as well as downstream of a bioprosthetic valve with those obtained by the conventional clinical method based on Doppler-echocardiographic measurements of transvalvular velocity. The results of this study suggest that this new simple PIV method provides an accurate estimation of the aortic valve flow EOA. This new method may thus be used as a reference method to estimate the EOA in experimental investigation of the performance of valve substitutes and to validate Doppler-echocardiographic measurements under various physiologic and pathologic flow conditions.

  8. A small, single stage orifice pulse tube cryocooler demonstration

    NASA Technical Reports Server (NTRS)

    Hendricks, John B.

    1990-01-01

    This final report summarizes and presents the analytical and experimental progress in the present effort. The principal objective of this effort was the demonstration of a 0.25 Watt, 80 Kelvin orifice pulse tube refrigerator. The experimental apparatus is described. The design of a partially optimized pulse tube refrigerator is included. The refrigerator demonstrates an ultimate temperature of 77 K, has a projected cooling power of 0.18 Watts at 80 K, and has a measured cooling power of 1 Watt at 97 K, with an electrical efficiency of 250 Watts/Watt, much better than previous pulse tube refrigerators. A model of the pulse tube refrigerator that provides estimates of pressure ratio and mass flow within the pulse tube refrigerator, based on component physical characteristics is included. A model of a pulse tube operation based on generalized analysis which is adequate to support local optimization of existing designs is included. A model of regenerator performance based on an analogy to counterflow heat exchangers is included.

  9. Influence of Geometry and Flow Variation on Jet Mixing and NO Formation in a Model Staged Combustor Mixer with Eight Orifices

    NASA Technical Reports Server (NTRS)

    Samuelsen, G. S.; Sowa, W. A.; Hatch, M. S.

    1996-01-01

    A series of non-reacting parametric experiments was conducted to investigate the effect of geometric and flow variations on mixing of cold jets in an axis-symmetric, heated cross flow. The confined, cylindrical geometries tested represent the quick mix region of a Rich-Burn/Quick-Mix/Lean-Burn (RQL) combustor. The experiments show that orifice geometry and jet to mainstream momentum-flux ratio significantly impact the mixing characteristic of jets in a cylindrical cross stream. A computational code was used to extrapolate the results of the non-reacting experiments to reacting conditions in order to examine the nitric oxide (NO) formation potential of the configurations examined. The results show that the rate of NO formation is highest immediately downstream of the injection plane. For a given momentum-flux ratio, the orifice geometry that mixes effectively in both the immediate vicinity of the injection plane, and in the wall regions at downstream locations, has the potential to produce the lowest NO emissions. The results suggest that further study may not necessarily lead to a universal guideline for designing a low NO mixer. Instead, an assessment of each application may be required to determine the optimum combination of momentum-flux ratio and orifice geometry to minimize NO formation. Experiments at reacting conditions are needed to verify the present results.

  10. Air-surface exchange measurements of gaseous elemental mercury over naturally enriched and background terrestrial landscapes in Australia

    NASA Astrophysics Data System (ADS)

    Edwards, G. C.; Howard, D. A.

    2012-10-01

    This paper presents the first gaseous elemental mercury (GEM) air-surface exchange measurements obtained over naturally enriched and background (< 0.1 μg g-1 Hg) terrestrial landscapes in Australia. Two pilot field studies were carried out during the Australian autumn and winter periods at a copper-gold-cobalt-arsenic-mercury mineral field near Pulganbar, NSW. GEM fluxes using a dynamic flux chamber approach were measured, along with controlling environmental parameters over three naturally enriched and three background substrates. The enriched sites results showed net emission to the atmosphere and a strong correlation between flux and substrate Hg concentration, with average fluxes ranging from 14 ± 1 ng m-2 h-1 to 113 ± 6 ng m-2 h-1. Measurements at background sites showed both emission and deposition. The average Hg flux from all background sites showed an overall net emission of 0.36 ± 0.06 ng m-2 h-1. Fluxes show strong relationships with temperature, radiation, and substrate parameters. A compensation point of 2.48, representative of bare soils was determined. Comparison of the Australian data to North American data confirmed the need for Australian specific mercury air-surface exchange data representative of Australia's unique climatic conditions, vegetation types, land use patterns, and soils.

  11. Performance of a High-Speed Compression-Ignition Engine Using Multiple Orifice Fuel Injection Nozzles

    NASA Technical Reports Server (NTRS)

    Spanogle, J A; Foster, H H

    1930-01-01

    This report presents test results obtained at the Langley Memorial Aeronautical Laboratory of the National Advisory Committee for Aeronautics during an investigation to determine the relative performance of a single-cylinder, high-speed, compression-ignition engine when using fuel injection valve nozzles with different numbers, sizes, and directions of round orifices. A spring-loaded, automatic injection valve was used, centrally located at the top of a vertical disk-type combustion chamber formed between horizontally opposed inlet and exhaust valves of a 5 inch by 7 inch engine.

  12. Phenolics occurrence in surface water of the Dniester river basin (West Ukraine): natural background and industrial pollution

    NASA Astrophysics Data System (ADS)

    Sprynskyy, M.; Lebedynets, M.; Namieśnik, J.; Buszewski, B.

    2007-09-01

    Phenolics’ occurrence in surface water of the Dniester river basin (West Ukraine) with the definition of the natural background is studied. The main attention is given to the Upper Dniester basin and its tributary Stryj as the parts of the Sub-Carpathian oil- and gas province with the numerous objects of oil industry. The total amount of phenolics in water is studied. Phenolics’ concentrations from the first micrograms to the first milligrams per litre have been found in the surface water of the region. The natural background is defined as 0.012 mg l-1 for the areas out of the industrial influence. The anthropogenic part of phenolics is caused mainly by oil industry. The oil-producing objects provide the main phenolics’ releases in the region, due to the low protection level of mechanical facilities as well as to breach of technological norms on the oil-extracting objects. A man-made pollution of the basin water has a regional character and the natural self-purification processes seem to be insufficient for its neutralisation on the plains in particular.

  13. Multiple-orifice liquid injection into hypersonic airstreams and applications to ram C-3 flight

    NASA Technical Reports Server (NTRS)

    Weaver, W. L.

    1972-01-01

    Experimental data are presented for the oblique injection of water and three electrophilic liquids (fluorocarbon compounds) through multiple-orifice nozzles from a flat plate and the sides of a hemisphere-cone (0.375 scale of RAM C spacecraft) into hypersonic airstreams. The nozzle patterns included single and multiple orifices, single rows of nozzles, and duplicates of the RAM C-III nozzles. The flat-plate tests were made at Mach 8. Total pressure was varied from 3.45 MN/m2 to 10.34 MN/m2, Reynolds number was varied form 9,840,000 per meter to 19,700,000 per meter, and liquid injection pressure was varied from 0.69 MN/m2 to 3.5 MN/m2. The hemisphere-cone tests were made at Mach 7.3. Total pressure was varied from 1.38 MN/m2, to 6.89 MN/m2, Reynolds number was varied from 3,540,000 per meter to 17,700,000 per meter, and liquid-injection pressure was varied from 0.34 MN/m2 to 4.14 MN/m2. Photographs of the tests and plots of liquid-penetration and spray cross-section area are presented. Maximum penetration was found to vary as the square root of the dynamic-pressure ratio and the square root of the total injection nozzle area. Spray cross-section area was linear with maximum penetration. The test results are used to compute injection parameters for the RAM C-3 flight injection experiment.

  14. Surgical Repair of Mid-shaft Hypospadias Using a Transverse Preputial Island Flap and Pedicled Dartos Flap Around Urethral Orifice.

    PubMed

    Liang, Weiqiang; Ji, Chenyang; Chen, Yuhong; Zhang, Ganling; Zhang, Jiaqi; Yao, Yuanyuan; Zhang, Jinming

    2016-08-01

    To evaluate the effects, particularly the incidence of anastomotic fistula, of a pedicled dartos flap around the urethral orifice in the treatment of urethroplasty of mid-shaft hypospadias. A total of 46 cases of congenital mid-shaft hypospadias were included in this study. The patients ranged in age from 0.7 to 25.4 years and the average was 5.8 years. The patients received penis chordee correction. A transverse preputial island flap was developed for urethral reconstruction. The proximal dartos of the urethral orifice was used to develop a pedicled dartos flap, which was transposed to cover and strengthen neourethral anastomosis. The ventral penile skin defect was repaired by another flap. The 46 patients were examined during follow-up visits for 6 months to 3 years. An anastomotic fistula was observed in one case (2.2 %). Scar healing without fistula was observed in another patient due to poor blood supply to part of the ventral penile skin. No other incidences of fistula, urethral rupture, flap necrosis, wound infections, urinary tract (meatal) stenosis, or urethral diverticulum were observed in the patients. A pedicled dartos flap around the urethral orifice can take advantage of well-vascularized local tissue to add a protective layer to the proximal aspect of the neourethral anastomosis for reducing the incidence of anastomotic fistula in mid-shaft hypospadias repair using a transverse preputial island flap. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

  15. Development of Tasks and Evaluation of a Prototype Forceps for NOTES

    PubMed Central

    Addis, Matthew; Aguirre, Milton; Haluck, Randy; Matthew, Abraham; Pauli, Eric; Gopal, Jegan

    2012-01-01

    Background and Objectives: Few standardized testing procedures exist for instruments intended for Natural Orifice Translumenal Endoscopic Surgery. These testing procedures are critical for evaluating surgical skills and surgical instruments to ensure sufficient quality. This need is widely recognized by endoscopic surgeons as a major hurdle for the advancement of Natural Orifice Translumenal Endoscopic Surgery. Methods: Beginning with tasks currently used to evaluate laparoscopic surgeons and instruments, new tasks were designed to evaluate endoscopic surgical forceps instruments. Results: Six tasks have been developed from existing tasks, adapted and modified for use with endoscopic instruments, or newly designed to test additional features of endoscopic forceps. The new tasks include the Fuzzy Ball Task, Cup Drop Task, Ring Around Task, Material Pull Task, Simulated Biopsy Task, and the Force Gauge Task. These tasks were then used to evaluate the performance of a new forceps instrument designed at Pennsylvania State University. Conclusions: The need for testing procedures for the advancement of Natural Orifice Translumenal Endoscopic Surgery has been addressed in this work. The developed tasks form a basis for not only testing new forceps instruments, but also for evaluating individual performance of surgical candidates with endoscopic forceps instruments. PMID:22906337

  16. CFD study of a simple orifice pulse tube cooler

    NASA Astrophysics Data System (ADS)

    Zhang, X. B.; Qiu, L. M.; Gan, Z. H.; He, Y. L.

    2007-05-01

    Pulse tube cooler (PTC) has the advantages of long-life and low vibration over the conventional cryocoolers, such as G-M and Stirling coolers because of the absence of moving parts in low temperature. This paper performs a two-dimensional axis-symmetric computational fluid dynamic (CFD) simulation of a GM-type simple orifice PTC (OPTC). The detailed modeling process and the general results such as the phase difference between velocity and pressure at cold end, the temperature profiles along the wall as well as the temperature oscillations at cold end with different heat loads are presented. Emphases are put on analyzing the complicated phenomena of multi-dimensional flow and heat transfer in the pulse tube under conditions of oscillating pressure. Swirling flow pattern in the pulse tube is observed and the mechanism of formation is analyzed in details, which is further validated by modeling a basic PTC. The swirl causes undesirable mixing in the thermally stratified fluid and is partially responsible for the poor overall performance of the cooler, such as unsteady cold-end temperature.

  17. Air-surface exchange measurements of gaseous elemental mercury over naturally enriched and background terrestrial landscapes in Australia

    NASA Astrophysics Data System (ADS)

    Edwards, G. C.; Howard, D. A.

    2013-05-01

    This paper presents the first gaseous elemental mercury (GEM) air-surface exchange measurements obtained over naturally enriched and background (<0.1 μg g-1 Hg) terrestrial landscapes in Australia. Two pilot field studies were carried out during the Australian autumn and winter periods at a copper-gold-cobalt-arsenic-mercury mineral field near Pulganbar, NSW. GEM fluxes using a dynamic flux chamber approach were measured, along with controlling environmental parameters over three naturally enriched and three background substrates. The enriched sites results showed net emission to the atmosphere and a strong correlation between flux and substrate Hg concentration, with average fluxes ranging from 14 ± 1 ng m-2 h-1 to 113 ± 6 ng m-2 h-1. Measurements at background sites showed both emission and deposition. The average Hg flux from all background sites showed an overall net emission of 0.36 ± 0.06 ng m-2 h-1. Fluxes show strong relationships with temperature, radiation, and substrate parameters. A compensation point of 2.48, representative of bare soils was determined. For periods of deposition, dry deposition velocities ranged from 0.00025 cm s-1 to 0.0083 cm s-1 with an average of 0.0041 ± 0.00018 cm s-1, representing bare soil, nighttime conditions. Comparison of the Australian data to North American data suggests the need for Australian-specific mercury air-surface exchange data representative of Australia's unique climatic conditions, vegetation types, land use patterns and soils.

  18. Estimating COCOM Natural Background Dormancy

    DTIC Science & Technology

    2015-04-01

    Goode and Espenshade 1953). Maps from Goode’s World Atlas included natural vegetation, agricultural regions, and soils . Clark University provided...and shallow, high mountain soils (Chambers 1967). The vertical stripes indi- cate a probability of more than two weeks of snow cover during the month...needle-leaf evergreen and deciduous trees during dormant or dry season, and desert alluvial deposits, sand, and thin mountain soils 6 Needle-leaf

  19. The Effect of Orifice Eccentricity on Instability of Liquid Jets

    NASA Astrophysics Data System (ADS)

    Amini, Ghobad; Dolatabadi, Ali

    2011-11-01

    The hydrodynamic instability of inviscid jets issuing from elliptic orifices is studied. A linear stability analysis is presented for liquid jets that includes the effect of the surrounding gas and an explicit dispersion equation is derived for waves on an infinite uniform jet column. Elliptic configuration has two extreme cases; round jet when ratio of minor to major axis is unity and plane sheet when this ratio approaches zero. Dispersion equation of elliptic jet is approximated for large and small aspect ratios considering asymptotic of the dispersion equation. In case of aspect ratio equal to one, the dispersion equation is analogous to one of the circular jets derived by Yang. In case of aspect ratio approaches zero, the behavior of waves is qualitatively similar to that of long waves on a two dimensional liquid jets and the varicose and sinuous modes are predicted. The growth rate of initial disturbances for various azimuthal modes has been presented in a wide range of disturbances. PhD Candidate.

  20. Survival study of natural orifice translumenal endoscopic surgery for rectosigmoid resection using transanal endoscopic microsurgery with or without transgastric endoscopic assistance in a swine model.

    PubMed

    Sylla, Patricia; Sohn, Dae Kyung; Cizginer, Sevdenur; Konuk, Yusuf; Turner, Brian G; Gee, Denise W; Willingham, Field F; Hsu, Maylee; Mino-Kenudson, Mari; Brugge, William R; Rattner, David W

    2010-08-01

    The feasibility of transanal rectosigmoid resection with transanal endoscopic microsurgery (TEM) was previously demonstrated in a swine nonsurvival model in which transgastric endoscopic assistance also was shown to extend the length of colon mobilized transanally. A 2-week survival study evaluating transanal endoscopic rectosigmoid resection with stapled colorectal anastomosis was conducted with swine using the transanal approach alone (TEM group, n = 10) or a transanal approach combined with transgastric endoscopic assistance (TEM + TG group, n = 10). Gastrotomies were created using a needleknife and balloon dilation, then closed using prototype T-tags. Outcomes were evaluated and compared between the groups using Student's t-test and Fisher's exact test. Relative to the TEM group, the average length of rectosigmoid mobilized in the TEM + TG group was 15.6 versus 10.5 cm (p < 0.0005), the length of the resected specimen was 9 versus 6.2 cm (p < 0.0005), and the mean operative time was 254.5 versus 97.5 min (p < 0.0005). Intraoperatively, no organ injury or major bleeding was noted. Two T-tag misfires occurred during gastrotomy closure and four small staple line defects requiring transanal repair including one in the TEM group and three in the TEM + TG group (p = 0.2). Postoperatively, there was no mortality, and the animals gained an average of 3.4 lb. Two major complications (10%) were identified at necropsy in the TEM + TG group including an intraabdominal abscess and an abdominal wall hematoma related to T-tag misfire. Gastrotomy closure sites and colorectal anastomoses were all grossly healed, with adhesions noted in 60 and 70% and microabscesses in 50 and 20% of the gastrotomy sites and colorectal anastomoses, respectively. Natural orifice translumenal endoscopic surgery (NOTES) for rectosigmoid resection using TEM with or without transgastric endoscopic assistance is feasible and associated with low morbidity in a porcine survival model. Transgastric

  1. In situ monitoring of tracer tests: how to distinguish tracer recovery from natural background

    NASA Astrophysics Data System (ADS)

    Bailly-Comte, V.; Durepaire, X.; Batiot-Guilhe, C.; Schnegg, P.-A.

    2018-03-01

    Hydrogeological tracer tests are primarily conducted with fluorescent tracers. Field fluorometers make it possible to monitor tracers at very low concentrations (<1 ppb) and at high frequency. However, changes in natural fluorescence at a site resulting from variations of dissolved and suspended inorganic and organic material may compromise the measurement of useful signals, thereby limiting the chances of identifying or quantifying the real tracer recovery. An elevated natural signal can mask small concentrations of the tracer while its variability can give the impression of a false recovery. This article shows how the use of a combination of several continuous measurements at different wavelengths allows a better extraction of the natural signal. Field multispectral fluorometers were installed at two Mediterranean karst outlets; both drain carbonate systems but have different environmental conditions. The fluorometers functioned over several hydrologic cycles, in periods affected or not by artificial tracers, making it possible to observe natural signal variations at these sites. The optical properties of this type of field fluorometer were used to calculate the spectral response of the different optics of the measuring probe. These responses, superimposed on three-dimensional excitation/emission matrices produced from laboratory fluorescence measurements, allowed an understanding of what the fluorometer sees under natural flow conditions. The result is an innovative method for correcting artificial tracer results. This type of correction makes it possible to fine-tune the effect of natural background variation on tracer recovery curves for a clear identification of the tracer presence and a more precise quantification of its recovery.

  2. Mass flow rate measurements in gas-liquid flows by means of a venturi or orifice plate coupled to a void fraction sensor

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Oliveira, Jorge Luiz Goes; Passos, Julio Cesar; Verschaeren, Ruud

    Two-phase flow measurements were carried out using a resistive void fraction meter coupled to a venturi or orifice plate. The measurement system used to estimate the liquid and gas mass flow rates was evaluated using an air-water experimental facility. Experiments included upward vertical and horizontal flow, annular, bubbly, churn and slug patterns, void fraction ranging from 2% to 85%, water flow rate up to 4000 kg/h, air flow rate up to 50 kg/h, and quality up to almost 10%. The fractional root mean square (RMS) deviation of the two-phase mass flow rate in upward vertical flow through a venturi platemore » is 6.8% using the correlation of Chisholm (D. Chisholm, Pressure gradients during the flow of incompressible two-phase mixtures through pipes, venturis and orifice plates, British Chemical Engineering 12 (9) (1967) 454-457). For the orifice plate, the RMS deviation of the vertical flow is 5.5% using the correlation of Zhang et al. (H.J. Zhang, W.T. Yue, Z.Y. Huang, Investigation of oil-air two-phase mass flow rate measurement using venturi and void fraction sensor, Journal of Zhejiang University Science 6A (6) (2005) 601-606). The results show that the flow direction has no significant influence on the meters in relation to the pressure drop in the experimental operation range. Quality and slip ratio analyses were also performed. The results show a mean slip ratio lower than 1.1, when bubbly and slug flow patterns are encountered for mean void fractions lower than 70%. (author)« less

  3. Totally laparoscopic resection with natural orifice specimen extraction (NOSE) has more advantages comparing with laparoscopic-assisted resection for selected patients with sigmoid colon or rectal cancer.

    PubMed

    Xingmao, Zhang; Haitao, Zhou; Jianwei, Liang; Huirong, Hou; Junjie, Hu; Zhixiang, Zhou

    2014-09-01

    The purposes of this study were to compare the short-term outcomes of natural orifice specimen extraction (NOSE) and laparoscopic-assisted resection for sigmoid colon cancer or rectal cancer and to appraise whether totally laparoscopic resection with NOSE had more advantages compared with conventional laparoscopic-assisted resection. Sixty-five patients who underwent totally laparoscopic resection with NOSE were assigned to NOSE group, and 132 patients who underwent laparoscopic-assisted resection were assigned to laparoscopic-assisted (LA) group. Data of all 197 cases were reviewed. Short-term outcomes (including operative outcomes, gastrointestinal recovery, hospital stay, and complication) of the two groups were compared. Mean numbers of lymph nodes harvested were 17.0 ± 8.3 and 18.9 ± 11.6 in NOSE group and LA group, respectively, (P = 0.248); mean operative times were 111.6 ± 25.4 min and 115.3 ± 23.0 min in the two groups (P = 0.384); and the mean blood losses in these two groups were 70.2 ± 66.1 ml and 126.3 ± 58.6 ml, respectively, (P < 0.001). Times to first flatus were 2.7 ± 0.8 and 3.4 ± 0.9 days (P < 0.001), and times to first defecation were 3.3 ± 0.6 and 3.9 ± 1.1 days (P = 0.002) in NOSE group and LA group, respectively. Hospital stay in NOSE group were 9.0 ± 1.9 and 9.9 ± 2.0 days in LA group. Incidences of peri-operative complications were 6.2 and 17.2% in the two groups, respectively (P = 0.031). Without compromising oncologic outcome, totally laparoscopic resection with NOSE had more advantages including less blood loss, less pain, faster recovery of intestinal function and shorter hospital stay compared with laparoscopic-assisted resection for selected patients with sigmoid colon cancer or rectal cancer.

  4. Ultra-minimally invasive local immune cell therapy and regenerative therapy by multi-piercing surgery for abdominal solid tumor: therapeutic simulation by natural orifice translumenal endoscopic surgery-assisted needlescopic surgery using 3-mm diameter robots.

    PubMed

    Ohdaira, Takeshi; Tsutsumi, Norifumi; Xu, Hao; Mori, Megumu; Uemura, Munenori; Ieiri, Satoshi; Hashizume, Makoto

    2011-07-01

    We have invented multi-piercing surgery (MPS) which could potentially solve the triangular formation loss and device clashing which occur in single-port surgery (SPS), as well as restricted visual field, organ damage by needle-type instruments, and impaired removal of a resected organ from the body which occur in needlescopic surgery (NS). MPS is natural orifice translumenal endoscopic surgery (NOTES)-assisted NS. We used 3-mm diameter robots as needle-type instruments for MPS to examine the possibility of local immune cell therapy and regenerative therapy using stem cells for pancreatic cancer. In MPS using two robots, the therapeutic cell suspension was injected into a target region of pancreas in two pigs. Both retention of a capsule of liquid cell suspension and invasive level were evaluated. Triangular formation could be ensured. The use of small-diameter robots allowed (1) the surgical separation of the pancreas and the retroperitoneum, and (2) the formation of the capsule containing the immune cell and stem cell suspension. The endoscope for NOTES provided a clear visual field and also assisted the removal of a resected organ from the body. The visual field of the endoscope could be oriented well by using an electromagnetic navigation system. MPS using small-diameter robots could potentially solve the issues inherent in SPS and NS and could allow minimally invasive local immune cell and stem cell therapy.

  5. Cardiac valve orifice equation independent of valvular flow intervals: application to mitral valve area computation in mitral stenosis and comparison with the Gorlin formula and direct anatomical measurements.

    PubMed

    Seitz, W; Marino, P; Zanolla, L; Buonanno, C; McIlroy, M; Spiel, M

    1984-11-01

    An orifice equation is developed which relates the effective mitral valve area (A), the average mitral valve pressure gradient (dP), the cardiac output (Q) and the heart frequency (f) through considerations of momentum conservation across the mitral valve. The form of the new equation is A = (4.75 X 10(-5)Qf/dP, where A, Q, and dP are expressed in cm2, ml X min-1 and mmHg respectively. Mitral valve areas computed with the new orifice formula are found to correlate with those computed by the Gorlin formula in conditions of equilibrium associated with the resting state at a level of r = 0.95, SE = 0.15 cm2, with autopsy measurements at a level of r = 0.85, SE = 0.18 cm2 and with direct anatomical measurements of excised valves at a level of r = 0.78, SE = 0.41 cm2. The results suggest that the new formula may be considered as an independent orifice equation enjoying a similar domain of validity as the Gorlin formula. The new equation offers the possibility of deriving additional useful haemodynamic relationships when used in combination with established cardiological formulas.

  6. Natural background levels and threshold values for groundwater in fluvial Pleistocene and Tertiary marine aquifers in Flanders, Belgium

    NASA Astrophysics Data System (ADS)

    Coetsiers, Marleen; Blaser, Petra; Martens, Kristine; Walraevens, Kristine

    2009-05-01

    Aquifers from the same typology can have strongly different groundwater chemistry. Deducing the groundwater quality of less well-characterized aquifers from well-documented aquifers belonging to the same typology should be done with great reserve, and can only be considered as a preliminary approach. In the EU’s 6th FP BRIDGE project “Background cRiteria for the IDentification of Groundwater thrEsholds”, a methodology for the derivation of threshold values (TV) for groundwater bodies is proposed. This methodology is tested on four aquifers in Flanders of the sand and gravel typology. The methodology works well for all but the Ledo-Paniselian aquifer, where the subdivision into a fresh and saline part is disproved, as a gradual natural transition from fresh to saline conditions in the aquifer is observed. The 90 percentile is proposed as natural background level (NBL) for the unconfined Pleistocene deposits, ascribing the outliers to possible influence of pollution. For the Tertiary aquifers, high values for different parameters have a natural origin and the 97.7 percentile is preferred as NBL. The methodology leads to high TVs for parameters presenting low NBL, when compared to the standard used as a reference. This would allow for substantial anthropogenic inputs of these parameters.

  7. Influence of the tilt angle of Percutaneous Aortic Prosthesis on Velocity and Shear Stress Fields

    PubMed Central

    Gomes, Bruno Alvares de Azevedo; Camargo, Gabriel Cordeiro; dos Santos, Jorge Roberto Lopes; Azevedo, Luis Fernando Alzuguir; Nieckele, Ângela Ourivio; Siqueira-Filho, Aristarco Gonçalves; de Oliveira, Glaucia Maria Moraes

    2017-01-01

    Background Due to the nature of the percutaneous prosthesis deployment process, a variation in its final position is expected. Prosthetic valve placement will define the spatial location of its effective orifice in relation to the aortic annulus. The blood flow pattern in the ascending aorta is related to the aortic remodeling process, and depends on the spatial location of the effective orifice. The hemodynamic effect of small variations in the angle of inclination of the effective orifice has not been studied in detail. Objective To implement an in vitro simulation to characterize the hydrodynamic blood flow pattern associated with small variations in the effective orifice inclination. Methods A three-dimensional aortic phantom was constructed, reproducing the anatomy of one patient submitted to percutaneous aortic valve implantation. Flow analysis was performed by use of the Particle Image Velocimetry technique. The flow pattern in the ascending aorta was characterized for six flow rate levels. In addition, six angles of inclination of the effective orifice were assessed. Results The effective orifice at the -4º and -2º angles directed the main flow towards the anterior wall of the aortic model, inducing asymmetric and high shear stress in that region. However, the effective orifice at the +3º and +5º angles mimics the physiological pattern, centralizing the main flow and promoting a symmetric distribution of shear stress. Conclusion The measurements performed suggest that small changes in the angle of inclination of the percutaneous prosthesis aid in the generation of a physiological hemodynamic pattern, and can contribute to reduce aortic remodeling. PMID:28793046

  8. The Colour of Velvet. A Transdisciplinary Approach to Connecting Students from a Refugee Background to the Natural World

    ERIC Educational Resources Information Center

    Brown, Leni; O'Keefe, Lise; Paige, Kathryn

    2017-01-01

    What pedagogical strategies support students from a refugee background connecting to the natural world? What would these strategies look like for fifteen students participating in a language intensive New Arrivals Program (NAP)? These questions were the focus of a small collaborative project set up to investigate the impact of pedagogical…

  9. Further insights into normal aortic valve function: role of a compliant aortic root on leaflet opening and valve orifice area.

    PubMed

    Sripathi, Vangipuram Canchi; Kumar, Ramarathnam Krishna; Balakrishnan, Komarakshi R

    2004-03-01

    This study aims to find the fundamental differences in the mechanism of opening and closing of a normal aortic valve and a valve with a stiff root, using a dynamic finite element model. A dynamic, finite element model with time varying pressure was used in this study. Shell elements with linear elastic properties for the leaflet and root were used. Two different cases were analyzed: (1) normal leaflets inside a compliant root, and (2) normal leaflets inside a stiff root. A compliant aortic root contributes substantially to the smooth and symmetrical leaflet opening with minimal gradients. In contrast, the leaflet opening inside a stiff root is delayed, asymmetric, and wrinkled. However, this wrinkling is not associated with increased leaflet stresses. In compliant roots, the effective valve orifice area can substantially increase because of increased root pressure and transvalvular gradients. In stiff roots this effect is strikingly absent. A compliant aortic root contributes substantially to smooth and symmetrical leaflet opening with minimal gradients. The compliance also contributes much to the ability of the normal aortic valve to increase its effective valve orifice in response to physiologic demands of exercise. This effect is strikingly absent in stiff roots.

  10. Waiting time effect of a GM type orifice pulse tube refrigerator

    NASA Astrophysics Data System (ADS)

    Zhu, Shaowei; Kakimi, Yasuhiro; Matsubara, Yoichi

    In a general GM type orifice pulse tube refrigerator, there are two short periods during which both the high pressure valve and the low pressure valve are closed in one cycle. We call the short period `waiting time'. The pressure differences across the high pressure valve and the low pressure valve are decreased by using long waiting time. The pressure difference loss is decreased. Thus, the cooling capacity and the efficiency are increased, and the no-load temperature is decreased. The mechanism of the waiting time is discussed with numerical analysis and verified by experiments. Experiments show that there is an optimum waiting time for the no-load temperature, the cooling capacity and the efficiency, respectively. The no-load temperature of 40.3 K was achieved with a 90° waiting time. The cooling capacity of 58 W at 80 K was achieved with a 60° waiting time. The no-load temperature of 45.1 K and the cooling capacity of 45 W at 80 K were achieved with a 1° waiting time.

  11. Educational and training aspects of new surgical techniques: experience with the endoscopic–laparoscopic interdisciplinary training entity (ELITE) model in training for a natural orifice translumenal endoscopic surgery (NOTES) approach to appendectomy.

    PubMed

    Gillen, Sonja; Gröne, Jörn; Knödgen, Fritz; Wolf, Petra; Meyer, Michael; Friess, Helmut; Buhr, Heinz-Johannes; Ritz, Jörg-Peter; Feussner, Hubertus; Lehmann, Kai S

    2012-08-01

    Natural orifice translumenal endoscopic surgery (NOTES) is a new surgical concept that requires training before it is introduced into clinical practice. The endoscopic–laparoscopic interdisciplinary training entity (ELITE) is a training model for NOTES interventions. The latest research has concentrated on new materials for organs with realistic optical and haptic characteristics and the possibility of high-frequency dissection. This study aimed to assess both the ELITE model in a surgical training course and the construct validity of a newly developed NOTES appendectomy scenario. The 70 attendees of the 2010 Practical Course for Visceral Surgery (Warnemuende, Germany) took part in the study and performed a NOTES appendectomy via a transsigmoidal access. The primary end point was the total time required for the appendectomy, including retrieval of the appendix. Subjective evaluation of the model was performed using a questionnaire. Subgroups were analyzed according to laparoscopic and endoscopic experience. The participants with endoscopic or laparoscopic experience completed the task significantly faster than the inexperienced participants (p = 0.009 and 0.019, respectively). Endoscopic experience was the strongest influencing factor, whereas laparoscopic experience had limited impact on the participants with previous endoscopic experience. As shown by the findings, 87.3% of the participants stated that the ELITE model was suitable for the NOTES training scenario, and 88.7% found the newly developed model anatomically realistic. This study was able to establish face and construct validity for the ELITE model with a large group of surgeons. The ELITE model seems to be well suited for the training of NOTES as a new surgical technique in an established gastrointestinal surgery skills course.

  12. Computation of Transverse Injection Into Supersonic Crossflow With Various Injector Orifice Geometries

    NASA Technical Reports Server (NTRS)

    Foster, Lancert; Engblom, William A.

    2003-01-01

    Computational results are presented for the performance and flow behavior of various injector geometries employed in transverse injection into a non-reacting Mach 1.2 flow. 3-D Reynolds-Averaged Navier Stokes (RANS) results are obtained for the various injector geometries using the Wind code with the Mentor s Shear Stress Transport turbulence model in both single and multi-species modes. Computed results for the injector mixing, penetration, and induced wall forces are presented. In the case of rectangular injectors, those longer in the direction of the freestream flow are predicted to generate the most mixing and penetration of the injector flow into the primary stream. These injectors are also predicted to provide the largest discharge coefficients and induced wall forces. Minor performance differences are indicated among diamond, circle, and square orifices. Grid sensitivity study results are presented which indicate consistent qualitative trends in the injector performance comparisons with increasing grid fineness.

  13. Natural 'background' soil water repellency in conifer forests: its prediction and relationship to wildfire occurrence

    NASA Astrophysics Data System (ADS)

    Doerr, Stefan; Woods, Scott; Martin, Deborah; Casimiro, Marta

    2013-04-01

    Soils under a wide range of vegetation types exhibit water repellency following the passage of a fire. This is viewed by many as one of the main causes for accelerated post-fire runoff and soil erosion and it has often been assumed that strong soil water repellency present after wildfire is fire-induced. However, high levels of repellency have also been reported under vegetation types not affected by fire, and the question arises to what degree the water repellency observed at burnt sites actually results from fire. This study aimed at determining 'natural background' water repellency in common coniferous forest types in the north-western USA. Mature or semi-mature coniferous forest sites (n = 81), which showed no evidence of recent fires and had at least some needle cast cover, were sampled across six states. After careful removal of litter and duff at each site, soil water repellency was examined in situ at the mineral soil surface using the Water Drop Penetration Time (WDPT) method for three sub-sites, followed by col- lecting near-surface mineral soil layer samples (0-3 cm depth). Following air-drying, samples were fur- ther analyzed for repellency using WDPT and contact angle (hsl) measurements. Amongst other variables examined were dominant tree type, ground vegetation, litter and duff layer depth, slope angle and aspect, elevation, geology, and soil texture, organic carbon content and pH. 'Natural background' water repellency (WDPT > 5 s) was detected in situ and on air-dry samples at 75% of all sites examined irrespective of dominant tree species (Pinus ponderosa, Pinus contorta, Picea engelma- nii and Pseudotsuga menziesii). These findings demonstrate that the soil water repellency commonly observed in these forest types following burning is not necessarily the result of recent fire but can instead be a natural characteristic. The notion of a low background water repellency being typical for long- unburnt conifer forest soils of the north-western USA is

  14. Multiple factors impact the contents of heavy metals in vegetables in high natural background area of China.

    PubMed

    Gan, Yandong; Wang, Lihong; Yang, Guiqiang; Dai, Jiulan; Wang, Renqing; Wang, Wenxing

    2017-10-01

    A field survey was conducted to investigate the concentrations of chromium (Cr), nickel (Ni), copper (Cu), zinc (Zn), cadmium (Cd) and lead (Pb) in vegetables, corresponding cultivated soils and irrigation waters from 36 open sites in high natural background area of Wuzhou, South China. Redundancy analysis, Spearman's rho correlation analysis and multiple regression analysis were adopted to evaluate the contributions of impacting factors on metal contents in the edible parts of vegetables. This study concluded that leafy and root vegetables had relatively higher metal concentrations and adjusted transfer factor values compared to fruiting vegetables according to nonparametric tests. Plant species, total soil metal content and soil pH value were affirmed as three critical factors with the highest contribution rate among all the influencing factors. The bivariate curve equation models for heavy metals in the edible vegetable tissues were well fitted to predict the metal concentrations in vegetables. The results from this case study also suggested that it could be one of efficient strategies for clean agricultural production and food safety in high natural background area to breed vegetable varieties with low heavy metal accumulation and to enlarge planting scale of these varieties. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Quality assurance of temporal variability of natural decay chain and neutron induced background for low-level NORM analysis

    DOE PAGES

    Yoho, Michael; Porterfield, Donivan R.; Landsberger, Sheldon

    2015-09-22

    In this study, twenty-one high purity germanium (HPGe) background spectra were collected over 2 years at Los Alamos National Laboratory. A quality assurance methodology was developed to monitor spectral background levels from thermal and fast neutron flux levels and naturally occurring radioactive material decay series radionuclides. 238U decay products above 222Rn demonstrated minimal temporal variability beyond that expected from counting statistics. 238U and 232Th progeny below Rn gas displayed at most twice the expected variability. Further, an analysis of the 139 keV 74Ge(n, γ) and 691 keV 72Ge(n, n') spectral features demonstrated temporal stability for both thermal and fastmore » neutron fluxes.« less

  16. Experimental investigation of the effect orifice shape and fluid pressure has on high aspect ratio cross-sectional jet behaviour.

    PubMed

    Wakes, S J; Holdø, A E; Meares, A J

    2002-01-04

    Prevention of major disasters such as Piper Alpha is a concern of oil and gas companies when commissioning a new offshore superstructure. Safety studies are undertaken to identify potential major hazards, risks to personnel and that sufficient precautions have been employed to minimise these. Such an assessment will also include the consideration of the protection from gas leaks such as the optimum positions of gas leak detectors and startup safety procedures after a leak. This requires a comprehensive knowledge of the behaviour of the leaking hydrocarbons as they emerge from the leak into the area of concern. Such leaks are most likely to emanate from a high aspect ratio cross-sectional curved slot in a pipeline. This paper challenges the conventional view that it is sufficient to model such leaks as axisymmetric jets. This paper is therefore concerned with an experimental study carried out on a series of more realistic high aspect ratio cross-sectional jets issuing from a flange orifice. Both high quality photographs in both planes of the jets and some quantitative pressure data is examined for a high aspect ratio cross-sectional jet of air at pressures up to 4.136bar. The effect of changing aspect ratio, fluid pressure and orifice shape will be discussed and put into context with regard to how this relates to offshore analysis studies.

  17. Residential Exposure to Natural Background Radiation and Risk of Childhood Acute Leukemia in France, 1990–2009

    PubMed Central

    Demoury, Claire; Marquant, Fabienne; Ielsch, Géraldine; Goujon, Stéphanie; Debayle, Christophe; Faure, Laure; Coste, Astrid; Laurent, Olivier; Guillevic, Jérôme; Laurier, Dominique; Hémon, Denis; Clavel, Jacqueline

    2016-01-01

    Background: Exposures to high-dose ionizing radiation and high-dose rate ionizing radiation are established risk factors for childhood acute leukemia (AL). The risk of AL following exposure to lower doses due to natural background radiation (NBR) has yet to be conclusively determined. Methods: AL cases diagnosed over 1990–2009 (9,056 cases) were identified and their municipality of residence at diagnosis collected by the National Registry of Childhood Cancers. The Geocap study, which included the 2,763 cases in 2002–2007 and 30,000 population controls, was used for complementary analyses. NBR exposures were modeled on a fine scale (36,326 municipalities) based on measurement campaigns and geological data. The power to detect an association between AL and dose to the red bone marrow (RBM) fitting UNSCEAR (United Nations Scientific Committee on the Effects of Atomic Radiation) predictions was 92%, 45% and 99% for exposure to natural gamma radiation, radon and total radiation, respectively. Results: AL risk, irrespective of subtype and age group, was not associated with the exposure of municipalities to radon or gamma radiation in terms of yearly exposure at age reached, cumulative exposure or RBM dose. There was no confounding effect of census-based socio-demographic indicators, or environmental factors (road traffic, high voltage power lines, vicinity of nuclear plants) related to AL in the Geocap study. Conclusions: Our findings do not support the hypothesis that residential exposure to NBR increases the risk of AL, despite the large size of the study, fine scale exposure estimates and wide range of exposures over France. However, our results at the time of diagnosis do not rule out a slight association with gamma radiation at the time of birth, which would be more in line with the recent findings in the UK and Switzerland. Citation: Demoury C, Marquant F, Ielsch G, Goujon S, Debayle C, Faure L, Coste A, Laurent O, Guillevic J, Laurier D, Hémon D, Clavel J

  18. Measurements of Thermal Effects on Acoustic Screech in a Choked Circular Jet Emanating from a Sharp-Edged Orifice

    NASA Technical Reports Server (NTRS)

    Kandula, Max

    2012-01-01

    Experiments are performed in a 24.4 mm diameter choked circular hot and cold jets issuing from a sharp-edged orifice at a fully expanded jet Mach number of 1.85. The stagnation temperature of the hot and the cold jets are 319 K and 299 K respectively. The results suggest that temperature effects on the screech amplitude and frequency are manifested for the fundamental, with a reduced amplitude and increased frequency for hot jet relative to the cold jet. Temperature effects on the second harmonic are also observed.

  19. Naturally occurring 32Si and low-background silicon dark matter detectors

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Orrell, John L.; Arnquist, Isaac J.; Bliss, Mary

    Here, the naturally occurring radioisotope 32Si represents a potentially limiting background in future dark matter direct-detection experiments. We investigate sources of 32Si and the vectors by which it comes to reside in silicon crystals used for fabrication of radiation detectors. We infer that the 32Si concentration in commercial single-crystal silicon is likely variable, dependent upon the specific geologic and hydrologic history of the source (or sources) of silicon “ore” and the details of the silicon-refinement process. The silicon production industry is large, highly segmented by refining step, and multifaceted in terms of final product type, from which we conclude thatmore » production of 32Si-mitigated crystals requires both targeted silicon material selection and a dedicated refinement-through-crystal-production process. We review options for source material selection, including quartz from an underground source and silicon isotopically reduced in 32Si. To quantitatively evaluate the 32Si content in silicon metal and precursor materials, we propose analytic methods employing chemical processing and radiometric measurements. Ultimately, it appears feasible to produce silicon detectors with low levels of 32Si, though significant assay method development is required to validate this claim and thereby enable a quality assurance program during an actual controlled silicon-detector production cycle.« less

  20. Naturally occurring 32Si and low-background silicon dark matter detectors

    DOE PAGES

    Orrell, John L.; Arnquist, Isaac J.; Bliss, Mary; ...

    2018-02-10

    Here, the naturally occurring radioisotope 32Si represents a potentially limiting background in future dark matter direct-detection experiments. We investigate sources of 32Si and the vectors by which it comes to reside in silicon crystals used for fabrication of radiation detectors. We infer that the 32Si concentration in commercial single-crystal silicon is likely variable, dependent upon the specific geologic and hydrologic history of the source (or sources) of silicon “ore” and the details of the silicon-refinement process. The silicon production industry is large, highly segmented by refining step, and multifaceted in terms of final product type, from which we conclude thatmore » production of 32Si-mitigated crystals requires both targeted silicon material selection and a dedicated refinement-through-crystal-production process. We review options for source material selection, including quartz from an underground source and silicon isotopically reduced in 32Si. To quantitatively evaluate the 32Si content in silicon metal and precursor materials, we propose analytic methods employing chemical processing and radiometric measurements. Ultimately, it appears feasible to produce silicon detectors with low levels of 32Si, though significant assay method development is required to validate this claim and thereby enable a quality assurance program during an actual controlled silicon-detector production cycle.« less

  1. Naturally occurring 32Si and low-background silicon dark matter detectors

    NASA Astrophysics Data System (ADS)

    Orrell, John L.; Arnquist, Isaac J.; Bliss, Mary; Bunker, Raymond; Finch, Zachary S.

    2018-05-01

    The naturally occurring radioisotope 32Si represents a potentially limiting background in future dark matter direct-detection experiments. We investigate sources of 32Si and the vectors by which it comes to reside in silicon crystals used for fabrication of radiation detectors. We infer that the 32Si concentration in commercial single-crystal silicon is likely variable, dependent upon the specific geologic and hydrologic history of the source (or sources) of silicon "ore" and the details of the silicon-refinement process. The silicon production industry is large, highly segmented by refining step, and multifaceted in terms of final product type, from which we conclude that production of 32Si-mitigated crystals requires both targeted silicon material selection and a dedicated refinement-through-crystal-production process. We review options for source material selection, including quartz from an underground source and silicon isotopically reduced in 32Si. To quantitatively evaluate the 32Si content in silicon metal and precursor materials, we propose analytic methods employing chemical processing and radiometric measurements. Ultimately, it appears feasible to produce silicon detectors with low levels of 32Si, though significant assay method development is required to validate this claim and thereby enable a quality assurance program during an actual controlled silicon-detector production cycle.

  2. Naturally occurring 32 Si and low-background silicon dark matter detectors

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Orrell, John L.; Arnquist, Isaac J.; Bliss, Mary

    The naturally occurring radioisotope Si-32 represents a potentially limiting background in future dark matter direct-detection experiments. We investigate sources of Si-32 and the vectors by which it comes to reside in silicon crystals used for fabrication of radiation detectors. We infer that the Si-32 concentration in commercial single-crystal silicon is likely variable, dependent upon the specific geologic and hydrologic history of the source (or sources) of silicon “ore” and the details of the silicon-refinement process. The silicon production industry is large, highly segmented by refining step, and multifaceted in terms of final product type, from which we conclude that productionmore » of Si-32-mitigated crystals requires both targeted silicon material selection and a dedicated refinement-through-crystal-production process. We review options for source material selection, including quartz from an underground source and silicon isotopically reduced in Si-32. To quantitatively evaluate the Si-32 content in silicon metal and precursor materials, we propose analytic methods employing chemical processing and radiometric measurements. Ultimately, it appears feasible to produce silicon-based detectors with low levels of Si-32, though significant assay method development is required to validate this claim and thereby enable a quality assurance program during an actual controlled silicon-detector production cycle.« less

  3. Investigation of dielectric constant variations for Malaysians soil species towards its natural background dose

    NASA Astrophysics Data System (ADS)

    Jafery, Khawarizmi Mohd; Embong, Zaidi; Khee, Yee See; Haimi Dahlan, Samsul; Tajudin, Saiful Azhar Ahmad; Ahmad, Salawati; Kudnie Sahari, Siti; Maxwell, Omeje

    2018-01-01

    The correlation of natural background gamma radiation and real part of the complex relative permittivity (dielectric constant) for various species Malaysian soils was investigated in this research. The sampling sites were chosen randomly according to soils groups that consist of sedentary, alluvial and miscellaneous soil which covered the area of Batu Pahat, Kluang and Johor Bahru, Johor state of Malaysia. There are 11 types of Malaysian soil species that have been studied; namely Peat, Linau-Sedu, Selangor-Kangkong, Kranji, Telemong-Akob-Local Alluvium, Holyrood-Lunas, Batu Anam-Melaka-Tavy, Harimau Tampoi, Kulai-Yong Peng, Rengam-Jerangau, and Steepland soils. In-situ exposure rates of each soil species were measured by using portable gamma survey meter and ex-situ analysis of real part of relative permittivity was performed by using DAK (Dielectric Assessment Kit assist by network analyser). Results revealed that the highest and the lowest background dose rate were 94 ± 26.28 μR hr-1 and 7 ± 0.67 μR hr-1 contributed by Rengam Jerangau and Peat soil species respectively. Meanwhile, dielectric constant measurement, it was performed in the range of frequency between 100 MHz to 3 GHz. The measurements of each soils species dielectric constant are in the range of 1 to 3. At the lower frequencies in the range of 100 MHz to 600 MHz, it was observed that the dielectric constant for each soil species fluctuated and inconsistent. But it remained consistent in plateau form of signal at higher frequency at range above 600 MHz. From the comparison of dielectric properties of each soil at above 600 MHz of frequency, it was found that Rengam-Jerangau soil species give the highest reading and followed by Selangor-Kangkong species. The average dielectric measurement for both Selangor-Kangkong and Rengam-Jerangau soil species are 2.34 and 2.35 respectively. Meanwhile, peat soil species exhibits the lowest dielectric measurement of 1.83. It can be clearly seen that the pattern

  4. Background in X-ray astronomy proportional counters

    NASA Technical Reports Server (NTRS)

    Bower, C. R.; Dietz, K. L.; Ramsey, B. D.; Weisskopf, M. C.

    1991-01-01

    The authors report the results of an investigation into the nature of background events in proportional counters sensitive to X-ray photons having energy of less than 150 keV. Even with the use of thick shields composed of high-atomic-number material, a significant flux background in the detector's energy region can result from multiple Compton scattering in the mass surrounding the active region of the detector. The importance of the selection of detector components in the reduction of the background by more than an order of magnitude is emphasized. Experimental results are shown to agree qualitatively with Monte Carlo simulations. It is concluded that escape gating is a powerful means of determining the nature of background in flight detectors: the single/pair ratios reveal whether the detected events are charged particles or photons.

  5. The interaction of natural background gamma radiation with depleted uranium micro-particles in the human body.

    PubMed

    Pattison, John E

    2013-03-01

    In this study, some characteristics of the photo-electrons produced when natural background gamma radiation interacts with micron-sized depleted uranium (DU) particles in the human body have been estimated using Monte Carlo simulations. In addition, an estimate has been made of the likelihood of radiological health effects occurring due to such an exposure. Upon exposure to naturally occurring background gamma radiation, DU particles in the body will produce an enhancement of the dose to the tissue in the immediate vicinity of the particles due to the photo-electric absorption of the radiation in the particle. In this study, the photo-electrons produced by a 10 μm-size particle embedded in tissue at the centre of the human torso have been investigated. The mean energies of the photo-electrons in the DU particle and in the two consecutive immediately surrounding 2 μm-wide tissue shells around the particle were found to be 38, 49 and 50 keV, respectively, with corresponding ranges of 1.3, 38 and 39 μm, respectively. The total photo-electron fluence-rates in the two consecutive 2 μm-wide tissue layers were found to be 14% and 7% of the fluence-rate in the DU particle, respectively. The estimated dose enhancement due to one 10 μm-sized DU particle in 1 cm(3) of tissue was less than 2 in 10 million of the dose received by the tissue without a particle being present. The increase in risk of death from cancer due to this effect is consequently insignificant.

  6. Transcatheter pledget-assisted suture tricuspid annuloplasty (PASTA) to create a double-orifice valve.

    PubMed

    Khan, Jaffar M; Rogers, Toby; Schenke, William H; Greenbaum, Adam B; Babaliaros, Vasilis C; Paone, Gaetano; Ramasawmy, Rajiv; Chen, Marcus Y; Herzka, Daniel A; Lederman, Robert J

    2018-02-06

    Pledget-assisted suture tricuspid valve annuloplasty (PASTA) is a novel technique using marketed equipment to deliver percutaneous trans-annular sutures to create a double-orifice tricuspid valve. Tricuspid regurgitation is a malignant disease with high surgical mortality and no commercially available transcatheter solution in the US. Two iterations of PASTA were tested using trans-apical or trans-jugular access in swine. Catheters directed paired coronary guidewires to septal and lateral targets on the tricuspid annulus under fluoroscopic and echocardiographic guidance. Guidewires were electrified to traverse the annular targets and exchanged for pledgeted sutures. The sutures were drawn together and knotted, apposing septal and lateral targets, creating a double orifice tricuspid valve. Twenty-two pigs underwent PASTA. Annular and chamber dimensions were reduced (annular area, 10.1 ± 0.8 cm 2 to 3.8 ± 1.5 cm 2 (naïve) and 13.1 ± 1.5 cm 2 to 6.2 ± 1.0 cm 2 (diseased); septal-lateral diameter, 3.9 ± 0.3 mm to 1.4 ± 0.6 mm (naïve) and 4.4 ± 0.4 mm to 1.7 ± 1.0 mm (diseased); and right ventricular end-diastolic volume, 94 ± 13 ml to 85 ± 14 ml (naïve) and 157 ± 25 ml to 143 ± 20 ml (diseased)). MRI derived tricuspid regurgitation fraction fell from 32 ± 12% to 4 ± 5%. Results were sustained at 30 days. Pledget pull-through force was five-fold higher (40.6 ± 11.7N vs 8.0 ± 2.6N, P < .01) using this strategy compared to single puncture techniques used to anchor current investigational devices. Serious complications were related to apical access. PASTA reduces annular dimensions and tricuspid regurgitation in pigs. It may be cautiously applied to selected patients with severe tricuspid regurgitation and no options. This is the first transcatheter procedure, to our knowledge, to deliver standard pledgeted sutures to repair cardiac pathology. Published 2018. This article is a U

  7. Teachers' Knowledge and Views on the Use of Learners' Socio-Cultural Background in Teaching Natural Sciences in Grade 9 Township Classes

    ERIC Educational Resources Information Center

    Mavuru, Lydia; Ramnarain, Umesh

    2017-01-01

    This article explores teachers' knowledge and views on the role of learners' socio-cultural background when teaching Natural Sciences to Grade 9 learners at three South African township schools. Within a socio-cultural framework, the research investigated how teachers accommodate learners' cultural norms and values, religion and beliefs,…

  8. Manufacturer-provided effective orifice area index charts and the prevention of prosthesis-patient mismatch.

    PubMed

    House, Chad M; Nelson, William B; Kroshus, Timothy J; Dahiya, Ranjan; Pibarot, Philippe

    2012-01-01

    Prosthesis-patient mismatch (PPM) occurs when an implanted prosthesis is too small relative to the patient's body surface area (BSA). However, mismatch can often be prevented by indexing the expected effective orifice area (EOA) of a prosthesis to the patient's BSA and then selecting the largest implantable prosthesis to avoid mismatch. Previously, prosthesis manufacturers have attempted to simplify this process by providing charts that include the expected EOA for their prosthesis, already indexed into an array of BSA values. One caveat with these charts is that the expected EOA data must truly be reliable, or the charts will misguide the implanting surgeon. Manufacturer-provided charts could be improved by standardizing the EOA data, with one potential source being the hemodynamic data submitted to the United States Food and Drug Administration. This review discusses PPM, manufacturer-provided EOA charts, and the regulation of EOA data.

  9. Geostatistics as a tool to improve the natural background level definition: An application in groundwater.

    PubMed

    Dalla Libera, Nico; Fabbri, Paolo; Mason, Leonardo; Piccinini, Leonardo; Pola, Marco

    2017-11-15

    The Natural Background Level (NBL), suggested by UE BRIDGE project, is suited for spatially distributed datasets providing a regional value that could be higher than the Threshold Value (TV) set by every country. In hydro-geochemically dis-homogeneous areas, the use of a unique regional NBL, higher than TV, could arise problems to distinguish between natural occurrences and anthropogenic contaminant sources. Hence, the goal of this study is to improve the NBL definition employing a geostatistical approach, which reconstructs the contaminant spatial structure accounting geochemical and hydrogeological relationships. This integrated mapping is fundamental to evaluate the contaminant's distribution impact on the NBL, giving indications to improve it. We decided to test this method on the Drainage Basin of Venice Lagoon (DBVL, NE Italy), where the existing NBL is seven times higher than the TV. This area is notoriously affected by naturally occurring arsenic contamination. An available geochemical dataset collected by 50 piezometers was used to reconstruct the spatial distribution of arsenic in the densely populated area of the DBVL. A cokriging approach was applied exploiting the geochemical relationships among As, Fe and NH4+. The obtained spatial predictions of arsenic concentrations were divided into three different zones: i) areas with an As concentration lower than the TV, ii) areas with an As concentration between the TV and the median of the values higher than the TV, and iii) areas with an As concentration higher than the median. Following the BRIDGE suggestions, where enough samples were available, the 90th percentile for each zone was calculated to obtain a local NBL (LNBL). Differently from the original NBL, this local value gives more detailed water quality information accounting the hydrogeological and geochemical setting, and contaminant spatial variation. Hence, the LNBL could give more indications about the distinction between natural occurrence and

  10. SU-F-T-166: On the Nature of the Background Visible Light Observed in Fiber Optic Dosimetry of Proton Beams

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Darafsheh, A; Kassaee, A; Finlay, J

    Purpose: The nature of the background visible light observed during fiber optic dosimetry of proton beams, whether it is due to Cherenkov radiation or not, has been debated in the literature recently. In this work, experimentally and by means of Monte Carlo simulations, we shed light on this problem and investigated the nature of the background visible light observed in fiber optics irradiated with proton beams. Methods: A bare silica fiber optics was embedded in tissue-mimicking phantoms and irradiated with clinical proton beams with energies of 100–225 MeV at Roberts Proton Therapy Center. Luminescence spectroscopy was performed by a CCD-coupledmore » spectrograph to analyze in detail the emission spectrum of the fiber tip across the visible range of 400–700 nm. Monte Carlo simulation was performed by using FLUKA Monte Carlo code to simulate Cherenkov light and ionizing radiation dose deposition in the fiber. Results: The experimental spectra of the irradiated silica fiber shows two distinct peaks at 450 and 650 nm, whose spectral shape is different from that of Cherenkov radiation. We believe that the nature of these peaks are connected to the point defects of silica including oxygen-deficiency center (ODC) and non-bridging oxygen hole center (NBOHC). Monte Carlo simulations confirmed the experimental observations that Cherenkov radiation cannot be solely responsible for such a signal. Conclusion: We showed that Cherenkov radiation is not the dominant visible signal observed in bare fiber optics irradiated with proton beams. We observed two distinct peaks at 450 and 650 nm whose nature is connected with the point defects of silica fiber including oxygen-deficiency center and non-bridging oxygen hole center.« less

  11. Triple-orifice valve repair in severe Barlow disease with multiple-jet mitral regurgitation: report of mid-term experience.

    PubMed

    Fucci, Carlo; Faggiano, Pompilio; Nardi, Matilde; D'Aloia, Antonio; Coletti, Giuseppe; De Cicco, Giuseppe; Latini, Leonardo; Vizzardi, Enrico; Lorusso, Roberto

    2013-09-10

    Barlow disease represents a surgical challenge for mitral valve repair (MR) in the presence of mitral insufficiency (MI) with multiple regurgitant jets. We hereby present our mid-term experience using a modified edge-to-edge technique to address this peculiar MI. From March 2003 till December 2010, 25 consecutive patients (mean age 54 ± 7 years, 14 males) affected by severe Barlow disease with multiple regurgitant jets were submitted to MR. Preoperative transesophageal echo (TEE) in all the cases showed at least 2 regurgitant jets, involving one or both leaflets in more than one segment. In all the patients, a triple orifice valve (TOV) repair with annuloplasty was performed. Intra-operative TEE and postoperative transthoracic echocardiography (TTE) were carried out to evaluate results of the TOV repair. There was no in-hospital death and one late death (non-cardiac related). At intra-operative TEE, the three orifices showed a mean total valve area of 2.9 ± 0.1cm(2) (range 2.5-3.3 cm(2)) with no residual regurgitation (2 cases of trivial MI) and no sign of valve stenosis (mean transvalvular gradient 4.6 ± 1.5 mmHg). At follow up (mean 38 ± 22 months), TTE showed favourable MR and no recurrence of significant MI (6 cases of trivial and 1 of mild MI). Stress TTE was performed in 5 cases showing persistent effective valve function (2 cases of trivial MI at peak exercise). All the patients showed significant NYHA functional class improvement. This report indicates that the TOV technique is effective in correcting complex Barlow mitral valves with multiple jets. Further studies are required to confirm long-term applicability and durability in more numerous clinical cases. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  12. Educational Background, Teaching Experience and Teachers' Views on the Inclusion of Nature of Science in the Science Curriculum

    NASA Astrophysics Data System (ADS)

    Martín-Díaz, M. J.

    2006-08-01

    The aim of this research is to ascertain teachers’ opinions on what elements of nature of science (NOS) and science technology society relationships (STS) should be taught in school science. To this end an adapted version of the questionnaire developed by Osborne et al. is used. Our results show that experts consulted by Osborne et al. and Spanish teachers confer similar importance on the provisional, experimental, and predictive nature of scientific knowledge based on some of the procedures used such as the drawing up of hypotheses and the analysis and interpretation of data. We also look into the relationship between the teachers’ views and their educational background.1 Results suggest that philosophy teachers are more concerned with the inclusion of NOS and STS topics in science curricula than science teachers, although further studies will be necessary. Some suggestions concerning the university training of science teachers are also discussed.

  13. Hydrogeochemical characterization and Natural Background Levels in urbanized areas: Milan Metropolitan area (Northern Italy)

    NASA Astrophysics Data System (ADS)

    De Caro, Mattia; Crosta, Giovanni B.; Frattini, Paolo

    2017-04-01

    Although aquifers in densely populated and industrialized areas are extremely valuable and sensitive to contamination, an estimate of the groundwater quality status relative to baseline conditions is lacking for many of them. This paper provides a hydrogeochemical characterization of the groundwater in the Milan metropolitan area, one of the most densely populated areas in Europe. First, a conceptual model of the study area based on the analysis of the spatial distribution of natural chemical species and indicator contaminants is presented. The hydrochemical facies of the study area depend on the lithology of catchments drained by the main contributing rivers and on the aquifer settings. The anthropogenic influence on the groundwater quality of superficial aquifers is studied by means of probability plots, concentration versus depth plots and spatial-temporal plots for nitrate, sulfate and chloride. These allow differentiation of contaminated superficial aquifers from deep confined aquifers with baseline water quality. Natural Background Levels (NBL) of selected species (Cl, Na, NH4, SO4, NO3, As, Fe, Mn and Zn) are estimated by means of the pre-selection (PS) and the component separation (CS) statistical approaches. The NBLs depend on hydrogeological settings of the study area; sodium, chloride, sulfate and zinc NBL values never exceed the environmental water quality standards. NBL values of ammonium, iron, arsenic and manganese exceed the environmental water quality standards in the anaerobic portion of the aquifers. On the basis of observations, a set of criteria and precautions are suggested for adoption with both PS and CS methods in the aquifer characterization of highly urbanized areas.

  14. Statistical Modeling of Natural Backgrounds in Hyperspectral LWIR Data

    DTIC Science & Technology

    2016-09-06

    extremely important for studying performance trades. First, we study the validity of this model using real hyperspectral data, and compare the relative...difficult to validate any statistical model created for a target of interest. However, since background measurements are plentiful, it is reasonable to...Golden, S., Less, D., Jin, X., and Rynes, P., “ Modeling and analysis of LWIR signature variability associated with 3d and BRDF effects,” 98400P (May 2016

  15. Cumulative neutrino background from quasar-driven outflows

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wang, Xiawei; Loeb, Abraham, E-mail: xiawei.wang@cfa.harvard.edu, E-mail: aloeb@cfa.harvard.edu

    2016-12-01

    Quasar-driven outflows naturally account for the missing component of the extragalactic γ-ray background through neutral pion production in interactions between protons accelerated by the forward outflow shock and interstellar protons. We study the simultaneous neutrino emission by the same protons. We adopt outflow parameters that best fit the extragalactic γ-ray background data and derive a cumulative neutrino background of ∼ 10{sup −7} GeV cm{sup −2} s{sup −1} sr{sup −1} at neutrino energies E {sub ν} ∼> 10 TeV, which naturally explains the most recent IceCube data without tuning any free parameters. The link between the γ-ray and neutrino emission frommore » quasar outflows can be used to constrain the high-energy physics of strong shocks at cosmological distances.« less

  16. Noncircular orifice holes and advanced fabrication techniques for liquid rocket injectors. Phase 3: Analytical and cold-flow experimental evaluation of rectangular concentric tube injector elements for gas/liquid application. Phase 4: Analytical and experimental evaluation of noncircular injector elements for gas/liquid and liquid/liquid application

    NASA Technical Reports Server (NTRS)

    Mchale, R. M.

    1974-01-01

    Results are presented of a cold-flow and hot-fire experimental study of the mixing and atomization characteristics of injector elements incorporating noncircular orifices. Both liquid/liquid and gas/liquid element types are discussed. Unlike doublet and triplet elements (circular orifices only) were investigated for the liquid/liquid case while concentric tube elements were investigated for the gas/liquid case. It is concluded that noncircular shape can be employed to significant advantage in injector design for liquid rocket engines.

  17. Effects of reduced natural background radiation on Drosophila melanogaster growth and development as revealed by the FLYINGLOW program.

    PubMed

    Morciano, Patrizia; Iorio, Roberto; Iovino, Daniela; Cipressa, Francesca; Esposito, Giuseppe; Porrazzo, Antonella; Satta, Luigi; Alesse, Edoardo; Tabocchini, Maria Antonella; Cenci, Giovanni

    2018-01-01

    Natural background radiation of Earth and cosmic rays played a relevant role during the evolution of living organisms. However, how chronic low doses of radiation can affect biological processes is still unclear. Previous data have indicated that cells grown at the Gran Sasso Underground Laboratory (LNGS, L'Aquila) of National Institute of Nuclear Physics (INFN) of Italy, where the dose rate of cosmic rays and neutrons is significantly reduced with respect to the external environment, elicited an impaired response against endogenous damage as compared to cells grown outside LNGS. This suggests that environmental radiation contributes to the development of defense mechanisms at cellular level. To further understand how environmental radiation affects metabolism of living organisms, we have recently launched the FLYINGLOW program that aims at exploiting Drosophila melanogaster as a model for evaluating the effects of low doses/dose rates of radiation at the organismal level. Here, we will present a comparative data set on lifespan, motility and fertility from different Drosophila strains grown in parallel at LNGS and in a reference laboratory at the University of L'Aquila. Our data suggest the reduced radiation environment can influence Drosophila development and, depending on the genetic background, may affect viability for several generations even when flies are moved back to normal background radiation. As flies are considered a valuable model for human biology, our results might shed some light on understanding the effect of low dose radiation also in humans. © 2017 Wiley Periodicals, Inc.

  18. Why background colour matters to bees and flowers.

    PubMed

    Bukovac, Zoë; Shrestha, Mani; Garcia, Jair E; Burd, Martin; Dorin, Alan; Dyer, Adrian G

    2017-05-01

    Flowers are often viewed by bee pollinators against a variety of different backgrounds. On the Australian continent, backgrounds are very diverse and include surface examples of all major geological stages of the Earth's history, which have been present during the entire evolutionary period of Angiosperms. Flower signals in Australia are also representative of typical worldwide evolutionary spectral adaptations that enable successful pollination. We measured the spectral properties of 581 natural surfaces, including rocks, sand, green leaves, and dry plant materials, sampled from tropical Cairns through to the southern tip of mainland Australia. We modelled in a hexagon colour space, how interactions between background spectra and flower-like colour stimuli affect reliable discrimination and detection in bee pollinators. We calculated the extent to which a given locus would be conflated with the loci of a different flower-colour stimulus using empirically determined colour discrimination regions for bee vision. Our results reveal that whilst colour signals are robust in homogeneous background viewing conditions, there could be significant pressure on plant flowers to evolve saliently-different colours to overcome background spectral noise. We thus show that perceptual noise has a large influence on how colour information can be used in natural conditions.

  19. Prediction of Bubble Diameter at Detachment from a Wall Orifice in Liquid Cross Flow Under Reduced and Normal Gravity Conditions

    NASA Technical Reports Server (NTRS)

    Nahra, Henry K.; Kamotani, Y.

    2003-01-01

    Bubble formation and detachment is an integral part of the two-phase flow science. The objective of the present work is to theoretically investigate the effects of liquid cross-flow velocity, gas flow rate embodied in the momentum flux force, and orifice diameter on bubble formation in a wall-bubble injection configuration. A two-dimensional one-stage theoretical model based on a global force balance on the bubble evolving from a wall orifice in a cross liquid flow is presented in this work. In this model, relevant forces acting on the evolving bubble are expressed in terms of the bubble center of mass coordinates and solved simultaneously. Relevant forces in low gravity included the momentum flux, shear-lift, surface tension, drag and inertia forces. Under normal gravity conditions, the buoyancy force, which is dominant under such conditions, can be added to the force balance. Two detachment criteria were applicable depending on the gas to liquid momentum force ratio. For low ratios, the time when the bubble acceleration in the direction of the detachment angle is greater or equal to zero is calculated from the bubble x and y coordinates. This time is taken as the time at which all the detaching forces that are acting on the bubble are greater or equal to the attaching forces. For high gas to liquid momentum force ratios, the time at which the y coordinate less the bubble radius equals zero is calculated. The bubble diameter is evaluated at this time as the diameter at detachment from the fact that the bubble volume is simply given by the product of the gas flow rate and time elapsed. Comparison of the model s predictions was also made with predictions from a two-dimensional normal gravity model based on Kumar-Kuloor formulation and such a comparison is presented in this work.

  20. Human exposure to high natural background radiation: what can it teach us about radiation risks?

    PubMed Central

    Hendry, Jolyon H; Simon, Steven L; Wojcik, Andrzej; Sohrabi, Mehdi; Burkart, Werner; Cardis, Elisabeth; Laurier, Dominique; Tirmarche, Margot; Hayata, Isamu

    2014-01-01

    Natural radiation is the major source of human exposure to ionising radiation, and its largest contributing component to effective dose arises from inhalation of 222Rn and its radioactive progeny. However, despite extensive knowledge of radiation risks gained through epidemiologic investigations and mechanistic considerations, the health effects of chronic low-level radiation exposure are still poorly understood. The present paper reviews the possible contribution of studies of populations living in high natural background radiation (HNBR) areas (Guarapari, Brazil; Kerala, India; Ramsar, Iran; Yangjiang, China), including radon-prone areas, to low dose risk estimation. Much of the direct information about risk related to HNBR comes from case–control studies of radon and lung cancer, which provide convincing evidence of an association between long-term protracted radiation exposures in the general population and disease incidence. The success of these studies is mainly due to the careful organ dose reconstruction (with relatively high doses to the lung), and to the fact that large-scale collaborative studies have been conducted to maximise the statistical power and to ensure the systematic collection of information on potential confounding factors. In contrast, studies in other (non-radon) HNBR areas have provided little information, relying mainly on ecological designs and very rough effective dose categorisations. Recent steps taken in China and India to establish cohorts for follow-up and to conduct nested case–control studies may provide useful information about risks in the future, provided that careful organ dose reconstruction is possible and information is collected on potential confounding factors. PMID:19454802

  1. Top-down preparation modulates visual categorization but not subjective awareness of objects presented in natural backgrounds.

    PubMed

    Koivisto, Mika; Kahila, Ella

    2017-04-01

    Top-down processes are widely assumed to be essential in visual awareness, subjective experience of seeing. However, previous studies have not tried to separate directly the roles of different types of top-down influences in visual awareness. We studied the effects of top-down preparation and object substitution masking (OSM) on visual awareness during categorization of objects presented in natural scene backgrounds. The results showed that preparation facilitated categorization but did not influence visual awareness. OSM reduced visual awareness and impaired categorization. The dissociations between the effects of preparation and OSM on visual awareness and on categorization imply that they influence at different stages of cognitive processing. We propose that preparation influences at the top of the visual hierarchy, whereas OSM interferes with processes occurring at lower levels of the hierarchy. These lower level processes play an essential role in visual awareness. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. International Conference on Natural Orifice Transluminal Endoscopic Surgery (NOTES)

    DTIC Science & Technology

    2006-06-01

    causing evisceration. At exploration, a pancreatic stump leak also was noted. Drains were placed, and the patient was placed on total parenteral nutrition ...Department of Surgery. St. Joseph Clinic. Liege, Belgium Hospital Dr. Peset Aleixandre. Valencia. Spain 4 Clinica de Merida. Merida. Yucatan ...pneumonitis (n = 3), and parenteral nutrition (n = 1). There was conversion to laparotomy for 28 patients (2.7%), and surgical time ranged from 32 to 132

  3. Cholecystectomy: from Langenbuch to natural orifice transluminal endoscopic surgery.

    PubMed

    Soper, Nathaniel J

    2011-07-01

    Gallstones have led to pain and complications in humankind for millennia. Beginning in the 1880s, cholecystectomy, performed through a sizable abdominal incision, was the treatment of choice for symptomatic cholelithiasis. During the late 1980s pioneering surgeons first used laparoscopic techniques to remove the gallbladder. Although initially associated with a significantly increased rate of bile duct injury, the clinical advantages of laparoscopy compared to open operation became readily apparent, ushering in the "laparoscopic revolution." More recently, attempts at rendering cholecystectomy even less invasive--smaller or fewer incisions or eliminating abdominal incisions altogether--have been described, with limited clinical series reported. At the current time, laparoscopic cholecystectomy is the gold standard for gallbladder removal, and any newer techniques must be demonstrated to result in superior outcomes for widespread adoption.

  4. Evaluation of background radiation dose contributions in the United Arab Emirates.

    PubMed

    Goddard, Braden; Bosc, Emmanuel; Al Hasani, Sarra; Lloyd, Cody

    2018-09-01

    The natural background radiation consists of three main components; cosmic, terrestrial, and skyshine. Although there are currently methods available to measure the total dose rate from background radiation, no established methods exist that allow for the measurement of each component the background radiation. This analysis consists of a unique methodology in which the dose rate contribution from each component of the natural background radiation is measured and calculated. This project evaluates the natural background dose rate in the Abu Dhabi City region from all three of these components using the developed methodology. Evaluating and understanding the different components of background radiation provides a baseline allowing for the detection, and possibly attribution, of elevated radiation levels. Measurements using a high-pressure ion chamber with different shielding configurations and two offshore measurements provided dose rate information that were attributed to the different components of the background radiation. Additional spectral information was obtained using an HPGe detector to verify and quantify the presence of terrestrial radionuclides. By evaluating the dose rates of the different shielding configurations the comic, terrestrial, and skyshine contribution in the Abu Dhabi City region were determined to be 33.0 ± 1.7, 15.7 ± 2.5, and 2.4 ± 2.1 nSv/h, respectively. Copyright © 2018. Published by Elsevier Ltd.

  5. Enhancement of natural background gamma-radiation dose around uranium microparticles in the human body.

    PubMed

    Pattison, John E; Hugtenburg, Richard P; Green, Stuart

    2010-04-06

    Ongoing controversy surrounds the adverse health effects of the use of depleted uranium (DU) munitions. The biological effects of gamma-radiation arise from the direct or indirect interaction between secondary electrons and the DNA of living cells. The probability of the absorption of X-rays and gamma-rays with energies below about 200 keV by particles of high atomic number is proportional to the third to fourth power of the atomic number. In such a case, the more heavily ionizing low-energy recoil electrons are preferentially produced; these cause dose enhancement in the immediate vicinity of the particles. It has been claimed that upon exposure to naturally occurring background gamma-radiation, particles of DU in the human body would produce dose enhancement by a factor of 500-1000, thereby contributing a significant radiation dose in addition to the dose received from the inherent radioactivity of the DU. In this study, we used the Monte Carlo code EGSnrc to accurately estimate the likely maximum dose enhancement arising from the presence of micrometre-sized uranium particles in the body. We found that although the dose enhancement is significant, of the order of 1-10, it is considerably smaller than that suggested previously.

  6. Enhancement of natural background gamma-radiation dose around uranium microparticles in the human body

    PubMed Central

    Pattison, John E.; Hugtenburg, Richard P.; Green, Stuart

    2010-01-01

    Ongoing controversy surrounds the adverse health effects of the use of depleted uranium (DU) munitions. The biological effects of gamma-radiation arise from the direct or indirect interaction between secondary electrons and the DNA of living cells. The probability of the absorption of X-rays and gamma-rays with energies below about 200 keV by particles of high atomic number is proportional to the third to fourth power of the atomic number. In such a case, the more heavily ionizing low-energy recoil electrons are preferentially produced; these cause dose enhancement in the immediate vicinity of the particles. It has been claimed that upon exposure to naturally occurring background gamma-radiation, particles of DU in the human body would produce dose enhancement by a factor of 500–1000, thereby contributing a significant radiation dose in addition to the dose received from the inherent radioactivity of the DU. In this study, we used the Monte Carlo code EGSnrc to accurately estimate the likely maximum dose enhancement arising from the presence of micrometre-sized uranium particles in the body. We found that although the dose enhancement is significant, of the order of 1–10, it is considerably smaller than that suggested previously. PMID:19776147

  7. Skyshine Contribution to Gamma Ray Background Between 0 and 4 MeV

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mitchell, Allison L.; Borgardt, James D.; Kouzes, Richard T.

    2009-08-14

    Natural gamma-ray background is composed of four components; which include cosmic rays, cosmic ray produced atmospheric activity, terrestrial sources, and skyshine from terrestrial sources. Skyshine is radiation scattered from the air above a source that can produce a signal in radiation detection instrumentation. Skyshine has been studied for many years but its contribution to the natural background observed in a detector has not been studied. A large NaI(Tl) detector was used to investigate each of the four components of the natural background using a series of 48-hour measurements and appropriate lead shielding configured to discriminate contributions from each component. Itmore » was found that while the contribution from skyshine decreases rapidly with energy, it represents a significant portion of the background spectrum below ~500keV. A similar campaign of measurements using a HPGe detector is underway.« less

  8. Characterizing the Background Corona with SDO/AIA

    NASA Technical Reports Server (NTRS)

    Napier, Kate; Alexander, Caroline; Winebarger, Amy

    2014-01-01

    Characterizing the nature of the solar coronal background would enable scientists to more accurately determine plasma parameters, and may lead to a better understanding of the coronal heating problem. Because scientists study the 3D structure of the Sun in 2D, any line-of-sight includes both foreground and background material, and thus, the issue of background subtraction arises. By investigating the intensity values in and around an active region, using multiple wavelengths collected from the Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory (SDO) over an eight-hour period, this project aims to characterize the background as smooth or structured. Different methods were employed to measure the true coronal background and create minimum intensity images. These were then investigated for the presence of structure. The background images created were found to contain long-lived structures, including coronal loops, that were still present in all of the wavelengths, 131, 171, 193, 211, and 335 A. The intensity profiles across the active region indicate that the background is much more structured than previously thought.

  9. Stimulus background influences phase invariant coding by correlated neural activity

    PubMed Central

    Metzen, Michael G; Chacron, Maurice J

    2017-01-01

    Previously we reported that correlations between the activities of peripheral afferents mediate a phase invariant representation of natural communication stimuli that is refined across successive processing stages thereby leading to perception and behavior in the weakly electric fish Apteronotus leptorhynchus (Metzen et al., 2016). Here, we explore how phase invariant coding and perception of natural communication stimuli are affected by changes in the sinusoidal background over which they occur. We found that increasing background frequency led to phase locking, which decreased both detectability and phase invariant coding. Correlated afferent activity was a much better predictor of behavior as assessed from both invariance and detectability than single neuron activity. Thus, our results provide not only further evidence that correlated activity likely determines perception of natural communication signals, but also a novel explanation as to why these preferentially occur on top of low frequency as well as low-intensity sinusoidal backgrounds. DOI: http://dx.doi.org/10.7554/eLife.24482.001 PMID:28315519

  10. 'Natural background' soil water repellency in conifer forests of the north-western USA: Its prediction and relationship to wildfire occurrence

    USGS Publications Warehouse

    Doerr, S.H.; Woods, S.W.; Martin, D.A.; Casimiro, M.

    2009-01-01

    Soils under a wide range of vegetation types exhibit water repellency following the passage of a fire. This is viewed by many as one of the main causes for accelerated post-fire runoff and soil erosion and it has often been assumed that strong soil water repellency present after wildfire is fire-induced. However, high levels of repellency have also been reported under vegetation types not affected by fire, and the question arises to what degree the water repellency observed at burnt sites actually results from fire. This study aimed at determining 'natural background' water repellency in common coniferous forest types in the north-western USA. Mature or semi-mature coniferous forest sites (n = 81), which showed no evidence of recent fires and had at least some needle cast cover, were sampled across six states. After careful removal of litter and duff at each site, soil water repellency was examined in situ at the mineral soil surface using the Water Drop Penetration Time (WDPT) method for three sub-sites, followed by collecting near-surface mineral soil layer samples (0-3 cm depth). Following air-drying, samples were further analyzed for repellency using WDPT and contact angle (??sl) measurements. Amongst other variables examined were dominant tree type, ground vegetation, litter and duff layer depth, slope angle and aspect, elevation, geology, and soil texture, organic carbon content and pH. 'Natural background' water repellency (WDPT > 5 s) was detected in situ and on air-dry samples at 75% of all sites examined irrespective of dominant tree species (Pinus ponderosa, Pinus contorta, Picea engelmanii and Pseudotsuga menziesii). These findings demonstrate that the soil water repellency commonly observed in these forest types following burning is not necessarily the result of recent fire but can instead be a natural characteristic. The notion of a low background water repellency being typical for long-unburnt conifer forest soils of the north-western USA is

  11. Illuminating the Background: Topics in Cosmic Microwave Background Polarization Research

    NASA Astrophysics Data System (ADS)

    Miller, Nathan J.

    The cosmic microwave background provides a wealth of information about the origin and history of the universe. The statistics of the anisotropy and the polarization of the cosmic microwave background, among other things, can tell us about the distribution of matter, the redshift of reionization, and the nature of the primordial uctuations. From the lensing of cosmic microwave background due to intervening matter, we can extract information about neutrinos and the equation of state of dark energy. A measurement of the large angular scale B-mode polarization has been called the "smoking gun" of in ation, a theory that describes a possible early rapid expansion of the universe. The focus of current experiments is to measure this B-mode polarization, while several experiments, such as POLARBEAR, are also looking to measure the lensing of the cosmic microwave background. This dissertation will discuss several different topics in cosmic microwave background polarization research. I will make predictions for future experiments and I will also show analysis for two current experiments, POLARBEAR and BICEP. I will show how beam systematics affect the measurement of cosmological parameters and how well we must limit these systematics in order to get unbiased constraints on cosmological parameters for future experiments. I will discuss a novel way of using the temperature-polarization cross correlation to constrain the amount of inflationary gravitational waves. Through Markov Chain Monte Carlo methods, I will determine how well future experiments will be able to constrain the neutrino masses and their degeneracy parameters. I will show results from current data analysis and calibration being done on the Cedar Flat deployment for the POLARBEAR experiment which is currently being constructed in the Atacama desert in Chile. Finally, I will analyze the claim of detection of cosmological birefringence in the BICEP data and show that there is reason to believe it is due to

  12. Background radiation measurements at high power research reactors

    NASA Astrophysics Data System (ADS)

    Ashenfelter, J.; Balantekin, B.; Baldenegro, C. X.; Band, H. R.; Barclay, G.; Bass, C. D.; Berish, D.; Bowden, N. S.; Bryan, C. D.; Cherwinka, J. J.; Chu, R.; Classen, T.; Davee, D.; Dean, D.; Deichert, G.; Dolinski, M. J.; Dolph, J.; Dwyer, D. A.; Fan, S.; Gaison, J. K.; Galindo-Uribarri, A.; Gilje, K.; Glenn, A.; Green, M.; Han, K.; Hans, S.; Heeger, K. M.; Heffron, B.; Jaffe, D. E.; Kettell, S.; Langford, T. J.; Littlejohn, B. R.; Martinez, D.; McKeown, R. D.; Morrell, S.; Mueller, P. E.; Mumm, H. P.; Napolitano, J.; Norcini, D.; Pushin, D.; Romero, E.; Rosero, R.; Saldana, L.; Seilhan, B. S.; Sharma, R.; Stemen, N. T.; Surukuchi, P. T.; Thompson, S. J.; Varner, R. L.; Wang, W.; Watson, S. M.; White, B.; White, C.; Wilhelmi, J.; Williams, C.; Wise, T.; Yao, H.; Yeh, M.; Yen, Y.-R.; Zhang, C.; Zhang, X.; Prospect Collaboration

    2016-01-01

    Research reactors host a wide range of activities that make use of the intense neutron fluxes generated at these facilities. Recent interest in performing measurements with relatively low event rates, e.g. reactor antineutrino detection, at these facilities necessitates a detailed understanding of background radiation fields. Both reactor-correlated and naturally occurring background sources are potentially important, even at levels well below those of importance for typical activities. Here we describe a comprehensive series of background assessments at three high-power research reactors, including γ-ray, neutron, and muon measurements. For each facility we describe the characteristics and identify the sources of the background fields encountered. The general understanding gained of background production mechanisms and their relationship to facility features will prove valuable for the planning of any sensitive measurement conducted therein.

  13. Contributions of Various Radiological Sources to Background in a Suburban Environment

    DOE PAGES

    Milvenan, Richard D.; Hayes, Robert B.

    2016-11-01

    This work is a brief overview and comparison of dose rates stemming from both indoor and outdoor natural background radiation and household objects within a suburban environment in North Carolina. Combined gamma and beta dose rates were taken from indoor objects that ranged from the potassium in fruit to the americium in smoke detectors. For outdoor measurements, various height and time data samples were collected to show fluctuations in dose rate due to temperature inversion and geometric attenuation. Although each sample tested proved to have a statistically significant increase over background using Students t-test, no sample proved to be moremore » than a minor increase in natural radiation dose. Furthermore, the relative contributions from natural radioactivity such as potassium in foods and common household items are shown to be easily distinguished from background using standard handheld instrumentation when applied in a systematic, methodological manner.« less

  14. Contributions of Various Radiological Sources to Background in a Suburban Environment

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Milvenan, Richard D.; Hayes, Robert B.

    This work is a brief overview and comparison of dose rates stemming from both indoor and outdoor natural background radiation and household objects within a suburban environment in North Carolina. Combined gamma and beta dose rates were taken from indoor objects that ranged from the potassium in fruit to the americium in smoke detectors. For outdoor measurements, various height and time data samples were collected to show fluctuations in dose rate due to temperature inversion and geometric attenuation. Although each sample tested proved to have a statistically significant increase over background using Students t-test, no sample proved to be moremore » than a minor increase in natural radiation dose. Furthermore, the relative contributions from natural radioactivity such as potassium in foods and common household items are shown to be easily distinguished from background using standard handheld instrumentation when applied in a systematic, methodological manner.« less

  15. Shielding concepts for low-background proportional counter arrays in surface laboratories

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Aalseth, Craig E.; Humble, Paul H.; Mace, Emily K.

    2016-02-01

    Development of ultra low background gas proportional counters has made the contribution from naturally occurring radioactive isotopes – primarily and activity in the uranium and thorium decay chains – inconsequential to instrumental sensitivity levels when measurements are performed in above ground surface laboratories. Simple lead shielding is enough to mitigate against gamma rays as gas proportional counters are already relatively insensitive to naturally occurring gamma radiation. The dominant background in these surface laboratory measurements using ultra low background gas proportional counters is due to cosmic ray generated muons, neutrons, and protons. Studies of measurements with ultra low background gas proportionalmore » counters in surface and underground laboratories as well as radiation transport Monte Carlo simulations suggest a preferred conceptual design to achieve the highest possible sensitivity from an array of low background gas proportional counters when operated in a surface laboratory. The basis for a low background gas proportional counter array and the preferred shielding configuration is reported, especially in relation to measurements of radioactive gases having low energy decays such as 37Ar.« less

  16. Study of Background Rejection Systems for the IXO Mission.

    NASA Astrophysics Data System (ADS)

    Laurent, Philippe; Limousin, O.; Tatischeff, V.

    2009-01-01

    The scientific performances of the IXO mission will necessitate a very low detector background level. This will imply thorough background simulations, and efficient background rejection systems. It necessitates also a very good knowledge of the detectors to be shielded. In APC, Paris, and CEA, Saclay, we got experience on these activities by conceiving and optimising in parallel the high energy detector and the active and passive background rejection system of the Simbol-X mission. Considering that this work may be naturally extended to other X-ray missions, we have initiated with CNES a R&D project on the study of background rejection systems mainly in view the IXO project. We will detail this activity in the poster.

  17. The nature of the near-infrared interline sky background using fibre Bragg grating OH suppression

    NASA Astrophysics Data System (ADS)

    Trinh, Christopher Q.; Ellis, Simon C.; Bland-Hawthorn, Joss; Horton, Anthony J.; Lawrence, Jon S.; Leon-Saval, Sergio G.

    2013-07-01

    We analyse the near-infrared interline sky background, OH and O2 emission in 19 h of H-band observations with the GNOSIS OH-suppression unit and the IRIS2 spectrograph at the 3.9-m Anglo-Australian Telescope. We find that the long-term behaviour of OH emission is best described by a gradual decrease during the first half of the night followed by a gradual increase during the second half of the night following the behaviour of the solar elevation angle. We measure the interline background at 1.520 μm where the instrumental thermal background is very low and study its variation with zenith distance, time after sunset, ecliptic latitude, lunar zenith distance and lunar distance to determine the presence of non-thermal atmospheric emission, zodiacal scattered light and scattered moonlight. Zodiacal scattered light is too faint to be detected in the summed observations. Scattered moonlight due to Mie scattering by atmospheric aerosols is seen at small lunar distances (ρ ≲ 11°), but is otherwise too faint to detect. Except at very small lunar distances the interline background at a resolving power of R ≈ 2400 when using OH-suppression fibres is dominated by a non-thermal atmospheric source with a temporal behaviour that resembles atmospheric OH emission, suggesting that the interline background contains instrumentally scattered OH. However, the interline background dims more rapidly than OH early in the night, suggesting contributions from rapid dimming molecules. The absolute interline background is 560 ± 120 photons s-1 m-2 μm- 1 arcsec-2 under dark conditions. This value is similar to previous measurements without OH suppression, suggesting that non-suppressed atmospheric emission is responsible for the interline background level. Future OH-suppression fibre designs may address this by the suppression of more sky lines using more accurate sky-line measurements taken from high-resolution spectra.

  18. Radioprotective Effects of Sulfur-containing Mineral Water of Ramsar Hot Spring with High Natural Background Radiation on Mouse Bone Marrow Cells.

    PubMed

    Heidari, A H; Shabestani Monfared, A; Mozdarani, H; Mahmoudzadeh, A; Razzaghdoust, A

    2017-12-01

    We intend to study the inhibitory effect of sulfur compound in Ramsar hot spring mineral on tumor-genesis ability of high natural background radiation. The radioprotective effect of sulfur compounds was previously shown on radiation-induced chromosomal aberration, micronuclei in mouse bone marrow cells and human peripheral lymphocyte. Ramsar is known for having the highest level of natural background radiation on Earth. This study was performed to show the radioprotective effect of sulfur-containing Ramsar mineral water on mouse bone marrow cells. Mice were fed three types of water (drinking water, Ramsar radioactive water containing sulfur and Ramsar radioactive water whose sulfur was removed). Ten days after feeding, mice were irradiated by gamma rays (0, 2 and 4 Gy). 48 and 72 hours after irradiating, mice were killed and femurs were removed. Frequency of micronuclei was determined in bone marrow erythrocytes. A significant reduction was shown in the rate of micronuclei polychromatic erythrocyte in sulfur-containing hot spring water compared to sulfur-free water in hot spring mineral water. Gamma irradiation induced significant increases in micronuclei polychromatic erythrocyte (MNPCE) and decreases in polychromatic erythrocyte/polychromatic erythrocyte + normochromatic erythrocyte ratio (PCEs/PCEs+NCEs) (P < 0.001) in sulfur-containing hot spring water compared to sulfur-free hot spring mineral water. Also, apparently there was a significant difference between drinking water and sulfur-containing hot spring water in micronuclei polychromatic erythrocyte and polychromatic erythrocyte/polychromatic erythrocyte+ normochromatic erythrocyte ratio. The results indicate that sulfur-containing mineral water could result in a significant reduction in radiation-induced micronuclei representing the radioprotective effect of sulfur compounds.

  19. Catheter orifice configuration influences the effectiveness of continuous peripheral nerve blockade.

    PubMed

    Fredrickson, Michael J; Ball, Craig M; Dalgleish, Adam J

    2011-01-01

    We investigated perineural catheter threading distance and orifice configuration during continuous interscalene analgesia. One hundred fifty-three patients receiving an anterolateral interscalene catheter (catheter needle and nerve/plexus in a similar alignment) for elective shoulder surgery were randomized to 1 of 3 groups: following out-of-plane ultrasound confirmation of the needle tip immediately lateral to the C5/6 roots, a nonstimulating catheter was blindly advanced 0.5 cm (end-hole; n = 50), 2.5 cm (multiorifice; n = 50) or 5 cm (multiorifice; n = 53) beyond the needle tip. Ropivacaine 0.75% + lidocaine 1% (50:50) 20 mL was administered preoperatively via the catheter before surgery under general anesthesia. A ropivacaine 0.2% 2 mL/hr elastomeric infusion with mandatory 6 hourly (and on demand) 5-mL boluses was continued for more than 48 hrs with tramadol available as rescue. Patients were questioned in the recovery room, at 24 and 48 hrs for numerical rating pain score (0-10), ropivacaine bolus, and tramadol consumption. Patients were more frequently pain-free in the recovery room in the multiorifice 2.5 and 5 cm groups compared with the end-hole 0.5 cm group (94%, 91% vs 66%; P < 0.001). During the first 24 hrs, the end-hole group demonstrated an earlier time to first pain (median, 10 vs17, 15 hrs; P < 0.001), higher "average pain" (median, 3 vs 1, 2, P = 0.004), and more ropivacaine bolus (median, 5 vs 3, 3; P < 0.001) and tramadol consumption (P = 0.01). Groups 2.5 and 5 cm did not significantly differ in any outcomes. These results suggest that multiorifice catheters provide superior intermittent bolus continuous peripheral nerve blockade compared with end-hole catheters. For anterolateral approach interscalene catheter placement, there is minimal benefit, either way, to 2.5- or 5-cm blind catheter advancement.

  20. The Pedagogy of Science Teachers from Non-Natural Science Backgrounds

    ERIC Educational Resources Information Center

    Woods, Shaneka

    2017-01-01

    This is a descriptive, exploratory, qualitative, collective case study that explores the pedagogical practices of science teachers who do not hold natural science degrees. The intent of this study is to support the creation of alternative pathways for recruiting and retaining high-quality secondary science teachers in K-12 education. The…

  1. New endoscopic classification of the cardiac orifice in esophageal achalasia: Champagne glass sign.

    PubMed

    Gomi, Kuniyo; Inoue, Haruhiro; Ikeda, Haruo; Bechara, Robert; Sato, Chiaki; Ito, Hiroaki; Onimaru, Manabu; Kitamura, Yohei; Suzuki, Michitaka; Nakamura, Jun; Hata, Yoshitaka; Maruyama, Shota; Sumi, Kazuya; Takahashi, Hiroshi

    2016-09-01

    Endoscopy, barium esophagram and manometry are used in the diagnosis of achalasia. In the case of early achalasia, characteristic endoscopic findings are difficult to recognize. As a result, the diagnosis of achalasia is often made several years after symptom onset. Therefore, we examined the endoscopic findings of the cardiac orifice in achalasia and propose a new classification. A total of 400 patients with spastic esophageal motility disorders who underwent peroral endoscopic myotomy (POEM) at our hospital between March 2014 and August 2015 were screened for this study. Champagne glass sign (CG) was defined as when the distal end of the lower esophageal sphincter relaxation failure (LESRF) was proximal to the squamocolumnar junction (SCJ) and the SCJ was dilated in the retroflex view. Specifically, CG-1 was defined as a distance from the SCJ to the lower end of LESRF of <1 cm, and CG-2 was defined as a distance ≥1 cm. CG-0 was seen in 73 patients (28.0%), whereas the CG sign was seen in 186 patients (71.3%), of whom 170 (65.1%) were CG-1 and 16 (6.1%) were CG-2. The CG sign is often observed in esophageal achalasia patients. CG-0 (equal to Maki-tsuki) was observed in 28.0% of achalasia patients only. Its absence with dilated SCJ cannot be used to rule out achalasia. Barium esophagram and manometry should be done if esophageal achalasia is strongly suspected. © 2016 Japan Gastroenterological Endoscopy Society.

  2. Characterizing the True Background Corona with SDO/AIA

    NASA Technical Reports Server (NTRS)

    Napier, Kate; Winebarger, Amy; Alexander, Caroline

    2014-01-01

    Characterizing the nature of the solar coronal background would enable scientists to more accurately determine plasma parameters, and may lead to a better understanding of the coronal heating problem. Because scientists study the 3D structure of the Sun in 2D, any line of sight includes both foreground and background material, and thus, the issue of background subtraction arises. By investigating the intensity values in and around an active region, using multiple wavelengths collected from the Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory (SDO) over an eight-hour period, this project aims to characterize the background as smooth or structured. Different methods were employed to measure the true coronal background and create minimum intensity images. These were then investigated for the presence of structure. The background images created were found to contain long-lived structures, including coronal loops, that were still present in all of the wavelengths, 193 Angstroms,171 Angstroms,131 Angstroms, and 211 Angstroms. The intensity profiles across the active region indicate that the background is much more structured than previously thought.

  3. Temporal naturalism

    NASA Astrophysics Data System (ADS)

    Smolin, Lee

    2015-11-01

    Two people may claim both to be naturalists, but have divergent conceptions of basic elements of the natural world which lead them to mean different things when they talk about laws of nature, or states, or the role of mathematics in physics. These disagreements do not much affect the ordinary practice of science which is about small subsystems of the universe, described or explained against a background, idealized to be fixed. But these issues become crucial when we consider including the whole universe within our system, for then there is no fixed background to reference observables to. I argue here that the key issue responsible for divergent versions of naturalism and divergent approaches to cosmology is the conception of time. One version, which I call temporal naturalism, holds that time, in the sense of the succession of present moments, is real, and that laws of nature evolve in that time. This is contrasted with timeless naturalism, which holds that laws are immutable and the present moment and its passage are illusions. I argue that temporal naturalism is empirically more adequate than the alternatives, because it offers testable explanations for puzzles its rivals cannot address, and is likely a better basis for solving major puzzles that presently face cosmology and physics. This essay also addresses the problem of qualia and experience within naturalism and argues that only temporal naturalism can make a place for qualia as intrinsic qualities of matter.

  4. Supercritical Fluid Chromatography--Theoretical Background and Applications on Natural Products.

    PubMed

    Hartmann, Anja; Ganzera, Markus

    2015-11-01

    The use of supercritical fluid chromatography for natural product analysis as well as underlying theoretical mechanisms and instrumental requirements are summarized in this review. A short introduction focusing on the historical development of this interesting separation technique is followed by remarks on the current instrumental design, also describing possible detection modes and useable stationary phases. The overview on relevant applications is grouped based on their basic intention, may it be (semi)preparative or purely analytical. They indicate that supercritical fluid chromatography is still primarily considered for the analysis of nonpolar analytes like carotenoids, fatty acids, or terpenes. The low polarity of supercritical carbon dioxide, which is used with modifiers almost exclusively as a mobile phase today, combined with high efficiency and fast separations might explain the popularity of supercritical fluid chromatography for the analysis of these compounds. Yet, it has been shown that more polar natural products (e.g., xanthones, flavonoids, alkaloids) are separable too, with the same (if not superior) selectivity and reproducibility than established approaches like HPLC or GC. Georg Thieme Verlag KG Stuttgart · New York.

  5. NLPReViz: an interactive tool for natural language processing on clinical text.

    PubMed

    Trivedi, Gaurav; Pham, Phuong; Chapman, Wendy W; Hwa, Rebecca; Wiebe, Janyce; Hochheiser, Harry

    2018-01-01

    The gap between domain experts and natural language processing expertise is a barrier to extracting understanding from clinical text. We describe a prototype tool for interactive review and revision of natural language processing models of binary concepts extracted from clinical notes. We evaluated our prototype in a user study involving 9 physicians, who used our tool to build and revise models for 2 colonoscopy quality variables. We report changes in performance relative to the quantity of feedback. Using initial training sets as small as 10 documents, expert review led to final F1scores for the "appendiceal-orifice" variable between 0.78 and 0.91 (with improvements ranging from 13.26% to 29.90%). F1for "biopsy" ranged between 0.88 and 0.94 (-1.52% to 11.74% improvements). The average System Usability Scale score was 70.56. Subjective feedback also suggests possible design improvements. © The Author 2017. Published by Oxford University Press on behalf of the American Medical Informatics Association. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  6. A three-dimensional semi-analytical solution for predicting drug release through the orifice of a spherical device.

    PubMed

    Simon, Laurent; Ospina, Juan

    2016-07-25

    Three-dimensional solute transport was investigated for a spherical device with a release hole. The governing equation was derived using the Fick's second law. A mixed Neumann-Dirichlet condition was imposed at the boundary to represent diffusion through a small region on the surface of the device. The cumulative percentage of drug released was calculated in the Laplace domain and represented by the first term of an infinite series of Legendre and modified Bessel functions of the first kind. Application of the Zakian algorithm yielded the time-domain closed-form expression. The first-order solution closely matched a numerical solution generated by Mathematica(®). The proposed method allowed computation of the characteristic time. A larger surface pore resulted in a smaller effective time constant. The agreement between the numerical solution and the semi-analytical method improved noticeably as the size of the orifice increased. It took four time constants for the device to release approximately ninety-eight of its drug content. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Anatomic regurgitant orifice area obtained using 3D-echocardiography as an indicator of severity of mitral regurgitation in dogs with myxomatous mitral valve disease.

    PubMed

    Müller, S; Menciotti, G; Borgarelli, M

    2017-10-01

    To determine feasibility and repeatability of measuring the anatomic regurgitant orifice area (AROA) using real-time three-dimensional transthoracic echocardiography (RT3DE) in dogs with myxomatous mitral valve disease (MMVD), and to investigate differences in the AROA of dogs with different disease severity and in different American College of Veterinary Internal Medicine (ACVIM) stages. Sixty privately-owned dogs diagnosed with MMVD. The echocardiographic database of our institution was retrospectively searched for dogs diagnosed with MMVD and RT3DE data set acquisition. Dogs were classified into mild, moderate, or severe MMVD according to a Mitral Regurgitation Severity Score (MRSS), and into stage B1, B2 or C according to ACVIM staging. The RT3DE data sets were imported into dedicated software and a short axis plane crossing the regurgitant orifice was used to measure the AROA. Feasibility, inter- and intra-observer variability of measuring the AROA was calculated. Differences in the AROA between dogs in different MRSS and ACVIM stages were investigated. The AROA was measurable in 60 data sets of 81 selected to be included in the study (74%). The inter- and intra-observer coefficients of variation were 26% and 21%, respectively. The AROA was significantly greater in dogs with a severe MRSS compared with dogs with mild MRSS (p=0.045). There was no difference between the AROA of dogs in different ACVIM clinical stages. Obtaining the AROA using RT3DE is feasible and might provide additional information to stratify mitral regurgitation severity in dogs with MMVD. Diagnostic and prognostic utility of the AROA deserves further investigation. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Long-term outcome of patients with distal ulcerative colitis and inflammation of the appendiceal orifice.

    PubMed

    Naves, Juan E; Lorenzo-Zúñiga, Vicente; Marín, Laura; Mañosa, Míriam; Oller, Blanca; Moreno, Vicente; Zabana, Yamile; Boix, Jaume; Cabré, Eduard; Domènech, Eugeni

    2011-12-01

    Skip inflammation of the appendiceal orifice has been described in distal UC (UC-IAO) but long-term clinical outcomes are poorly established. Our aim was to evaluate the long-term clinical outcomes of UC-IAO as compared to classic distal UC. Patients with UC-IAO were identified from the local IBD database. Disease outcome and therapeutic requirements during follow-up were accurately collected, and compared with a control group of patients with distal UC without peri-appendiceal involvement matched by disease extent (proctitis/distal), smoking habit, and date and age at diagnosis. Fourteen UC patients were found to have UC-IAO, most of them with initial extent of UC limited to the rectum. All patients were initially managed with mesalazine administered orally (28.5%), topically (28.5%), or in combination (43%). After a median follow-up of 78 months (interquartile range--IQR 45-123) most UC-IAO patients were successfully managed with oral and/or topical aminosalicylates. Only one of them developed proximal disease progression. As compared to controls, no differences in clinical outcomes or therapeutic requirements were found. Patients with UC-IAO tend to present a mild course, with a low probability to develop proximal progression of disease extent or to require immunosuppressive therapy or colectomy.

  9. Correlation between the silica concentration and the orifice temperature in the warm springs along the jordan-dead sea rift valley

    USGS Publications Warehouse

    Levitte, D.; Eckstein, Y.

    1978-01-01

    Analysis of twenty-one thermal springs emerging along the Jordan-Dead Sea Rift Valley in Israel indicates a very good correlation between the concentration of dissolved silica and the temperature of the spring orifice. Dissolution of quartz was identified as the apparent source of the silica in the water. Application of the silica geothermometer for mixed systems suggests that the springs in the Tiberias Lake Basin are supplied with hot water from deep reservoir (or reservoirs) at a temperature of 115??C (239??F). The same temperature was postulated earlier by the application of the Na-K-Ca hydro-geothermometer to a group of thermal springs in the same basin. The temperature of the reservoir supplying hot brines to the springs emerging along the western shore of the Dead Sea is estimated at 90??C (194??F).

  10. In-Home Respite Care Program Development. Background. Coordinator's Manual. Training Manual.

    ERIC Educational Resources Information Center

    Parham, J. D.; And Others

    This volume consists of a background discussion, coordinator's manual, and training manual dealing with developing programs for the in-home respite care (IHRC) of the developmentally disabled. Addressed in the background information unit are the nature of developmental disabilities; program variables, planning, and funding; and practical…

  11. Residential Exposure to Natural Background Radiation and Risk of Childhood Acute Leukemia in France, 1990-2009.

    PubMed

    Demoury, Claire; Marquant, Fabienne; Ielsch, Géraldine; Goujon, Stéphanie; Debayle, Christophe; Faure, Laure; Coste, Astrid; Laurent, Olivier; Guillevic, Jérôme; Laurier, Dominique; Hémon, Denis; Clavel, Jacqueline

    2017-04-01

    Exposures to high-dose ionizing radiation and high-dose rate ionizing radiation are established risk factors for childhood acute leukemia (AL). The risk of AL following exposure to lower doses due to natural background radiation (NBR) has yet to be conclusively determined. AL cases diagnosed over 1990-2009 (9,056 cases) were identified and their municipality of residence at diagnosis collected by the National Registry of Childhood Cancers. The Geocap study, which included the 2,763 cases in 2002-2007 and 30,000 population controls, was used for complementary analyses. NBR exposures were modeled on a fine scale (36,326 municipalities) based on measurement campaigns and geological data. The power to detect an association between AL and dose to the red bone marrow (RBM) fitting UNSCEAR (United Nations Scientific Committee on the Effects of Atomic Radiation) predictions was 92%, 45% and 99% for exposure to natural gamma radiation, radon and total radiation, respectively. AL risk, irrespective of subtype and age group, was not associated with the exposure of municipalities to radon or gamma radiation in terms of yearly exposure at age reached, cumulative exposure or RBM dose. There was no confounding effect of census-based socio-demographic indicators, or environmental factors (road traffic, high voltage power lines, vicinity of nuclear plants) related to AL in the Geocap study. Our findings do not support the hypothesis that residential exposure to NBR increases the risk of AL, despite the large size of the study, fine scale exposure estimates and wide range of exposures over France. However, our results at the time of diagnosis do not rule out a slight association with gamma radiation at the time of birth, which would be more in line with the recent findings in the UK and Switzerland.

  12. Of the necessity of knowledge of the natural pedo-geochemical background content in the evaluation of the contamination of soils by trace elements.

    PubMed

    Baize, D; Sterckeman, T

    2001-01-08

    In order to evaluate the contamination of the Dornach (Switzerland) site within the framework of the CEEM-Soil project, each participating team was allowed to take a maximum of 15 samples. The French team's sampling was organized in such a way as to answer the following questions: (i) what is the natural concentration of the soils at this site (local pedo-geochemical background content)?; (ii) what are the levels of Cd, Cu, Pb and Zn contamination of the soil?; (iii) what is the depth reached by the surface contamination that is derived from atmospheric fallout?; (iv) how is the contamination spread along the longest axis of the area under study? The relationships between total Fe and the trace metals have allowed local variations in the natural pedo-geochemical background content to be detected and thus permitted the anthropogenic contamination to be estimated. There would appear to be a low level of Pb contamination over all the site investigated (an increase of the order of 5-10 mg kg(-1) on the background level), limited to the surface humus-bearing layers. There is also a significant contamination by Cu over all of the site (an increase of the order of 30-40 mg kg(-1)). This contamination has remained in the surface horizons (0-20 cm). Very high Zn and Cd concentrations have been found in the four surface (0-4 cm) and deep horizons (15-70 cm) taken under the forest and very much lower values in the samples taken from cultivated soils. The most likely explanation is an unequal inheritance between the upper part of the site (wooded with thinner very clayey soils) and the lower cultivated part of the site (with thicker less clayey soils developed in a loamy material). For various reasons, it seems unlikely that a contamination of the wooded part should be so much higher than the cultivated part due to the interception of atmospheric dust by the trees. The local pedo-geochemical background Cd and Zn content of the upper wooded part proved to be clearly higher than

  13. Gamma-Ray Background Variability in Mobile Detectors

    NASA Astrophysics Data System (ADS)

    Aucott, Timothy John

    Gamma-ray background radiation significantly reduces detection sensitivity when searching for radioactive sources in the field, such as in wide-area searches for homeland security applications. Mobile detector systems in particular must contend with a variable background that is not necessarily known or even measurable a priori. This work will present measurements of the spatial and temporal variability of the background, with the goal of merging gamma-ray detection, spectroscopy, and imaging with contextual information--a "nuclear street view" of the ubiquitous background radiation. The gamma-ray background originates from a variety of sources, both natural and anthropogenic. The dominant sources in the field are the primordial isotopes potassium-40, uranium-238, and thorium-232, as well as their decay daughters. In addition to the natural background, many artificially-created isotopes are used for industrial or medical purposes, and contamination from fission products can be found in many environments. Regardless of origin, these backgrounds will reduce detection sensitivity by adding both statistical as well as systematic uncertainty. In particular, large detector arrays will be limited by the systematic uncertainty in the background and will suffer from a high rate of false alarms. The goal of this work is to provide a comprehensive characterization of the gamma-ray background and its variability in order to improve detection sensitivity and evaluate the performance of mobile detectors in the field. Large quantities of data are measured in order to study their performance at very low false alarm rates. Two different approaches, spectroscopy and imaging, are compared in a controlled study in the presence of this measured background. Furthermore, there is additional information that can be gained by correlating the gamma-ray data with contextual data streams (such as cameras and global positioning systems) in order to reduce the variability in the background

  14. Statistical nature of infrared dynamics on de Sitter background

    NASA Astrophysics Data System (ADS)

    Tokuda, Junsei; Tanaka, Takahiro

    2018-02-01

    In this study, we formulate a systematic way of deriving an effective equation of motion(EoM) for long wavelength modes of a massless scalar field with a general potential V(phi) on de Sitter background, and investigate whether or not the effective EoM can be described as a classical stochastic process. Our formulation gives an extension of the usual stochastic formalism to including sub-leading secular growth coming from the nonlinearity of short wavelength modes. Applying our formalism to λ phi4 theory, we explicitly derive an effective EoM which correctly recovers the next-to-leading secularly growing part at a late time, and show that this effective EoM can be seen as a classical stochastic process. Our extended stochastic formalism can describe all secularly growing terms which appear in all correlation functions with a specific operator ordering. The restriction of the operator ordering will not be a big drawback because the commutator of a light scalar field becomes negligible at large scales owing to the squeezing.

  15. Background radiation measurements at high power research reactors

    DOE PAGES

    Ashenfelter, J.; Yeh, M.; Balantekin, B.; ...

    2015-10-23

    Research reactors host a wide range of activities that make use of the intense neutron fluxes generated at these facilities. Recent interest in performing measurements with relatively low event rates, e.g. reactor antineutrino detection, at these facilities necessitates a detailed understanding of background radiation fields. Both reactor-correlated and naturally occurring background sources are potentially important, even at levels well below those of importance for typical activities. Here we describe a comprehensive series of background assessments at three high-power research reactors, including γ-ray, neutron, and muon measurements. For each facility we describe the characteristics and identify the sources of the backgroundmore » fields encountered. Furthermore, the general understanding gained of background production mechanisms and their relationship to facility features will prove valuable for the planning of any sensitive measurement conducted therein.« less

  16. Geochemistry, biota and natural background levels in an arsenic naturally contaminated volcanic aquifer

    NASA Astrophysics Data System (ADS)

    Preziosi, Elisabetta; Amalfitano, Stefano; Di Lorenzo, Tiziana; Parrone, Daniele; Rossi, David; Ghergo, Stefano; Lungarini, Silvia; Zoppini, Anna Maria

    2015-04-01

    The tight links between chemical and ecological status are largely acknowledged as for surface water bodies, while aquifers are still considered as hidden groundwater reservoirs, rather than ecosystems to be preserved. Geochemical and biological interactions play a key role in all subterranean processes, including the dynamics of the fate of anthropogenic contaminants. Studies on groundwater dependent ecosystems (GDE) were mainly focused on karst aquifers so far, but an increased awareness on the importance of water-rock interactions and methodological improvements in microbial ecology are rapidly increasing the level of characterization of groundwater ecosystems in various hydrogeological contexts. Similarly, knowledge about groundwater biodiversity is still limited, especially if porous habitats are concerned. Yet, groundwater and GDEs are populated by a diverse and highly adapted biota, dominated by crustaceans, which provide important ecosystem services and act as biological indicators of chemical and quantitative impact on groundwater resources. In a previous research (Amalfitano et al. 2014), we reported that the microbial community heterogeneity may reflect the lithological and hydrogeological complexity within volcanic and alluvial facies transition in a groundwater body. The quantitative tracking of the microbial community structure allowed disentangling the natural biogeochemical processes evolving within the aquifer flow path. The analyses of groundwater crustaceans assemblages may contribute to shed more light upon the state and dynamics of such ecosystems. In the present research, a comprehensive study of a water table aquifer flowing through a quaternary volcanic district is being performed, including the geochemical (inorganic) composition, the microbial composition, and the analysis of crustacean assemblages . Groundwater samples are periodically collected from private wells and springs under a low anthropic impact. The key issues within the

  17. Assessing Natural Background Levels of aquifers in the Metropolitan Area of Milan (Lombardy)

    NASA Astrophysics Data System (ADS)

    De Caro, Mattia; Crosta, Giovanni; Frattini, Paolo

    2016-04-01

    The European Water Framework Directive (WFD 2000/60/CE) requires Member States to evaluate the status of groundwater bodies in order to reach a good water quality for human consumption. One of the preliminary steps for defining the status of groundwater bodies consists in the definition and evaluation of the so-called Natural Background Levels (NBL). The NBL or Baseline level can be defined as "the range of concentration of a given element, isotope or chemical compound in solution, derived entirely from natural, geological, biological or atmospheric sources, under conditions not perturbed by anthropogenic activity" (Edmund and Shand, 2009). The qualitative analysis for a large area (ca 4500 Km2) of the Po Plain around the Milan Metropolitan area (Lombardy, Italy) is presented in this study. Despite the aquifers in the Milan metropolitan area are an incredible groundwater resource for a very large population (3.195.629 inhabitants in the metropolitan area, data at November 2014) and a highly industrialized area, a groundwater baseline characterization is still missing. In order to attain the hydro-geochemical characterization a complete geodatabase was built (120.655 chemical samples from 1980 to 2014). This database has been explored by classical and multivariate statistical analyses to provide relationships among the more influential lithological, hydrogeological and hydro-chemical variables. Finally, the NBLs of different chemical species which may be anthropogenic sensitive (Na, Cl, K, NO3, SO4, NH4, As, Fe, Cr, Fe, Mn, Zn) and for multiple aquifer bodies (phreatic, semi-confined and confined aquifer) are evaluated. Two different approaches are applied: the Pre-Selection method (BRIDGE, 2006) and the Component-Separation method. The first one (PS) consists in the exclusion of samples from the available dataset that could indicate human activities then deriving the NBL as the 90th percentile of the remaining data. The second one (CS) consists in the fitting of

  18. Balanced Flow Measurement and Conditioning Technology (Balanced Orifice Plate 7,051,765 B1) for NASA Inventions and Contributions Board Invention of the Year Evaluation

    NASA Technical Reports Server (NTRS)

    Kelley, Anthony R.

    2008-01-01

    This viewgraph document reviews the Balanced Flow Measurement (BFM) and Conditioning Technology, and makes the case for this as the NASA Invention of the Year. The BFM technology makes use of a thin, multi-hole orifice plate with holes sized and placed per a unique set of equations. It produces mass flow, volumetric flow,kinelic energy,or momentum BALANCE across the face of the plate. The flow is proportional.to the square root of upstream to downstream differential pressure. Multiple holes lead to smoother pressure measurement. Measures and conditions or can limit fluid flow. This innovation has many uses in and out of NASA.

  19. Natural Covariant Planck Scale Cutoffs and the Cosmic Microwave Background Spectrum.

    PubMed

    Chatwin-Davies, Aidan; Kempf, Achim; Martin, Robert T W

    2017-07-21

    We calculate the impact of quantum gravity-motivated ultraviolet cutoffs on inflationary predictions for the cosmic microwave background spectrum. We model the ultraviolet cutoffs fully covariantly to avoid possible artifacts of covariance breaking. Imposing these covariant cutoffs results in the production of small, characteristically k-dependent oscillations in the spectrum. The size of the effect scales linearly with the ratio of the Planck to Hubble lengths during inflation. Consequently, the relative size of the effect could be as large as one part in 10^{5}; i.e., eventual observability may not be ruled out.

  20. Effect of load alterations on the effective regurgitant orifice area in chronic aortic regurgitation.

    PubMed

    Kim, Y J; Jones, M; Shiota, T; Tsujino, H; Qin, J X; Bauer, F; Sitges, M; Kwan, J; Cardon, L A; Zetts, A D; Thomas, J D

    2002-10-01

    To evaluate the load dependence of effective regurgitant orifice area (ROA) in an animal model of chronic aortic regurgitation. Eight sheep were studied 10-20 weeks after the surgical creation of aortic regurgitation. After baseline studies, 500 ml of blood, angiotensin II, and nitroprusside were infused sequentially. Electromagnetic flow meters were used as reference standards to determine aortic regurgitation volume. The time-velocity integral was acquired using the continuous wave Doppler method. Baseline aortic regurgitant volume varied from 8 ml (regurgitant fraction 28%) to 29 ml (59%), with a mean (SD) value of 17 (8) ml; mean ROA was 0.15 (0.05) cm2. During angiotensin II infusion, aortic regurgitation volume (20 (8) ml) and mean diastolic aortoventricular pressure gradient (62 (18) mm Hg) increased by 26 (16)% and 48 (64)%, respectively (p < 0.01 for both). ROA did not change (0.16 (0.06) cm(2), p = 0.15). During nitroprusside infusion, aortic regurgitant volume (13 (7) ml, p = 0.05) and diastolic pressure gradient (25 (13) mm Hg, p < 0.05) decreased. ROA did not change (0.15 (0.05) cm2). When analysing 32 stages together, aortic regurgitant volume (r = 0.78, p < 0.01) and regurgitant fraction (r = 0.55, p < 0.01) correlated well with ROA. However, diastolic pressure gradient (r = 0.28) was not significantly correlated with ROA. In an animal model of chronic aortic regurgitation, ROA did not change with load alterations.

  1. Left Atrial Appendage Eccentricity and Irregularity Are Associated With Residual Leaks After Percutaneous Closure.

    PubMed

    Rajwani, Adil; Shirazi, Masoumeh G; Disney, Patrick J S; Wong, Dennis T L; Teo, Karen S L; Delacroix, Sinny; Chokka, Ramesh G; Young, Glenn D; Worthley, Stephen G

    2015-12-01

    Predictors of residual leak following percutaneous LAA closure were evaluated. Left atrial appendage (LAA) closure aims to exclude this structure from the circulation, typically using a circular occluder. A noncircular orifice is frequently encountered however, and fibrous remodeling of the LAA in atrial fibrillation may restrict orifice deformation. Noncircularity may thus be implicated in the occurrence of residual leak despite an appropriately oversized device. Pre-procedural multislice computerized tomography was used to quantify LAA orifice eccentricity and irregularity. Univariate predictors of residual leak were identified with respect to the orifice, device, and relevant clinical variables, with the nature of any correlations then further evaluated. Eccentricity and irregularity indexes of the orifice in 31 individuals were correlated with residual leak even where the device was appropriately oversized. An eccentricity index of 0.15 predicted a residual leak with 85% sensitivity and 59% specificity. An irregularity index of 0.05 predicted a significant residual leak ≥3 mm with 100% sensitivity and 86% specificity. Orifice size, device size, degree of device oversize, left atrial volume, and pulmonary artery pressure were not predictors of residual leak. Eccentricity and irregularity of the LAA orifice are implicated in residual leak after percutaneous closure even where there is appropriate device over-size. Irregularity index in particular is a novel predictor of residual leak, supporting a closer consideration of orifice morphology before closure. Copyright © 2015 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  2. Input comparison of radiogenic neutron estimates for ultra-low background experiments

    NASA Astrophysics Data System (ADS)

    Cooley, J.; Palladino, K. J.; Qiu, H.; Selvi, M.; Scorza, S.; Zhang, C.

    2018-04-01

    Ultra-low-background experiments address some of the most important open questions in particle physics, cosmology and astrophysics: the nature of dark matter, whether the neutrino is its own antiparticle, and does the proton decay. These rare event searches require well-understood and minimized backgrounds. Simulations are used to understand backgrounds caused by naturally occurring radioactivity in the rock and in every piece of shielding and detector material used in these experiments. Most important are processes like spontaneous fission and (α,n) reactions in material close to the detectors that can produce neutrons. A comparison study of the (α,n) reactions between two dedicated software packages is detailed. The cross section libraries, neutron yields, and spectra from the Mei-Zhang-Hime and the SOURCES-4A codes are presented. The resultant yields and spectra are used as inputs to direct dark matter detector toy models in GEANT4, to study the impact of their differences on background estimates and fits. Although differences in neutron yield calculations up to 50% were seen, there was no systematic difference between the Mei-Hime-Zhang and SOURCES-4A results. Neutron propagation simulations smooth differences in spectral shape and yield, and both tools were found to meet the broad requirements of the low-background community.

  3. A record-based case-control study of natural background radiation and the incidence of childhood leukaemia and other cancers in Great Britain during 1980-2006.

    PubMed

    Kendall, G M; Little, M P; Wakeford, R; Bunch, K J; Miles, J C H; Vincent, T J; Meara, J R; Murphy, M F G

    2013-01-01

    We conducted a large record-based case-control study testing associations between childhood cancer and natural background radiation. Cases (27,447) born and diagnosed in Great Britain during 1980-2006 and matched cancer-free controls (36,793) were from the National Registry of Childhood Tumours. Radiation exposures were estimated for mother's residence at the child's birth from national databases, using the County District mean for gamma rays, and a predictive map based on domestic measurements grouped by geological boundaries for radon. There was 12% excess relative risk (ERR) (95% CI 3, 22; two-sided P=0.01) of childhood leukaemia per millisievert of cumulative red bone marrow dose from gamma radiation; the analogous association for radon was not significant, ERR 3% (95% CI -4, 11; P=0.35). Associations for other childhood cancers were not significant for either exposure. Excess risk was insensitive to adjustment for measures of socio-economic status. The statistically significant leukaemia risk reported in this reasonably powered study (power ~50%) is consistent with high-dose rate predictions. Substantial bias is unlikely, and we cannot identify mechanisms by which confounding might plausibly account for the association, which we regard as likely to be causal. The study supports the extrapolation of high-dose rate risk models to protracted exposures at natural background exposure levels.

  4. Qatar: Background and U.S. Relations

    DTIC Science & Technology

    2010-05-05

    pending completion of the long-planned expansion of liquefied natural gas (LNG) output to 78 million tones per year is expected to buoy public revenue...study the effects of completed projects on the country’s gas reserves and to plan for efficient management of gas resources for the future. Many...45 Meeting with Qatar Petroleum , Qatar Gas , and Ras Gas executives, Ras Laffan, Qatar, January 2005. . Qatar: Background and U.S. Relations

  5. Constrained sampling experiments reveal principles of detection in natural scenes.

    PubMed

    Sebastian, Stephen; Abrams, Jared; Geisler, Wilson S

    2017-07-11

    A fundamental everyday visual task is to detect target objects within a background scene. Using relatively simple stimuli, vision science has identified several major factors that affect detection thresholds, including the luminance of the background, the contrast of the background, the spatial similarity of the background to the target, and uncertainty due to random variations in the properties of the background and in the amplitude of the target. Here we use an experimental approach based on constrained sampling from multidimensional histograms of natural stimuli, together with a theoretical analysis based on signal detection theory, to discover how these factors affect detection in natural scenes. We sorted a large collection of natural image backgrounds into multidimensional histograms, where each bin corresponds to a particular luminance, contrast, and similarity. Detection thresholds were measured for a subset of bins spanning the space, where a natural background was randomly sampled from a bin on each trial. In low-uncertainty conditions, both the background bin and the amplitude of the target were fixed, and, in high-uncertainty conditions, they varied randomly on each trial. We found that thresholds increase approximately linearly along all three dimensions and that detection accuracy is unaffected by background bin and target amplitude uncertainty. The results are predicted from first principles by a normalized matched-template detector, where the dynamic normalizing gain factor follows directly from the statistical properties of the natural backgrounds. The results provide an explanation for classic laws of psychophysics and their underlying neural mechanisms.

  6. EMR of laterally spreading lesions around or involving the appendiceal orifice: technique, risk factors for failure, and outcomes of a tertiary referral cohort (with video).

    PubMed

    Tate, David J; Desomer, Lobke; Awadie, Halim; Goodrick, Kathleen; Hourigan, Luke; Singh, Rajvinder; Williams, Stephen J; Bourke, Michael J

    2018-05-01

    EMR of sessile periappendiceal laterally spreading lesions (PA-LSLs) is technically demanding because of poor endoscopic access to the appendiceal lumen and the thin colonic wall at the base of the cecum. We aimed to assess the feasibility and safety of EMR for PA-LSLs. Consecutive LSLs ≥20 mm and PA-LSLs ≥10 mm detected at 3 academic endoscopy centers from September 2008 until January 2017 were eligible. Prospective patient, procedural, and lesion data were collected. PA-LSLs were compared with LSLs in other colonic locations. Thirty-eight PA-LSLs were compared with 1721 LSLs. Referral for surgery without an attempt at EMR was more likely with PA-LSLs (28.9% vs 5.1%, P < .001), and those that involved a greater percentage of the appendiceal orifice (AO) were less likely to be attempted (P = .038). Most PA-LSLs (10/11) were not attempted because of deep extension into the appendiceal lumen; 2 of 11 of these surgical specimens contained invasive cancer. Once attempted, complete clearance of visible adenoma (92.6% PA-LSLs vs 97.6% LSLs, P = .14), adverse events, and rates of adenoma recurrence did not vary significantly between PA-LSLs and LSLs. All 7 patients with prior appendicectomy achieved complete adenoma clearance. There were no cases of post-EMR appendicitis. Twenty of 22 PA-LSLs (91%) eligible for surveillance avoided surgery to longest follow-up. EMR is a safe, effective, and durable treatment for PA-LSLs when specific criteria are fulfilled. If the distal margin of the PA-LSL within the AO cannot be visualized or if more than 50% of the circumference of the orifice is involved, surgery should be considered. (Clinical trial registration number: NTC01368289.). Copyright © 2018. Published by Elsevier Inc.

  7. The Cosmic Microwave Background Anisotropy

    NASA Astrophysics Data System (ADS)

    Bennett, C. L.

    1994-12-01

    The properties of the cosmic microwave background radiation provide unique constraints on the history and evolution of the universe. The first detection of anisotropy of the microwave radiation was reported by the COBE Team in 1992, based on the first year of flight data. The latest analyses of the first two years of COBE data are reviewed in this talk, including the amplitude of the microwave anisotropy as a function of angular scale and the statistical nature of the fluctuations. The two-year results are generally consistent with the earlier first year results, but the additional data allow for a better determination of the key cosmological parameters. In this talk the COBE results are compared with other observational anisotropy results and directions for future cosmic microwave anisotropy observations will be discussed. The National Aeronautics and Space Administration/Goddard Space Flight Center (NASA/GSFC) is responsible for the design, development, and operation of the Cosmic Background Explorer (COBE). Scientific guidance is provided by the COBE Science Working Group.

  8. Research yields precise uncertainty equations

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Jones, E.H.; Ferguson, K.R.

    1987-08-03

    Results of a study of orifice-meter accuracy by Chevron Oil Field Research Co. at its Venice, La., calibration facility have important implications for natural gas custody-transfer measurement. The calibration facility, data collection, and equipment calibration were described elsewhere. This article explains the derivation of uncertainty factors and details the study's findings. The results were based on calibration of two 16-in. orifice-meter runs. The experimental data cover a beta-ratio range of from 0.27 to 0.71 and a Reynolds number range of from 4,000,000 to 35,000,000. Discharge coefficients were determined by comparing the orifice flow to the flow from critical-flow nozzles.

  9. Combining natural background levels (NBLs) assessment with indicator kriging analysis to improve groundwater quality data interpretation and management.

    PubMed

    Ducci, Daniela; de Melo, M Teresa Condesso; Preziosi, Elisabetta; Sellerino, Mariangela; Parrone, Daniele; Ribeiro, Luis

    2016-11-01

    The natural background level (NBL) concept is revisited and combined with indicator kriging method to analyze the spatial distribution of groundwater quality within a groundwater body (GWB). The aim is to provide a methodology to easily identify areas with the same probability of exceeding a given threshold (which may be a groundwater quality criteria, standards, or recommended limits for selected properties and constituents). Three case studies with different hydrogeological settings and located in two countries (Portugal and Italy) are used to derive NBL using the preselection method and validate the proposed methodology illustrating its main advantages over conventional statistical water quality analysis. Indicator kriging analysis was used to create probability maps of the three potential groundwater contaminants. The results clearly indicate the areas within a groundwater body that are potentially contaminated because the concentrations exceed the drinking water standards or even the local NBL, and cannot be justified by geogenic origin. The combined methodology developed facilitates the management of groundwater quality because it allows for the spatial interpretation of NBL values. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. Background Data Measures for Predicting Security Risks: A Construct Approach

    DTIC Science & Technology

    1992-01-01

    Emmons, 1987). 5. Mach V (Christie & Geis, 1970). 6. Authoritarianism (Dillehay, 1978Y. 7. Background Data Questionnaire (Owens & Schoenfeldt, 1979...z~ 40 SI) ) I~~~F In qTIC 5 C ~C-C UU T f < V) u u. .<: 0. 22 untrusting nature of authoritarians , it was found that our...background data measure of authoritarianism was positively related to negative beliefs about humanity (r = .46), negative beliefs about outcomes (r = .39

  11. An Assessment on Temperature Profile of Jet-A/Biodiesel Mixture in a Simple Combustion Chamber with Plain Orifice Atomiser

    NASA Astrophysics Data System (ADS)

    Ng, W. X.; Mazlan, N. M.; Ismail, M. A.; Rajendran, P.

    2018-05-01

    The preliminary study to evaluate influence of biodiesel/kerosene mixtures on combustion temperature profile is explored. A simple cylindrical combustion chamber configuration with plain orifice atomiser is used for the evaluation. The evaluation is performed under stoichiometric air to fuel ratio. Six samples of fuels are used: 100BD (pure biodiesel), 100KE (pure Jet-A), 20KE80BD (20% Jet-A/80% Biodiesel), 40KE60BD (40% Jet-A/60% Biodiesel), 60KE40BD (60% Jet-A/40% Biodiesel), and 80KE20BD (80% Jet-A/20% Biodiesel). Results showed that the oxygen content, viscosity, and lower heating value are key parameters in affecting the temperature profile inside the chamber. Biodiesel is known to have higher energy content, higher viscosity and lower heating value compared to kerosene. Mixing biodiesel with kerosene improves viscosity and caloric value but reduces oxygen content of the fuel. High oxygen content of the biodiesel resulted to the highest flame temperature. However the flame temperature reduce as the percentage of biodiesel in the fuel mixture reduces.

  12. Grounding a natural background level for fluoride in a potentially contaminated crystalline aquifer in south India.

    PubMed

    Sajil Kumar, P J

    2017-12-01

    Fluoride contamination is one of the most alarming issues for those countries that depend on groundwater drinking water supply. A careful examination of the hydrogeochemical conditions and routine monitoring of fluoride level are therefore quintessential. Estimation of natural background level (NBL) of fluoride becomes significant information for assessing the current and future contamination episodes. Vellore District in Tamil Nadu is a hard rock terrain known for its F-rich groundwater. In this study, we attempted to form a benchmark for fluoride using hydrochemical pre-selection (based on TDS and NO 3 ) and cumulative probability plots (CPP). Principle components analysis is (PCA) applied to evaluate the corresponding factor grouping of the total of 68 samples, which is later mapped using geostatistical tool in ArcGIS. From the CPP, we derived the NBL of F as 0.75 mg/L. This value is compared with the observed concentration in each sample and they were spatially plotted based on the NBL. Resultant plot suggests that W-NW part of the study area has exceeded and E-EW regions are below the NBL of F. Spatial variation of the factor scores also supported this observation. Grounding an NBL and extending it to other parts of the potential contaminated aquifers are highly recommended for better understanding and management of the water supply systems.

  13. Analysis of Alpha Backgrounds in DarkSide-50

    NASA Astrophysics Data System (ADS)

    Monte, Alissa; DarkSide Collaboration

    2017-01-01

    DarkSide-50 is the current phase of the DarkSide direct dark matter search program, operating underground at the Laboratori Nazionali del Gran Sasso in Italy. The detector is a dual-phase argon Time Projection Chamber (TPC), designed for direct detection of Weakly Interacting Massive Particles, and housed within an active veto system of liquid scintillator and water Cherenkov detectors. Since switching to a target of low radioactivity argon extracted from underground sources in April, 2016, the background is no longer dominated by naturally occurring 39Ar. However, alpha backgrounds from radon and its daughters remain, both from the liquid argon bulk and internal detector surfaces. I will present details of the analysis used to understand and quantify alpha backgrounds, as well as to understand other types of radon contamination that may be present, and our sensitivity to them.

  14. Modeling background radiation in Southern Nevada

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Haber, Daniel A.; Burnley, Pamela C.; Adcock, Christopher T.

    Aerial gamma ray surveys are an important tool for national security, scientific, and industrial interests in determining locations of both anthropogenic and natural sources of radioactivity. There is a relationship between radioactivity and geology and in the past this relationship has been used to predict geology from an aerial survey. The purpose of this project is to develop a method to predict the radiologic exposure rate of the geologic materials by creating a high resolution background model. The intention is for this method to be used in an emergency response scenario where the background radiation envi-ronment is unknown. Two studymore » areas in Southern Nevada have been modeled using geologic data, images from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), geochemical data, and pre-existing low resolution aerial surveys from the National Uranium Resource Evaluation (NURE) Survey. Using these data, geospatial areas that are homogenous in terms of K, U, and Th, referred to as background radiation units, are defined and the gamma ray exposure rate is predicted. The prediction is compared to data collected via detailed aerial survey by the Department of Energy's Remote Sensing Lab - Nellis, allowing for the refinement of the technique. By using geologic units to define radiation background units of exposed bedrock and ASTER visualizations to subdivide and define radiation background units within alluvium, successful models have been produced for Government Wash, north of Lake Mead, and for the western shore of Lake Mohave, east of Searchlight, NV.« less

  15. Modeling background radiation in Southern Nevada

    DOE PAGES

    Haber, Daniel A.; Burnley, Pamela C.; Adcock, Christopher T.; ...

    2017-02-06

    Aerial gamma ray surveys are an important tool for national security, scientific, and industrial interests in determining locations of both anthropogenic and natural sources of radioactivity. There is a relationship between radioactivity and geology and in the past this relationship has been used to predict geology from an aerial survey. The purpose of this project is to develop a method to predict the radiologic exposure rate of the geologic materials by creating a high resolution background model. The intention is for this method to be used in an emergency response scenario where the background radiation envi-ronment is unknown. Two studymore » areas in Southern Nevada have been modeled using geologic data, images from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), geochemical data, and pre-existing low resolution aerial surveys from the National Uranium Resource Evaluation (NURE) Survey. Using these data, geospatial areas that are homogenous in terms of K, U, and Th, referred to as background radiation units, are defined and the gamma ray exposure rate is predicted. The prediction is compared to data collected via detailed aerial survey by the Department of Energy's Remote Sensing Lab - Nellis, allowing for the refinement of the technique. By using geologic units to define radiation background units of exposed bedrock and ASTER visualizations to subdivide and define radiation background units within alluvium, successful models have been produced for Government Wash, north of Lake Mead, and for the western shore of Lake Mohave, east of Searchlight, NV.« less

  16. Acquisition and correlation of cryogenic nitrogen mass flow data through a multiple orifice Joule-Thomson device

    NASA Astrophysics Data System (ADS)

    Papell, S. Stephen; Saiyed, Naseem H.; Nyland, Ted W.

    1990-05-01

    Liquid nitrogen mass flow rate, pressure drop, and temperature drop data were obtained for a series of multiple orifice Joule-Thomson devices, known as Visco Jets, over a wide range of flow resistance. The test rig used to acquire the data was designed to minimize heat transfer so that fluid expansion through the Visco Jets would be isenthalpic. The data include a range of fluid inlet pressures from 30 to 60 psia, fluid inlet temperatures from 118 to 164 R, outlet pressures from 2.8 to 55.8 psia, outlet temperatures from 117 to 162 R and flow rate from 0.04 to 4.0 lbm/hr of nitrogen. A flow rate equation supplied by the manufacturer was found to accurately predict single-phase (noncavitating) liquid nitrogen flow through the Visco Jets. For cavitating flow, the manufacturer's equation was found to be inaccurate. Greatly improved results were achieved with a modified version of the single-phase equation. The modification consists of a multiplication factor to the manufacturer's equation equal to one minus the downstream quality on an isenthalpic expansion of the fluid across the Visco Jet. For a range of flow resistances represented by Visco Jet Lohm ratings between 17,600 and 80,000, 100 percent of the single-phase data and 85 percent of the two-phase data fall within + or - 10 percent of predicted values.

  17. A record-based case-control study of natural background radiation and the incidence of childhood leukaemia and other cancers in Great Britain during 1980–2006

    PubMed Central

    Kendall, Gerald M.; Little, Mark P.; Wakeford, Richard; Bunch, Kathryn J.; Miles, Jon C.H.; Vincent, Timothy J.; Meara, Jill R.; Murphy, Michael F.G.

    2014-01-01

    We conducted a large record-based case-control study testing associations between childhood cancer and natural background radiation. Cases (27 447) born and diagnosed in Great Britain during 1980–2006 and matched cancer-free controls (36 793) were from the National Registry of Childhood Tumours. Radiation exposures were estimated for mother’s residence at the child’s birth from national databases, using the County District mean for gamma-rays, and a predictive map based on domestic measurements grouped by geological boundaries for radon. There was 12% excess relative risk (95% CI 3, 22; 2-sided p=0.01) of childhood leukaemia per millisievert of cumulative red-bone-marrow dose from gamma-radiation; the analogous association for radon was not significant, excess relative risk 3% (95% CI −4, 11; p=0.35). Associations for other childhood cancers were not significant for either exposure. Excess risk was insensitive to adjustment for measures of socio-economic status. The statistically significant leukaemia risk reported in this reasonably-powered study (power ~50%) is consistent with high dose-rate predictions. Substantial bias is unlikely, and we cannot identify mechanisms by which confounding might plausibly account for the association, which we regard as likely to be causal. The study supports the extrapolation of high dose-rate risk models to protracted exposures at natural background exposure levels. PMID:22766784

  18. The analysis on the extreme water shortage event in Hangzhou in 1247 AD and its natural and social backgrounds

    NASA Astrophysics Data System (ADS)

    Liu, Haolong

    2017-04-01

    Yangtze River Delta locating in the north subtropics of China, is famous for numerous rivers and lakes. Because of East Asian monsoon rainfall, flood is always the most primary disaster in this area during the past 2000 years. However, there were also several extreme water shortage events in the history. Example in Hangzhou in 1247 AD was such a typical year in the area. In the paper, the severity of this extreme event and the closely tied spatiotemporal variation of drought in Yangtze River Delta was quantitatively analyzed on the basis of documentary records during Southern Song Dynasty. Furtherly, its natural and social backgrounds was discussed. The result s are summarized as follows: 1) Wells, canals and West Lake of Hangzhou dried up in 1247 AD. The water level of canals was about 1.32-2.64 m lower than that in the normal year. The reduction of storage capacity in West Lake was 21 million stere or so. 2) The droughts in Yangtze River Delta was moderate on the whole, but that in the west of Zhejiang Province was severe. The drought in Hangzhou lasted from the 2nd lunar month to the end of this year. 3) The water shortage event was closely related to the quick going north and farther northern location of summer rain belt. The descending sea-level weakening the tide in Qiantang River, can also reduce the supply of water resources. 4) The quick growth of urban population, excessive aquaculture, and ineffective government supervision played an important social role in the process of this event. In the all, this extreme water shortage event was the result of both natural and social factors. This research is very helpful for the futuristic water resource forecast in Yangtze River Delta, and it also affords us lessons on the risk management and heritage conservation that merit attention. Key Words: Hangzhou, 1247 AD, water shortage, canal, West Lake, natural factors, social factors

  19. Active background suppression with the liquid argon scintillation veto of GERDA Phase II

    NASA Astrophysics Data System (ADS)

    Agostini, M.; Allardt, M.; Bakalyarov, A. M.; Balata, M.; Barabanov, I.; Baudis, L.; Bauer, C.; Bellotti, E.; Belogurov, S.; Belyaev, S. T.; Benato, G.; Bettini, A.; Bezrukov, L.; Bode, T.; Borowicz, D.; Brudanin, V.; Brugnera, R.; Caldwell, A.; Cattadori, C.; Chernogorov, A.; D'Andrea, V.; Demidova, E. V.; Di Marco, N.; Domula, A.; Doroshkevich, E.; Egorov, V.; Falkenstein, R.; Frodyma, N.; Gangapshev, A.; Garfagnini, A.; Gooch, C.; Grabmayr, P.; Gurentsov, V.; Gusev, K.; Hakenmüller, J.; Hegai, A.; Heisel, M.; Hemmer, S.; Hofmann, W.; Hult, M.; Inzhechik, L. V.; Janicskó Csáthy, J.; Jochum, J.; Junker, M.; Kazalov, V.; Kihm, T.; Kirpichnikov, I. V.; Kirsch, A.; Kish, A.; Klimenko, A.; Kneißl, R.; Knöpfle, K. T.; Kochetov, O.; Kornoukhov, V. N.; Kuzminov, V. V.; Laubenstein, M.; Lazzaro, A.; Lebedev, V. I.; Lehnert, B.; Liao, H. Y.; Lindner, M.; Lippi, I.; Lubashevskiy, A.; Lubsandorzhiev, B.; Lutter, G.; Macolino, C.; Majorovits, B.; Maneschg, W.; Medinaceli, E.; Miloradovic, M.; Mingazheva, R.; Misiaszek, M.; Moseev, P.; Nemchenok, I.; Palioselitis, D.; Panas, K.; Pandola, L.; Pelczar, K.; Pullia, A.; Riboldi, S.; Rumyantseva, N.; Sada, C.; Salamida, F.; Salathe, M.; Schmitt, C.; Schneider, B.; Schönert, S.; Schreiner, J.; Schulz, O.; Schütz, A.-K.; Schwingenheuer, B.; Selivanenko, O.; Shevzik, E.; Shirchenko, M.; Simgen, H.; Smolnikov, A.; Stanco, L.; Vanhoefer, L.; Vasenko, A. A.; Veresnikova, A.; von Sturm, K.; Wagner, V.; Wegmann, A.; Wester, T.; Wiesinger, C.; Wojcik, M.; Yanovich, E.; Zhitnikov, I.; Zhukov, S. V.; Zinatulina, D.; Zuber, K.; Zuzel, G.

    2017-09-01

    The observation of neutrinoless double beta decay would allow to shed light onto the particle nature of neutrinos. Gerda is aiming to perform a background-free search for this process using high purity germanium detectors enriched in 76Ge operated in liquid argon. This goal relies on the application of active background suppression techniques. A low background light instrumentation has been installed for Phase II to detect events with coincident energy deposition in the nearby liquid argon. The intended background index of ˜10-3 cts/(keV·ky·yr) has been confirmed.

  20. Optical polarization: background and camouflage

    NASA Astrophysics Data System (ADS)

    Škerlind, Christina; Hallberg, Tomas; Eriksson, Johan; Kariis, Hans; Bergström, David

    2017-10-01

    Polarimetric imaging sensors in the electro-optical region, already military and commercially available in both the visual and infrared, show enhanced capabilities for advanced target detection and recognition. The capabilities arise due to the ability to discriminate between man-made and natural background surfaces using the polarization information of light. In the development of materials for signature management in the visible and infrared wavelength regions, different criteria need to be met to fulfil the requirements for a good camouflage against modern sensors. In conventional camouflage design, the aimed design of the surface properties of an object is to spectrally match or adapt it to a background and thereby minimizing the contrast given by a specific threat sensor. Examples will be shown from measurements of some relevant materials and how they in different ways affect the polarimetric signature. Dimensioning properties relevant in an optical camouflage from a polarimetric perspective, such as degree of polarization, the viewing or incident angle, and amount of diffuse reflection, mainly in the infrared region, will be discussed.

  1. Meta-analysis of the association between appendiceal orifice inflammation and appendectomy and ulcerative colitis.

    PubMed

    Deng, Peng; Wu, Junchao

    2016-07-01

    This study aimed to investigate the relationship between appendiceal orifice inflammation (AOI) and appendectomy and ulcerative colitis (UC) by a meta-analysis. Databases were thoroughly searched for studies on AOI and UC up to January 2016. Three comparisons were performed: a) whether the previous appendectomy was a risk factor of UC; b) influence of appendectomy on UC courses; c) influence of AOI on UC severity. Odds ratios (ORs) and 95% confidence intervals (CIs) were the effects sizes. The merging of results and publication bias assessment were performed by using RevMan 5.3. Sensitivity analysis was conducted using Stata 12.0. Nineteen studies were selected in the present study. Results of comparison I showed that appendectomy was a protective factor of UC (OR = 0.44; 95% CI [0.30, 0.64]). Comparison II indicated appendectomy had no significant influence in the courses of UC (proctitis: OR = 1.03, 95% CI [0.74, 1.42]; left-sided colitis: OR = 1.01, 95% CI [0.73, 1.39]; pancolitis: OR = 0.92, 95% CI [0.59, 1.43]; colectomy: OR = 1.38, 95% CI [0.62, 3.04]). Comparison III indicated UC combined with AOI did not affect the courses of UC (proctitis: OR = 1.15, 95% CI [0.67, 1.98]; left-sided colitis: OR = 1.14, 95% CI [0.24, 5.42]; colectomy: OR = 0.36, 95% CI [0.10, 1.23]). Sensitivity analysis confirmed the robust of the results in the present study. In conclusion, this meta-analysis indicated appendectomy can reduce the risk of UC. But appendectomy or AOI had no influence on the severity of the disease and the effect of surgical treatment.

  2. Natural orifice transluminal endoscopic surgery for patients with perforated peptic ulcer.

    PubMed

    Bonin, Eduardo A; Moran, Erica; Gostout, Christopher J; McConico, Andrea L; Zielinski, Martin; Bingener, Juliane

    2012-06-01

    Perforation accounts for 70% of deaths attributed to peptic ulcers. Laparoscopic repair is effective but infrequently used. Our aim was to assess how many patients with perforated peptic ulcer could be candidates for a transluminal endoscopic omental patch closure. This retrospective study reviewed patients with perforated peptic ulcer from 2005 to 2010. Demographics, ulcer characteristics, operative procedure, and outcomes were recorded. Candidates for endoscopic transluminal repair were defined as those having undergone omental patch closure of an ulcer of appropriate size and no contraindications to laparoscopy or endoscopy. In the retrospective review, a total of 104 patients were identified; 62% female, mean age = 68 years, mean ASA of 3, and 63% medication-related ulcers. Fifty-nine (63%) had an omental patch (80% open), and 35 (37%) had other procedures. Ten patients had nonoperative management. Thirty-day mortality was 14% and 1 year mortality was 35%. Forty-nine patients (52%) were considered potential candidates for transluminal repair. Sixty-three percent of our patients sustained a medication-related perforation with 1 year mortality of 35%. The majority of patients were treated using open omental patch repair. Transluminal endoscopic repair may provide an additional situation for a minimally invasive approach for a number of these patients.

  3. Probing cluster potentials through gravitational lensing of background X-ray sources

    NASA Technical Reports Server (NTRS)

    Refregier, A.; Loeb, A.

    1996-01-01

    The gravitational lensing effect of a foreground galaxy cluster, on the number count statistics of background X-ray sources, was examined. The lensing produces a deficit in the number of resolved sources in a ring close to the critical radius of the cluster. The cluster lens can be used as a natural telescope to study the faint end of the (log N)-(log S) relation for the sources which account for the X-ray background.

  4. A method for simulating the release of natural gas from the rupture of high-pressure pipelines in any terrain.

    PubMed

    Deng, Yajun; Hu, Hongbing; Yu, Bo; Sun, Dongliang; Hou, Lei; Liang, Yongtu

    2018-01-15

    The rupture of a high-pressure natural gas pipeline can pose a serious threat to human life and environment. In this research, a method has been proposed to simulate the release of natural gas from the rupture of high-pressure pipelines in any terrain. The process of gas releases from the rupture of a high-pressure pipeline is divided into three stages, namely the discharge, jet, and dispersion stages. Firstly, a discharge model is established to calculate the release rate of the orifice. Secondly, an improved jet model is proposed to obtain the parameters of the pseudo source. Thirdly, a fast-modeling method applicable to any terrain is introduced. Finally, based upon these three steps, a dispersion model, which can take any terrain into account, is established. Then, the dispersion scenarios of released gas in four different terrains are studied. Moreover, the effects of pipeline pressure, pipeline diameter, wind speed and concentration of hydrogen sulfide on the dispersion scenario in real terrain are systematically analyzed. The results provide significant guidance for risk assessment and contingency planning of a ruptured natural gas pipeline. Copyright © 2017. Published by Elsevier B.V.

  5. Dolphins Adjust Species-Specific Frequency Parameters to Compensate for Increasing Background Noise

    PubMed Central

    Papale, Elena; Gamba, Marco; Perez-Gil, Monica; Martin, Vidal Martel; Giacoma, Cristina

    2015-01-01

    An increase in ocean noise levels could interfere with acoustic communication of marine mammals. In this study we explored the effects of anthropogenic and natural noise on the acoustic properties of a dolphin communication signal, the whistle. A towed array with four elements was used to record environmental background noise and whistles of short-beaked common-, Atlantic spotted- and striped-dolphins in the Canaries archipelago. Four frequency parameters were measured from each whistle, while Sound Pressure Levels (SPL) of the background noise were measured at the central frequencies of seven one-third octave bands, from 5 to 20 kHz. Results show that dolphins increase the whistles’ frequency parameters with lower variability in the presence of anthropogenic noise, and increase the end frequency of their whistles when confronted with increasing natural noise. This study provides the first evidence that the synergy among SPLs has a role in shaping the whistles' structure of these three species, with respect to both natural and anthropogenic noise. PMID:25853825

  6. Characterization of 176Lu background in LSO-based PET scanners

    NASA Astrophysics Data System (ADS)

    Conti, Maurizio; Eriksson, Lars; Rothfuss, Harold; Sjoeholm, Therese; Townsend, David; Rosenqvist, Göran; Carlier, Thomas

    2017-05-01

    LSO and LYSO are today the most common scintillators used in positron emission tomography. Lutetium contains traces of 176Lu, a radioactive isotope that decays β - with a cascade of γ photons in coincidence. Therefore, Lutetium-based scintillators are characterized by a small natural radiation background. In this paper, we investigate and characterize the 176Lu radiation background via experiments performed on LSO-based PET scanners. LSO background was measured at different energy windows and different time coincidence windows, and by using shields to alter the original spectrum. The effect of radiation background in particularly count-starved applications, such as 90Y imaging, is analysed and discussed. Depending on the size of the PET scanner, between 500 and 1000 total random counts per second and between 3 and 5 total true coincidences per second were measured in standard coincidence mode. The LSO background counts in a Siemens mCT in the standard PET energy and time windows are in general negligible in terms of trues, and are comparable to that measured in a BGO scanner of similar size.

  7. Antimony in recent, ombrotrophic peat from Switzerland and Scotland: Comparison with natural background values (5,320 to 8,020 14C yr BP) and implications for the global atmospheric Sb cycle

    NASA Astrophysics Data System (ADS)

    Shotyk, William; Krachler, Michael; Chen, Bin

    2004-03-01

    The lowest concentrations, atmospheric fluxes, and enrichments of Sb in a Swiss bog were found in peat samples dating from 8,020 to 5,320 14C yr BP when Sb inputs were proportional to those of Sc and effectively controlled by deposition of soil dust. For comparison with these ancient samples, modern peat samples from five rural areas of Switzerland and two remote areas of Scotland and Shetland are highly contaminated with Sb, with enrichments of the order of 30 to 80 times. "Lithogenic" Sb concentrations calculated using the Sc concentrations and background Sb/Sc ratio are dwarfed at all sites by "anthropogenic" Sb. The chronology and intensity of the Sb enrichments are in many ways similar to those of Pb which indicates that (1) Sb, like Pb, is well preserved in ombrotrophic peat and (2) the extent of human impacts on the geochemical cycle of Sb is comparable to that of Pb. The similar distribution of Sb and Pb can be explained in terms of their chemical and mineralogical associations, with most lead minerals being rich in Sb. Assuming that the "background" Sb flux (0.35 μg/m2/yr) from the Swiss bog is representative of preanthropogenic deposition rates worldwide, the global flux of natural Sb is estimated at 154 T/a. Using the natural Pb flux published by [1987] of 2600 T/a and the "background" Pb/Sb ratio (29) of the preanthropogenic peat samples, the global flux of natural Sb is estimated at 90 T/a. Either way, these values (90 to 154 T/a) are considerably lower than the current estimate of natural Sb to the global atmosphere (2400 T/a) published by [2001]. Assuming that the current estimate of anthropogenic Sb to the global atmosphere (1600 T/a) is correct [, 2001], the ratio of anthropogenic to natural Sb emissions is on the order of 10 to 18. Taken together, the data from modern and ancient peat samples suggests that the impact of human activities on the global geochemical cycle of Sb may have been underestimated by an order of magnitude. Like Pb, Sb has no

  8. 3D Inversion of Natural Source Electromagnetics

    NASA Astrophysics Data System (ADS)

    Holtham, E. M.; Oldenburg, D. W.

    2010-12-01

    The superior depth of investigation of natural source electromagnetic techniques makes these methods excellent candidates for crustal studies as well as for mining and hydrocarbon exploration. The traditional natural source method, the magnetotelluric (MT) technique, has practical limitations because the surveys are costly and time consuming due to the labor intensive nature of ground based surveys. In an effort to continue to use the penetration advantage of natural sources, it has long been recognized that tipper data, the ratio of the local vertical magnetic field to the horizontal magnetic field, provide information about 3D electrical conductivity structure. It was this understanding that prompted the development of AFMAG (Audio Frequency Magnetics) and recently the new airborne Z-Axis Tipper Electromagnetic Technique (ZTEM). In ZTEM, the vertical component of the magnetic field is recorded above the entire survey area, while the horizontal fields are recorded at a ground-based reference station. MT processing techniques yield frequency domain transfer functions typically between 30-720 Hz that relate the vertical fields over the survey area to the horizontal fields at the reference station. The result is a cost effective procedure for collecting natural source EM data and for finding large scale targets at moderate depths. It is well known however that 1D layered structures produce zero vertical magnetic fields and thus ZTEM data cannot recover such background conductivities. This is in sharp contrast to the MT technique where electric fields are measured and a 1D background conductivity can be recovered from the off diagonal elements of the impedance tensor. While 1D models produce no vertical fields, two and three dimensional structures will produce anomalous currents and a ZTEM response. For such models the background conductivity structure does affect the data. In general however, the ZTEM data have weak sensitivity to the background conductivity and

  9. Low-background germanium radioassay for the MAJORANA Collaboration

    NASA Astrophysics Data System (ADS)

    Trimble, James E., Jr.

    The focus of the MAJORANA COLLABORATION is the search for nuclear neutrinoless double beta decay. If discovered, this process would prove that the neutrino is its own anti-particle, or a M AJORANA particle. Being constructed at the Sanford Underground Research Facility, the MAJORANA DEMONSTRATOR aims to show that a background rate of 3 counts per region of interest (ROI) per tonne per year in the 4 keV ROI surrounding the 2039-keV Q-value energy of 76Ge is achievable and to demonstrate the technological feasibility of building a tonne-scale Ge-based experiment. Because of the rare nature of this process, detectors in the system must be isolated from ionizing radiation backgrounds as much as possible. This involved building the system with materials containing very low levels of naturally- occurring and anthropogenic radioactive isotopes at a deep underground site. In order to measure the levels of radioactive contamination in some components, the Majorana Demonstrator uses a low background counting facility managed by the Experimental Nuclear and Astroparticle Physics (ENAP) group at UNC. The UNC low background counting (LBC) facility is located at the Kimballton Underground Research Facility (KURF) located in Ripplemead, VA. The facility was used for a neutron activation analysis of samples of polytetrafluoroethylene (PTFE) and fluorinated ethylene propylene (FEP) tubing intended for use in the Demonstrator. Calculated initial activity limits (90% C.L.) of 238U and 232Th in the 0.002-in PTFE samples were 7.6 ppt and 5.1 ppt, respectively. The same limits in the FEP tubing sample were 150 ppt and 45 ppt, respectively. The UNC LBC was also used to gamma-assay a modified stainless steel flange to be used as a vacuum feedthrough. Trace activities of both 238U and 232Th were found in the sample, but all were orders of magnitude below the acceptable threshold for the Majorana experiment. Also discussed is a proposed next generation ultra-low background system designed

  10. Transjejunal Extraction of Gallbladder After Mini-Laparoscopic Cholecystectomy in Patients with Previous Roux-en-Y Gastric Bypass: A Small Case Series.

    PubMed

    Kayaalp, Cuneyt; Tardu, Ali; Yagci, Mehmet Ali; Sumer, Fatih

    2015-07-01

    The length of incisions on the abdominal wall directly correlates with wound-related morbidities and patient comfort. Both mini-laparoscopy (only ≤5-mm trocars) and natural orifice specimen extraction avoid larger abdominal incisions. This study described a new natural orifice translumenal endoscopic surgery (NOTES(®); American Society for Gastrointestinal Endoscopy [Oak Brook, IL] and Society of American Gastrointestinal and Endoscopic Surgeons [Los Angeles, CA]) cholecystectomy technique by combination of these two advanced laparoscopic techniques for cholelithiasis in patients who had prior laparoscopic Roux-en-Y gastric bypass (LRYGB) for obesity. Three patients (two males, one female; 39, 62, and 34 years old, respectively) were admitted with symptomatic cholelithiasis (multiple millimeter-sized gallstones), and all had previously had LRYGB. They were treated by mini-laparoscopic cholecystectomy using three 5-mm trocars. The gallbladder was removed through the dilated efferent limb of the jejunum, 5 cm distal from the gastrojejunostomy. Transjejunal extraction was performed under endoscopic guidance. The gallbladder in the jejenum was passed through the anastomosis and extracted with an endoscopic snare by the transoral way. The enterotomy was closed intracorporeally. There was no conversion or additional trocar requirement. All the procedures were completed successfully without problems. Respective operating times were 95, 75, and 120 minutes. Only 1 patient required postoperative analgesic; the others did not. The patients started to get a liquid diet on the night of surgery and were discharged on Days 1, 1, and 2, respectively, with normal diet recommendations. There were no morbidities. Mini-laparoscopic cholecystectomy is technically feasible in patients with previous LRYGB. Prior LRYGB was not an obstacle for transoral specimen extraction. The dilated efferent jejunal limb is a good alternative route for natural orifice specimen extraction. This

  11. Euro-NOTES Status Paper: from the concept to clinical practice.

    PubMed

    Fuchs, K H; Meining, A; von Renteln, D; Fernandez-Esparrach, G; Breithaupt, W; Zornig, C; Lacy, A

    2013-05-01

    The concept of natural orifice transluminal endoscopic surgery (NOTES) consists of the reduction of access trauma by using a natural orifice access to the intra-abdominal cavity. This could possibly lead to less postoperative pain, quicker recovery from surgery, fewer postoperative complications, fewer wound infections, and fewer long-term problems such as hernias. The Euro-NOTES Foundation has organized yearly meetings to work on this concept to bring it safely into clinical practice. The aim of this Euro-NOTES status update is to assess the yearly scientific working group reports and provide an overview on the current clinical practice of NOTES procedures. After the Euro-NOTES meeting 2011 in Frankfurt, Germany, an analysis was started regarding the most important topics of the European working groups. All prospectively documented information was gathered from Euro-NOTES and D-NOTES working groups from 2007 to 2011. The top five topics were analyzed. The statements of the working group activities demonstrate the growing information and changing insights. The most important selected topics were infection issue, peritoneal access, education and training, platforms and new technology, closure, suture, and anastomosis. The focus on research topics changed over time. The principle of hybrid access has overcome the technical and safety limitations of pure NOTES. Currently the following NOTES access routes are established for several indications: transvaginal access for cholecystectomy, appendectomy and colon resections; transesophageal access for myotomy; transgastric access for full-thickness small-tumor resections; and transanal/transcolonic access for rectal and colon resections. NOTES and hybrid NOTES techniques have emerged for all natural orifices and were introduced into clinical practice with a good safety record. There are different indications for different natural orifices. Each technique has been optimized for the purpose of finding a safe and realistic

  12. LArGe: active background suppression using argon scintillation for the Gerda 0ν β β -experiment

    NASA Astrophysics Data System (ADS)

    Agostini, M.; Barnabé-Heider, M.; Budjáš, D.; Cattadori, C.; Gangapshev, A.; Gusev, K.; Heisel, M.; Junker, M.; Klimenko, A.; Lubashevskiy, A.; Pelczar, K.; Schönert, S.; Smolnikov, A.; Zuzel, G.

    2015-10-01

    LArGe is a Gerda low-background test facility to study novel background suppression methods in a low-background environment, for future application in the Gerda experiment. Similar to Gerda, LArGe operates bare germanium detectors submersed into liquid argon (1 m^3, 1.4 tons), which in addition is instrumented with photomultipliers to detect argon scintillation light. The scintillation signals are used in anti-coincidence with the germanium detectors to effectively suppress background events that deposit energy in the liquid argon. The background suppression efficiency was studied in combination with a pulse shape discrimination (PSD) technique using a BEGe detector for various sources, which represent characteristic backgrounds to Gerda. Suppression factors of a few times 10^3 have been achieved. First background data of LArGe with a coaxial HPGe detector (without PSD) yield a background index of (0.12-4.6)× 10^{-2} cts/(keV kg year) (90 % C.L.), which is at the level of Gerda Phase I. Furthermore, for the first time we monitor the natural ^{42}Ar abundance (parallel to Gerda), and have indication for the 2ν β β -decay in natural germanium. These results show the effectivity of an active liquid argon veto in an ultra-low background environment. As a consequence, the implementation of a liquid argon veto in Gerda Phase II is pursued.

  13. A unidirectional acoustic cloak for multilayered background media with homogeneous metamaterials

    NASA Astrophysics Data System (ADS)

    Zhu, Jian; Chen, Tianning; Liang, Qingxuan; Wang, Xiaopeng; Xiong, Jie; Jiang, Ping

    2015-08-01

    The acoustic cloak, which can make an object hard to detect acoustically in a homogeneous background, has attracted great attention from researchers in recent years. The inhomogeneous background media were considered in this paper. The relative constitutive parameters were derived for acoustic cloaks working in multilayered media. And a unidirectional acoustic cloak for layered background media was proposed, designed and implemented successfully in a wide frequency range. In water and NaCl aqueous solution, the acoustic cloak was designed and realized with homogeneous metamaterials which were composed of steel and porous materials. The effective parameters of the unit cells of the cloak were determined by using the effective medium theory. Numerical results demonstrated excellent cloaking performance and showed that such a device could be physically realized with natural materials which will greatly promote the real applications of an invisibility cloak in inhomogeneous backgrounds.

  14. Estimating natural background groundwater chemistry, Questa molybdenum mine, New Mexico

    USGS Publications Warehouse

    Verplanck, Phillip L.; Nordstrom, D. Kirk; Plumlee, Geoffrey S.; Walker, Bruce M.; Morgan, Lisa A.; Quane, Steven L.

    2010-01-01

    This 2 1/2 day field trip will present an overview of a U.S. Geological Survey (USGS) project whose objective was to estimate pre-mining groundwater chemistry at the Questa molybdenum mine, New Mexico. Because of intense debate among stakeholders regarding pre-mining groundwater chemistry standards, the New Mexico Environment Department and Chevron Mining Inc. (formerly Molycorp) agreed that the USGS should determine pre-mining groundwater quality at the site. In 2001, the USGS began a 5-year, multidisciplinary investigation to estimate pre-mining groundwater chemistry utilizing a detailed assessment of a proximal natural analog site and applied an interdisciplinary approach to infer pre-mining conditions. The trip will include a surface tour of the Questa mine and key locations in the erosion scar areas and along the Red River. The trip will provide participants with a detailed understanding of geochemical processes that influence pre-mining environmental baselines in mineralized areas and estimation techniques for determining pre-mining baseline conditions.

  15. Estimating background and threshold nitrate concentrations using probability graphs

    USGS Publications Warehouse

    Panno, S.V.; Kelly, W.R.; Martinsek, A.T.; Hackley, Keith C.

    2006-01-01

    Because of the ubiquitous nature of anthropogenic nitrate (NO 3-) in many parts of the world, determining background concentrations of NO3- in shallow ground water from natural sources is probably impossible in most environments. Present-day background must now include diffuse sources of NO3- such as disruption of soils and oxidation of organic matter, and atmospheric inputs from products of combustion and evaporation of ammonia from fertilizer and livestock waste. Anomalies can be defined as NO3- derived from nitrogen (N) inputs to the environment from anthropogenic activities, including synthetic fertilizers, livestock waste, and septic effluent. Cumulative probability graphs were used to identify threshold concentrations separating background and anomalous NO3-N concentrations and to assist in the determination of sources of N contamination for 232 spring water samples and 200 well water samples from karst aquifers. Thresholds were 0.4, 2.5, and 6.7 mg/L for spring water samples, and 0.1, 2.1, and 17 mg/L for well water samples. The 0.4 and 0.1 mg/L values are assumed to represent thresholds for present-day precipitation. Thresholds at 2.5 and 2.1 mg/L are interpreted to represent present-day background concentrations of NO3-N. The population of spring water samples with concentrations between 2.5 and 6.7 mg/L represents an amalgam of all sources of NO3- in the ground water basins that feed each spring; concentrations >6.7 mg/L were typically samples collected soon after springtime application of synthetic fertilizer. The 17 mg/L threshold (adjusted to 15 mg/L) for well water samples is interpreted as the level above which livestock wastes dominate the N sources. Copyright ?? 2006 The Author(s).

  16. Stop the top background of the stop search

    NASA Astrophysics Data System (ADS)

    Bai, Yang; Cheng, Hsin-Chia; Gallicchio, Jason; Gu, Jiayin

    2012-07-01

    The main background for the supersymmetric stop direct production search comes from Standard Model toverline t events. For the single-lepton search channel, we introduce a few kinematic variables to further suppress this background by focusing on its dileptonic and semileptonic topologies. All are defined to have end points in the background, but not signal distributions. They can substantially improve the stop signal significance and mass reach when combined with traditional kinematic variables such as the total missing transverse energy. Among them, our variable M_{{T2}}^W hasthebestoverallperformancebecause it uses all available kinematic information, including the on-shell mass of both W's. We see 20 %-30 % improvement on the discovery significance and estimate that the 8 TeV LHC run with 20 fb-1 of data would be able to reach an exclusion limit of 650-700 GeV for direct stop production, as long as the stop decays dominantly to the top quark and a light stable neutralino. Most of the mass range required for the supersymmetric solution of the naturalness problem in the standard scenario can be covered.

  17. Comparison of Code Predictions to Test Measurements for Two Orifice Compensated Hydrostatic Bearings at High Reynolds Numbers

    NASA Technical Reports Server (NTRS)

    Keba, John E.

    1996-01-01

    Rotordynamic coefficients obtained from testing two different hydrostatic bearings are compared to values predicted by two different computer programs. The first set of test data is from a relatively long (L/D=1) orifice compensated hydrostatic bearing tested in water by Texas A&M University (TAMU Bearing No.9). The second bearing is a shorter (L/D=.37) bearing and was tested in a lower viscosity fluid by Rocketdyne Division of Rockwell (Rocketdyne 'Generic' Bearing) at similar rotating speeds and pressures. Computed predictions of bearing rotordynamic coefficients were obtained from the cylindrical seal code 'ICYL', one of the industrial seal codes developed for NASA-LeRC by Mechanical Technology Inc., and from the hydrodynamic bearing code 'HYDROPAD'. The comparison highlights the difference the bearing has on the accuracy of the predictions. The TAMU Bearing No. 9 test data is closely matched by the predictions obtained for the HYDROPAD code (except for added mass terms) whereas significant differences exist between the data from the Rocketdyne 'Generic' bearing the code predictions. The results suggest that some aspects of the fluid behavior in the shorter, higher Reynolds Number 'Generic' bearing may not be modeled accurately in the codes. The ICYL code predictions for flowrate and direct stiffness approximately equal those of HYDROPAD. Significant differences in cross-coupled stiffness and the damping terms were obtained relative to HYDROPAD and both sets of test data. Several observations are included concerning application of the ICYL code.

  18. Continuous separation of breast cancer cells from blood samples using multi-orifice flow fractionation (MOFF) and dielectrophoresis (DEP).

    PubMed

    Moon, Hui-Sung; Kwon, Kiho; Kim, Seung-Il; Han, Hyunju; Sohn, Joohyuk; Lee, Soohyeon; Jung, Hyo-Il

    2011-03-21

    Circulating tumor cells (CTCs) are highly correlated with the invasive behavior of cancer, so their isolations and quantifications are important for biomedical applications such as cancer prognosis and measuring the responses to drug treatments. In this paper, we present the development of a microfluidic device for the separation of CTCs from blood cells based on the physical properties of cells. For use as a CTC model, we successfully separated human breast cancer cells (MCF-7) from a spiked blood cell sample by combining multi-orifice flow fractionation (MOFF) and dielectrophoretic (DEP) cell separation technique. Hydrodynamic separation takes advantage of the massive and high-throughput filtration of blood cells as it can accommodate a very high flow rate. DEP separation plays a role in precise post-processing to enhance the efficiency of the separation. The serial combination of these two different sorting techniques enabled high-speed continuous flow-through separation without labeling. We observed up to a 162-fold increase in MCF-7 cells at a 126 µL min(-1) flow rate. Red and white blood cells were efficiently removed with separation efficiencies of 99.24% and 94.23% respectively. Therefore, we suggest that our system could be used for separation and detection of CTCs from blood cells for biomedical applications. This journal is © The Royal Society of Chemistry 2011

  19. Radiation dose in the high background radiation area in Kerala, India.

    PubMed

    Christa, E P; Jojo, P J; Vaidyan, V K; Anilkumar, S; Eappen, K P

    2012-03-01

    A systematic radiological survey has been carried out in the region of high-background radiation area in Kollam district of Kerala to define the natural gamma-radiation levels. One hundred and forty seven soil samples from high-background radiation areas and five samples from normal background region were collected as per standard sampling procedures and were analysed for (238)U, (232)Th and (40)K by gamma-ray spectroscopy. External gamma dose rates at all sampling locations were also measured using a survey meter. The activities of (238)U, (232)Th and (40)K was found to vary from 17 to 3081 Bq kg(-1), 54 to 11976 Bq kg(-1) and BDL (67.4 Bq kg(-1)) to 216 Bq kg(-1), respectively, in the study area. Such heterogeneous distribution of radionuclides in the region may be attributed to the deposition phenomenon of beach sand soil in the region. Radium equivalent activities were found high in several locations. External gamma dose rates estimated from the levels of radionuclides in soil had a range from 49 to 9244 nGy h(-1). The result of gamma dose rate measured at the sampling sites using survey meter showed an excellent correlation with dose rates computed from the natural radionuclides estimated from the soil samples.

  20. Background noise cancellation for improved acoustic detection of manatee vocalizations

    NASA Astrophysics Data System (ADS)

    Yan, Zheng; Niezrecki, Christopher; Beusse, Diedrich O.

    2005-06-01

    The West Indian manatee (Trichechus manatus latirostris) has become endangered partly because of an increase in the number of collisions with boats. A device to alert boaters of the presence of manatees, so that a collision can be avoided, is desired. A practical implementation of the technology is dependent on the hydrophone spacing and range of detection. These parameters are primarily dependent on the manatee vocalization strength, the decay of the signal's strength with distance, and the background noise levels. An efficient method to extend the detection range by using background noise cancellation is proposed in this paper. An adaptive line enhancer (ALE) that can detect and track narrow band signals buried in broadband noise is implemented to cancel the background noise. The results indicate that the ALE algorithm can efficiently extract the manatee calls from the background noise. The improved signal-to-noise ratio of the signal can be used to extend the range of detection of manatee vocalizations and reduce the false alarm and missing detection rate in their natural habitat. .

  1. Background noise cancellation for improved acoustic detection of manatee vocalizations

    NASA Astrophysics Data System (ADS)

    Yan, Zheng; Niezrecki, Christopher; Beusse, Diedrich O.

    2005-04-01

    The West Indian manatee (Trichechus manatus latirostris) has become endangered partly because of an increase in the number of collisions with boats. A device to alert boaters of the presence of manatees, so that a collision can be avoided, is desired. Practical implementation of the technology is dependent on the hydrophone spacing and range of detection. These parameters are primarily dependent on the manatee vocalization strength, the decay of the signal strength with distance, and the background noise levels. An efficient method to extend the detection range by using background noise cancellation is proposed in this paper. An adaptive line enhancer (ALE) that can detect and track narrowband signals buried in broadband noise is implemented to cancel the background noise. The results indicate that the ALE algorithm can efficiently extract the manatee calls from the background noise. The improved signal-to-noise ratio of the signal can be used to extend the range of detection of manatee vocalizations and reduce the false alarm and missing detection rate in their natural habitat.

  2. Background noise model development for seismic stations of KMA

    NASA Astrophysics Data System (ADS)

    Jeon, Youngsoo

    2010-05-01

    The background noise recorded at seismometer is exist at any seismic signal due to the natural phenomena of the medium which the signal passed through. Reducing the seismic noise is very important to improve the data quality in seismic studies. But, the most important aspect of reducing seismic noise is to find the appropriate place before installing the seismometer. For this reason, NIMR(National Institution of Meteorological Researches) starts to develop a model of standard background noise for the broadband seismic stations of the KMA(Korea Meteorological Administration) using a continuous data set obtained from 13 broadband stations during the period of 2007 and 2008. We also developed the model using short period seismic data from 10 stations at the year of 2009. The method of Mcmara and Buland(2004) is applied to analyse background noise of Korean Peninsula. The fact that borehole seismometer records show low noise level at frequency range greater than 1 Hz compared with that of records at the surface indicate that the cultural noise of inland Korean Peninsula should be considered to process the seismic data set. Reducing Double Frequency peak also should be regarded because the Korean Peninsula surrounded by the seas from eastern, western and southern part. The development of KMA background model shows that the Peterson model(1993) is not applicable to fit the background noise signal generated from Korean Peninsula.

  3. Czech Children's Drawing of Nature

    ERIC Educational Resources Information Center

    Yilmaz, Zuhal; Kubiatko, Milan; Topal, Hatice

    2012-01-01

    Do world children draw nature pictures in a certain way? Range of mountains in the background, a sun, couple clouds, a river rising from mountains. Is this type of drawing universal in the way these nature items are organized on a drawing paper? The sample size from Czech Republic included 33 participants from two kindergartens. They were 5 and 6…

  4. On the ghost-induced instability on de Sitter background

    NASA Astrophysics Data System (ADS)

    Peter, Patrick; Salles, Filipe de O.; Shapiro, Ilya L.

    2018-03-01

    It is known that the perturbative instability of tensor excitations in higher derivative gravity may not take place if the initial frequency of the gravitational waves is below the Planck threshold. One can assume that this is a natural requirement if the cosmological background is sufficiently mild, since in this case the situation is qualitatively close to the free gravitational wave in flat space. Here, we explore the opposite situation and consider the effect of a very far from Minkowski radiation-dominated or de Sitter cosmological background with a large Hubble rate, e.g., typical of an inflationary period. It turns out that, then, for initial Planckian or even trans-Planckian frequencies, the instability is rapidly suppressed by the very fast expansion of the Universe.

  5. Background characterization of an ultra-low background liquid scintillation counter

    DOE PAGES

    Erchinger, J. L.; Orrell, John L.; Aalseth, C. E.; ...

    2017-01-26

    The Ultra-Low Background Liquid Scintillation Counter developed by Pacific Northwest National Laboratory will expand the application of liquid scintillation counting by enabling lower detection limits and smaller sample volumes. By reducing the overall count rate of the background environment approximately 2 orders of magnitude below that of commercially available systems, backgrounds on the order of tens of counts per day over an energy range of ~3–3600 keV can be realized. Finally, initial test results of the ULB LSC show promising results for ultra-low background detection with liquid scintillation counting.

  6. Ambient Background Particulate Compositiion Outdoor Natural Background: Interferents/Clutter

    DTIC Science & Technology

    2011-08-01

    FIGURES 1. Map of UK Sampling Locations, Lizard, Pershore, Birmingham, Lichfield 10 2. Mean UK Airborne Pollen , Fungi, and Bacteria and/or their Sum...routinely other than for health effects. Allergy caused by pollen (>15 urn) and mold is monitored for health effects by National Allergy 9...occurrence. To achieve this, measurement of pollens , bacteria, and fungal spores and dust particulates were undertaken for weekly periods at four

  7. Outdoor (222)Rn-concentrations in Germany - part 1 - natural background.

    PubMed

    Kümmel, M; Dushe, C; Müller, S; Gehrcke, K

    2014-06-01

    To determine the natural radiation exposure due to outdoor radon ((222)Rn) and its short-lived decay products in Germany, the Federal Office for Radiation Protection (BfS) conducted a measuring programme over three years. The annual mean radon concentration at 1.5 m above ground level was measured with solid-state track etch detectors at 173 measuring points in an even grid with a grid length of approx. 50 km. Furthermore, annual mean values of the equilibrium-equivalent radon concentration (EEC) and the equilibrium factor were estimated on the basis of the activity concentrations of (214)Pb and (214)Bi measured at 27 stations of the German Meteorological Service (DWD). Our study yielded a spatial mean outdoor radon concentration for Germany of 9 ± 1 Bq m(-3) (median: 8 (-0.5/+1.0) Bq m(-3)), with regional means varying from 4.5 Bq m(-3) in Hamburg to 14 Bq m(-3) in Bavaria. The determined EEC are in a range from 1.4 to 11 Bq m(-3). Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. Using background knowledge for picture organization and retrieval

    NASA Astrophysics Data System (ADS)

    Quintana, Yuri

    1997-01-01

    A picture knowledge base management system is described that is used to represent, organize and retrieve pictures from a frame knowledge base. Experiments with human test subjects were conducted to obtain further descriptions of pictures from news magazines. These descriptions were used to represent the semantic content of pictures in frame representations. A conceptual clustering algorithm is described which organizes pictures not only on the observable features, but also on implicit properties derived from the frame representations. The algorithm uses inheritance reasoning to take into account background knowledge in the clustering. The algorithm creates clusters of pictures using a group similarity function that is based on the gestalt theory of picture perception. For each cluster created, a frame is generated which describes the semantic content of pictures in the cluster. Clustering and retrieval experiments were conducted with and without background knowledge. The paper shows how the use of background knowledge and semantic similarity heuristics improves the speed, precision, and recall of queries processed. The paper concludes with a discussion of how natural language processing of can be used to assist in the development of knowledge bases and the processing of user queries.

  9. Changes in the Arctic: Background and Issues for Congress

    DTIC Science & Technology

    2011-04-07

    resources and to address socioeconomic impacts of changing patterns in the use of natural resources. Changes in the Arctic: Background and Issues for...also increasingly being viewed by some observers as a potential emerging security issue. In varying degrees, the Arctic coastal states have...by the term. Policy discussions of the Arctic can employ varying definitions of the region, and readers should bear in mind that the definition used

  10. Natural background groundwater composition in the Azores archipelago (Portugal): a hydrogeochemical study and threshold value determination.

    PubMed

    Cruz, J V; Andrade, C

    2015-07-01

    Groundwater discharges were sampled in selected springs from São Miguel (Furnas and Fogo trachytic central volcanoes) and Santa Maria islands (Azores, Portugal), in order to characterize natural background levels (NBLs) and proceed to the determination of threshold values (TVs). Besides being a key issue in order to fully assess the anthropogenic pressures, NBLs are also instrumental to derive TVs, therefore complying with requirements from the European Union Groundwater Directive. The composition of groundwater corresponds mainly to low mineralized Na-HCO3 to Na-Cl water types, the latter dominant in Santa Maria island, with a decreasing order of Na>Ca>Mg>K and Cl>HCO3>SO4>NO3 for cations and anion respectively. The majority of the samples are slightly acid to slightly alkaline (pH range of 5.45-7.43), and the electrical conductivity range between 180 and 1458 μS/cm. Groundwater composition is controlled by two major drivers, addition of sea salts and dissolution of silicate minerals. Results shown that TVs established along the present study are in general in the lower rank when compared to the range of values proposed by the several EU member states, with the main exception of NO3, reflecting the impact of agriculture activities over water quality in the Azores, and lower than the national ones. The comparison between the estimated NBL and TV with values derived with another dataset from the Azores, usually higher, depicts the effect of a larger and diverse number of groundwater sources over calculations. On the other hand, all samples which show a contribution from volcanic/hydrothermal systems were excluded from the dataset, which explains why the derived NBLs and TVs are lower comparing to other active volcanic areas, which is also a conservative approach on a subject that has regulatory implications. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Decolorization of Acid Orange 7 by an electric field-assisted modified orifice plate hydrodynamic cavitation system: Optimization of operational parameters.

    PubMed

    Jung, Kyung-Won; Park, Dae-Seon; Hwang, Min-Jin; Ahn, Kyu-Hong

    2015-09-01

    In this study, the decolorization of Acid Orange 7 (AO-7) with intensified performance was obtained using hydrodynamic cavitation (HC) combined with an electric field (graphite electrodes). As a preliminary step, various HC systems were compared in terms of decolorization, and, among them, the electric field-assisted modified orifice plate HC (EFM-HC) system exhibited perfect decolorization performance within 40 min of reaction time. Interestingly, when H2O2 was injected into the EFM-HC system as an additional oxidant, the reactor performance gradually decreased as the dosing ratio increased; thus, the remaining experiments were performed without H2O2. Subsequently, an optimization process was conducted using response surface methodology with a Box-Behnken design. The inlet pressure, initial pH, applied voltage, and reaction time were chosen as operational key factors, while decolorization was selected as the response variable. The overall performance revealed that the selected parameters were either slightly interdependent, or had significant interactive effects on the decolorization. In the verification test, complete decolorization was observed under statistically optimized conditions. This study suggests that EFM-HC is a useful method for pretreatment of dye wastewater with positive economic and commercial benefits. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Changes in the Arctic: Background and Issues for Congress

    DTIC Science & Technology

    2010-10-15

    resources and to address socioeconomic impacts of changing patterns in the use of natural resources. Changes in the Arctic: Background and Issues for...by some observers as a potential emerging security issue. In varying degrees, the Arctic coastal states have indicated a willingness to establish and...varying definitions of the region, and readers should bear in mind that the definition used in one discussion may differ from that used in another. This

  13. Research on cloud background infrared radiation simulation based on fractal and statistical data

    NASA Astrophysics Data System (ADS)

    Liu, Xingrun; Xu, Qingshan; Li, Xia; Wu, Kaifeng; Dong, Yanbing

    2018-02-01

    Cloud is an important natural phenomenon, and its radiation causes serious interference to infrared detector. Based on fractal and statistical data, a method is proposed to realize cloud background simulation, and cloud infrared radiation data field is assigned using satellite radiation data of cloud. A cloud infrared radiation simulation model is established using matlab, and it can generate cloud background infrared images for different cloud types (low cloud, middle cloud, and high cloud) in different months, bands and sensor zenith angles.

  14. In Vitro Sealing Properties of Calcium-Enriched Mixture and Mineral Trioxide Aggregate Orifice Barriers during Intra-Coronal Bleaching

    PubMed Central

    Moghadam, Negar; Abdollahi, Amir Ardalan; Aghabalayi Fakhim, Hoda; Borna, Zahra

    2017-01-01

    Introduction: This study aimed at evaluating the sealing properties of calcium-enriched mixture (CEM) compared to mineral trioxide aggregate (MTA) as a cervical barriers in intra-coronal bleaching. Methods and Materials: In this in vitro study, endodontic treatment was performed on 60 extracted human incisors and canines without canal calcification, caries, restorations, resorption or cracks. The teeth were then randomly divided into two experimental groups and two control groups (n=15). Then, CEM cement and MTA were applied as 3-mm intra-orifice barriers in the test groups; a mixture of sodium perborate and 30% hydrogen peroxide bleaching agents were placed within the pulp chamber for one week. Dye penetration method was used to evaluate the sealing ability of agents. Statistical analysis was performed using SPSS software. The Kendall coefficient was used to evaluate inter-observer agreement. The chi-squared test was used for statistical analysis. Results: The results showed that the penetration rates of CEM and MTA were the same as positive control group, with no significant differences (P=0.673 and P=0.408, respectively). However, there was a significant difference between the negative control group and CEM and MTA groups (P=0.001 for both groups). In addition, the sealing ability of MTA and CEM cement were not significantly different (P=0.682). Conclusion: During intra-coronal bleaching procedures CEM cement can be used as a cervical barrier with sealing properties comparable to that of MTA. PMID:28512492

  15. In Vitro Sealing Properties of Calcium-Enriched Mixture and Mineral Trioxide Aggregate Orifice Barriers during Intra-Coronal Bleaching.

    PubMed

    Moghadam, Negar; Abdollahi, Amir Ardalan; Aghabalayi Fakhim, Hoda; Borna, Zahra

    2017-01-01

    This study aimed at evaluating the sealing properties of calcium-enriched mixture (CEM) compared to mineral trioxide aggregate (MTA) as a cervical barriers in intra-coronal bleaching. In this in vitro study, endodontic treatment was performed on 60 extracted human incisors and canines without canal calcification, caries, restorations, resorption or cracks. The teeth were then randomly divided into two experimental groups and two control groups ( n =15). Then, CEM cement and MTA were applied as 3-mm intra-orifice barriers in the test groups; a mixture of sodium perborate and 30% hydrogen peroxide bleaching agents were placed within the pulp chamber for one week. Dye penetration method was used to evaluate the sealing ability of agents. Statistical analysis was performed using SPSS software. The Kendall coefficient was used to evaluate inter-observer agreement. The chi-squared test was used for statistical analysis. The results showed that the penetration rates of CEM and MTA were the same as positive control group, with no significant differences ( P =0.673 and P =0.408, respectively). However, there was a significant difference between the negative control group and CEM and MTA groups ( P =0.001 for both groups). In addition, the sealing ability of MTA and CEM cement were not significantly different ( P =0.682). During intra-coronal bleaching procedures CEM cement can be used as a cervical barrier with sealing properties comparable to that of MTA.

  16. Metro nature, environmental health, and economic value

    Treesearch

    Kathleen L. Wolf; Alicia S.T. Robbins

    2015-01-01

    Background: Nearly 40 years of research provides an extensive body of evidence about human health, well-being, and improved function benefits associated with experiences of nearby nature in cities.Objectives: We demonstrate the numerous opportunities for future research efforts that link metro nature, human health and well-being outcomes,...

  17. Nature contact and human health: A research agenda

    Treesearch

    Howard Frumkin; Gregory N. Bratman; Sara Jo Breslow; Bobby Cochran; Peter H. Kahn Jr; Joshua J. Lawler; Phillip S. Levin; Pooja S. Tandon; Usha Varanasi; Kathleen L. Wolf; Spencer A. Wood

    2017-01-01

    BACKGROUND: At a time of increasing disconnectedness from nature, scientific interest in the potential health benefits of nature contact has grown. Research in recent decades has yielded substantial evidence, but large gaps remain in our understanding. OBJECTIVES: We propose a research...

  18. Characterisation of neutron-sensitive bubble detectors for application in the measurement of jet aircrew exposure to natural background radiation.

    PubMed

    Tume, P; Lewis, B J; Bennett, L G; Cousins, T

    1998-01-01

    A survey of the natural background dose equivalent received by Canadian Forces aircrew was conducted using neutron-sensitive bubble detectors (BDs) as the primary detection tool. Since this study was a new application for these detectors, the BD response to neutron dose equivalent (RD) was extended from thermal to 500 MeV in neutron energy. Based upon the extended RD, it was shown that the manufacturer's calibration can be scaled by 1.5 +/- 0.5 to give a BD sensitivity that takes into account recently recommended fluence-to-neutron dose equivalent conversion functions and the cosmogenic neutron spectrum encountered at jet altitudes. An investigation of the effects of systematic bias caused by the cabin environment (i.e., temperature, pressure and relative humidity) on the in-flight measurements was also conducted. Both simulated and actual aircraft climate tests indicated that the detectors are insensitive to the pressure and relative humidity variations encountered during routine jet aircraft operations. Long term conditioning tests also confirmed that the BD-PND model of detector is sensitive to variations in temperature to within +/- 20%. As part of the testing process, the in-flight measurements also demonstrated that the neutron dose equivalent is distributed uniformly throughout a Boeing 707 jet aircraft, indicating that both pilots and flight attendants are exposed to the same neutron field intensity to within experimental uncertainty.

  19. Background sounds contribute to spectrotemporal plasticity in primary auditory cortex.

    PubMed

    Moucha, Raluca; Pandya, Pritesh K; Engineer, Navzer D; Rathbun, Daniel L; Kilgard, Michael P

    2005-05-01

    The mammalian auditory system evolved to extract meaningful information from complex acoustic environments. Spectrotemporal selectivity of auditory neurons provides a potential mechanism to represent natural sounds. Experience-dependent plasticity mechanisms can remodel the spectrotemporal selectivity of neurons in primary auditory cortex (A1). Electrical stimulation of the cholinergic nucleus basalis (NB) enables plasticity in A1 that parallels natural learning and is specific to acoustic features associated with NB activity. In this study, we used NB stimulation to explore how cortical networks reorganize after experience with frequency-modulated (FM) sweeps, and how background stimuli contribute to spectrotemporal plasticity in rat auditory cortex. Pairing an 8-4 kHz FM sweep with NB stimulation 300 times per day for 20 days decreased tone thresholds, frequency selectivity, and response latency of A1 neurons in the region of the tonotopic map activated by the sound. In an attempt to modify neuronal response properties across all of A1 the same NB activation was paired in a second group of rats with five downward FM sweeps, each spanning a different octave. No changes in FM selectivity or receptive field (RF) structure were observed when the neural activation was distributed across the cortical surface. However, the addition of unpaired background sweeps of different rates or direction was sufficient to alter RF characteristics across the tonotopic map in a third group of rats. These results extend earlier observations that cortical neurons can develop stimulus specific plasticity and indicate that background conditions can strongly influence cortical plasticity.

  20. Background sounds contribute to spectrotemporal plasticity in primary auditory cortex

    PubMed Central

    Moucha, Raluca; Pandya, Pritesh K.; Engineer, Navzer D.; Rathbun, Daniel L.

    2010-01-01

    The mammalian auditory system evolved to extract meaningful information from complex acoustic environments. Spectrotemporal selectivity of auditory neurons provides a potential mechanism to represent natural sounds. Experience-dependent plasticity mechanisms can remodel the spectrotemporal selectivity of neurons in primary auditory cortex (A1). Electrical stimulation of the cholinergic nucleus basalis (NB) enables plasticity in A1 that parallels natural learning and is specific to acoustic features associated with NB activity. In this study, we used NB stimulation to explore how cortical networks reorganize after experience with frequency-modulated (FM) sweeps, and how background stimuli contribute to spectrotemporal plasticity in rat auditory cortex. Pairing an 8–4 kHz FM sweep with NB stimulation 300 times per day for 20 days decreased tone thresholds, frequency selectivity, and response latency of A1 neurons in the region of the tonotopic map activated by the sound. In an attempt to modify neuronal response properties across all of A1 the same NB activation was paired in a second group of rats with five downward FM sweeps, each spanning a different octave. No changes in FM selectivity or receptive field (RF) structure were observed when the neural activation was distributed across the cortical surface. However, the addition of unpaired background sweeps of different rates or direction was sufficient to alter RF characteristics across the tonotopic map in a third group of rats. These results extend earlier observations that cortical neurons can develop stimulus specific plasticity and indicate that background conditions can strongly influence cortical plasticity PMID:15616812

  1. Nature of gamma rays background radiation in new and old buildings of Qatar University

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Al-Houty, L.; Abou-Leila, H.; El-Kameesy, S.

    Measurements and analysis of gamma-background radiation spectrum in four different places of Qatar University campus were performed at the energy range 10 keV-3 MeV using hyper pure Ge-detector. The dependence of the detector absolute photopeak efficiency on gamma-ray energies was determined and correction of the data for that was also done. The absorbed dose for each gamma line was calculated and an estimation of the total absorbed dose for the detected gamma lines in the four different places was obtained. Comparison with other results was also performed.

  2. The Nature of the Unresolved Extragalactic Cosmic Soft X-Ray Background

    NASA Technical Reports Server (NTRS)

    Cappelluti, N.; Ranalli, P.; Roncarelli, M.; Arevalo, P.; Zamorani, G.; Comastri, A.; Gilli, R.; Rovilos, E.; Vignali, C.; Allevato, V.; hide

    2013-01-01

    In this paper we investigate the power spectrum of the unresolved 0.5-2 keV cosmic X-ray background (CXB) with deep Chandra 4-Msec (Ms) observations in the Chandra Deep Field South (CDFS). We measured a signal that, on scales >30 arcsec, is significantly higher than the shot noise and is increasing with angular scale. We interpreted this signal as the joint contribution of clustered undetected sources like active galactic nuclei (AGN), galaxies and the intergalactic medium (IGM). The power of unresolved cosmic source fluctuations accounts for approximately 12 per cent of the 0.5-2 keV extragalactic CXB. Overall, our modelling predicts that approximately 20 per cent of the unresolved CXB flux is produced by low-luminosity AGN, approximately 25 per cent by galaxies and approximately 55 per cent by the IGM. We do not find any direct evidence of the so-called 'warm hot intergalactic medium' (i.e. matter with 10(exp 5) less than T less than 10(exp 7) K and density contrast delta less than 1000), but we estimated that it could produce about 1/7 of the unresolved CXB. We placed an upper limit on the space density of postulated X-ray-emitting early black holes at z greater than 7.5 and compared it with supermassive black hole evolution models.

  3. THE DEVELOPMENT AND BACKGROUND OF THE POSITION ANALYSIS QUESTIONNAIRE

    DTIC Science & Technology

    The report deals with the background and the development of the Position Analysis Questionnaire ( PAQ ), which was used as the basic job analysis...instrument in the research program. The PAQ (Form A) used in the study includes 189 job elements of an essentially ’worker-oriented’ nature, these elements...characterize certain aspects of the context within which human work is performed. The job elements of the PAQ have been used as the basis for deriving various

  4. Long-range correlation in cosmic microwave background radiation.

    PubMed

    Movahed, M Sadegh; Ghasemi, F; Rahvar, Sohrab; Tabar, M Reza Rahimi

    2011-08-01

    We investigate the statistical anisotropy and gaussianity of temperature fluctuations of Cosmic Microwave Background (CMB) radiation data from the Wilkinson Microwave Anisotropy Probe survey, using the Multifractal Detrended Fluctuation Analysis, Rescaled Range, and Scaled Windowed Variance methods. Multifractal Detrended Fluctuation Analysis shows that CMB fluctuations has a long-range correlation function with a multifractal behavior. By comparing the shuffled and surrogate series of CMB data, we conclude that the multifractality nature of the temperature fluctuation of CMB radiation is mainly due to the long-range correlations, and the map is consistent with a gaussian distribution.

  5. Top soil radioactivity assessment in a high natural radiation background area: the case of Vinaninkarena, Antsirabe-Madagascar.

    PubMed

    Rabesiranana, Naivo; Rasolonirina, Martin; Terina, Franck; Solonjara, Asivelo F; Andriambololona, Raoelina

    2008-11-01

    The village of Vinaninkarena, Antsirabe, Madagascar (47 degrees 02'40''E, 19 degrees 57'17''S) is located in a high natural radioactivity area. In order to evaluate the natural radionuclide content in soil, sampling was done on-site by the transect method (85 soil samples) and off-site through transects across and beyond the region (up to a range of 100 km), to determine the natural radioactivity variation within vs. outside the region, and to detect significant differences, taking into account spatial variability.

  6. The Majorana Low-noise Low-background Front-end Electronics

    NASA Astrophysics Data System (ADS)

    Abgrall, N.; Aguayo, E.; Avignone, F. T.; Barabash, A. S.; Bertrand, F. E.; Boswell, M.; Brudanin, V.; Busch, M.; Byram, D.; Caldwell, A. S.; Chan, Y.-D.; Christofferson, C. D.; Combs, D. C.; Cuesta, C.; Detwiler, J. A.; Doe, P. J.; Efremenko, Yu.; Egorov, V.; Ejiri, H.; Elliott, S. R.; Fast, J. E.; Finnerty, P.; Fraenkle, F. M.; Galindo-Uribarri, A.; Giovanetti, G. K.; Goett, J.; Green, M. P.; Gruszko, J.; Guiseppe, V. E.; Gusev, K.; Hallin, A. L.; Hazama, R.; Hegai, A.; Henning, R.; Hoppe, E. W.; Howard, S.; Howe, M. A.; Keeter, K. J.; Kidd, M. F.; Kochetov, O.; Konovalov, S. I.; Kouzes, R. T.; LaFerriere, B. D.; Leon, J.; Leviner, L. E.; Loach, J. C.; MacMullin, J.; MacMullin, S.; Martin, R. D.; Meijer, S.; Mertens, S.; Nomachi, M.; Orrell, J. L.; O'Shaughnessy, C.; Overman, N. R.; Phillips, D. G.; Poon, A. W. P.; Pushkin, K.; Radford, D. C.; Rager, J.; Rielage, K.; Robertson, R. G. H.; Romero-Romero, E.; Ronquest, M. C.; Schubert, A. G.; Shanks, B.; Shima, T.; Shirchenko, M.; Snavely, K. J.; Snyder, N.; Suriano, A. M.; Thompson, J.; Timkin, V.; Tornow, W.; Trimble, J. E.; Varner, R. L.; Vasilyev, S.; Vetter, K.; Vorren, K.; White, B. R.; Wilkerson, J. F.; Wiseman, C.; Xu, W.; Yakushev, E.; Young, A. R.; Yu, C.-H.; Yumatov, V.

    The MAJORANA DEMONSTRATOR will search for the neutrinoless double beta decay (ββ(0ν)) of the isotope 76Ge with a mixed array of enriched and natural germanium detectors. In view of the next generation of tonne-scale germanium-based ββ(0ν)-decay searches, a major goal of the MAJORANA DEMONSTRATOR is to demonstrate a path forward to achieving a background rate at or below 1 cnt/(ROI-t-y) in the 4 keV region of interest (ROI) around the 2039-keV Q-value of the 76Ge ββ(0ν)-decay. Such a requirement on the background level significantly constrains the design of the readout electronics, which is further driven by noise and energy resolution performances. We present here the low-noise low- background front-end electronics developed for the low-capacitance p-type point contact (P-PC) germanium detectors of the MAJORANA DEMONSTRATOR. This resistive-feedback front-end, specifically designed to have low mass, is fabricated on a radioassayed fused-silica substrate where the feedback resistor consists of a sputtered thin film of high purity amorphous germanium and the feedback capacitor is based on the capacitance between gold conductive traces.

  7. Background monitoring and its role in global estimation and forecast of the state of the biosphere.

    PubMed

    Izrael, Y A

    1982-12-01

    (1) Scientific grounds and the concept of monitoring as the system for observations, assessment and prediction of man-induced changes in the state of natural environment, the program and aims of the background monitoring were developed by the author in 1972-1980. These questions were discussed in detail at the International Symposium on Global Integrated Monitoring (Riga, U.S.S.R., December, 1978). It should be stressed that along with significant anthropogenic loading on large cities and industrial areas, natural ecosystems covering most of the Earth's territory are also exposed to quite extended, though insignificant anthropogenic effects. This paper proposes to consider the ways of the background information use for the biosphere state assessment and prediction. (2) Classification of objects for monitoring from the point of view of the consequences of the man-made impact, pollution in the first hand, is as follows: - population (public health); - ecosystem elements employed by man whose production is used by population (soil, water bodies, forest, etc.); - biotic elements of ecosystems (without the immediate consumed production); - abiotic constituents of natural ecosystems, considerable components of the biosphere, climatic system. (3) Historically, monitoring in all countries involves the first two spheres. The background monitoring also extends on the next two spheres. It should differentially take into account physical, chemical and biological factors of impacts. Indentification of biological effects is most complex and vital. Human impact at the background level proceeds indirectly through a general (global or regional) deterioration of the state of the biosphere. (4) Gradually the background monitoring is being practiced on a larger and larger scale. It is shown that the long-range atmospheric transport of pollutants in various regions leads to a gradual general increase of all the natural media pollution and to perceptible biological effects (soil and

  8. Francis Bacon's natural history and the Senecan natural histories of early modern Europe.

    PubMed

    Jalobeanu, Dana

    2012-01-01

    At various stages in his career, Francis Bacon claimed to have reformed and changed traditional natural history in such a way that his new "natural and experimental history" was unlike any of its ancient or humanist predecessors. Surprisingly, such claims have gone largely unquestioned in Baconian scholarship. Contextual readings of Bacon's natural history have compared it, so far, only with Plinian or humanist natural history. This paper investigates a different form of natural history, very popular among Bacon's contemporaries, but yet unexplored by contemporary students of Bacon's works. I have provisionally called this form of natural history'Senecan' natural history, partly because it took shape in the Neo-Stoic revival of the sixteenth-century, partly because it originates in a particular cosmographical reading of Seneca's Naturales quaestiones. I discuss in this paper two examples of Senecan natural history: the encyclopedic and cosmographical projects of Pierre de la Primaudaye (1546-1619) and Samuel Purchas (1577-1626). I highlight a number of similarities between these two projects and Francis Bacon's natural history, and argue that Senecan natural history forms an important aspect in the historical and philosophical background that needs to be taken into consideration if we want to understand the extent to which Bacon's project to reform natural history can be said to be new.

  9. DSMC simulation of the interaction between rarefied free jets

    NASA Technical Reports Server (NTRS)

    Dagum, Leonardo; Zhu, S. H. K.

    1993-01-01

    This paper presents a direct simulation Monte Carlo (DSMC) calculation of two interacting free jets exhausting into vacuum. The computed flow field is compared against available experimental data and shows excellent agreement everywhere except in the very near field (less than one orifice diameter downstream of the jet exhaust plane). The lack of agreement in this region is attributed to having assumed an inviscid boundary condition for the orifice lip. The results serve both to validate the DSMC code for a very complex, three dimensional non-equilibrium flow field, and to provide some insight as to the complicated nature of this flow.

  10. Tufted hair folliculitis: a case report and literature review.

    PubMed

    Broshtilova, V; Bardarov, E; Kazandjieva, J; Marina, S

    2011-01-01

    Tufted hair folliculitis is a rare folliculitis of the scalp that resolves with patches of scarring alopecia within multiple hair tufts emerging from dilated follicular orifices. Tufting of hair is caused by clustering of adjacent follicular units due to a fibrosing process and to retention of telogen hairs within a dilated follicular orifice. Various pathogenetic mechanisms have been proposed including nevoid abnormalities, recurrent infections of the follicles, and retention of telogen hair in the tufts. We present a patient with tufted hair folliculitis who was effectively treated with antibacterial medications, verifying the infectious nature of the disease.

  11. The diffuse soft X-ray background as seen with the Einstein Observatory

    NASA Technical Reports Server (NTRS)

    Micela, G.; Sciortino, S.; Vaiana, G. S.; Harnden, F. R., Jr.; Rosner, R.

    1991-01-01

    A systematic survey of the diffuse soft X-ray background as seen directly with the Einstein Observatory is presented. With the aid of 1633 selected 1 x 1 deg fields of view obtained by the IPC to provide about 5-percent sky coverage, with some bias toward the Galactic plane, the background in the 0.16-3.5 keV spectral region was spatially resolved on this angular scale. Maps of the background are characterized and produced at different energies within the Einstein passband. It is confirmed that the Galactic ridge is not present at energies below 0.33 keV and it is demonstrated that the appearance of the ridge above this energy is not due to hard Galactic sources with a flux above 10 exp -13 ergs/sq cm/s. A southern Galactic region is identified, with l between 80 and 180 deg and b less than -5 deg, where the mean background intensity has the lowest value and is homogeneous within better than 9 percent. The implications of these results for the Galactic structure and for the nature of the extragalactic X-ray background are discussed.

  12. More than Meets the Eye--a Simulation of Natural Selection.

    ERIC Educational Resources Information Center

    Allen, J. A.; And Others

    1987-01-01

    Presents experiments using wild birds as predators and pastry as prey and colored stones as background to demonstrate natural selection. Describes the exercise as an exercise in simulating natural selection. (Author/CW)

  13. 40 CFR Table W - 7 of Subpart W-Default Methane Emission Factors for Natural Gas Distribution

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Valve 0.557 Control Valve 9.34 Pressure Relief Valve 0.27 Orifice Meter 0.212 Regulator 0.772 Open-ended Line 26.131 Population Emission Factors—Below Grade Metering-Regulating station 1 Components, Gas... 100 to 300 psig 0.20 Below Grade M&R Station, Inlet Pressure Population Emission...

  14. Background matching by means of dorsal color change in treefrog populations (Hyla japonica).

    PubMed

    Choi, Noori; Jang, Yikweon

    2014-02-01

    Treefrogs change dorsal coloration to match background colors, presumably for predator avoidance. Dorsal coloration in treefrogs results from rearrangement of pigment granules in dermal chromatophores. This physiological basis for color change suggests that brightness and chroma are the color components that may change in response to background color. However, results of experiments are conflicting in that there is no consensus as to which color component is critical for color change in treefrogs. We tested predictions of the physiological model for color change in treefrogs by investigating dorsal color change under five background colors in three different populations of the treefrog Hyla japonica. Differences in color components between background colors and frogs were used as a measure of background matching. Throughout a 1-week experimental period, brightness and chroma differences decreased monotonically, while hue difference remained constant for all background colors. Chroma differences were smaller with the natural colors such as green and brown than with achromatic colors. Moreover, variation in color change among frogs from three localities that differed in land cover suggested that chroma change capacity may be sensitive to environmental conditions. Under the white background color, however, decreasing brightness difference seemed to be crucial to background matching. Furthermore, chroma difference and brightness difference did not decrease indefinitely, suggesting a trade-off between chroma difference and brightness difference under the white background. Thus, background matching may generally occur by decreasing chroma difference under most background colors in H. japonica, but brightness matching may be important under the white color. © 2013 Wiley Periodicals, Inc.

  15. Issues and progress in determining background ozone and particle concentrations

    NASA Astrophysics Data System (ADS)

    Pinto, J. P.

    2011-12-01

    Exposure to ambient ozone is associated with a variety of health outcomes ranging from mild breathing discomfort to mortality. For the purpose of health risk and policy assessments EPA evaluates the anthropogenic increase in ozone above background concentrations and has defined the North American (NA) background concentration of O3 as that which would occur in the U.S. in the absence of anthropogenic emissions of precursors in the U.S., Canada, and Mexico. Monthly average NA background ozone has been used to evaluate health risks, but EPA and state air quality managers must also estimate day specific ozone background levels for high ozone episodes as part of urban scale photochemical modeling efforts to support ozone regulatory programs. The background concentration of O3 is of more concern than other air pollutants because it typically represents a much larger fraction of observed O3 than do the backgrounds of other criteria pollutants (particulate matter (PM), CO, NO2, SO2). NA background cannot be determined directly from ambient monitoring data because of the influence of NA precursor emissions on formation of ozone within NA. Instead, estimates of NA background O3 have been based on GEOS-Chem using simulations in which NA anthropogenic precursor emissions are zeroed out. Thus, modeled NA background O3 includes contributions from natural sources of precursors (including CH4, NMVOCs, NOx, and CO) everywhere in the world, anthropogenic sources of precursors outside of NA, and downward transport of O3 from the stratosphere. Although monitoring data cannot determine NA background directly, measurements by satellites, aircraft, ozonesondes and surface monitors have proved to be highly useful for identifying sources of background O3 and for evaluating the performance of the GEOS-Chem model. Model simulated NA background concentrations are strong functions of location and season with large inter-day variability and with values increasing with elevation and higher in

  16. The soft X-ray diffuse background

    NASA Technical Reports Server (NTRS)

    Mccammon, D.; Burrows, D. N.; Sanders, W. T.; Kraushaar, W. L.

    1982-01-01

    Maps of the diffuse X-ray background intensity covering essentially the entire sky with approx. 7 deg spatial resolution are presented for seven energy bands. The data were obtained on a series of ten sounding rocket flights conducted over a seven-year period. The different nature of the spatial distributions in different bands implies at least three distinct origins for the diffuse X-rays, none of which is well-understood. At energies or approx. 2000 eV, an isotropic and presumably extraglalactic 500 and 1000 eV, an origin which is at least partially galactic seems called for. At energies 284 eV, the observed intensity is anticorrelated with neutral hydrogen column density, but we find it unlikely that this anticorrelation is simply due to absorption of an extragalactic or halo source.

  17. Optimal background matching camouflage.

    PubMed

    Michalis, Constantine; Scott-Samuel, Nicholas E; Gibson, David P; Cuthill, Innes C

    2017-07-12

    Background matching is the most familiar and widespread camouflage strategy: avoiding detection by having a similar colour and pattern to the background. Optimizing background matching is straightforward in a homogeneous environment, or when the habitat has very distinct sub-types and there is divergent selection leading to polymorphism. However, most backgrounds have continuous variation in colour and texture, so what is the best solution? Not all samples of the background are likely to be equally inconspicuous, and laboratory experiments on birds and humans support this view. Theory suggests that the most probable background sample (in the statistical sense), at the size of the prey, would, on average, be the most cryptic. We present an analysis, based on realistic assumptions about low-level vision, that estimates the distribution of background colours and visual textures, and predicts the best camouflage. We present data from a field experiment that tests and supports our predictions, using artificial moth-like targets under bird predation. Additionally, we present analogous data for humans, under tightly controlled viewing conditions, searching for targets on a computer screen. These data show that, in the absence of predator learning, the best single camouflage pattern for heterogeneous backgrounds is the most probable sample. © 2017 The Authors.

  18. Below-Background Ionizing Radiation as an Environmental Cue for Bacteria

    DOE PAGES

    Castillo, Hugo; Smith, Geoffrey B.

    2017-02-14

    All organisms on earth grow under the influence of a natural and relatively constant dose of ionizing radiation referred to as background radiation, and so cells have different mechanisms to prevent the accumulation of damage caused by its different components. However, current knowledge of the deleterious effects of radiation on cells is based on the exposure to acute and high or to chronic, above background doses of radiation and therefore is not appropriate to explain the cellular and biochemical mechanisms that cells employ to sense and respond to chronic below-background levels. Studies at below-background radiation doses can provide insight intomore » the biological role of radiation, as suggested by several examples of what appears to be a stress response in cells grown at doses that range from 10 to 79 times lower than background. Here, we discuss some of the technical constraints to shield cells from radiation to below-background levels, as well as different approaches used to detect and measure responses to such unusual environmental conditions. Then, we present data from Shewanella oneidensis and Deinococcus radiodurans experiments that show how two taxonomically distant bacterial species sense and respond to unnaturally low levels of radiation. Finally, in brief, we grew S. oneidensis and D. radiodurans in liquid culture at dose rates of 72.05 (control) and 0.91 (treatment) nGy hr -1 (including radon) for up to 72 h and measured cell density and the expression of stress-related genes. Our results suggest that a stress response is triggered in the absence of normal levels of radiation.« less

  19. Below-Background Ionizing Radiation as an Environmental Cue for Bacteria

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Castillo, Hugo; Smith, Geoffrey B.

    All organisms on earth grow under the influence of a natural and relatively constant dose of ionizing radiation referred to as background radiation, and so cells have different mechanisms to prevent the accumulation of damage caused by its different components. However, current knowledge of the deleterious effects of radiation on cells is based on the exposure to acute and high or to chronic, above background doses of radiation and therefore is not appropriate to explain the cellular and biochemical mechanisms that cells employ to sense and respond to chronic below-background levels. Studies at below-background radiation doses can provide insight intomore » the biological role of radiation, as suggested by several examples of what appears to be a stress response in cells grown at doses that range from 10 to 79 times lower than background. Here, we discuss some of the technical constraints to shield cells from radiation to below-background levels, as well as different approaches used to detect and measure responses to such unusual environmental conditions. Then, we present data from Shewanella oneidensis and Deinococcus radiodurans experiments that show how two taxonomically distant bacterial species sense and respond to unnaturally low levels of radiation. Finally, in brief, we grew S. oneidensis and D. radiodurans in liquid culture at dose rates of 72.05 (control) and 0.91 (treatment) nGy hr -1 (including radon) for up to 72 h and measured cell density and the expression of stress-related genes. Our results suggest that a stress response is triggered in the absence of normal levels of radiation.« less

  20. Repeal of Comprehensive Background Check Policies and Firearm Homicide and Suicide.

    PubMed

    Kagawa, Rose M C; Castillo-Carniglia, Alvaro; Vernick, Jon S; Webster, Daniel; Crifasi, Cassandra; Rudolph, Kara E; Cerdá, Magdalena; Shev, Aaron; Wintemute, Garen J

    2018-04-02

    In 2016, firearms killed 38,658 people in the United States. Federal law requires licensed gun dealers, but not private parties, to conduct background checks on prospective firearm purchasers with the goal of preventing prohibited persons from obtaining firearms. Our objective was to estimate the effect of the repeal of comprehensive background check laws - requiring a background check for all handgun sales, not just sales by licensed dealers - on firearm homicide and suicide rates in Indiana and Tennessee. We compared age-adjusted firearm homicide and suicide rates, measured annually from 1981-2008 and 1994-2008 in Indiana and Tennessee, respectively, to rates in control groups constructed using the synthetic control method. The average rates of firearm homicide and suicide in Indiana and Tennessee following repeal were within the range of what could be expected given natural variation (differences = 0.7 firearm homicides and 0.5 firearm suicides per 100,000 residents in Indiana and 0.4 firearm homicides and 0.3 firearm suicides per 100,000 residents in Tennessee). Sensitivity analyses resulted in similar findings. We found no evidence of an association between the repeal of comprehensive background check policies and firearm homicide and suicide rates in Indiana and Tennessee. In order to understand whether comprehensive background check policies reduce firearm deaths in the United States generally, more evidence on the impact of such policies from other states is needed.

  1. Concerning evaluation of eco-geochemical background in remediation strategy

    NASA Astrophysics Data System (ADS)

    Korobova, Elena; Romanov, Sergey

    2015-04-01

    The geochemical concept of biosphere developed by V.I. Vernadsky states the geological role of the living organisms in the course of their active chemical interaction with the inert matter (Vernadsky, 1926, 1960). Basing on this theory it is reasonable to suggest that coevolution of living organisms and their environment led to development of the dynamically stable biogeocenoses precisely adequate to their geochemical environment. Soil cover was treated by V.I. Vernadsky as a balanced bio-inert matter resulting from this interaction. Appearance of human mind and then a civilization led to global expansion of human beings, first able to survive in unfavorable geochemical conditions and then starting chemical transformation of the environment to satisfy the growing demands of mankind in food and energy. The residence in unfavorable environment and local contamination was followed by appearance of endemic diseases of plants, animals and man. Therefore zonal, regional and local chemical composition of the soil cover formed in natural conditions may be used for estimation of the optimum geochemical background, most adequate for the corresponding zonal biogeocenoses and species. Moreover, the natural geochemical background and technogenic fields have unequal spatial structure and this facilitates their identification that may be relatively easy realized in remediation strategy. On the assumption of the foregoing, the adequate methodical approach to remediation of technogenically affected areas should account of the interaction of the existing natural and the newly formed technogenic geochemical fields and include the following steps: 1) the study and mapping of geochemical structure of the natural geochemical background basing on soil maps; 2) the study of contaminants and mapping spatial distribution of technogenic releases; 3) construction of risk maps for the target risk groups with due regard to natural ecological threshold concentration in context of risk degree for

  2. How natural hazards influence Internet searches

    NASA Astrophysics Data System (ADS)

    Geyer, Adelina; Martí, Joan; Villaseñor, Antonio

    2017-04-01

    Effective dissemination of correct and easy-to-understand scientific information is one of the most imperative tasks of natural hazard assessment and risk management, being the media and the population the two fundamental groups of receptors. It has been observed how during the occurrence of hazardous natural phenomena, media and population desperately seek for information in all possible channels. Traditionally, these have been the radio and television, but over the past decades, the Internet has also become a significant information resource. Nevertheless, how the Internet search behavior changes during the occurrence of natural phenomena of significant societal impact (i.e. involving important human and/or economic losses) has never been analyzed so far. Focusing mainly on volcanism, we use here for the first time Internet search data provided by Google Trends to examine the search patterns of volcanology-related terms and how these may change during unrest periods or volcanic crises. Results obtained allow us to evaluate, at a global and local scale, the interest of society towards volcanological phenomena and its potential background knowledge of Earth Sciences. We show here how Internet search data turns to be a promising tool for the global and local monitoring of awareness and education background of society on natural phenomena in general, and volcanic hazards in particular.

  3. The inception of pulsed discharges in air: simulations in background fields above and below breakdown

    NASA Astrophysics Data System (ADS)

    Sun, Anbang; Teunissen, Jannis; Ebert, Ute

    2014-11-01

    We investigate discharge inception in air, in uniform background electric fields above and below the breakdown threshold. We perform 3D particle simulations that include a natural level of background ionization in the form of positive and \\text{O}2- ions. In background fields below breakdown, we use a strongly ionized seed of electrons and positive ions to enhance the field locally. In the region of enhanced field, we observe the growth of positive streamers, as in previous simulations with 2D plasma fluid models. The inclusion of background ionization has little effect in this case. When the background field is above the breakdown threshold, the situation is very different. Electrons can then detach from \\text{O}2- and start ionization avalanches in the whole volume. These avalanches together create one extended discharge, in contrast to the ‘double-headed’ streamers found in many fluid simulations.

  4. Modeling background radiation using geochemical data: A case study in and around Cameron, Arizona

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Marsac, Kara E.; Burnley, Pamela C.; Adcock, Christopher T.

    Here, this study compares high-resolution forward models of natural gamma-ray background with that measured by high resolution aerial gamma-ray surveys. The ability to predict variations in natural background radiation levels should prove useful for those engaged in measuring anthropogenic contributions to background radiation for the purpose of emergency response and homeland security operations. The forward models are based on geologic maps and remote sensing multi-spectral imagery combined with two different sources of data: 1) bedrock geochemical data (uranium, potassium and thorium concentrations) collected from national databases, the scientific literature and private companies, and 2) the low spatial resolution NURE (Nationalmore » Uranium Resource Evaluation) aerial gamma-ray survey. The study area near Cameron, Arizona, is located in an arid region with minimal vegetation and, due to the presence of abandoned uranium mines, was the subject of a previous high resolution gamma-ray survey. We found that, in general, geologic map units form a good basis for predicting the geographic distribution of the gamma-ray background. Predictions of background gamma-radiation levels based on bedrock geochemical analyses were not as successful as those based on the NURE aerial survey data sorted by geologic unit. The less successful result of the bedrock geochemical model is most likely due to a number of factors including the need to take into account the evolution of soil geochemistry during chemical weathering and the influence of aeolian addition. Refinements to the forward models were made using ASTER visualizations to create subunits of similar exposure rate within the Chinle Formation, which contains multiple lithologies and by grouping alluvial units by drainage basin rather than age.« less

  5. Modeling background radiation using geochemical data: A case study in and around Cameron, Arizona

    DOE PAGES

    Marsac, Kara E.; Burnley, Pamela C.; Adcock, Christopher T.; ...

    2016-09-16

    Here, this study compares high-resolution forward models of natural gamma-ray background with that measured by high resolution aerial gamma-ray surveys. The ability to predict variations in natural background radiation levels should prove useful for those engaged in measuring anthropogenic contributions to background radiation for the purpose of emergency response and homeland security operations. The forward models are based on geologic maps and remote sensing multi-spectral imagery combined with two different sources of data: 1) bedrock geochemical data (uranium, potassium and thorium concentrations) collected from national databases, the scientific literature and private companies, and 2) the low spatial resolution NURE (Nationalmore » Uranium Resource Evaluation) aerial gamma-ray survey. The study area near Cameron, Arizona, is located in an arid region with minimal vegetation and, due to the presence of abandoned uranium mines, was the subject of a previous high resolution gamma-ray survey. We found that, in general, geologic map units form a good basis for predicting the geographic distribution of the gamma-ray background. Predictions of background gamma-radiation levels based on bedrock geochemical analyses were not as successful as those based on the NURE aerial survey data sorted by geologic unit. The less successful result of the bedrock geochemical model is most likely due to a number of factors including the need to take into account the evolution of soil geochemistry during chemical weathering and the influence of aeolian addition. Refinements to the forward models were made using ASTER visualizations to create subunits of similar exposure rate within the Chinle Formation, which contains multiple lithologies and by grouping alluvial units by drainage basin rather than age.« less

  6. Energy profile of maltooligosaccharide permeation through maltoporin as derived from the structure and from a statistical analysis of saccharide-protein interactions.

    PubMed Central

    Meyer, J. E.; Schulz, G. E.

    1997-01-01

    The crystal structure of the maltodextrin-specific porin from Salmonella typhimurium ligated with a maltotrioside at the pore eyelet is known at 2.4 A resolution. The three glucose units assume a conformation close to the natural amylose helix. The pore eyelet fits exactly the cross-section of a maltooligosaccharide chain and thus functions as a constraining orifice. The oligomer permeates the membrane by screwing along the amylose helix through this orifice. Because each glucose glides along the given helix, its interactions can be sampled at any point along the pathway. The interactions are mostly hydrogen bonds, but also contacts to aromatic rings at one side of the pore. We have derived the energy profile of a gliding maltooligosaccharide by following formation and breakage of hydrogen bonds and by assessing the saccharide-aromatics interactions from a statistical analysis of saccharide binding sites in proteins. The resulting profile indicates smooth permeation despite extensive hydrogen bonding at the orifice. PMID:9144780

  7. Background sources at PEP

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lynch, H.; Schwitters, R.F.; Toner, W.T.

    Important sources of background for PEP experiments are studied. Background particles originate from high-energy electrons and positrons which have been lost from stable orbits, ..gamma..-rays emitted by the primary beams through bremsstrahlung in the residual gas, and synchrotron radiation x-rays. The effect of these processes on the beam lifetime are calculated and estimates of background rates at the interaction region are given. Recommendations for the PEP design, aimed at minimizing background are presented. 7 figs., 4 tabs.

  8. Technologically Enhanced Naturally Occurring Radioactive Materials (TENORM) in the Oil and Gas Industry: A Review.

    PubMed

    Doyi, Israel; Essumang, David Kofi; Dampare, Samuel; Glover, Eric Tetteh

    Radiation is part of the natural environment: it is estimated that approximately 80 % of all human exposure comes from naturally occurring or background radiation. Certain extractive industries such as mining and oil logging have the potential to increase the risk of radiation exposure to the environment and humans by concentrating the quantities of naturally occurring radiation beyond normal background levels (Azeri-Chirag-Gunashli 2004).

  9. The Majorana low-noise low-background front-end electronics

    DOE PAGES

    Abgrall, N.; Aguayo, E.; Avignone, III, F. T.; ...

    2015-03-24

    The Majorana Demonstrator will search for the neutrinoless double beta decay (ββ(0ν)) of the isotope ⁷⁶Ge with a mixed array of enriched and natural germanium detectors. In view of the next generation of tonne-scale germanium-based ββ(0ν)-decay searches, a major goal of the Majorana Demonstrator is to demonstrate a path forward to achieving a background rate at or below 1 cnt/(ROI-t-y) in the 4 keV region of interest (ROI) around the 2039-keV Q-value of the ⁷⁶Ge ββ(0ν)-decay. Such a requirement on the background level significantly constrains the design of the readout electronics, which is further driven by noise and energy resolutionmore » performances. We present here the low-noise low-background front-end electronics developed for the low-capacitance p-type point contact (P-PC) germanium detectors of the Majorana Demonstrator. This resistive-feedback front-end, specifically designed to have low mass, is fabricated on a radioassayed fused-silica substrate where the feedback resistor consists of a sputtered thin film of high purity amorphous germanium and the feedback capacitor is based on the capacitance between gold conductive traces.« less

  10. Effect of distributor on performance of a continuous fluidized bed dryer

    NASA Astrophysics Data System (ADS)

    Yogendrasasidhar, D.; Srinivas, G.; Pydi Setty, Y.

    2018-03-01

    Proper gas distribution is very important in fluidized bed drying in industrial practice. Improper distribution of gas may lead to non-idealities like channeling, short circuiting and accumulation which gives rise to non-uniform quality of dried product. Gas distribution depends on the distributor plate used. Gas distribution mainly depends on orifice diameter, number of orifices and opening area of the distributor plate. Small orifice diameter leads to clogging, and a large orifice diameter gives uneven distribution of gas. The present work involves experimental studies using different distributor plates and simulation studies using ASPEN PLUS steady state simulator. The effect of various parameters such as orifice diameter, number of orifices and the opening area of the distributor plate on the performance of fluidized bed dryer have been studied through simulation and experimentation. Simulations were carried out (i) with increasing air inlet temperature to study the characteristics of solid temperature and moisture in outlet (ii) with increasing orifice diameter and (iii) with increase in number orifices to study the solid outlet temperature profiles. It can be observed from the simulation that, an increase in orifice diameter and number orifices increases solid outlet temperature upto certain condition and then after there is no effect with further increase. Experiments were carried out with increasing opening area (3.4 to 42%) in the form of increasing orifice diameter keeping the number of orifices constant and increasing number of orifices of the distributor plate keeping the orifice diameter constant. It can be seen that the drying rate and solid outlet temperature increase upto certain condition and then after with further increase in the orifice diameter and number of orifices, the change in the drying rate and solid outlet temperature observed is little. The optimum values of orifice diameter and number of orifices from experimentation are found to be 5

  11. The Joint Effects of Background Selection and Genetic Recombination on Local Gene Genealogies

    PubMed Central

    Zeng, Kai; Charlesworth, Brian

    2011-01-01

    Background selection, the effects of the continual removal of deleterious mutations by natural selection on variability at linked sites, is potentially a major determinant of DNA sequence variability. However, the joint effects of background selection and genetic recombination on the shape of the neutral gene genealogy have proved hard to study analytically. The only existing formula concerns the mean coalescent time for a pair of alleles, making it difficult to assess the importance of background selection from genome-wide data on sequence polymorphism. Here we develop a structured coalescent model of background selection with recombination and implement it in a computer program that efficiently generates neutral gene genealogies for an arbitrary sample size. We check the validity of the structured coalescent model against forward-in-time simulations and show that it accurately captures the effects of background selection. The model produces more accurate predictions of the mean coalescent time than the existing formula and supports the conclusion that the effect of background selection is greater in the interior of a deleterious region than at its boundaries. The level of linkage disequilibrium between sites is elevated by background selection, to an extent that is well summarized by a change in effective population size. The structured coalescent model is readily extendable to more realistic situations and should prove useful for analyzing genome-wide polymorphism data. PMID:21705759

  12. The joint effects of background selection and genetic recombination on local gene genealogies.

    PubMed

    Zeng, Kai; Charlesworth, Brian

    2011-09-01

    Background selection, the effects of the continual removal of deleterious mutations by natural selection on variability at linked sites, is potentially a major determinant of DNA sequence variability. However, the joint effects of background selection and genetic recombination on the shape of the neutral gene genealogy have proved hard to study analytically. The only existing formula concerns the mean coalescent time for a pair of alleles, making it difficult to assess the importance of background selection from genome-wide data on sequence polymorphism. Here we develop a structured coalescent model of background selection with recombination and implement it in a computer program that efficiently generates neutral gene genealogies for an arbitrary sample size. We check the validity of the structured coalescent model against forward-in-time simulations and show that it accurately captures the effects of background selection. The model produces more accurate predictions of the mean coalescent time than the existing formula and supports the conclusion that the effect of background selection is greater in the interior of a deleterious region than at its boundaries. The level of linkage disequilibrium between sites is elevated by background selection, to an extent that is well summarized by a change in effective population size. The structured coalescent model is readily extendable to more realistic situations and should prove useful for analyzing genome-wide polymorphism data.

  13. Development of CANDLES low background HPGe detector and half-life measurement of 180Tam

    NASA Astrophysics Data System (ADS)

    Chan, W. M.; Kishimoto, T.; Umehara, S.; Matsuoka, K.; Suzuki, K.; Yoshida, S.; Nakajima, K.; Iida, T.; Fushimi, K.; Nomachi, M.; Ogawa, I.; Tamagawa, Y.; Hazama, R.; Takemoto, Y.; Nakatani, N.; Takihira, Y.; Tozawa, M.; Kakubata, H.; Trang, V. T. T.; Ohata, T.; Tetsuno, K.; Maeda, T.; Khai, B. T.; Li, X. L.; Batpurev, T.

    2018-01-01

    A low background HPGe detector system was developed at CANDLES Experimental Hall for multipurpose use. Various low background techniques were employed, including hermatic shield design, radon gas suppression, and background reduction analysis. A new pulse shape discrimination (PSD) method was specially created for coaxial Ge detector. Using this PSD method, microphonics noise and background event at low energy region less than 200 keV can be rejected effectively. Monte Carlo simulation by GEANT4 was performed to acquire the detection efficiency and study the interaction of gamma-rays with detector system. For rare decay measurement, the detector was utilized to detect the nature's most stable isomer tantalum-180m (180Tam) decay. Two phases of tantalum physics run were completed with total livetime of 358.2 days, which Phase II has upgraded shield configuration. The world most stringent half-life limit of 180Tam has been successfully achieved.

  14. Biomedical aspects of natural and manufactured environmental radioactivity

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hodge, V.

    1996-12-31

    While weapons testing has altered natural radioactivity background, manufactured radioactivity in most parts of the world constitutes but a very small fraction of the total alpha, beta, and gamma radioactivity in soil, air, water, and the biota. For example, in the early 1970s, we found what appeared to be the highest natural concentration of radioactivity ever reported in fish while attempting to measure the manufactured plutonium ({sup 239}Pu and {sup 240}Pu) in organs of oceanic tuna. The natural alpha emitter polonium ({sup 210}Po) was discovered in the same organs at orders of magnitude higher concentrations. In particular, the caecum, whichmore » is a digestive organ composed of many small closed-ended sacs, contained concentrations of polonium as high as 79 pCi/g of wet tissue and lesser amounts of two manufactured isotopes: 0.0001 pCi/g of plutonium and 0.01 pCi/g of radiocesium ({sup 137}Cs). This equates to {approximately}80 rem/yr of radiation dose to this organ, overwhelmingly from the natural polonium, or {approximately}5000 times higher than is found in the human liver, the highest polonium concentration in man. The average background radiation for humans, for comparison, is {approximately}0.2 rem/yr, but the dose for Japanese, whose diet is high in seafood, is {approximately}15 rem/yr. The question arose: {open_quotes}Are these high concentrations of natural polonium limited to oceanic fish?{close_quotes} To answer this question, polonium was determined in the organs of striped bass and catfish from Lake Mead. In a related study, the plutonium and radiocesium ({sup 137}Cs) distributions in soils were determined to ascertain the impact of weapons testing on the natural background radioactivity of soils.« less

  15. NATURALIZATION OF U.S. IMMIGRANTS

    PubMed Central

    Woodrow-Lafield, Karen A.; Xu, Xiaohe; Kersen, Thomas; Poch, Bunnak

    2008-01-01

    The saga of U.S. immigrant naturalization is merely sketched for about 25 million immigrants entered in three decades of renewed immigration. This study documents naturalization outcomes for immigrants from ten major countries of origin, using administrative records on immigrants and naturalizations. Following the 1978-1987 admission cohorts for the first decade or more of permanent residence, this study finds significant covariate effects on the timing of naturalization by origin, mode of entry, and immigrant visa class, net other influences of demographic and background characteristics. Immigrants from the Philippines, Vietnam, and China, naturalized more quickly than immigrants from India, Korea, Cuba, Colombia, Jamaica, the Dominican Republic, and Mexico. Those who adjusted from statuses as nonimmigrants, refugees, or asylees became naturalized citizens more quickly. Those immigrants with employment-sponsorship naturalized faster than family-sponsored immigrants. Spouses of citizens, spouses of permanent residents, spouses of siblings of citizens, and spouses of sons and daughters of citizens naturalized faster than some other immigrants. Gender was not significant in the multivariate analysis but further research will more fully explore sex-specific variation in the timing of naturalization given likely variation in women’s representation by origin and admission categories. PMID:19122767

  16. Beta/gamma and alpha backgrounds in CRESST-II Phase 2

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Strauss, R.; Angloher, G.; Ferreiro Iachellini, N.

    2015-06-01

    The experiment CRESST-II aims at the detection of dark matter with scintillating CaWO{sub 4} crystals operated as cryogenic detectors. Recent results on spin-independent WIMP-nucleon scattering from the CRESST-II Phase 2 allowed to probe a new region of parameter space for WIMP masses below 3 GeV/c{sup 2}. This sensitivity was achieved after background levels were reduced significantly. We present extensive background studies of a CaWO{sub 4} crystal, called TUM40, grown at the Technische Universität München. The average beta/gamma rate of 3.51/[kg keV day] (1-40 keV) and the total intrinsic alpha activity from natural decay chains of 3.08±0.04 mBq/kg are the lowestmore » reported for CaWO{sub 4} detectors. Contributions from cosmogenic activation, surface-alpha decays, external radiation and intrinsic alpha/beta emitters are investigated in detail. A Monte-Carlo based background decomposition allows to identify the origin of the majority of beta/gamma events in the energy region relevant for dark matter search.« less

  17. Rain-induced increase in background radiation detected by Radiation Portal Monitors.

    PubMed

    Livesay, R J; Blessinger, C S; Guzzardo, T F; Hausladen, P A

    2014-11-01

    A complete understanding of both the steady state and transient background measured by Radiation Portal Monitors (RPMs) is essential to predictable system performance, as well as maximization of detection sensitivity. To facilitate this understanding, a test bed for the study of natural background in RPMs has been established at the Oak Ridge National Laboratory. This work was performed in support of the Second Line of Defense Program's mission to enhance partner country capability to deter, detect, and interdict the illicit movement of special nuclear material. In the present work, transient increases in gamma-ray counting rates in RPMs due to rain are investigated. The increase in background activity associated with rain, which has been well documented in the field of environmental radioactivity, originates primarily from the wet-deposition of two radioactive daughters of (222)Rn, namely, (214)Pb and (214)Bi. In this study, rainfall rates recorded by a co-located weather station are compared with RPM count rates and high-purity germanium spectra. The data verify that these radionuclides are responsible for the largest environmental background fluctuations in RPMs. Analytical expressions for the detector response function in Poly-Vinyl Toluene have been derived. Effects on system performance and potential mitigation strategies are discussed. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. Pixel detectors in double beta decay experiments, a new approach for background reduction

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Jose, J. M.; Čermák, P.; Štekl, I.

    Double beta decay (ββ) experiments are challenging frontiers in contemporary physics. These experiments have the potential to investigate more about neutrinos (eg. nature and mass). The main challenge for these experiments is the reduction of background. The group at IEAP, CTU in Prague is investigating a new approach using pixel detectors Timepix. Pixel detector offer background reduction capabilities with its ability to identify the particle interaction (from the 2D signature it generates). However, use of pixel detectors has some challenges such as the presence of readout electronics near the sensing medium and heat dissipation. Different aspects of pixel setup (identificationmore » of radio-impurities, selection of radio-pure materials) and proposed experimental setup are presented. Also, results of preliminary background measurements (performed on the surface and in the underground laboratories) using the prototype setups are presented.« less

  19. Why do trees die? Characterizing the drivers of background tree mortality

    USGS Publications Warehouse

    Das, Adrian J.; Stephenson, Nathan L.; Davis, Kristin P.

    2016-01-01

    The drivers of background tree mortality rates—the typical low rates of tree mortality found in forests in the absence of acute stresses like drought—are central to our understanding of forest dynamics, the effects of ongoing environmental changes on forests, and the causes and consequences of geographical gradients in the nature and strength of biotic interactions. To shed light on factors contributing to background tree mortality, we analyzed detailed pathological data from 200,668 tree-years of observation and 3,729 individual tree deaths, recorded over a 13-yr period in a network of old-growth forest plots in California's Sierra Nevada mountain range. We found that: (1) Biotic mortality factors (mostly insects and pathogens) dominated (58%), particularly in larger trees (86%). Bark beetles were the most prevalent (40%), even though there were no outbreaks during the study period; in contrast, the contribution of defoliators was negligible. (2) Relative occurrences of broad classes of mortality factors (biotic, 58%; suppression, 51%; and mechanical, 25%) are similar among tree taxa, but may vary with tree size and growth rate. (3) We found little evidence of distinct groups of mortality factors that predictably occur together on trees. Our results have at least three sets of implications. First, rather than being driven by abiotic factors such as lightning or windstorms, the “ambient” or “random” background mortality that many forest models presume to be independent of tree growth rate is instead dominated by biotic agents of tree mortality, with potentially critical implications for forecasting future mortality. Mechanistic models of background mortality, even for healthy, rapidly growing trees, must therefore include the insects and pathogens that kill trees. Second, the biotic agents of tree mortality, instead of occurring in a few predictable combinations, may generally act opportunistically and with a relatively large degree of independence from

  20. Does human activity impact the natural antibiotic resistance background? Abundance of antibiotic resistance genes in 21 Swiss lakes.

    PubMed

    Czekalski, Nadine; Sigdel, Radhika; Birtel, Julia; Matthews, Blake; Bürgmann, Helmut

    2015-08-01

    Antibiotic resistance genes (ARGs) are emerging environmental contaminants, known to be continuously discharged into the aquatic environment via human and animal waste. Freshwater aquatic environments represent potential reservoirs for ARG and potentially allow sewage-derived ARG to persist and spread in the environment. This may create increased opportunities for an eventual contact with, and gene transfer to, human and animal pathogens via the food chain or drinking water. However, assessment of this risk requires a better understanding of the level and variability of the natural resistance background and the extent of the human impact. We have analyzed water samples from 21 Swiss lakes, taken at sampling points that were not under the direct influence of local contamination sources and analyzed the relative abundance of ARG using quantitative real-time PCR. Copy numbers of genes mediating resistance to three different broad-spectrum antibiotic classes (sulfonamides: sul1, sul2, tetracyclines: tet(B), tet(M), tet(W) and fluoroquinolones: qnrA) were normalized to copy numbers of bacterial 16S rRNA genes. We used multiple linear regression to assess if ARG abundance is related to human activities in the catchment, microbial community composition and the eutrophication status of the lakes. Sul genes were detected in all sampled lakes, whereas only four lakes contained quantifiable numbers of tet genes, and qnrA remained below detection in all lakes. Our data indicate higher abundance of sul1 in lakes with increasing number and capacity of wastewater treatment plants (WWTPs) in the catchment. sul2 abundance was rather related to long water residence times and eutrophication status. Our study demonstrates the potential of freshwater lakes to preserve antibiotic resistance genes, and provides a reference for ARG abundance from lake systems with low human impact as a baseline for assessing ARG contamination in lake water. Copyright © 2015 Elsevier Ltd. All rights

  1. Modeling background radiation using geochemical data: A case study in and around Cameron, Arizona.

    PubMed

    Marsac, Kara E; Burnley, Pamela C; Adcock, Christopher T; Haber, Daniel A; Malchow, Russell L; Hausrath, Elisabeth M

    2016-12-01

    This study compares high resolution forward models of natural gamma-ray background with that measured by high resolution aerial gamma-ray surveys. The ability to predict variations in natural background radiation levels should prove useful for those engaged in measuring anthropogenic contributions to background radiation for the purpose of emergency response and homeland security operations. The forward models are based on geologic maps and remote sensing multi-spectral imagery combined with two different sources of data: 1) bedrock geochemical data (uranium, potassium and thorium concentrations) collected from national databases, the scientific literature and private companies, and 2) the low spatial resolution NURE (National Uranium Resource Evaluation) aerial gamma-ray survey. The study area near Cameron, Arizona, is located in an arid region with minimal vegetation and, due to the presence of abandoned uranium mines, was the subject of a previous high resolution gamma-ray survey. We found that, in general, geologic map units form a good basis for predicting the geographic distribution of the gamma-ray background. Predictions of background gamma-radiation levels based on bedrock geochemical analyses were not as successful as those based on the NURE aerial survey data sorted by geologic unit. The less successful result of the bedrock geochemical model is most likely due to a number of factors including the need to take into account the evolution of soil geochemistry during chemical weathering and the influence of aeolian addition. Refinements to the forward models were made using ASTER visualizations to create subunits of similar exposure rate within the Chinle Formation, which contains multiple lithologies and by grouping alluvial units by drainage basin rather than age. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  2. Astronomy: social background of students of the integrated high school

    NASA Astrophysics Data System (ADS)

    Voelzke, M. R.; Barbosa, J. I. L.

    2017-07-01

    Astronomy-related contents exist in almost all levels of basic education in Brazil and are also frequently disseminated through mass media. Thus, students form their own explanations about the phenomena studied by this science. Therefore, this work has the objective of identifying the possible social background of the Integrated High School students on the term Astronomy. It is a research of a basic nature, descriptive, and for that reason a quali-quantitative approach was adopted; the procedures to obtain the data were effected in the form of a survey. The results show that the tested students have a social background about the object Astronomy, which is on the one hand fortified by elements they have made or which is part of the experience lived by the respondents within the formal space of education, and on the other hand based on elements possibly disseminated through the mass media.

  3. Backgrounds in Language.

    ERIC Educational Resources Information Center

    Maxwell, John C.; Long, Barbara K.

    "Backgrounds in Language," a field-tested inservice course designed for use by groups of 15 or 25 language arts teachers, provides the subject matter background teachers need to make informed decisions about what curriculum materials to use in what way, at what time, and with which students. The course is comprised of eight 2-hour sessions,…

  4. Hollow cathodes for arcjet thrusters

    NASA Technical Reports Server (NTRS)

    Luebben, Craig R.; Wilbur, Paul J.

    1987-01-01

    In an attempt to prevent exterior spot emission, hollow cathode bodies and orifice plates were constructed from boron nitride which is an electrical insulator, but the orifice plates melted and/or eroded at high interelectrode pressures. The most suitable hollow cathodes tested included a refractory metal orifice plate in a boron nitride body, with the insert insulated electrically from the orifice plate. In addition, the hollow cathode interior was evacuated to assure a low pressure at the insert surface, thus promoting diffuse electron emission. At high interelectrode pressures, the electrons tended to flow through the orifice plate rather than through the orifice, which could result in overheating of the orifice plate. Using a carefully aligned centerline anode, electron flow through the orifice could be sustained at interelectrode pressures up to 500 torr - but the current flow path still occasionally jumped from the orifice to the orifice plate. Based on these tests, it appears that a hollow cathode would operate most effectively at pressures in the arcjet regime with a refractory, chemically stable, and electrically insulating cathode body and orifice plate.

  5. Vocational Education and Training for People from Non-English-Speaking Backgrounds. Review of Research.

    ERIC Educational Resources Information Center

    Volkoff, Veronica; Golding, Barry

    Research on the provision of vocational education and training (VET) for Australia's very culturally diverse work force with non-English-speaking backgrounds (NESBs) considers the extent and nature of the disadvantage. The current definition of NESB limits membership to those born overseas; a proposed two-pronged approach is based on "first…

  6. Background noise exerts diverse effects on the cortical encoding of foreground sounds.

    PubMed

    Malone, B J; Heiser, Marc A; Beitel, Ralph E; Schreiner, Christoph E

    2017-08-01

    In natural listening conditions, many sounds must be detected and identified in the context of competing sound sources, which function as background noise. Traditionally, noise is thought to degrade the cortical representation of sounds by suppressing responses and increasing response variability. However, recent studies of neural network models and brain slices have shown that background synaptic noise can improve the detection of signals. Because acoustic noise affects the synaptic background activity of cortical networks, it may improve the cortical responses to signals. We used spike train decoding techniques to determine the functional effects of a continuous white noise background on the responses of clusters of neurons in auditory cortex to foreground signals, specifically frequency-modulated sweeps (FMs) of different velocities, directions, and amplitudes. Whereas the addition of noise progressively suppressed the FM responses of some cortical sites in the core fields with decreasing signal-to-noise ratios (SNRs), the stimulus representation remained robust or was even significantly enhanced at specific SNRs in many others. Even though the background noise level was typically not explicitly encoded in cortical responses, significant information about noise context could be decoded from cortical responses on the basis of how the neural representation of the foreground sweeps was affected. These findings demonstrate significant diversity in signal in noise processing even within the core auditory fields that could support noise-robust hearing across a wide range of listening conditions. NEW & NOTEWORTHY The ability to detect and discriminate sounds in background noise is critical for our ability to communicate. The neural basis of robust perceptual performance in noise is not well understood. We identified neuronal populations in core auditory cortex of squirrel monkeys that differ in how they process foreground signals in background noise and that may

  7. Monitoring Energy Calibration Drift Using the Scintillator Background Radiation

    NASA Astrophysics Data System (ADS)

    Conti, Maurizio; Eriksson, Lars; Hayden, Charles

    2011-06-01

    Scintillating materials commonly used in nuclear medicine can contain traces of isotopes that naturally emit gamma or beta radiation. Examples of these are 138La contained in LaBr3 and other Lanthanum based scintillators, and 176Lu contained in LSO, LYSO, LuYAP and other Lutetium based scintillators. In particular,176Lu decays into 176Hf and emits a beta particle with maximum energy 589 keV, and a cascade of gamma rays of energies 307 keV, 202 keV and 88 keV. We propose to use the background radiation for monitoring of detector calibration drift and for self-calibration of detectors in complex detector systems. A calibration drift due to random or systematic changes in photomultiplier tube (PMT) gain was studied in a Siemens PET scanner, based on LSO blocks. Both a conventional radioactive source (68Ge, 511 keV photons from electron-positron annihilation) and the LSO background radiation were used for calibration. The difference in the calibration peak shift at 511 keV estimated with the two methods was less than 10%.

  8. Naturally Occurring Fish Poisons from Plants

    ERIC Educational Resources Information Center

    Cannon, Jonathan G.; Burton, Robert A.; Wood, Steven G.; Owen, Noel L.

    2004-01-01

    The fish poisons derived from plants used throughout the world, not only as piscicides but also for a range of other uses, including insecticident and in folk medicines, is presented. The aim of this review is to provide a useful background for students interested in natural products.

  9. Tensor modes in pure natural inflation

    NASA Astrophysics Data System (ADS)

    Nomura, Yasunori; Yamazaki, Masahito

    2018-05-01

    We study tensor modes in pure natural inflation [1], a recently-proposed inflationary model in which an axionic inflaton couples to pure Yang-Mills gauge fields. We find that the tensor-to-scalar ratio r is naturally bounded from below. This bound originates from the finiteness of the number of metastable branches of vacua in pure Yang-Mills theories. Details of the model can be probed by future cosmic microwave background experiments and improved lattice gauge theory calculations of the θ-angle dependence of the vacuum energy.

  10. Visual signal detection in structured backgrounds. II. Effects of contrast gain control, background variations, and white noise

    NASA Technical Reports Server (NTRS)

    Eckstein, M. P.; Ahumada, A. J. Jr; Watson, A. B.

    1997-01-01

    Studies of visual detection of a signal superimposed on one of two identical backgrounds show performance degradation when the background has high contrast and is similar in spatial frequency and/or orientation to the signal. To account for this finding, models include a contrast gain control mechanism that pools activity across spatial frequency, orientation and space to inhibit (divisively) the response of the receptor sensitive to the signal. In tasks in which the observer has to detect a known signal added to one of M different backgrounds grounds due to added visual noise, the main sources of degradation are the stochastic noise in the image and the suboptimal visual processing. We investigate how these two sources of degradation (contrast gain control and variations in the background) interact in a task in which the signal is embedded in one of M locations in a complex spatially varying background (structured background). We use backgrounds extracted from patient digital medical images. To isolate effects of the fixed deterministic background (the contrast gain control) from the effects of the background variations, we conduct detection experiments with three different background conditions: (1) uniform background, (2) a repeated sample of structured background, and (3) different samples of structured background. Results show that human visual detection degrades from the uniform background condition to the repeated background condition and degrades even further in the different backgrounds condition. These results suggest that both the contrast gain control mechanism and the background random variations degrade human performance in detection of a signal in a complex, spatially varying background. A filter model and added white noise are used to generate estimates of sampling efficiencies, an equivalent internal noise, an equivalent contrast-gain-control-induced noise, and an equivalent noise due to the variations in the structured background.

  11. 40 CFR Table W - 7 of Subpart W of Part 98-Default Methane Emission Factors for Natural Gas Distribution

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Connector 1.69 Block Valve 0.557 Control Valve 9.34 Pressure Relief Valve 0.27 Orifice Meter 0.212 Regulator 0.772 Open-ended Line 26.131 Population Emission Factors—Below Grade Metering-Regulating station 1..., Inlet Pressure 100 to 300 psig 0.20 Below Grade M&R Station, Inlet Pressure Population...

  12. 40 CFR Table W - 7 of Subpart W of Part 98-Default Methane Emission Factors for Natural Gas Distribution

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Connector 1.69 Block Valve 0.557 Control Valve 9.34 Pressure Relief Valve 0.27 Orifice Meter 0.212 Regulator 0.772 Open-ended Line 26.131 Population Emission Factors—Below Grade Metering-Regulating station 1..., Inlet Pressure 100 to 300 psig 0.20 Below Grade M&R Station, Inlet Pressure Population...

  13. Effects of Convective Transport on the Budget of Amazonian Aerosol under Background Conditions

    NASA Astrophysics Data System (ADS)

    Wang, J.; Krejci, R.; Giangrande, S. E.; Kuang, C.; Barbosa, H. M.; Brito, J.; Carbone, S.; Chi, X.; Comstock, J. M.; Ditas, F.; Lavric, J. V.; Manninen, H. E.; Mei, F.; Moran, D.; Pöhlker, C.; Pöhlker, M. L.; Saturno, J.; Schmid, B.; Souza, R. A. F. D.; Springston, S. R.; Tomlinson, J. M.; Toto, T.; Walter, D.; Wimmer, D.; Smith, J. N.; Machado, L.; Artaxo, P.; Andreae, M. O.; Martin, S. T.

    2016-12-01

    Aerosol particles can strongly influence the radiative properties of clouds, and they represent one of the largest uncertainties in computer simulations of climate change. The large uncertainty is in large part due to a poor understanding of processes under natural conditions, which serves as the baseline to measure change against. Understanding the processes under natural conditions is critical for a reliable assessment and quantification of ongoing and future climate change. The Amazon rainforest is one of the few continental regions where aerosol particles and their precursors can be studied under near-natural conditions. Here we examine the aerosol number and CCN budget under background conditions in the Amazon basin using data collected during the Observations and Modeling of the Green Ocean Amazon (GoAmazon 2014/5) campaign, which took place from January 2014 to December 2015 near Manaus, Brazil. The aerosol size spectrum was observed at the Amazon Tall Tower Observatory (ATTO), 150 km upwind of Manaus, and its variation with convection and precipitation during the wet season is presented. Air masses arriving at the ATTO during the wet season are typically brought by the northeasterly trade winds and travel across at least 1000 km of undeveloped tropical rainforest, therefore are generally clean. Also shown are vertical profiles of aerosol observed onboard the DOE Gulfstream-1 research aircraft. The impact of convective transport on the budget of boundary layer aerosol and CCN under the background conditions is discussed.

  14. Comparing Background and Recent Erosion Rates in Degraded Areas of Southeastern Brazil

    NASA Astrophysics Data System (ADS)

    Fernandes, N.; Bierman, P. R.; Sosa-Gonzalez, V.; Rood, D. H.; Fontes, R. L.; Santos, A. C.; Godoy, J. M.; Bhering, S.

    2014-12-01

    Soil erosion is a major problem in northwestern Rio de Janeiro State where, during the last three centuries, major land-use changes took place, associated with the replacement of the original rainforest by agriculture and grazing. The combination of steep hillslopes, erodible soils, sparse vegetation, natural and human-induced fires, as well as downslope ploughing, led to an increase in surface runoff and surface erosion on soil-mantled hillslopes; together, these actions and responses caused a decline in soil productivity. In order to estimate changes in erosion rates over time, we compared erosion rates measured at different spatial and temporal scales, both background (natural) and short-term (human-induced during last few decades). Background long-term erosion rates were measured using in-situ produced cosmogenic 10Be in the sand fraction quartz of active river channel sediment in four basins in the northwestern portion of Rio de Janeiro State. In these basins, average annual precipitation varies from 1,200 to 1,300 mm, while drainage areas vary from 15 to 7,200 km2. Short-term erosion rates were measured in one of these basins from fallout 210Pb in soil samples collected along a hillslope transect located in an abandoned agriculture field. In this transect, 190 undisturbed soil samples (three replicates) were collected from the surface to 0.50 m depth (5 cm vertical intervals) in six soil pits. 10Be average background, basin-wide, erosion rates in the area are ~ 13 m/My; over the last decades, time-integrated (210Pb) average hillslope erosion rates are around 1450 m/Myr, with maximum values at the steepest portion of convex hillslopes of about 2000 m/Myr. These results suggest that recent hillslope erosion rates are about 2 orders of magnitude above background rates of sediment generation integrated over many millennia. This unsustainable rate of soil loss has severely decreased soil productivity eventually leading to the abandonment of farming activities in

  15. Natural and man-made hexavalent chromium, Cr(VI), in groundwater near a mapped plume, Hinkley, California—study progress as of May 2017, and a summative-scale approach to estimate background Cr(VI) concentrations

    USGS Publications Warehouse

    Izbicki, John A.; Groover, Krishangi D.

    2018-03-22

    This report describes (1) work done between January 2015 and May 2017 as part of the U.S. Geological Survey (USGS) hexavalent chromium, Cr(VI), background study and (2) the summative-scale approach to be used to estimate the extent of anthropogenic (man-made) Cr(VI) and background Cr(VI) concentrations near the Pacific Gas and Electric Company (PG&E) natural gas compressor station in Hinkley, California. Most of the field work for the study was completed by May 2017. The summative-scale approach and calculation of Cr(VI) background were not well-defined at the time the USGS proposal for the background Cr(VI) study was prepared but have since been refined as a result of data collected as part of this study. The proposed summative scale consists of multiple items, formulated as questions to be answered at each sampled well. Questions that compose the summative scale were developed to address geologic, hydrologic, and geochemical constraints on Cr(VI) within the study area. Each question requires a binary (yes or no) answer. A score of 1 will be assigned for an answer that represents data consistent with anthropogenic Cr(VI); a score of –1 will be assigned for an answer that represents data inconsistent with anthropogenic Cr(VI). The areal extent of anthropogenic Cr(VI) estimated from the summative-scale analyses will be compared with the areal extent of anthropogenic Cr(VI) estimated on the basis of numerical groundwater flow model results, along with particle-tracking analyses. On the basis of these combined results, background Cr(VI) values will be estimated for “Mojave-type” deposits, and other deposits, in different parts of the study area outside the summative-scale mapped extent of anthropogenic Cr(VI).

  16. Bonding with the Natural World: The Roots of Environmental Awareness

    ERIC Educational Resources Information Center

    Chawla, Louise

    2013-01-01

    With delicate literary style and allusions, Louise Chawla combines her ecological research and Montessori background to portray the unfolding of childhood in natural places. Starting with "enchantment with the world" as the basis for nature education for the child under six, the article suggests that the "loose parts" in the…

  17. Why do trees die? Characterizing the drivers of background tree mortality.

    PubMed

    Das, Adrian J; Stephenson, Nathan L; Davis, Kristin P

    2016-10-01

    The drivers of background tree mortality rates-the typical low rates of tree mortality found in forests in the absence of acute stresses like drought-are central to our understanding of forest dynamics, the effects of ongoing environmental changes on forests, and the causes and consequences of geographical gradients in the nature and strength of biotic interactions. To shed light on factors contributing to background tree mortality, we analyzed detailed pathological data from 200,668 tree-years of observation and 3,729 individual tree deaths, recorded over a 13-yr period in a network of old-growth forest plots in California's Sierra Nevada mountain range. We found that: (1) Biotic mortality factors (mostly insects and pathogens) dominated (58%), particularly in larger trees (86%). Bark beetles were the most prevalent (40%), even though there were no outbreaks during the study period; in contrast, the contribution of defoliators was negligible. (2) Relative occurrences of broad classes of mortality factors (biotic, 58%; suppression, 51%; and mechanical, 25%) are similar among tree taxa, but may vary with tree size and growth rate. (3) We found little evidence of distinct groups of mortality factors that predictably occur together on trees. Our results have at least three sets of implications. First, rather than being driven by abiotic factors such as lightning or windstorms, the "ambient" or "random" background mortality that many forest models presume to be independent of tree growth rate is instead dominated by biotic agents of tree mortality, with potentially critical implications for forecasting future mortality. Mechanistic models of background mortality, even for healthy, rapidly growing trees, must therefore include the insects and pathogens that kill trees. Second, the biotic agents of tree mortality, instead of occurring in a few predictable combinations, may generally act opportunistically and with a relatively large degree of independence from one another

  18. Background Underground at WIPP

    NASA Astrophysics Data System (ADS)

    Esch, Ernst-Ingo; Hime, A.; Bowles, T. J.

    2001-04-01

    Recent interest to establish a dedicated underground laboratory in the United States prompted an experimental program at to quantify the enviromental backgrounds underground at the Waste Isolation Pilot Plant (WIPP) in Carlsbad, New Mexico. An outline of this program is provided along with recent experimental data on the cosmic ray muon flux at the 650 meter level of WIPP. The implications of the cosmic ray muon and fast neutron background at WIPP will be discussed in the context of new generation, low background experiments envisioned in the future.

  19. Multiphoton amplitude in a constant background field

    NASA Astrophysics Data System (ADS)

    Ahmad, Aftab; Ahmadiniaz, Naser; Corradini, Olindo; Kim, Sang Pyo; Schubert, Christian

    2018-01-01

    In this contribution, we present our recent compact master formulas for the multiphoton amplitudes of a scalar propagator in a constant background field using the worldline fomulation of quantum field theory. The constant field has been included nonperturbatively, which is crucial for strong external fields. A possible application is the scattering of photons by electrons in a strong magnetic field, a process that has been a subject of great interest since the discovery of astrophysical objects like radio pulsars, which provide evidence that magnetic fields of the order of 1012G are present in nature. The presence of a strong external field leads to a strong deviation from the classical scattering amplitudes. We explicitly work out the Compton scattering amplitude in a magnetic field, which is a process of potential relevance for astrophysics. Our final result is compact and suitable for numerical integration.

  20. Number Sense in the Transition from Natural to Rational Numbers

    ERIC Educational Resources Information Center

    Van Hoof, Jo; Verschaffel, Lieven; Van Dooren, Wim

    2017-01-01

    Background: Rational numbers are of critical importance both in mathematics and in other fields of science. However, they form a stumbling block for learners. One widely known source of the difficulty learners have with rational numbers is the natural number bias, that is the tendency to (inappropriately) apply natural number properties in…

  1. The orifice revisited: women in gynaecological texts.

    PubMed

    Koutroulis, G

    1990-01-01

    A content analysis was carried out on obstetric and gynaecological textbooks recommended for medical students at four Australian universities. The texts were read for a hidden curriculum of sexist ideology. This study is a partial replication of a study carried out by Scully and Bart in the United States eighteen years ago. The findings of Scully and Bart demonstrated that obstetric and gynaecological texts contained outdated and erroneous views about women's sexuality and portrayed women in stereotyped roles. It was anticipated that institutionalized changes may have occurred since the time that Scully and Bart carried out their research and the texts would reflect this accordingly; particularly with the effect of the women's health movement which has been expressing dissatisfaction with the health care system. The findings of this research show that sexist ideology still pervades the obstetric and gynaecological texts, though to a lesser extent than eighteen years ago. There are some differences from what Scully and Bart discovered, but major similarities were found. The main difference between the results of this study and the findings of Scully and Bart, is that the majority of texts analysed here did not contain outdated and incorrect information about women's sexual response. For example, none of the texts refer to vaginal orgasm as the 'mature' response for women. The main similarity is that women's sexuality is still depicted with a heterosexual perspective, with marriage and mothering the 'natural' aspirations of all women.

  2. Mapping gravitational-wave backgrounds using methods from CMB analysis: Application to pulsar timing arrays

    NASA Astrophysics Data System (ADS)

    Gair, Jonathan; Romano, Joseph D.; Taylor, Stephen; Mingarelli, Chiara M. F.

    2014-10-01

    We describe an alternative approach to the analysis of gravitational-wave backgrounds, based on the formalism used to characterize the polarization of the cosmic microwave background. In contrast to standard analyses, this approach makes no assumptions about the nature of the background and so has the potential to reveal much more about the physical processes that generated it. An arbitrary background can be decomposed into modes whose angular dependence on the sky is given by gradients and curls of spherical harmonics. We derive the pulsar timing overlap reduction functions for the individual modes, which are given by simple combinations of spherical harmonics evaluated at the pulsar locations. We show how these can be used to recover the components of an arbitrary background, giving explicit results for both isotropic and anisotropic uncorrelated backgrounds. We also find that the response of a pulsar timing array to curl modes is identically zero, so half of the gravitational-wave sky will never be observed using pulsar timing, no matter how many pulsars are included in the array. An isotropic, unpolarized and uncorrelated background can be accurately represented using only three modes, and so a search of this type will be only slightly more complicated than the standard cross-correlation search using the Hellings and Downs overlap reduction function. However, by measuring the components of individual modes of the background and checking for consistency with isotropy, this approach has the potential to reveal much more information. Each individual mode on its own describes a background that is correlated between different points on the sky. A measurement of the components that indicates the presence of correlations in the background on large angular scales would suggest startling new physics.

  3. On the detection of a stochastic background of gravitational radiation by the Doppler tracking of spacecraft

    NASA Technical Reports Server (NTRS)

    Mashhoon, B.; Grishchuk, L. P.

    1980-01-01

    Consideration is given to the possibility of detection of an isotropic background gravitational radiation of a stochastic nature by the method of Doppler tracking of spacecraft. Attention is given in the geometrical optics limit, to the general formula for the frequency shift of an electromagnetic signal in the gravitational radiation field, and it is shown to be gauge independent. The propagation of a free electromagnetic wave in a gravitational radiation field is examined with the conclusion that no resonance phenomena can be expected. Finally, the 'Doppler noise' due to a stochastic background is evaluated, and it is shown to depend on the total energy density of the background and a parameter that is a characteristic of the radiation spectrum and the detection system used.

  4. Dilatonic parallelizable NS-NS backgrounds

    NASA Astrophysics Data System (ADS)

    Kawano, Teruhiko; Yamaguchi, Satoshi

    2003-08-01

    We complete the classification of parallelizable NS-NS backgrounds in type II supergravity by adding the dilatonic case to the result of Figueroa-O'Farrill on the non-dilatonic case. We also study the supersymmetry of these parallelizable backgrounds. It is shown that all the dilatonic parallelizable backgrounds have sixteen supersymmetries.

  5. Aliasing of the Schumann resonance background signal by sprite-associated Q-bursts

    NASA Astrophysics Data System (ADS)

    Guha, Anirban; Williams, Earle; Boldi, Robert; Sátori, Gabriella; Nagy, Tamás; Bór, József; Montanyà, Joan; Ortega, Pascal

    2017-12-01

    The Earth's naturally occurring Schumann resonances (SR) are composed of a quasi-continuous background component and a larger-amplitude, short-duration transient component, otherwise called 'Q-burst' (Ogawa et al., 1967). Sprites in the mesosphere are also known to accompany the energetic positive ground flashes that launch the Q-bursts (Boccippio et al., 1995). Spectra of the background Schumann Resonances (SR) require a natural stabilization period of ∼10-12 min for the three conspicuous modal parameters to be derived from Lorentzian fitting. Before the spectra are computed and the fitting process is initiated, the raw time series data need to be properly filtered for local cultural noise, narrow band interference as well as for large transients in the form of global Q-bursts. Mushtak and Williams (2009) describe an effective technique called Isolated Lorentzian (I-LOR), in which, the contributions from local cultural and various other noises are minimized to a great extent. An automated technique based on median filtering of time series data has been developed. These special lightning flashes are known to have greater contribution in the ELF range (below 1 kHz) compared to general negative CG strikes (Huang et al., 1999; Cummer et al., 2006). The global distributions of these Q-bursts have been studied by Huang et al. (1999) Rhode Island, USA by wave impedance methods from single station ELF measurements at Rhode Island, USA and from Japan Hobara et al. (2006). The present work aims to demonstrate the effect of Q-bursts on SR background spectra using GPS time-stamped observation of TLEs. It is observed that the Q-bursts selected for the present work do alias the background spectra over a 5-s period, though the amplitudes of these Q-bursts are far below the background threshold of 16 Core Standard Deviation (CSD) so that they do not strongly alias the background spectra of 10-12 min duration. The examination of one exceptional Q-burst shows that appreciable

  6. Optically modulated fluorescence bioimaging: visualizing obscured fluorophores in high background.

    PubMed

    Hsiang, Jung-Cheng; Jablonski, Amy E; Dickson, Robert M

    2014-05-20

    improved slightly, SAFIRe yields up to 100-fold improved signal visibility by essentially removing obscuring, unmodulated background (Richards, C. I.; J. Am. Chem. Soc. 2009, 131, 4619). While SAFIRe exhibits a wide, linear dynamic range, we have demonstrated single-molecule signal recovery buried within 200 nM obscuring dye. In addition to enabling signal recovery through background reduction, each dye exhibits a characteristic modulation frequency indicative of its photophysical dynamics. Thus, these characteristic time scales offer opportunities not only to expand the dimensionality of fluorescence imaging by using dark-state lifetimes but also to distinguish the dynamics of subpopulations on the basis of photophysical versus diffusional time scales, even within modulatable populations. The continued development of modulation for signal recovery and observation of biological dynamics holds great promise for studying a range of transient biological phenomena in natural environments. Through the development of a wide range of fluorescent proteins, organic dyes, and inorganic emitters that exhibit significant dark-state populations under steady-state illumination, we can drastically expand the applicability of fluorescence imaging to probe lower-abundance complexes and their dynamics.

  7. Concentration of gold in natural waters

    USGS Publications Warehouse

    McHugh, J.B.

    1988-01-01

    The purpose of this paper is to investigate the amount of gold present in natural waters. One hundred and thirty-two natural water samples were collected from various sources and analyzed for gold by the latest techniques. Background values for gold in natural waters range from <0.001 to 0.005 ppb, and anomalous values range from 0.010 to 2.8 ppb. Waters collected from mineralized areas have a mean gold value of 0.101 ppb, whereas waters collected from unmineralized areas have a mean of 0.002 ppb. Some of the high gold values reported in the earlier literature were probably due to interferences by high salt content in the sample and/or lack of proper filter procedures. ?? 1988.

  8. Soil dioxins levels at agriculture sites and natural preserve areas of Taiwan.

    PubMed

    Jou, Jin-juh; Lin, Kae-Long; Chung, Jen-Chir; Liaw, Shu-Liang

    2007-08-17

    In this study, agriculture soil in Taiwan has been sampled and analyzed to determine the background level of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/DF) in the agricultural and nature preserve areas. Another objective is to investigate relationship between soil characteristics and air deposition in Taiwan. The results indicate that in nature preserve areas the topsoil shows an extraordinary profile of PCDD/DF compared to that in the air deposition. The PCDD/DF levels of the low-contaminated agricultural soils are compatible with those of the nature preserves soils. However, in the highly-contaminated agricultural soils, there is an abrupt jump in their concentrations, 10-100 times higher. The overall I-TEQ values of the background topsoils range from 0.101 to 15.2 ng I-TEQ/kg. Near industrial/urban areas in Taiwan the PCDD/DF are slightly higher compared to those in the low concentration group. Typically, the PCDD/DF background values found in this survey fall in the 90% confidence interval and can thus, be deemed the background levels in Taiwan. Ninety-five percent of these data are below the European and American soil standard of 10 ng I-TEQ/kg d.w. The PCDD/DF profile with one neighborhood soil sample was shown no significant difference.

  9. Improving Academic Outcomes in Poor Urban Schools through Nature-Based Learning

    ERIC Educational Resources Information Center

    Camasso, Michael J.; Jagannathan, Radha

    2018-01-01

    This paper presents results from the evaluation of the Nurture thru Nature (NtN) programme, a natural science and environmental education intervention designed to help elementary school children from disadvantaged backgrounds increase their knowledge of science and strengthen overall academic performance. Using an experimental design the pilot NtN…

  10. Systemic Inflammatory Response After Natural Orifice Translumenal Surgery: Transvaginal Cholecystectomy in a Porcine Model

    PubMed Central

    Fan, Joe K. M.; Tong, Daniel K. H.; HO, David W. Y.; Luk, John; Law, Simon

    2009-01-01

    Objective: We analyzed circulating TNF-α and IL-6 to determine systemic inflammatory responses associated with transvaginal cholecystectomy in a porcine model. Methods: Six female pigs were used for a survival study after transvaginal cholecystectomy (NOTES group) using endoscopic submucosal dissection (ESD) instruments and a single-channel endoscope. Blood was drawn preoperatively and 24 hours and 48 hours postoperatively. Four pigs were used as controls. In addition, laparoscopic cholecystectomy was performed in 2 pigs for laparoscopic control. Results: In all 6 pigs in the NOTES group, no major intraoperative complications occurred. No significant differences were found between control, laparoscopic, and NOTES groups in terms of preoperative IL-6 level (P=0.897) and at 24 hours (P=0.790), and 48 hours postoperatively (P=0.945). Similarly, there was no significant difference in mean preoperative (P=0.349) and mean day 2 postoperative TNF-α levels (P=0.11). But a significant increase in day 1 postoperative TNF-α levels in the laparoscopic group compared with that in the control and NOTES groups was observed (P=0.049). One limitation of our study is that the sample size was relatively small. Conclusion: NOTES is safe in animal models in terms of anatomical and cellular level changes with minimal systemic inflammatory host responses elicited. Further study needs to be carried out in humans before NOTES can be recommended for routine use. PMID:19366533

  11. Background Radioactivity in River and Reservoir Sediments near Los Alamos, New Mexico

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    S.G.McLin; D.W. Lyons

    2002-05-05

    As part of its continuing Environmental Surveillance Program, regional river and lake-bottom sediments have been collected annually by Los Alamos National Laboratory (the Laboratory) since 1974 and 1979, respectively. These background samples are collected from three drainage basins at ten different river stations and five reservoirs located throughout northern New Mexico and southern Colorado. Radiochemical analyses for these sediments include tritium, strontium-90, cesium-137, total uranium, plutonium-238, plutonium-239,-240, americium-241, gross alpha, gross beta, and gross gamma radioactivity. Detection-limit radioactivity originates as worldwide fallout from aboveground nuclear weapons testing and satellite reentry into Earth's atmosphere. Spatial and temporal variations in individual analytemore » levels originate from atmospheric point-source introductions and natural rate differences in airborne deposition and soil erosion. Background radioactivity values on sediments reflect this variability, and grouped river and reservoir sediment samples show a range of statistical distributions that appear to be analyte dependent. Traditionally, both river and reservoir analyte data were blended together to establish background levels. In this report, however, we group background sediment data according to two criteria. These include sediment source (either river or reservoir sediments) and station location relative to the Laboratory (either upstream or downstream). These grouped data are statistically evaluated through 1997, and background radioactivity values are established for individual analytes in upstream river and reservoir sediments. This information may be used to establish the existence and areal extent of trace-level environmental contamination resulting from historical Laboratory research activities since the early 1940s.« less

  12. Optical Flow for Flight and Wind Tunnel Background Oriented Schlieren Imaging

    NASA Technical Reports Server (NTRS)

    Smith, Nathanial T.; Heineck, James T.; Schairer, Edward T.

    2017-01-01

    Background oriented Schlieren images have historically been generated by calculating the observed pixel displacement between a wind-on and wind-o image pair using normalized cross-correlation. This work uses optical flow to solve the displacement fields which generate the Schlieren images. A well established method used in the computer vision community, optical flow is the apparent motion in an image sequence due to brightness changes. The regularization method of Horn and Schunck is used to create Schlieren images using two data sets: a supersonic jet plume shock interaction from the NASA Ames Unitary Plan Wind Tunnel, and a transonic flight test of a T-38 aircraft using a naturally occurring background, performed in conjunction with NASA Ames and Armstrong Research Centers. Results are presented and contrasted with those using normalized cross-correlation. The optical flow Schlieren images are found to provided significantly more detail. We apply the method to historical data sets to demonstrate the broad applicability and limitations of the technique.

  13. Concepts of Nature and Power: Environmental Ethics of the Northern Ute.

    ERIC Educational Resources Information Center

    Romeo, Stephanie

    1985-01-01

    Describes the approach to resource development of the Northern Ute tribe of Utah. This model preserves the traditional way of life, increases revenues, and minimizes environmental damage. The Ute's historical background and ideology of nature are discussed as well as their fundamental beliefs and moral imperatives associated with natural elements.…

  14. Unsupervised background-constrained tank segmentation of infrared images in complex background based on the Otsu method.

    PubMed

    Zhou, Yulong; Gao, Min; Fang, Dan; Zhang, Baoquan

    2016-01-01

    In an effort to implement fast and effective tank segmentation from infrared images in complex background, the threshold of the maximum between-class variance method (i.e., the Otsu method) is analyzed and the working mechanism of the Otsu method is discussed. Subsequently, a fast and effective method for tank segmentation from infrared images in complex background is proposed based on the Otsu method via constraining the complex background of the image. Considering the complexity of background, the original image is firstly divided into three classes of target region, middle background and lower background via maximizing the sum of their between-class variances. Then, the unsupervised background constraint is implemented based on the within-class variance of target region and hence the original image can be simplified. Finally, the Otsu method is applied to simplified image for threshold selection. Experimental results on a variety of tank infrared images (880 × 480 pixels) in complex background demonstrate that the proposed method enjoys better segmentation performance and even could be comparative with the manual segmentation in segmented results. In addition, its average running time is only 9.22 ms, implying the new method with good performance in real time processing.

  15. The Effect of Background Music in Shark Documentaries on Viewers' Perceptions of Sharks

    PubMed Central

    Hastings, Philip A.; Gneezy, Ayelet

    2016-01-01

    Despite the ongoing need for shark conservation and management, prevailing negative sentiments marginalize these animals and legitimize permissive exploitation. These negative attitudes arise from an instinctive, yet exaggerated fear, which is validated and reinforced by disproportionate and sensationalistic news coverage of shark ‘attacks’ and by highlighting shark-on-human violence in popular movies and documentaries. In this study, we investigate another subtler, yet powerful factor that contributes to this fear: the ominous background music that often accompanies shark footage in documentaries. Using three experiments, we show that participants rated sharks more negatively and less positively after viewing a 60-second video clip of swimming sharks set to ominous background music, compared to participants who watched the same video clip set to uplifting background music, or silence. This finding was not an artifact of soundtrack alone because attitudes toward sharks did not differ among participants assigned to audio-only control treatments. This is the first study to demonstrate empirically that the connotative attributes of background music accompanying shark footage affect viewers’ attitudes toward sharks. Given that nature documentaries are often regarded as objective and authoritative sources of information, it is critical that documentary filmmakers and viewers are aware of how the soundtrack can affect the interpretation of the educational content. PMID:27487003

  16. The Effect of Background Music in Shark Documentaries on Viewers' Perceptions of Sharks.

    PubMed

    Nosal, Andrew P; Keenan, Elizabeth A; Hastings, Philip A; Gneezy, Ayelet

    2016-01-01

    Despite the ongoing need for shark conservation and management, prevailing negative sentiments marginalize these animals and legitimize permissive exploitation. These negative attitudes arise from an instinctive, yet exaggerated fear, which is validated and reinforced by disproportionate and sensationalistic news coverage of shark 'attacks' and by highlighting shark-on-human violence in popular movies and documentaries. In this study, we investigate another subtler, yet powerful factor that contributes to this fear: the ominous background music that often accompanies shark footage in documentaries. Using three experiments, we show that participants rated sharks more negatively and less positively after viewing a 60-second video clip of swimming sharks set to ominous background music, compared to participants who watched the same video clip set to uplifting background music, or silence. This finding was not an artifact of soundtrack alone because attitudes toward sharks did not differ among participants assigned to audio-only control treatments. This is the first study to demonstrate empirically that the connotative attributes of background music accompanying shark footage affect viewers' attitudes toward sharks. Given that nature documentaries are often regarded as objective and authoritative sources of information, it is critical that documentary filmmakers and viewers are aware of how the soundtrack can affect the interpretation of the educational content.

  17. Peripheral prism glasses: effects of moving and stationary backgrounds.

    PubMed

    Shen, Jieming; Peli, Eli; Bowers, Alex R

    2015-04-01

    Unilateral peripheral prisms for homonymous hemianopia (HH) expand the visual field through peripheral binocular visual confusion, a stimulus for binocular rivalry that could lead to reduced predominance and partial suppression of the prism image, thereby limiting device functionality. Using natural-scene images and motion videos, we evaluated whether detection was reduced in binocular compared with monocular viewing. Detection rates of nine participants with HH or quadranopia and normal binocularity wearing peripheral prisms were determined for static checkerboard perimetry targets briefly presented in the prism expansion area and the seeing hemifield. Perimetry was conducted under monocular and binocular viewing with targets presented over videos of real-world driving scenes and still frame images derived from those videos. With unilateral prisms, detection rates in the prism expansion area were significantly lower in binocular than in monocular (prism eye) viewing on the motion background (medians, 13 and 58%, respectively, p = 0.008) but not the still frame background (medians, 63 and 68%, p = 0.123). When the stimulus for binocular rivalry was reduced by fitting prisms bilaterally in one HH and one normally sighted subject with simulated HH, prism-area detection rates on the motion background were not significantly different (p > 0.6) in binocular and monocular viewing. Conflicting binocular motion appears to be a stimulus for reduced predominance of the prism image in binocular viewing when using unilateral peripheral prisms. However, the effect was only found for relatively small targets. Further testing is needed to determine the extent to which this phenomenon might affect the functionality of unilateral peripheral prisms in more real-world situations.

  18. Bilateral choanal atresia in an adult - management with mitomycin C and without stents: a case report

    PubMed Central

    2009-01-01

    Background A 23-year-old female patient presented to the outpatient clinic with bilateral nasal obstruction and discharge since birth. Endoscopic examination and paranasal sinus tomography revealed bilateral choanal atresia. She did not have any other congenital abnormalities. Her parents reported cyanosis in childhood that worsened during feeding and improved during crying; however, they had not visited a physician. She did not have remarkable complaints during early childhood or adolescence. Methods The patient was operated under general anesthesia, using a 0° 4 mm rigid endoscope. The orifice was widened with a curette and, to prevent stenosis, mitomycin-C (1 mg/ml) was applied topically to the nasopharyngeal orifice for 5 minutes. No stents were placed. Results Follow-up evaluation at postoperative 12th month showed that her symptoms improved significantly and, on endoscopic examination, both choanae remained patent. PMID:20062630

  19. Background rejection of TEXONO experiment to explore the sub-keV energy region with HPGe detector

    NASA Astrophysics Data System (ADS)

    Singh, M. K.; Sharma, V.; Singh, L.; Chen, J. H.; Singh, V.; Subrahmanyam, V. S.; Soma, A. K.; Wong, H. T.

    2017-10-01

    To observe the neutrino-nucleus coherent scattering as well as for dark matter search, a detection system with ultra-low energy high purity germanium detector has been set up by the TEXONO Collaboration in Kuo-Sheng Nuclear Power Plant. Owing to the weak nature and small recoil energy of these rare events, understanding of background sources and their contribution to the energy spectrum are the key factors in this experiment. In this report, we will focus in detail on the different sources of backgrounds in the TEXONO experiment and the techniques used to reject/minimize them.

  20. SiPM timing characteristics under conditions of a large background for lidars

    NASA Astrophysics Data System (ADS)

    Antonova, A. M.; Kaplin, V. A.

    2018-01-01

    Silicon photomultipliers (SiPM) have found their use in various fields of industry and scientific experiments. This paper considers study of the SiPM possibility to detect low-intensity light pulses (down to single photons) under high-intensity background illumination. This may be useful for the development of laser rangefinders operating under natural light using SiPM as crucial photosensor. Moreover, the presented data describes some physical properties of LIDAR with SiPM under radiation exposure, which always affects its intrinsic noise.

  1. Alphas and surface backgrounds in liquid argon dark matter detectors

    NASA Astrophysics Data System (ADS)

    Stanford, Christopher J.

    Current observations from astrophysics indicate the presence of dark matter, an invisible form of matter that makes up a large part of the mass of the universe. One of the leading theories for dark matter is that it is made up of Weakly Interacting Massive Particles (WIMPs). One of the ways we try to discover WIMPs is by directly detecting their interaction with regular matter. This can be done using a scintillator such as liquid argon, which gives off light when a particle interacts with it. Liquid argon (LAr) is a favorable means of detecting WIMPs because it has an inherent property that enables a technique called pulse-shape discrimination (PSD). PSD can distinguish a WIMP signal from the constant background of electromagnetic signals from other sources, like gamma rays. However, there are other background signals that PSD is not as capable of rejecting, such as those caused by alpha decays on the interior surfaces of the detector. Radioactive elements that undergo alpha decay are introduced to detector surfaces during construction by radon gas that is naturally present in the air, as well as other means. When these surface isotopes undergo alpha decay, they can produce WIMP-like signals in the detector. We present here two LAr experiments. The first (RaDOSE) discovered a property of an organic compound that led to a technique for rejecting surface alpha decays in LAr detectors with high efficiency. The second (DarkSide-50) is a dark matter experiment operated at LNGS in Italy and is the work of an international collaboration. A detailed look is given into alpha decays and surface backgrounds present in the detector, and projections are made of alpha-related backgrounds for 500 live days of data. The technique developed with RaDOSE is applied to DarkSide-50 to determine its effectiveness in practice. It is projected to suppress the surface background in DarkSide-50 by more than a factor of 1000.

  2. Use of Laboratory-Supplied Natural Gas in Breakthrough Phenomena.

    ERIC Educational Resources Information Center

    Eiceman, G. A.; And Others

    1985-01-01

    Natural gas from regular commercial lines contains enough carbon-8 and above hydrocarbon contaminants to serve as a satisfactory sample for breakthrough experiments. Procedures used, typical results obtained, and theoretical background information are provided. (JN)

  3. Low Background Counting at LBNL

    DOE PAGES

    Smith, A. R.; Thomas, K. J.; Norman, E. B.; ...

    2015-03-24

    The Low Background Facility (LBF) at Lawrence Berkeley National Laboratory in Berkeley, California provides low background gamma spectroscopy services to a wide array of experiments and projects. The analysis of samples takes place within two unique facilities; locally within a carefully-constructed, low background cave and remotely at an underground location that historically has operated underground in Oroville, CA, but has recently been relocated to the Sanford Underground Research Facility (SURF) in Lead, SD. These facilities provide a variety of gamma spectroscopy services to low background experiments primarily in the form of passive material screening for primordial radioisotopes (U, Th, K)more » or common cosmogenic/anthropogenic products, as well as active screening via Neutron Activation Analysis for specific applications. The LBF also provides hosting services for general R&D testing in low background environments on the surface or underground for background testing of detector systems or similar prototyping. A general overview of the facilities, services, and sensitivities is presented. Recent activities and upgrades will also be presented, such as the completion of a 3π anticoincidence shield at the surface station and environmental monitoring of Fukushima fallout. The LBF is open to any users for counting services or collaboration on a wide variety of experiments and projects.« less

  4. C3: The Compositional Construction of Context. A New, More Effective and Efficient Way to Marshal Inferences from Background Knowledge

    DTIC Science & Technology

    2014-09-01

    quarter. Deep natural language understanding , efficient inference, pragmatics, background knowledge U U U SAR 4 Dr. David McDonald (781) 718-1964 C3...effective and efficient way to marshal inferences from background knowledge ’ N00014-13-1-0228 Dr. David McDonald Smart Information Flow Technologies, dba...for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data

  5. Internal erosion rates of a 10-kW xenon ion thruster

    NASA Technical Reports Server (NTRS)

    Rawlin, Vincent K.

    1988-01-01

    A 30 cm diameter divergent magnetic field ion thruster, developed for mercury operation at 2.7 kW, was modified and operated with xenon propellant at a power level of 10 kW for 567 h to evaluate thruster performance and lifetime. The major differences between this thruster and its baseline configuration were elimination of the three mercury vaporizers, use of a main discharge cathode with a larger orifice, reduction in discharge baffle diameter, and use of an ion accelerating system with larger acceleration grid holes. Grid thickness measurement uncertainties, combined with estimates of the effects of reactive residual facility background gases gave a minimum screen grid lifetime of 7000 h. Discharge cathode orifice erosion rates were measured with three different cathodes with different initial orifice diameters. Three potential problems were identified during the wear test: the upstream side of the discharge baffle eroded at an unacceptable rate; two of the main cathode tubes experienced oxidation, deformation, and failure; and the accelerator grid impingement current was more than an order of magnitude higher than that of the baseline mercury thruster. The charge exchange ion erosion was not quantified in this test. There were no measurable changes in the accelerator grid thickness or the accelerator grid hole diameters.

  6. Measurement of low radioactivity background in a high voltage cable by high resolution inductively coupled plasma mass spectrometry

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Vacri, M. L. di; Nisi, S.; Balata, M.

    2013-08-08

    The measurement of naturally occurring low level radioactivity background in a high voltage (HV) cable by high resolution inductively coupled plasma mass spectrometry (HR ICP MS) is presented in this work. The measurements were performed at the Chemistry Service of the Gran Sasso National Laboratory. The contributions to the radioactive background coming from the different components of the heterogeneous material were separated. Based on the mass fraction of the cable, the whole contamination was calculated. The HR ICP MS results were cross-checked by gamma ray spectroscopy analysis that was performed at the low background facility STELLA (Sub Terranean Low Levelmore » Assay) of the LNGS underground lab using HPGe detectors.« less

  7. Pioneer 10 search for gravitational waves - Limits on a possible isotropic cosmic background of radiation in the microhertz region

    NASA Technical Reports Server (NTRS)

    Anderson, J. D.; Mashhoon, B.

    1985-01-01

    The nature of the response of the Doppler tracking system to a stochastic background of gravitational radiation is discussed. Using data acquired in 1981 by the Deep Space Network with the Pioneer 10 spacecraft, interesting upper limits are placed on the energy density of the background in three frequency bands extending from 7 x 10 to the -7th to 10 to the -4th Hz, a region that has been inaccessible previously by any technique.

  8. Responses of auditory-cortex neurons to structural features of natural sounds.

    PubMed

    Nelken, I; Rotman, Y; Bar Yosef, O

    1999-01-14

    Sound-processing strategies that use the highly non-random structure of natural sounds may confer evolutionary advantage to many species. Auditory processing of natural sounds has been studied almost exclusively in the context of species-specific vocalizations, although these form only a small part of the acoustic biotope. To study the relationships between properties of natural soundscapes and neuronal processing mechanisms in the auditory system, we analysed sound from a range of different environments. Here we show that for many non-animal sounds and background mixtures of animal sounds, energy in different frequency bands is coherently modulated. Co-modulation of different frequency bands in background noise facilitates the detection of tones in noise by humans, a phenomenon known as co-modulation masking release (CMR). We show that co-modulation also improves the ability of auditory-cortex neurons to detect tones in noise, and we propose that this property of auditory neurons may underlie behavioural CMR. This correspondence may represent an adaptation of the auditory system for the use of an attribute of natural sounds to facilitate real-world processing tasks.

  9. Genetic background effects in Neuroligin-3 mutant mice: Minimal behavioral abnormalities on C57 background.

    PubMed

    Jaramillo, Thomas C; Escamilla, Christine Ochoa; Liu, Shunan; Peca, Lauren; Birnbaum, Shari G; Powell, Craig M

    2018-02-01

    Neuroligin-3 (NLGN3) is a postsynaptic cell adhesion protein that interacts with presynaptic ligands including neurexin-1 (NRXN1) [Ichtchenko et al., Journal of Biological Chemistry, 271, 2676-2682, 1996]. Mice harboring a mutation in the NLGN3 gene (NL3R451C) mimicking a mutation found in two brothers with autism spectrum disorder (ASD) were previously generated and behaviorally phenotyped for autism-related behaviors. In these NL3R451C mice generated and tested on a hybrid C57BL6J/129S2/SvPasCrl background, we observed enhanced spatial memory and reduced social interaction [Tabuchi et al., Science, 318, 71-76, 2007]. Curiously, an independently generated second line of mice harboring the same mutation on a C57BL6J background exhibited minimal aberrant behavior, thereby providing apparently discrepant results. To investigate the origin of the discrepancy, we previously replicated the original findings of Tabuchi et al. by studying the same NL3R451C mutation on a pure 129S2/SvPasCrl genetic background. Here we complete the behavioral characterization of the NL3R451C mutation on a pure C57BL6J genetic background to determine if background genetics play a role in the discrepant behavioral outcomes involving NL3R451C mice. NL3R451C mutant mice on a pure C57BL6J background did not display spatial memory enhancements or social interaction deficits. We only observed a decreased startle response and mildly increased locomotor activity in these mice suggesting that background genetics influences behavioral outcomes involving the NL3R451C mutation. Autism Res 2018, 11: 234-244. © 2017 International Society for Autism Research, Wiley Periodicals, Inc. Behavioral symptoms of autism can be highly variable, even in cases that involve identical genetic mutations. Previous studies in mice with a mutation of the Neuroligin-3 gene showed enhanced learning and social deficits. We replicated these findings on the same and different genetic backgrounds. In this study, however, the

  10. Three-Dimensional Color Doppler Echocardiography for Direct Measurement of Vena Contracta Area in Mitral Regurgitation

    PubMed Central

    Little, Stephen H.; Pirat, Bahar; Kumar, Rahul; Igo, Stephen R.; McCulloch, Marti; Hartley, Craig J.; Xu, Jiaqiong; Zoghbi, William A.

    2012-01-01

    OBJECTIVES Our goal was to prospectively compare the accuracy of real-time three-dimensional (3D) color Doppler vena contracta (VC) area and two-dimensional (2D) VC diameter in an in vitro model and in the clinical assessment of mitral regurgitation (MR) severity. BACKGROUND Real-time 3D color Doppler allows direct measurement of VC area and may be more accurate for assessment of MR than the conventional VC diameter measurement by 2D color Doppler. METHODS Using a circulatory loop with an incorporated imaging chamber, various pulsatile flow rates of MR were driven through 4 differently sized orifices. In a clinical study of patients with at least mild MR, regurgitation severity was assessed quantitatively using Doppler-derived effective regurgitant orifice area (EROA), and semiquantitatively as recommended by the American Society of Echocardiography. We describe a step-by-step process to accurately identify the 3D-VC area and compare that measure against known orifice areas (in vitro study) and EROA (clinical study). RESULTS In vitro, 3D-VC area demonstrated the strongest correlation with known orifice area (r = 0.92, p < 0.001), whereas 2D-VC diameter had a weak correlation with orifice area (r = 0.56, p = 0.01). In a clinical study of 61 patients, 3D-VC area correlated with Doppler-derived EROA (r = 0.85, p < 0.001); the relation was stronger than for 2D-VC diameter (r = 0.67, p < 0.001). The advantage of 3D-VC area over 2D-VC diameter was more pronounced in eccentric jets (r = 0.87, p < 0.001 vs. r = 0.6, p < 0.001, respectively) and in moderate-to-severe or severe MR (r = 0.80, p < 0.001 vs. r = 0.18, p = 0.4, respectively). CONCLUSIONS Measurement of VC area is feasible with real-time 3D color Doppler and provides a simple parameter that accurately reflects MR severity, particularly in eccentric and clinically significant MR where geometric assumptions may be challenging. PMID:19356505

  11. Background Light Bluer Than Expected

    NASA Image and Video Library

    2014-11-06

    This plot shows data from the Cosmic Infrared Background Experiment, or CIBER, rockets launched in 2010 and 2012. The experiment measures a diffuse glow of infrared light in the sky, known as the cosmic infrared background.

  12. Peripheral Prism Glasses: Effects of Moving and Stationary Backgrounds

    PubMed Central

    Shen, Jieming; Peli, Eli; Bowers, Alex R.

    2015-01-01

    Purpose Unilateral peripheral prisms for homonymous hemianopia (HH) expand the visual field through peripheral binocular visual confusion, a stimulus for binocular rivalry that could lead to reduced predominance (partial local suppression) of the prism image and limit device functionality. Using natural-scene images and motion videos, we evaluated whether detection was reduced in binocular compared to monocular viewing. Methods Detection rates of nine participants with HH or quadranopia and normal binocularity wearing peripheral prisms were determined for static checkerboard perimetry targets briefly presented in the prism expansion area and the seeing hemifield. Perimetry was conducted under monocular and binocular viewing with targets presented over videos of real-world driving scenes and still frame images derived from those videos. Results With unilateral prisms, detection rates in the prism expansion area were significantly lower in binocular than monocular (prism eye) viewing on the motion background (medians 13% and 58%, respectively, p = 0.008), but not the still frame background (63% and 68%, p = 0.123). When the stimulus for binocular rivalry was reduced by fitting prisms bilaterally in 1 HH and 1 normally-sighted subject with simulated HH, prism-area detection rates on the motion background were not significantly different (p > 0.6) in binocular and monocular viewing. Conclusions Conflicting binocular motion appears to be a stimulus for reduced predominance of the prism image in binocular viewing when using unilateral peripheral prisms. However, the effect was only found for relatively small targets. Further testing is needed to determine the extent to which this phenomenon might affect the functionality of unilateral peripheral prisms in more real-world situations. PMID:25785533

  13. Plasma jet ignition device

    DOEpatents

    McIlwain, Michael E.; Grant, Jonathan F.; Golenko, Zsolt; Wittstein, Alan D.

    1985-01-15

    An ignition device of the plasma jet type is disclosed. The device has a cylindrical cavity formed in insulating material with an electrode at one end. The other end of the cylindrical cavity is closed by a metal plate with a small orifice in the center which plate serves as a second electrode. An arc jumping between the first electrode and the orifice plate causes the formation of a highly-ionized plasma in the cavity which is ejected through the orifice into the engine cylinder area to ignite the main fuel mixture. Two improvements are disclosed to enhance the operation of the device and the length of the plasma plume. One improvement is a metal hydride ring which is inserted in the cavity next to the first electrode. During operation, the high temperature in the cavity and the highly excited nature of the plasma breaks down the metal hydride, liberating hydrogen which acts as an additional fuel to help plasma formation. A second improvement consists of a cavity insert containing a plurality of spaced, metal rings. The rings act as secondary spark gap electrodes reducing the voltage needed to maintain the initial arc in the cavity.

  14. Use of Brown Algae to Demonstrate Natural Products Techniques.

    ERIC Educational Resources Information Center

    Porter, Lee A.

    1985-01-01

    Background information is provided on the natural products found in marine organisms in general and the brown algae in particular. Also provided are the procedures needed to isolate D-mannitol (a primary metabolite) and cholesterol from brown algae. (JN)

  15. The background in the $$0\

    DOE PAGES

    Agostini, M.; Allardt, M.; Andreotti, E.; ...

    2014-04-04

    The GERmanium Detector Array (Gerda) experiment at the Gran Sasso underground laboratory (LNGS) of INFN is searching for neutrinoless double beta (0νββ) decay of 76 Ge. The signature of the signal is a monoenergetic peak at 2039 keV, the Q ββ value of the decay. To avoid bias in the signal search, the present analysis does not consider all those events, that fall in a 40 keV wide region centered around Q ββ. The main parameters needed for the 0νββ analysis are described. A background model was developed to describe the observed energy spectrum. The model contains severalmore » contributions, that are expected on the basis of material screening or that are established by the observation of characteristic structures in the energy spectrum. The model predicts a flat energy spectrum for the blinding window around Qββ with a background index ranging from 17.6 to 23.8 × 10 -3 cts/(keV kg yr). A part of the data not considered before has been used to test if the predictions of the background model are consistent. The observed number of events in this energy region is consistent with the background model. The background at Q ββ is dominated by close sources, mainly due to 42 K, 214 Bi, 228 60 Co and α emitting isotopes from the 226 Ra decay chain. The individual fractions depend on the assumed locations of the contaminants. It is shown, that after removal of the known γ peaks, the energy spectrum can be fitted in an energy range of 200 keV around Q ββ with a constant background. This gives a background index consistent with the full model and uncertainties of the same size.« less

  16. A salient region detection model combining background distribution measure for indoor robots.

    PubMed

    Li, Na; Xu, Hui; Wang, Zhenhua; Sun, Lining; Chen, Guodong

    2017-01-01

    Vision system plays an important role in the field of indoor robot. Saliency detection methods, capturing regions that are perceived as important, are used to improve the performance of visual perception system. Most of state-of-the-art methods for saliency detection, performing outstandingly in natural images, cannot work in complicated indoor environment. Therefore, we propose a new method comprised of graph-based RGB-D segmentation, primary saliency measure, background distribution measure, and combination. Besides, region roundness is proposed to describe the compactness of a region to measure background distribution more robustly. To validate the proposed approach, eleven influential methods are compared on the DSD and ECSSD dataset. Moreover, we build a mobile robot platform for application in an actual environment, and design three different kinds of experimental constructions that are different viewpoints, illumination variations and partial occlusions. Experimental results demonstrate that our model outperforms existing methods and is useful for indoor mobile robots.

  17. A Flexible Cosmic Ultraviolet Background Model

    NASA Astrophysics Data System (ADS)

    McQuinn, Matthew

    2016-10-01

    HST studies of the IGM, of the CGM, and of reionization-era galaxies are all aided by ionizing background models, which are a critical input in modeling the ionization state of diffuse, 10^4 K gas. The ionization state in turn enables the determination of densities and sizes of absorbing clouds and, when applied to the Ly-a forest, the global ionizing emissivity of sources. Unfortunately, studies that use these background models have no way of gauging the amount of uncertainty in the adopted model other than to recompute their results using previous background models with outdated observational inputs. As of yet there has been no systematic study of uncertainties in the background model and there unfortunately is no publicly available ultraviolet background code. A public code would enable users to update the calculation with the latest observational constraints, and it would allow users to experiment with varying the background model's assumptions regarding emissions and absorptions. We propose to develop a publicly available ionizing background code and, as an initial application, quantify the level of uncertainty in the ionizing background spectrum across cosmic time. As the background model improves, so does our understanding of (1) the sources that dominate ionizing emissions across cosmic time and (2) the properties of diffuse gas in the circumgalactic medium, the WHIM, and the Ly-a forest. HST is the primary telescope for studying both the highest redshift galaxies and low-redshift diffuse gas. The proposed program would benefit HST studies of the Universe at z 0 all the way up to z = 10, including of high-z galaxies observed in the HST Frontier Fields.

  18. Light and Color in Nature and Art

    NASA Astrophysics Data System (ADS)

    Williamson, Samuel J.; Cummins, Herman Z.

    1983-02-01

    An introduction to the science of light and color and its applications to photography, art, natural phenomena, and other related areas. Explains the origin of phenomena commonly encountered in nature and art, emphasizing the physical aspects but also touching on aspects of physiology and psychology that directly influence how visual images are perceived. Covers the effect of mixing color, the notion of color spaces, how atoms and molecules affect light, how light can be measured, the effect of using a lens, and many other topics. Requires little or no mathematical background. Includes questions and references for further reading.

  19. Effect of altitude on spirometric parameters and the performance of peak flow meters.

    PubMed Central

    Pollard, A. J.; Mason, N. P.; Barry, P. W.; Pollard, R. C.; Collier, D. J.; Fraser, R. S.; Miller, M. R.; Milledge, J. S.

    1996-01-01

    BACKGROUND: Portable peak flow meters are used in clinical practice for measurement of peak expiratory flow (PEF) at many different altitudes throughout the world. Some PEF meters are affected by gas density. This study was undertaken to establish which type of meter is best for use above sea level and to determine changes in spirometric measurements at altitude. METHODS: The variable orifice mini-Wright peak flow meter was compared with the fixed orifice Micro Medical Microplus turbine microspirometer at sea level and at Everest Base Camp (5300 m). Fifty one members of the 1994 British Mount Everest Medical Expedition were studied (age range, 19-55). RESULTS: Mean forced vital capacity (FVC) fell by 5% and PEF rose by 25.5%. However, PEF recorded with the mini-Wright peak flow meter underestimated PEF by 31%, giving readings 6.6% below sea level values. FVC was lowest in the mornings and did not improve significantly with acclimatisation. Lower PEF values were observed on morning readings and were associated with higher acute mountain sickness scores, although the latter may reflect decreased effort in those with acute mountain sickness. There was no change in forced expiratory volume in one second (FEV1) at altitude when measured with the turbine microspirometer. CONCLUSIONS: The cause of the fall in FVC at 5300 m is unknown but may be attributed to changes in lung blood volume, interstitial lung oedema, or early airways closure. Variable orifice peak flow meters grossly underestimate PEF at altitude and fixed orifice devices are therefore preferable where accurate PEF measurements are required above sea level. PMID:8711651

  20. Does the extracorporeal circulation worsen anemia in hemodialysis patients? Investigation with advanced microscopes of red blood cells drawn at the beginning and end of dialysis

    PubMed Central

    Stamopoulos, Dimosthenis; Bakirtzi, Nerantzoula; Manios, Efthymios; Grapsa, Eirini

    2013-01-01

    Background In hemodialysis (HD) patients, anemia relates to three main factors: insufficient production of erythropoietin; impaired management of iron; and decreased lifespan of red blood cells (RBCs). The third factor can relate to structural deterioration of RBCs due to extrinsic (extracorporeal circuit; biochemical activation and/or mechanical stress during dialysis) and intrinsic (uremic milieu; biochemical interference of the RBC membrane constituents with toxins) mechanisms. Herein, we evaluate information accessed with advanced imaging techniques at the cellular level. Methods Atomic force and scanning electron microscopes were employed to survey intact RBCs (iRBCs) of seven HD patients in comparison to seven healthy donors. The extrinsic factor was investigated by contrasting pre- and post-HD samples. The intrinsic environment was investigated by comparing the microscopy data with the clinical ones. Results The iRBC membranes of the enrolled HD patients were overpopulated with orifice-like (high incidence; typical size within 100–1,000 nm) and crevice-like (low incidence; typical size within 500–4,000 nm) defects that exhibited a statistically significant (P < 0.05) relative increase (+55% and +350%, respectively) in respect to healthy donors. The relative variation of the orifice and crevice indices (mean population of orifices and crevices per top membrane surface) between pre- and post-HD was not statistically significant (−3.3% and +4.5%, respectively). The orifice index correlates with the concentrations of urea, calcium, and phosphorus, but not, however, with that of creatinine. Conclusion Extracorporeal circulation is not detrimental to the structural integrity of RBC membranes. Uremic milieu is a candidate cause of RBC membrane deterioration, which possibly worsens anemia. PMID:24143093

  1. Flow visualization in long neck Helmholtz resonators with grazing flow

    NASA Technical Reports Server (NTRS)

    Baumeister, K. J.; Rice, E. J.

    1976-01-01

    Both oscillating and steady flows were applied to a single plexiglass resonator cavity with colored dyes injected in both the orifice and grazing flow field to record the motion of the fluid. For oscillatory flow, the instantaneous dye streamlines were similar for both the short and long-neck orifices. The orifice flow blockage appears to be independent of orifice length for a fixed amplitude of flow oscillation and magnitude of the grazing flow. The steady flow dye studies showed that the acoustic and steady flow resistances do not necessarily correspond for long neck orifices.

  2. Study of the Residual Background Events in Ground Data from the ASTRO-HSXS Microcalorimeter

    NASA Technical Reports Server (NTRS)

    Kilbourne, Caroline A.; Boyce, Kevin R.; Chiao, M. P.; Eckart, M. E.; Kelley, R. L.; Leutenegger, M. A.; Porter, F. S.; Watanabe, T.; Ishisaki, Y.; Yamada, S.; hide

    2015-01-01

    The measured instrumental background of the XRS calorimeter spectrometer of Suzaku had several sources, including primary cosmic rays and secondary particles interacting with the pixels and with the silicon structure of the array. Prior to the launch of Suzaku, several data sets were taken without x-ray illumination to study the characteristics and timing of background signals produced in the array and anti-coincidence detector. Even though the source of the background in the laboratory was different from that in low-earth orbit (muons and environmental gamma-rays on the ground versus Galactic cosmic-ray (GCR) protons and alpha particles in space), the study of correlations and properties of populations of rare events was useful for establishing the preliminary screening parameters needed for selection of good science data. Sea-level muons are singly charged minimum-ionizing particles, like the GCR protons, and thus were good probes of the effectiveness of screening via the signals from the anti-coincidence detector. Here we present the first analysis of the on-ground background of the SXS calorimeter of Astro-H. On XRS, the background prior to screening was completely dominated by coincident events on many pixels resulting from the temperature pulse arising from each large energy deposition (greater than 200 keV) into the silicon frame around the array. The improved heat-sinking of the SXS array compared with XRS eliminated these thermal disturbances, greatly reducing the measured count rate in the absence of illumination. The removal of these events has made it easier to study the nature of the residual background and to look for additional event populations. We compare the SXS residual background to that measured in equivalent ground data for XRS and discuss these preliminary results.

  3. Acoustic invisibility cloaks of arbitrary shapes for complex background media

    NASA Astrophysics Data System (ADS)

    Zhu, Jian; Chen, Tianning; Liang, Qingxuan; Wang, Xiaopeng; Xiong, Jie; Jiang, Ping

    2016-04-01

    We report on the theoretical investigation of the acoustic cloaks working in complex background media in this paper. The constitutive parameters of arbitrary-shape cloaks are derived based on the transformation acoustic theory and coordinate transformation technique. The detailed analysis of boundaries conditions and potential applications of the cloaks are also presented in our work. To overcome the difficulty of achieving the materials with ideal parameters in nature, concentric alternating layered isotropic materials is adopted to approximate the required properties of the cloak. Theoretical design and excellent invisibility are demonstrated by numerical simulations. The inhomogeneous medium and arbitrary-shape acoustic cloaks grow closer to real application and may be a new hot spot in future.

  4. A field investigation on the effects of background erosion on the free span development of a submarine pipeline

    NASA Astrophysics Data System (ADS)

    Wen, Shipeng; Xu, Jishang; Hu, Guanghai; Dong, Ping; Shen, Hong

    2015-08-01

    The safety of submarine pipelines is largely influenced by free spans and corrosions. Previous studies on free spans caused by seabed scours are mainly based on the stable environment, where the background seabed scour is in equilibrium and the soil is homogeneous. To study the effects of background erosion on the free span development of subsea pipelines, a submarine pipeline located at the abandoned Yellow River subaqueous delta lobe was investigated with an integrated surveying system which included a Multibeam bathymetric system, a dual-frequency side-scan sonar, a high resolution sub-bottom profiler, and a Magnetic Flux Leakage (MFL) sensor. We found that seabed homogeneity has a great influence on the free span development of the pipeline. More specifically, for homogeneous background scours, the morphology of scour hole below the pipeline is quite similar to that without the background scour, whereas for inhomogeneous background scour, the nature of spanning is mainly dependent on the evolution of seabed morphology near the pipeline. Magnetic Flux Leakage (MFL) detection results also reveal the possible connection between long free spans and accelerated corrosion of the pipeline.

  5. 47 CFR 215.1 - Background.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Background. 215.1 Section 215.1 Telecommunication OFFICE OF SCIENCE AND TECHNOLOGY POLICY AND NATIONAL SECURITY COUNCIL FEDERAL GOVERNMENT FOCAL POINT FOR ELECTROMAGNETIC PULSE (EMP) INFORMATION § 215.1 Background. (a) The nuclear electromagnetic...

  6. 47 CFR 215.1 - Background.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Background. 215.1 Section 215.1 Telecommunication OFFICE OF SCIENCE AND TECHNOLOGY POLICY AND NATIONAL SECURITY COUNCIL FEDERAL GOVERNMENT FOCAL POINT FOR ELECTROMAGNETIC PULSE (EMP) INFORMATION § 215.1 Background. (a) The nuclear electromagnetic...

  7. 47 CFR 215.1 - Background.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Background. 215.1 Section 215.1 Telecommunication OFFICE OF SCIENCE AND TECHNOLOGY POLICY AND NATIONAL SECURITY COUNCIL FEDERAL GOVERNMENT FOCAL POINT FOR ELECTROMAGNETIC PULSE (EMP) INFORMATION § 215.1 Background. (a) The nuclear electromagnetic...

  8. 47 CFR 215.1 - Background.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Background. 215.1 Section 215.1 Telecommunication OFFICE OF SCIENCE AND TECHNOLOGY POLICY AND NATIONAL SECURITY COUNCIL FEDERAL GOVERNMENT FOCAL POINT FOR ELECTROMAGNETIC PULSE (EMP) INFORMATION § 215.1 Background. (a) The nuclear electromagnetic...

  9. 47 CFR 215.1 - Background.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Background. 215.1 Section 215.1 Telecommunication OFFICE OF SCIENCE AND TECHNOLOGY POLICY AND NATIONAL SECURITY COUNCIL FEDERAL GOVERNMENT FOCAL POINT FOR ELECTROMAGNETIC PULSE (EMP) INFORMATION § 215.1 Background. (a) The nuclear electromagnetic...

  10. 40 CFR 11.2 - Background.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 1 2010-07-01 2010-07-01 false Background. 11.2 Section 11.2 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY GENERAL SECURITY CLASSIFICATION REGULATIONS PURSUANT TO EXECUTIVE ORDER 11652 § 11.2 Background. While the Environmental Protection Agency does not...

  11. Extragalactic background light measurements and applications.

    PubMed

    Cooray, Asantha

    2016-03-01

    This review covers the measurements related to the extragalactic background light intensity from γ-rays to radio in the electromagnetic spectrum over 20 decades in wavelength. The cosmic microwave background (CMB) remains the best measured spectrum with an accuracy better than 1%. The measurements related to the cosmic optical background (COB), centred at 1 μm, are impacted by the large zodiacal light associated with interplanetary dust in the inner Solar System. The best measurements of COB come from an indirect technique involving γ-ray spectra of bright blazars with an absorption feature resulting from pair-production off of COB photons. The cosmic infrared background (CIB) peaking at around 100 μm established an energetically important background with an intensity comparable to the optical background. This discovery paved the way for large aperture far-infrared and sub-millimetre observations resulting in the discovery of dusty, starbursting galaxies. Their role in galaxy formation and evolution remains an active area of research in modern-day astrophysics. The extreme UV (EUV) background remains mostly unexplored and will be a challenge to measure due to the high Galactic background and absorption of extragalactic photons by the intergalactic medium at these EUV/soft X-ray energies. We also summarize our understanding of the spatial anisotropies and angular power spectra of intensity fluctuations. We motivate a precise direct measurement of the COB between 0.1 and 5 μm using a small aperture telescope observing either from the outer Solar System, at distances of 5 AU or more, or out of the ecliptic plane. Other future applications include improving our understanding of the background at TeV energies and spectral distortions of CMB and CIB.

  12. Extragalactic background light measurements and applications

    PubMed Central

    Cooray, Asantha

    2016-01-01

    This review covers the measurements related to the extragalactic background light intensity from γ-rays to radio in the electromagnetic spectrum over 20 decades in wavelength. The cosmic microwave background (CMB) remains the best measured spectrum with an accuracy better than 1%. The measurements related to the cosmic optical background (COB), centred at 1 μm, are impacted by the large zodiacal light associated with interplanetary dust in the inner Solar System. The best measurements of COB come from an indirect technique involving γ-ray spectra of bright blazars with an absorption feature resulting from pair-production off of COB photons. The cosmic infrared background (CIB) peaking at around 100 μm established an energetically important background with an intensity comparable to the optical background. This discovery paved the way for large aperture far-infrared and sub-millimetre observations resulting in the discovery of dusty, starbursting galaxies. Their role in galaxy formation and evolution remains an active area of research in modern-day astrophysics. The extreme UV (EUV) background remains mostly unexplored and will be a challenge to measure due to the high Galactic background and absorption of extragalactic photons by the intergalactic medium at these EUV/soft X-ray energies. We also summarize our understanding of the spatial anisotropies and angular power spectra of intensity fluctuations. We motivate a precise direct measurement of the COB between 0.1 and 5 μm using a small aperture telescope observing either from the outer Solar System, at distances of 5 AU or more, or out of the ecliptic plane. Other future applications include improving our understanding of the background at TeV energies and spectral distortions of CMB and CIB. PMID:27069645

  13. Intuitions about Origins: Purpose and Intelligent Design in Children's Reasoning about Nature

    ERIC Educational Resources Information Center

    Kelemen, Deborah; DiYanni, Cara

    2005-01-01

    Two separate bodies of research suggest that young children have (a) a broad tendency to reason about natural phenomena in terms of a purpose (e.g., Kelemen, 1999c) and (b) an orientation toward "creationist" accounts of natural entity origins whether or not they come from fundamentalist religious backgrounds (e.g., Evans, 2001). This…

  14. Developing an Instrument for Assessing Students' Concepts of the Nature of Technology

    ERIC Educational Resources Information Center

    Liou, Pey-Yan

    2015-01-01

    Background: The nature of technology has been rarely discussed despite the fact that technology plays an essential role in modern society. It is important to discuss students' concepts of the nature of technology, and further to advance their technological literacy and adaptation to modern society. There is a need to assess high school students'…

  15. Exceedance probability map: a tool helping the definition of arsenic Natural Background Level (NBL) within the Drainage Basin to the Venice Lagoon (NE Italy)

    NASA Astrophysics Data System (ADS)

    Dalla Libera, Nico; Fabbri, Paolo; Mason, Leonardo; Piccinini, Leonardo; Pola, Marco

    2017-04-01

    Arsenic groundwater contamination affects worldwide shallower groundwater bodies. Starting from the actual knowledges around arsenic origin into groundwater, we know that the major part of dissolved arsenic is naturally occurring through the dissolution of As-bearing minerals and ores. Several studies on the shallow aquifers of both the regional Venetian Plain (NE Italy) and the local Drainage Basin to the Venice Lagoon (DBVL) show local high arsenic concentration related to peculiar geochemical conditions, which drive arsenic mobilization. The uncertainty of arsenic spatial distribution makes difficult both the evaluation of the processes involved in arsenic mobilization and the stakeholders' decision about environmental management. Considering the latter aspect, the present study treats the problem of the Natural Background Level (NBL) definition as the threshold discriminating the natural contamination from the anthropogenic pollution. Actually, the UE's Directive 2006/118/EC suggests the procedures and criteria to set up the water quality standards guaranteeing a healthy status and reversing any contamination trends. In addition, the UE's BRIDGE project proposes some criteria, based on the 90th percentile of the contaminant's concentrations dataset, to estimate the NBL. Nevertheless, these methods provides just a statistical NBL for the whole area without considering the spatial variation of the contaminant's concentration. In this sense, we would reinforce the NBL concept using a geostatistical approach, which is able to give some detailed information about the distribution of arsenic concentrations and unveiling zones with high concentrations referred to the Italian drinking water standard (IDWS = 10 µg/liter). Once obtained the spatial information about arsenic distribution, we can apply the 90th percentile methods to estimate some Local NBL referring to every zones with arsenic higher than IDWS. The indicator kriging method was considered because it

  16. Detecting signatures of cosmological recombination and reionization in the cosmic radio background

    NASA Astrophysics Data System (ADS)

    Subrahmanyan, Ravi; Shankar Narayana Rao, Udaya; Sathyanarayana Rao, Mayuri; Singh, Saurabh

    2015-08-01

    Evolution of the baryons during the Epochs of cosmological Recombination and Reionization has left traces in the cosmic radio background in the form of spectral distortions (Sunyaev & Chluba 2008 Astron. Nachrichten, 330, 657; Pritchard & Loeb 2012 Rep Prog Phys 75(8):086901). The spectral signature depends on the evolution in the ionization state in hydrogen and helium and on the spin temperature of hydrogen. These probe the physics of energy release beyond the last scattering surface at redshifts exceeding 1090 and the nature of the first sources and gas evolution down to redshift about 6. The spectral distortions are sensitive to the nature of the first stars, ultra-dwarf galaxies, accreting compact objects, and the evolving ambient radiation field: X-rays and UV from the first sources. Detection of the all-sky or global spectral distortions in the radio background is hence a probe of cosmological recombination and reionization.We present new spectral radiometers that we have purpose designed for precision measurements of spectral distortions at radio wavelengths. New antenna elements include frequency independent and electrically small fat-dipole (Raghunathan et al. 2013 IEEE TAP, 61, 3411) and monopole designs. Receiver configurations have been devised that are self-calibratable (Patra et al. 2013 Expt Astron, 36, 319) so that switching of signal paths and of calibration noise sources provide real time calibration for systematics and receiver noise. Observing strategies (Patra et al. arXiv:1412.7762) and analysis methods (Satyanarayana Rao et al. arXiv:1501.07191) have been evolved that are capable of discriminating between the cosmological signals and the substantially brighter foregrounds. We have also demonstrated the value of system designs that exploit advantages of interferometer detection (Mahesh et al. arXiv:1406.2585) of global spectral distortions.Finally we discuss how the Square Kilometer Array stations may be outfitted with precision spectral

  17. Association of Radon Background and Total Background Ionizing Radiation with Alzheimer's Disease Deaths in U.S. States.

    PubMed

    Lehrer, Steven; Rheinstein, Peter H; Rosenzweig, Kenneth E

    2017-01-01

    Exposure of the brain to ionizing radiation might promote the development of Alzheimer's disease (AD). Analysis of AD death rates versus radon background radiation and total background radiation in U.S. states. Total background, radon background, cosmic and terrestrial background radiation measurements are from Assessment of Variations in Radiation Exposure in the United States and Report No. 160 - Ionizing Radiation Exposure of the Population of the United States. 2013 AD death rates by U.S. state are from the Alzheimer's Association. Radon background ionizing radiation was significantly correlated with AD death rate in 50 states and the District of Columbia (r = 0.467, p = 0.001). Total background ionizing radiation was also significantly correlated with AD death rate in 50 states and the District of Columbia (r = 0.452, p = 0.001). Multivariate linear regression weighted by state population demonstrated that AD death rate was significantly correlated with radon background (β= 0.169, p < 0.001), age (β= 0.231, p < 0.001), hypertension (β= 0.155, p < 0.001), and diabetes (β= 0.353, p < 0.001). Our findings, like other studies, suggest that ionizing radiation is a risk factor for AD. Intranasal inhalation of radon gas could subject the rhinencephalon and hippocampus to damaging radiation that initiates AD. The damage would accumulate over time, causing age to be a powerful risk factor.

  18. Ecological risk assessment: influence of texture on background concentration of microelements in soils of Russia.

    NASA Astrophysics Data System (ADS)

    Beketskaya, Olga

    2010-05-01

    In Russia quality standards of contaminated substances values in environment consist of ecological and sanitary rate-setting. The sanitary risk assessment base on potential risk that contaminants pose to protect human beings. The main purpose of the ecological risk assessment is to protect ecosystem. To determine negative influence on living organisms in the sanitary risk assessment in Russia we use MPC. This value of contaminants show how substances affected on different part of environment, biological activity and soil processes. The ecological risk assessment based on comparison compounds concentration with background concentration for definite territories. Taking into account high interval of microelements value in soils, we suggest using statistic method for determination of concentration levels of chemical elements concentration in soils of Russia. This method is based on determination middle levels of elements content in natural condition. The top limit of middle chemical elements concentration in soils is value, which exceed middle regional background level in three times standard deviation. The top limit of natural concentration excess we can explain as anthropogenic impact. At first we study changing in the middle content value of microelements in soils of geographic regions in European part of Russia on the basis of cartographical analysis. Cartographical analysis showed that the soil of mountainous and mountain surrounding regions is enriched with microelements. On the plain territory of European part of Russia for most of microelements was noticed general direction of increasing their concentration in soils from north to south, also in the same direction soil clay content rise for majority of soils. For all other territories a clear connection has been noticed between the distribution of sand sediment. By our own investigation and data from scientific literature data base was created. This data base consist of following soil properties: texture

  19. 47 CFR 201.0 - Background.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Background. 201.0 Section 201.0 Telecommunication OFFICE OF SCIENCE AND TECHNOLOGY POLICY AND NATIONAL SECURITY COUNCIL EXECUTIVE POLICY § 201.0 Background. National policy with respect to the conservation, allocation and use of the Nation's...

  20. 47 CFR 201.0 - Background.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Background. 201.0 Section 201.0 Telecommunication OFFICE OF SCIENCE AND TECHNOLOGY POLICY AND NATIONAL SECURITY COUNCIL EXECUTIVE POLICY § 201.0 Background. National policy with respect to the conservation, allocation and use of the Nation's...

  1. 47 CFR 201.0 - Background.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Background. 201.0 Section 201.0 Telecommunication OFFICE OF SCIENCE AND TECHNOLOGY POLICY AND NATIONAL SECURITY COUNCIL EXECUTIVE POLICY § 201.0 Background. National policy with respect to the conservation, allocation and use of the Nation's...

  2. 47 CFR 201.0 - Background.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Background. 201.0 Section 201.0 Telecommunication OFFICE OF SCIENCE AND TECHNOLOGY POLICY AND NATIONAL SECURITY COUNCIL EXECUTIVE POLICY § 201.0 Background. National policy with respect to the conservation, allocation and use of the Nation's...

  3. 47 CFR 201.0 - Background.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Background. 201.0 Section 201.0 Telecommunication OFFICE OF SCIENCE AND TECHNOLOGY POLICY AND NATIONAL SECURITY COUNCIL EXECUTIVE POLICY § 201.0 Background. National policy with respect to the conservation, allocation and use of the Nation's...

  4. 28 CFR 23.2 - Background.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 28 Judicial Administration 1 2011-07-01 2011-07-01 false Background. 23.2 Section 23.2 Judicial Administration DEPARTMENT OF JUSTICE CRIMINAL INTELLIGENCE SYSTEMS OPERATING POLICIES § 23.2 Background. It is... of intelligence data necessary to support control of serious criminal activity may represent...

  5. 28 CFR 23.2 - Background.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 28 Judicial Administration 1 2014-07-01 2014-07-01 false Background. 23.2 Section 23.2 Judicial Administration DEPARTMENT OF JUSTICE CRIMINAL INTELLIGENCE SYSTEMS OPERATING POLICIES § 23.2 Background. It is... of intelligence data necessary to support control of serious criminal activity may represent...

  6. 28 CFR 23.2 - Background.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 28 Judicial Administration 1 2013-07-01 2013-07-01 false Background. 23.2 Section 23.2 Judicial Administration DEPARTMENT OF JUSTICE CRIMINAL INTELLIGENCE SYSTEMS OPERATING POLICIES § 23.2 Background. It is... of intelligence data necessary to support control of serious criminal activity may represent...

  7. 28 CFR 23.2 - Background.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 28 Judicial Administration 1 2010-07-01 2010-07-01 false Background. 23.2 Section 23.2 Judicial Administration DEPARTMENT OF JUSTICE CRIMINAL INTELLIGENCE SYSTEMS OPERATING POLICIES § 23.2 Background. It is... of intelligence data necessary to support control of serious criminal activity may represent...

  8. 28 CFR 23.2 - Background.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 28 Judicial Administration 1 2012-07-01 2012-07-01 false Background. 23.2 Section 23.2 Judicial Administration DEPARTMENT OF JUSTICE CRIMINAL INTELLIGENCE SYSTEMS OPERATING POLICIES § 23.2 Background. It is... of intelligence data necessary to support control of serious criminal activity may represent...

  9. 47 CFR 32.1 - Background.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 2 2014-10-01 2014-10-01 false Background. 32.1 Section 32.1 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES UNIFORM SYSTEM OF ACCOUNTS FOR TELECOMMUNICATIONS COMPANIES Preface § 32.1 Background. The revised Uniform System of Accounts (USOA) is a historical...

  10. 47 CFR 32.1 - Background.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 2 2013-10-01 2013-10-01 false Background. 32.1 Section 32.1 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES UNIFORM SYSTEM OF ACCOUNTS FOR TELECOMMUNICATIONS COMPANIES Preface § 32.1 Background. The revised Uniform System of Accounts (USOA) is a historical...

  11. 47 CFR 32.1 - Background.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 2 2011-10-01 2011-10-01 false Background. 32.1 Section 32.1 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES UNIFORM SYSTEM OF ACCOUNTS FOR TELECOMMUNICATIONS COMPANIES Preface § 32.1 Background. The revised Uniform System of Accounts (USOA) is a historical...

  12. CALDER: Cryogenic light detectors for background-free searches

    NASA Astrophysics Data System (ADS)

    Di Domizio, S.; Bellini, F.; Cardani, L.; Casali, N.; Castellano, M. G.; Colantoni, I.; Cosmelli, C.; Cruciani, A.; D'Addabbo, A.; Martinez, M.; Minutolo, L.; Tomei, C.; Vignati, M.

    2018-01-01

    CALDER is a R&D project for the development of cryogenic light detectors with an active surface of 5x5cm2 and an energy resolution of 20 eV RMS for visible and UV photons. These devices can enhance the sensitivity of next generation large mass bolometric detectors for rare event searches, providing an active background rejection method based on particle discrimination. A CALDER detector is composed by a large area Si absorber substrate with superconducting kinetic inductance detectors (KIDs) deposited on it. The substrate converts the incoming light into athermal phonons, that are then sensed by the KIDs. KID technology combine fabrication simplicity with natural attitude to frequency-domain multiplexing, making it an ideal candidate for a large scale bolometric experiments. We will give an overview of the CALDER project and show the performances obtained with prototype detectors both in terms of energy resolution and efficiency.

  13. 32 CFR 1292.3 - Background.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 32 National Defense 6 2010-07-01 2010-07-01 false Background. 1292.3 Section 1292.3 National Defense Other Regulations Relating to National Defense DEFENSE LOGISTICS AGENCY MISCELLANEOUS SECURITY OF DLA ACTIVITIES AND RESOURCES § 1292.3 Background. Section 21 of the Internal Security Act of 1950...

  14. 14 CFR 1214.302 - Background.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 5 2012-01-01 2012-01-01 false Background. 1214.302 Section 1214.302 Aeronautics and Space NATIONAL AERONAUTICS AND SPACE ADMINISTRATION SPACE FLIGHT Payload Specialists for Space Transportation System (STS) Missions § 1214.302 Background. (a) The Space Transportation System (STS) has been...

  15. 14 CFR 1214.302 - Background.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 5 2010-01-01 2010-01-01 false Background. 1214.302 Section 1214.302 Aeronautics and Space NATIONAL AERONAUTICS AND SPACE ADMINISTRATION SPACE FLIGHT Payload Specialists for Space Transportation System (STS) Missions § 1214.302 Background. (a) The Space Transportation System (STS) has been...

  16. 14 CFR 1214.302 - Background.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 5 2011-01-01 2010-01-01 true Background. 1214.302 Section 1214.302 Aeronautics and Space NATIONAL AERONAUTICS AND SPACE ADMINISTRATION SPACE FLIGHT Payload Specialists for Space Transportation System (STS) Missions § 1214.302 Background. (a) The Space Transportation System (STS) has been...

  17. 14 CFR 1214.302 - Background.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 5 2013-01-01 2013-01-01 false Background. 1214.302 Section 1214.302 Aeronautics and Space NATIONAL AERONAUTICS AND SPACE ADMINISTRATION SPACE FLIGHT Payload Specialists for Space Transportation System (STS) Missions § 1214.302 Background. (a) The Space Transportation System (STS) has been...

  18. 32 CFR 1292.3 - Background.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 32 National Defense 6 2012-07-01 2012-07-01 false Background. 1292.3 Section 1292.3 National Defense Other Regulations Relating to National Defense DEFENSE LOGISTICS AGENCY MISCELLANEOUS SECURITY OF DLA ACTIVITIES AND RESOURCES § 1292.3 Background. Section 21 of the Internal Security Act of 1950...

  19. 32 CFR 1292.3 - Background.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 32 National Defense 6 2011-07-01 2011-07-01 false Background. 1292.3 Section 1292.3 National Defense Other Regulations Relating to National Defense DEFENSE LOGISTICS AGENCY MISCELLANEOUS SECURITY OF DLA ACTIVITIES AND RESOURCES § 1292.3 Background. Section 21 of the Internal Security Act of 1950...

  20. 32 CFR 1292.3 - Background.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 32 National Defense 6 2013-07-01 2013-07-01 false Background. 1292.3 Section 1292.3 National Defense Other Regulations Relating to National Defense DEFENSE LOGISTICS AGENCY MISCELLANEOUS SECURITY OF DLA ACTIVITIES AND RESOURCES § 1292.3 Background. Section 21 of the Internal Security Act of 1950...

  1. 32 CFR 1292.3 - Background.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 32 National Defense 6 2014-07-01 2014-07-01 false Background. 1292.3 Section 1292.3 National Defense Other Regulations Relating to National Defense DEFENSE LOGISTICS AGENCY MISCELLANEOUS SECURITY OF DLA ACTIVITIES AND RESOURCES § 1292.3 Background. Section 21 of the Internal Security Act of 1950...

  2. 32 CFR 3.2 - Background.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 32 National Defense 1 2010-07-01 2010-07-01 false Background. 3.2 Section 3.2 National Defense Department of Defense OFFICE OF THE SECRETARY OF DEFENSE ACQUISITION TRANSACTIONS OTHER THAN CONTRACTS, GRANTS, OR COOPERATIVE AGREEMENTS FOR PROTOTYPE PROJECTS § 3.2 Background. “Other transactions” is the...

  3. Non-associativity in non-geometric string and M-theory backgrounds, the algebra of octonions, and missing momentum modes

    DOE PAGES

    Günaydin, Murat; Lüst, Dieter; Malek, Emanuel

    2016-11-07

    We propose a non-associative phase space algebra for M-theory backgrounds with locally non-geometric fluxes based on the non-associative algebra of octonions. Our proposal is based on the observation that the non-associative algebra of the non-geometric R-flux background in string theory can be obtained by a proper contraction of the simple Malcev algebra generated by imaginary octonions. Furthermore, by studying a toy model of a four-dimensional locally non-geometric M-theory background which is dual to a twisted torus, we show that the non-geometric background is “missing” a momentum mode. The resulting seven-dimensional phase space can thus be naturally identified with the imaginarymore » octonions. This allows us to interpret the full uncontracted algebra of imaginary octonions as the uplift of the string theory R-flux algebra to M-theory, with the contraction parameter playing the role of the string coupling constant g s.« less

  4. Non-associativity in non-geometric string and M-theory backgrounds, the algebra of octonions, and missing momentum modes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Günaydin, Murat; Lüst, Dieter; Malek, Emanuel

    We propose a non-associative phase space algebra for M-theory backgrounds with locally non-geometric fluxes based on the non-associative algebra of octonions. Our proposal is based on the observation that the non-associative algebra of the non-geometric R-flux background in string theory can be obtained by a proper contraction of the simple Malcev algebra generated by imaginary octonions. Furthermore, by studying a toy model of a four-dimensional locally non-geometric M-theory background which is dual to a twisted torus, we show that the non-geometric background is “missing” a momentum mode. The resulting seven-dimensional phase space can thus be naturally identified with the imaginarymore » octonions. This allows us to interpret the full uncontracted algebra of imaginary octonions as the uplift of the string theory R-flux algebra to M-theory, with the contraction parameter playing the role of the string coupling constant g s.« less

  5. Level-Dependent Nonlinear Hearing Protector Model in the Auditory Hazard Assessment Algorithm for Humans

    DTIC Science & Technology

    2015-04-01

    9 Fig. 8 Resistance of orifice flow plotted vs. flow velocity. Acoustic ohm units are dynes∙s∙cm5; the changing resistance demonstrates the...process of nonlinear flow through the orifice. (The blue single-orifice fit and the red total resistance for a dual orifice configuration were added...piston hearing protection model with level- dependent extensions in cushion visco-elastic elements and leakage flow impedance

  6. 32 CFR 763.3 - Background.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 32 National Defense 5 2010-07-01 2010-07-01 false Background. 763.3 Section 763.3 National Defense Department of Defense (Continued) DEPARTMENT OF THE NAVY ISLANDS UNDER NAVY JURISDICTION RULES GOVERNING PUBLIC ACCESS Entry Regulations for Kaho'olawe Island, Hawaii § 763.3 Background. (a) Kaho'olawe Island...

  7. 32 CFR 735.2 - Background.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 32 National Defense 5 2011-07-01 2011-07-01 false Background. 735.2 Section 735.2 National Defense Department of Defense (Continued) DEPARTMENT OF THE NAVY PERSONNEL REPORTING BIRTHS AND DEATHS IN COOPERATION WITH OTHER AGENCIES § 735.2 Background. For Armed Forces members and their dependents on duty overseas...

  8. 32 CFR 735.2 - Background.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 32 National Defense 5 2010-07-01 2010-07-01 false Background. 735.2 Section 735.2 National Defense Department of Defense (Continued) DEPARTMENT OF THE NAVY PERSONNEL REPORTING BIRTHS AND DEATHS IN COOPERATION WITH OTHER AGENCIES § 735.2 Background. For Armed Forces members and their dependents on duty overseas...

  9. Nature Contact and Human Health: A Research Agenda

    PubMed Central

    Bratman, Gregory N.; Breslow, Sara Jo; Cochran, Bobby; Kahn Jr, Peter H.; Lawler, Joshua J.; Levin, Phillip S.; Tandon, Pooja S.; Varanasi, Usha; Wolf, Kathleen L.; Wood, Spencer A.

    2017-01-01

    Background: At a time of increasing disconnectedness from nature, scientific interest in the potential health benefits of nature contact has grown. Research in recent decades has yielded substantial evidence, but large gaps remain in our understanding. Objectives: We propose a research agenda on nature contact and health, identifying principal domains of research and key questions that, if answered, would provide the basis for evidence-based public health interventions. Discussion: We identify research questions in seven domains: a) mechanistic biomedical studies; b) exposure science; c) epidemiology of health benefits; d) diversity and equity considerations; e) technological nature; f) economic and policy studies; and g) implementation science. Conclusions: Nature contact may offer a range of human health benefits. Although much evidence is already available, much remains unknown. A robust research effort, guided by a focus on key unanswered questions, has the potential to yield high-impact, consequential public health insights. https://doi.org/10.1289/EHP1663 PMID:28796634

  10. Aircraft and background noise annoyance effects

    NASA Technical Reports Server (NTRS)

    Willshire, K. F.

    1984-01-01

    To investigate annoyance of multiple noise sources, two experiments were conducted. The first experiment, which used 48 subjects, was designed to establish annoyance-noise level functions for three community noise sources presented individually: jet aircraft flyovers, air conditioner, and traffic. The second experiment, which used 216 subjects, investigated the effects of background noise on aircraft annoyance as a function of noise level and spectrum shape; and the differences between overall, aircraft, and background noise annoyance. In both experiments, rated annoyance was the dependent measure. Results indicate that the slope of the linear relationship between annoyance and noise level for traffic is significantly different from that of flyover and air conditioner noise and that further research was justified to determine the influence of the two background noises on overall, aircraft, and background noise annoyance (e.g., experiment two). In experiment two, total noise exposure, signal-to-noise ratio, and background source type were found to have effects on all three types of annoyance. Thus, both signal-to-noise ratio, and the background source must be considered when trying to determine community response to combined noise sources.

  11. Compression ignition engine having fuel system for non-sooting combustion and method

    DOEpatents

    Bazyn, Timothy; Gehrke, Christopher

    2014-10-28

    A direct injection compression ignition internal combustion engine includes a fuel system having a nozzle extending into a cylinder of the engine and a plurality of spray orifices formed in the nozzle. Each of the spray orifices has an inner diameter dimension of about 0.09 mm or less, and define inter-orifice angles between adjacent spray orifice center axes of about 36.degree. or greater such that spray plumes of injected fuel from each of the spray orifices combust within the cylinder according to a non-sooting lifted flame and gas entrainment combustion pattern. Related methodology is also disclosed.

  12. The impact of loupes and microscopes on vision in endodontics.

    PubMed

    Perrin, P; Neuhaus, K W; Lussi, A

    2014-05-01

    To report on an intraradicular visual test in a simulated clinical setting under different optical conditions. Miniaturized visual tests with E-optotypes (bar distance from 0.01 to 0.05 mm) were fixed inside the root canal system of an extracted maxillary molar at different locations: at the orifice, a depth of 5 mm and the apex. The tooth was mounted in a phantom head for a simulated clinical setting. Unaided vision was compared with Galilean loupes (2.5× magnification) with integrated light source and an operating microscope (6× magnification). The influence of the dentists' age within two groups was evaluated: <40 years (n = 9) and ≥40 years (n = 15). Some younger dentists were able to identify the E-optotypes at the orifice, but otherwise, natural vision did not reveal any measurable result. With Galilean loupes, the younger dentists <40 years could see a 0.05 mm structure at the root canal orifice, in contrast to the older group ≥40 years. Only the microscope allowed the observation of structures inside the root canal, independent of age. Unaided vision and Galilean loupes with an integrated light source could not provide any measurable vision inside the root canal, but younger dentists <40 years could detect with Galilean loupes a canal orifice corresponding to the tip of the smallest endodontic instruments. Dentists over 40 years of age were dependent on the microscope to inspect the root canal system. © 2013 International Endodontic Journal. Published by John Wiley & Sons Ltd.

  13. Inferring the background traffic arrival process in the Internet.

    PubMed

    Hága, Péter; Csabai, István; Vattay, Gábor

    2009-12-01

    Phase transition has been found in many complex interactivity systems. Complex networks are not exception either but there are quite few real systems where we can directly understand the emergence of this nontrivial behavior from the microscopic view. In this paper, we present the emergence of the phase transition between the congested and uncongested phases of a network link. We demonstrate a method to infer the background traffic arrival process, which is one of the key state parameters of the Internet traffic. The traffic arrival process in the Internet has been investigated in several studies, since the recognition of its self-similar nature. The statistical properties of the traffic arrival process are very important since they are fundamental in modeling the dynamical behavior. Here, we demonstrate how the widely used packet train technique can be used to determine the main properties of the traffic arrival process. We show that the packet train dispersion is sensitive to the congestion on the network path. We introduce the packet train stretch as an order parameter to describe the phase transition between the congested and uncongested phases of the bottleneck link in the path. We find that the distribution of the background traffic arrival process can be determined from the average packet train dispersion at the critical point of the system.

  14. Assessment of ambient background concentrations of elements in soil using combined survey and open-source data.

    PubMed

    Mikkonen, Hannah G; Clarke, Bradley O; Dasika, Raghava; Wallis, Christian J; Reichman, Suzie M

    2017-02-15

    Understanding ambient background concentrations in soil, at a local scale, is an essential part of environmental risk assessment. Where high resolution geochemical soil surveys have not been undertaken, soil data from alternative sources, such as environmental site assessment reports, can be used to support an understanding of ambient background conditions. Concentrations of metals/metalloids (As, Mn, Ni, Pb and Zn) were extracted from open-source environmental site assessment reports, for soils derived from the Newer Volcanics basalt, of Melbourne, Victoria, Australia. A manual screening method was applied to remove samples that were indicated to be contaminated by point sources and hence not representative of ambient background conditions. The manual screening approach was validated by comparison to data from a targeted background soil survey. Statistical methods for exclusion of contaminated samples from background soil datasets were compared to the manual screening method. The statistical methods tested included the Median plus Two Median Absolute Deviations, the upper whisker of a normal and log transformed Tukey boxplot, the point of inflection on a cumulative frequency plot and the 95th percentile. We have demonstrated that where anomalous sample results cannot be screened using site information, the Median plus Two Median Absolute Deviations is a conservative method for derivation of ambient background upper concentration limits (i.e. expected maximums). The upper whisker of a boxplot and the point of inflection on a cumulative frequency plot, were also considered adequate methods for deriving ambient background upper concentration limits, where the percentage of contaminated samples is <25%. Median ambient background concentrations of metals/metalloids in the Newer Volcanic soils of Melbourne were comparable to ambient background concentrations in Europe and the United States, except for Ni, which was naturally enriched in the basalt-derived soils of

  15. Exploratory and spatial data analysis (EDA-SDA) for determining regional background levels and anomalies of potentially toxic elements in soils from Catorce-Matehuala, Mexico

    USGS Publications Warehouse

    Chiprés, J.A.; Castro-Larragoitia, J.; Monroy, M.G.

    2009-01-01

    The threshold between geochemical background and anomalies can be influenced by the methodology selected for its estimation. Environmental evaluations, particularly those conducted in mineralized areas, must consider this when trying to determinate the natural geochemical status of a study area, quantifying human impacts, or establishing soil restoration values for contaminated sites. Some methods in environmental geochemistry incorporate the premise that anomalies (natural or anthropogenic) and background data are characterized by their own probabilistic distributions. One of these methods uses exploratory data analysis (EDA) on regional geochemical data sets coupled with a geographic information system (GIS) to spatially understand the processes that influence the geochemical landscape in a technique that can be called a spatial data analysis (SDA). This EDA-SDA methodology was used to establish the regional background range from the area of Catorce-Matehuala in north-central Mexico. Probability plots of the data, particularly for those areas affected by human activities, show that the regional geochemical background population is composed of smaller subpopulations associated with factors such as soil type and parent material. This paper demonstrates that the EDA-SDA method offers more certainty in defining thresholds between geochemical background and anomaly than a numeric technique, making it a useful tool for regional geochemical landscape analysis and environmental geochemistry studies.

  16. Experimental investigations into the nature of airflows near Bluff bodies with aspiration, with implications to aerosol sampling

    NASA Astrophysics Data System (ADS)

    Sreenath, Avula; Ramachandran, Gurumurthy; Vincent, James H.

    The research described in this paper was stimulated by the need to understand better the nature of air flow around aerosol samplers of the type widely used in environmental and industrial hygiene. It deals with the application of visualisation techniques to determine the location of stagnation points for air flow about simple two- and three-dimensional bluff bodies (cylinder and sphere, respectively) for the case where there is aspiration of air (i.e. suction) from a point on the body surface. The effect of orientation of the sampling orifice (or sink) with respect to the free stream on the location of stagnation points was compared with theoretical predictions using potential flow models. Good agreement was obtained, even for large angles with respect to the wind. For the two-dimensional cylindrical body, we also experimentally investigated the frequency of the vortex shedding in its near wake and how that is influenced by the aspiration. As represented by the dimensionless Strouhal number, this was found to be strongly dependent on the aspiration flow rate and the slot orientation. The results may be explained qualitatively in terms of the effect of aspiration on the development of the boundary layer over the cylinder surface.

  17. 32 CFR 732.1 - Background.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 32 National Defense 5 2010-07-01 2010-07-01 false Background. 732.1 Section 732.1 National Defense Department of Defense (Continued) DEPARTMENT OF THE NAVY PERSONNEL NONNAVAL MEDICAL AND DENTAL CARE General § 732.1 Background. When a U.S. Navy or Marine Corps member or a Canadian Navy or Marine Corps member...

  18. 32 CFR 732.1 - Background.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 32 National Defense 5 2013-07-01 2013-07-01 false Background. 732.1 Section 732.1 National Defense Department of Defense (Continued) DEPARTMENT OF THE NAVY PERSONNEL NONNAVAL MEDICAL AND DENTAL CARE General § 732.1 Background. When a U.S. Navy or Marine Corps member or a Canadian Navy or Marine Corps member...

  19. 32 CFR 732.1 - Background.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 32 National Defense 5 2014-07-01 2014-07-01 false Background. 732.1 Section 732.1 National Defense Department of Defense (Continued) DEPARTMENT OF THE NAVY PERSONNEL NONNAVAL MEDICAL AND DENTAL CARE General § 732.1 Background. When a U.S. Navy or Marine Corps member or a Canadian Navy or Marine Corps member...

  20. 32 CFR 732.1 - Background.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 32 National Defense 5 2011-07-01 2011-07-01 false Background. 732.1 Section 732.1 National Defense Department of Defense (Continued) DEPARTMENT OF THE NAVY PERSONNEL NONNAVAL MEDICAL AND DENTAL CARE General § 732.1 Background. When a U.S. Navy or Marine Corps member or a Canadian Navy or Marine Corps member...