Cerebral Arterial Occlusion Did Not Promote the Prevalence of Cerebral Amyloid Angiopathy.

PubMed

Honda, Kazuhiro

2016-08-01

An impairment of amyloid-β (Aβ) clearance has been suggested in Alzheimer's disease. Perivascular drainage along cerebrovascular vessels is considered an important amyloid clearance pathway. This study examined the effect of reduced arterial pulsation that could cause an impairment in cerebral amyloid drainage on the prevalence of cortical microbleeds (CMBs), a surrogate marker for cerebral amyloid angiopathy (CAA). Patients who lost depiction of either side of the carotid artery or the middle cerebral artery on magnetic resonance angiography were studied. Those who showed acute cerebral infarction or a previous cortical cerebral infarction were excluded. The number of CMBs was counted on the occluded and non-occluded sides of the brain in each subject. The number of subjects who showed more CMBs on the occluded side of the brain was compared with the number of subjects who showed more CMBs on the non-occluded side of the brain. Twenty-eight patients were studied. The extent of lacunar infarction and white matter lesions was not different, irrespective of the occluded vessels or the distribution of CMBs. The prevalence of CMBs was not different between the occluded and non-occluded sides of the brain. In this cross-sectional study, reduction of arterial pulsation was not associated with a higher prevalence of CAA. Therefore, reduced arterial pulsation alone may not be enough to promote CAA.

Investigation of Local Hydrogen Uptake in Rescaled Model Occluded Sites Using Crevice Scaling Laws

DTIC Science & Technology

2005-04-01

13- 8 Mo . Under anodic polarization, there is a combination of x and G in a crevice or crack where the stainless steel would be passive and remain...2004). 8 . G.A. Young, Jr., J.R. Scully, "The Effects of Test Temperature , Temper and Alloyed Copper on Hydrogen Controlled Crack Growth of an A1-Zn-Mg...sharp crack tip.[16] Precipitation-aged hardened martensitic stainless steels (i.e., Fe-Cr-Ni- Mo alloys) that release hydrolysable Cr and Fe cations

Transjugular Intrahepatic Portosystemic Shunt Placement in Patients with Cirrhosis and Concomitant Portal Vein Thrombosis

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

Ha, Thuong G. Van, E-mail: tgvanha@radiology.bsd.uchicago.edu; Hodge, Justin; Funaki, Brian

2006-10-15

Purpose. To determine the safety and efficacy of transjugular intrahepatic portosystemic shunt (TIPS) creation in patients with liver cirrhosis complicated by thrombosed portal vein. Methods. This study reviewed 15 cases of TIPS creation in 15 cirrhotic patients with portal vein thrombosis at our institution over an 8-year period. There were 2 women and 13 men with a mean age of 53 years. Indications were refractory ascites, variceal hemorrhage, and refractory pleural effusion. Clinical follow-up was performed in all patients. Results. The technical success rate was 75% (3/4) in patients with chronic portal vein thrombosis associated with cavernomatous transformation and 91%more » (10/11) in patients with acute thrombosis or partial thrombosis, giving an overall success rate of 87%. Complications included postprocedural encephalopathy and localized hematoma at the access site. In patients with successful shunt placement, the total follow-up time was 223 months. The 30-day mortality rate was 13%. Two patients underwent liver transplantation at 35 days and 7 months, respectively, after TIPS insertion. One patient had an occluded shunt at 4 months with an unsuccessful revision. The remaining patients had functioning shunts at follow-up. Conclusion. TIPS creation in thrombosed portal vein is possible and might be a treatment option in certain patients.« less

Corrosion fatigue crack propagation in metals

NASA Technical Reports Server (NTRS)

Gangloff, Richard P.

1990-01-01

This review assesses fracture mechanics data and mechanistic models for corrosion fatigue crack propagation in structural alloys exposed to ambient temperature gases and electrolytes. Extensive stress intensity-crack growth rate data exist for ferrous, aluminum and nickel based alloys in a variety of environments. Interactive variables (viz., stress intensity range, mean stress, alloy composition and microstructure, loading frequency, temperature, gas pressure and electrode potential) strongly affect crack growth kinetics and complicate fatigue control. Mechanistic models to predict crack growth rates were formulated by coupling crack tip mechanics with occluded crack chemistry, and from both the hydrogen embrittlement and anodic dissolution/film rupture perspectives. Research is required to better define: (1) environmental effects near threshold and on crack closure; (2) damage tolerant life prediction codes and the validity of similitude; (3) the behavior of microcrack; (4) probes and improved models of crack tip damage; and (5) the cracking performance of advanced alloys and composites.

Efficacy of a Dexamethasone-Eluting Nitinol Stent on the Inhibition of Pseudointimal Hyperplasia in a Transjugular Intrahepatic Portosystemic Shunt: An Experimental Study in a Swine Model

PubMed Central

Seo, Tae-Seok; Park, Young-Koo; Song, Ho-Young; Park, Sang Joon; Yuk, Sun-Hong

2005-01-01

Objective We wanted to evaluate the feasibility and efficacy of using a dexamethasone (DM)-eluting nitinol stent to inhibit the pseudointimal hyperplasia following stent placement in the transjugular intrahepatic portosystemic shunt tract (TIPS) of a swine. Materials and Methods Fifteen stents were constructed using 0.15 mm-thick nitinol wire; they were 60 mm in length and 10 mm in diameter. The metallic stents were then classified into three types; type 1 and 2 was coated with the mixture of 12% and 20%, respectively, of DM solution and polyurethane (PU), while type 3 was a bare stent that was used for control study. In fifteen swine, each type of stent was implanted in the TIPS tract of 5 swine, and each animal was sacrificed 2 weeks after TIPS creation. The proliferation of the pseudointima was evaluated both on follow-up portogram and pathologic examination. Results One TIPS case, using the type 1 stent, and two TIPS cases, using the type 2 stent, maintained their luminal patency while the others were all occluded. On the histopathologic analysis, the mean of the maximum pseudointimal hyperplasia was expressed as the percentage of the stent radius that was patent, and these values were 51.2%, 50% and 76% for the type 1, 2, and 3 stents, respectively. Conclusion The DM-eluting stent showed a tendency to reduce the development of pseudointimal hyperplasia in the TIPS tract of a swine model with induced-portal hypertension. PMID:16374082

Time course of spatial and feature selective attention for partly-occluded objects.

PubMed

Kasai, Tetsuko; Takeya, Ryuji

2012-07-01

Attention selects objects/groups as the most fundamental units, and this may be achieved by an attention-spreading mechanism. Previous event-related potential (ERP) studies have found that attention-spreading is reflected by a decrease in the N1 spatial attention effect. The present study tested whether the electrophysiological attention effect is associated with the perception of object unity or amodal completion through the use of partly-occluded objects. ERPs were recorded in 14 participants who were required to pay attention to their left or right visual field and to press a button for a target shape in the attended field. Bilateral stimuli were presented rapidly, and were separated, connected, or connected behind an occluder. Behavioral performance in the connected and occluded conditions was worse than that in the separated condition, indicating that attention spread over perceptual object representations after amodal completion. Consistently, the late N1 spatial attention effect (180-220 ms post-stimulus) and the early phase (230-280 ms) of feature selection effects (target N2) at contralateral sites decreased, equally for the occluded and connected conditions, while the attention effect in the early N1 latency (140-180 ms) shifted most positively for the occluded condition. These results suggest that perceptual organization processes for object recognition transiently modulate spatial and feature selection processes in the visual cortex. Copyright © 2012 Elsevier Ltd. All rights reserved.

Computational evaluation of aortic occlusion and the proposal of a novel, improved occluder: Constrained endo-aortic balloon occlusion.

PubMed

de Vaal, M H; Gee, M W; Stock, U A; Wall, W A

2016-12-01

Because aortic occlusion is arguably one of the most dangerous aortic manipulation maneuvers during cardiac surgery in terms of perioperative ischemic neurological injury, the purpose of this investigation is to assess the structural mechanical impact resulting from the use of existing and newly proposed occluders. Existing (clinically used) occluders considered include different cross-clamps (CCs) and endo-aortic balloon occlusion (EABO). A novel occluder is also introduced, namely, constrained EABO (CEABO), which consists of applying a constrainer externally around the aorta when performing EABO. Computational solid mechanics are employed to investigate each occluder according to a comprehensive list of functional requirements. The potential of a state of occlusion is also considered for the first time. Three different constrainer designs are evaluated for CEABO. Although the CCs were responsible for the highest strains, largest deformation, and most inefficient increase of the occlusion potential, it remains the most stable, simplest, and cheapest occluder. The different CC hinge geometries resulted in poorer performance of CC used for minimally invasive procedures than conventional ones. CEABO with a profiled constrainer successfully addresses the EABO shortcomings of safety, stability, and positioning accuracy, while maintaining its complexities of operation (disadvantage) and yielding additional functionalities (advantage). Moreover, CEABO is able to achieve the previously unattainable potential to provide a clinically determinable state of occlusion. CEABO offers an attractive alternative to the shortcomings of existing occluders, with its design rooted in achieving the highest patient safety. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Visible and invisible displacement with dynamic visual occlusion in bottlenose dolphins (Tursiops spp).

PubMed

Johnson, Christine M; Sullivan, Jess; Buck, Cara L; Trexel, Julie; Scarpuzzi, Mike

2015-01-01

Anticipating the location of a temporarily obscured target-what Piaget (the construction of reality in the child. Basic Books, New York, 1954) called "object permanence"-is a critical skill, especially in hunters of mobile prey. Previous research with bottlenose dolphins found they could predict the location of a target that had been visibly displaced into an opaque container, but not one that was first placed in an opaque container and then invisibly displaced to another container. We tested whether, by altering the task to involve occlusion rather than containment, these animals could show more advanced object permanence skills. We projected dynamic visual displays at an underwater-viewing window and videotaped the animals' head moves while observing these displays. In Experiment 1, the animals observed a small black disk moving behind occluders that shifted in size, ultimately forming one large occluder. Nine out of ten subjects "tracked" the presumed movement of the disk behind this occluder on their first trial-and in a statistically significant number of subsequent trials-confirming their visible displacement abilities. In Experiment 2, we tested their invisible displacement abilities. The disk first disappeared behind a pair of moving occluders, which then moved behind a stationary occluder. The moving occluders then reappeared and separated, revealing that the disk was no longer behind them. The subjects subsequently looked to the correct stationary occluder on eight of their ten first trials, and in a statistically significant number of subsequent trials. Thus, by altering the stimuli to be more ecologically valid, we were able to show that the dolphins could indeed succeed at an invisible displacement task.

Transjugular Intrahepatic Portosystemic Shunt Creation and Variceal Coil or Plug Embolization Ineffectively Attain Gastric Variceal Decompression or Occlusion: Results of a 26-Patient Retrospective Study.

PubMed

Lakhoo, Janesh; Bui, James T; Lokken, R Peter; Ray, Charles E; Gaba, Ron C

2016-07-01

To assess the efficacy of transjugular intrahepatic portosystemic shunt (TIPS) creation with or without variceal coil and/or plug embolization in decompressing or occluding gastric varices (GVs). In this retrospective study, 78 patients with GV bleeding who underwent TIPS creation with or without embolotherapy with metallic coils and/or plugs from 1999 to 2014 were identified. Individuals who had a bare-metal TIPS and/or lacked post-TIPS imaging or endoscopic follow-up were excluded. The final cohort included 26 patients (16 men; median age, 54 y; median Model for End-stage Liver Disease score, 16). Variceal types, supplying vessels, and postprocedure GV patency on cross-sectional imaging or endoscopy were assessed. The primary study outcome measure was GV patency rate as a surrogate for efficacy of TIPS creation with or without embolization. GVs included gastroesophageal varix types 1 (n = 10) and 2 (n = 2), isolated GV types 1 (n = 4) and 2 (n = 2), and unspecified (n = 8). TIPS creation resulted in a median final portosystemic pressure gradient of 7 mm Hg. Multiple GV-supplying vessels (left/posterior/short gastric veins) were present in 65% of patients (n = 17). Embolization was performed in 69% (n = 18). Thirteen, four, and nine patients had imaging, endoscopic, or both imaging/endoscopic follow-up. GV patency rate was 65% (n = 17; 61%/75% with/without embolization) at a median of 128.5 days (range, 1-1,295 d) after TIPS creation. Incidence of recurrent bleeding was 27% (n = 7), and the 90-day mortality rate was 15% (n = 4). In this study, most GVs showed persistent patency despite TIPS decompression and variceal embolization, and the incidence of recurrent bleeding was high. The findings suggest suboptimal efficacy for GVs, and indicate a need for study of alternative or adjunctive approaches to GV treatment, such as chemical obliteration. Copyright © 2016 SIR. Published by Elsevier Inc. All rights reserved.

Efficacy of a Creon delayed-release pancreatic enzyme protocol for clearing occluded enteral feeding tubes.

PubMed

Stumpf, Janice L; Kurian, Rebecca M; Vuong, Jennifer; Dang, Kimberlyn; Kraft, Michael D

2014-04-01

Alkalinized Viokase pancreatic enzyme tablets restored patency to 71.9% of occluded Dobhoff tubes in a prospective study. After removal of Viokase tablets from the US market, the hospital protocol for unclogging enteral feeding tubes was adapted to use Creon pancreatic enzyme delayed-release capsules, despite the lack of published data. To evaluate the effectiveness of a Creon-based protocol to clear occluded enteral feeding tubes. This retrospective study included all adult and pediatric patients seen in the emergency department or in an inpatient setting who received Creon 12 000 units lipase delayed-release capsule dissolved in a solution of sodium bicarbonate 650 mg and sterile water for clearing occluded enteral feeding tubes between May 1 and November 30, 2010. The Creon protocol was deemed effective if tube clearance was documented in the medical record or if enteral feedings were resumed with no note regarding tube replacement. Alkalinized Creon delayed-release capsules were administered to 83 patients with a total of 118 clogged tubes. Three poorly documented cases and 5 tubes with mechanical clogs were excluded from data analysis. Patency was restored to 53 of 110 (48.2%) occluded tubes. More than 1 treatment course was attempted in 5 cases, with success in 3. An alkalinized Creon pancreatic enzyme protocol was effective in clearing approximately half of the occluded enteral feeding tubes in this retrospective study, an efficacy rate much less than that previously reported in the literature with a Viokase-based protocol.

A retrospective comparative study of tunneled haemodialysis catheters inserted through occluded or collateral veins versus conventional methods.

PubMed

Powell, Steven; Chan, Tze Yuan; Bhat, Rammohan; Lam, Kimberly; Narlawar, Ranjeet S; Cullen, Nicola; Littler, Peter

2010-08-01

Tunneled hemodialysis catheters become essential in dialysis access when there is no possibility of using a functioning arteriovenous fistula. Collateral or occluded veins visible on ultrasound are used for puncture and passage of catheters into the central venous system. Chronically occluded veins are crossed with guidewires to allow dilatation and subsequent passage of hemodialysis catheters. We performed a retrospective analysis of patient demographics, comorbidities, procedural complications, functional survival, performance, and history of previous vascular access. The study group was compared with two control groups in which dialysis catheters were inserted either by radiologists in the interventional suite or by clinicians on the wards. Nineteen patients from the study group were compared with same number of patients in both control groups. The mean age of the study group was higher compared with the control groups. There was no significant difference in mean functional survival, infection rates, dialysis pump speeds in the first 2 weeks, and procedural complications between the study group and the controls. The study group had a significantly higher number of previous vascular access interventions, longer dialysis careers, and more comorbidities. Tunneled dialysis catheter placement by way of collateral or occluded veins appears safe and effective. These techniques give the operator further options when faced with patients possessing challenging vascular access. Indeed, there may be a case for preferential use of these veins to keep patent central veins in reserve.

Matrix and mineral in the sea urchin larval skeleton.

PubMed

Wilt, F H

1999-06-30

The endoskeletal spicules of sea urchin larvae are composed of calcite, a surrounding extracellular matrix, and small amounts of occluded matrix proteins. The spicules are formed by primary mesenchyme cells (PMCs) in the blastocoel of the embryo, where they adopt stereotypical locations, thereby specifying where spicules will form. PMCs also fuse to form cytoplasmic cords connecting the cell bodies, and it is within the cords that spicules arise. The mineral phase contains 5% Mg as well as Ca, and about 0.1% of the mass is protein. The matrix and mineral form concentric plies, and the composite has different physical properties than those of pure calcite. The calcite diffracts as a single crystal and is composed of well-ordered, but not perfectly ordered, microdomains. There is evidence for adsorption of matrix proteins to specific crystal faces at domain boundaries, which may help regulate crystal growth and texture. Immature spicules contain considerable precipitated amorphous CaCO3, and PMCs also have vesicles that contain amorphous CaCO3. This suggests the hypothesis that the cellular precursor to the spicules is actually amorphous CaCO3 stabilized in the cell by protein. The spicule s enveloped by the PMC cord, but is topologically exterior to the cell. The PMC plasmalemma is tightly applied to the developing spicules, except perhaps at the elongating tip. The characteristics, localization, and possible function of the four identified matrix proteins are discussed. SM50, SM37, and PM27 all primarily enclose the mineral, though small amounts are occluded. SM30 is found in cellular vesicles and is probably the principal occluded protein of the spicule.

Comparison of Occlusive and Open Application in a Psoriasis Plaque Test Design, Exemplarily Using Investigations of Mapracorat 0.1% Ointment versus Vehicle and Reference Drugs.

PubMed

Wigger-Alberti, Walter; Williams, Ragna; von Mackensen, Yi-Ling; Hoffman-Wecker, Maciej; Grossmann, Ulrike; Staedtler, Gerald; Nkulikiyinka, Richard; Shakery, Kaweh

2017-01-01

Psoriasis plaque tests (PPTs) are important tools in the early phases of antipsoriatic drug development. Two distinct PPT design variants (open vs. occluded drug application) are commonly used, but no previous work has aimed to directly compare and contrast their performance. We compared the antipsoriatic efficacy of mapracorat 0.1% ointment and reference drugs reported in 2 separate studies, representing open and occluded PPT designs. The drug effect size was measured by sonography (mean change in echo-poor band thickness), chromametry, and standardized clinical assessment. Antipsoriatic effects were detectable for the study drugs in both occluded and open PPTs. Differences between the potency of antipsoriatic drugs and vehicle were observable. The total antipsoriatic effect size appeared to be higher in the occluded PPT than the open PPT, despite the shorter treatment duration (2 vs. 4 weeks). Effect dynamics over time revealed greater differences between some study drugs in the open PPT compared to the occluded PPT. Taking the higher technical challenges for the open PPT into account, we recommend the occluded PPT as a standard screening setting in early drug development. In special cases, considering certain drug aspects or study objectives that would require procedural adaptations, an open PPT could be the better-suited design. Finally, both PPT models show clear advantages: classification as phase I studies, small number of psoriatic subjects, relatively short study duration, excellent discrimination between compounds and concentrations, parallel measurement of treatment response, and go/no go decisions very early in clinical development. © 2017 S. Karger AG, Basel.

Laser scoop desobliteration: a method for minimally invasive remote recanalization of chronically occluded superficial femoral arteries

NASA Astrophysics Data System (ADS)

Heneweer, Carola; Siggelkow, Markus; Helle, Michael; Petzina, Rainer; Wulff, Asmus; Schaefer, Joost P.; Berndt, Rouven; Rusch, Rene; Wedel, Thilo; Klaws, Guenther; Müller-Gerbl, Magdalena; Röcken, Christoph; Jansen, Olav; Lutter, Georg; Cremer, Joachim; Groß, Justus

2015-02-01

Stenosis and occlusion of the superficial femoral artery (SFA) are most common in arterial occlusive disease. There are numerous interventional, surgical, and combined approaches to reconstitute maximum blood supply to the lower limb; however, despite intense clinical research, the long-term success rates are still poor. We present the first results with a catheter prototype for laser-based minimal invasive endarterectomy, called laser scoop desobliteration (LSD). The tip of a glass fiber containing a catheter was modified with a spatula head design and connected to an ultraviolet laser. It was tested in cadavers fixed with the Thiel embalming technique preserving tissue consistency, flexibility, and plasticity. After longitudinal arteriotomy of the SFA, a circular dissection between media and adventitia was performed. Then the LSD catheter was inserted and propagated with a progress of 1 mm/s. Afterward, the atheroma core, which showed a plain surface without substantial attaching tissue debris, was removed. Histological examination of the vessel wall showed that the dissection was performed at the media/adventitia interface. In summary, the constructed LSD catheter allowed a rapid and easy way to perform an endarterectomy, thereby offering an innovative approach in the treatment of chronic occluded SFA.

An experimental-computational analysis of MHV cavitation: effects of leaflet squeezing and rebound.

PubMed

Makhijani, V B; Yang, H Q; Singhal, A K; Hwang, N H

1994-04-01

A combined experimental-computational study was performed to investigate the flow mechanics which could cause cavitation during the squeezing and rebounding phases of valve closure in the 29 mm mitral bileaflet Edwards-Duromedics (ED) mechanical heart valve (MHV). Leaflet closing motion was measured in vitro, and input into a computational fluid mechanics software package, CFD-ACE, to compute flow velocities and pressures in the small gap space between the occluder tip and valve housing. The possibility of cavitation inception was predicted when fluid pressures dropped below the saturated vapor pressure for blood plasma. The computational analysis indicated that cavitation is more likely to be induced during valve rebound rather than the squeezing phase of valve closure in the 29 mm ED-MHV. Also, there is a higher probability of cavitation at lower values of the gap width at the point of impact between the leaflet tip and housing. These predictions of cavitation inception are not likely to be significantly influenced by the water-hammer pressure gradient that develops during valve closure.

AMPLATZER versus Figulla occluder for transcatheter patent foramen ovale closure.

PubMed

Trabattoni, Daniela; Gaspardone, Achille; Sgueglia, Gregory A; Fabbiocchi, Franco; Gioffrè, Gaetano; Montorsi, Piero; Calligaris, Giuseppe; Iamele, Maria; De Santis, Antonella; Bartorelli, Antonio L

2017-04-20

The aim of this observational study was to compare acute and 12-month results of percutaneous closure of patent foramen ovale (PFO) with two occluder devices. Between June 2007 and October 2014, 406 consecutive patients (48.1±13.3 years, 243 women) underwent percutaneous PFO closure with either the AMPLATZER (n=179) or the Figulla (n=227) device after a stroke or a transient ischaemic attack ascribed to the PFO. A right-to-left shunt grade >1 was previously detected in all patients and atrial septal aneurysm was present in 111 (27.5%) patients. Patients were followed up with a contrast transthoracic echocardiogram and clinically at 24 hours, six months, and 12 months after the procedure. A high procedural success was observed in both groups. Despite a trend towards a higher incidence of acute residual shunt immediately after device deployment among Figulla occluder patients, a residual grade ≥2 right-to-left shunt was observed in 4.5% of patients, independently of the device used for PFO closure. The only difference reported after Figulla device implantation was a lower rate of supraventricular arrhythmias (9% vs. 17%, p=0.02). According to this two-centre study, PFO closure appears safe and effective with the Figulla occluder as well as with the AMPLATZER device.

75 FR 26889 - Airworthiness Directives; Arrow Falcon Exporters, Inc. (previously Utah State University) et al...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-13

... the forward tip weight retention block (tip block) or aft tip closure (tip closure), loss of the blade...) forward tip weight retention block (tip block) and the aft tip closure (tip closure) for adhesive bond... prevent loss of a tip block or tip closure, loss of a blade, and subsequent loss of control of the...

Transcutaneous closure of chronic broncho-pleuro-cutaneous fistula by duct occluder device

PubMed Central

Marwah, Vikas; Ravikumar, R; Rajput, Ashok Kumar; Singh, Amandeep

2016-01-01

Bronchopleural fistula (BPF) is a well known complication of several pulmonary conditions posing challenging management problem and is often associated with high morbidity and mortality. Though no consensus exists on a definite closure management algorithm, strategies for closure widely include various methods like tube thoracostomy with suction, open surgical closure, bronchoscopy directed glue, coiling and sealants which now also includes use of occlusion devices. We report a case in which a novel method of delivery and closure of recurrent post-operative broncho-pleuro-cutaneous fistula by a duct occluder device was done transcutaneously which has not been previously described in literature. PMID:27051115

Dense Accumulation of Lipiodol Emulsion in Hepatocellular Carcinoma Nodule during Selective Balloon-occluded Transarterial Chemoembolization: Measurement of Balloon-occluded Arterial Stump Pressure

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

Irie, Toshiyuki, E-mail: toshiyuki.irie.rq@hitachi.com; Kuramochi, Masashi, E-mail: masashi.kuramochi.sh@hitachi.com; Takahashi, Nobuyuki, E-mail: nbyktakahashiodn@yahoo.co.jp

2013-06-15

Purpose. To reveal the mechanism of dense accumulation of lipiodol emulsion (LE) in hepatocellular carcinoma (HCC) during selective balloon-occluded transarterial chemoembolization (B-TACE). Methods. Balloon-occluded arterial stump pressure (BOASP) at the embolization portion was measured during selective B-TACE for 43 nodules in 42 patients. Fluoroscopy and digital subtraction angiography were prospectively observed during selective B-TACE to note whether dense LE accumulation in HCC occurred. The LE concentration ratio of HCC to embolized liver parenchyma (LECHL ratio) was also calculated for each treatment on the basis of the computed tomographic scan obtained immediately after selective B-TACE. The relationships between degree of LEmore » accumulation and the BOASP, as well as the LECHL ratio, were analyzed. Results. Arterial flow beyond the catheter tip was maintained even after balloon inflation. In 39 of 43 treatments, LE inflow into the nontumorous liver parenchyma ceased immediately after LE droplets were filled in arteries of the nontumorous liver parenchyma while LE inflow into the HCC nodule continued (group 1). More dense LE accumulation in HCC nodule was obtained in these 39 treatments. In four treatments, LE inflow both into the nontumorous liver parenchyma and into the HCC nodule continued, and no dense LE accumulation in HCC nodule was observed (group 2). In these four treatments, thick anastomotic vessels with collateral artery were noted. The BOASP in group 1 was (mean {+-} SD) 33.8 {+-} 12.8 mmHg (range 13-64 mmHg) and that in group 2 was 92.3 {+-} 7.4 mmHg (range 83-100 mmHg). There was a statistically significant difference in BOASP between groups (p = 0.00004, Welch's t test). The LECHL ratio in group 1 was 18.3 {+-} 13.9 (range 2.9-54.2) and that in group 2 was 2.6 {+-} 1.1 (range 1.7-4.2). There was a statistically significant difference in the LECHL ratio between the groups (p = 0.000034, Welch's t test). Conclusion. Selective B-TACE induced dense LE accumulation in HCC nodules in 39 (91 %) of 43 treatments in which BOASP was 64 mmHg or less.« less

Balloon-occluded Retrograde Transvenous Obliteration (BRTO): Preprocedural Evaluation and Imaging

PubMed Central

Al-Osaimi, Abdullah M. S.; Sabri, Saher S.; Caldwell, Stephen H.

2011-01-01

Patients undergoing balloon retrograde transvenous obliteration (BRTO) are mostly decompensated cirrhotic with either bleeding gastric varices (GV) or hepatic encephalopathy. It is crucial that clinicians are up-to-date with the assessments needed prior to BRTO to anticipate and prevent complications, and to deliver critical quality care. These patients will require preprocedural assessments and management, including endoscopic, clinical, laboratory, and imaging evaluation. Endoscopic evaluation is mandatory prior to BRTO, and it is highly recommended that it be performed at the same institution where BRTO will be performed. It is essential that clinicians are aware of the potential benefits and complications that may result from BRTO. These complications should be anticipated and prevented when possible. For GV bleeders, there should be consideration of a transvenous intrahepatic portosystemic shunt (TIPS) during or before BRTO in patients with refractory ascites or pleural effusion, as well as endoscopic banding or a TIPS in patients with high-risk esophageal varices. Patients undergoing BRTO are usually complicated and require a team approach. In this article, the authors address these assessment and preparatory management and planning procedures prior to the BRTO procedure as well as expected outcomes and potential complications. PMID:22942546

Aspirex Thrombectomy in Occluded Dialysis Access: A Retrospective Study

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

Dyer, Jules, E-mail: Jules.Dyer@nhs.net; Rosa, Joao; Chachlani, Menka

PurposeThis study is the first to present the outcomes of the Straub Aspirex device for the salvage of occluded renal dialysis access fistulae.Materials and MethodsThis is a retrospective study, using data from the Renal Unit and Radiology Department database. It included all the patients between 2010 and 2014 who underwent percutaneous mechanical thrombectomy (PMT) treated by JD. Aspirex is an over-the-wire, 6–10 French catheter within which is a rapidly rotating helix which draws thrombus into a window near the tip which it then macerates and removes. Access survival was assessed using the Kaplan–Meier method, and multi-variant analysis was performed usingmore » the Cox proportional hazards model. Significance was considered if p < 0.05.ResultsA total of 27 procedures were performed for 19 patients. 13 had autologous arterio-venous fistulae, and 14 had synthetic (PTFE) arterio-venous grafts. 15 were males, 4 females. 100 % of the patients successfully had a channel of thrombus removed. This resulted in an 81.5 % initial clinical success, with primary patency rates of 53.6, 44.3 and 33 % by days 30, 90 and 480, respectively, without significant difference of any analysed covariates. No major complication (pulmonary embolus, paradoxical cerebral infarction, limb ischaemia or significant haemorrhage) occurred.ConclusionAspirex has rates of patency and complication similar to other PMT devices. No covariant studied affected outcome.« less

Fifty-three years' experience with randomized clinical trials of emergency portacaval shunt for bleeding esophageal varices in Cirrhosis: 1958-2011.

PubMed

Orloff, Marshall J

2014-02-01

Emergency treatment of bleeding esophageal varices (BEV) consists mainly of endoscopic and pharmacologic measures, with transjugular intrahepatic portal-systemic shunt (TIPS) performed when bleeding is not controlled. Surgical shunt has been relegated to salvage. At the University of California, San Diego, Medical Center, our group has conducted 10 studies of emergency portacaval shunt (EPCS) during 46 years. To describe 2 randomized clinical trials (RCTs) conducted from 1988 to 2011 in unselected consecutive patients who received emergency treatment for BEV. In RCT No. 1, a total of 211 unselected consecutive patients with cirrhosis and acute BEV were randomized to emergency endoscopic sclerotherapy (EEST) (n=106) or EPCS (n=105). In RCT No. 2, a total of 154 unselected consecutive patients with cirrhosis and acute BEV were randomized to TIPS (n=78) or EPCS (n=76). Diagnostic workup was completed within 6 hours of initial contact, and primary treatment was initiated within 8 to 12 hours. Regular follow-up for up to 10 years was accomplished in 100% of the patients. In RCT No. 1, EEST or EPCS; in RCT No. 2, TIPS or EPCS. The 2 groups were compared with regard to survival, control of bleeding, portal-systemic encephalopathy, and direct cost of care. RESULTS Distribution in Child risk classes was almost identical. One-third of patients were in Child class C. Permanent control of bleeding was achieved by EEST in only 20% of the patients and by TIPS in only 22%. In contrast, EPCS permanently controlled bleeding in 97% and 100% of the patients in RCT No. 2 and RCT No. 1, respectively (P<.001). Survival was significantly greater following EPCS than after EEST and TIPS (P<.001). Median survival was more than 10 years following EPCS compared with 1.99 years after TIPS. Occlusion of TIPS was demonstrated in 84% of the patients, 63% of whom underwent TIPS revision, which failed in 80% of the cases. Recurrent portal-systemic encephalopathy developed in 35% of the patients who underwent EEST and 61% of those who received TIPS. In contrast, portal-systemic encephalopathy occurred in 15% of the patients who received EPCS in RCT No. 1 and 21% of those in RCT No. 2. Direct costs of care were 5 to 7 times greater in the EEST ($168100) and TIPS ($264800) groups than in the EPCS ($39000) group (P<.001). Emergency portacaval shunt permanently stopped variceal bleeding, almost never became occluded, accomplished 5 times the long-term survival than EEST or TIPS, and was much less costly than EEST or TIPS. The widespread practice of using EPCS mainly as salvage for failure of endoscopic therapy or TIPS is not supported by the definitive results of these long-term RCTs in unselected patients with cirrhosis. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00690027 and NCT00734227.

Detection scheme for a partially occluded pedestrian based on occluded depth in lidar-radar sensor fusion

NASA Astrophysics Data System (ADS)

Kwon, Seong Kyung; Hyun, Eugin; Lee, Jin-Hee; Lee, Jonghun; Son, Sang Hyuk

2017-11-01

Object detections are critical technologies for the safety of pedestrians and drivers in autonomous vehicles. Above all, occluded pedestrian detection is still a challenging topic. We propose a new detection scheme for occluded pedestrian detection by means of lidar-radar sensor fusion. In the proposed method, the lidar and radar regions of interest (RoIs) have been selected based on the respective sensor measurement. Occluded depth is a new means to determine whether an occluded target exists or not. The occluded depth is a region projected out by expanding the longitudinal distance with maintaining the angle formed by the outermost two end points of the lidar RoI. The occlusion RoI is the overlapped region made by superimposing the radar RoI and the occluded depth. The object within the occlusion RoI is detected by the radar measurement information and the occluded object is estimated as a pedestrian based on human Doppler distribution. Additionally, various experiments are performed in detecting a partially occluded pedestrian in outdoor as well as indoor environments. According to experimental results, the proposed sensor fusion scheme has much better detection performance compared to the case without our proposed method.

Management of a large atrial septal occluder embolized to the left ventricular outflow tract without the use of cardiac surgery.

PubMed

Loh, Joshua P; Satler, Lowell F; Slack, Michael C

2014-09-01

Transcatheter closure of secundum-type atrial septal defects (ASDs) using the AMPLATZER™ Septal Occluder (ASO) has been in use for more than a decade since its US Food and Drug Administration approval in 2001. Device embolization remains an uncommon complication, which can sometimes occur after the initial deployment. Previous reports of ASO devices embolized to the left ventricle have primarily been managed by open-heart surgical retrieval. We present a case of an ASO device embolized to the left ventricular outflow tract (LVOT) 18 hr after initial implantation, which was successfully retrieved percutaneously, followed by successful closure of the ASD using a larger device. © 2014 Wiley Periodicals, Inc.

Recent development of transcatheter closure of atrial septal defect and patent foramen ovale with occluders.

PubMed

Tang, Baiyu; Su, Feng; Sun, Xiangke; Wu, Qin; Xing, Quansheng; Li, Suming

2018-01-01

Atrial septal defect (ASD) and patent foramen ovale (PFO) are common clinical congenital heart defects. As an effective method for the treatment of ASD and PFO, transcatheter closure with occluders presents many advantages, including safety, ease of operation, minimal invasiveness, and reduced complications. This contribution reviews the various types of occluders currently used in clinical applications and under development, including non degradable occluders, partially degradable occluders, and totally degradable occluders. A number of case studies are described in detail. Comparison is made on the treatment outcomes using different occulders. Future development of transcatheter closure is discussed, in particular the use of totally degradable occluders. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 433-443, 2018. © 2016 Wiley Periodicals, Inc.

Motor Execution Affects Action Prediction

ERIC Educational Resources Information Center

Springer, Anne; Brandstadter, Simone; Liepelt, Roman; Birngruber, Teresa; Giese, Martin; Mechsner, Franz; Prinz, Wolfgang

2011-01-01

Previous studies provided evidence of the claim that the prediction of occluded action involves real-time simulation. We report two experiments that aimed to study how real-time simulation is affected by simultaneous action execution under conditions of full, partial or no overlap between observed and executed actions. This overlap was analysed by…

Amodal Completion in Bonobos

ERIC Educational Resources Information Center

Nagasaka, Yasuo; Brooks, Daniel I.; Wasserman, Edward A.

2010-01-01

We trained two bonobos to discriminate among occluded, complete, and incomplete stimuli. The occluded stimulus comprised a pair of colored shapes, one of which appeared to occlude the other. The complete and incomplete stimuli involved the single shape that appeared to have been partially covered in the occluded stimulus; the complete stimulus…

An in vivo assessment of the effects of using different implant abutment occluding materials on implant microleakage and the peri-implant microbiome

NASA Astrophysics Data System (ADS)

Rubino, Caroline

Microleakage may be a factor in the progression of peri-implant pathology. Microleakage in implant dentistry refers to the passage of bacteria, fluids, molecules or ions between the abutment-implant interface to and from the surrounding periodontal tissues. This creates a zone of inflammation and reservoir of bacteria at the implant-abutment interface. Bone loss typically occurs within the first year of abutment connection and then stabilizes. It has not yet been definitively proven that the occurrence of microleakage cannot contribute to future bone loss or impede the treatment of peri-implant disease. Therefore, strategies to reduce or eliminate microleakage are sought out. Recent evidence demonstrates that the type of implant abutment channel occluding material can affect the amount of microleakage in an in vitro study environment. Thus, we hypothesize that different abutment screw channel occluding materials will affect the amount of observed microleakage, vis-a-vis the correlation between the microflora found on the abutment screw channel occluding material those found in the peri-implant sulcus. Additional objectives include confirming the presence of microleakage in vivo and assessing any impact that different abutment screw channel occluding materials may have on the peri-implant microbiome. Finally, the present study provides an opportunity to further characterize the peri-implant microbiome. Eight fully edentulous patients restored with at dental implants supporting screw-retained fixed hybrid prostheses were included in the study. At the initial appointment (T1), the prostheses were removed and the implants and prostheses were cleaned. The prostheses were then inserted with polytetrafluoroethylene tape (PTFE, TeflonRTM), cotton, polyvinyl siloxane (PVS), or synthetic foam as the implant abutment channel occluding material and sealed over with composite resin. About six months later (T2), the prostheses were removed and the materials collected. Paper points were used to sample the peri-implant sulcus bacteria. All samples were then submitted to DNA purification, polymerase chain reaction (PCR), and sequencing protocols to assess relative numbers of bacterial species. Periodontal parameters were collected at both time points. Overall, our findings support several conclusions. Different implant abutment channel occluding materials appear to have no effect on the amount of observed microleakage and the peri-implant microbiome. Evidence for microleakage was found in the present study, corroborating existing in vivo evidence. Finally, we gained several insights regarding the peri implant microbiome. Of note, the peri-implant microbiome is well described by the classical periodontal microbial complexes, but a large portion consists of bacteria not previously classified into the microbial complexes.

Phonation Threshold Pressure Measurement With a Semi-Occluded Vocal Tract

PubMed Central

Titze, Ingo R.

2015-01-01

Purpose The purpose of this article was to determine if a semi-occluded vocal tract could be used to measure phonation threshold pressure. This is in contrast to the shutter technique, where an alternation between a fully occluded tract and an unoccluded tract is used. Method Five male and 5 female volunteers phonated through a thin straw held between the lips. Oral pressure behind the lips was measured. Mathematical predictions of phonation threshold pressures were compared to the measured ones over a range of frequencies. Results It was shown that, for a 2.5-mm diameter straw, phonation threshold pressures were obtainable over a 2-octave range of fundamental frequency by all volunteers. In magnitude, the pressures agreed with the 0.2–0.5 kPa values obtained in previous investigations. Sensitivity to viscoelastic and geometric properties of the vocal folds was generally not compromised with greater oral impedance, but some differences were predicted theoretically in contrast to an open mouth configuration. Conclusion Because phonation threshold pressure is always dependent on vocal tract interaction, it may be advantageous to choose an exact and fixed oral semi-occlusion for the measurement and interpret the results in light of the known acoustic load. PMID:19641082

Subintimal Recanalization of Occluded Stents: The Substent Technique

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

Diamantopoulos, Athanasios, E-mail: adiamant@upatras.gr; Katsanos, Konstantinos; Spiliopoulos, Stavros

2013-08-01

PurposeApplication of metal stents is complicated by neointimal hyperplasia leading to vessel restenosis and reocclusion. Treatment options in cases presenting with complete occlusion of the stented segment and recurrent critical limb ischemia (CLI) are limited. We present the option of the subintimal/substent technique in dealing with occluded stents.MethodsThe study included patients presenting with recurrent CLI due to impaired blood flow as a result of complete occlusion of previously inserted metal stents and unsuccessful intraluminal crossing of the lesion via either the antegrade or retrograde approach. In these cases, crossing the occlusion through the subintimal/substent plane was attempted. Primary end pointsmore » included technical success, safety of the procedure, clinical improvement, and limb salvage, while secondary end points were patient survival, primary patency, and vessel restenosis rates at 1-year follow-up. Study end points were calculated by Kaplan-Meier survival analysis.ResultsBetween July 2006 and October 2011, a total of 14 patients (mean age 69.14 {+-} 12.59 years, 12 men) were treated with the substent technique and included in the analysis. Technical success rate was 85.71 % (12 of 14), with a total lesion length of 193.57 {+-} 90.78 mm. The mean occluded stented segment length was 90.21 {+-} 44.34 mm. In 10 (83.33 %) of 12 cases, a new stent had to be placed by the side of the old occluded one, while the remaining two cases (16.67 %) were treated only with balloon angioplasty. No serious adverse events were noted during the immediate postprocedural period. All successfully treated patients improved clinically. Estimated limb salvage was 90.9 %, and patient survival rate was 90.0 % at 1 year's follow-up. Primary patency was 45.50 % and vessel restenosis 77.30 %.ConclusionSubintimal recanalization of occluded metal stents through the substent plane is a valuable alternative treatment option, especially in patients with recurrent CLI with few alternatives.« less

Oscillatory Activity in the Infant Brain and the Representation of Small Numbers

PubMed Central

Leung, Sumie; Mareschal, Denis; Rowsell, Renee; Simpson, David; Iaria, Leon; Grbic, Amanda; Kaufman, Jordy

2016-01-01

Gamma-band oscillatory activity (GBA) is an established neural signature of sustained occluded object representation in infants and adults. However, it is not yet known whether the magnitude of GBA in the infant brain reflects the quantity of occluded items held in memory. To examine this, we compared GBA of 6–8 month-old infants during occlusion periods after the representation of two objects vs. that of one object. We found that maintaining a representation of two objects during occlusion resulted in significantly greater GBA relative to maintaining a single object. Further, this enhancement was located in the right occipital region, which is consistent with previous object representation research in adults and infants. We conclude that enhanced GBA reflects neural processes underlying infants’ representation of small numbers. PMID:26903821

Oscillatory Activity in the Infant Brain and the Representation of Small Numbers.

PubMed

Leung, Sumie; Mareschal, Denis; Rowsell, Renee; Simpson, David; Iaria, Leon; Grbic, Amanda; Kaufman, Jordy

2016-01-01

Gamma-band oscillatory activity (GBA) is an established neural signature of sustained occluded object representation in infants and adults. However, it is not yet known whether the magnitude of GBA in the infant brain reflects the quantity of occluded items held in memory. To examine this, we compared GBA of 6-8 month-old infants during occlusion periods after the representation of two objects vs. that of one object. We found that maintaining a representation of two objects during occlusion resulted in significantly greater GBA relative to maintaining a single object. Further, this enhancement was located in the right occipital region, which is consistent with previous object representation research in adults and infants. We conclude that enhanced GBA reflects neural processes underlying infants' representation of small numbers.

Determining biological tissue optical properties via integrating sphere spatial measurements

DOEpatents

Baba, Justin S [Knoxville, TN; Letzen, Brian S [Coral Springs, FL

2011-01-11

An optical sample is mounted on a spatial-acquisition apparatus that is placed in or on an enclosure. An incident beam is irradiated on a surface of the sample and the specular reflection is allowed to escape from the enclosure through an opening. The spatial-acquisition apparatus is provided with a light-occluding slider that moves in front of the sample to block portions of diffuse scattering from the sample. As the light-occluding slider moves across the front of the sample, diffuse light scattered into the area of the backside of the light-occluding slider is absorbed by back side surface of the light-occluding slider. By measuring a baseline diffuse reflectance without a light-occluding slider and subtracting measured diffuse reflectance with a light-occluding slider therefrom, diffuse reflectance for the area blocked by the light-occluding slider can be calculated.

Evaluation of blotchy pigments in the anterior chamber angle as a sign of angle closure

PubMed Central

Rao, Harsha L; Mungale, Sachin C; Kumbar, Tukaram; Parikh, Rajul S; Garudadri, Chandra S

2012-01-01

Background: Blotchy pigments in the anterior chamber (AC) angle are considered diagnostic of primary angle closure (PAC). But there are no reports either on the prevalence of blotchy pigments in AC angles or the validity of this sign. Aims: To determine the prevalence of blotchy pigments in AC angles and to evaluate their relationship with glaucomatous optic neuropathy (GON) in eyes with occludable angles. Setting and Design: Cross-sectional, comparative study. Materials and Methods: Gonioscopy was performed in 1001 eyes of 526 subjects (245 eyes of 148 consecutive, occludable angle subjects and 756 eyes of 378 non-consecutive, open angle subjects), above 35 years of age. Quadrant-wise location of blotchy pigments was documented. Statistical Analysis: Odds of blotchy pigments in occludable angles against that in open angles were evaluated. Relationship of GON with blotchy pigments in occludable angle eyes was evaluated using a multivariate model. Results: Prevalence of blotchy pigments in occludable angles was 28.6% (95% CI, 22.9-34.3) and in open angles was 4.7% (95% CI, 3.2-6.3). Blotchy pigments were more frequently seen in inferior (16%) and superior quadrants (15%) of occludable angles, and inferior quadrant of open angles (4%). Odds of superior quadrant blotchy pigments in occludable angles were 33 times that in open angles. GON was seen in 107 occludable angle eyes. Blotchy pigments were not significantly associated with GON (odds ratio = 0.5; P = 0.1). Conclusions: Blotchy pigments were seen in 28.6% of occludable angle eyes and 4.7% of open angles eyes. Presence of blotchy pigments in the superior quadrant is more common in occludable angles. Presence of GON in occludable angle eyes was not associated with blotchy pigments. PMID:23202393

Safety and efficacy of Cardi-O-fix occluder for percutaneous closure of a patent foramen ovale

PubMed Central

Zhao, Enfa; Liu, Wenjuan; Zhang, Yushun; Cheng, Gesheng; Du, Yajuan; He, Lu; Wang, Xingye; He, Xumei

2017-01-01

Abstract Background: Amplatzer occluder and Cardio-O-fix occluder are currently used in percutaneous closure of patent foramen ovale. However, there is still a lack of relevant reports comparison the differences between them. The aim of this study was to evaluate the short-term and mid-term safety and efficacy of the Cardi-O-fix occluder in preventing recurrent cerebrovascular events in patients with a patent foramen ovale (PFO). Methods: We enrolled 246 patients (105 men) with a PFO from May 30, 2013 to March 30, 2015 in this single-center prospective study. All patients were treated by PFO interventional closure, with the Cardi-O-fix PFO occluder being used in 180 patients and the Amplatzer PFO occluder being utilized in the remaining 66 patients. After the procedure, we verified the safety and efficacy of different devices using contrast transthoracic echocardiography. Results: Neither recurrent stroke nor death was encountered during the follow-up of 12 months. Transient ischemic attack (TIA) was noted in 2 patients (1.1%) in the Cardi-O-fix PFO occluder group, and 1 patient suffered from TIA (1.5%) in the Amplatzer PFO occluder group. Among them, only 1 patient exhibited a small right to left shunt (RLS). There was no statistical difference in recurrent cerebral ischemic events. Three cases of paroxysmal atrial fibrillation were observed in the Cardi-O-fix PFO occluder group. One reverted spontaneously to sinus rhythm and the other 2 cases had pharmacologic conversion to sinus rhythm. One case of paroxysmal atrial fibrillation occurred in the Amplatzer group, which underwent pharmacologic conversion to sinus rhythm. There was no significant difference between the 2 groups regarding incidence of arrhythmia. No occluder translocation, erosion, pericardial effusion, and puncture site bleeding were observed in the 2 groups within 12 months of follow-up. The complete closure rates of the Cardi-O-fix and Amplatzer PFO occluder devices at the 12 months after the procedure were 73.9% and 63.6%, respectively, and the effective closure rates were 90.6% and 86.4%, respectively. There was no statistically significant difference in the complete closure rate and effective occlusion rate (P > 0.05) between the devices. Conclusions: There was no significant difference in the short- and mid-term efficacy and safety between the Cardi-O-fix PFO occluder and Amplatzer PFO occluder. The efficacy and safety of the Cardi-O-fix occluder were comparable to those of the Amplatzer PFO occluder. PMID:28383438

Improved Temperature Dynamic Model of Turbine Subcomponents for Facilitation of Generalized Tip Clearance Control

NASA Technical Reports Server (NTRS)

Kypuros, Javier A.; Colson, Rodrigo; Munoz, Afredo

2004-01-01

This paper describes efforts conducted to improve dynamic temperature estimations of a turbine tip clearance system to facilitate design of a generalized tip clearance controller. This work builds upon research previously conducted and presented in and focuses primarily on improving dynamic temperature estimations of the primary components affecting tip clearance (i.e. the rotor, blades, and casing/shroud). The temperature profiles estimated by the previous model iteration, specifically for the rotor and blades, were found to be inaccurate and, more importantly, insufficient to facilitate controller design. Some assumptions made to facilitate the previous results were not valid, and thus improvements are presented here to better match the physical reality. As will be shown, the improved temperature sub- models, match a commercially validated model and are sufficiently simplified to aid in controller design.

Transcatheter closure of ventricular septal defect with Occlutech Duct Occluder.

PubMed

Atik-Ugan, Sezen; Saltik, Irfan Levent

2018-04-01

Patent ductus arteriosus occluders are used for transcatheter closure of ventricular septal defects, as well as for closure of patent ductus arteriosus. The Occlutech Duct Occluder is a newly introduced device for transcatheter closure of patent ductus arteriosus. Here, we present a case in which the Occlutech Duct Occluder was successfully used on a patient for the closure of a perimembraneous ventricular septal defect.

Delayed Infective Endocarditis with Mycotic Aneurysm Rupture below the Mechanical Valved Conduit after the Bentall Procedure.

PubMed

Chen, Mei-Ling; Chen, Michael Y; Yin, Wei-Hsian; Wei, Jeng; Wang, Ji-Hung

2014-07-01

The Bentall procedure is the gold standard for treating aortic dissection complicated with valvular and ascending aorta disease. Recent results for this procedure have been excellent; nearly 100% of patients remain free of infective endocarditis in long-term follow-up. We report a case of delayed Streptococcus agalactiae infective endocarditis complicated by mycotic aneurysm in a man who had undergone the Bentall procedure with a mechanical valve conduit 15 years previously. The mycotic aneurysm was located in the remnant aortic root, below the mechanical valve conduit, and later ruptured into the right atrium. The patient was treated conservatively and survived the acute period. Later, the aortic root defect was repaired successfully by means of a hybrid technique using a Amplatzer duct occluder. Amplatzer duct occluder; Aortic dissection; Bentall technique; Infective endocarditis; Mycotic aneurysm.

Decoding information about dynamically occluded objects in visual cortex

PubMed Central

Erlikhman, Gennady; Caplovitz, Gideon P.

2016-01-01

During dynamic occlusion, an object passes behind an occluding surface and then later reappears. Even when completely occluded from view, such objects are experienced as continuing to exist or persist behind the occluder, even though they are no longer visible. The contents and neural basis of this persistent representation remain poorly understood. Questions remain as to whether there is information maintained about the object itself (i.e. its shape or identity) or, non-object-specific information such as its position or velocity as it is tracked behind an occluder as well as which areas of visual cortex represent such information. Recent studies have found that early visual cortex is activated by “invisible” objects during visual imagery and by unstimulated regions along the path of apparent motion, suggesting that some properties of dynamically occluded objects may also be neurally represented in early visual cortex. We applied functional magnetic resonance imaging in human subjects to examine the representation of information within visual cortex during dynamic occlusion. For gradually occluded, but not for instantly disappearing objects, there was an increase in activity in early visual cortex (V1, V2, and V3). This activity was spatially-specific, corresponding to the occluded location in the visual field. However, the activity did not encode enough information about object identity to discriminate between different kinds of occluded objects (circles vs. stars) using MVPA. In contrast, object identity could be decoded in spatially-specific subregions of higher-order, topographically organized areas such as ventral, lateral, and temporal occipital areas (VO, LO, and TO) as well as the functionally defined LOC and hMT+. These results suggest that early visual cortex may represent the dynamically occluded object’s position or motion path, while later visual areas represent object-specific information. PMID:27663987

Comparison of factors associated with occludable angle between american Caucasians and ethnic Chinese.

PubMed

Wang, Ye Elaine; Li, Yingjie; Wang, Dandan; He, Mingguang; Lin, Shan

2013-11-21

To determine if factors associated with gonioscopy-determined occludable angle among American Caucasians are similar to those found in ethnic Chinese. This is a prospective cross-sectional study with 120 American Caucasian, 116 American Chinese, and 116 mainland Chinese subjects. All three groups were matched for sex and age (40-80 years). Gonioscopy was performed for each subject (occludable angles = posterior trabecular meshwork not visible for ≥2 quadrants). Anterior segment optical coherence tomography and customized software was used to measure anterior segment biometry and iris parameters, including anterior chamber depth/width (ACD, ACW), lens vault (LV), and iris thickness/area/curvature. In both Chinese and Caucasians, eyes with occludable angles had smaller ACD and ACW, and larger LV and iris curvature than eyes with open angles (all P < 0.005). Chinese eyes had smaller ACD and ACW than Caucasian eyes (both P < 0.01) in the occludable angle cohort. Iris characteristics did not differ significantly between Chinese and Caucasians in the occludable angle cohort. Based on multivariate logistic regression, gonioscopy-determined occludable angle was significantly associated with LV, iris area, and sex (all P < 0.03) in Chinese; and with LV, ACD, iris thickness, age, and sex (all P < 0.04) in Caucasians. Several factors associated with occludable angle differed between Caucasians and Chinese, suggesting potentially different mechanisms in occludable angle development in the two racial groups. This is the first study to demonstrate that lens vault is an important anterior segment optical coherence tomography parameter in the screening for angle closure in Caucasians. In addition, iris thickness was a significant predictor for occludable angles in Caucasians but was not in ethnic Chinese.

Comparison of Factors Associated With Occludable Angle Between American Caucasians and Ethnic Chinese

PubMed Central

Wang, Ye Elaine; Li, Yingjie; Wang, Dandan; He, Mingguang; Lin, Shan

2013-01-01

Purpose. To determine if factors associated with gonioscopy-determined occludable angle among American Caucasians are similar to those found in ethnic Chinese. Methods. This is a prospective cross-sectional study with 120 American Caucasian, 116 American Chinese, and 116 mainland Chinese subjects. All three groups were matched for sex and age (40–80 years). Gonioscopy was performed for each subject (occludable angles = posterior trabecular meshwork not visible for ≥2 quadrants). Anterior segment optical coherence tomography and customized software was used to measure anterior segment biometry and iris parameters, including anterior chamber depth/width (ACD, ACW), lens vault (LV), and iris thickness/area/curvature. Results. In both Chinese and Caucasians, eyes with occludable angles had smaller ACD and ACW, and larger LV and iris curvature than eyes with open angles (all P < 0.005). Chinese eyes had smaller ACD and ACW than Caucasian eyes (both P < 0.01) in the occludable angle cohort. Iris characteristics did not differ significantly between Chinese and Caucasians in the occludable angle cohort. Based on multivariate logistic regression, gonioscopy-determined occludable angle was significantly associated with LV, iris area, and sex (all P < 0.03) in Chinese; and with LV, ACD, iris thickness, age, and sex (all P < 0.04) in Caucasians. Conclusions. Several factors associated with occludable angle differed between Caucasians and Chinese, suggesting potentially different mechanisms in occludable angle development in the two racial groups. This is the first study to demonstrate that lens vault is an important anterior segment optical coherence tomography parameter in the screening for angle closure in Caucasians. In addition, iris thickness was a significant predictor for occludable angles in Caucasians but was not in ethnic Chinese. PMID:24168992

ACTIVE DELIVERY CABLE TUNED TO DEVICE DEPLOYMENT STATE: ENHANCED VISIBILITY OF NITINOL OCCLUDERS DURING PRE-CLINICAL INTERVENTIONAL MRI

PubMed Central

Bell, Jamie A.; Saikus, Christina E.; Ratnayaka, Kanishka; Barbash, Israel M.; Faranesh, Anthony Z.; Franson, Dominique N.; Sonmez, Merdim; Slack, Michael C.; Lederman, Robert J.; Kocaturk, Ozgur

2012-01-01

Purpose To develop an active delivery system that enhances visualization of nitinol cardiac occluder devices during deployment under real-time MRI. Materials and Methods We constructed an active delivery cable incorporating a loopless antenna and a custom titanium microscrew to secure the occluder devices. The delivery cable was tuned and matched to 50Ω at 64 MHz with the occluder device attached. We used real-time balanced SSFP in a wide-bore 1.5T scanner. Device-related images were reconstructed separately and combined with surface-coil images. The delivery cable was tested in vitro in a phantom and in vivo in swine using a variety of nitinol cardiac occluder devices. Results In vitro, the active delivery cable provided little signal when the occluder device was detached and maximal signal with the device attached. In vivo, signal from the active delivery cable enabled clear visualization of occluder device during positioning and deployment. Device release resulted in decreased signal from the active cable. Post-mortem examination confirmed proper device placement. Conclusions The active delivery cable enhanced the MRI depiction of nitinol cardiac occluder devices during positioning and deployment, both in conventional and novel applications. We expect enhanced visibility to contribute to effectiveness and safety of new and emerging MRI-guided treatments. PMID:22707441

Cortical dynamics of three-dimensional figure-ground perception of two-dimensional pictures.

PubMed

Grossberg, S

1997-07-01

This article develops the FACADE theory of 3-dimensional (3-D) vision and figure-ground separation to explain data concerning how 2-dimensional pictures give rise to 3-D percepts of occluding and occluded objects. The model describes how geometrical and contrastive properties of a picture can either cooperate or compete when forming the boundaries and surface representation that subserve conscious percepts. Spatially long-range cooperation and spatially short-range competition work together to separate the boundaries of occluding figures from their occluded neighbors. This boundary ownership process is sensitive to image T junctions at which occluded figures contact occluding figures. These boundaries control the filling-in of color within multiple depth-sensitive surface representations. Feedback between surface and boundary representations strengthens consistent boundaries while inhibiting inconsistent ones. Both the boundary and the surface representations of occluded objects may be amodally completed, while the surface representations of unoccluded objects become visible through modal completion. Functional roles for conscious modal and amodal representations in object recognition, spatial attention, and reaching behaviors are discussed. Model interactions are interpreted in terms of visual, temporal, and parietal cortices.

Application of Cardio-O-Fix occluders for transcatheter closure of patent ductus arteriosus and interatrial communications: Preliminary experience.

PubMed

Białkowski, Jacek; Szkutnik, Małgorzata; Fiszer, Roland; Głowacki, Jan; Banaszak, Paweł; Zembala, Marian

2010-01-01

Transcatheter treatment has become the method of choice for treating many heart defects. Recently, Cardio-O-Fix occluder (COF) - a new, self-expandable nitinol wire-mesh device very similar to the Amplatzer device - has been introduced into clinical practice. To the best of our knowledge, this is the first publication related to its application. Five patients aged from six months to 69 years were included in the study: two with atrial septal defect (ASD), one with patent foramen ovale (PFO) after cryptogenic stroke, and two with patent ductus arteriosus (PDA). These latter two comprised one six month old infant with co-existent hypertrophied cardiomyopathy, and a 53 year-old woman with recanalized PDA after previous ligation. All were treated percutaneously with COF. There was no preliminary patient selection. The only limitation was the size of the devices in our possession (16 and 22 mm ASD COF, 25 PFO COF, 4/6 and 6/8 PDA COF). The implantation technique was the same as previously described for Amplatzer occluders. All procedures were finished successfully with complete closure of the shunt. No complications were observed during a six month follow-up. In the child with PDA, we observed decrease of gradient from 80 to 60 mm Hg in hypertrophied left ventricular outflow tract, although a small protrusion of PDA-COF device was noted in the descending aorta (8 mm Hg gradient in ECHO). In the patient with recanalized PDA, the procedure was performed after arterio-venous loop creation. Mean fluoroscopy time was 4.4 (range from 1.6 to 11) minutes. Our preliminary experience indicates that the application of Cardio-O-Fix devices is safe and effective.

What Do Dogs know about Hidden Objects?

PubMed Central

Miller, Holly C.; Rayburn-Reeves, Rebecca; Zentall, Thomas R.

2009-01-01

Previous research has found that dogs will search accurately for an invisibly displaced object when the task is simplified and contextual ambiguity is eliminated (Doré et. al., 1996; Miller et. al., 2008). For example, when an object is placed inside of one of two identical occluders attached to either end of a rotating beam and that beam is rotated 90°, dogs search inside of the appropriate occluder. The current research confirmed this finding and tested the possibility that the dogs were using a perceptual/conditioning mechanism (i.e., their gaze was drawn to the occluder as the object was placed inside and they continued looking at it as it rotated). The test was done by introducing a delay between the displacement of the object and the initiation of the dogs’ search. In Experiment 1, during the delay, a barrier was placed between the dog and the apparatus. In Experiment 2, the lights were turned off during the delay. The search accuracy for some dogs was strongly affected by the delay, however, search accuracy for other dogs was not affected. These results suggest that although a perceptual/conditioning mechanism may be involved for some dogs, it cannot account for the performance of others. It is likely that these other dogs showed true object permanence. PMID:19520244

The expression of proinflammatory genes in epidermal keratinocytes is regulated by hydration status.

PubMed

Xu, Wei; Jia, Shengxian; Xie, Ping; Zhong, Aimei; Galiano, Robert D; Mustoe, Thomas A; Hong, Seok J

2014-04-01

Mucosal wounds heal more rapidly, exhibit less inflammation, and are associated with minimal scarring when compared with equivalent cutaneous wounds. We previously demonstrated that cutaneous epithelium exhibits an exaggerated response to injury compared with mucosal epithelium. We hypothesized that treatment of injured skin with a semiocclusive dressing preserves the hydration of the skin and results in a wound healing phenotype that more closely resembles that of mucosa. Here we explored whether changes in hydration status alter epidermal gene expression patterns in rabbit partial-thickness incisional wounds. Using microarray studies on injured epidermis, we showed that global gene expression patterns in highly occluded versus non-occluded wounds are distinct. Many genes including IL-1β, IL-8, TNF-α (tumor necrosis factor-α), and COX-2 (cyclooxygenase 2) are upregulated in non-occluded wounds compared with highly occluded wounds. In addition, decreased levels of hydration resulted in an increased expression of proinflammatory genes in human ex vivo skin culture (HESC) and stratified keratinocytes. Hierarchical analysis of genes using RNA interference showed that both TNF-α and IL-1β regulate the expression of IL-8 through independent pathways in response to reduced hydration. Furthermore, both gene knockdown and pharmacological inhibition studies showed that COX-2 mediates the TNF-α/IL-8 pathway by increasing the production of prostaglandin E2 (PGE2). IL-8 in turn controls the production of matrix metalloproteinase-9 in keratinocytes. Our data show that hydration status directly affects the expression of inflammatory signaling in the epidermis. The identification of genes involved in the epithelial hydration pathway provides an opportunity to develop strategies to reduce scarring and optimize wound healing.

On consistent inter-view synthesis for autostereoscopic displays

NASA Astrophysics Data System (ADS)

Tran, Lam C.; Bal, Can; Pal, Christopher J.; Nguyen, Truong Q.

2012-03-01

In this paper we present a novel stereo view synthesis algorithm that is highly accurate with respect to inter-view consistency, thus to enabling stereo contents to be viewed on the autostereoscopic displays. The algorithm finds identical occluded regions within each virtual view and aligns them together to extract a surrounding background layer. The background layer for each occluded region is then used with an exemplar based inpainting method to synthesize all virtual views simultaneously. Our algorithm requires the alignment and extraction of background layers for each occluded region; however, these two steps are done efficiently with lower computational complexity in comparison to previous approaches using the exemplar based inpainting algorithms. Thus, it is more efficient than existing algorithms that synthesize one virtual view at a time. This paper also describes the implementation of a simplified GPU accelerated version of the approach and its implementation in CUDA. Our CUDA method has sublinear complexity in terms of the number of views that need to be generated, which makes it especially useful for generating content for autostereoscopic displays that require many views to operate. An objective of our work is to allow the user to change depth and viewing perspective on the fly. Therefore, to further accelerate the CUDA variant of our approach, we present a modified version of our method to warp the background pixels from reference views to a middle view to recover background pixels. We then use an exemplar based inpainting method to fill in the occluded regions. We use warping of the foreground from the reference images and background from the filled regions to synthesize new virtual views on the fly. Our experimental results indicate that the simplified CUDA implementation decreases running time by orders of magnitude with negligible loss in quality. [Figure not available: see fulltext.

The Cricoid Force Necessary to Occlude the Esophageal Entrance: Is There a Gender Difference?

PubMed

Zeidan, Ahed M; Salem, M Ramez; Bamadhaj, Munir; Mazoit, Jean-Xavier; Sadek, Hussein; Houjairy, Hassan; Abdulkhaleq, Kamal; Bamadhaj, Nabil

2017-04-01

We tested the hypothesis whether gender differences exist in the applied cricoid force necessary to prevent regurgitation. Real-time visual and dynamic means were used to assess the effectiveness of different applied cricoid forces in occluding the esophageal entrance in men (group 1) and in women (group 2). In anesthetized and paralyzed patients, the glottis and esophageal entrance were visualized with a Glidescope video laryngoscope. Trained operators performed cricoid pressure (CP) and gastric tube insertion trials. Successful gastric tube insertion in the presence of CP was considered ineffective CP, whereas unsuccessful insertion was considered effective CP. The applied cricoid forces were measured with a novel instrument, the cricometer. The first patient in each group received 20 N. The applied cricoid force in successive patients was determined by the response of the previous patient within the same group, using the up-and-down sequential allocation technique. In the 30 men and 30 women who qualified for the study, the median cricoid force (cricoid force = 50) that occluded the esophageal entrance was 30.8 N (95% confidence interval = 28.15-33.5) in men, and 18.7 N in women (95% confidence interval = 17.1-20.3; P < .0001). Patency of the esophageal entrance was observed when CP was not applied and when inadequate forces that allowed successful esophageal cannulation were used. The current study provides evidence that the median force necessary to occlude the esophageal entrance to prevent regurgitation is less in women compared with men. Applying the appropriate cricoid force in women should also decrease airway-related problems that tend to occur with the use of excessive forces. The findings of the current study may only be applicable to patients with normal body habitus.

μ-PIV/Shadowgraphy measurements to elucidate dynamic physicochemical interactions in a multiphase model of pulmonary airway reopening

NASA Astrophysics Data System (ADS)

Yamaguchi, Eiichiro

2010-10-01

We employ micro-particle image velocimetry (μ-PIV) and shadowgraphy to measure the ensemble-averaged fluid-phase velocity field and interfacial geometry during pulsatile bubble propagation that includes a reverse-flow phase under influence of exogenous lung surfactant (Infasurf). Disease states such as respiratory distress syndrome (RDS) are characterized by insufficient pulmonary surfactant concentrations that enhance airway occlusion and collapse. Subsequent airway reopening, driven by mechanical ventilation, may generate damaging stresses that cause ventilator-induced lung injury (VILI). It is hypothesized that reverse flow may enhance surfactant uptake and protect the lung from VILI. The microscale observations conducted in this study will provide us with a significant understanding of dynamic physicochemical interactions that can be manipulated to reduce the magnitude of this damaging mechanical stimulus during airway reopening. Bubble propagation through a liquid-occluded fused glass capillary tube is controlled by linear-motor-driven syringe pumps that provide mean and sinusoidal velocity components. A translating microscope stage mechanically subtracts the mean velocity of the bubble tip in order to hold the progressing bubble tip in the microscope field of view. To optimize the signal-to-noise ratio near the bubble tip, μ-PIV and shadow images are recorded in separate trials then combined during post-processing with help of a custom-designed micro scale marker. Non-specific binding of Infasurf proteins to the channel wall is controlled by oxidation and chemical treatment of the glass surface. The colloidal stability and dynamic/static surface properties of the Infasurf-PIV particle solution are carefully adjusted based on Langmuir trough measurements. The Finite Time Lyapunov Exponent (FTLE) is computed to provide a Lagrangian perspective for comparison with our boundary element predictions.

Clinical efficiency and safety analysis of transcatheter closure of multiple atrial septal defects in adults.

PubMed

Song, Zhi-Yuan; He, Guo-Xiang; Shu, Mao-Qin; Hu, Hou-Yuan; Tong, Shi-Fei; Ran, Bo-Li; Liu, Jian-Ping; Li, Yong-Hua; Jing, Tao

2009-03-01

Transcatheter closure of atrial septal defects (ASDs) is currently a reliable alternative to surgery, even though challenging in patients with multiple ASDs. The aim of this study was to evaluate the clinical efficiency and safety of transcatheter closure in multiple ASDs. Multiple ASDs were diagnosed by transthoracic echocardiography (TTE) or transesophageal echocardiography (TEE). The occlusive condition and distance between 2 adjacent ASDs were measured by TTE examination. Then, the number and size of the occluder(s) was determined. TTE examinations were performed after transcatheter closure as follow-up. The transcatheter procedure was successful in 15 patients with multiple ASDs, using a single occluder in 9 patients and 2 occluders in the remaining 6 patients. Overall, 21 ASD occluders were implanted. During a follow-up period of 6 mo to 5 y, a slight residual shunt was found in 1 patient without any symptoms; a moderate residual shunt was identified at the inferior vena cava and the occluder was removed by surgery 1 mo after procedure. Other complications, including endocarditis, arrhythmia, thromboembolism, and atrioventricular valve damage were not recorded in any of the 15 patients during the follow-up period. Transcatheter closure of multiple ASDs is safe and efficient. Two occluders are necessary for the distance of 2 ASDs more than 7 mm, and a single occluder is sufficient for those 7 mm or less. Copyright (c) 2009 Wiley Periodicals, Inc.

The Woven EndoBridge (WEB) as primary treatment for unruptured intracranial aneurysms.

PubMed

van Rooij, Sanne Bt; van Rooij, Willem Jan; Peluso, Jo P; Sluzewski, Menno

2018-01-01

Purpose The intrasaccular flow disruptor Woven EndoBridge (WEB) device is developed for the treatment of wide-necked aneurysms without supportive devices. We used the WEB as primary treatment for unruptured aneurysms suitable for the device, regardless of neck size. Methods Between February 2015 and June 2017, 59 aneurysms in 51 patients were selectively treated with the WEB. There were 15 men and 36 women with a mean age of 59 years. Mean aneurysm size was 7.0 mm (range 3-22 mm). Of 59 aneurysms, 45 (76%) had a wide neck defined as ≥4 mm or dome-neck ratio ≤1.5. No stents or supporting balloons were used. Results Initial WEB position was judged good in all 59 unruptured aneurysms. One patient with a basilar tip aneurysm had a late thrombotic posterior cerebral artery occlusion by protrusion of the WEB over the artery. There were no procedural ruptures. Overall complication rate was 2.0% (1 of 51, 95% CI 0.01-11.3%). Imaging follow-up was available in 55 of 59 aneurysms (93%). At 3 months, 41 of 57 aneurysms (72%) were completely occluded, 12 (21%) had a neck remnant and 4 (7%) were incompletely occluded. Conclusion WEB treatment is safe and effective in selected unruptured aneurysms suitable for the device, regardless of neck size or location. There was no need for supportive devices. Three-quarters of all unruptured small aneurysms could be treated with the WEB. In our opinion, the WEB is a valuable alternative to coils, especially in wide-necked aneurysms.

Amodal causal capture in the tunnel effect.

PubMed

Bae, Gi Yeul; Flombaum, Jonathan I

2011-01-01

In addition to identifying individual objects in the world, the visual system must also characterize the relationships between objects, for instance when objects occlude one another or cause one another to move. Here we explored the relationship between perceived causality and occlusion. Can one perceive causality in an occluded location? In several experiments, observers judged whether a centrally presented event involved a single object passing behind an occluder, or one object causally launching another (out of view and behind the occluder). With no additional context, the centrally presented event was typically judged as a non-causal pass, even when the occluding and disoccluding objects were different colors--an illusion known as the 'tunnel effect' that results from spatiotemporal continuity. However, when a synchronized context event involved an unambiguous causal launch, participants perceived a causal launch behind the occluder. This percept of an occluded causal interaction could also be driven by grouping and synchrony cues in the absence of any explicitly causal interaction. These results reinforce the hypothesis that causality is an aspect of perception. It is among the interpretations of the world that are independently available to vision when resolving ambiguity, and that the visual system can 'fill in' amodally.

Use of intrathecal urokinase in repeated shunt and external ventricular drain blockage from high CSF protein due to an optic pathway glioma.

PubMed

Shooman, David; Vajramani, Girish V; Davidson, Jennifer; Sparrow, Owen C

2010-05-01

High cerebrospinal fluid (CSF) protein is a recognised association of optic pathway gliomas. This can occlude ventriculoperitoneal (VP) shunt catheters or external ventricular drains (EVD). We describe an 8-year-old boy with an optic pathway glioma, who had frequent episodes of a blocked VP shunt and EVD due to high CSF protein level. This responded favourably to repeated urokinase instillation into the catheter lumen. We present the course of treatment and the method of administration and review the literature behind thrombolytic therapy for occluded catheter devices. Intrathecal urokinase was effective in unblocking the EVD and lysing the protein clots within the ventricle. We found no previously published cases of intrathecal urokinase for this problem. This novel intervention seemed promising as a safe and effective means of maintaining EVD patency in cases complicated by excessive protein loads in CSF and hydrocephalus.

Forgetting Common Ground: Six- to Seven-Year-Olds Have an Overinterpretive Theory of Mind

ERIC Educational Resources Information Center

Lagattuta, Kristin Hansen; Sayfan, Liat; Blattman, Amanda J.

2010-01-01

Four- to 9-year-olds and adults (N = 256) viewed a series of pictures that were covered with occluders to reveal nondescript or identifiable parts. Participants predicted how 3 characters, 1 who had previously viewed the full picture and 2 who had not, would interpret the obstructed drawings. Results showed significant development between 4 and 9…

Does the Direction in Which a Figure Is Looking Influence Whether It Is Visible?

ERIC Educational Resources Information Center

McGuigan, Nicola

2009-01-01

Previous studies have shown that young preschool children are highly sensitive to mutual engagement and struggle to diagnose the visibility of a figure when their facial area is occluded. The present study aimed to explore the specificity of engagement by varying (a) the orientation of a figure relative to an observer and (b) the visible area of…

Thulium fiber laser induced vapor bubbles using bare, tapered, ball, hollow steel, and muzzle brake fiber optic tips

NASA Astrophysics Data System (ADS)

Gonzalez, David A.; Hardy, Luke A.; Hutchens, Thomas C.; Irby, Pierce B.; Fried, Nathaniel M.

2018-02-01

This study characterizes laser-induced vapor bubbles for five distal fiber optic tip configurations, to provide insight into stone retropulsion experienced during laser ablation of kidney stones. A TFL with 1908-nm wavelength delivered 34 mJ energy per pulse at 500-μs pulse duration through five different fibers: 100-μm-core/170-μm-OD bare fiber tip, 150-μm- to 300-μm-core tapered fiber tip, 100-μm-core/300-μm-OD ball tip fiber, 100-μm-core/340- μm-OD hollow steel tip fiber, and 100-μm-core/560-μm-OD muzzle brake fiber tip. A high speed camera with 10- μm spatial and 9.5-μs temporal resolution imaged vapor bubble dynamics. A needle hydrophone measured pressure transients in forward (0°) and side (90°) directions while placed at a 6.8 +/- 0.4 mm distance from fiber tip. Maximum bubble dimensions (width/length) averaged 0.7/1.5, 1.0/1.6, 0.5/1.1, 0.8/1.9, and 0.7/1.5 mm, for bare, tapered, ball, hollow steel, and muzzle tips, respectively (n=5). The hollow steel tip exhibited the most elongated vapor bubble shape, translating into increased forward pressure in this study and consistent with higher stone retropulsion in previous reports. Relative pressures (a.u.) in (forward/side) directions averaged 1.7/1.6, 2.0/2.0, 1.4/1.2, 6.8/1.1, and 0.3/1.2, for each fiber tip (n=5). For hollow steel tip, forward pressure was 4× higher than for bare fiber. For the muzzle brake fiber tip, forward pressure was 5× lower than for bare fiber. Bubble dimensions and pressure measurements demonstrated that the muzzle tip reduced forward pressure by partially venting vapors through side holes, consistent with lower stone retropulsion observed in previous reports.

Rotating coherent flow structures as a source for narrowband tip clearance noise from axial fans

NASA Astrophysics Data System (ADS)

Zhu, Tao; Lallier-Daniels, Dominic; Sanjosé, Marlène; Moreau, Stéphane; Carolus, Thomas

2018-03-01

Noise from axial fans typically increases significantly as the tip clearance is increased. In addition to the broadband tip clearance noise at the design flow rate, narrowband humps also associated with the tip flow are observed in the far-field acoustic spectra at lower flow rate. In this study, both experimental and numerical methods are used to shed more light on the noise generation mechanism of this narrowband tip clearance noise and provide a unified description of this source. Unsteady aeroacoustic predictions with the Lattice-Boltzmann Method (LBM) are successfully compared with experiment. Such a validation allows using LBM data to conduct a detailed modal analysis of the pressure field for detecting rotating coherent flow structures which might be considered as noise sources. As previously found in ring fans the narrowband humps in the far-field noise spectra are found to be related to the tip clearance noise that is generated by an interaction of coherent flow structures present in the tip region with the leading edge of the impeller blades. The visualization of the coherent structures shows that they are indeed part of the unsteady tip clearance vortex structures. They are hidden in a complex, spatially and temporally inhomogeneous flow field, but can be recovered by means of appropriate filtering techniques. Their pressure trace corresponds to the so-called rotational instability identified in previous turbomachinery studies, which brings a unified picture of this tip-noise phenomenon for the first time.

Visual Marking and Change Blindness: Moving Occluders and Transient Masks Neutralize Shape Changes to Ignored Objects

ERIC Educational Resources Information Center

Watson, Derrick G.; Kunar, Melina A.

2010-01-01

Visual search efficiency improves by presenting (previewing) one set of distractors before the target and remaining distractor items (D. G. Watson & G. W. Humphreys, 1997). Previous work has shown that this preview benefit is abolished if the old items change their shape when the new items are added (e.g., D. G. Watson & G. W. Humphreys,…

Confirmatory Factor Analysis of the Trinity Inventory of Precursors to Suicide (TIPS) and Its Relationship to Hopelessness and Depression

ERIC Educational Resources Information Center

Smyth, Caroline L.; MacLachlan, Malcolm

2005-01-01

Numerous existing measures assess attitudes toward suicide yet fail to account for contextual factors. The Trinity Inventory of Precursors to Suicide (TIPS) is presented as an alternative, with implications for the development of prevention programs. Having previously reported exploratory analysis of the TIPS; confirmatory factor analysis and…

Tips for giving a memorable presentation Part V: stage fright and rehearsing a presentation.

PubMed

Harolds, Jay A

2012-11-01

Previous articles in this series have included many tips on composing a memorable presentation. This article will focus on rehearsing the presentation and dealing with stage fright. There are additional comments on making sure everything is optimized in the lecture room in advance and other tips for the actual presentation.

The Role of Good Form in Young Infants' Perception of Partly Occluded Objects.

ERIC Educational Resources Information Center

Johnson, Scott P.; Bremner, J. Gavin; Slater, Alan M.; Mason, Uschi C.

2000-01-01

Three experiments investigated whether 4-month-olds would attend to and utilize the global configuration ("good form") of a partly occluded, moving object to perceive its unit and coherence behind the occluder. Results indicated that curvature per se provided information in support of completion, in addition to global configuration and…

Shape memory polymer foams for endovascular therapies

DOEpatents

Wilson, Thomas S.; Maitland, Duncan J.

2017-03-21

A system for occluding a physical anomaly. One embodiment comprises a shape memory material body wherein the shape memory material body fits within the physical anomaly occluding the physical anomaly. The shape memory material body has a primary shape for occluding the physical anomaly and a secondary shape for being positioned in the physical anomaly.

Shape memory polymer foams for endovascular therapies

DOEpatents

Wilson, Thomas S [Castro Valley, CA; Maitland, Duncan J [Pleasant Hill, CA

2012-03-13

A system for occluding a physical anomaly. One embodiment comprises a shape memory material body wherein the shape memory material body fits within the physical anomaly occluding the physical anomaly. The shape memory material body has a primary shape for occluding the physical anomaly and a secondary shape for being positioned in the physical anomaly.

Shape memory polymer foams for endovascular therapies

DOEpatents

Wilson, Thomas S.; Maitland, Duncan J.

2015-05-26

A system for occluding a physical anomaly. One embodiment comprises a shape memory material body wherein the shape memory material body fits within the physical anomaly occluding the physical anomaly. The shape memory material body has a primary shape for occluding the physical anomaly and a secondary shape for being positioned in the physical anomaly.

Onset and Offset as Determinants of the Simon Effect

ERIC Educational Resources Information Center

Riggio, Lucia; Gherri, Elena; Lupianez, Juan

2012-01-01

We investigated the presence and the characteristics of the Simon effect for onset and offset targets when these stimuli are randomly intermixed. In Experiment 1, two possible target locations were occupied by an occluder. On onset trials, a target appeared above an occluder, while on offset trials one of the occluders disappeared, revealing the…

Non-contact AFM measurement of the Hamaker constants of solids: Calibrating cantilever geometries.

PubMed

Fronczak, Sean G; Browne, Christopher A; Krenek, Elizabeth C; Beaudoin, Stephen P; Corti, David S

2018-05-01

Surface effects arising from roughness and deformation can negatively affect the results of AFM contact experiments. Using the non-contact portion of an AFM deflection curve is therefore desirable for estimating the Hamaker constant, A, of a solid material. A previously validated non-contact quasi-dynamic method for estimating A is revisited, in which the cantilever tip is now always represented by an "effective sphere". In addition to simplifying this previous method, accurate estimates of A can still be obtained even though precise knowledge of the nanoscale geometric features of the cantilever tip are no longer required. The tip's "effective" radius of curvature, R eff , is determined from a "calibration" step, in which the tip's deflection at first contact with the surface is measured for a substrate with a known Hamaker constant. After R eff is known for a given tip, estimates of A for other surfaces of interest are then determined. An experimental study was conducted to validate the new method and the obtained results are in good agreement with predictions from the Lifshitz approximation, when available. Since R eff accounts for all geometric uncertainties of the tip through a single fitted parameter, no visual fitting of the tip shape was required. Copyright © 2018 Elsevier Inc. All rights reserved.

Numerical investigation of tip clearance effects on the performance of ducted propeller

NASA Astrophysics Data System (ADS)

Ding, Yongle; Song, Baowei; Wang, Peng

2015-09-01

Tip clearance loss is a limitation of the improvement of turbomachine performance. Previous studies show the Tip clearance loss is generated by the leakage flow through the tip clearance, and is roughly linearly proportional to the gap size. This study investigates the tip clearance effects on the performance of ducted propeller. The investigation was carried out by solving the Navier-Stokes equations with the commercial Computational Fluid Dynamic (CFD) code CFX14.5. These simulations were carried out to determine the underlying mechanisms of the tip clearance effects. The calculations were performed at three different chosen advance ratios. Simulation results showed that the tip loss slope was not linearly at high advance due to the reversed pressure at the leading edge. Three type of vortical structures were observed in the tip clearance at different clearance size.

Sound from a Two-Blade Propeller at Supersonic Tip Speeds

NASA Technical Reports Server (NTRS)

Hubbard, Harvey H; Lassiter, Leslie W

1952-01-01

Report presents the results of sound measurements at static conditions made for a two-blade 47-inch-diameter propeller in the tip Mach number range 0.75 to 1.30. For comparison, spectrums have been obtained at both subsonic and supersonic tip speeds. In addition, the measured data are compared with calculations by the theory of Gutin which has previously been found adequate for predicting the sound at subsonic tip speeds. Curves are presented from which the maximum over-all noise levels in free space may be estimated if the power, tip Mach number, and distance are known.

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

Bahramipour, Phillip F.; Festa, Steven; Biswal, Rajiv

Though polycystic liver disease (PCLD) has historically been considered a contraindication to TIPS, we present a case where technically successful shunt creation was achieved without the need for modification of the standard TIPS procedure, as was required in a previous report.

Form Perception of Partly Occluded Shapes in 4-Month-Old Infants

ERIC Educational Resources Information Center

de Wit, Tessa C. J.; Vrins, Sven; Dejonckheere, Peter J. N.; van Lier, Rob

2008-01-01

Two habituation experiments were conducted to investigate how 4-month-old infants perceive partly occluded shapes. In the first experiment, we presented a simple, partly occluded shape to the infants until habituation was reached. Then we showed either a probable completion (one that would be predicted on the basis of both local and global cues)…

Cotton-Top Tamarins' ("Saguinus Oedipus") Expectations about Occluded Objects: A Dissociation between Looking and Reaching Tasks

ERIC Educational Resources Information Center

Santos, Laurie R.; Seelig, David; Hauser, Marc D.

2006-01-01

Recent work with human infants and toddlers suggests a dissociation between performance on looking and reaching tasks. Specifically, infants appear to generate accurate representations of occluded objects and their actions when tested in expectancy violation looking tasks but often fail to use this information when reaching for occluded objects.…

[Percutaneous closure of the patent ductus arteriosus in children with the Amplatzer Duct Occluder II].

PubMed

Parra-Bravo, José Rafael; Osuna-Izaguirre, Manuel Alfredo; Beirana-Palencia, Luisa; Gálvez-Cancino, Franco; Martínez-Monterrosas, Christian; Lazo-Cárdenas, César; Reyes-Vargas, César

2014-01-01

In the last decades, several devices have been used for the percutaneous closure of patent ductus arteriosus, with its own limitations and risks. The Amplatzer Duct Occluder II has been designed to overcome those limitations and reduce risks. We described our initial series of patients who underwent percutaneous closure of patent ductus arteriosus with the Amplatzer Duct Occluder II, emphasis on the technical aspects of the procedure. We reviewed the clinical records of 9 patients with patent ductus arteriosus who underwent percutaneous closure with the Amplatzer Duct Occluder II. Median age was 24 months (range 8-51 months) and the median weight was 10.7kg (range 6-16.3kg). The minimal ductus arteriosus diameter was 2.7mm (1-5mm). Implantation was successful in all cases. The devices most commonly used (33.3%) were the dimensions 4-4mm (3 patients), in 2 patients were used 3-4mm and in the rest of the patients were employed occluder other sizes. Four cases showed slight residual flow immediately after implantation. Total closure was achieved in 24h in 8 of 9 patients (89%). There was no embolization of the occluder or deaths during the procedure and we only observed one minor complication. The Amplatzer Duct Occluder II in this series was effective in 89% of the patients at 24hs after the procedure and 100% follow-up. The implantation was safe and no major complications were observed. The occlusion rate is comparable to those reported for the Amplatzer Duct Occluder I. Copyright © 2013 Instituto Nacional de Cardiología Ignacio Chávez. Published by Masson Doyma México S.A. All rights reserved.

Closure of large patent ductus arteriosus using the Amplatzer Septal Occluder.

PubMed

García-Montes, José A; Camacho-Castro, Anahí; Sandoval-Jones, Juan P; Buendía-Hernández, Alfonso; Calderón-Colmenero, Juan; Patiño-Bahena, Emilia; Zabal, Carlos

2015-03-01

Percutaneous closure of patent ductus arteriosus has become the treatment of choice in many centres. In patients with large ducts and pulmonary hypertension, transcatheter closure has been achieved with success using the Amplatzer Duct Occluder or even the Amplatzer Muscular Ventricular Septal Defect Occluder. We present a series of 17 patients with large and hypertensive ductus arteriosus who were treated with an Amplatzer Septal Occluder. The group had 11 female patients (64.7%) and a mean age of 18.6±12.1 years. The haemodynamic and anatomical data are as follows: pulmonary artery systolic pressure 71.3±31.8 mmHg, pulmonary to systemic flow ratio 3.14±1.36, ductal diameter at the pulmonary end 12.5±3.8 mm, and at the aortic end 20.2±7.7 mm; 14 cases (82.3%) had type A ducts. In 11 patients, we began the procedure using a different device - six with duct occluder and five with ventricular septal occluder - and it was changed because of device embolisation in six (35.3%). All septal occluders were delivered successfully. Residual shunt was moderate in six patients (35.3%), mild in eight (47%), trivial in two (11.8%), and no shunt in one (5.9%). Pulmonary systolic pressure decreased to 48.9±10.8 mmHg after occlusion (p=0.0015). Follow-up in 15 patients (88.2%) for 28.4±14.4 months showed complete closure in all cases but one, and continuous decrease of the pulmonary systolic pressure to 31.4±10.5 mmHg. No complications at follow-up have been reported. The Amplatzer Septal Occluder is a good alternative to percutaneously treat large and hypertensive ductus arteriosus.

Neural dynamics of 3-D surface perception: figure-ground separation and lightness perception.

PubMed

Kelly, F; Grossberg, S

2000-11-01

This article develops the FACADE theory of three-dimensional (3-D) vision to simulate data concerning how two-dimensional pictures give rise to 3-D percepts of occluded and occluding surfaces. The theory suggests how geometrical and contrastive properties of an image can either cooperate or compete when forming the boundary and surface representations that subserve conscious visual percepts. Spatially long-range cooperation and short-range competition work together to separate boundaries of occluding figures from their occluded neighbors, thereby providing sensitivity to T-junctions without the need to assume that T-junction "detectors" exist. Both boundary and surface representations of occluded objects may be amodally completed, whereas the surface representations of unoccluded objects become visible through modal processes. Computer simulations include Bregman-Kanizsa figure-ground separation, Kanizsa stratification, and various lightness percepts, including the Münker-White, Benary cross, and checkerboard percepts.

Forces and electronic transport in a contact formed by a graphene tip and a defective MoS2 monolayer: a theoretical study.

PubMed

di Felice, D; Dappe, Y J; González, C

2018-06-01

A theoretical study of a graphene-like tip used in atomic force microscopy (AFM) is presented. Based on first principles simulations, we proved the low reactivity of this kind of tip, using a MoS 2 monolayer as the testing sample. Our simulations show that the tip-MoS 2 interaction is mediated through weak van der Waals forces. Even on the defective monolayer, the interaction is reduced by one order of magnitude with respect to the values obtained using a highly reactive metallic tip. On the pristine monolayer, the S atoms were imaged for large distances together with the substitutional defects which should be observed as brighter spots in non-contact AFM measurements. This result is in contradiction with previous simulations performed with Cu or Si tips where the metallic defects were imaged for much larger distances than the S atoms. For shorter distances, the Mo sites will be brighter even though a vacancy is formed. On the other hand, the largest conductance value is obtained over the defect formed by two Mo atoms occupying a S divacancy when the half-occupied p y -states of the graphene-like tip find a better coupling with d-orbitals of the highest substitutional atom. Due to the weak interaction, no conductance plateau is formed in any of the sites. A great advantage of this tip lies in the absence of atomic transfer between the tip and the sample leading to a more stable AFM measurement. Finally, and as previously shown, we confirm the atomic resolution in a scanning tunneling microscopy simulation using this graphene-based tip.

Morphogenetic Implications of Peristalsis-Driven Fluid Flow in the Embryonic Lung

PubMed Central

Bokka, Kishore K.; Jesudason, Edwin C.; Lozoya, Oswaldo A.; Guilak, Farshid; Warburton, David; Lubkin, Sharon R.

2015-01-01

Epithelial organs are almost universally secretory. The lung secretes mucus of extremely variable consistency. In the early prenatal period, the secretions are of largely unknown composition, consistency, and flow rates. In addition to net outflow from secretion, the embryonic lung exhibits transient reversing flows from peristalsis. Airway peristalsis (AP) begins as soon as the smooth muscle forms, and persists until birth. Since the prenatal lung is liquid-filled, smooth muscle action can transport fluid far from the immediately adjacent tissues. The sensation of internal fluid flows has been shown to have potent morphogenetic effects, as has the transport of morphogens. We hypothesize that these effects play an important role in lung morphogenesis. To test these hypotheses in a quantitative framework, we analyzed the fluid-structure interactions between embryonic tissues and lumen fluid resulting from peristaltic waves that partially occlude the airway. We found that if the airway is closed, fluid transport is minimal; by contrast, if the trachea is open, shear rates can be very high, particularly at the stenosis. We performed a parametric analysis of flow characteristics' dependence on tissue stiffnesses, smooth muscle force, geometry, and fluid viscosity, and found that most of these relationships are governed by simple ratios. We measured the viscosity of prenatal lung fluid with passive bead microrheology. This paper reports the first measurements of the viscosity of embryonic lung lumen fluid. In the range tested, lumen fluid can be considered Newtonian, with a viscosity of 0.016 ± 0.008 Pa-s. We analyzed the interaction between the internal flows and diffusion and conclude that AP has a strong effect on flow sensing away from the tip and on transport of morphogens. These effects may be the intermediate mechanisms for the enhancement of branching seen in occluded embryonic lungs. PMID:26147967

Characterization of closely related delta-TIP genes encoding aquaporins which are differentially expressed in sunflower roots upon water deprivation through exposure to air.

PubMed

Sarda, X; Tousch, D; Ferrare, K; Cellier, F; Alcon, C; Dupuis, J M; Casse, F; Lamaze, T

1999-05-01

We isolated five sunflower (Helianthus annuus) cDNAs belonging to the TIP (tonoplast intrinsic protein) family. SunRb7 and Sun gammaTIP (partial sequence) are homologous to tobacco TobRb7 and Arabidopsis gamma-TIP, respectively. SunTIP7, 18 and 20 (SunTIPs) are closely related and homologous to Arabidopsis delta-TIP (SunTIP7 and 20 have already been presented in Sarda et al., Plant J. 12 (1997) 1103-1111). As was previously shown for SunTIP7 and 20, expression of SunTIP18 and SunRb7 in Xenopus oocytes caused an increase in osmotic water permeability demonstrating that they are aquaporins. In roots, in situ hybridization revealed that SunTIP7 and 18 mRNAs accumulate in phloem tissues. The expression of TIP-like genes was studied in roots during 24 h water deprivation through exposure to air. During the course of the treatment, each SunTIP gene displayed an individual response: SunTIP7 transcript abundance increased, SunTIP18 decreased whereas that of SunTIP20 was transitorily enhanced. By contrast, SunRb7 and Sun gammaTIP mRNA levels did not fluctuate. Due to the changes in their transcript levels, it is proposed that SUNTIP aquaporins encoded by delta-TIP-like genes play a role in the sunflower response to drought.

Progressive regression of intracranial arteriovenous malformations after Onyx embolization.

PubMed

Kocur, Damian; Przybyłko, Nikodem; Hofman, Mariusz; Jamróz, Tomasz; Doleżych, Hanna; Baron, Jan; Kwiek, Stanisław

Progressive regression of cerebral arteriovenous malformations (AVMs) is a rare phenomenon that may occur spontaneously or after previous surgical or endovascular incomplete obliteration. We present two cases of AVMs occluded partially with Onyx followed by the unexpected cure of the lesions with the angiographic evidences as well as multiannual follow-up. Copyright © 2017 Polish Neurological Society. Published by Elsevier Urban & Partner Sp. z o.o. All rights reserved.

Memory and prediction in natural gaze control

PubMed Central

Diaz, Gabriel; Cooper, Joseph; Hayhoe, Mary

2013-01-01

In addition to stimulus properties and task factors, memory is an important determinant of the allocation of attention and gaze in the natural world. One way that the role of memory is revealed is by predictive eye movements. Both smooth pursuit and saccadic eye movements demonstrate predictive effects based on previous experience. We have previously shown that unskilled subjects make highly accurate predictive saccades to the anticipated location of a ball prior to a bounce in a virtual racquetball setting. In this experiment, we examined this predictive behaviour. We asked whether the period after the bounce provides subjects with visual information about the ball trajectory that is used to programme the pursuit movement initiated when the ball passes through the fixation point. We occluded a 100 ms period of the ball's trajectory immediately after the bounce, and found very little effect on the subsequent pursuit movement. Subjects did not appear to modify their strategy to prolong the fixation. Neither were we able to find an effect on interception performance. Thus, it is possible that the occluded trajectory information is not critical for subsequent pursuit, and subjects may use an estimate of the ball's trajectory to programme pursuit. These results provide further support for the role of memory in eye movements. PMID:24018726

Thulium fiber laser-induced vapor bubble dynamics using bare, tapered, ball, hollow steel, and muzzle brake fiber optic tips

NASA Astrophysics Data System (ADS)

Gonzalez, David A.; Hardy, Luke A.; Hutchens, Thomas C.; Irby, Pierce B.; Fried, Nathaniel M.

2018-03-01

This study characterizes laser-induced vapor bubble dynamics for five different distal fiber optic tip configurations, to provide insight into stone retropulsion commonly experienced during laser ablation of kidney stones. A thulium fiber laser with 1908-nm wavelength delivered 34-mJ energy per pulse at 500-μs pulse duration through five different fibers such as 100-μm-core / 170-μm-OD bare fiber tip, 150- to 300-μm-core tapered fiber tip, 100-μm-core / 300-μm-OD ball tip fiber, 100-μm-core / 340-μm-OD hollow steel tip fiber, and 100-μm-core / 560-μm-OD muzzle brake fiber tip. A high-speed camera with 10-μm-spatial and 9.5-μs-temporal resolution was used to image the vapor bubble dynamics. A needle hydrophone measured pressure transients in the forward (0 deg) and side (90 deg) directions while placed at a 6.8 ± 0.4 mm distance from the distal fiber tip. Maximum bubble dimensions (width/length) averaged 0.7/1.5, 1.0/1.6, 0.5/1.1, 0.8/1.9, and 0.7 / 1.5 mm, for bare, tapered, ball, hollow steel, and muzzle brake fiber tips, respectively (n = 5). The hollow steel tip exhibited the most elongated vapor bubble shape, translating into increased forward pressure in this study and consistent with higher stone retropulsion in previous reports. Relative pressures (a.u.) in (forward/side) directions averaged 1.7/1.6, 2.0/2.0, 1.4/1.2, 6.8/1.1, and 0.3/1.2, for each fiber tip (n = 5). For the hollow steel tip, forward pressure was 4 × higher than for the bare fiber. For the muzzle brake fiber tip, forward pressure was 5 × lower than the bare fiber. Bubble dimensions and pressure measurements demonstrated that the muzzle brake fiber tip reduced forward pressure by partially venting vapors through the portholes, which is consistent with the observation of lower stone retropulsion in previous reports.

Phonation Threshold Pressure Measurement with a Semi-Occluded Vocal Tract

ERIC Educational Resources Information Center

Titze, Ingo R.

2009-01-01

Purpose: The purpose of this article was to determine if a semi-occluded vocal tract could be used to measure phonation threshold pressure. This is in contrast to the shutter technique, where an alternation between a fully occluded tract and an unoccluded tract is used. Method: Five male and 5 female volunteers phonated through a thin straw held…

Occlusion issues in early Renaissance art

PubMed Central

Gillam, Barbara

2011-01-01

Early Renaissance painters innovatively attempted to depict realistic three-dimensional scenes. A major problem was to produce the impression of overlap for surfaces that occlude one another in the scene but are adjoined in the picture plane. Much has been written about perspective in art but little about occlusion. Here I examine some of the strategies for depicting occlusion used by early Renaissance painters in relation to ecological considerations and perceptual research. Perceived surface overlap is often achieved by implementing the principle that an occluding surface occludes anything behind it, so that occlusion perception is enhanced by a lack of relationship of occluding contour to occluded contours. Some well-known figure-ground principles are also commonly used to stratify adjoined figures. Global factors that assist this stratification include the placement of figures on a ground plane, a high viewpoint, and figure grouping. Artists of this period seem to have differed on whether to occlude faces and heads, often carefully avoiding doing so. Halos were either eliminated selectively or placed oddly to avoid such occlusions. Finally, I argue that the marked intransitivity in occlusion by architecture in the paintings of Duccio can be related to the issue of perceptual versus cognitive influences on the visual impact of paintings. PMID:23145262

Chemically etched fiber tips for near-field optical microscopy: a process for smoother tips.

PubMed

Lambelet, P; Sayah, A; Pfeffer, M; Philipona, C; Marquis-Weible, F

1998-11-01

An improved method for producing fiber tips for scanning near-field optical microscopy is presented. The improvement consists of chemically etching quartz optical fibers through their acrylate jacket. This new method is compared with the previous one in which bare fibers were etched. With the new process the meniscus formed by the acid along the fiber does not move during etching, leading to a much smoother surface of the tip cone. Subsequent metallization is thus improved, resulting in better coverage of the tip with an aluminum opaque layer. Our results show that leakage can be avoided along the cone, and light transmission through the tip is spatially limited to an optical aperture of a 100-nm dimension.

Identification and characterization of steady and occluded water in drinking water distribution systems.

PubMed

Tong, Huiyan; Zhao, Peng; Zhang, Hongwei; Tian, Yimei; Chen, Xi; Zhao, Weigao; Li, Mei

2015-01-01

Deterioration and leakage of drinking water in distribution systems have been a major issue in the water industry for years, which are associated with corrosion. This paper discovers that occluded water in the scales of the pipes has an acidic environment and high concentration of iron, manganese, chloride, sulfate and nitrate, which aggravates many pipeline leakage accidents. Six types of water samples have been analyzed under the flowing and stagnant periods. Both the water in the exterior of the tubercles and stagnant water carry suspended iron particles, which explains the occurrence of "red water" when the system hydraulic conditions change. Nitrate is more concentrated in occluded water under flowing condition in comparison with that in flowing water. However, the concentration of nitrate in occluded water under stagnant condition is found to be less than that in stagnant water. A high concentration of manganese is found to exist in steady water, occluded water and stagnant water. These findings impact secondary pollution and the corrosion of pipes and containers used in drinking water distribution systems. The unique method that taking occluded water from tiny holes which were drilled from the pipes' exteriors carefully according to the positions of corrosion scales has an important contribution to research on corrosion in distribution systems. And this paper furthers our understanding and contributes to the growing body of knowledge regarding occluded environments in corrosion scales. Copyright © 2014 Elsevier Ltd. All rights reserved.

Safety, dose, and timing of reteplase in treating occluded central venous catheters in children with cancer.

PubMed

Terrill, Kelly R; Lemons, Richard S; Goldsby, Robert E

2003-11-01

Recombinant tissue plasminogen activator, alteplase, began to be commonly used to restore the patency of occluded central venous catheters (CVCs) as urokinase production was halted in the late 1990s. However, alteplase often requires an extended dwell time to restore patency to occluded CVCs. In adults, reteplase, a newer thrombolytic agent, has been reported to restore patency to CVCs in 30 minutes. The authors prospectively evaluated the safety and efficacy of reteplase in restoring patency to occluded CVCs in children with cancer. This was a dose escalation trial. The dose of reteplase was initiated at 0.1 units and increased by increments of 0.1 units to a maximum dose of 0.4 units. Each dose was tested on at least three participants. Time to patency after reteplase administration was recorded by nurses caring for the patients. Attempts to access the line occurred every 15 minutes for 1 hour. CVCs that remained occluded after 1 hour were treated with alteplase. Reteplase was administered to 15 clotted CVCs. Twelve of the 15 were cleared with an average dwell time of 38 minutes. The time to patency did not appear to correlate with the dose. No adverse events were reported. Reteplase can restore patency to occluded CVCs in a pediatric population. Reteplase appears to have comparable efficacy with alteplase, but reteplase may require shorter dwell times. A prospective, randomized, clinical trial is warranted to determine whether reteplase is as effective as alteplase in restoring patency to occluded CVCs.

[Right patent ductus arteriosus with an ipsilateral aortic arch: percutaneous closure with amplatzer devices].

PubMed

Santiago, Justo; Acuña, Manuel; Arispe, Elizabeth; Camargo, Ronaldo; Neves, Juliana; Arnoni, Daniel; Fontes, Valmir F; Pedra, Carlos A

2007-03-01

The association of a right aortic arch with an ipsilateral patent ductus arteriosus is rare, especially when there are no other intracardiac anomalies. We report three female patients aged 26, 35 and 9 years with this combination in whom previous attempts at surgical closure by thoracotomy and sternotomy were unsuccessful and who subsequently underwent successful percutaneous closure of the defects using Amplatzer devices. In two patients, although angiography demonstrated the presence of type-A patent ductus arteriosus, it was not possible to determine the minimum diameter accurately and it was necessary to measure it using a sizing balloon. An Amplatzer duct occluder was used in two patients and an Amplatzer muscular ventricular septal defect occluder, in the other. In all patients, full closure was confirmed in the catheterization laboratory and the patients were discharged on the same day with no complications. Percutaneous closure of a right patent ductus arteriosus associated with a right aortic arch is feasible, safe and effective.

The effect of concurrent hand movement on estimated time to contact in a prediction motion task.

PubMed

Zheng, Ran; Maraj, Brian K V

2018-04-27

In many activities, we need to predict the arrival of an occluded object. This action is called prediction motion or motion extrapolation. Previous researchers have found that both eye tracking and the internal clocking model are involved in the prediction motion task. Additionally, it is reported that concurrent hand movement facilitates the eye tracking of an externally generated target in a tracking task, even if the target is occluded. The present study examined the effect of concurrent hand movement on the estimated time to contact in a prediction motion task. We found different (accurate/inaccurate) concurrent hand movements had the opposite effect on the eye tracking accuracy and estimated TTC in the prediction motion task. That is, the accurate concurrent hand tracking enhanced eye tracking accuracy and had the trend to increase the precision of estimated TTC, but the inaccurate concurrent hand tracking decreased eye tracking accuracy and disrupted estimated TTC. However, eye tracking accuracy does not determine the precision of estimated TTC.

Transarterial Balloon-assisted Onyx Embolization of Intracranial Arteriovenous Malformations Using a Dual-lumen Balloon Microcatheter: Two Case Reports.

PubMed

Kim, Sang Heum; Kim, Tae Gon; Kong, Min Ho

2017-09-01

The Onyx system has been well established in recent years as a very important material in the treatment of arteriovenous malformations (AVMs). When using the Onyx, it is essential to wait for the creation of a plug around the tip of the catheter, which enables the effective forward penetration of Onyx. Recent reports have shown that the introduction of a dimethyl sulfoxide compatible dual-lumen balloon microcatheter improves the efficiency of AVM embolization. We report our recent experience of two cases of intracranial AVM embolization using Onyx and the transarterial balloon-assisted technique. In both cases, the procedures were successfully performed and the nidus of the AVM was totally occluded in a relatively short time. This technique may enable immediate forward flow and penetration of Onyx without concern about reflux. It may also reduce the procedure time and increase the angiographic occlusion rate. Navigation of the dual-lumen balloon microcatheter nevertheless remains a challenge.

Transarterial Balloon-assisted Onyx Embolization of Intracranial Arteriovenous Malformations Using a Dual-lumen Balloon Microcatheter: Two Case Reports

PubMed Central

Kim, Sang Heum; Kong, Min Ho

2017-01-01

The Onyx system has been well established in recent years as a very important material in the treatment of arteriovenous malformations (AVMs). When using the Onyx, it is essential to wait for the creation of a plug around the tip of the catheter, which enables the effective forward penetration of Onyx. Recent reports have shown that the introduction of a dimethyl sulfoxide compatible dual-lumen balloon microcatheter improves the efficiency of AVM embolization. We report our recent experience of two cases of intracranial AVM embolization using Onyx and the transarterial balloon-assisted technique. In both cases, the procedures were successfully performed and the nidus of the AVM was totally occluded in a relatively short time. This technique may enable immediate forward flow and penetration of Onyx without concern about reflux. It may also reduce the procedure time and increase the angiographic occlusion rate. Navigation of the dual-lumen balloon microcatheter nevertheless remains a challenge. PMID:29159158

SMART micro-scissors with dual motors and OCT sensors (Conference Presentation)

NASA Astrophysics Data System (ADS)

Yeo, Chaebeom; Jang, Seonjin; Park, Hyun-cheol; Gehlbach, Peter L.; Song, Cheol

2017-02-01

Various end-effectors of microsurgical instruments have been developed and studied. Also, many approaches to stabilize the tool-tip using robotics have been studied such as the steady hand robot system, Micron, and SMART system. In our previous study, the horizontal SMART micro-scissors with a common path swept source OCT distance and one linear piezoelectric (PZT) motor was demonstrated as a microsurgical system. Because the outer needle is connected with a mechanical handle and moved to engage the tool tip manually, the tool tip position is instantaneously changed during the engaging. The undesirable motion can make unexpected tissue damages and low surgical accuracy. In this study, we suggest a prototype horizontal SMART micro-scissors which has dual OCT sensors and two motors to improve the tremor cancellation. Dual OCT sensors provide two distance information. Front OCT sensor detects a distance from the sample surface to the tool tip. Rear OCT sensors gives current PZT motor movement, acting like a motor encoder. The PZT motor can compensate the hand tremor with a feedback loop control. The manual engaging of tool tip in previous SMART system is replaced by electrical engaging using a squiggle motor. Compared with previous study, this study showed better performance in the hand tremor reduction. From the result, the SMART with automatic engaging may become increasingly valuable in microsurgical instruments.

Forces and electronic transport in a contact formed by a graphene tip and a defective MoS2 monolayer: a theoretical study

NASA Astrophysics Data System (ADS)

di Felice, D.; Dappe, Y. J.; González, C.

2018-06-01

A theoretical study of a graphene-like tip used in atomic force microscopy (AFM) is presented. Based on first principles simulations, we proved the low reactivity of this kind of tip, using a MoS2 monolayer as the testing sample. Our simulations show that the tip–MoS2 interaction is mediated through weak van der Waals forces. Even on the defective monolayer, the interaction is reduced by one order of magnitude with respect to the values obtained using a highly reactive metallic tip. On the pristine monolayer, the S atoms were imaged for large distances together with the substitutional defects which should be observed as brighter spots in non-contact AFM measurements. This result is in contradiction with previous simulations performed with Cu or Si tips where the metallic defects were imaged for much larger distances than the S atoms. For shorter distances, the Mo sites will be brighter even though a vacancy is formed. On the other hand, the largest conductance value is obtained over the defect formed by two Mo atoms occupying a S divacancy when the half-occupied p y -states of the graphene-like tip find a better coupling with d-orbitals of the highest substitutional atom. Due to the weak interaction, no conductance plateau is formed in any of the sites. A great advantage of this tip lies in the absence of atomic transfer between the tip and the sample leading to a more stable AFM measurement. Finally, and as previously shown, we confirm the atomic resolution in a scanning tunneling microscopy simulation using this graphene-based tip.

Dynamic representation of partially occluded objects in primate prefrontal and visual cortex

PubMed Central

Choi, Hannah; Shea-Brown, Eric

2017-01-01

Successful recognition of partially occluded objects is presumed to involve dynamic interactions between brain areas responsible for vision and cognition, but neurophysiological evidence for the involvement of feedback signals is lacking. Here, we demonstrate that neurons in the ventrolateral prefrontal cortex (vlPFC) of monkeys performing a shape discrimination task respond more strongly to occluded than unoccluded stimuli. In contrast, neurons in visual area V4 respond more strongly to unoccluded stimuli. Analyses of V4 response dynamics reveal that many neurons exhibit two transient response peaks, the second of which emerges after vlPFC response onset and displays stronger selectivity for occluded shapes. We replicate these findings using a model of V4/vlPFC interactions in which occlusion-sensitive vlPFC neurons feed back to shape-selective V4 neurons, thereby enhancing V4 responses and selectivity to occluded shapes. These results reveal how signals from frontal and visual cortex could interact to facilitate object recognition under occlusion. PMID:28925354

Pan-nitinol occluder and special delivery device for closure of patent ductus arteriosus: a canine-model feasibility study.

PubMed

Jiang, Hai-bin; Bai, Yuan; Zong, Gang-jun; Han, Lin; Li, Wei-ping; Lu, Yang; Qin, Yong-wen; Zhao, Xian-xian

2013-01-01

The aim of this study was to evaluate a new type of occluder for patent ductus arteriosus. Patent ductus arteriosus was established in a canine model by anastomosing a length of autologous jugular vein to the descending aorta and the left pulmonary artery in an end-to-side fashion. Transcatheter closure of each patent ductus arteriosus was performed on 10 dogs, which were then monitored for as long as 6 months with aortography, echocardiography, and histologic evaluation. Transcatheter closure with use of the novel pan-nitinol device was successful in all canine models. Postoperative echocardiography showed that the location and shape of the occluders were normal, without any residual shunting. Further histologic evaluation confirmed that the occluder surface was completely endothelialized 3 months after implantation. Transcatheter patent ductus arteriosus closure with the pan-nitinol occluder can be performed safely and successfully in a canine model and shows good biological compatibility and low mortality rates.

Safety and efficacy of nano lamellar TiN coatings on nitinol atrial septal defect occluders in vivo.

PubMed

Zhang, Zhi xiong; Fu, Bu fang; Zhang, De yuan; Zhang, Zhi wei; Cheng, Yan; Sheng, Li yuan; Lai, Chen; Xi, Ting fei

2013-04-01

Atrial septal defect (ASD) occlusion devices made of nickel-titanium (NiTi) have a major shortcoming in that they release nickel into the body. We modified NiTi occluders using Arc Ion Plating technology. Nano lamellar titanium-nitrogen (TiN) coatings were formed on the surfaces of the occluders. The safety and efficacy of the modified NiTi occluders were evaluated in animal model. The results showed that 38 out of 39 rams (97%) survived at the end of the experiment. Fibrous capsules formed on the surfaces of the devices. Gradual endothelialization took place through the attachment of endothelial progenitor cells from the blood and the migration of endothelial cells from adjacent endocardium. The neo-endocardium formed more quickly in the coated group than in the uncoated group, as indicated by the evaluation of the six month study group. After TiN coating, there was no significant difference in endothelial cell cycle. TiN coating significantly reduced the release of nickel in both in vivo and in vitro indicating an improved biocompatibility of the nitinol ASD occluders. Superior and modified ASD occluders may provide a good choice for people with nickel allergies after sFDA registration, which is expected in one to two years. Copyright © 2012 Elsevier B.V. All rights reserved.

Occluded Brescia-Cimino Hemodialysis Fistulas: Endovascular Treatment with Both Brachial Arterial and Venous Access Using the Pull-Through Technique

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

Miyayama, Shiro; Matsui, Osamu; Taki, Keiichi

2005-12-15

We retrospectively evaluated the usefulness of both arterial and venous access with the pull-through technique in endovascular treatment of totally occluded Brescia-Cimino fistulas. We treated 26 patients (17 men, 9 women; age range 43-82 years, mean age 66 years) with occluded Brescia-Cimino fistulas. First, the occluded segment was traversed from the antegrade brachial arterial access using a microcatheter-guidewire system. Second, the vein was retrogradely punctured after confirmation of all diseased segments, and a 0.014- or 0.016-inch guidewire was pulled through the venous access when the occluded segment was long. All interventions including thrombolysis, thromboaspiration, angioplasty, and stent placement were performedmore » via the venous access. The occlusion was successfully crossed via the brachial arterial access in 23 patients (88%). In 2 patients it was done from the venous approach. In the remaining patient it was not possible to traverse the occluded segment. The pull-through technique was successful in all 19 attempts. Clinical success was achieved in 96%, the primary patency rates at 6, 12, and 18 months were 83%, 78%, and 69%, the primary assisted patency rates were 92%, 92%, and 72%, and the secondary patency rates were 92%, 92%, and 92%, respectively. Minor complications in 5 patients included venous perforation in 2 (8%), venous rupture in 1 (4%), and regional hematoma in 2 (8%). Our study suggests that endovascular treatments with both arterial and venous access using the pull-through technique are highly effective in restoring function in totally occluded Brescia-Cimino fistulas.« less

Dissociable Frontal Controls during Visible and Memory-guided Eye-Tracking of Moving Targets

PubMed Central

Ding, Jinhong; Powell, David; Jiang, Yang

2009-01-01

When tracking visible or occluded moving targets, several frontal regions including the frontal eye fields (FEF), dorsal-lateral prefrontal cortex (DLPFC), and Anterior Cingulate Cortex (ACC) are involved in smooth pursuit eye movements (SPEM). To investigate how these areas play different roles in predicting future locations of moving targets, twelve healthy college students participated in a smooth pursuit task of visual and occluded targets. Their eye movements and brain responses measured by event-related functional MRI were simultaneously recorded. Our results show that different visual cues resulted in time discrepancies between physical and estimated pursuit time only when the moving dot was occluded. Visible phase velocity gain was higher than that of occlusion phase. We found bilateral FEF association with eye-movement whether moving targets are visible or occluded. However, the DLPFC and ACC showed increased activity when tracking and predicting locations of occluded moving targets, and were suppressed during smooth pursuit of visible targets. When visual cues were increasingly available, less activation in the DLPFC and the ACC was observed. Additionally, there was a significant hemisphere effect in DLPFC, where right DLPFC showed significantly increased responses over left when pursuing occluded moving targets. Correlation results revealed that DLPFC, the right DLPFC in particular, communicates more with FEF during tracking of occluded moving targets (from memory). The ACC modulates FEF more during tracking of visible targets (likely related to visual attention). Our results suggest that DLPFC and ACC modulate FEF and cortical networks differentially during visible and memory-guided eye tracking of moving targets. PMID:19434603

HIV-1 Tat targets Tip60 to impair the apoptotic cell response to genotoxic stresses

PubMed Central

Col, Edwige; Caron, Cécile; Chable-Bessia, Christine; Legube, Gaelle; Gazzeri, Sylvie; Komatsu, Yasuhiko; Yoshida, Minoru; Benkirane, Monsef; Trouche, Didier; Khochbin, Saadi

2005-01-01

HIV-1 transactivator Tat uses cellular acetylation signalling by targeting several cellular histone acetyltransferases (HAT) to optimize its various functions. Although Tip60 was the first HAT identified to interact with Tat, the biological significance of this interaction has remained obscure. We had previously shown that Tat represses Tip60 HAT activity. Here, a new mechanism of Tip60 neutralization by Tat is described, where Tip60 is identified as a substrate for the newly reported p300/CBP-associated E4-type ubiquitin-ligase activity, and Tat uses this mechanism to induce the polyubiquitination and degradation of Tip60. Tip60 targeting by Tat results in a dramatic impairment of the Tip60-dependent apoptotic cell response to DNA damage. These data reveal yet unknown strategies developed by HIV-1 to increase cell resistance to genotoxic stresses and show a role of Tat as a modulator of cellular protein ubiquitination. PMID:16001085

An Infectious Pseudoaneurysm Caused by Ventricular Septal Defect Occluder in Patent Ductus Arteriosus Closure in a Two-Year-Old Child.

PubMed

Li, Dingyang; Qiu, Qiu; Jin, Jing; Zhang, Changdong; Wang, Lijun; Zhang, Gangcheng

2017-12-12

We present a case of an infectious pseudoaneurysm after patent ductus arteriosus (PDA) closure with a ventricular septal defect (VSD) occluder in a two-year-old child. The aneurysm grew rapidly but was successfully removed in time and the patient survived. To our knowledge, this is the first report of an infectious pseudoaneurysm caused by VSD occluder in PDA closure.

Late Intrahepatic Hematoma Complicating Transjugular Intrahepatic Portosystemic Shunt for Budd-Chiari Syndrome

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

Terreni, Natalia; Vangeli, Marcello; Raimondo, Maria Luisa

Late intrahepatic hematoma is a rare complication of the transjugular intrahepatic portosystemic shunt (TIPS) procedure. We describe a patient with Budd-Chiari syndrome (BCS), who presented with a large inrahepatic hematoma 13 days after TIPS. Review of the literature reveals only two previous cases, both occurring in patients with BCS and presenting after a similar time interval. This potentially serious complication appears to be specific for TIPS in BCS.

Comparison of three patent foramen ovale closure devices in a randomized trial (Amplatzer versus CardioSEAL-STARflex versus Helex occluder).

PubMed

Taaffe, Margaret; Fischer, Evelyn; Baranowski, Andreas; Majunke, Nicolas; Heinisch, Corinna; Leetz, Michaela; Hein, Ralph; Bayard, Yves; Büscheck, Franziska; Reschke, Madlen; Hoffmann, Ilona; Wunderlich, Nina; Wilson, Neil; Sievert, Horst

2008-05-01

This randomized trial compared procedural complications and 30-day clinical outcomes of 3 patent foramen ovale (PFO) closure devices (Amplatzer, Helex, and CardioSEAL-STARflex). It examined 660 patients (361 men, 299 women, mean age 49.3+/-1.9 years), with 220 patients per group. All patients had a history of paradoxical embolism. All PFO closures were successful technically. Exchange of devices for others was most frequently required for the Helex occluder (7 of 220) and 2 of 220 in either of the other groups. Three device embolizations in the Helex group were retrieved and replaced successfully. One patient with a Helex occluder developed a transient ischemic attack and recovered without treatment. A hemopericardium in that group was punctured without affecting the device. One tamponade in the Amplatzer group required surgical device explantation. In 8 of 660 patients in the CardioSEAL-STARflex group, thrombi resolved after anticoagulation. Sixteen patients (11 in the CardioSEAL-STARflex group, 3 in the Amplatzer group, and 2 in the Helex group) had episodes of atrial fibrillation. PFOs were closed completely in 143 of 220 patients (65%) in the Amplatzer group, 116 of 220 patients (52.7%) in the Helex group, and 137 of 220 patients (62.3%) in the CardioSEAL-STARflex group at 30 days with significant differences between the Helex and Amplatzer occluders (p=0.0005) and the Helex and CardioSEAL-STARflex occluders (p=0.0003). PFO closure can be performed safely with each device. In conclusion, the Helex occluder embolized more frequently. Device thrombus formation and paroxysmal atrial fibrillation were more common with the CardioSEAL-STARflex occluder.

Transcatheter closure of ventricular septal defects with nitinol wire occluders of type patent ductus arteriosus.

PubMed

Wierzyk, Arkadiusz; Szkutnik, Małgorzata; Fiszer, Roland; Banaszak, Paweł; Pawlak, Szymon; Białkowski, Jacek

2014-01-01

Ventricular septal defects closure (VSD) depending on the anatomy and clinical setting can be performed surgically or by a hybrid and transcatheter approach. Two cases of children with VSD will be presented. Patients' defects were closed with various types of occluders made of nitinol wire mesh occluder, patent ductus arteriosus (PDA) type. The first case was a 2.5-year-old boy after cardiosurgical correction of tetralogy of Fallot (TOF). After the procedure, a significant haemodynamic residual VSD was observed, which was not successfully closed during the subsequent reoperation. Despite pharmacological treatment, symptoms of heart failure were observed in this patient. In echocardiographic images the residual VSD was presented as a tunnel-like dissection of the ventricular septum (length 6 mm and diameter 3.4 mm). The defect was closed via arterial access with an Amplatzer Duct Occluder II (ADO II). The procedure was successfully performed without any medical complications. In this child, a significant shunt reduction and a noticeable improvement in the patient's clinical status and diminished symptoms of heart failure were noticed. The second patient was a 4-year-old girl suffering from a multi-perforated perimembranous VSD accompanied by a ventricular septal defect with aneurysm. The defect was closed by a venous approach with a PDA Cardio-O-Fix occluder (very similar to ADO I). No short-term or long-term complications were visible during or after the procedure. Only a mild residual shunt through the VSD was observed 6 months afterwards. Transcatheter VSD closure with a proper morphology, with occluders of type Amplatzer Duct Occluder ADO I or ADO II, constitutes a safe and effective therapeutic alternative.

Adherent Raindrop Modeling, Detectionand Removal in Video.

PubMed

You, Shaodi; Tan, Robby T; Kawakami, Rei; Mukaigawa, Yasuhiro; Ikeuchi, Katsushi

2016-09-01

Raindrops adhered to a windscreen or window glass can significantly degrade the visibility of a scene. Modeling, detecting and removing raindrops will, therefore, benefit many computer vision applications, particularly outdoor surveillance systems and intelligent vehicle systems. In this paper, a method that automatically detects and removes adherent raindrops is introduced. The core idea is to exploit the local spatio-temporal derivatives of raindrops. To accomplish the idea, we first model adherent raindrops using law of physics, and detect raindrops based on these models in combination with motion and intensity temporal derivatives of the input video. Having detected the raindrops, we remove them and restore the images based on an analysis that some areas of raindrops completely occludes the scene, and some other areas occlude only partially. For partially occluding areas, we restore them by retrieving as much as possible information of the scene, namely, by solving a blending function on the detected partially occluding areas using the temporal intensity derivative. For completely occluding areas, we recover them by using a video completion technique. Experimental results using various real videos show the effectiveness of our method.

Percutaneous closure of a post-traumatic ventricular septal defect with a patent ductus arteriosus occluder.

PubMed

Xi, Er-Ping; Zhu, Jian; Zhu, Shui-Bo; Yin, Gui-Lin; Liu, Yong; Dong, Yong-Qiang; Zhang, Yu; Xia, Feng

2012-11-01

Ventricular septal defects resulting from post-traumatic cardiac injury are very rare. Percutaneous closure has emerged as a method for treating this disorder. We wish to report our experience in three patients who underwent percutaneous closure of a post-traumatic ventricular septal defect with a patent ductus arteriosus occluder. We treated three patients with post-traumatic ventricular septal defects caused by stab wounds with knives. After the heart wound was repaired, patient examinations revealed ventricular septal defects with pulmonary/systemic flow ratios (Qp/Qs) of over 1.7. The post-traumatic ventricular septal defects were closed percutaneously with a patent ductus arteriosus occluder (Lifetech Scientific (Shenzhen) Co., LTD, Guangdong, China) utilizing standard techniques. Post-operative transthoracic echocardiography revealed no residual left-to-right shunt and indicated normal ventricular function. In addition, 320-slice computerized tomography showed that the occluder was well placed and exhibited normal morphology. Our experiences indicate that closure of a post-traumatic ventricular septal defect using a patent ductus arteriosus occluder is feasible, safe, and effective.

Percutaneous closure of a post-traumatic ventricular septal defect with a patent ductus arteriosus occluder

PubMed Central

Xi, Er-Ping; Zhu, Jian; Zhu, Shui-Bo; Yin, Gui-Lin; Liu, Yong; Dong, Yong-Qiang; Zhang, Yu; Xia, Feng

2012-01-01

OBJECTIVE: Ventricular septal defects resulting from post-traumatic cardiac injury are very rare. Percutaneous closure has emerged as a method for treating this disorder. We wish to report our experience in three patients who underwent percutaneous closure of a post-traumatic ventricular septal defect with a patent ductus arteriosus occluder. METHODS: We treated three patients with post-traumatic ventricular septal defects caused by stab wounds with knives. After the heart wound was repaired, patient examinations revealed ventricular septal defects with pulmonary/systemic flow ratios (Qp/Qs) of over 1.7. The post-traumatic ventricular septal defects were closed percutaneously with a patent ductus arteriosus occluder (Lifetech Scientific (Shenzhen) Co., LTD, Guangdong, China) utilizing standard techniques. RESULTS: Post-operative transthoracic echocardiography revealed no residual left-to-right shunt and indicated normal ventricular function. In addition, 320-slice computerized tomography showed that the occluder was well placed and exhibited normal morphology. CONCLUSION: Our experiences indicate that closure of a post-traumatic ventricular septal defect using a patent ductus arteriosus occluder is feasible, safe, and effective. PMID:23184204

Development and evaluation of needle trap device geometry and packing methods for automated and manual analysis.

PubMed

Warren, Jamie M; Pawliszyn, Janusz

2011-12-16

For air/headspace analysis, needle trap devices (NTDs) are applicable for sampling a wide range of volatiles such as benzene, alkanes, and semi-volatile particulate bound compounds such as pyrene. This paper describes a new NTD that is simpler to produce and improves performance relative to previous NTD designs. A NTD utilizing a side-hole needle used a modified tip, which removed the need to use epoxy glue to hold sorbent particles inside the NTD. This design also improved the seal between the NTD and narrow neck liner of the GC injector; therefore, improving the desorption efficiency. A new packing method has been developed and evaluated using solvent to pack the device, and is compared to NTDs prepared using the previous vacuum aspiration method. The slurry packing method reduced preparation time and improved reproducibility between NTDs. To evaluate the NTDs, automated headspace extraction was completed using benzene, toluene, ethylbenzene, p-xylene (BTEX), anthracene, and pyrene (PAH). NTD geometries evaluated include: blunt tip with side-hole needle, tapered tip with side-hole needle, slider tip with side-hole, dome tapered tip with side-hole and blunt with no side-hole needle (expanded desorptive flow). Results demonstrate that the tapered and slider tip NTDs performed with improved desorption efficiency. Copyright © 2011 Elsevier B.V. All rights reserved.

What do dogs know about hidden objects?

PubMed

Miller, Holly C; Rayburn-Reeves, Rebecca; Zentall, Thomas R

2009-07-01

Previous research has found that dogs will search accurately for an invisibly displaced object when the task is simplified and contextual ambiguity is eliminated [Doré, F.Y., Fiset, S., Goulet, S., Dumas, M.-C., Gagnon, S., 1996. Search behavior in cats and dogs: interspecific differences in working memory and spatial cognition. Animal Learning & Behavior 24, 142-149; Miller, H., Gipson, C., Vaughan, A., Rayburn-Reeves, R., Zentall, T.R., 2009. Object permanence in dogs: invisible displacement in a rotation task. Psychonomic Bulletin & Review 16 (1), 150-155]. For example, when an object is placed inside an occluder, one of which was attached to each end of a beam that could be rotated 90 degrees , dogs search inside of the appropriate occluder. The current research confirmed this finding and tested the possibility that the dogs were using a perceptual/conditioning mechanism (i.e., their gaze was drawn to the occluder as the object was placed inside and they continued looking at it as it rotated). The test was done by introducing a delay between the displacement of the object and the initiation of the dogs' search. In Experiment 1, during the delay, a barrier was placed between the dog and the apparatus. In Experiment 2, the lights were turned off during the delay. The search accuracy for some dogs was strongly affected by the delay, however, search accuracy for other dogs was not affected. These results suggest that although a perceptual/conditioning mechanism may be involved for some dogs, it cannot account for the performance of others. It is likely that these other dogs showed true object permanence.

Transcatheter Closure of Bilateral Multiple Huge Pulmonary Arteriovenous Malformations with Homemade Double-Umbrella Occluders

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

Zhong Hongshan, E-mail: zhonghongshan@hotmail.com; Xu Ke; Shao Haibo

2008-07-15

A 28-year-old man underwent successful transcatheter occlusion of three huge pulmonary arteriovenous malformations (PAVMs) using homemade double-umbrella occluders and stainless steel coils. Thoracic CT with three-dimensional reconstruction and pulmonary angiography were used for treatment planning and follow-up. The diameters of the feeding vessels were 11 mm, 13 mm, and 14 mm, respectively. This report demonstrates the novel design and utility of the double-umbrella occluder, an alternative tool for treatment of large PAVMs.

Intracellular chloride ion concentration in differentiating neuronal cell and its role in growing neurite

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

Nakajima, Ken-ichi; Marunaka, Yoshinori; Department of Bio-Ionomics, Kyoto Prefectural University of Medicine, Graduate School of Medical Science, Kyoto 602-8566

Chloride ion (Cl{sup −}) is one of the most abundant anions in our body. Increasing evidence suggests that Cl{sup −} plays fundamental roles in various cellular functions. We have previously reported that electroneutral cation-chloride cotransporters, such as Na{sup +}-K{sup +}-2Cl{sup −} cotransporter 1 (NKCC1) and K{sup +}-Cl{sup −} cotransporter 1 (KCC1), are involved in neurite outgrowth during neuronal differentiation. In the present study, we studied if there is correlation between intracellular Cl{sup −} concentrations ([Cl{sup −}]{sub i}) and the length of growing neurites. We measured [Cl{sup −}]{sub i} in the cell body and growing neurite tips using halide-sensitive fluorescent dyemore » N-(ethoxycarbonylmethyl)-6-methoxyquinolinium bromide (MQAE), revealing that [Cl{sup −}]{sub i} in the tip of growing neurite was higher than that in cell body in a single cell. Importantly, there was a significant positive correlation between the length of growing neurite and [Cl{sup −}]{sub i} in neurite tip. Bumtanide (BMT), an inhibitor of NKCC1, significantly inhibited neurite outgrowth and decreased [Cl{sup −}]{sub i} in neurite tip. The results obtained in the present study and our previous studies together strongly suggest that high [Cl{sup −}]{sub i} in neurite tip region is crucial for efficient neurite outgrowth. - Highlights: • Intracellular Cl{sup −} concentrations ([Cl{sup −}]{sub i}) in the tip of growing neurite is higher than that in cell body in a single cell. • There is a significant positive correlation between the length of growing neurite and [Cl{sup −}]{sub i} in neurite tip. • Bumetanide significantly inhibits neurite outgrowth and decreased [Cl{sup −}]{sub i} in neurite tip. • High [Cl{sup −}]{sub i} in neurite tip region is crucial for efficient neurite outgrowth.« less

A singular case of asphyxia by choking on a handkerchief: accidental event or suicide to "shut-up" spirits.

PubMed

De Donno, A; Marrone, M; Santoro, V; Ostuni, A; Cassano, A; Grattagliano, I; Introna, F

2017-01-01

Choking in adults can prove fatal, despite resuscitation attempts. The manner of death can be natural, homicide or accident. When a death is due to choking, one must consider what conditions contributed to or predisposed the person to choking (eg. alcohol, drugs and physical and mental impairments). Homicidal deaths by choking are relatively uncommon, being more frequently accidental. The diagnosis of death by choking is made at autopsy when the airway is found occluded. If the individual had an occluded airway and the object or food was removed during resuscitation, the only way to make the diagnosis would be on the history. Here, we present a case of asphyxia (accidental or suicidal) by choking on a handkerchief in a patient with a long history of schizophrenia. The woman had attempted a previous suicide driven by evil spirits coming from inside her body, especially from the head and throat; in order to "shut-up" the spirit, she was trying to suffocate it with her hands or by a belt from her pants.

Application of two-dimensional unsteady aerodynamic to a free-tip rotor response analysis

NASA Technical Reports Server (NTRS)

Yates, L.; Kumagai, H.

1985-01-01

The free-tip rotor utilizes a rotor blade tip which is structurally decoupled from the blade inboard section. The tip is free to pitch about its own pitch axis to respond to the local flow angularity changes. The tip also experiences the heaving motion due to the flapping of the rotor blade. For an airfoil in any pitching and heaving motion which can be expanded into a Fourier series, the lift and moment calculated by Theodoren's theory is simply the linear combination of the lift and moment calculated for each harmonic. These lift and moment are then used to determine the response of the free-tip rotor. A parametric study is performed to determine the effect of mechanical damping, mechanical spring, sweep, friction, and a constant control moment on the free-tip rotor response characteristics and the resulting azimuthal lift distributions. The results showed that the free-tip has the capability to suppress the oscillatory lift distribution around the azimuth and to eliminate a significant negative life peak on the advancing tip. This result agrees with the result of the previous analysis based on the steady aerodynamics.

Is it necessary to occlude the ear in bone-conduction testing at 4 kHz, in order to prevent air-borne radiation affecting the results?

PubMed

Tate Maltby, Maryanne; Gaszczyk, David

2015-01-01

To re-evaluate the current BSA recommendation that the test ear should be occluded during the bone-conduction procedure at frequencies above 2 kHz to prevent audible air-borne radiation. Pure-tone audiometry was undertaken during routine hearing tests. The audiograms of fifty-two ears met the criteria for the study and were included. Bone conduction at 4 kHz was tested in three different conditions: test ear open/occluded by earplug and occluded by circumaural earphone. Forty-four adults aged 41-77 years with average hearing levels from normal to severe loss. All complied fully with the test procedure. No audiogram had a significant conductive element. There was no significant difference in each of the three test situations. Only two audiograms showed any (5 dB) difference at 4 kHz when bone conduction was retested with the ear occluded. The errors that result in a false air-bone gap at 4 kHz would not appear to be due to air-borne radiation. Failure to occlude the ear canal at 4 kHz, where air-borne radiation is greatest, makes no significant difference to the audiometric results. It is therefore suggested that it is unnecessary to block the test ear during routine pure-tone bone-conduction testing to prevent audible air-borne radiation, and that this should no longer form part of normal clinical practice.

Comparative scanning electron microscope analysis of diode laser and desensitizing toothpastes for evaluation of efficacy of dentinal tubular occlusion.

PubMed

Reddy, Guntakala Vikram; Akula, Sushma; Malgikar, Suryakanth; Babu, Palaparthy Raja; Reddy, Gooty Jagadish; Josephin, Johnson Juliet

2017-01-01

The present study aims to evaluate the efficacy of diode laser alone and in combination with desensitizing toothpastes in occluding dentinal tubules (both partially occluded and completely occluded tubules) by scanning electron microscope (SEM). Fifty human teeth were extracted, cervical cavities were prepared and etched with 17% ethylenediaminetetraacetic acid, and smear layer was removed to expose the tubules. The teeth were divided into five groups: Group I - Application of NovaMin-formulated toothpaste, Group II - Application of Pro-Argin ™ -formulated toothpaste, Group III - Application of diode laser in noncontact mode, Group IV - NovaMin-formulated toothpaste followed by laser irradiation, and Group V - Pro-Argin ™ -formulated toothpaste followed by laser irradiation. After treatment, quantitative analysis of occluded dentinal tubules was done by SEM analysis. The mean values of percentages of total occlusion of dentinal tubules in Groups I, II, III, IV, and V were 92.73% ± 1.38, 90.67% ± 1.86, 96.57% ± 0.64, 97.3% ± 0.68, and 96.9% ± 6.08, respectively. Addition of diode laser (Groups III, IV, and V) yielded a significant occlusion of the dentinal tubules when compared to desensitizing toothpastes alone (Groups I and II). Diode laser (Group III) has shown more efficacy in occluding dentinal tubules when compared with desensitizing toothpastes which was statistically significant ( P < 0.05). Among the five groups, NovaMin + diode laser (Group IV) showed the highest percentage of occluded dentinal tubules.

Amodal representation of occluded surfaces: role of invisible stimuli in apparent motion correspondence.

PubMed

Shimojo, S; Nakayama, K

1990-01-01

A series of demonstrations were created where the perceived depth of targets was controlled by stereoscopic disparity. A closer object (a cloud) was made to jump back and forth horizontally, partially occluding a farther object (a full moon). The more distant moon appeared stationary even though the unoccluded portion of it, a crescent, changed position. Reversal of the relative depth of the moon and cloud gave a totally different percept: the crescent appeared to flip back and forth in the front depth plane. Thus, the otherwise-robust apparent motion of the moon crescents was completely abolished in the cloud-closer case alone. This motion-blocking effect is attributed to the 'amodal presence' of the occluded surface continuing behind the occluding surface. To measure the effect of this occluded 'invisible' surface quantitatively, a bistable apparent motion display was used (Ramachandran and Anstis 1983a): two small rectangular-shaped targets changed their positions back and forth between two frames, and the disparity of a large centrally positioned rectangle was varied. When the perceived depths supported the possibility of amodal completion behind the large rectangle, increased vertical motion of the targets was found, suggesting that the amodal presence of the targets behind the occluder had effectively changed the center position of the moving targets for purposes of motion correspondence. Amodal contours are literally 'invisible', yet it is hypothesized that they have a neural representation at sufficiently early stages of visual processing to alter the correspondence solving process for apparent motion.

Diagenetic patterns and pore space distribution along a platform to outer-shelf transect (Urgonian limestone, Barremian-Aptian, SE France)

NASA Astrophysics Data System (ADS)

Léonide, Philippe; Fournier, François; Reijmer, John J. G.; Vonhof, Hubert; Borgomano, Jean; Dijk, Jurrien; Rosenthal, Maelle; van Goethem, Manon; Cochard, Jean; Meulenaars, Karlien

2014-06-01

The Urgonian limestones of Late Barremian/Early Aptian from Provence (SE, France) are characterized by the occurrence of microporous limestones at regional scale alternating with tight carbonates. This study, based on petrographical (sediment texture, facies) and diagenetical analyses (cement stratigraphy, porosity and isotope geochemistry) of more than 800 limestone samples provides insight into the parameters controlling the genesis, preservation or occlusion of microporosity along an inner platform to outer shelf transect. The tight and microporous Urgonian limestones from Provence can be grouped into 5 rock-types based on textures, associated depositional environments, porosity and pore-type, being: (1) tight inner-platform: TIP; (2) porous inner platform: PIP; (3) tight outer platform: TOP; (4) porous outer platform: POP and (5) tight outer shelf: TOS. In tight (TIP, TOP and TOS types) limestones intergranular and intragranular pore spaces were entirely occluded by early marine and/or early meteoric cementation, whereas in microporous (PIP, POP) limestones a significant fraction of the intergranular macroporosity was preserved during early and shallow burial diagenesis. Micrite neomorphism (hybrid Ostwald ripening process) occurred during meteoric shallow burial diagenesis in PIP and POP limestones during the regional Durancian Uplift event (Albian-Lower Cenomanian). This process resulted in microporosity enhancement and preservation. Circulation of meteoric fluids during exhumation produces intercrystalline microporosity enhancement and moldic porosity development. The present study documents the important role that both early diagenetic and depositional cycles and long-term tectonic processes have on pore space evolution and distribution in Mesozoic platform carbonates.

Toward Understanding Tip Leakage Flows in Small Compressor Cores Including Stator Leakage Flow

NASA Technical Reports Server (NTRS)

Berdanier, Reid A.; Key, Nicole L.

2017-01-01

The focus of this work was to provide additional data to supplement the work reported in NASA/CR-2015-218868 (Berdanier and Key, 2015b). The aim of that project was to characterize the fundamental flow physics and the overall performance effects due to increased rotor tip clearance heights in axial compressors. Data have been collected in the three-stage axial research compressor at Purdue University with a specific focus on analyzing the multistage effects resulting from the tip leakage flow. Three separate rotor tip clearances were studied with nominal tip clearance gaps of 1.5 percent, 3.0 percent, and 4.0 percent based on a constant annulus height. Overall compressor performance was previously investigated at four corrected speedlines (100 percent, 90 percent, 80 percent, and 68 percent) for each of the three tip clearance configurations. This study extends the previously published results to include detailed steady and time-resolved pressure data at two loading conditions, nominal loading (NL) and high loading (HL), on the 100 percent corrected speedline for the intermediate clearance level (3.0 percent). Steady detailed radial traverses of total pressure at the exit of each stator row are supported by flow visualization techniques to identify regions of flow recirculation and separation. Furthermore, detailed radial traverses of time-resolved total pressures at the exit of each rotor row have been measured with a fast-response pressure probe. These data were combined with existing three-component velocity measurements to identify a novel technique for calculating blockage in a multistage compressor. Time-resolved static pressure measurements have been collected over the rotor tips for all rotors with each of the three tip clearance configurations for up to five loading conditions along the 100 percent corrected speedline using fast-response piezoresistive pressure sensors. These time-resolved static pressure measurements reveal new knowledge about the trajectory of the tip leakage flow through the rotor passage. Further, these data extend previous measurements identifying a modulation of the tip leakage flow due to upstream stator wake propagation. Finally, a novel instrumentation technique has been implemented to measure pressures in the shrouded stator cavities. These data provide boundary conditions relating to the flow across the shrouded stator knife seal teeth. Moreover, the utilization of fast-response pressure sensors provides a new look at the time-resolved pressure field, leading to instantaneous differential pressures across the seal teeth. Ultimately, the data collected for this project represent a unique data set which contributes to build a better understanding of the tip leakage flow field and its associated loss mechanisms. These data will facilitate future engine design goals leading to small blade heights in the rear stages of high pressure compressors and aid in the development of new blade designs which are desensitized to the performance penalties attributed to rotor tip leakage flows.

Effects of dorzolamide on choroidal blood flow, ciliary blood flow, and aqueous production in rabbits.

PubMed

Reitsamer, Herbert A; Bogner, Barbara; Tockner, Birgit; Kiel, Jeffrey W

2009-05-01

To determine the effects of topical dorzolamide (a carbonic anhydrase inhibitor) on choroidal and ciliary blood flow and the relationship between ciliary blood flow and aqueous flow. The experiments were performed in four groups of pentobarbital-anesthetized rabbits treated with topical dorzolamide (2%, 50 microL). In all groups, intraocular pressure (IOP) and mean arterial pressure (MAP) at the eye level were measured continuously by direct cannulation. In group 1, aqueous flow was measured by fluorophotometry before and after dorzolamide treatment. In group 2, aqueous flow was measured after dorzolamide at normal MAP and while MAP was held constant at 80, 55, or 40 mm Hg with occluders on the aorta and vena cava. In group 3, the same MAP levels were used, and ciliary blood flow was measured transsclerally by laser Doppler flowmetry (LDF). In group 4, choroidal blood flow was measured by LDF with the probe tip positioned in the vitreous over the posterior pole during ramp increases and decreases in MAP before and after dorzolamide. Dorzolamide lowered IOP by 19% (P < 0.01) and aqueous flow by 17% (P < 0.01), and increased ciliary blood flow by 18% (P < 0.01), which was associated with a significant reduction in ciliary vasculature resistance (-7%, P < 0.01). Dorzolamide shifted the relationship between ciliary blood flow and aqueous flow downward relative to the previously determined control relationship in the rabbit. Dorzolamide did not alter choroidal blood flow, choroidal vascular resistance, or the choroidal pressure flow relationship. Acute topical dorzolamide is a ciliary vasodilator and has a direct inhibitory effect on aqueous production, but it does not have a detectable effect on choroidal hemodynamics at the posterior pole in the rabbit.

Superficial Palmar Arch Aneurysm after Carpal Tunnel Decompression, a Rare Complication: A Case Report

PubMed Central

Gull, S.; Spence, R. A. J.; Loan, W.

2011-01-01

False aneurysms of the palmar arteries are rare. They are usually associated with traumatic injuries to the hand vasculature. We present a case of superficial palmar arch aneurysm (SPAA), complicating carpal tunnel decompression which presented as a pulsatile mass at the site of previous surgery. Initial diagnosis was made on clinical examination and confirmed on doppler ultrasound (US) and computed tomographic angiography (CTA). The feeding vessel of the aneurysm was subsequently occluded using coil embolization. PMID:21547251

Conflicting Selection Pressures Will Constrain Viral Escape from Interfering Particles: Principles for Designing Resistance-Proof Antivirals.

PubMed

Rast, Luke I; Rouzine, Igor M; Rozhnova, Ganna; Bishop, Lisa; Weinberger, Ariel D; Weinberger, Leor S

2016-05-01

The rapid evolution of RNA-encoded viruses such as HIV presents a major barrier to infectious disease control using conventional pharmaceuticals and vaccines. Previously, it was proposed that defective interfering particles could be developed to indefinitely control the HIV/AIDS pandemic; in individual patients, these engineered molecular parasites were further predicted to be refractory to HIV's mutational escape (i.e., be 'resistance-proof'). However, an outstanding question has been whether these engineered interfering particles-termed Therapeutic Interfering Particles (TIPs)-would remain resistance-proof at the population-scale, where TIP-resistant HIV mutants may transmit more efficiently by reaching higher viral loads in the TIP-treated subpopulation. Here, we develop a multi-scale model to test whether TIPs will maintain indefinite control of HIV at the population-scale, as HIV ('unilaterally') evolves toward TIP resistance by limiting the production of viral proteins available for TIPs to parasitize. Model results capture the existence of two intrinsic evolutionary tradeoffs that collectively prevent the spread of TIP-resistant HIV mutants in a population. First, despite their increased transmission rates in TIP-treated sub-populations, unilateral TIP-resistant mutants are shown to have reduced transmission rates in TIP-untreated sub-populations. Second, these TIP-resistant mutants are shown to have reduced growth rates (i.e., replicative fitness) in both TIP-treated and TIP-untreated individuals. As a result of these tradeoffs, the model finds that TIP-susceptible HIV strains continually outcompete TIP-resistant HIV mutants at both patient and population scales when TIPs are engineered to express >3-fold more genomic RNA than HIV expresses. Thus, the results provide design constraints for engineering population-scale therapies that may be refractory to the acquisition of antiviral resistance.

Anterior chamber angle assessment using gonioscopy and ultrasound biomicroscopy.

PubMed

Narayanaswamy, Arun; Vijaya, Lingam; Shantha, B; Baskaran, Mani; Sathidevi, A V; Baluswamy, Sukumar

2004-01-01

Comparison of anterior chamber angle measurements using ultrasound biomicroscopy (UBM) and gonioscopy. Five hundred subjects were evaluated for grading of angle width by the Shaffer method. UBM was done in the same group to document angle width, angle opening distance (AOD 500), and anterior chamber depth. Biometric parameters were documented in all subjects. UBM and gonioscopic findings were compared. A study was conducted in 282 men and 218 women with a mean age of 57.32 +/- 12.48 years. Gonioscopic grading was used to segregate occludable (slit-like, grades 1 and 2) from nonoccludable (grades 3 and 4) angles. Subjective assessment by gonioscopy resulted in an overestimation of angle width within the occludable group when compared with values obtained by UBM. This did not affect the segregation of occludable versus nonoccludable angles by gonioscopy. Biometric parameters in eyes with occludable angles were significantly lower in comparison with eyes with nonoccludable angles, except for lens thickness. AOD 500 correlated well with angle width. We concluded that clinical segregation into occludable and nonoccludable angles by an experienced observer using gonioscopy is fairly accurate. However, UBM is required for objective quantification of angles, and AOD 500 can be a reliable and standard parameter to grade angle width.

A unified computational model of the development of object unity, object permanence, and occluded object trajectory perception.

PubMed

Franz, A; Triesch, J

2010-12-01

The perception of the unity of objects, their permanence when out of sight, and the ability to perceive continuous object trajectories even during occlusion belong to the first and most important capacities that infants have to acquire. Despite much research a unified model of the development of these abilities is still missing. Here we make an attempt to provide such a unified model. We present a recurrent artificial neural network that learns to predict the motion of stimuli occluding each other and that develops representations of occluded object parts. It represents completely occluded, moving objects for several time steps and successfully predicts their reappearance after occlusion. This framework allows us to account for a broad range of experimental data. Specifically, the model explains how the perception of object unity develops, the role of the width of the occluders, and it also accounts for differences between data for moving and stationary stimuli. We demonstrate that these abilities can be acquired by learning to predict the sensory input. The model makes specific predictions and provides a unifying framework that has the potential to be extended to other visual event categories. Copyright © 2010 Elsevier Inc. All rights reserved.

Focus information is used to interpret binocular images

PubMed Central

Hoffman, David M.; Banks, Martin S.

2011-01-01

Focus information—blur and accommodation—is highly correlated with depth in natural viewing. We examined the use of focus information in solving the binocular correspondence problem and in interpreting monocular occlusions. We presented transparent scenes consisting of two planes. Observers judged the slant of the farther plane, which was seen through the nearer plane. To do this, they had to solve the correspondence problem. In one condition, the two planes were presented with sharp rendering on one image plane, as is done in conventional stereo displays. In another condition, the planes were presented on two image planes at different focal distances, simulating focus information in natural viewing. Depth discrimination performance improved significantly when focus information was correct, which shows that the visual system utilizes the information contained in depth-of-field blur in solving binocular correspondence. In a second experiment, we presented images in which one eye could see texture behind an occluder that the other eye could not see. When the occluder's texture was sharp along with the occluded texture, binocular rivalry was prominent. When the occluded and occluding textures were presented with different blurs, rivalry was significantly reduced. This shows that blur aids the interpretation of scene layout near monocular occlusions. PMID:20616139

Methods for Improving the Curvature of Steerable Needles in Biological Tissue

PubMed Central

Adebar, Troy K.; Greer, Joseph D.; Laeseke, Paul F.; Hwang, Gloria L.; Okamura, Allison M.

2016-01-01

Robotic needle steering systems have the potential to improve percutaneous interventions such as radiofrequency ablation of liver tumors, but steering techniques described to date have not achieved sufficiently small radius of curvature in biological tissue to be relevant to this application. In this work, the impact of tip geometry on steerable needle curvature is examined. Finite-element simulations and experiments with bent-tip needles in ex vivo liver tissue demonstrate that selection of tip length and angle can greatly improve curvature, with radius of curvature below 5 cm in liver tissue possible through judicious selection of these parameters. Motivated by the results of this analysis, a new articulated-tip steerable needle is described, in which a distal section is actively switched by a robotic system between a straight tip (resulting in a straight path) and a bent tip (resulting in a curved path). This approach allows the tip length and angle to be increased, while the straight configuration allows the needle tip to still pass through an introducer sheath and rotate inside the body. Validation testing in liver tissue shows that the new articulated-tip steerable needle achieves smaller radius of curvature compared to bent-tip needles described in previous work. Steerable needles with optimized tip parameters, which can generate tight curves in liver tissue, increase the clinical relevance of needle steering to percutaneous interventions. PMID:26441438

Modulating p56Lck in T-Cells by a Chimeric Peptide Comprising Two Functionally Different Motifs of Tip from Herpesvirus saimiri

PubMed Central

Vernot, Jean-Paul; Perdomo-Arciniegas, Ana María; Pérez-Quintero, Luis Alberto; Martínez, Diego Fernando

2015-01-01

The Lck interacting protein Tip of Herpesvirus saimiri is responsible for T-cell transformation both in vitro and in vivo. Here we designed the chimeric peptide hTip-CSKH, comprising the Lck specific interacting motif CSKH of Tip and its hydrophobic transmembrane sequence (hTip), the latter as a vector targeting lipid rafts. We found that hTip-CSKH can induce a fivefold increase in proliferation of human and Aotus sp. T-cells. Costimulation with PMA did not enhance this proliferation rate, suggesting that hTip-CSKH is sufficient and independent of further PKC stimulation. We also found that human Lck phosphorylation was increased earlier after stimulation when T-cells were incubated previously with hTip-CSKH, supporting a strong signalling and proliferative effect of the chimeric peptide. Additionally, Lck downstream signalling was evident with hTip-CSKH but not with control peptides. Importantly, hTip-CSKH could be identified in heavy lipid rafts membrane fractions, a compartment where important T-cell signalling molecules (LAT, Ras, and Lck) are present during T-cell activation. Interestingly, hTip-CSKH was inhibitory to Jurkat cells, in total agreement with the different signalling pathways and activation requirements of this leukemic cell line. These results provide the basis for the development of new compounds capable of modulating therapeutic targets present in lipid rafts. PMID:26539553

Modulating p56Lck in T-Cells by a Chimeric Peptide Comprising Two Functionally Different Motifs of Tip from Herpesvirus saimiri.

PubMed

Vernot, Jean-Paul; Perdomo-Arciniegas, Ana María; Pérez-Quintero, Luis Alberto; Martínez, Diego Fernando

2015-01-01

The Lck interacting protein Tip of Herpesvirus saimiri is responsible for T-cell transformation both in vitro and in vivo. Here we designed the chimeric peptide hTip-CSKH, comprising the Lck specific interacting motif CSKH of Tip and its hydrophobic transmembrane sequence (hTip), the latter as a vector targeting lipid rafts. We found that hTip-CSKH can induce a fivefold increase in proliferation of human and Aotus sp. T-cells. Costimulation with PMA did not enhance this proliferation rate, suggesting that hTip-CSKH is sufficient and independent of further PKC stimulation. We also found that human Lck phosphorylation was increased earlier after stimulation when T-cells were incubated previously with hTip-CSKH, supporting a strong signalling and proliferative effect of the chimeric peptide. Additionally, Lck downstream signalling was evident with hTip-CSKH but not with control peptides. Importantly, hTip-CSKH could be identified in heavy lipid rafts membrane fractions, a compartment where important T-cell signalling molecules (LAT, Ras, and Lck) are present during T-cell activation. Interestingly, hTip-CSKH was inhibitory to Jurkat cells, in total agreement with the different signalling pathways and activation requirements of this leukemic cell line. These results provide the basis for the development of new compounds capable of modulating therapeutic targets present in lipid rafts.

Safety and efficacy of transcatheter closure of large patent ductus arteriosus in adults with a self-expandable occluder.

PubMed

Yu, Man-Li; Huang, Xin-Miao; Wang, Jia-Feng; Qin, Yong-Wen; Zhao, Xian-Xian; Zheng, Xing

2009-11-01

Most occurrences of large patent ductus arteriosus (PDAs) of > or =10 mm have been surgically closed, and transcatheter closure of these large PDAs was only reported in a few case reports. The present study reviewed our experience in transcatheter closure of such large PDAs with a Chinese self-expandable occluder, which is similar to but much cheaper than the Amplatzer occluder. From July 2000 to January 2008, 23 patients underwent transcatheter closure of large PDA > or =10 mm with this kind of occluder. The mean (SD) age of the patients was 38.0 (15.6) years (range 18-75 years). Radiographs of the chest, electrocardiograms, and echocardiograms were used for follow-up evaluation of the treatment within 1 day, 1 month, 6 months, and then every year after successful closure. The mean (SD) angiographic PDA diameter was 12.8 (2.6) mm (range 10-18 mm) and the mean occluder diameter was 18.0 (2.9) mm (range 16-22 mm). The occluders were delivered successfully and closed the PDA completely in 19 out of the 23 patients. Pulmonary arterial pressures decreased significantly after occlusion in patients with successful treatment: 67.3 (24.7) mmHg (range 29-122 mmHg) before occlusion and 42.3 (22.0) mmHg (range 19-98 mmHg) immediately after the procedure. Radiographs of the chest and echocardiograms showed that the diameters of the left atrium, left ventricle, and the main pulmonary artery decreased, and the ejection fraction (EF) increased at a mean (SD) follow-up of 36.3 (18.7) months (range 6-72 months). No severe complication occurred. The immediate and long-term outcomes suggested that transcatheter closure of PDAs with the native PDA occluder is a safe and effective treatment for adults with large PDA > or =10 mm.

Inward open characterization of EmrD transporter with molecular dynamics simulation

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

Tan, Xianwei; Wang, Boxiong, E-mail: boxiong_wang@yahoo.com

EmrD is a member of the multidrug resistance exporter family. Up to now, little is known about the structural dynamics that underline the function of the EmrD protein in inward-facing open state and how the EmrD transits from an occluded state to an inward open state. For the first time the article applied the AT simulation to investigate the membrane transporter protein EmrD, and described the dynamic features of the whole protein, the domain, the helices, and the amino acid residues during an inward-open process from its occluded state. The gradual inward-open process is different from the current model ofmore » rigid-body domain motion in alternating-access mechanism. Simulation results show that the EmrD inward-open conformational fluctuation propagates from a C-terminal domain to an N-terminal domain via the linker region during the transition from its occluded state. The conformational fluctuation of the C-terminal domain is larger than that of the N-terminal domain. In addition, it is observed that the helices exposed to the surrounding membrane show a higher level of flexibility than the other regions, and the protonated E227 plays a key role in the transition from the occluded to the open state. -- Highlights: •This study described the dynamic features of the whole EmrD protein, during an inward-open process from its occluded state. •The EmrD inward-open conformational fluctuation propagates from a C-terminal domain to an N-terminal domain via the linker region during the transition from its occluded state. •The conformational fluctuation of the C-terminal domain is larger than that of the N-terminal domain. •The protonated E227 plays a key role in the transition from the occluded to the open state.« less

A Taxonomy of 3D Occluded Objects Recognition Techniques

NASA Astrophysics Data System (ADS)

Soleimanizadeh, Shiva; Mohamad, Dzulkifli; Saba, Tanzila; Al-ghamdi, Jarallah Saleh

2016-03-01

The overall performances of object recognition techniques under different condition (e.g., occlusion, viewpoint, and illumination) have been improved significantly in recent years. New applications and hardware are shifted towards digital photography, and digital media. This faces an increase in Internet usage requiring object recognition for certain applications; particularly occulded objects. However occlusion is still an issue unhandled, interlacing the relations between extracted feature points through image, research is going on to develop efficient techniques and easy to use algorithms that would help users to source images; this need to overcome problems and issues regarding occlusion. The aim of this research is to review recognition occluded objects algorithms and figure out their pros and cons to solve the occlusion problem features, which are extracted from occluded object to distinguish objects from other co-existing objects by determining the new techniques, which could differentiate the occluded fragment and sections inside an image.

Comparative scanning electron microscope analysis of diode laser and desensitizing toothpastes for evaluation of efficacy of dentinal tubular occlusion

PubMed Central

Reddy, Guntakala Vikram; Akula, Sushma; Malgikar, Suryakanth; Babu, Palaparthy Raja; Reddy, Gooty Jagadish; Josephin, Johnson Juliet

2017-01-01

Background: The present study aims to evaluate the efficacy of diode laser alone and in combination with desensitizing toothpastes in occluding dentinal tubules (both partially occluded and completely occluded tubules) by scanning electron microscope (SEM). Materials and Methods: Fifty human teeth were extracted, cervical cavities were prepared and etched with 17% ethylenediaminetetraacetic acid, and smear layer was removed to expose the tubules. The teeth were divided into five groups: Group I – Application of NovaMin-formulated toothpaste, Group II – Application of Pro-Argin™-formulated toothpaste, Group III – Application of diode laser in noncontact mode, Group IV – NovaMin-formulated toothpaste followed by laser irradiation, and Group V – Pro-Argin™-formulated toothpaste followed by laser irradiation. After treatment, quantitative analysis of occluded dentinal tubules was done by SEM analysis. Results: The mean values of percentages of total occlusion of dentinal tubules in Groups I, II, III, IV, and V were 92.73% ± 1.38, 90.67% ± 1.86, 96.57% ± 0.64, 97.3% ± 0.68, and 96.9% ± 6.08, respectively. Addition of diode laser (Groups III, IV, and V) yielded a significant occlusion of the dentinal tubules when compared to desensitizing toothpastes alone (Groups I and II). Conclusion: Diode laser (Group III) has shown more efficacy in occluding dentinal tubules when compared with desensitizing toothpastes which was statistically significant (P < 0.05). Among the five groups, NovaMin + diode laser (Group IV) showed the highest percentage of occluded dentinal tubules. PMID:29398853

Closure of the patent ductus arteriosus with the Amplatzer Duct Occluder II: a clinical experience.

PubMed

Karagöz, Tevfik; Akin, Alper; Ertuğrul, Ilker; Aykan, Hayrettin Hakan; Alehan, Dursun; Ozer, Sema; Ozkutlu, Süheyla

2012-12-01

The aim of our study was to share our clinical experience on cases with patent ductus arteriosus treated with the Amplatzer Duct Occluder II. Between 2008 and 2012, 26 of 31 patients with patent ductus arteriosus underwent successful transcatheter closure of patent ductus arteriosus using the Amplatzer Duct Occluder II. Mean age was 3.3 years and mean weight was 15.7 kilograms. The presence of a residual shunt, left pulmonary artery or aortic obstruction was explored by administering contrast material during the procedure. The patients were discharged 24 hours after the procedure. The procedure was successful in 26 of 31 patients and failed in five patients. According to the Krichenko classification, 26 patients had type A, one patient had type B and 4 patients had type C ductus. The mean narrowest ductus diameter was 3.2 mm and the mean ductus length was 6.7 mm. Complete angiographic occlusion occurred immediately after the procedure in 22 out of 26 patients in whom the ductus was closed successfully with the Amplatzer Duct Occluder II. Complete occlusion was achieved in the remaining patients with residual shunt one month after the procedure. The procedure was preceded by closure with an Amplatzer Duct Occluder I in two patients and an Amplatzer Vascular Plug I in one patient. Amplatzer Duct Occluder II is highly effective in transcatheter closure of patent ductus arteriosus. We think that an alternative closure device and alternative techniques can be attempted in patients with type C ductus. The success rate could increase with accumulating experience.

The possible involvement of root-cap mucilage in gravitropism and calcium movement across root tips of Allium cepa L

NASA Technical Reports Server (NTRS)

Moore, R.; Fondren, W. M.

1986-01-01

Roots of Allium cepa L. grown in aerated water elongate rapidly, but are not graviresponsive. These roots (1) possess extensive columella tissues comprised of cells containing numerous sedimented amyloplasts, (2) lack mucilage on their tips, and (3) are characterized by a weakly polar movement of calcium (Ca) across their tips. Placing roots in humid air correlates positively with the (1) onset of gravicurvature, (2) appearance of mucilage on tips of the roots, and (3) onset of the ability to transport Ca polarly to the lower side of the root tip. Gravicurvature of roots previously submerged in aerated water is more rapid when roots are oriented vertically for 1-2 h in humid air prior to being oriented horizontally. The more rapid gravicurvature of these roots correlates positively with the accumulation of mucilage at the tips of roots during the time the roots are oriented vertically. Therefore, the onset of gravicurvature and the ability of roots to transport Ca to the lower sides of their tips correlate positively with the presence of mucilage at their tips. These results suggest that mucilage may be important for the transport of Ca across root caps.

Identifying tips for intramolecular NC-AFM imaging via in situ fingerprinting

NASA Astrophysics Data System (ADS)

Sang, Hongqian; Jarvis, Samuel P.; Zhou, Zhichao; Sharp, Peter; Moriarty, Philip; Wang, Jianbo; Wang, Yu; Kantorovich, Lev

2014-10-01

A practical experimental strategy is proposed that could potentially enable greater control of the tip apex in non-contact atomic force microscopy experiments. It is based on a preparation of a structure of interest alongside a reference surface reconstruction on the same sample. Our proposed strategy is as follows. Spectroscopy measurements are first performed on the reference surface to identify the tip apex structure using a previously collected database of responses of different tips to this surface. Next, immediately following the tip identification protocol, the surface of interest is studied (imaging, manipulation and/or spectroscopy). The prototype system we choose is the mixed Si(111)-7×7 and surface which can be prepared on the same sample with a controlled ratio of reactive and passivated regions. Using an ``in silico'' approach based on ab initio density functional calculations and a set of tips with varying chemical reactivities, we show how one can perform tip fingerprinting using the Si(111)-7×7 reference surface. Then it is found by examining the imaging of a naphthalene tetracarboxylic diimide (NTCDI) molecule adsorbed on surface that negatively charged tips produce the best intramolecular contrast attributed to the enhancement of repulsive interactions.

On occlusal forces in dentitions with implant-supported fixed cantilever prostheses.

PubMed

Falk, H

1990-01-01

The main aims of this thesis were (1) to study the functional characteristics of dentitions with mandibular implant-supported fixed cantilever prostheses - IFCP s- occluding with complete dentures, (2) to study in detail the magnitudes and distributions of axially directed closing and chewing forces in such dentitions, (3) to study the influence of number and distribution of occlusal contacts on the magnitude and distribution of closing and chewing forces, (4) to assess the vertical bending moment and the resulting vertical bending stress in the cantilever joints and (5) to find out whether the force distribution over the cantilever beams and the resulting vertical bending stress in the cantilever joint are influenced by the type of prosthetic construction in the opposing jaw. Closing and chewing forces were registered in altogether seventeen subjects by means of miniature strain gauge transducers mounted bilaterally and symmetrically in performed matrices in prosthetic appliances. Four, six or eight transducers, evenly distributed over the tooth-arch, permitted registrations of axially directed occlusal forces in several occluding areas simultaneously. In Papers I-IV, the implant-supported prostheses were installed in the mandible and occluded with complete dentures. In Paper V, group A, the fixture-supported prostheses were installed in the maxilla and occluded with tooth-supported fixed partial dentures whereas in group B, the arrangements were analogous to those in Papers I-IV. All subjects exhibited a rhythmic chewing pattern and preferred one side for chewing although both sides were used. Most chewing sequences were terminated with swallowing with occlusal force development. The mean total forces acting over the tooth-arch varied somewhat between groups and occlusal arrangements but averaged 350 and 170 N for closing and chewing respectively. Closing and chewing forces increased distally along the cantilever beams when occluding with complete dentures and decreased distally when occluding with fixed partial dentures. The distally increasing force distribution pattern could be altered to a distally decreasing force distribution pattern by infraoccluding the second cantilever unit by as little as 100 microns. Calculated vertical bending moments and stresses in the cantilever joints of the preferred chewing sides created by closing and chewing forces were larger in dentitions where the IFCP occluded with a complete denture than in dentitions where the IFCP occluded with a tooth-supported fixed partial denture.

Blur and the perception of depth at occlusions.

PubMed

Zannoli, Marina; Love, Gordon D; Narain, Rahul; Banks, Martin S

2016-01-01

The depth ordering of two surfaces, one occluding the other, can in principle be determined from the correlation between the occlusion border's blur and the blur of the two surfaces. If the border is blurred, the blurrier surface is nearer; if the border is sharp, the sharper surface is nearer. Previous research has found that observers do not use this informative cue. We reexamined this finding. Using a multiplane display, we confirmed the previous finding: Our observers did not accurately judge depth order when the blur was rendered and the stimulus presented on one plane. We then presented the same simulated scenes on multiple planes, each at a different focal distance, so the blur was created by the optics of the eye. Performance was now much better, which shows that depth order can be reliably determined from blur information but only when the optical effects are similar to those in natural viewing. We asked what the critical differences were in the single- and multiplane cases. We found that chromatic aberration provides useful information but accommodative microfluctuations do not. In addition, we examined how image formation is affected by occlusions and observed some interesting phenomena that allow the eye to see around and through occluding objects and may allow observers to estimate depth in da Vinci stereopsis, where one eye's view is blocked. Finally, we evaluated how accurately different rendering and displaying techniques reproduce the retinal images that occur in real occlusions. We discuss implications for computer graphics.

Dentinal tubules occluded by bioactive glass-containing toothpaste exhibit high resistance toward acidic soft drink challenge.

PubMed

Bakri, M M; Hossain, M Z; Razak, F A; Saqina, Z H; Misroni, A A; Ab-Murat, N; Kitagawa, J; Saub, R B

2017-06-01

Dentine hypersensitivity is a common problem attributed by patent dentinal tubules. Ingredients incorporated in toothpastes aim to occlude patent dentinal tubules to minimize the dentine hypersensitivity. However, frequent consumption of acidic soft drinks may reverse the dentinal tubules' occlusion. In this in vitro study, the efficacy of dentinal tubules occluded by commercially available toothpastes to withstand different durations of an acidic soft drink challenge was investigated. One hundred and twenty dentine discs were divided into three groups. The discs from each group were brushed with toothpaste containing bioactive glass, arginine and control toothpaste. Each group was then divided into four subgroups and exposed to acidic soft drink over four different time durations. The scoring and the percentage of occluded dentinal tubules by Novamin-containing toothpaste was significantly better compared with arginine or the control toothpaste. Acidic soft drink challenge reduced the extent of dentinal tubules occlusion along with time. Dentinal tubules occluded by Novamin-containing toothpaste withstand the acidic challenge comparatively for a longer period. The findings demonstrated that occlusion of dentinal tubules is more efficient by the bioactive glass-containing toothpaste and thus may contribute to its better resistance to acidic soft drink challenge. © 2016 Australian Dental Association.

Previous tip moth infestation predispose trees to heavier attacks in subsequent generations

Treesearch

Anthony R. Coody; Christopher J. Fettig; John T. Nowak; C. Wayne Berisford

2000-01-01

The Nantucket pine tip moth, Rhyacionia frustrana (Comstock) (Lepidoptera: Tortricidae), is a common regeneration pest of pine plantations in the southeastern U.S.A. The insect has two to five generations annually depending on climate (Fettig et al. 1999a, USDA For. Serv. Res. Pap., In press). Following oviposition and eclosion, first-instar larvae...

Physcomitrella patens: a model for tip cell growth and differentiation.

PubMed

Vidali, Luis; Bezanilla, Magdalena

2012-12-01

The moss Physcomitrella patens has emerged as an excellent model system owing to its amenability to reverse genetics. The moss gametophyte has three filamentous tissues that grow by tip growth: chloronemata, caulonemata, and rhizoids. Because establishment of the moss plant relies on this form of growth, it is particularly suited for dissecting the molecular basis of tip growth. Recent studies demonstrate that a core set of actin cytoskeletal proteins is essential for tip growth. Additional actin cytoskeletal components are required for modulating growth to produce caulonemata and rhizoids. Differentiation into these cell types has previously been linked to auxin, light and nutrients. Recent studies have identified that core auxin signaling components as well as transcription factors that respond to auxin or nutrient levels are required for tip-growing cell differentiation. Future studies may establish a connection between the actin cytoskeleton and auxin or nutrient-induced cell differentiation. Copyright © 2012 Elsevier Ltd. All rights reserved.

An Optimization of Electrochemical Etching Conditions for Gold Nanotips Fabrication

NASA Astrophysics Data System (ADS)

Oh, Min Woo; Chong, Haeeun; Park, Doo Jae; Jang, Moonkyu; Bahn, Sebin; Choi, Soo Bong

2018-05-01

We demonstrate a series of experiments to find optimized electrochemical etching condition for fabricating gold nanotip, using square-wave voltage as a bias and using hydrochloric acid diluted by acetone as an etchant. We confirmed that the dilution ratio of 3: 1 between hydrochloric acid and acetone give the smallest tip apex diameter which reproduces our previous result. More importantly, by varying applied bias condition and immersion depth of the platinum ring used as a cathode inside the etchant, we found that the smaller tip apex diameter is achieved when both the amplitude and duty cycle get higher. The success rate, which we define the number of tips having meaningfully less diameter out of total number of tried tips, is also discussed.

Distribution and Determinants of Myocardial Perfusion Grade Following Late Mechanical Recanalization of Occluded Infarct-Related Arteries Postmyocardial Infarction: A Report From the Occluded Artery Trial

PubMed Central

Jorapur, Vinod; Steigen, Terje K.; Buller, Christopher E.; Dẑavík, Vladimír; Webb, John G.; Strauss, Bradley H.; Yeoh, Eunice E.S.; Kurray, Peter; Sokalski, Leszek; Machado, Mauricio C.; Kronsberg, Shari S.; Lamas, Gervasio A.; Hochman, Judith S.; John Mancini, G.B.

2010-01-01

Objective To evaluate the distribution and determinants of myocardial perfusion grade (MPG) following late recanalization of persistently occluded infarct-related arteries (IRA). Background MPG reflects microvascular integrity. It is an independent prognostic factor following myocardial infarction, but has been studied mainly in the setting of early reperfusion. The occluded artery trial (OAT) enrolled stable patients with persistently occluded IRAs beyond 24 hr and up to 28 days post-MI. Methods Myocardial blush was assessed using TIMI MPG grading in 261 patients with TIMI 3 epicardial flow following IRA PCI. Patients demonstrating impaired (0–1) versus preserved (2–3) MPG were compared with regard to baseline clinical and pre-PCI angiographic characteristics. Results Impaired MPG was observed in 60 of 261 patients (23%). By univariate analysis, impaired MPG was associated with failed fibrinolytic therapy, higher heart rate, lower systolic blood pressure, lower ejection fraction, LAD occlusion, absence of collaterals (P < 0.01) and ST elevation MI, lower diastolic blood pressure, and higher systolic sphericity index (P < 0.05). By multivariable analysis, higher heart rate, LAD occlusion, absence of collaterals and higher systolic sphericity index (P < 0.01), and lower systolic blood pressure (P < 0.05) were independently associated with impaired MPG. Conclusion Preserved microvascular integrity was present in a high proportion of patients following late recanalization of occluded IRAs post-MI. Presence of collaterals was independently associated with preserved MPG and likely accounted for the high frequency of preserved myocardial perfusion in this clinical setting. Impaired MPG was associated with baseline clinical and angiographic features consistent with larger infarct size. PMID:18798327

Patent ductus arteriosus closure using Occlutech® Duct Occluder, experience in Port Elizabeth, South Africa

PubMed Central

Pepeta, Lungile; Greyling, Adele; Nxele, Mahlubandile Fintan; Makrexeni, Zongezile Masonwabe

2017-01-01

Background: Percutaneous closure of patent ductus arteriosus (PDA) has become standard therapy. Experience with the Occlutech® Duct Occluder is limited. Methods: Data regarding ductal closure using Occlutech® Duct Occluder were reviewed and prospectively collected. Demographics, hemodynamic and angiographic characteristics, complications, and outcomes were documented. Results: From March 2013 to June 2016, 65 patients (43 females and 22 males) underwent percutaneous closure of the PDA using Occlutech® Duct Occluder. The median age of the patients was 11 months (range, 1–454 months) and the median weight was 8.5 kg (range 2.5–78 kg). The mean pulmonary artery median pressure was 27 mmHg (range, 12–100 mmHg) and the QP: Qs ratio median was 1.8 (range, 1–7.5), with a pulmonary vascular resistance mean of 2.7 WU (standard deviation [SD] ±2.1). Thirty-two patients had Krichenko Type A duct (49%); 7, Type C (11%); 4, Type D (6%); and 22, Type E (34%). The ductal size (narrowest diameter at the pulmonic end) mean was 3.5 mm (SD ± 1.9 mm). The screening time mean was 17.3 min (SD ± 11.6). Out of 63 patients with successful closure of the PDA using Occlutech® Duct Occluder, there were 15 patients with small PDAs; 25 with moderate PDAs, and 23 with large PDAs. In one patient, the device dislodged to the descending aorta, and in two patients, to the right pulmonary artery immediately following deployment, with successful percutaneous (two) and surgical (one) retrieval. Complete ductal occlusion was achieved in all 63 patients on day one. Conclusion: The Occlutech® Duct Occluder is a safe and effective device for closure of ducts in appropriately selected patients. PMID:28566820

Patent ductus arteriosus closure using Occlutech® Duct Occluder, experience in Port Elizabeth, South Africa.

PubMed

Pepeta, Lungile; Greyling, Adele; Nxele, Mahlubandile Fintan; Makrexeni, Zongezile Masonwabe

2017-01-01

Percutaneous closure of patent ductus arteriosus (PDA) has become standard therapy. Experience with the Occlutech® Duct Occluder is limited. Data regarding ductal closure using Occlutech® Duct Occluder were reviewed and prospectively collected. Demographics, hemodynamic and angiographic characteristics, complications, and outcomes were documented. From March 2013 to June 2016, 65 patients (43 females and 22 males) underwent percutaneous closure of the PDA using Occlutech® Duct Occluder. The median age of the patients was 11 months (range, 1-454 months) and the median weight was 8.5 kg (range 2.5-78 kg). The mean pulmonary artery median pressure was 27 mmHg (range, 12-100 mmHg) and the QP: Qs ratio median was 1.8 (range, 1-7.5), with a pulmonary vascular resistance mean of 2.7 WU (standard deviation [SD] ±2.1). Thirty-two patients had Krichenko Type A duct (49%); 7, Type C (11%); 4, Type D (6%); and 22, Type E (34%). The ductal size (narrowest diameter at the pulmonic end) mean was 3.5 mm (SD ± 1.9 mm). The screening time mean was 17.3 min (SD ± 11.6). Out of 63 patients with successful closure of the PDA using Occlutech® Duct Occluder, there were 15 patients with small PDAs; 25 with moderate PDAs, and 23 with large PDAs. In one patient, the device dislodged to the descending aorta, and in two patients, to the right pulmonary artery immediately following deployment, with successful percutaneous (two) and surgical (one) retrieval. Complete ductal occlusion was achieved in all 63 patients on day one. The Occlutech® Duct Occluder is a safe and effective device for closure of ducts in appropriately selected patients.

Recognition of partially occluded threat objects using the annealed Hopefield network

NASA Technical Reports Server (NTRS)

Kim, Jung H.; Yoon, Sung H.; Park, Eui H.; Ntuen, Celestine A.

1992-01-01

Recognition of partially occluded objects has been an important issue to airport security because occlusion causes significant problems in identifying and locating objects during baggage inspection. The neural network approach is suitable for the problems in the sense that the inherent parallelism of neural networks pursues many hypotheses in parallel resulting in high computation rates. Moreover, they provide a greater degree of robustness or fault tolerance than conventional computers. The annealed Hopfield network which is derived from the mean field annealing (MFA) has been developed to find global solutions of a nonlinear system. In the study, it has been proven that the system temperature of MFA is equivalent to the gain of the sigmoid function of a Hopfield network. In our early work, we developed the hybrid Hopfield network (HHN) for fast and reliable matching. However, HHN doesn't guarantee global solutions and yields false matching under heavily occluded conditions because HHN is dependent on initial states by its nature. In this paper, we present the annealed Hopfield network (AHN) for occluded object matching problems. In AHN, the mean field theory is applied to the hybird Hopfield network in order to improve computational complexity of the annealed Hopfield network and provide reliable matching under heavily occluded conditions. AHN is slower than HHN. However, AHN provides near global solutions without initial restrictions and provides less false matching than HHN. In conclusion, a new algorithm based upon a neural network approach was developed to demonstrate the feasibility of the automated inspection of threat objects from x-ray images. The robustness of the algorithm is proved by identifying occluded target objects with large tolerance of their features.

21 CFR 882.5150 - Intravascular occluding catheter.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Intravascular occluding catheter. 882.5150 Section 882.5150 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES NEUROLOGICAL DEVICES Neurological Therapeutic Devices § 882.5150 Intravascular...

21 CFR 882.5150 - Intravascular occluding catheter.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Intravascular occluding catheter. 882.5150 Section 882.5150 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES NEUROLOGICAL DEVICES Neurological Therapeutic Devices § 882.5150 Intravascular...

Vascular occlusion with a balloon-expandable stent occluder.

PubMed

Moss, J G; Laborde, J C; Clem, M C; Rivera, F J; Encarnacion, C E; Meyer, K B; Palmaz, J C

1994-05-01

To evaluate the effectiveness of a new vascular occlusion device. The device was created by coating a balloon-expandable stent with a silicone sleeve that tapers to a blind-ended nozzle at its leading end. Once crimp-mounted on an angioplasty balloon catheter, the device is introduced over a guide wire through a small end hole in the nozzle. The device was tested for stability and occlusive ability. No migration was measured over a pulsatile pulse range of 50-300 mm Hg, and mean flow rate in the occluded vessel was reduced from 443 mL/min +/- 99 (standard deviation) to 1.9 mL/min +/- 2.7. Subsequently, 12 arteries were occluded in three dogs, and immediate vascular occlusion was achieved in all vessels. An arteriovenous fistula was created in another six dogs and was successfully occluded with the device. Follow-up arteriography at 3 months demonstrated persistent occlusion with no migration of the device. This new occlusive device offers immediate vascular occlusion with excellent stability.

Modulation of occluding junctions alters the hematopoietic niche to trigger immune activation

PubMed Central

Khadilkar, Rohan J; Vogl, Wayne; Goodwin, Katharine

2017-01-01

Stem cells are regulated by signals from their microenvironment, or niche. During Drosophila hematopoiesis, a niche regulates prohemocytes to control hemocyte production. Immune challenges activate cell-signalling to initiate the cellular and innate immune response. Specifically, certain immune challenges stimulate the niche to produce signals that induce prohemocyte differentiation. However, the mechanisms that promote prohemocyte differentiation subsequent to immune challenges are poorly understood. Here we show that bacterial infection induces the cellular immune response by modulating occluding-junctions at the hematopoietic niche. Occluding-junctions form a permeability barrier that regulates the accessibility of prohemocytes to niche derived signals. The immune response triggered by infection causes barrier breakdown, altering the prohemocyte microenvironment to induce immune cell production. Moreover, genetically induced barrier ablation provides protection against infection by activating the immune response. Our results reveal a novel role for occluding-junctions in regulating niche-hematopoietic progenitor signalling and link this mechanism to immune cell production following infection. PMID:28841136

Activation of Parathyroid Hormone 2 Receptor Induces Decorin Expression and Promotes Wound Repair

PubMed Central

Sato, Emi; Zhang, Ling-juan; Dorschner, Robert A.; Adase, Christopher A.; Choudhury, Biswa P.; Gallo, Richard L.

2018-01-01

In this study, we report that TIP39, a parathyroid hormone ligand family member that was recently identified to be expressed in the skin, can induce decorin expression and enhance wound repair. Topical treatment of mice with TIP39 accelerated wound repair, whereas TIP39-deficient mice had delayed repair that was associated with formation of abnormal collagen bundles. To study the potential mechanism responsible for the action of TIP39 in the dermis, fibroblasts were cultured in three-dimensional collagen gels, a process that results in enhanced decorin expression unless activated to differentiate to adipocytes, whereupon these cells reduce expression of several proteoglycans, including decorin. Small interfering RNA-mediated silencing of parathyroid hormone 2 receptor (PTH2R), the receptor for TIP39, suppressed the expression of extracellular matrix-related genes, including decorin, collagens, fibronectin, and matrix metalloproteases. Skin wounds in TIP39−/− mice had decreased decorin expression, and addition of TIP39 to cultured fibroblasts induced decorin and increased phosphorylation and nuclear translocation of CREB. Fibroblasts differentiated to adipocytes and treated with TIP39 also showed increased decorin and production of chondroitin sulfate. Furthermore, the skin of PTH2R−/− mice showed abnormal extracellular matrix structure, decreased decorin expression, and skin hardness. Thus, the TIP39-PTH2R system appears to be a previously unrecognized mechanism for regulation of extracellular matrix formation and wound repair. PMID:28454729

A Model Rotor in Axial Flight

NASA Technical Reports Server (NTRS)

McAlister, K. W.; Huang, S. S.; Abrego, A. I.

2001-01-01

A model rotor was mounted horizontally in the settling chamber of a wind tunnel to obtain performance and wake structure data under low climb conditions. The immediate wake of the rotor was carefully surveyed using 3-component particle image velocimetry to define the velocity and vortical content of the flow, and used in a subsequent study to validate a theory for the separate determination of induced and profile drag. Measurements were obtained for two collective pitch angles intended to render a predominately induced drag state and another with a marked increase in profile drag. A majority of the azimuthally directed vorticity in the wake was found to be concentrated in the tip vortices. However, adjacent layers of inboard vorticity with opposite sense were clearly present. At low collective, the close proximity of the tip vortex from the previous blade caused the wake from the most recent blade passage to be distorted. The deficit velocity component that was directed along the azimuth of the rotor blade was never more that 15 percent of the rotor tip speed, and except for the region of the tip vortex, appeared to have totally disappeared form the wake left by the previous blade.

Daytime eyeshine contributes to pupil camouflage in a cryptobenthic marine fish.

PubMed

Santon, Matteo; Bitton, Pierre-Paul; Harant, Ulrike K; Michiels, Nico K

2018-05-09

Ocular reflectors enhance eye sensitivity in dim light, but can produce reflected eyeshine when illuminated. Some fish can occlude their reflectors during the day. The opposite is observed in cryptic sit-and-wait predators such as scorpionfish and toadfish, where reflectors are occluded at night and exposed during the day. This results in daytime eyeshine, proposed to enhance pupil camouflage by reducing the contrast between the otherwise dark pupil and the surrounding tissue. In this study, we test this hypothesis in the scorpionfish Scorpaena porcus and show that eyeshine is the result of two mechanisms: the previously described Stratum Argenteum Reflected (SAR) eyeshine, and Pigment Epithelium Transmitted (PET) eyeshine, a newly described mechanism for this species. We confirm that the ocular reflector is exposed only when the eye is light-adapted, and present field measurements to show that eyeshine reduces pupil contrast against the iris. We then estimate the relative contribution of SAR and PET eyeshine to pupil brightness. Visual models for different light scenarios in the field show that daytime eyeshine enhances pupil camouflage from the perspective of a prey fish. We propose that the reversed occlusion mechanism of some cryptobenthic predators has evolved as a compromise between camouflage and vision.

Serial dependence promotes object stability during occlusion

PubMed Central

Liberman, Alina; Zhang, Kathy; Whitney, David

2016-01-01

Object identities somehow appear stable and continuous over time despite eye movements, disruptions in visibility, and constantly changing visual input. Recent results have demonstrated that the perception of orientation, numerosity, and facial identity is systematically biased (i.e., pulled) toward visual input from the recent past. The spatial region over which current orientations or face identities are pulled by previous orientations or identities, respectively, is known as the continuity field, which is temporally tuned over the past several seconds (Fischer & Whitney, 2014). This perceptual pull could contribute to the visual stability of objects over short time periods, but does it also address how perceptual stability occurs during visual discontinuities? Here, we tested whether the continuity field helps maintain perceived object identity during occlusion. Specifically, we found that the perception of an oriented Gabor that emerged from behind an occluder was significantly pulled toward the random (and unrelated) orientation of the Gabor that was seen entering the occluder. Importantly, this serial dependence was stronger for predictable, continuously moving trajectories, compared to unpredictable ones or static displacements. This result suggests that our visual system takes advantage of expectations about a stable world, helping to maintain perceived object continuity despite interrupted visibility. PMID:28006066

Numerical procedure to determine geometric view factors for surfaces occluded by cylinders

NASA Technical Reports Server (NTRS)

Sawyer, P. L.

1978-01-01

A numerical procedure was developed to determine geometric view factors between connected infinite strips occluded by any number of infinite circular cylinders. The procedure requires a two-dimensional cross-sectional model of the configuration of interest. The two-dimensional model consists of a convex polygon enclosing any number of circles. Each side of the polygon represents one strip, and each circle represents a circular cylinder. A description and listing of a computer program based on this procedure are included in this report. The program calculates geometric view factors between individual strips and between individual strips and the collection of occluding cylinders.

[Percutaneous closure of ductus arteriosus and muscular ventricular defect with amplatzer occluder in a patient with severe pulmonary hypertension].

PubMed

García-Montes, José Antonio; Zabal Cerdeira, Carlos; Calderón-Colmenero, Juan; Espínola, Nilda; Fernández de la Reguera, Guillermo; Buendía Hernández, Alfonso

2005-01-01

Surgical treatment of multiple muscular ventricular septal defects with associated lesions and severe pulmonary hypertension has a high morbility and mortality. Closure of these defects by the Amplatzer muscular VSD occluder is an alternative to surgery, avoiding the need of cardiopulmonary bypass. We present the case of a 38 year-old woman with signs of heart failure in NYHA functional class IV, with two muscular ventricular septal defects, patent ductus arteriosus and severe pulmonary hypertension, that were treated with three Amplatzer muscular VSD occluders, with significant reduction of pulmonary pressure and functional class improvement.

Percutaneous Endovascular Salvage Techniques for Implanted Venous Access Device Dysfunction

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

Breault, Stéphane, E-mail: stephane.breault@chuv.ch; Glauser, Frédéric, E-mail: frederic.glauser@chuv.ch; Babaker, Malik, E-mail: malik.babaker@chuv.ch

2015-06-15

PurposeImplanted venous access devices (IVADs) are often used in patients who require long-term intravenous drug administration. The most common causes of device dysfunction include occlusion by fibrin sheath and/or catheter adherence to the vessel wall. We present percutaneous endovascular salvage techniques to restore function in occluded catheters. The aim of this study was to evaluate the feasibility, safety, and efficacy of these techniques.Methods and MaterialsThrough a femoral or brachial venous access, a snare is used to remove fibrin sheath around the IVAD catheter tip. If device dysfunction is caused by catheter adherences to the vessel wall, a new “mechanical adhesiolysis”more » maneuver was performed. IVAD salvage procedures performed between 2005 and 2013 were analyzed. Data included clinical background, catheter tip position, success rate, recurrence, and rate of complication.ResultsEighty-eight salvage procedures were performed in 80 patients, mostly women (52.5 %), with a mean age of 54 years. Only a minority (17.5 %) of evaluated catheters were located at an optimal position (i.e., cavoatrial junction ±1 cm). Mechanical adhesiolysis or other additional maneuvers were used in 21 cases (24 %). Overall technical success rate was 93.2 %. Malposition and/or vessel wall adherences were the main cause of technical failure. No complications were noted.ConclusionThese IVAD salvage techniques are safe and efficient. When a catheter is adherent to the vessel wall, mechanical adhesiolysis maneuvers allow catheter mobilization and a greater success rate with no additional risk. In patients who still require long-term use of their IVAD, these procedures can be performed safely to avoid catheter replacement.« less

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

Wang Wansheng; Dong Yonghua, E-mail: dongyhua@yahoo.com; Liu Bin

The objective of this study was to evaluate the feasibility and safety of lung volume reduction by transbronchial alcohol and lipiodol suspension infusion with the aid of balloon-tipped catheter occlusion. Twenty-six healthy adult rabbits were divided into four treatment groups: alcohol and lipiodol suspension infusion (n = 8), lipiodol infusion (n = 8), alcohol infusion (n = 5), or bronchial lumen occlusion (n = 5). After selective lobar or segmental bronchial catheterization using a balloon-tipped occlusion catheter, the corresponding drug infusion was performed. Bone cement was used to occlude the bronchial lumen in the occlusion group. The animals were followedmore » up for 10 weeks by chest X-ray and computed tomography (CT), and then the whole lungs were harvested for histological examination. Alcohol and lipiodol suspension or lipiodol could be stably retained in alveoli in the first two groups based on chest X-ray and CT, but obvious collapse only occurred in the group receiving alcohol and lipiodol suspension or the bronchial lumen occlusion group. Histological examination revealed damage and disruption of the alveolar epithelium and fibrosis in related lung tissue in the group receiving alcohol and lipiodol suspension. Similar changes were seen in the bronchial lumen occlusion group, apart from obvious marginal emphysema of the target areas in two animals. Interstitial pneumonia and dilated alveoli existed in some tissue in target areas in the lipiodol group, in which pulmonary fibrosis obliterating alveoli also occurred. Chronic alveolitis and pleural adhesion in target areas occurred in the group infused with alcohol alone, whereas visceral pleura of the other three groups was regular and no pleural effusion or adhesion was found. Alcohol and lipiodol suspension that is stably retained in alveoli can result in significant lung volume reduction. Through alcohol and lipiodol suspension infusion, obstructive emphysema or pneumonia arising from bronchial lumen occlusion could be avoided.« less

Extensive scarring induced by chronic intrathecal tubing augmented cord tissue damage and worsened functional recovery after rat spinal cord injury.

PubMed

Zhang, Shu-xin; Huang, Fengfa; Gates, Mary; White, Jason; Holmberg, Eric G

2010-08-30

Intrathecal infusion has been widely used to directly deliver drugs or neurotrophins to a lesion site following spinal cord injury. Evidence shows that intrathecal infusion is efficient for 7 days but is markedly reduced after 14 days, due to time dependent occlusion. In addition, extensive fibrotic scarring is commonly observed with intrathecal infusion. These anomalies need to be clearly elucidated in histology. In the present study, all adult Long-Evans rats received a 25 mm contusion injury on spinal cord T10 produced using the NYU impactor device. Immediately after injury, catheter tubing with an outer diameter of 0.38 mm was inserted through a small dural opening at L3 into the subdural space with the tubing tip positioned near the injury site. The tubing was connected to an Alzet mini pump, which was filled with saline solution and was placed subcutaneously. Injured rats without tubing served as control. Rats were behaviorally tested for 6 weeks using the BBB locomotor rating scale and histologically assessed for tissue scarring. Six weeks later, we found that the intrathecal tubing caused extensive scarring and inflammation, related to neutrophils, macrophages and plasma cells. The tubing's tip was occluded by scar tissue and inflammatory cells. The scar tissue surrounding the tubing consists of 20-70 layers of fibroblasts and densely compacted collagen fibers, seriously compressing and damaging the cord tissue. BBB scores of rats with intrathecal tubing were significantly lower than control rats (p<0.01) from 2 weeks after injury, implying serious impairment of functional recovery caused by the scarring. Copyright (c) 2010 Elsevier B.V. All rights reserved.

Structural locus of transmucosal albumin efflux in canine ileum. A fluorescent study.

PubMed

Granger, D N; Cook, B H; Taylor, A E

1976-12-01

This study demonstrates the effects of elevated intestinal venous pressure on the intestinal tissue spaces and the histological locus of the transmucosal albumin flux under such conditions. The authors were able to localize albumin in the tissues using an Evans blue-albumin fluorescence technique. This technique makes use of the fluorescence properties and albumin affinity of Evans blue dye (T-1824). Evans blue dye has a high affinity for albumin and emits a red-orange fluorescence at a wavelength of 720 nm. Evans blue was mixed with a solution of bovine serum albumin at concentrations that yield negligible amounts of free dye. Control ileal samples were obtained in order to visualize the natural tissue morphology and fluorescence. The Evans blue-albumin solution was injected and tissue samples were obtained 15 and 60 min postinjection, then venous outflow was occluded and after 15 and 60 min the tissues were sampled. Each sample was immediately frozen, freeze dried, embedded in paraffin, and 7-mu sections were made. The Evans blue-albumin was demonstrated histologically with a fluorescence microscope. No leakage sites were apparent at normal venous pressures. However, after elevation of venous pressure, Evans blue-albumin was observed in the interepithelial and/or intraepithelial spaces of villus tips, but no Evans blue-albumin was observed either between or within the epithelial cells of the crypts, or within the tubular crypt lumina. These results indicate that at elevated venous pressures, the transmucosal albumin flux occurs exclusively at the villus tip region, suggesting a great vulnerability of the cells found in this region to elevations in tissue pressure as compared to the crypt epithelial cells.

Creep, Fatigue and Environmental Interactions and Their Effect on Crack Growth in Superalloys

NASA Technical Reports Server (NTRS)

Telesman, J.; Gabb, T. P.; Ghosn, L. J.; Smith, T.

2017-01-01

Complex interactions of creep/fatigue/environment control dwell fatigue crack growth (DFCG) in superalloys. Crack tip stress relaxation during dwells significantly changes the crack driving force and influence DFCG. Linear Elastic Fracture Mechanics, Kmax, parameter unsuitable for correlating DFCG behavior due to extensive visco-plastic deformation. Magnitude of remaining crack tip axial stresses controls DFCG resistance due to the brittle-intergranular nature of the crack growth process. Proposed a new empirical parameter, Ksrf, which incorporates visco-plastic evolution of the magnitude of remaining crack tip stresses. Previous work performed at 704C, extend the work to 760C.

Thulium fiber laser lithotripsy using a muzzle brake fiber tip

NASA Astrophysics Data System (ADS)

Hutchens, Thomas C.; Gonzalez, David A.; Irby, Pierce B.; Fried, Nathaniel M.

2017-02-01

The Thulium fiber laser (TFL) is being explored as an alternative to Holmium:YAG laser for lithotripsy. TFL beam profile allows coupling of higher power into smaller fibers than multimode Holmium laser beam, without proximal fiber tip degradation. A smaller fiber provides more space in ureteroscope working channel for increased saline irrigation and allows maximum ureteroscope flexion. However, distal fiber tip burnback increases as fiber diameter decreases. Previous studies utilizing hollow steel sheaths around recessed distal fiber tips reduced fiber burnback, but increased retropulsion. In this study, a "fiber muzzle brake" was tested for reducing fiber burnback and stone retropulsion. TFL lithotripsy studies were performed at 1908 nm, 35 mJ, 500 μs, and 300 Hz using a 100-μm-core fiber. The optimal stainless steel muzzle brake tip tested consisted of a 1-cm-long, 560-μm-OD, 360-μm-ID tube with 275-μm thru hole located 250-μm from the distal end. The fiber tip was recessed a distance of 500 μm. Stone phantom retropulsion, fiber tip burnback, and calcium oxalate stone ablation studies were performed, ex vivo. Small stones with a mass of 40 +/- 4 mg and 4-mm-diameter were ablated over a 1.5-mm sieve in 25 +/- 4 s (n=10), without distal fiber tip burnback. Reduction in stone phantom retropulsion distance by 50% and 85% was observed when using muzzle brake tips versus 100-μm-core bare fibers and hollow steel tip fibers. The muzzle brake fiber tip provided efficient stone ablation, reduced stone retropulsion, and minimal fiber degradation during TFL lithotripsy.

Enhanced Actuator Line Simulation of a Wind Turbine by including the Conservative Load at the Blade Tip

NASA Astrophysics Data System (ADS)

Herraez, Ivan; Micallef, Daniel; van Kuik, Gijs A. M.; Peinke, Joachim

2015-11-01

At the tip of wind turbine blades, the radial bound circulation is transformed into chordwise circulation just before being released as trailing vorticity, giving rise to the tip vortex. The force acting on the chordwise circulation contains a radial and a normal component with respect to the blade axis. This load does not contribute to the torque, so it is a conservative load. Due to this, it is disregarded in the engineering tools used for the design of wind turbines. However, as we demonstrated in a previous work, the conservative load might influence the trajectory of the tip vortex. In order to see how this affects the blade loads, in this research we perform large eddy simulations with an actuator line model where the conservative load has been included. The conservative load reduces the angle of attack in the tip region as a consequence of the modified tip vortex trajectory. This has a negative influence on the lift and the power output. We conclude that the accuracy of engineering design tools of wind turbines can be improved if the conservative load acting at the tip is considered.

Applying Emmert’s Law to the Poggendorff illusion

PubMed Central

Talasli, Umur; Inan, Asli Bahar

2015-01-01

The Poggendorff illusion was approached with a novel perspective, that of applying Emmert’s Law to the situation. The extensities between the verticals and the transversals happen to be absolutely equal in retinal image size, whereas the registered distance for the verticals must be smaller than that of the transversals due to the fact that the former is assumed to occlude the latter. This combination of facts calls for the operation of Emmert’s Law, which results in the shrinkage of the occluding space between the verticals. Since the retinal image shows the transversals to be in contact with the verticals, the shrinkage must drag the transversals inwards in the cortical representation in order to eliminate the gaps. Such dragging of the transversals produces the illusory misalignment, which is a dictation of geometry. Some of the consequences of this new explanation were tested in four different experiments. In Experiment 1, a new illusion, the tilting of an occluded continuation of an oblique line, was predicted and achieved. In Experiments 2 and 3, perceived nearness of the occluding entity was manipulated via texture density variations and the predicted misalignment variations were confirmed by using a between-subjects and within-subjects designs, respectively. In Experiment 4, tilting of the occluded segment of the transversal was found to vary in the predicted direction as a result of being accompanied by the same texture cues used in Experiments 2 and 3. PMID:26528162

18 CFR 270.302 - Occluded natural gas produced from coal seams.

Code of Federal Regulations, 2014 CFR

2014-04-01

... produced from coal seams. 270.302 Section 270.302 Conservation of Power and Water Resources FEDERAL ENERGY... produced from coal seams. A person seeking a determination that natural gas is occluded natural gas produced from coal seams must file an application with the jurisdictional agency which contains the...

18 CFR 270.302 - Occluded natural gas produced from coal seams.

Code of Federal Regulations, 2012 CFR

2012-04-01

... produced from coal seams. 270.302 Section 270.302 Conservation of Power and Water Resources FEDERAL ENERGY... produced from coal seams. A person seeking a determination that natural gas is occluded natural gas produced from coal seams must file an application with the jurisdictional agency which contains the...

18 CFR 270.302 - Occluded natural gas produced from coal seams.

Code of Federal Regulations, 2010 CFR

2010-04-01

... produced from coal seams. 270.302 Section 270.302 Conservation of Power and Water Resources FEDERAL ENERGY... produced from coal seams. A person seeking a determination that natural gas is occluded natural gas produced from coal seams must file an application with the jurisdictional agency which contains the...

18 CFR 270.302 - Occluded natural gas produced from coal seams.

Code of Federal Regulations, 2011 CFR

2011-04-01

... produced from coal seams. 270.302 Section 270.302 Conservation of Power and Water Resources FEDERAL ENERGY... produced from coal seams. A person seeking a determination that natural gas is occluded natural gas produced from coal seams must file an application with the jurisdictional agency which contains the...

18 CFR 270.302 - Occluded natural gas produced from coal seams.

Code of Federal Regulations, 2013 CFR

2013-04-01

... produced from coal seams. 270.302 Section 270.302 Conservation of Power and Water Resources FEDERAL ENERGY... produced from coal seams. A person seeking a determination that natural gas is occluded natural gas produced from coal seams must file an application with the jurisdictional agency which contains the...

Contour Entropy: A New Determinant of Perceiving Ground or a Hole

ERIC Educational Resources Information Center

Gillam, Barbara J.; Grove, Philip M.

2011-01-01

Figure-ground perception is typically described as seeing one surface occluding another. Figure properties, not ground properties, are considered the significant factors. In scenes, however, a near surface will often occlude multiple contours and surfaces, often at different depths, producing alignments that are improbable except under conditions…

Hidden in Plain Sight: Occlusion in Pedagogical Genres

ERIC Educational Resources Information Center

Neaderhiser, Stephen E.

2016-01-01

Occluded genres in academia work "behind the scenes" to support and develop an academic's professional identity. However, while significant attention has been paid to occluded genres that support an academic's identity as a researcher, very little scholarship examines how occlusion operates in genres of pedagogy, such as the syllabus,…

Balloon-Occluded Percutaneous Transhepatic Obliteration of Isolated Vesical Varices Causing Gross Hematuria

PubMed Central

Lim, Dong Hoon; Kim, Min Seok; Kim, Chul Sung

2013-01-01

Gross hematuria secondary to vesical varices is an unusual presentation. We report such a case recurrent gross hematuria in a male patient who had a history of bladder substitution with ileal segments that had been treated by balloon-occluded percutaneous transhepatic obliteration of vesical varices. PMID:23323037

Tip Vortex and Wake Characteristics of a Counterrotating Open Rotor

NASA Technical Reports Server (NTRS)

VanZante, Dale E.; Wernet, Mark P.

2012-01-01

One of the primary noise sources for Open Rotor systems is the interaction of the forward rotor tip vortex and blade wake with the aft rotor. NASA has collaborated with General Electric on the testing of a new generation of low noise, counterrotating Open Rotor systems. Three-dimensional particle image velocimetry measurements were acquired in the intra-rotor gap of the Historical Baseline blade set. The velocity measurements are of sufficient resolution to characterize the tip vortex size and trajectory as well as the rotor wake decay and turbulence character. The tip clearance vortex trajectory is compared to results from previously developed models. Forward rotor wake velocity profiles are shown. Results are presented in a form as to assist numerical modeling of Open Rotor system aerodynamics and acoustics.

Method and apparatus for the guided ablative therapy of fast ventricular arrhythmia

NASA Technical Reports Server (NTRS)

Cohen, Richard J. (Inventor); Barley, Maya (Inventor)

2010-01-01

Method and apparatus for guiding ablative therapy of abnormal biological electrical excitation. The excitation from the previous excitatory wave is significant at the beginning of the next excitation. In particular, it is designed for treatment of fast cardiac arrhythmias. Electrical signals are acquired from recording electrodes, and an inverse dipole method is used to identify the site of origin of an arrhythmia. The location of the tip of an ablation catheter is similarly localized from signals acquired from the recording electrodes while electrical pacing energy is delivered to the tip of the catheter close to or in contact with the cardiac tissue. The catheter tip is then guided to the site of origin of the arrhythmia, and ablative radio frequency energy is delivered to its tip to ablate the site.

Gonioscopy-assisted Transluminal Trabeculotomy (GATT): Thermal Suture Modification With a Dye-stained Rounded Tip.

PubMed

Grover, Davinder S; Fellman, Ronald L

2016-06-01

To describe a novel technique for thermally marking the tip of a suture, in preparation for a gonioscopy-assisted transluminal trabeculotomy. One patient was used as an example for this technique. Technique report. The authors introduce a modification of a novel surgical procedure (GATT) in which a suture is marked and thermally blunted allowing a proper visualization while performing an ab interno, minimally invasive, circumferential 360-degree suture trabeculotomy. The authors have previously reported on the GATT surgery with the use of an illuminated microcatheter, which allowed for visualization of the tip of the catheter as it circumnavigated Schlemm canal. This modification allows for similar visualization of the tip of the suture, however, is much more cost-effective while still maintaining similar safety.

Numerical analysis of turbine blade tip treatments

NASA Technical Reports Server (NTRS)

Gopalaswamy, Nath S.; Whitaker, Kevin W.

1992-01-01

Three-dimensional solutions of the Navier-Stokes equations for a turbine blade with a turning angle of 180 degrees have been computed, including blade tip treatments involving cavities. The geometry approximates a preliminary design for the GGOT (Generic Gas Oxidizer Turbine). The data presented here will be compared with experimental data to be obtained from a linear cascade using original GGOT blades. Results have been computed for a blade with 1 percent clearance, based on chord, and three different cavity sizes. All tests were conducted at a Reynolds number of 4 x 10 exp 7. The grid contains 39,440 points with 10 spanwise planes in the tip clearance region of 5.008E-04 m. Streamline plots and velocity vectors together with velocity divergence plots reveal the general flow behavior in the clearance region. Blade tip temperature calculations suggest placement of a cavity close to the upstream side of the blade tip for reduction of overall blade tip temperature. The solutions do not account for the relative motion between the endwall and the turbine blade. The solutions obtained are generally consistent with previous work done in this area,

Study and Sub-System Optimization of Propulsion and Drive Systems for the Large Civil TiltRotor (LCTR2) Rotorcraft

NASA Technical Reports Server (NTRS)

Robuck, Mark; Wilkerson, Joseph; Snyder, Christopher A.; Zhang, Yiyi; Maciolek, Bob

2013-01-01

In a series of study tasks conducted as a part of NASA's Fundamental Aeronautics Program, Rotary Wing Project, Boeing and Rolls-Royce explored propulsion, drive, and rotor system options for the NASA Large Civil Tilt Rotor (LCTR2) concept vehicle. The original objective of this study was to identify engine and drive system configurations to reduce rotor tip speed during cruise conditions and quantify the associated benefits. Previous NASA studies concluded that reducing rotor speed (from 650 fps hover tip speed) during cruise would reduce vehicle gross weight and fuel burn. Initially, rotor cruise speed ratios of 54% of the hover tip speed were of most interest during operation at cruise air speed of 310 ktas. Interim results were previously reported1 for cruise tip speed ratios of 100%, 77%, and 54% of the hover tip speed using engine and/or gearbox features to achieve the reduction. Technology levels from commercial off-the-shelf (COTS), through entry-in-service (EIS) dates of 2025 and 2035 were considered to assess the benefits of advanced technology on vehicle gross weight and fuel burn. This technical paper presents the final study results in terms of vehicle sizing and fuel burn as well as Operational and Support (O&S) costs. New vehicle sizing at rotor tip speed reduced to 65% of hover is presented for engine performance with an EIS 2035 fixed geometry variable speed power turbine. LCTR2 is also evaluated for missions range cases of 400, 600, 800, 1000, and 1200 nautical miles and cruise air speeds of 310, 350 and 375 ktas.

Investigation of tip clearance flow physics in axial flow turbine rotors

NASA Astrophysics Data System (ADS)

Xiao, Xinwen

In axial turbines, the tip clearance between casing wall and rotating blades results in a tip leakage flow, which significantly affects loss production, heat protection, vibration and noise. It is important to minimize these effects for a better turbine engine performance and higher reliability. Most of previous efforts were concentrated on turbine cascades that however may not completely and correctly simulate the flow physics in practical turbine rotors. An investigation has to be performed in turbine rotors to reveal the real tip leakage flow physics in order to provide a scientific basis for minimizing its effects. This is the objective of this thesis research. The three dimensional flow field near the end wall/tip clearance region in a turbine rotor has been investigated experimentally, complemented by a numerical simulation to study the influences of inlet turbulence intensities on the development of the tip leakage flow. The experimental investigation is carried out in a modern unshrouded high pressure turbine stage. The survey region covers 20% span near the end wall, and extends axially from 10% chord upstream of the leading edge, through the rotor passage, and to 20% chord downstream of the trailing edge. It has been found that the tip leakage effects extend only to the surveyed region. The three dimensional LDV technique is used to measure the velocity and turbulence field upstream of the rotor, inside the rotor passage, and near the trailing edge. The static pressure on blade surfaces is surveyed from the rotating frame. The transient pressure on the casing wall is measured using a dynamic pressure sensor with a shaft encoder. A rotating Five Hole Probe is employed to measure the losses as well as the pressure and the three dimensional velocity field at 20% chord downstream of the rotor. The unsteady flow field is also investigated at this location by using a slanted single-element Hot Wire technique. The physics of the tip leakage flow and vortex in turbine rotors, including its inception location, development, interaction with the main stream and the passage vortex, and decay, are revealed. The rotation effects on the boundary layer flow and the turbulence structure are discussed. The effects of the relative motion between the blade and the casing wall on the flow field near the tip clearance region are also investigated. The structure of the rotor wake, the nozzle wake, and their interaction are interpreted based on the instantaneous Hot Wire data. The numerical simulation on the influence of the inlet turbulence intensity on the development of the tip leakage flow is based on previous efforts. The results indicate that the tip leakage vortex diffuses very quickly under a high inlet turbulence intensity, resulting in a very weak tip leakage vortex and less losses.

Amodal completion of moving objects by pigeons.

PubMed

Nagasaka, Yasuo; Wasserman, Edward A

2008-01-01

In a series of four experiments, we explored whether pigeons complete partially occluded moving shapes. Four pigeons were trained to discriminate between a complete moving shape and an incomplete moving shape in a two-alternative forced-choice task. In testing, the birds were presented with a partially occluded moving shape. In experiment 1, none of the pigeons appeared to complete the testing stimulus; instead, they appeared to perceive the testing stimulus as incomplete fragments. However, in experiments 2, 3, and 4, three of the birds appeared to complete the partially occluded moving shapes. These rare positive results suggest that motion may facilitate amodal completion by pigeons, perhaps by enhancing the figure - ground segregation process.

Expression profiles of aquaporin homologues and petal movement during petal development in Tulipa gesneriana.

PubMed

Azad, Abul Kalam; Hanawa, Ryosuke; Ishikawa, Takahiro; Sawa, Yoshihiro; Shibata, Hitoshi

2013-07-01

Previously, we have characterized two tonoplast intrinsic proteins (TIPs) and four plasma membrane intrinsic proteins (PIPs) from the 2-day-old petals of tulip (Tulipa gesneriana). In this study, we analyzed the development of tulip petals and stems, temperature-dependent petal movement, the amount of ³H₂O transported into petals and stems during petal movement, and the transcript levels of two TIP (TgTIP1;1 and TgTIP1;2) and four TgPIP genes in petals and stems, from the first day of petal opening to day 12. The development of the petals and stems was completed by days 6 and 9, respectively, after the first day of petal opening. Temperature-dependent petal movement and the amount of ³H₂O that was transported into petals could be detected at significant levels up to day 6 with petal movement reaching a peak at day 3. Real-time reverse transcription-polymerase chain reaction analysis revealed that TgTIP1;1 and TgTIP1;2 were expressed ubiquitously in petals, stems, leaves, bulbs and roots. However, the expression level of TgTIP1;2 was very low in bulbs. The expression of both TgTIP1 genes was upregulated in close association with the development of petals but not with that of the stem. The four TgPIP genes were expressed at almost the same level during the development of the petals and the stem. However, the levels of the TgTIP1 and TgPIP transcripts in petals decreased during the course of petal wilting from day 9 onwards. These results suggest that TgTIP1;1 and TgTIP1;2 may contribute to petal development. Copyright © Physiologia Plantarum 2012.

Developments in Young Infants' Reasoning about Occluded Objects

ERIC Educational Resources Information Center

Aguiar, Andrea; Baillargeon, Renee

2002-01-01

Eight experiments were conducted to examine 3- and 3.5-month-old infants' responses to occlusion events. The results revealed two developments, one in infants' knowledge of when objects should and should not be occluded and the other in infants' ability to posit additional objects to make sense of events that would otherwise violate their…

Quiet eye facilitates sensorimotor preprograming and online control of precision aiming in golf putting.

PubMed

Causer, Joe; Hayes, Spencer J; Hooper, James M; Bennett, Simon J

2017-02-01

An occlusion protocol was used to elucidate the respective roles of preprograming and online control during the quiet eye period of golf putting. Twenty-one novice golfers completed golf putts to 6-ft and 11-ft targets under full vision or with vision occluded on initiation of the backswing. Radial error (RE) was higher, and quiet eye was longer, when putting to the 11-ft versus 6-ft target, and in the occluded versus full vision condition. Quiet eye durations, as well as preprograming, online and dwell durations, were longer in low-RE compared to high-RE trials. The preprograming component of quiet eye was significantly longer in the occluded vision condition, whereas the online and dwell components were significantly longer in the full vision condition. These findings demonstrate an increase in preprograming when vision is occluded. However, this was not sufficient to overcome the need for online visual control during the quiet eye period. These findings suggest the quiet eye period is composed of preprograming and online control elements; however, online visual control of action is critical to performance.

Cellular and dendritic growth in a binary melt - A marginal stability approach

NASA Technical Reports Server (NTRS)

Laxmanan, V.

1986-01-01

A simple model for the constrained growth of an array of cells or dendrites in a binary alloy in the presence of an imposed positive temperature gradient in the liquid is proposed, with the dendritic or cell tip radius calculated using the marginal stability criterion of Langer and Muller-Krumbhaar (1977). This approach, an approach adopting the ad hoc assumption of minimum undercooling at the cell or dendrite tip, and an approach based on the stability criterion of Trivedi (1980) all predict tip radii to within 30 percent of each other, and yield a simple relationship between the tip radius and the growth conditions. Good agreement is found between predictions and data obtained in a succinonitrile-acetone system, and under the present experimental conditions, the dendritic tip stability parameter value is found to be twice that obtained previously, possibly due to a transition in morphology from a cellular structure with just a few side branches, to a more fully developed dendritic structure.

Observations from varying the lift and drag inputs to a noise prediction method for supersonic helical tip speed propellers

NASA Technical Reports Server (NTRS)

Dittmar, J. H.

1984-01-01

Previous comparisons between calculated and measured supersonic helical tip speed propeller noise show them to have different trends of peak blade passing tone versus helical tip Mach number. It was postulated that improvements in this comparison could be made first by including the drag force terms in the prediction and then by reducing the blade lift terms at the tip to allow the drag forces to dominate the noise prediction. Propeller hub to tip lift distributions were varied, but they did not yield sufficient change in the predicted lift noise to improve the comparison. This result indicates that some basic changes in the theory may be needed. In addition, the noise predicted by the drag forces did not exhibit the same curve shape as the measured data. So even if the drag force terms were to dominate, the trends with helical tip Mach number for theory and experiment would still not be the same. The effect of the blade shock wave pressure rise was approxmated by increasing the drag coefficient at the blade tip. Predictions using this shock wdave approximation did have a curve shape similar to the measured data. This result indicates that the shock pressure rise probably controls the noise at supersonic tip speed and that the linear prediction method can give the proper noise trend with Mach number.

Quantitative assessment of intermolecular interactions by atomic force microscopy imaging using copper oxide tips

NASA Astrophysics Data System (ADS)

Mönig, Harry; Amirjalayer, Saeed; Timmer, Alexander; Hu, Zhixin; Liu, Lacheng; Díaz Arado, Oscar; Cnudde, Marvin; Strassert, Cristian Alejandro; Ji, Wei; Rohlfing, Michael; Fuchs, Harald

2018-05-01

Atomic force microscopy is an impressive tool with which to directly resolve the bonding structure of organic compounds1-5. The methodology usually involves chemical passivation of the probe-tip termination by attaching single molecules or atoms such as CO or Xe (refs 1,6-9). However, these probe particles are only weakly connected to the metallic apex, which results in considerable dynamic deflection. This probe particle deflection leads to pronounced image distortions, systematic overestimation of bond lengths, and in some cases even spurious bond-like contrast features, thus inhibiting reliable data interpretation8-12. Recently, an alternative approach to tip passivation has been used in which slightly indenting a tip into oxidized copper substrates and subsequent contrast analysis allows for the verification of an oxygen-terminated Cu tip13-15. Here we show that, due to the covalently bound configuration of the terminal oxygen atom, this copper oxide tip (CuOx tip) has a high structural stability, allowing not only a quantitative determination of individual bond lengths and access to bond order effects, but also reliable intermolecular bond characterization. In particular, by removing the previous limitations of flexible probe particles, we are able to provide conclusive experimental evidence for an unusual intermolecular N-Au-N three-centre bond. Furthermore, we demonstrate that CuOx tips allow the characterization of the strength and configuration of individual hydrogen bonds within a molecular assembly.

A role for Mfb1p in region-specific anchorage of high-functioning mitochondria and lifespan in Saccharomyces cerevisiae

PubMed Central

Pernice, Wolfgang M.; Vevea, Jason D.; Pon, Liza A.

2016-01-01

Previous studies indicate that replicative lifespan in daughter cells of Sacchraromyces cerevisiae depends on the preferential inheritance of young, high-functioning mitochondria. We report here that mitochondria are functionally segregated even within single mother cells in S. cerevisiae. A high-functioning population of mitochondria accumulates at the tip of the mother cell distal to the bud. We find that the mitochondrial F-box protein (Mfb1p) localizes to mitochondria in the mother tip and is required for mitochondrial anchorage at that site, independent of the previously identified anchorage protein Num1p. Deletion of MFB1 results in loss of the mother-tip-localized mitochondrial population, defects in mitochondrial function and premature replicative ageing. Inhibiting mitochondrial inheritance to buds, by deletion of MMR1, in mfb1Δ cells restores mitochondrial distribution, promotes mitochondrial function and extends replicative lifespan. Our results identify a mechanism that retains a reservoir of high-functioning mitochondria in mother cells and thereby preserves maternal reproductive capacity. PMID:26839174

The African Origin of Complex Projectile Technology: An Analysis Using Tip Cross-Sectional Area and Perimeter

PubMed Central

Sisk, Matthew L.; Shea, John J.

2011-01-01

Despite a body of literature focusing on the functionality of modern and stylistically distinct projectile points, comparatively little attention has been paid to quantifying the functionality of the early stages of projectile use. Previous work identified a simple ballistics measure, the Tip Cross-Sectional Area, as a way of determining if a given class of stone points could have served as effective projectile armatures. Here we use this in combination with an alternate measure, the Tip Cross-Sectional Perimeter, a more accurate proxy of the force needed to penetrate a target to a lethal depth. The current study discusses this measure and uses it to analyze a collection of measurements from African Middle Stone Age pointed stone artifacts. Several point types that were rejected in previous studies are statistically indistinguishable from ethnographic projectile points using this new measure. The ramifications of this finding for a Middle Stone Age origin of complex projectile technology is discussed. PMID:21755048

Facilitating higher-fidelity simulations of axial compressor instability and other turbomachinery flow conditions

NASA Astrophysics Data System (ADS)

Herrick, Gregory Paul

The quest to accurately capture flow phenomena with length-scales both short and long and to accurately represent complex flow phenomena within disparately sized geometry inspires a need for an efficient, high-fidelity, multi-block structured computational fluid dynamics (CFD) parallel computational scheme. This research presents and demonstrates a more efficient computational method by which to perform multi-block structured CFD parallel computational simulations, thus facilitating higher-fidelity solutions of complicated geometries (due to the inclusion of grids for "small'' flow areas which are often merely modeled) and their associated flows. This computational framework offers greater flexibility and user-control in allocating the resource balance between process count and wall-clock computation time. The principal modifications implemented in this revision consist of a "multiple grid block per processing core'' software infrastructure and an analytic computation of viscous flux Jacobians. The development of this scheme is largely motivated by the desire to simulate axial compressor stall inception with more complete gridding of the flow passages (including rotor tip clearance regions) than has been previously done while maintaining high computational efficiency (i.e., minimal consumption of computational resources), and thus this paradigm shall be demonstrated with an examination of instability in a transonic axial compressor. However, the paradigm presented herein facilitates CFD simulation of myriad previously impractical geometries and flows and is not limited to detailed analyses of axial compressor flows. While the simulations presented herein were technically possible under the previous structure of the subject software, they were much less computationally efficient and thus not pragmatically feasible; the previous research using this software to perform three-dimensional, full-annulus, time-accurate, unsteady, full-stage (with sliding-interface) simulations of rotating stall inception in axial compressors utilized tip clearance periodic models, while the scheme here is demonstrated by a simulation of axial compressor stall inception utilizing gridded rotor tip clearance regions. As will be discussed, much previous research---experimental, theoretical, and computational---has suggested that understanding clearance flow behavior is critical to understanding stall inception, and previous computational research efforts which have used tip clearance models have begged the question, "What about the clearance flows?''. This research begins to address that question.

The case of the missing visual details: Occlusion and long-term visual memory.

PubMed

Williams, Carrick C; Burkle, Kyle A

2017-10-01

To investigate the critical information in long-term visual memory representations of objects, we used occlusion to emphasize 1 type of information or another. By occluding 1 solid side of the object (e.g., top 50%) or by occluding 50% of the object with stripes (like a picket fence), we emphasized visible information about the object, processing the visible details in the former and the object's overall form in the latter. On a token discrimination test, surprisingly, memory for solid or stripe occluded objects at either encoding (Experiment 1) or test (Experiment 2) was the same. In contrast, when occluded objects matched at encoding and test (Experiment 3) or when the occlusion shifted, revealing the entire object piecemeal (Experiment 4), memory was better for solid compared with stripe occluded objects, indicating that objects are represented differently in long-term visual memory. Critically, we also found that when the task emphasized remembering exactly what was shown, memory performance in the more detailed solid occlusion condition exceeded that in the stripe condition (Experiment 5). However, when the task emphasized the whole object form, memory was better in the stripe condition (Experiment 6) than in the solid condition. We argue that long-term visual memory can represent objects flexibly, and task demands can interact with visual information, allowing the viewer to cope with changing real-world visual environments. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Modular femoral component for conversion of previous hip surgery in total hip arthroplasty.

PubMed

Goldstein, Wayne M; Branson, Jill J

2005-09-01

The conversion of previous hip surgery to total hip arthroplasty creates a durable construct that is anatomically accurate. Most femoral components with either cemented or cementless design have a fixed tapered proximal shape. The proximal femoral anatomy is changed due to previous hip surgery for fixation of an intertrochanteric hip fracture, proximal femoral osteotomy, or a fibular allograft for avascular necrosis. The modular S-ROM (DePuy Orthopaedics Inc., Warsaw, Ind) hip stem accommodates these issues and independently prepares the proximal and distal portion of the femur. In preparation and implantation, the S-ROM hip stem creates less hoop stresses on potentially fragile stress risers from screws and thin bone. The S-ROM hip stem also prepares a previously distorted anatomy by milling through cortical bone that can occlude the femoral medullar canals and recreate proper femoral anteversion and reduces the risk of intraoperative or postoperative periprosthetic fracture due to the flexible titanium-slotted stem. The S-ROM femoral stem is recommended for challenging total hip reconstructions.

Efficacy and safety of a single 2 mg dose or 4 mg double dose of alteplase for 50 occluded chest ports using a unique instillation technique.

PubMed

Sharma, Rajinder P; Ree, Chung Ja; Ree, Alexander

2008-01-01

To evaluate the effectiveness and safety of a single 2 mg dose or a 4 mg double dose of alteplase for restoring function in occluded chest ports. A prospective, open-label, nonblinded study was performed on 40 enrolled patients with a total of 50 chest ports at the Henry Ford Hospital Interventional Radiology Department (Detroid, Michigan, USA). Alteplase (Cathflo Activase; Genentech, USA), a recombinant tissue plasminogen activator produced by recombinant DNA technology, was used to restore the function of 50 occluded chest ports. Occlusion was defined as the inability to withdraw blood freely from the port, or the inability to flush the port easily. A 2 mg (2 mL) dose of alteplase was injected into the port through a Huber needle, using a gentle push and pull technique, and was left to dwell for 30 min. If the port remained occluded after the initial 2 mg alteplase treatment, an additional 2 mg alteplase treatment was administered with the same dwell time of 30 min. If a port had remained occluded despite the above regimen, this outcome would have been considered a failure and the chest port would have required surgical intervention. However, all ports were successfully treated, and no surgical intervention was required. The safety end points included minor or major hemorrhages, such as intracranial hemorrhages, or sepsis. Safety end points were determined by a 24 h follow-up telephone call. Of the 50 chest ports (30 single ports and 10 double ports) treated with alteplase, 36 required 2 mg (72%) and 14 required 4 mg (28%). The efficacy end point was 100% for all chest ports treated, without any adverse events. High efficacy and safety rates of restoring function in occluded chest ports were obtained with 2 mg or 4 mg doses of alteplase. Part of this high efficacy rate may be due to the gentle push and pull technique used in the present study.

Multi-cored vortices support function of slotted wing tips of birds in gliding and flapping flight

PubMed Central

2017-01-01

Slotted wing tips of birds are commonly considered an adaptation to improve soaring performance, despite their presence in species that neither soar nor glide. We used particle image velocimetry to measure the airflow around the slotted wing tip of a jackdaw (Corvus monedula) as well as in its wake during unrestrained flight in a wind tunnel. The separated primary feathers produce individual wakes, confirming a multi-slotted function, in both gliding and flapping flight. The resulting multi-cored wingtip vortex represents a spreading of vorticity, which has previously been suggested as indicative of increased aerodynamic efficiency. Considering benefits of the slotted wing tips that are specific to flapping flight combined with the wide phylogenetic occurrence of this configuration, we propose the hypothesis that slotted wings evolved initially to improve performance in powered flight. PMID:28539482

The Evolution of Transjugular Intrahepatic Portosystemic Shunt: Tips

PubMed Central

Fanelli, Fabrizio

2014-01-01

Since Richter's description in the literature in 1989 of the first procedure on human patients, transjugular intrahepatic portosystemic shunt (TIPS) has been worldwide considered as a noninvasive technique to manage portal hypertension complications. TIPS succeeds in lowering the hepatic sinusoidal pressure and in increasing the circulatory flow, thus reducing sodium retention, ascites recurrence, and variceal bleeding. Required several revisions of the shunt TIPS can be performed in case of different conditions such as hepatorenal syndrome, hepatichydrothorax, portal vein thrombosis, and Budd-Chiari syndrome. Most of the previous studies on TIPS procedure were based on the use of bare stents and most patients chose TIPS 2-3 years after traditional treatment, thus making TIPS appear to be not superior to endoscopy in survival rates. Bare stents were associated with higher incidence of shunt failure and consequently patients required several revisions during the follow-up. With the introduction of a dedicated e-PTFE covered stent-graft, these problems were completely solved, No more reinterventions are required with a tremendous improvement of patient's quality of life. One of the main drawbacks of the use of e-PTFE covered stent-graft is higher incidence of hepatic encephalopathy. In those cases refractory to the conventional medical therapy, a shunt reduction must be performed. PMID:27335841

Topology, divergence dates, and macroevolutionary inferences vary between different tip-dating approaches applied to fossil theropods (Dinosauria).

PubMed

Bapst, D W; Wright, A M; Matzke, N J; Lloyd, G T

2016-07-01

Dated phylogenies of fossil taxa allow palaeobiologists to estimate the timing of major divergences and placement of extinct lineages, and to test macroevolutionary hypotheses. Recently developed Bayesian 'tip-dating' methods simultaneously infer and date the branching relationships among fossil taxa, and infer putative ancestral relationships. Using a previously published dataset for extinct theropod dinosaurs, we contrast the dated relationships inferred by several tip-dating approaches and evaluate potential downstream effects on phylogenetic comparative methods. We also compare tip-dating analyses to maximum-parsimony trees time-scaled via alternative a posteriori approaches including via the probabilistic cal3 method. Among tip-dating analyses, we find opposing but strongly supported relationships, despite similarity in inferred ancestors. Overall, tip-dating methods infer divergence dates often millions (or tens of millions) of years older than the earliest stratigraphic appearance of that clade. Model-comparison analyses of the pattern of body-size evolution found that the support for evolutionary mode can vary across and between tree samples from cal3 and tip-dating approaches. These differences suggest that model and software choice in dating analyses can have a substantial impact on the dated phylogenies obtained and broader evolutionary inferences. © 2016 The Author(s).

Comparison of calculated and measured velocities near the tip of a model rotor blade at transonic speeds

NASA Technical Reports Server (NTRS)

Tauber, M. E.; Owen, F. K.; Langhi, R. G.; Palmer, G. E.

1985-01-01

The ability of the ROT22 code to predict accurately the transonic flow field in the crucial region around and beyond the tip of a high speed rotor blade was assessed. The computations were compared with extensive laser velocimetry measurements made at zero advance ratio and tip Mach numbers of 0.85, 0.88, 0.90, and 0.95. The comparison between theory and experiment was made using 300 scans for the three orthogonal velocity components covering a volume having a height of over one blade chord, a width of nearly two chords, and a length ranging from about 1 to 1.6 chords, depending on the tip speeds. The good agreement between the calculated and measured velocities established the ability of the code to predict the off blade flow field at high tip speeds. This supplements previous comparisons where surface pressures were shown to be well predicted on two different tips at advance ratios to 0.45, especially at the critical 90 deg azimuth blade position. These results demonstrate that the ROT22 code can be used with confidence to predict the important tip region flow field including the occurrence, strength, and location of shock waves causing high drag and noise.

Ear-body lift and a novel thrust generating mechanism revealed by the complex wake of brown long-eared bats (Plecotus auritus)

NASA Astrophysics Data System (ADS)

Johansson, L. Christoffer; Håkansson, Jonas; Jakobsen, Lasse; Hedenström, Anders

2016-04-01

Large ears enhance perception of echolocation and prey generated sounds in bats. However, external ears likely impair aerodynamic performance of bats compared to birds. But large ears may generate lift on their own, mitigating the negative effects. We studied flying brown long-eared bats, using high resolution, time resolved particle image velocimetry, to determine the aerodynamics of flying with large ears. We show that the ears and body generate lift at medium to cruising speeds (3-5 m/s), but at the cost of an interaction with the wing root vortices, likely reducing inner wing performance. We also propose that the bats use a novel wing pitch mechanism at the end of the upstroke generating thrust at low speeds, which should provide effective pitch and yaw control. In addition, the wing tip vortices show a distinct spiraling pattern. The tip vortex of the previous wingbeat remains into the next wingbeat and rotates together with a newly formed tip vortex. Several smaller vortices, related to changes in circulation around the wing also spiral the tip vortex. Our results thus show a new level of complexity in bat wakes and suggest large eared bats are less aerodynamically limited than previous wake studies have suggested.

The dynamics of secretion during sea urchin embryonic skeleton formation.

PubMed

Wilt, Fred H; Killian, Christopher E; Hamilton, Patricia; Croker, Lindsay

2008-05-01

Skeleton formation involves secretion of massive amounts of mineral precursor, usually a calcium salt, and matrix proteins, many of which are deposited on, or even occluded within, the mineral. The cell biological underpinnings of this secretion and subsequent assembly of the biomineralized skeletal element is not well understood. We ask here what is the relationship of the trafficking and secretion of the mineral and matrix within the primary mesenchyme cells of the sea urchin embryo, cells that deposit the endoskeletal spicule. Fluorescent labeling of intracellular calcium deposits show mineral precursors are present in granules visible by light microscopy, from whence they are deposited in the endoskeletal spicule, especially at its tip. In contrast, two different matrix proteins tagged with GFP are present in smaller post-Golgi vesicles only seen by electron microscopy, and the secreted protein are only incorporated into the spicule in the vicinity of the cell of origin. The matrix protein, SpSM30B, is post-translationally modified during secretion, and this processing continues after its incorporation into the spicule. Our findings also indicate that the mineral precursor and two well characterized matrix proteins are trafficked by different cellular routes.

The Dynamics of Secretion during Sea Urchin Embryonic Skeleton Formation

PubMed Central

Wilt, Fred H.; Killian, Christopher E.; Hamilton, Patricia; Croker, Lindsay

2008-01-01

Skeleton formation involves secretion of massive amounts of mineral precursor, usually a calcium salt, and matrix proteins, many of which are deposited on, or even occluded within, the mineral. The cell biological underpinnings of this secretion and subsequent assembly of the biomineralized skeletal element is not well understood. We ask here what is the relationship of the trafficking and secretion of the mineral and matrix within the primary mesenchyme cells of the sea urchin embryo, cells that deposit the endoskeletal spicule. Fluorescent labeling of intracellular calcium deposits show mineral precursors are present in granules visible by light microscopy, from whence they are deposited in the endoskeletal spicule, especially at its tip. In contrast, two different matrix proteins tagged with GFP are present in smaller post-Golgi vesicles only seen by electron microscopy, and the secreted protein are only incorporated into the spicule in the vicinity of the cell of origin. The matrix protein, SpSM30B, is post-translationally modified during secretion, and this processing continues after its incorporation into the spicule. Our findings also indicate that the mineral precursor and two well characterized matrix proteins are trafficked by different cellular routes. PMID:18355808

Voice Training and Therapy with a Semi-Occluded Vocal Tract: Rationale and Scientific Underpinnings

ERIC Educational Resources Information Center

Titze, Ingo R.

2006-01-01

Purpose: Voice therapy with a semi-occluded vocal tract has a long history. The use of lip trills, tongue trills, bilabial fricatives, humming, and phonation into tubes or straws has been hailed by clinicians, singing teachers, and voice coaches as efficacious for training and rehabilitation. Little has been done, however, to provide the…

Radiation-induced cerebrovascular disease in children

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

Wright, T.L.; Bresnan, M.J.

1976-06-01

Radiation-induced internal carotid artery occlusion has not been well recognized previously as a cause of childhood cerebrovascular disease. A child who had received radiation as a neonate for a hemangioma involving the left orbit at the age of 6 years experienced a recurrent right-sided paresis, vascular headaches, and speech difficulties. Angiography showed a hypoplastic left carotid artery with occlusion of both the anterior and middle cerebral arteries. Collateral vessels bypassed the occluded-stenotic segments. Review of the literature showed two additional cases of large vessel occlusion in childhood associated with anastomatic telangiectatic vessel development following early radiation therapy of facial hemangioma.

NMR Model of PrgI-SipD Interaction and its Implications in the Needle-Tip Assembly of the Salmonella Type III Secretion System

PubMed Central

Rathinavelan, Thenmalarchelvi; Lara-Tejero, Maria; Lefebre, Matthew; Chatterjee, Srirupa; McShan, Andrew C.; Guo, Da-Chuan; Tang, Chun; Galan, Jorge E.; De Guzman, Roberto N.

2014-01-01

Salmonella and other pathogenic bacteria use the type III secretion system (T3SS) to inject virulence proteins into human cells to initiate infections. The structural component of the T3SS contains a needle and a needle tip. The needle is assembled from PrgI needle protomers and the needle tip is capped with several copies of the SipD tip protein. How a tip protein docks on the needle is unclear. A crystal structure of a PrgI-SipD fusion protein docked on the PrgI needle results in steric clash of SipD at the needle tip when modeled on the recent atomic structure of the needle. Thus, there is currently no good model of how SipD is docked on the PrgI needle tip. Previously, we showed by NMR paramagnetic relaxation enhancement (PRE) methods that a specific region in the SipD coiled-coil is the binding site for PrgI. Others have hypothesized that a domain of the tip protein – the N-terminal α-helical hairpin, has to swing away during the assembly of the needle apparatus. Here, we show by PRE methods that a truncated form of SipD lacking the α-helical hairpin domain binds more tightly to PrgI. Further, PRE-based structure calculations revealed multiple PrgI binding sites on the SipD coiled-coil. Our PRE results together with the recent NMR-derived atomic structure of the Salmonella needle suggest a possible model of how SipD might dock at the PrgI needle tip. SipD and PrgI are conserved in other bacterial T3SSs, thus our results have wider implication in understanding other needle-tip complexes. PMID:24951833

Characterization of the TIP4P-Ew water model: vapor pressure and boiling point.

PubMed

Horn, Hans W; Swope, William C; Pitera, Jed W

2005-11-15

The liquid-vapor-phase equilibrium properties of the previously developed TIP4P-Ew water model have been studied using thermodynamic integration free-energy simulation techniques in the temperature range of 274-400 K. We stress that free-energy results from simulations need to be corrected in order to be compared to the experiment. This is due to the fact that the thermodynamic end states accessible through simulations correspond to fictitious substances (classical rigid liquids and classical rigid ideal gases) while experiments operate on real substances (liquids and real gases, with quantum effects). After applying analytical corrections the vapor pressure curve obtained from simulated free-energy changes is in excellent agreement with the experimental vapor pressure curve. The boiling point of TIP4P-Ew water under ambient pressure is found to be at 370.3+/-1.9 K, about 7 K higher than the boiling point of TIP4P water (363.7+/-5.1 K; from simulations that employ finite range treatment of electrostatic and Lennard-Jones interactions). This is in contrast to the approximately +15 K by which the temperature of the density maximum and the melting temperature of TIP4P-Ew are shifted relative to TIP4P, indicating that the temperature range over which the liquid phase of TIP4P-Ew is stable is narrower than that of TIP4P and resembles more that of real water. The quality of the vapor pressure results highlights the success of TIP4P-Ew in describing the energetic and entropic aspects of intermolecular interactions in liquid water.

Hydroxyl free radical production during torsional phacoemulsification.

PubMed

Aust, Steven D; Hebdon, Thomas; Humbert, Jordan; Dimalanta, Ramon

2010-12-01

To quantitate free radical generation during phacoemulsification using an ultrasonic phacoemulsification device that includes a torsional mode and evaluate tip designs specific to the torsional mode. Chemistry and Biochemistry Department, Utah State University, Logan, Utah, USA. Experimental study. Experiments were performed using the Infiniti Vision System and OZil handpiece. Hydroxyl radical concentrations in the aspirated irrigation solution during torsional phacoemulsification were quantitated as nanomolar malondialdehyde (nM MDA) and determined spectrophotometrically using the deoxyribose assay. The mean free radical production during phacoemulsification with torsional modality at 100% amplitude was 30.1 nM MDA ± 5.1 (SD) using a 0.9 mm 45-degree Kelman tapered ABS tip. With other tip designs intended for use with the torsional modality, free radical production was further reduced when fitted with the 0.9 mm 45-degree Kelman mini-flared ABS tip (13.2 ± 5.6 nM MDA) or the 0.9 mm 45-degree OZil-12 mini-flared ABS tip (14.3 ± 6.7 nM MDA). Although the measurements resulting from the use of the latter 2 tips were not statistically significantly different (P ≈ .25), they were different from those of the tapered tip (P<.0001). The MDA concentration in the aspirated irrigation solution using the torsional modality was approximately one half that reported for the handpiece's longitudinal modality in a previous study using the same bent-tip design (Kelman tapered, P<.0001). The level of MDA was further reduced approximately one half with torsional-specific tips. Copyright © 2010 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

A novel carbon tipped single micro-optrode for combined optogenetics and electrophysiology

PubMed Central

Vizvári, Attila D.; Bali, Zsolt K.; Márki, Balázs; Nagy, Lili V.; Kónya, Zoltán; Madarász, Dániel; Henn-Mike, Nóra; Varga, Csaba; Hernádi, István

2018-01-01

Optical microelectrodes (optrodes) are used in neuroscience to transmit light into the brain of a genetically modified animal to evoke and record electrical activity from light-sensitive neurons. Our novel micro-optrode solution integrates a light-transmitting 125 micrometer optical fiber and a 9 micrometer carbon monofilament to form an electrical lead element, which is contained in a borosilicate glass sheathing coaxial arrangement ending with a micrometer-sized carbon tip. This novel unit design is stiff and slender enough to be used for targeting deep brain areas, and may cause less tissue damage compared with previous models. The center-positioned carbon fiber is less prone to light-induced artifacts than side-lit metal microelectrodes previously presented. The carbon tip is capable of not only recording electrical signals of neuronal origin but can also provide valuable surface area for electron transfer, which is essential in electrochemical (voltammetry, amperometry) or microbiosensor applications. We present details of design and manufacture as well as operational examples of the newly developed single micro-optrode, which includes assessments of 1) carbon tip length–impedance relationship, 2) light transmission capabilities, 3) photoelectric artifacts in carbon fibers, 4) responses to dopamine using fast-scan cyclic voltammetry in vivo, and 5) optogenetic stimulation and spike or local field potential recording from the rat brain transfected with channelrhodopsin-2. With this work, we demonstrate that our novel carbon tipped single micro-optrode may open up new avenues for use in optogenetic stimulation when needing to be combined with extracellular recording, electrochemical, or microbiosensor measurements performed on a millisecond basis. PMID:29513711

Design of a noninvasive face mask for ocular occlusion in rats and assessment in a visual discrimination paradigm.

PubMed

Hager, Audrey M; Dringenberg, Hans C

2012-12-01

The rat visual system is structured such that the large (>90 %) majority of retinal ganglion axons reach the contralateral lateral geniculate nucleus (LGN) and visual cortex (V1). This anatomical design allows for the relatively selective activation of one cerebral hemisphere under monocular viewing conditions. Here, we describe the design of a harness and face mask allowing simple and noninvasive monocular occlusion in rats. The harness is constructed from synthetic fiber (shoelace-type material) and fits around the girth region and neck, allowing for easy adjustments to fit rats of various weights. The face mask consists of soft rubber material that is attached to the harness by Velcro strips. Eyeholes in the mask can be covered by additional Velcro patches to occlude either one or both eyes. Rats readily adapt to wearing the device, allowing behavioral testing under different types of viewing conditions. We show that rats successfully acquire a water-maze-based visual discrimination task under monocular viewing conditions. Following task acquisition, interocular transfer was assessed. Performance with the previously occluded, "untrained" eye was impaired, suggesting that training effects were partially confined to one cerebral hemisphere. The method described herein provides a simple and noninvasive means to restrict visual input for studies of visual processing and learning in various rodent species.

Prophylactic Hypogastric Artery Ballooning in a Patient with Complete Placenta Previa and Increta

PubMed Central

Yi, Kyong Wook; Seo, Tae-Seok; So, Kyeong A; Paek, Yu Chin; Kim, Hai-Joong

2010-01-01

Abnormal attachment of the placenta (Placenta accreta, increta, and percreta) is an uncommon but potentially lethal cause of maternal mortality from massive postpartum hemorrhage. A 33-yr-old woman, who had been diagnosed with a placenta previa, was referred at 30 weeks gestation. On ultrasound, a complete type of placenta previa and multiple intraplacental lacunae, suggestive of placenta accreta, were noted. For further evaluation of the placenta, pelvis MRI was performed and revealed findings suspicious of a placenta increta. An elective cesarean delivery and subsequent hysterectomy were planned for the patient at 38 weeks gestation. On the day of delivery, endovascular catheters for balloon occlusion were placed within the hypogastric arteries, prior to the cesarean section. In the operating room, immediately after the delivery of the baby, bilateral hypogastric arteries were occluded by inflation of the balloons in the catheters previously placed within. With the placenta retained within the uterus, a total hysterectomy was performed in the usual fashion. The occluding balloons were deflated after closure of the vaginal cuff with hemostasis. The patient had stable vital signs and normal laboratory findings during the recovery period; she was discharged six days after delivery without complications. The final pathology confirmed a placenta increta. PMID:20358016

Phase transitions in biogenic amorphous calcium carbonate

NASA Astrophysics Data System (ADS)

Gong, Yutao

Geological calcium carbonate exists in both crystalline phases and amorphous phases. Compared with crystalline calcium carbonate, such as calcite, aragonite and vaterite, the amorphous calcium carbonate (ACC) is unstable. Unlike geological calcium carbonate crystals, crystalline sea urchin spicules (99.9 wt % calcium carbonate and 0.1 wt % proteins) do not present facets. To explain this property, crystal formation via amorphous precursors was proposed in theory. And previous research reported experimental evidence of ACC on the surface of forming sea urchin spicules. By using X-ray absorption near-edge structure (XANES) spectroscopy and photoelectron emission microscopy (PEEM), we studied cross-sections of fresh sea urchin spicules at different stages (36h, 48h and 72h after fertilization) and observed the transition sequence of three mineral phases: hydrated ACC → dehydrated ACC → biogenic calcite. In addition, we unexpectedly found hydrated ACC nanoparticles that are surrounded by biogenic calcite. This observation indicates the dehydration from hydrated ACC to dehydrated ACC is inhibited, resulting in stabilization of hydrated ACC nanoparticles. We thought that the dehydration was inhibited by protein matrix components occluded within the biomineral, and we designed an in vitro assay to test the hypothesis. By utilizing XANES-PEEM, we found that SM50, the most abundant occluded matrix protein in sea urchin spicules, has the function to stabilize hydrated ACC in vitro.

Relationship between regional myocardial blood flow and thallium-201 distribution in the presence of coronary artery stenosis and dipyridamole-induced vasodilation.

PubMed Central

Mays, A E; Cobb, F R

1984-01-01

This study assesses the relationship between the distribution of thallium-201 and myocardial blood flow during coronary vasodilation induced by intravenous dipyridamole in canine models of partial and complete coronary artery stenosis. 10 dogs were chronically instrumented with catheters in the left atrium and aorta and with a balloon occluder and electromagnetic flow probe on the proximal left circumflex coronary artery. Regional myocardial blood flow was measured during control conditions with radioisotope-labeled microspheres, and the phasic reactive hyperemic response to a 20-s transient occlusion was then recorded. Dipyridamole was then infused intravenously until phasic coronary blood flow increased to match peak hyperemic values. The left circumflex coronary artery was either partially occluded to reduce phasic blood flow to control values (group 1) or it was completely occluded (group 2), and thallium-201 and a second microsphere label were injected. 5 min later, the animals were sacrificed, the left ventricle was sectioned into 1-2-g samples, and thallium-201 activity and regional myocardial blood flow were measured. Curvilinear regression analyses between thallium-201 localization and myocardial blood flow during dipyridamole infusion demonstrated a slightly better fit to a second- as compared with a first-order model, indicating a slight roll-off of thallium activity as myocardial blood flow increases. During the dipyridamole infusion, the increases in phasic blood flow, the distributions of regional myocardial blood flow, and the relationships between thallium-201 localization and regional blood flow were comparable to values previously observed in exercising dogs with similar occlusions. These data provide basic validation that supports the use of intravenous dipyridamole and thallium-201 as an alternative to exercise stress and thallium-201 for evaluating the effects of coronary occlusive lesions on the distribution of regional myocardial blood flow. PMID:6715540

A double-headed cathepsin B inhibitor devoid of warhead

PubMed Central

Schenker, Patricia; Alfarano, Pietro; Kolb, Peter; Caflisch, Amedeo; Baici, Antonio

2008-01-01

Most synthetic inhibitors of peptidases have been targeted to the active site for inhibiting catalysis through reversible competition with the substrate or by covalent modification of catalytic groups. Cathepsin B is unique among the cysteine peptidase for the presence of a flexible segment, known as the occluding loop, which can block the primed subsites of the substrate binding cleft. With the occluding loop in the open conformation cathepsin B acts as an endopeptidase, and it acts as an exopeptidase when the loop is closed. We have targeted the occluding loop of human cathepsin B at its surface, outside the catalytic center, using a high-throughput docking procedure. The aim was to identify inhibitors that would interact with the occluding loop thereby modulating enzyme activity without the help of chemical warheads against catalytic residues. From a large library of compounds, the in silico approach identified [2-[2-(2,4-dioxo-1,3-thiazolidin-3-yl)ethylamino]-2-oxoethyl] 2-(furan-2-carbonylamino) acetate, which fulfills the working hypothesis. This molecule possesses two distinct binding moieties and behaves as a reversible, double-headed competitive inhibitor of cathepsin B by excluding synthetic and protein substrates from the active center. The kinetic mechanism of inhibition suggests that the occluding loop is stabilized in its closed conformation, mainly by hydrogen bonds with the inhibitor, thus decreasing endoproteolytic activity of the enzyme. Furthermore, the dioxothiazolidine head of the compound sterically hinders binding of the C-terminal residue of substrates resulting in inhibition of the exopeptidase activity of cathepsin B in a physiopathologically relevant pH range. PMID:18796695

The role of transparency in da Vinci stereopsis.

PubMed

Zannoli, Marina; Mamassian, Pascal

2011-10-15

The majority of natural scenes contains zones that are visible to one eye only. Past studies have shown that these monocular regions can be seen at a precise depth even though there are no binocular disparities that uniquely constrain their locations in depth. In the so-called da Vinci stereopsis configuration, the monocular region is a vertical line placed next to a binocular rectangular occluder. The opacity of the occluder has been mentioned to be a necessary condition to obtain da Vinci stereopsis. However, this opacity constraint has never been empirically tested. In the present study, we tested whether da Vinci stereopsis and perceptual transparency can interact using a classical da Vinci configuration in which the opacity of the occluder varied. We used two different monocular objects: a line and a disk. We found no effect of the opacity of the occluder on the perceived depth of the monocular object. A careful analysis of the distribution of perceived depth revealed that the monocular object was perceived at a depth that increased with the distance between the object and the occluder. The analysis of the skewness of the distributions was not consistent with a double fusion explanation, favoring an implication of occlusion geometry in da Vinci stereopsis. A simple model that includes the geometry of the scene could account for the results. In summary, the mechanism responsible to locate monocular regions in depth is not sensitive to the material properties of objects, suggesting that da Vinci stereopsis is solved at relatively early stages of disparity processing. Copyright © 2011 Elsevier Ltd. All rights reserved.

Feasibility study on retinal vascular bypass surgery in isolated arterially perfused caprine eye model

PubMed Central

Chen, Y; Wu, W; Zhang, X; Fan, W; Shen, L

2011-01-01

Purpose To investigate the feasibility of bypassing occluded segments of retinal venous main vessels in isolated, arterially perfused caprine eyes via the closed-sky vitrectomy approach using keratoprosthesis. Methods Isolated caprine eyes were used in this study. For each eye, the retinal vessel was perfused by Krebs solution via ophthalmic artery, and pars plana vitrectomy was performed using temporary keratoprosthesis. All retinal micro-vascular maneuvers were performed in a closed-sky eyeball. The main retinal vein was blocked by endodiathermy at the site of the vessel's first branching. Two openings, several millimeters apart, were created by vascular punctures in both the main vein and its branch vein wall straddling the induced occluded segment. Catheterization was achieved using a flexible polyimide tube, with each end inserted into the vessel wall opening. A sealed connection between the vessel and the tube was obtained by endodiathermy. Bypass of the occluded retinal vein segment was thus achieved, and the patency of this vascular bypass was confirmed by intravascular staining. Results Puncturing, catheterization, and endodiathermy were viable by closed-sky approach using keratoprosthesis. Bypassing of the occluded retinal main vein segment was accomplished with the combination of these maneuvers. Good results were obtained in 23 of 38 (60%) caprine eyes. Conclusions This study demonstrated that bypassing the occluded segment of retinal main vein can be successfully performed in a closed-sky eyeball model of isolated, arterially perfused caprine eye. This early work indicated that the more advanced retinal vascular bypass surgery in in vivo eye may be feasible in the future. PMID:21921946

Results of the combined U.S. Multicenter Pivotal Study and the Continuing Access Study of the Nit-Occlud PDA device for percutaneous closure of patent ductus arteriosus.

PubMed

Moore, John W; Greene, Jessica; Palomares, Salvadore; Javois, Alexander; Owada, Carl Y; Cheatham, John P; Hoyer, Mark H; Jones, Thomas K; Levi, Daniel S

2014-12-01

This study aimed to compare the efficacy and safety of the Nit-Occlud PDA device (PFM Medical, Cologne, Germany) to benchmarks designed as objective performance criteria (OPC). The Nit-Occlud PDA is a nitinol coil-type patent ductus arteriosus (PDA) occluder with a reverse cone configuration, which is implanted using a controlled delivery system. Patients with <4-mm minimum diameter PDA were prospectively enrolled in the Pivotal and the Continuing Access Studies from 15 sites in the United States and were followed up for 12 months post-procedure. Investigator-reported outcomes were compared to OPC including a composite success criterion, efficacy criteria of successful closure (clinical and echocardiographic), and safety criteria incidence of adverse events (serious and of total). The Pivotal Study enrolled patients between November 1, 2002 and October 31, 2005, and the Continuing Access Study enrolled additional patients between September 1, 2006 and October 31, 2007. A total of 357 patients were enrolled, and 347 had successful device implantations. After 12 months, 96.8% had complete echocardiographic closure (OPC = 85%) and 98.1% had clinical closure (OPC = 95%). There were no deaths or serious adverse events (OPC = 1%). The total adverse event rate was 4.7% (OPC = 6%). Composite success was 95.1% in the study patients (OPC = 80%). Closure of small- and medium-sized PDA with the Nit-Occlud PDA is effective and safe when compared with OPC. Copyright © 2014 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Implications of Natural Occlusion of Ventilated Racks on Ammonia and Sanitation Practices

PubMed Central

Creamer, Michelle A; Petty, Joann; Martin, Tara; Bergdall, Valerie; Hickman-Davis, Judy M

2014-01-01

Examination of ventilated rat racks prior to semiannual sanitation revealed silicone nozzles and ventilation ports that were partially or completely occluded with granular debris. We subsequently sought to document performance standards for rack sanitation and investigate the effect of ventilation port occlusion on rack function and animal husbandry practices. We hypothesized that individually ventilated cages with occluded airflow would require more frequent cage changes, comparable to those for static cages (that is, every 3 to 4 d). Sprague–Dawley rats were housed under one of 4 conditions: no airflow occlusion, occluded air-supply inlet, occluded air-exhaust outlet, and occlusion of both inlet and outlet. Cages were changed when daily ammonia concentration exceeded 20 ppm or after 14 d had elapsed. Most cages with unoccluded or partial airflow occlusion remained below the 20 ppm limit until day 12 or 13. Cages with occlusion of both inlet and outlet exceeded 20 ppm ammonia by as early as day 5. Airflow was significantly lower in cages with occlusion of both inlet and outlet airflow. Weekly inspection revealed that occlusion of ventilation ports was detectable by 3 mo after semiannual sanitation. This study demonstrates that silicone nozzles should be removed prior to rack sanitation to improve the effectiveness of cleaning ventilation ports and nozzles. While the rack is in use, silicone nozzles and ventilation ports should be inspected regularly to identify occlusion that is likely to diminish environmental quality in the cage. Intracage ammonia levels are significantly higher when both inlet and outlet airflow are occluded. PMID:24602544

Implications of natural occlusion of ventilated racks on ammonia and sanitation practices.

PubMed

Creamer, Michelle A; Petty, Joann; Martin, Tara; Bergdall, Valerie; Hickman-Davis, Judy M

2014-03-01

Examination of ventilated rat racks prior to semiannual sanitation revealed silicone nozzles and ventilation ports that were partially or completely occluded with granular debris. We subsequently sought to document performance standards for rack sanitation and investigate the effect of ventilation port occlusion on rack function and animal husbandry practices. We hypothesized that individually ventilated cages with occluded airflow would require more frequent cage changes, comparable to those for static cages (that is, every 3 to 4 d). Sprague-Dawley rats were housed under one of 4 conditions: no airflow occlusion, occluded air-supply inlet, occluded air-exhaust outlet, and occlusion of both inlet and outlet. Cages were changed when daily ammonia concentration exceeded 20 ppm or after 14 d had elapsed. Most cages with unoccluded or partial airflow occlusion remained below the 20 ppm limit until day 12 or 13. Cages with occlusion of both inlet and outlet exceeded 20 ppm ammonia by as early as day 5. Airflow was significantly lower in cages with occlusion of both inlet and outlet airflow. Weekly inspection revealed that occlusion of ventilation ports was detectable by 3 mo after semiannual sanitation. This study demonstrates that silicone nozzles should be removed prior to rack sanitation to improve the effectiveness of cleaning ventilation ports and nozzles. While the rack is in use, silicone nozzles and ventilation ports should be inspected regularly to identify occlusion that is likely to diminish environmental quality in the cage. Intracage ammonia levels are significantly higher when both inlet and outlet airflow are occluded.

Multi-cored vortices support function of slotted wing tips of birds in gliding and flapping flight.

PubMed

KleinHeerenbrink, Marco; Johansson, L Christoffer; Hedenström, Anders

2017-05-01

Slotted wing tips of birds are commonly considered an adaptation to improve soaring performance, despite their presence in species that neither soar nor glide. We used particle image velocimetry to measure the airflow around the slotted wing tip of a jackdaw ( Corvus monedula ) as well as in its wake during unrestrained flight in a wind tunnel. The separated primary feathers produce individual wakes, confirming a multi-slotted function, in both gliding and flapping flight. The resulting multi-cored wingtip vortex represents a spreading of vorticity, which has previously been suggested as indicative of increased aerodynamic efficiency. Considering benefits of the slotted wing tips that are specific to flapping flight combined with the wide phylogenetic occurrence of this configuration, we propose the hypothesis that slotted wings evolved initially to improve performance in powered flight. © 2017 The Author(s).

Effect of Electric Field Gradient on Sub-nanometer Spatial Resolution of Tip-enhanced Raman Spectroscopy

PubMed Central

Meng, Lingyan; Yang, Zhilin; Chen, Jianing; Sun, Mengtao

2015-01-01

Tip-enhanced Raman spectroscopy (TERS) with sub-nanometer spatial resolution has been recently demonstrated experimentally. However, the physical mechanism underlying is still under discussion. Here we theoretically investigate the electric field gradient of a coupled tip-substrate system. Our calculations suggest that the ultra-high spatial resolution of TERS can be partially attributed to the electric field gradient effect owning to its tighter spatial confinement and sensitivity to the infrared (IR)-active of molecules. Particularly, in the case of TERS of flat-lying H2TBPP molecules,we find the electric field gradient enhancement is the dominating factor for the high spatial resolution, which qualitatively coincides with previous experimental report. Our theoretical study offers a new paradigm for understanding the mechanisms of the ultra-high spatial resolution demonstrated in tip-enhanced spectroscopy which is of importance but neglected. PMID:25784161

Structure of the bacteriophage T4 long tail fiber receptor-binding tip

PubMed Central

Bartual, Sergio G.; Otero, José M.; Garcia-Doval, Carmela; Llamas-Saiz, Antonio L.; Kahn, Richard; Fox, Gavin C.; van Raaij, Mark J.

2010-01-01

Bacteriophages are the most numerous organisms in the biosphere. In spite of their biological significance and the spectrum of potential applications, little high-resolution structural detail is available on their receptor-binding fibers. Here we present the crystal structure of the receptor-binding tip of the bacteriophage T4 long tail fiber, which is highly homologous to the tip of the bacteriophage lambda side tail fibers. This structure reveals an unusual elongated six-stranded antiparallel beta-strand needle domain containing seven iron ions coordinated by histidine residues arranged colinearly along the core of the biological unit. At the end of the tip, the three chains intertwine forming a broader head domain, which contains the putative receptor interaction site. The structure reveals a previously unknown beta-structured fibrous fold, provides insights into the remarkable stability of the fiber, and suggests a framework for mutations to expand or modulate receptor-binding specificity. PMID:21041684

Label-free optical imaging of membrane patches for atomic force microscopy

PubMed Central

Churnside, Allison B.; King, Gavin M.; Perkins, Thomas T.

2010-01-01

In atomic force microscopy (AFM), finding sparsely distributed regions of interest can be difficult and time-consuming. Typically, the tip is scanned until the desired object is located. This process can mechanically or chemically degrade the tip, as well as damage fragile biological samples. Protein assemblies can be detected using the back-scattered light from a focused laser beam. We previously used back-scattered light from a pair of laser foci to stabilize an AFM. In the present work, we integrate these techniques to optically image patches of purple membranes prior to AFM investigation. These rapidly acquired optical images were aligned to the subsequent AFM images to ~40 nm, since the tip position was aligned to the optical axis of the imaging laser. Thus, this label-free imaging efficiently locates sparsely distributed protein assemblies for subsequent AFM study while simultaneously minimizing degradation of the tip and the sample. PMID:21164738

Touching up Mental Rotation: Effects of Manual Experience on 6-Month-Old Infants' Mental Object Rotation

ERIC Educational Resources Information Center

Möhring, Wenke; Frick, Andrea

2013-01-01

In this study, 6-month-olds' ability to mentally rotate objects was investigated using the violation-of-expectation paradigm. Forty infants watched an asymmetric object being moved straight down behind an occluder. When the occluder was lowered, it revealed the original object (possible) or its mirror image (impossible) in one of five…

A Randomized Controlled Trial of Two Semi-Occluded Vocal Tract Voice Therapy Protocols

ERIC Educational Resources Information Center

Kapsner-Smith, Mara R.; Hunter, Eric J.; Kirkham, Kimberly; Cox, Karin; Titze, Ingo R.

2015-01-01

Purpose: Although there is a long history of use of semi-occluded vocal tract gestures in voice therapy, including phonation through thin tubes or straws, the efficacy of phonation through tubes has not been established. This study compares results from a therapy program on the basis of phonation through a flow-resistant tube (FRT) with Vocal…

The Case of the Missing Visual Details: Occlusion and Long-Term Visual Memory

ERIC Educational Resources Information Center

Williams, Carrick C.; Burkle, Kyle A.

2017-01-01

To investigate the critical information in long-term visual memory representations of objects, we used occlusion to emphasize 1 type of information or another. By occluding 1 solid side of the object (e.g., top 50%) or by occluding 50% of the object with stripes (like a picket fence), we emphasized visible information about the object, processing…

Rhythmic neural activity indicates the contribution of attention and memory to the processing of occluded movements in 10-month-old infants.

PubMed

Bache, Cathleen; Kopp, Franziska; Springer, Anne; Stadler, Waltraud; Lindenberger, Ulman; Werkle-Bergner, Markus

2015-11-01

Infants possess the remarkable capacity to perceive occluded movements as ongoing and coherent. Little is known about the neural mechanisms that enable internal representation of conspecifics' and inanimate objects' movements during visual occlusion. In this study, 10-month-old infants watched briefly occluded human and object movements. Prior to occlusion, continuous and distorted versions of the movement were shown. EEG recordings were used to assess neural activity assumed to relate to processes of attention (occipital alpha), memory (frontal theta), and sensorimotor simulation (central alpha) before, during, and after occlusion. Oscillatory activity was analyzed using an individualized data approach taking idiosyncrasies into account. Results for occipital alpha were consistent with infants' preference for attending to social stimuli. Furthermore, frontal theta activity was more pronounced when tracking distorted as opposed to continuous movement, and when maintaining object as opposed to human movement. Central alpha did not discriminate between experimental conditions. In sum, we conclude that observing occluded movements recruits processes of attention and memory which are modulated by stimulus and movement properties. Copyright © 2015 Elsevier B.V. All rights reserved.

Template occluded SBA-15: An effective dissolution enhancer for poorly water-soluble drug

NASA Astrophysics Data System (ADS)

Tingming, Fu; Liwei, Guo; Kang, Le; Tianyao, Wang; Jin, Lu

2010-09-01

The aim of the present work was to improve the dissolution rate of piroxicam by inclusion into template occluded SBA-15. Our strategy involves directly introducing piroxicam into as-prepared SBA-15 occluded with P123 (EO 20PO 70EO 20) by self assembling method in acetonitrile/methylene chloride mixture solution. Ultraviolet spectrometry experiment and thermogravimetric analysis-differential scanning calorimetry (TG-DSC) profiles show that the piroxicam and P123 contents in the inclusion compound are 12 wt% and 28 wt%, respectively. X-ray powder diffraction and DSC analysis reveal that the included piroxicam is arranged in amorphous form. N 2 adsorption-desorption experiment indicates that the piroxicam has been introduced to the mesopores instead of precipitating at the outside of the silica material. The inclusion compound was submitted to in vitro dissolution tests, the results show that the piroxicam dissolve from template occluded inclusion compound more rapidly, than these from the piroxicam crystalline and template removed samples in all tested conditions. Thus a facile method to improve the dissolution rate of poorly water-soluble drug was established, and this discovery opens a new avenue for the utilization of templates used for the synthesis of mesoporous materials.

Structural Basis for the Kexin-like Serine Protease from Aeromonas sobria as Sepsis-causing Factor*

PubMed Central

Kobayashi, Hidetomo; Utsunomiya, Hiroko; Yamanaka, Hiroyasu; Sei, Yoshihisa; Katunuma, Nobuhiko; Okamoto, Keinosuke; Tsuge, Hideaki

2009-01-01

The anaerobic bacterium Aeromonas sobria is known to cause potentially lethal septic shock. We recently proposed that A. sobria serine protease (ASP) is a sepsis-related factor that induces vascular leakage, reductions in blood pressure via kinin release, and clotting via activation of prothrombin. ASP preferentially cleaves peptide bonds that follow dibasic amino acid residues, as do Kex2 (Saccharomyces cerevisiae serine protease) and furin, which are representative kexin family proteases. Here, we revealed the crystal structure of ASP at 1.65 Å resolution using the multiple isomorphous replacement method with anomalous scattering. Although the overall structure of ASP resembles that of Kex2, it has a unique extra occluding region close to its active site. Moreover, we found that a nicked ASP variant is cleaved within the occluding region. Nicked ASP shows a greater ability to cleave small peptide substrates than the native enzyme. On the other hand, the cleavage pattern for prekallikrein differs from that of ASP, suggesting the occluding region is important for substrate recognition. The extra occluding region of ASP is unique and could serve as a useful target to facilitate development of novel antisepsis drugs. PMID:19654332

Decision and cost-utility analyses of surgical versus transcatheter closure of patent ductus arteriosus: should you let a smile be your umbrella?

PubMed

Gray, D T; Weinstein, M C

1998-01-01

Decision and cost-utility analyses considered the tradeoffs of treating patent ductus arteriosus (PDA) using conventional surgery versus transcatheter implantation of the Rashkind occluder. Physicians and informed lay parents assigned utility scores to procedure success/complications combinations seen in prognostically similar pediatric patients with isolated PDA treated from 1982 to 1987. Utility scores multiplied by outcome frequencies from a comparative study generated expected utility values for the two approaches. Cost-utility analyses combined these results with simulated provider cost estimates from 1989. On a 0-100 scale (worst to best observed outcome), the median expected utility for surgery was 99.96, versus 98.88 for the occluder. Results of most sensitivity analyses also slightly favored surgery. Expected utility differences based on 1987 data were minimal. With a mean overall simulated cost of $8,838 vs $12,466 for the occluder, surgery was favored in most cost-utility analyses. Use of the inherently less invasive but less successful, more risky, and more costly occluder approach conferred no apparent net advantage in this study. Analyses of comparable current data would be informative.

Functional MRI reveals expert-novice differences during sport-related anticipation.

PubMed

Wright, Michael J; Bishop, Daniel T; Jackson, Robin C; Abernethy, Bruce

2010-01-27

We examined the effect of expertise on cortical activation during sports anticipation using functional MRI. In experiment 1, recreational players predicted badminton stroke direction and the pattern of active clusters was consistent with a proposed perception-of-action network. This pattern was not replicated in a stimulus-matched, action-unrelated control task. In experiment 2, players of three different skill levels anticipated stroke direction from clips occluded either 160 ms before or 80 ms after racquet-shuttle contact. Early-occluded sequences produced more activation than late-occluded sequences overall, in most cortical regions of interest, but experts showed an additional enhancement in medial, dorsolateral and ventrolateral frontal cortex. Anticipation in open-skill sports engages cortical areas integral to observing and understanding others' actions; such activity is enhanced in experts.

Transcatheter closure of left ventricle to right atrial communication using cera duct occluder.

PubMed

Ganesan, Gnanavelu; Paul, G Justin; Mahadevan, Vaikom S

Left ventricle-right atrial communication could be congenital (Gerbode defect) or acquired as a complication of surgery or infective endocarditis and leads to volume overloading of pulmonary circulation. Two types, direct and indirect types are known depending on the involvement of septal tricuspid leaflet. Transcatheter closure of this defect is feasible and appears an attractive alternative to surgical management. Various devices like Amplatzer duct occluder I, II, Muscular ventricular septal defect device etc. have been used to close this defect. We report two patients, a preteen boy with direct left ventricle-right atrial communication as post operative complication and an adult female with indirect communication who underwent transcatheter closure with Cera duct occluder (Lifetech Scientific (Shenzhen), China). Copyright © 2017. Published by Elsevier B.V.

Hemolysis induced by PMIVSD occluder.

PubMed

Rao, D Sheshagiri; Barik, Ramachandra; Siva Prasad, Akula

2016-09-01

Hemolysis related to occluder, prosthetic valve, and prosthetic ring used for mitral valve annuloplasty are not very unusual. However, hemolysis related to transcathetor closure of post-myocardial infarction ventricular septal defect (PMIVSD) is infrequent. A close follow-up for spontaneous resolution with or without blood transfusion has been reported in a few cases. Occasionally, surgical retrieval is unavoidable or lifelong blood transfusion is required if surgery cannot be done because of higher risk. In this illustration, we have showed a close follow-up of a case of hemolysis induced by atrial septal occluder used for VSD closure after myocardial infarction. Despite successful device closure of PMIVSD which is difficult, a close watch is needed for complications like residual leak, device embolization, and hemolysis. Copyright © 2016 Cardiological Society of India. Published by Elsevier B.V. All rights reserved.

Amplatzer angled duct occluder for closure of patent ductus arteriosus larger than the aorta in an infant.

PubMed

Vijayalakshmi, I B; Chitra, N; Rajasri, R; Prabhudeva, A N

2005-01-01

Transcatheter closure of patent ductus arteriosus (PDA) by Amplatzer duct occluder is the treatment of choice. However, closure of very large ducts in infants with low weight is a challenge for the interventionalist because a large device may obstruct the aorta or left pulmonary artery. Difficulty is also encountered in advancing the device around the curve of the right ventricular outflow tract toward the pulmonary artery; this curve is tight, more or less at a right angle in infants, leading to kinking of the sheath, which increases fluoroscopic time. This is the first reported case of a very large PDA (8.7 mm), larger than the aorta (8.2 mm), successfully closed by an Amplatzer angled duct occluder in an infant weighing 5 kg.

Translation in cardiovascular stents and occluders: From biostable to fully degradable

PubMed Central

Huang, Yingying; Wong, Yee Shan; Ng, Herr Cheun Anthony; Boey, Freddy Y. C.

2017-01-01

Abstract Cardiovascular disease is a major cause of morbidity and mortality, especially in developed countries. Most academic research efforts in cardiovascular disease management focus on pharmacological interventions, or are concerned with discovering new disease markers for diagnosis and monitoring. Nonpharmacological interventions with therapeutic devices, conversely, are driven largely by novel materials and device design. Examples of such devices include coronary stents, heart valves, ventricular assist devices, and occluders for septal defects. Until recently, development of such devices remained largely with medical device companies. We trace the materials evolution story in two of these devices (stents and occluders), while also highlighting academic contributions, including our own, to the evolution story. Specifically, it addresses not only our successes, but also the challenges facing the translatability of concepts generated via academic research. PMID:29313029

Transcatheter Closure of a Chronic Iatrogenic Arteriovenous Fistula Between the Carotid Artery and the Brachiocephalic Vein with an Amplatzer Duct Occluder in Combination with a Carotid Stent

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

Stasek, Josef, E-mail: stasek@fnhk.c; Lojik, Miroslav; Bis, Josef

2009-05-15

We report an original method of transcatheter closure of an arteriovenous fistula using the combination of an Amplatzer PDA occluder and a carotid stent. The fistula was between the left carotid artery and the brachiocephalic vein. The patient had significant left-to-right shunt and was highly symptomatic. Due to the large orifice and pseudoaneurysmatic enlargement of the fistula, we had to use a large Amplatzer PDA occluder and the protruding part of the PDA device disk had to be covered with a carotid stent. The fistula was completely closed. The patient stopped having symptoms and, 2 years after the procedure, themore » effect persists.« less

Pattering of nanostructures with high aspect ratio in polymer materials

NASA Astrophysics Data System (ADS)

Lyuksyutov, Sergei; Paramonov, Pavel; Sancaktar, Erol; Vaia, Richard; Juhl, Shane

2004-04-01

The generation of features larger than the initial atomic force microscope (AFM) tip-surface distance (presumably less that 1nm for unbiased tip) had previously been reported for silicon and metal oxidation. Such nanostructure (1-50 nm high) formation exceeding AFM tip-sample separation has been observed by us during AFM-assisted nanolithography in polymers [1,2]. The technique produces nanostructures up to 100 nm high in thin (10-30 nm) polymer films through the one-step process. The specific spatial details of the tip-surface contact profile, as well as cantilever motion, with applied bias during writing is not well understood and we are not aware of any comprehensive explanation provided in literature for this effect. In this work we analyze tip-polymer interaction using real-time tip deflection. An abrupt lift-up of biased AFM tip has been recorded experimentally and found to be proportional to the height of polymer nanostructures. This fact was used to pattern robust nanostructures of 20-100 nm high using amplitude modulated AFM-assisted electrostatic nanolithography [2] as the arrays of dots in polystyrene and polybenzoxasole polymer films. References [1] S.F. Lyuksyutov, R.A. Vaia, P.B. Paramonov, S. Juhl, L. Waterhouse, R.M. Ralich, G. Sigalov, and E. Sancaktar, Nature Materials 2(7) 468-472 (2003) [2] S.F. Lyuksyutov, R.A. Vaia, P.B. Paramonov, and S. Juhl, Appl. Phys. Lett. 83 (21), 4405-4407 (2003)

Measurement and prediction of model-rotor flow fields

NASA Technical Reports Server (NTRS)

Owen, F. K.; Tauber, M. E.

1985-01-01

This paper shows that a laser velocimeter can be used to measure accurately the three-component velocities induced by a model rotor at transonic tip speeds. The measurements, which were made at Mach numbers from 0.85 to 0.95 and at zero advance ratio, yielded high-resolution, orthogonal velocity values. The measured velocities were used to check the ability of the ROT22 full-potential rotor code to predict accurately the transonic flow field in the crucial region around and beyond the tip of a high-speed rotor blade. The good agreement between the calculated and measured velocities established the code's ability to predict the off-blade flow field at transonic tip speeds. This supplements previous comparisons in which surface pressures were shown to be well predicted on two different tips at advance ratios to 0.45, especially at the critical 90 deg azimuthal blade position. These results demonstrate that the ROT22 code can be used with confidence to predict the important tip-region flow field, including the occurrence, strength, and location of shock waves causing high drag and noise.

Pressure-induced transformations in glassy water: A computer simulation study using the TIP4P/2005 model

NASA Astrophysics Data System (ADS)

Wong, Jessina; Jahn, David A.; Giovambattista, Nicolas

2015-08-01

We study the pressure-induced transformations between low-density amorphous (LDA) and high-density amorphous (HDA) ice by performing out-of-equilibrium molecular dynamics (MD) simulations. We employ the TIP4P/2005 water model and show that this model reproduces qualitatively the LDA-HDA transformations observed experimentally. Specifically, the TIP4P/2005 model reproduces remarkably well the (i) structure (OO, OH, and HH radial distribution functions) and (ii) densities of LDA and HDA at P = 0.1 MPa and T = 80 K, as well as (iii) the qualitative behavior of ρ(P) during compression-induced LDA-to-HDA and decompression-induced HDA-to-LDA transformations. At the rates explored, the HDA-to-LDA transformation is less pronounced than in experiments. By studying the LDA-HDA transformations for a broad range of compression/decompression temperatures, we construct a "P-T phase diagram" for glassy water that is consistent with experiments and remarkably similar to that reported previously for ST2 water. This phase diagram is not inconsistent with the possibility of TIP4P/2005 water exhibiting a liquid-liquid phase transition at low temperatures. A comparison with previous MD simulation studies of SPC/E and ST2 water as well as experiments indicates that, overall, the TIP4P/2005 model performs better than the SPC/E and ST2 models. The effects of cooling and compression rates as well as aging on our MD simulations results are also discussed. The MD results are qualitatively robust under variations of cooling/compression rates (accessible in simulations) and are not affected by aging the hyperquenched glass for at least 1 μs. A byproduct of this work is the calculation of TIP4P/2005 water's diffusion coefficient D(T) at P = 0.1 MPa. It is found that, for T ≥ 210 K, D(T) ≈ (T - TMCT)-γ as predicted by mode coupling theory and in agreement with experiments. For TIP4P/2005 water, TMCT = 209 K and γ = 2.14, very close to the corresponding experimental values TMCT = 221 K and γ = 2.2.

Pressure-induced transformations in glassy water: A computer simulation study using the TIP4P/2005 model.

PubMed

Wong, Jessina; Jahn, David A; Giovambattista, Nicolas

2015-08-21

We study the pressure-induced transformations between low-density amorphous (LDA) and high-density amorphous (HDA) ice by performing out-of-equilibrium molecular dynamics (MD) simulations. We employ the TIP4P/2005 water model and show that this model reproduces qualitatively the LDA-HDA transformations observed experimentally. Specifically, the TIP4P/2005 model reproduces remarkably well the (i) structure (OO, OH, and HH radial distribution functions) and (ii) densities of LDA and HDA at P = 0.1 MPa and T = 80 K, as well as (iii) the qualitative behavior of ρ(P) during compression-induced LDA-to-HDA and decompression-induced HDA-to-LDA transformations. At the rates explored, the HDA-to-LDA transformation is less pronounced than in experiments. By studying the LDA-HDA transformations for a broad range of compression/decompression temperatures, we construct a "P-T phase diagram" for glassy water that is consistent with experiments and remarkably similar to that reported previously for ST2 water. This phase diagram is not inconsistent with the possibility of TIP4P/2005 water exhibiting a liquid-liquid phase transition at low temperatures. A comparison with previous MD simulation studies of SPC/E and ST2 water as well as experiments indicates that, overall, the TIP4P/2005 model performs better than the SPC/E and ST2 models. The effects of cooling and compression rates as well as aging on our MD simulations results are also discussed. The MD results are qualitatively robust under variations of cooling/compression rates (accessible in simulations) and are not affected by aging the hyperquenched glass for at least 1 μs. A byproduct of this work is the calculation of TIP4P/2005 water's diffusion coefficient D(T) at P = 0.1 MPa. It is found that, for T ≥ 210 K, D(T) ≈ (T - T(MCT))(-γ) as predicted by mode coupling theory and in agreement with experiments. For TIP4P/2005 water, T(MCT) = 209 K and γ = 2.14, very close to the corresponding experimental values T(MCT) = 221 K and γ = 2.2.

Analysis of Unsteady Tip and Endwall Heat Transfer in a Highly Loaded Transonic Turbine Stage

NASA Technical Reports Server (NTRS)

Shyam, Vikram; Ameri, Ali; Chen, Jen-Ping

2010-01-01

In a previous study, vane-rotor shock interactions and heat transfer on the rotor blade of a highly loaded transonic turbine stage were simulated. The geometry consists of a high pressure turbine vane and downstream rotor blade. This study focuses on the physics of flow and heat transfer in the rotor tip, casing and hub regions. The simulation was performed using the Unsteady Reynolds-Averaged Navier-Stokes (URANS) code MSU-TURBO. A low Reynolds number k-epsilon model was utilized to model turbulence. The rotor blade in question has a tip gap height of 2.1 percent of the blade height. The Reynolds number of the flow is approximately 3x10(exp 6) per meter. Unsteadiness was observed at the tip surface that results in intermittent "hot spots". It is demonstrated that unsteadiness in the tip gap is governed by inviscid effects due to high speed flow and is not strongly dependent on pressure ratio across the tip gap contrary to published observations that have primarily dealt with subsonic tip flows. The high relative Mach numbers in the tip gap lead to a choking of the leakage flow that translates to a relative attenuation of losses at higher loading. The efficacy of new tip geometry is discussed to minimize heat flux at the tip while maintaining choked conditions. In addition, an explanation is provided that shows the mechanism behind the rise in stagnation temperature on the casing to values above the absolute total temperature at the inlet. It is concluded that even in steady mode, work transfer to the near tip fluid occurs due to relative shearing by the casing. This is believed to be the first such explanation of the work transfer phenomenon in the open literature. The difference in pattern between steady and time-averaged heat flux at the hub is also explained.

Fiber optic muzzle brake tip for reducing fiber burnback and stone retropulsion during thulium fiber laser lithotripsy

NASA Astrophysics Data System (ADS)

Hutchens, Thomas C.; Gonzalez, David A.; Irby, Pierce B.; Fried, Nathaniel M.

2017-01-01

The experimental thulium fiber laser (TFL) is being explored as an alternative to the current clinical gold standard Holmium:YAG laser for lithotripsy. The near single-mode TFL beam allows coupling of higher power into smaller optical fibers than the multimode Holmium laser beam profile, without proximal fiber tip degradation. A smaller fiber is desirable because it provides more space in the ureteroscope working channel for increased saline irrigation rates and allows maximum ureteroscope deflection. However, distal fiber tip burnback increases as fiber diameter decreases. Previous studies utilizing hollow steel sheaths around recessed distal fiber tips reduced fiber burnback but increased stone retropulsion. A "fiber muzzle brake" was tested for reducing both fiber burnback and stone retropulsion by manipulating vapor bubble expansion. TFL lithotripsy studies were performed at 1908 nm, 35 mJ, 500 μs, and 300 Hz using a 100-μm-core fiber. The optimal stainless steel muzzle brake tip tested consisted of a 1-cm-long, 560-μm-outer-diameter, 360-μm-inner-diameter tube with a 275-μm-diameter through hole located 250 μm from the distal end. The fiber tip was recessed a distance of 500 μm. Stone phantom retropulsion, fiber tip burnback, and calcium oxalate stone ablation studies were performed ex vivo. Small stones with a mass of 40±4 mg and 4-mm-diameter were ablated over a 1.5-mm sieve in 25±4 s (n=10) without visible distal fiber tip burnback. Reduction in stone phantom retropulsion distance by 50% and 85% was observed when using muzzle brake tips versus 100-μm-core bare fibers and hollow steel tip fibers, respectively. The muzzle brake fiber tip simultaneously provided efficient stone ablation, reduced stone retropulsion, and minimal fiber degradation during TFL lithotripsy.

Evidence That Rhesus Macaques Self-Cure from a Schistosoma japonicum Infection by Disrupting Worm Esophageal Function: A New Route to an Effective Vaccine?

PubMed Central

Li, Xiao-Hong; Xu, Yu-Xin; Vance, Gill; Wang, Yun; Lv, Long-Bao; van Dam, Govert J.; Cao, Jian-Ping; Wilson, R. Alan

2015-01-01

Background Rhesus macaques are unusual among schistosome hosts, self-curing from an established infection and thereafter manifesting solid immunity against a challenge, an ideal model for vaccine development. Previously, the immunological basis of self-cure was confirmed; surviving worms had ceased feeding but how immunological pressure achieved this was unclear. The schistosome esophagus is not simply a conduit for blood but plays a central role in its processing. Secretions from the anterior and posterior esophageal glands mix with incoming blood causing erythrocyte lysis and tethering and killing of leucocytes. Methodology/Principal Findings We have analysed the self-cure process in rhesus macaques infected with Schistosoma japonicum. Faecal egg output and circulating antigen levels were used to chart the establishment of a mature worm population and its subsequent demise. The physiological stress of surviving females at perfusion was especially evident from their pale, shrunken appearance, while changes in the structure and function of the esophagus were observed in both sexes. In the anterior region electron microscopy revealed that the vesicle secretory process was disrupted, the tips of lining corrugations being swollen by greatly enlarged vesicles and the putative sites of vesicle release obscured by intense deposits of IgG. The lumen of the posterior esophagus in starving worms was occluded by cellular debris and the lining cytoplasmic plates were closely adherent, also potentially preventing secretion. Seven proteins secreted by the posterior gland were identified and IgG responses were detected to some or all of them. Intrinsic rhesus IgG colocalized with secreted SjMEGs 4.1, 8.2, 9, 11 and VAL-7 on cryosections, suggesting they are potential targets for disruption of function. Conclusions/Significance Our data suggest that rhesus macaques self-cure by blocking esophagus function with antibody; the protein products of the glands provide a new class of potential vaccine targets. PMID:26161644

Computational Modeling of Blood Flow in the TrapEase Inferior Vena Cava Filter

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

Singer, M A; Henshaw, W D; Wang, S L

To evaluate the flow hemodynamics of the TrapEase vena cava filter using three dimensional computational fluid dynamics, including simulated thrombi of multiple shapes, sizes, and trapping positions. The study was performed to identify potential areas of recirculation and stagnation and areas in which trapped thrombi may influence intrafilter thrombosis. Computer models of the TrapEase filter, thrombi (volumes ranging from 0.25mL to 2mL, 3 different shapes), and a 23mm diameter cava were constructed. The hemodynamics of steady-state flow at Reynolds number 600 was examined for the unoccluded and partially occluded filter. Axial velocity contours and wall shear stresses were computed. Flowmore » in the unoccluded TrapEase filter experienced minimal disruption, except near the superior and inferior tips where low velocity flow was observed. For spherical thrombi in the superior trapping position, stagnant and recirculating flow was observed downstream of the thrombus; the volume of stagnant flow and the peak wall shear stress increased monotonically with thrombus volume. For inferiorly trapped spherical thrombi, marked disruption to the flow was observed along the cava wall ipsilateral to the thrombus and in the interior of the filter. Spherically shaped thrombus produced a lower peak wall shear stress than conically shaped thrombus and a larger peak stress than ellipsoidal thrombus. We have designed and constructed a computer model of the flow hemodynamics of the TrapEase IVC filter with varying shapes, sizes, and positions of thrombi. The computer model offers several advantages over in vitro techniques including: improved resolution, ease of evaluating different thrombus sizes and shapes, and easy adaptation for new filter designs and flow parameters. Results from the model also support a previously reported finding from photochromic experiments that suggest the inferior trapping position of the TrapEase IVC filter leads to an intra-filter region of recirculating/stagnant flow with very low shear stress that may be thrombogenic.« less

An Experimental Technique for Developing Intermediate Strain Rates in Ductile Metals

DTIC Science & Technology

2008-03-01

Smooth the surface of the specimen in the area of the gauge application to provide a surface finish which pro- motes optimum bonding by the adhe- sive...surface of any contamina- tion caused by previous operations such as marking or abrading Conditioner and Cotton Tipped Applicators 5. Neutralizing...Neutralize the surface so the pH of the surface is returned to 7 eliminating any remaining acidity on the specimen surface Neutralizer and Cotton Tipped

Recovery patterns, histological observations and genetic integrity in Malus shoot tips cryopreserved using droplet-vitrification and encapsulation-dehydration procedures.

PubMed

Li, Bai-Quan; Feng, Chao-Hong; Wang, Min-Rui; Hu, Ling-Yun; Volk, Gayle; Wang, Qiao-Chun

2015-11-20

A droplet-vitrification procedure is described for cryopreservation of Malus shoot tips. Survival patterns, recovery types, histological observations, and genetic integrity were compared for Malus shoot tips cryopreserved using this droplet-vitrification procedure and an encapsulation-dehydration procedure that was previously reported by us. In both procedures, three types of shoot tip recovery were observed following cryopreservation: callus formation without shoot regrowth, leaf formation without shoot regrowth, and shoot regrowth. Three categories of histological observations were also identified in cross-sections of shoot tips recovered after cryopreservation using the two cryogenic procedures. In category 1, almost all of the cells (94-95%) in the apical dome (AD) were damaged or killed and only some cells (30-32%) in the leaf primordia (LPs) survived. In category 2, only a few cells (18-20%) in the AD and some cells (30-31%) in the LPs survived. In category 3, majority of the cells (60-62%) in the AD and some cells (30-33%) in the LPs survived. These data suggest that shoot regrowth is correlated to the presence of a majority of surviving cells in the AD after liquid nitrogen exposure. No polymorphic bands were detected by inter-simple sequence repeats or by random amplified polymorphic DNA assessments, and ploidy levels analyzed by flow cytometry were unchanged when plants recovered after cryoexposure were compared to controls. The droplet-vitrification procedure appears to be robust since seven genotypes representing four Malus species and one hybrid recovered shoots following cryopreservation. Mean shoot regrowth levels of these seven genotypes were 48% in the droplet-vitrification method, which were lower than those (61%) in the encapsulation-dehydration procedure reported in our previous study, suggesting the latter may be preferred for routine cryobanking applications for Malus shoot tips. Copyright © 2015 Elsevier B.V. All rights reserved.

Measurement of vortex velocities over a wide range of vortex age, downstream distance and free stream velocity

NASA Technical Reports Server (NTRS)

Rorke, J. B.; Moffett, R. C.

1977-01-01

A wind tunnel test was conducted to obtain vortex velocity signatures over a wide parameter range encompassing the data conditions of several previous researchers while maintaining a common instrumentation and test facility. The generating wing panel was configured with both a revolved airfoil tip shape and a square tip shape and had a semispan aspect of 4.05/1.0 with a 121.9 cm span. Free stream velocity was varied from 6.1 m/sec to 76.2 m/sec and the vortex core velocities were measured at locations 3, 6, 12, 24 and 48 chordlengths downstream of the wing trailing edge, yielding vortex ages up to 2.0 seconds. Wing pitch angles of 6, 8, 9 and 12 deg were investigated. Detailed surface pressure distributions and wing force measurements were obtained for each wing tip configuration. Correlation with vortex velocity data taken in previous experiments is good. During the rollup process, vortex core parameters appear to be dependent primarily on vortex age. Trending in the plateau and decay regions is more complex and the machanisms appear to be more unstable.

Reversible mechano-electrochemical writing of metallic nanostructures with the tip of an atomic force microscope.

PubMed

Obermair, Christian; Kress, Marina; Wagner, Andreas; Schimmel, Thomas

2012-01-01

We recently introduced a method that allows the controlled deposition of nanoscale metallic patterns at defined locations using the tip of an atomic force microscope (AFM) as a "mechano-electrochemical pen", locally activating a passivated substrate surface for site-selective electrochemical deposition. Here, we demonstrate the reversibility of this process and study the long-term stability of the resulting metallic structures. The remarkable stability for more than 1.5 years under ambient air without any observable changes can be attributed to self-passivation. After AFM-activated electrochemical deposition of copper nanostructures on a polycrystalline gold film and subsequent AFM imaging, the copper nanostructures could be dissolved by reversing the electrochemical potential. Subsequent AFM-tip-activated deposition of different copper nanostructures at the same location where the previous structures were deleted, shows that there is no observable memory effect, i.e., no effect of the previous writing process on the subsequent writing process. Thus, the four processes required for reversible information storage, "write", "read", "delete" and "re-write", were successfully demonstrated on the nanometer scale.

Reversible mechano-electrochemical writing of metallic nanostructures with the tip of an atomic force microscope

PubMed Central

Kress, Marina; Wagner, Andreas; Schimmel, Thomas

2012-01-01

Summary We recently introduced a method that allows the controlled deposition of nanoscale metallic patterns at defined locations using the tip of an atomic force microscope (AFM) as a “mechano-electrochemical pen”, locally activating a passivated substrate surface for site-selective electrochemical deposition. Here, we demonstrate the reversibility of this process and study the long-term stability of the resulting metallic structures. The remarkable stability for more than 1.5 years under ambient air without any observable changes can be attributed to self-passivation. After AFM-activated electrochemical deposition of copper nanostructures on a polycrystalline gold film and subsequent AFM imaging, the copper nanostructures could be dissolved by reversing the electrochemical potential. Subsequent AFM-tip-activated deposition of different copper nanostructures at the same location where the previous structures were deleted, shows that there is no observable memory effect, i.e., no effect of the previous writing process on the subsequent writing process. Thus, the four processes required for reversible information storage, “write”, “read”, “delete” and “re-write”, were successfully demonstrated on the nanometer scale. PMID:23365795

Septic Complication After Balloon-Occluded Retrograde Transvenous Obliteration of Duodenal Variceal Bleeding

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

Akasaka, Thai; Shibata, Toshiya, E-mail: ksj@kuhp.kyoto-u.ac.jp; Isoda, Hiroyoshi

2010-12-15

We report a 64-year-old woman with duodenal varices who underwent balloon-occluded retrograde transvenous obliteration (B-RTO) complicated by intraprocedural variceal rupture. The patient developed shivering and a fever higher than 40{sup o}C 3 days after the B-RTO procedure. A blood culture grew Entereobacter cloacoe. This case represents a rare septic complication of B-RTO for duodenal varices.

Photodynamic therapy for occluded biliary metal stents

NASA Astrophysics Data System (ADS)

Roche, Joseph V. E.; Krasner, Neville; Sturgess, R.

1999-02-01

In this abstract we describe the use of photodynamic therapy (PDT) to recanalize occluded biliary metal stents. In patients with jaundice secondary to obstructed metal stents PDT was carried out 72 hours after the administration of m THPC. Red laser light at 652 nm was delivered endoscopically at an energy intensity of 50 J/cm. A week later endoscopic retrograde cholangiogram showed complete recanalization of the metal stent.

Efficacy and safety of a single 2 mg dose or 4 mg double dose of alteplase for 50 occluded chest ports using a unique instillation technique

PubMed Central

Sharma, Rajinder P; Ree, Chung Ja; Ree, Alexander

2008-01-01

PURPOSE: To evaluate the effectiveness and safety of a single 2 mg dose or a 4 mg double dose of alteplase for restoring function in occluded chest ports. METHODS: A prospective, open-label, nonblinded study was performed on 40 enrolled patients with a total of 50 chest ports at the Henry Ford Hospital Interventional Radiology Department (Detroid, Michigan, USA). Alteplase (Cathflo Activase; Genentech, USA), a recombinant tissue plasminogen activator produced by recombinant DNA technology, was used to restore the function of 50 occluded chest ports. Occlusion was defined as the inability to withdraw blood freely from the port, or the inability to flush the port easily. A 2 mg (2 mL) dose of alteplase was injected into the port through a Huber needle, using a gentle push and pull technique, and was left to dwell for 30 min. If the port remained occluded after the initial 2 mg alteplase treatment, an additional 2 mg alteplase treatment was administered with the same dwell time of 30 min. If a port had remained occluded despite the above regimen, this outcome would have been considered a failure and the chest port would have required surgical intervention. However, all ports were successfully treated, and no surgical intervention was required. The safety end points included minor or major hemorrhages, such as intracranial hemorrhages, or sepsis. Safety end points were determined by a 24 h follow-up telephone call. RESULTS: Of the 50 chest ports (30 single ports and 10 double ports) treated with alteplase, 36 required 2 mg (72%) and 14 required 4 mg (28%). The efficacy end point was 100% for all chest ports treated, without any adverse events. CONCLUSION: High efficacy and safety rates of restoring function in occluded chest ports were obtained with 2 mg or 4 mg doses of alteplase. Part of this high efficacy rate may be due to the gentle push and pull technique used in the present study. PMID:22477414

Mechanical Evaluation of Unobstructing Magnetic Microactuators for Implantable Ventricular Catheters

PubMed Central

Lee, Hyowon; Kolahi, Kameran; Bergsneider, Marvin; Judy, Jack W.

2017-01-01

Here, we report on the development and evaluation of novel unobstructing magnetic microactuators for maintaining the patency of implantable ventricular catheters used in hydrocephalus application. The treatment of hydrocephalus requires chronic implantation of a shunt system to divert excess cerebrospinal fluid from the brain. These shunt systems suffer from a high failure rate (>40%) within the first year of implantation, often due to biological accumulation. Previously, we have shown that magnetic microactuators can be used to remove biological blockage. The new cantilever-based magnetic microactuator presented in this paper improves upon the previous torsional design using a bimorph to induce a postrelease out-of-plane deflection that will prevent the device from occluding the pore at rest. The mechanical evaluations (i.e., postrelease deflection, static and dynamic responses) of fabricated devices are reported and compared with theoretical values. PMID:29151776

Structure, composition and properties of naturally occurring non-calcified crustacean cuticle.

PubMed

Cribb, B W; Rathmell, A; Charters, R; Rasch, R; Huang, H; Tibbetts, I R

2009-05-01

Crustaceans are known for their hard, calcified exoskeleton; however some regions appear different in colour and opacity. These include leg and cheliped tips in the grapsid crab, Metopograpsus frontalis. The chelipeds and leg tips contain only trace levels of calcium but a significant mass of the halogens, chlorine (Cl) and bromine (Br). In contrast, the carapace is heavily calcified and contains only a trace mass of Cl and no Br. In transverse section across the non-calcified tip regions of cheliped and leg the mass percent of halogens varies with position. As such, the exoskeleton of M. frontalis provides a useful model to examine a possible correlation of halogen concentration with the physical properties of hardness (H) and reduced elastic modulus (E(r)), within a chitin-based matrix. Previously published work suggests a correlation exists between Cl concentration and hardness in similar tissues that contain a metal (e.g. zinc). However, in M. frontalis H and E(r) did not vary significantly across cheliped or leg tip despite differences in halogen concentration. The non-calcified regions of M. frontalis are less hard and less stiff than the carapace but equivalent to values found for insect cuticle lacking metals. Cheliped tips showed a complex morphological layering that differed from leg tips.

Levator alae nasi muscle V-Y island flap for nasal tip reconstruction.

PubMed

La Padula, Simone; Abbate, Vincenzo; Di Monta, Gianluca; Schonauer, Fabrizio

2017-03-01

Nasal tip reconstruction can be very challenging. It requires close attention to skin texture, colour and thickness matching, with the respect of the nasal aesthetic units and symmetry. Flaps are usually preferred to skin grafts where possible. Based on different donor areas, various flaps have been described for reconstruction of this region. Here we present a new V-Y myocutaneous island flap based on the levator alae nasi muscle (LAN muscle) blood supply. This flap may represent an alternative to the nasalis myocutaneous sliding V-Y flap previously described by Rybka. As its pivot point it is located more cranially than the nasalis flap, and it can advance more medially than the Rybka flap, with the possibility of covering larger defects of the nasal tip area, up to 1.8 cm in diameter. Over the past 5 years, 24 patients received nasal tip reconstruction with this flap following the resection of basal cell carcinomas. Good tip projection was maintained, and the aesthetic outcome was satisfactory, with well healed scars. We recommend this technique as an alternative to other flaps for nasal tip defects, especially if paramedian. Copyright © 2016 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

Lack of benefit from percutaneous intervention of persistently occluded infarct arteries after the acute phase of myocardial infarction is time independent: insights from Occluded Artery Trial

PubMed Central

Menon, Venu; Pearte, Camille A.; Buller, Christopher E.; Steg, Ph.Gabriel; Forman, Sandra A.; White, Harvey D.; Marino, Paolo N.; Katritsis, Demosthenes G.; Caramori, Paulo; Lasevitch, Ricardo; Loboz-Grudzien, Krystyna; Zurakowski, Aleksander; Lamas, Gervasio A.; Hochman, Judith S.

2009-01-01

Aims The Occluded Artery Trial (OAT) (n = 2201) showed no benefit for routine percutaneous intervention (PCI) (n = 1101) over medical therapy (MED) (n = 1100) on the combined endpoint of death, myocardial infarction (MI), and class IV heart failure (congestive heart failure) in stable post-MI patients with late occluded infarct-related arteries (IRAs). We evaluated the potential for selective benefit with PCI over MED for patients enrolled early in OAT. Methods and results We explored outcomes with PCI over MED in patients randomized to the ≤3 calendar days and ≤7 calendar days post-MI time windows. Earlier, times to randomization in OAT were associated with higher rates of the combined endpoint (adjusted HR 1.04/day: 99% CI 1.01–1.06; P < 0.001). The 48-month event rates for ≤3 days, ≤7 days post-MI enrolled patients were similar for PCI vs. MED for the combined and individual endpoints. There was no interaction between time to randomization defined as a continuous (P = 0.55) or categorical variable with a cut-point of 3 days (P = 0.98) or 7 days (P = 0.64) post-MI and treatment effect. Conclusion Consistent with overall OAT findings, patients enrolled in the ≤3 day and ≤7 day post-MI time windows derived no benefit with PCI over MED with no interaction between time to randomization and treatment effect. Our findings do not support routine PCI of the occluded IRA in trial-eligible patients even in the earliest 24–72 h time window. PMID:19028780

Endovascular treatment of occluded and stenotic visceral vessels in patients with chronic mesenteric ischemia.

PubMed

Christofi, Georgia; Donas, Konstantinos P; Pitoulias, Georgios A; Torsello, Giovanni; Schwindt, Arne G; Stavroulakis, Konstantinos

2017-02-01

Objective Current evidence in the literature about endovascular treatment (ET) of visceral vessels in patients with chronic mesenterial ischemia (CMI) based on morphological characteristics is limited. The aim of this study was the evaluation of ET in occluded and stenotic visceral vessels. Methods Patients undergoing ET for CMI between November 2000 and November 2012 were included in this retrospective study. Primary measure outcome was the symptom-free survival (SFS). Secondary outcomes were primary (PPR), secondary patency (SPR) rates and technical success rate (TSR). A Cox-regression analysis identified risk factors for the primary and secondary measure outcomes. Results Forty patients were included in the present study (men: 21, mean age: 68). The overall number of vessels with intention-to-treat was 62. Fifty-two visceral arteries (18 occlusions and 34 stenoses) were successfully treated by endovascular means. The overall TSR was 84%. Visceral vessel occlusions and atherosclerotic disease of the superior mesenteric artery (SMA) were identified as independent risk factors for poorer TSR ( p < 0.05). The 12-month SFS was 60%. The overall 12-month PPR and SPR were 71% and 94%, respectively. No significant differences were observed between occluded and stenotic vessels ( p > 0.05) concerning the PPR. On the other hand, the subgroup analysis revealed higher SPR among occluded visceral vessels ( p < 0.001) and coeliac axis lesions ( p < 0.001). Conclusions ET was associated with high incidence of symptoms recurrence despite the satisfying patency rates in both occluded and stenotic vessels. Additionally, visceral vessel occlusion and presence of atherosclerotic lesions in the SMA were associated with poorer TSR.

Design Study of Propulsion and Drive Systems for the Large Civil TiltRotor (LCTR2) Rotorcraft

NASA Technical Reports Server (NTRS)

Robuck, Mark; Wilkerson, Joseph; Zhang, Yiyi; Snyder, Christopher A.; Vonderwell, Daniel

2013-01-01

Boeing, Rolls Royce, and NASA have worked together to complete a parametric sizing study for NASA's Large Civil Tilt Rotor (LCTR2) concept 2nd iteration. Vehicle gross weight and fuel usage were evaluated as propulsion and drive system characteristics were varied to maximize the benefit of reduced rotor tip speed during cruise conditions. The study examined different combinations of engine and gearbox variability to achieve rotor cruise tip speed reductions down to 54% of the hover tip speed. Previous NASA studies identified that a 54% rotor speed reduction in cruise minimizes vehicle gross weight and fuel burn. The LCTR2 was the study baseline for initial sizing. This study included rotor tip speed ratios (cruise to hover) of 100%, 77% and 54% at different combinations of engine RPM and gearbox speed reductions, which were analyzed to achieve the lightest overall vehicle gross weight (GW) at the chosen rotor tip speed ratio. Different engine and gearbox technology levels are applied ranging from commercial off-the-shelf (COTS) engines and gearbox technology to entry-in-service (EIS) dates of 2025 and 2035 to assess the benefits of advanced technology on vehicle gross weight and fuel burn. Interim results were previously reported1. This technical paper extends that work and summarizes the final study results including additional engine and drive system study accomplishments. New vehicle sizing data is presented for engine performance at a single operating speed with a multispeed drive system. Modeling details for LCTR2 vehicle sizing and subject engine and drive sub-systems are presented as well. This study was conducted in support of NASA's Fundamental Aeronautics Program, Subsonic Rotary Wing Project.

Recognition of 3-D Scene with Partially Occluded Objects

NASA Astrophysics Data System (ADS)

Lu, Siwei; Wong, Andrew K. C...

1987-03-01

This paper presents a robot vision system which is capable of recognizing objects in a 3-D scene and interpreting their spatial relation even though some objects in the scene may be partially occluded by other objects. An algorithm is developed to transform the geometric information from the range data into an attributed hypergraph representation (AHR). A hypergraph monomorphism algorithm is then used to compare the AHR of objects in the scene with a set of complete AHR's of prototypes. The capability of identifying connected components and interpreting various types of edges in the 3-D scene enables us to distinguish objects which are partially blocking each other in the scene. Using structural information stored in the primitive area graph, a heuristic hypergraph monomorphism algorithm provides an effective way for recognizing, locating, and interpreting partially occluded objects in the range image.

Reconstruction of a three-dimensional, transonic rotor flow field from holographic interferogram data

NASA Technical Reports Server (NTRS)

Kittleson, John K.; Yu, Yung H.

1987-01-01

Holographic interferometry and computerized aided tomography (CAT) are used to determine the transonic velocity field of a model rotor blade in hover. A pulsed ruby laser recorded 40 interferograms with a 2 ft dia view field near the model rotor blade tip operating at a tip Mach number of 0.90. After digitizing the interferograms and extracting the fringe order functions, the data are transferred to a CAT code. The CAT code then calculates the perturbation velocity in several planes above the blade surface. The values from the holography-CAT method compare favorably with previously obtained numerical computations in most locations near the blade tip. The results demonstrate the technique's potential for three dimensional transonic rotor flow studies.

Vacuum phonon tunneling.

PubMed

Altfeder, Igor; Voevodin, Andrey A; Roy, Ajit K

2010-10-15

Field-induced phonon tunneling, a previously unknown mechanism of interfacial thermal transport, has been revealed by ultrahigh vacuum inelastic scanning tunneling microscopy (STM). Using thermally broadened Fermi-Dirac distribution in the STM tip as in situ atomic-scale thermometer we found that thermal vibrations of the last tip atom are effectively transmitted to sample surface despite few angstroms wide vacuum gap. We show that phonon tunneling is driven by interfacial electric field and thermally vibrating image charges, and its rate is enhanced by surface electron-phonon interaction.

Hydrogen test of a small, low specific speed centrifugal pump stage

NASA Technical Reports Server (NTRS)

1991-01-01

A small, low specific speed centrifugal pump stage with a 2 inch tip diameter, .030 inch tip width shrouded impeller and volute collector was tested with liquid hydrogen as the pumped fluid. The hydrodynamic design of the pump stage is summarized and the noncavitating and cavitating performance results are presented. Test speeds were 60 and 80 percent of the 77,000 rpm design speed. Liquid hydrogen test results are compared with data from previous tests of the stage in water.

Renal Branch Artery Occlusion in a 13-Year-Old Hypertensive Girl: Initial Treatment and Treatment of Recurrent Stenosis by Balloon Angioplasty

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

Konez, Orhan; Burrows, Patricia E.; Harmon, William E.

2001-09-15

A 13-year-old girl who recently developed hypertension was diagnosed to have an occluded right renal branch artery and was treated successfully with percutaneous transluminal angioplasty (PTA). To our knowledge, PTA has not been reported as a treatment for totally occluded renal branch arteries, and there is no data available regarding the success rate and possible complications.

Treatment of patent ductus arteriosus by the use of an Amplatz canine ductal occluder device

PubMed Central

White, Pam

2009-01-01

A 7-month-old female, spayed border collie was referred to the Ontario Veterinary College due to a continuous murmur noted by the referring veterinarian prior to ovariohysterectomy. Auscultation confirmed a grade VI/VI continuous murmur. An echocardiogram confirmed patent ductus arteriosus (PDA). An Amplatz canine ductal occluder device was successfully placed for occlusion of blood flow though the ductus. PMID:19436449

Short-Term Effect of Two Semi-Occluded Vocal Tract Training Programs on the Vocal Quality of Future Occupational Voice Users: "Resonant Voice Training Using Nasal Consonants" versus "Straw Phonation"

ERIC Educational Resources Information Center

Meerschman, Iris; Van Lierde, Kristiane; Peeters, Karen; Meersman, Eline; Claeys, Sofie; D'haeseleer, Evelien

2017-01-01

Purpose: The purpose of this study was to determine the short-term effect of 2 semi-occluded vocal tract training programs, "resonant voice training using nasal consonants" versus "straw phonation," on the vocal quality of vocally healthy future occupational voice users. Method: A multigroup pretest--posttest randomized control…

Reduced Performance of Prey Targeting in Pit Vipers with Contralaterally Occluded Infrared and Visual Senses

PubMed Central

Chen, Qin; Deng, Huanhuan; Brauth, Steven E.; Ding, Li; Tang, Yezhong

2012-01-01

Both visual and infrared (IR) senses are utilized in prey targeting by pit vipers. Visual and IR inputs project to the contralateral optic tectum where they activate both multimodal and bimodal neurons. A series of ocular and pit organ occlusion experiments using the short-tailed pit viper (Gloydius brevicaudus) were conducted to investigate the role of visual and IR information during prey targeting. Compared with unoccluded controls, snakes with either both eyes or pit organs occluded performed more poorly in hunting prey although such subjects still captured prey on 75% of trials. Subjects with one eye and one pit occluded on the same side of the face performed as well as those with bilateral occlusion although these subjects showed a significant targeting angle bias toward the unoccluded side. Performance was significantly poorer when only a single eye or pit was available. Interestingly, when one eye and one pit organ were occluded on opposite sides of the face, performance was poorest, the snakes striking prey on no more than half the trials. These results indicate that, visual and infrared information are both effective in prey targeting in this species, although interference between the two modalities occurs if visual and IR information is restricted to opposite sides of the brain. PMID:22606229

Predictive Coding in Area V4: Dynamic Shape Discrimination under Partial Occlusion

PubMed Central

Choi, Hannah; Pasupathy, Anitha; Shea-Brown, Eric

2018-01-01

The primate visual system has an exquisite ability to discriminate partially occluded shapes. Recent electrophysiological recordings suggest that response dynamics in intermediate visual cortical area V4, shaped by feedback from prefrontal cortex (PFC), may play a key role. To probe the algorithms that may underlie these findings, we build and test a model of V4 and PFC interactions based on a hierarchical predictive coding framework. We propose that probabilistic inference occurs in two steps. Initially, V4 responses are driven solely by bottom-up sensory input and are thus strongly influenced by the level of occlusion. After a delay, V4 responses combine both feedforward input and feedback signals from the PFC; the latter reflect predictions made by PFC about the visual stimulus underlying V4 activity. We find that this model captures key features of V4 and PFC dynamics observed in experiments. Specifically, PFC responses are strongest for occluded stimuli and delayed responses in V4 are less sensitive to occlusion, supporting our hypothesis that the feedback signals from PFC underlie robust discrimination of occluded shapes. Thus, our study proposes that area V4 and PFC participate in hierarchical inference, with feedback signals encoding top-down predictions about occluded shapes. PMID:29566355

Occlusion of Tracheostomy Tubes Does Not Alter Pharyngeal Phase Kinematics But Reduces Penetration by Enhancing Pharyngeal Clearance: A Prospective Study in Patients With Neurogenic Dysphagia.

PubMed

Ledl, Christian; Ullrich, Ylva Yasmin

2017-04-01

Tracheostomy tubes (TT) are often needed in patients with severe neurologic injuries to protect the respiratory system from aspiration. However, TTs alter physiological oral-nasal airflow and are suspected to influence the pattern of pharyngeal swallowing. The aim of this work was to evaluate the effect of TT occlusion on pharyngeal swallowing physiology and to determine penetration-aspiration (PA) values of open versus closed TTs in neurogenic dysphagia. Prospective controlled clinical study with 20 tracheotomized patients after unilateral hemispheric stroke. Pharyngeal manometry and flexible endoscopic evaluation of swallowing were performed simultaneously to determine pharyngoesophageal pressure and timing, as well as PA scores with open and occluded TTs. In each condition, patients had to swallow 5 mL of puree 5 times. Pharyngoesophageal pressure amplitudes, duration, and timing of the swallows did not change as a result of the tracheostomy tube status. Penetration-aspiration values were significantly lower in the occluded tube condition (P = 0.024). Airflow and tracheostomy tube status did not influence the physiology of pharyngoesophageal swallowing in patients with neurogenic dysphagia. However, occluded TTs permitted the voluntary clearance of laryngeal residue and resulted in improved PA scores. We recommend performing dysphagia therapy in tracheotomized patients as soon as possible with uncuffed and occluded tubes.

Alar setback technique: a controlled method of nasal tip deprojection.

PubMed

Foda, H M

2001-11-01

To describe an alar cartilage-modifying technique aimed at decreasing nasal tip projection in cases with overdeveloped alar cartilages and to compare it with other deprojection techniques used to correct such deformity. Selected case series. University and private practice settings in Alexandria, Egypt. Twenty patients presenting for rhinoplasty who had overprojected nasal tips primarily due to overdeveloped alar cartilages. All cases were primary cases except for one patient, who had undergone 2 previous rhinoplasties. An external rhinoplasty approach was used to set back the alar cartilages by shortening their medial and lateral crura. The choice of performing a high or low setback depended on the preexisting lobule-to-columella ratio. Following the setback, the alar cartilages were reconstructed in a fashion that increased the strength and stability of the tip complex. Subjective evaluation included clinical examination, analysis of preoperative and postoperative photographs, and patient satisfaction. Objective evaluation of nasal tip projection, using the Goode ratio and the nasofacial angle, was performed preoperatively and repeated at least 6 months postoperatively. A low setback was performed in 16 cases (80%) and a high setback in 4 (20%). The mean follow-up period was 18 months (range, 6-36 months). The technique effectively deprojected the nasal tip as evidenced by the considerable postoperative decrease in values of the Goode ratio and the nasofacial angle. No complications were encountered and no revision surgical procedures were required. The alar setback technique has many advantages; it results in precise predictable amounts of deprojection, controls the degree of tip rotation, preserves the natural contour of the nasal tip, respects the tip support mechanisms, increases the strength and stability of nasal tip complex, preserves or restores the normal lobule-to-columella proportion, and does not lead to alar flaring. However, the technique requires an external rhinoplasty approach and fine technical precision.

A Parametric Study of Actuator Requirements for Active Turbine Tip Clearance Control of a Modern High Bypass Turbofan Engine

NASA Technical Reports Server (NTRS)

Kratz, Jonathan L.; Chapman, Jeffryes W.; Guo, Ten-Huei

2017-01-01

The efficiency of aircraft gas turbine engines is sensitive to the distance between the tips of its turbine blades and its shroud, which serves as its containment structure. Maintaining tighter clearance between these components has been shown to increase turbine efficiency, increase fuel efficiency, and reduce the turbine inlet temperature, and this correlates to a longer time-on-wing for the engine. Therefore, there is a desire to maintain a tight clearance in the turbine, which requires fast response active clearance control. Fast response active tip clearance control will require an actuator to modify the physical or effective tip clearance in the turbine. This paper evaluates the requirements of a generic active turbine tip clearance actuator for a modern commercial aircraft engine using the Commercial Modular Aero-Propulsion System Simulation 40k (C-MAPSS40k) software that has previously been integrated with a dynamic tip clearance model. A parametric study was performed in an attempt to evaluate requirements for control actuators in terms of bandwidth, rate limits, saturation limits, and deadband. Constraints on the weight of the actuation system and some considerations as to the force which the actuator must be capable of exerting and maintaining are also investigated. From the results, the relevant range of the evaluated actuator parameters can be extracted. Some additional discussion is provided on the challenges posed by the tip clearance control problem and the implications for future small core aircraft engines.

Intravascular US-Guided Portal Vein Access: Improved Procedural Metrics during TIPS Creation.

PubMed

Gipson, Matthew G; Smith, Mitchell T; Durham, Janette D; Brown, Anthony; Johnson, Thor; Ray, Charles E; Gupta, Rajan K; Kondo, Kimi L; Rochon, Paul J; Ryu, Robert K

2016-08-01

To evaluate transjugular intrahepatic portosystemic shunt (TIPS) outcomes and procedure metrics with the use of three different image guidance techniques for portal vein (PV) access during TIPS creation. A retrospective review of consecutive patients who underwent TIPS procedures for a range of indications during a 28-month study period identified a population of 68 patients. This was stratified by PV access techniques: fluoroscopic guidance with or without portography (n = 26), PV marker wire guidance (n = 18), or intravascular ultrasound (US) guidance (n = 24). Procedural outcomes and procedural metrics, including radiation exposure, contrast agent volume used, procedure duration, and PV access time, were analyzed. No differences in demographic or procedural characteristics were found among the three groups. Technical success, technical success of the primary planned approach, hemodynamic success, portosystemic gradient, and procedure-related complications were not significantly different among groups. Fluoroscopy time (P = .003), air kerma (P = .01), contrast agent volume (P = .003), and total procedural time (P = .02) were reduced with intravascular US guidance compared with fluoroscopic guidance. Fluoroscopy time (P = .01) and contrast agent volume (P = .02) were reduced with intravascular US guidance compared with marker wire guidance. Intravascular US guidance of PV access during TIPS creation not only facilitates successful TIPS creation in patients with challenging anatomy, as suggested by previous investigations, but also reduces important procedure metrics including radiation exposure, contrast agent volume, and overall procedure duration compared with fluoroscopically guided TIPS creation. Copyright © 2016 SIR. Published by Elsevier Inc. All rights reserved.

Image simulation and surface reconstruction of undercut features in atomic force microscopy

NASA Astrophysics Data System (ADS)

Qian, Xiaoping; Villarrubia, John; Tian, Fenglei; Dixson, Ronald

2007-03-01

CD-AFMs (critical dimension atomic force microscopes) are instruments with servo-control of the tip in more than one direction. With appropriately "boot-shaped" or flared tips, such instruments can image vertical or even undercut features. As with any AFM, the image is a dilation of the sample shape with the tip shape. Accurate extraction of the CD requires a correction for the tip effect. Analytical methods to correct images for the tip shape have been available for some time for the traditional (vertical feedback only) AFMs, but were until recently unavailable for instruments with multi-dimensional feedback. Dahlen et al. [J. Vac. Sci. Technol. B23, pp. 2297-2303, (2005)] recently introduced a swept-volume approach, implemented for 2-dimensional (2D) feedback. It permits image simulation and sample reconstruction, techniques previously developed for the traditional instruments, to be extended for the newer tools. We have introduced [X. Qian and J. S. Villarrubia, Ultramicroscopy, in press] an alternative dexel-based method, that does the same in either 2D or 3D. This paper describes the application of this method to sample shapes of interest in semiconductor manufacturing. When the tip shape is known (e.g., by prior measurement using a tip characterizer) a 3D sample surface may be reconstructed from its 3D image. Basing the CD measurement upon such a reconstruction is shown here to remove some measurement artifacts that are not removed (or are incompletely removed) by the existing measurement procedures.

NMR identification of the binding surfaces involved in the Salmonella and Shigella Type III secretion tip-translocon protein-protein interactions.

PubMed

McShan, Andrew C; Kaur, Kawaljit; Chatterjee, Srirupa; Knight, Kevin M; De Guzman, Roberto N

2016-08-01

The type III secretion system (T3SS) is essential for the pathogenesis of many bacteria including Salmonella and Shigella, which together are responsible for millions of deaths worldwide each year. The structural component of the T3SS consists of the needle apparatus, which is assembled in part by the protein-protein interaction between the tip and the translocon. The atomic detail of the interaction between the tip and the translocon proteins is currently unknown. Here, we used NMR methods to identify that the N-terminal domain of the Salmonella SipB translocon protein interacts with the SipD tip protein at a surface at the distal region of the tip formed by the mixed α/β domain and a portion of its coiled-coil domain. Likewise, the Shigella IpaB translocon protein and the IpaD tip protein interact with each other using similar surfaces identified for the Salmonella homologs. Furthermore, removal of the extreme N-terminal residues of the translocon protein, previously thought to be important for the interaction, had little change on the binding surface. Finally, mutations at the binding surface of SipD reduced invasion of Salmonella into human intestinal epithelial cells. Together, these results reveal the binding surfaces involved in the tip-translocon protein-protein interaction and advance our understanding of the assembly of the T3SS needle apparatus. Proteins 2016; 84:1097-1107. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Fiber optic muzzle brake tip for reducing fiber burnback and stone retropulsion during thulium fiber laser lithotripsy.

PubMed

Hutchens, Thomas C; Gonzalez, David A; Irby, Pierce B; Fried, Nathaniel M

2017-01-01

The experimental thulium fiber laser (TFL) is being explored as an alternative to the current clinical gold standard Holmium:YAG laser for lithotripsy. The near single-mode TFL beam allows coupling of higher power into smaller optical fibers than the multimode Holmium laser beam profile, without proximal fiber tip degradation. A smaller fiber is desirable because it provides more space in the ureteroscope working channel for increased saline irrigation rates and allows maximum ureteroscope deflection. However, distal fiber tip burnback increases as fiber diameter decreases. Previous studies utilizing hollow steel sheaths around recessed distal fiber tips reduced fiber burnback but increased stone retropulsion. A “fiber muzzle brake” was tested for reducing both fiber burnback and stone retropulsion by manipulating vapor bubble expansion. TFL lithotripsy studies were performed at 1908 nm, 35 mJ, 500 ?? ? s , and 300 Hz using a 100 - ? m -core fiber. The optimal stainless steel muzzle brake tip tested consisted of a 1-cm-long, 560 - ? m -outer-diameter, 360 - ? m -inner-diameter tube with a 275 - ? m -diameter through hole located 250 ?? ? m from the distal end. The fiber tip was recessed a distance of 500 ?? ? m . Stone phantom retropulsion, fiber tip burnback, and calcium oxalate stone ablation studies were performed ex vivo. Small stones with a mass of 40 ± 4 ?? mg and 4-mm-diameter were ablated over a 1.5-mm sieve in 25 ± 4 ?? s

Optimisation of readout performance of phase-change probe memory in terms of capping layer and probe tip

NASA Astrophysics Data System (ADS)

Wang, Lei; Wright, C. David; Aziz, Mustafa. M.; Yang, Ci Hui; Yang, Guo Wei

2014-11-01

The capping layer and the probe tip that serve as the protective layer and the recording tool, respectively, for phase-change probe memory play an important role on the writing performance of phase-change probe memory, thus receiving considerable attention. On the other hand, their influence on the readout performance of phasechange probe memory has rarely been reported before. A three-dimensional parametric study based on the Laplace equation was therefore conducted to investigate the effect of the capping layer and the probe tip on the resulting reading contrast for the two cases of reading a crystalline bit from an amorphous matrix and reading an amorphous bit from a crystalline matrix. The results indicated that a capping layer with a thickness of 2 nm and an electrical conductivity of 50 Ω-1m-1 is able to provide an appropriate reading contrast for both the cases, while satisfying the previous writing requirement, particularly with the assistance of a platinum silicide probe tip.

Blade tip, finite aspect ratio, and dynamic stall effects on the Darrieus rotor

NASA Astrophysics Data System (ADS)

Paraschivoiu, I.; Desy, P.; Masson, C.

1988-02-01

The objective of the work described in this paper was to apply the Boeing-Vertol dynamic stall model in an asymmetric manner to account for the asymmetry of the flow between the left and right sides of the rotor. This phenomenon has been observed by the flow visualization of a two-straight-bladed Darrieus rotor in the IMST water tunnel. Also introduced into the aerodynamic model are the effects of the blade tip and finite aspect ratio on the aerodynamic performance of the Darrieus wind turbine. These improvements are compatible with the double-multiple-streamtube model and have been included in the CARDAAV computer code for predicting the aerodynamic performance. Very good agreement has been observed between the test data (Sandia 17 m) and theoretical predictions; a significant improvement over the previous dynamic stall model was obtained for the rotor power at low tip speed ratios, while the inclusion of the finite aspect ratio effects enhances the prediction of the rotor power for high tip speed ratios. The tip losses and finite aspect ratio effects were also calculated for a small-scale vertical-axis wind turbine, with a two-straight-bladed (NACA 0015) rotor.

Investigation of Unsteady Flow Field in a Low-Speed One and a Half Stage Axial Compressor. Part 2; Effects of Tip Gap Size On the Tip Clearance Flow Structure at Near Stall Operation

NASA Technical Reports Server (NTRS)

Hah, Chunill; Hathaway, Michael; Katz, Joseph

2014-01-01

The primary focus of this paper is to investigate the effect of rotor tip gap size on how the rotor unsteady tip clearance flow structure changes in a low speed one and half stage axial compressor at near stall operation (for example, where maximum pressure rise is obtained). A Large Eddy Simulation (LES) is applied to calculate the unsteady flow field at this flow condition with both a small and a large tip gaps. The numerically obtained flow fields at the small clearance matches fairly well with the available initial measurements obtained at the Johns Hopkins University with 3-D unsteady PIV in an index-matched test facility which renders the compressor blades and casing optically transparent. With this setup, the unsteady velocity field in the entire flow domain, including the flow inside the tip gap, can be measured. The numerical results are also compared with previously published measurements in a low speed single stage compressor (Maerz et al. [2002]). The current study shows that, with the smaller rotor tip gap, the tip clearance vortex moves to the leading edge plane at near stall operating condition, creating a nearly circumferentially aligned vortex that persists around the entire rotor. On the other hand, with a large tip gap, the clearance vortex stays inside the blade passage at near stall operation. With the large tip gap, flow instability and related large pressure fluctuation at the leading edge are observed in this one and a half stage compressor. Detailed examination of the unsteady flow structure in this compressor stage reveals that the flow instability is due to shed vortices near the leading edge, and not due to a three-dimensional separation vortex originating from the suction side of the blade, which is commonly referred to during a spike-type stall inception. The entire tip clearance flow is highly unsteady. Many vortex structures in the tip clearance flow, including the sheet vortex system near the casing, interact with each other. The core tip clearance vortex, which is formed with the rotor tip gap flows near the leading edge, is also highly unsteady or intermittent due to pressure oscillations near the leading edge and varies from passage to passage. For the current compressor stage, the evidence does not seem to support that a classical vortex breakup occurs in any organized way, even with the large tip gap. Although wakes from the IGV influence the tip clearance flow in the rotor, the major characteristics of rotor tip clearance flows in isolated or single stage rotors are observed in this one and a half stage axial compressor.

Dual Check Valve and Method of Controlling Flow Through the Same

NASA Technical Reports Server (NTRS)

Corallo, Roger (Inventor)

2016-01-01

A dual check valve includes, a housing having a cavity fluidically connecting three ports, a movable member movably engaged within the cavity from at least a first position occluding a first port of the three ports, a second position occluding a second port of the three ports, and a third position allowing flow between both the first port, the second port and a third port of the three ports.

Figure ground segregation modulates perceived direction of ambiguous moving gratings and plaids.

PubMed

Tommasi, L; Vallortigara, G

1999-02-01

A translating oriented grating viewed through a circular aperture with an occluding area in the middle appeared to move alternately in an oblique or in a vertical direction depending on the foreground/background assignment on the central occluding area. The effect occurred even when the central area was simply removed from the display, thus giving rise to a 'subjective' occluder. Parametric studies revealed that the probability of seeing oblique or vertical motion was affected by the size of the central area but not by its contrast relationships with the grating. Similar phenomena of ambiguous motion direction were observed using changes in colour along a translating grating that produced neon colour spreading effects, or using oriented edge discontinuities that collapsed into subjective plaids composed of two one-dimensional gratings. These results are discussed with respect to the hypothesis that surface segmentation mechanisms play a crucial part in the interpretation of motion signals.

Externalized decondensed neutrophil chromatin occludes pancreatic ducts and drives pancreatitis

PubMed Central

Leppkes, Moritz; Maueröder, Christian; Hirth, Sebastian; Nowecki, Stefanie; Günther, Claudia; Billmeier, Ulrike; Paulus, Susanne; Biermann, Mona; Munoz, Luis E.; Hoffmann, Markus; Wildner, Dane; Croxford, Andrew L.; Waisman, Ari; Mowen, Kerri; Jenne, Dieter E.; Krenn, Veit; Mayerle, Julia; Lerch, Markus M.; Schett, Georg; Wirtz, Stefan; Neurath, Markus F.; Herrmann, Martin; Becker, Christoph

2016-01-01

Ductal occlusion has been postulated to precipitate focal pancreatic inflammation, while the nature of the primary occluding agents has remained elusive. Neutrophils make use of histone citrullination by peptidyl arginine deiminase-4 (PADI4) in contact to particulate agents to extrude decondensed chromatin as neutrophil extracellular traps (NETs). In high cellular density, NETs form macroscopically visible aggregates. Here we show that such aggregates form inside pancreatic ducts in humans and mice occluding pancreatic ducts and thereby driving pancreatic inflammation. Experimental models indicate that PADI4 is critical for intraductal aggregate formation and that PADI4-deficiency abrogates disease progression. Mechanistically, we identify the pancreatic juice as a strong instigator of neutrophil chromatin extrusion. Characteristic single components of pancreatic juice, such as bicarbonate ions and calcium carbonate crystals, induce aggregated NET formation. Ductal occlusion by aggregated NETs emerges as a pathomechanism with relevance in a plethora of inflammatory conditions involving secretory ducts. PMID:26964500

Modeling time-dependent corrosion fatigue crack propagation in 7000 series aluminum alloys

NASA Technical Reports Server (NTRS)

Mason, Mark E.; Gangloff, Richard P.

1994-01-01

Stress corrosion cracking and corrosion fatigue experiments were conducted with the susceptible S-L orientation of AA7075-T651, immersed in acidified and inhibited NaCl solution, to provide a basis for incorporating environmental effects into fatigue crack propagation life prediction codes such as NASA FLAGRO. This environment enhances da/dN by five to ten-fold compared to fatigue in moist air. Time-based crack growth rates from quasi-static load experiments are an order of magnitude too small for accurate linear superposition prediction of da/dN for loading frequencies above 0.001 Hz. Alternate methods of establishing da/dt, based on rising-load or ripple-load-enhanced crack tip strain rate, do not increase da/dt and do not improve linear superposition. Corrosion fatigue is characterized by two regimes of frequency dependence; da/dN is proportional to f(exp -1) below 0.001 Hz and to F(exp 0) to F(exp -0.1) for higher frequencies. Da/dN increases mildly both with increasing hold-time at K(sub max) and with increasing rise-time for a range of loading waveforms. The mild time-dependence is due to cycle-time-dependent corrosion fatigue growth. This behavior is identical for S-L nd L-T crack orientations. The frequency response of environmental fatigue in several 7000 series alloys is variable and depends on undefined compositional or microstructural variables. Speculative explanations are based on the effect of Mg on occluded crack chemistry and embritting hydrogen uptake, or on variable hydrogen diffusion in the crack tip process zone. Cracking in the 7075/NaCl system is adequately described for life prediction by linear superposition for prolonged load-cycle periods, and by a time-dependent upper bound relationship between da/dN and delta K for moderate loading times.

An integrated approach to endoscopic instrument tracking for augmented reality applications in surgical simulation training.

PubMed

Loukas, Constantinos; Lahanas, Vasileios; Georgiou, Evangelos

2013-12-01

Despite the popular use of virtual and physical reality simulators in laparoscopic training, the educational potential of augmented reality (AR) has not received much attention. A major challenge is the robust tracking and three-dimensional (3D) pose estimation of the endoscopic instrument, which are essential for achieving interaction with the virtual world and for realistic rendering when the virtual scene is occluded by the instrument. In this paper we propose a method that addresses these issues, based solely on visual information obtained from the endoscopic camera. Two different tracking algorithms are combined for estimating the 3D pose of the surgical instrument with respect to the camera. The first tracker creates an adaptive model of a colour strip attached to the distal part of the tool (close to the tip). The second algorithm tracks the endoscopic shaft, using a combined Hough-Kalman approach. The 3D pose is estimated with perspective geometry, using appropriate measurements extracted by the two trackers. The method has been validated on several complex image sequences for its tracking efficiency, pose estimation accuracy and applicability in AR-based training. Using a standard endoscopic camera, the absolute average error of the tip position was 2.5 mm for working distances commonly found in laparoscopic training. The average error of the instrument's angle with respect to the camera plane was approximately 2°. The results are also supplemented by video segments of laparoscopic training tasks performed in a physical and an AR environment. The experiments yielded promising results regarding the potential of applying AR technologies for laparoscopic skills training, based on a computer vision framework. The issue of occlusion handling was adequately addressed. The estimated trajectory of the instruments may also be used for surgical gesture interpretation and assessment. Copyright © 2013 John Wiley & Sons, Ltd.

Involvement of the cGMP pathway in the osthole-facilitated glutamate release in rat hippocampal nerve endings.

PubMed

Lin, Tzu Yu; Lu, Cheng Wei; Huang, Wei-Jan; Wang, Su-Jane

2012-03-01

Osthole, an active constituent isolated from Cnidium monnieri (L.) Cusson, has previously been shown to have the capacity to increase depolarization-evoked glutamate release in rat hippocampal nerve terminals. As cGMP-dependent signaling cascade has been found to modulate glutamate release at the presynaptic level, the aim of this study was to further examine the role of cGMP signaling pathway in the regulation of osthole on glutamate release in hippocampal synaptosomes. Results showed that osthole dose-dependently increased intrasynaptosomal cGMP levels. The elevation of cGMP levels by osthole was prevented by the phosphodiesterase 5 inhibitor sildenafil but was insensitive to the guanylyl cyclase inhibitor ODQ. In addition, osthole-induced facilitation of 4-aminopyridine (4-AP)-evoked glutamate release was completely prevented by the cGMP-dependent protein kinase (PKG) inhibitors, KT5823, and Rp-8-Br-PET-cGMPS. Direct activation of PKG with 8-Br-cGMP or 8-pCPT-cGMP also occluded the osthole-mediated facilitation of 4-AP-evoked glutamate release. Furthermore, sildenafil exhibited a dose-dependent facilitation of 4-AP-evoked release of glutamate and occluded the effect of osthole on the 4-AP-evoked glutamate release. Collectively, our findings suggest that osthole-mediated facilitation of glutamate release involves the activation of cGMP/PKG-dependent pathway. Copyright © 2011 Wiley Periodicals, Inc.

Iconicity influences how effectively minimally verbal children with autism and ability-matched typically developing children use pictures as symbols in a search task.

PubMed

Hartley, Calum; Allen, Melissa L

2015-07-01

Previous word learning studies suggest that children with autism spectrum disorder may have difficulty understanding pictorial symbols. Here we investigate the ability of children with autism spectrum disorder and language-matched typically developing children to contextualize symbolic information communicated by pictures in a search task that did not involve word learning. Out of the participant's view, a small toy was concealed underneath one of four unique occluders that were individuated by familiar nameable objects or unfamiliar unnamable objects. Children were shown a picture of the hiding location and then searched for the toy. Over three sessions, children completed trials with color photographs, black-and-white line drawings, and abstract color pictures. The results reveal zero group differences; neither children with autism spectrum disorder nor typically developing children were influenced by occluder familiarity, and both groups' errorless retrieval rates were above-chance with all three picture types. However, both groups made significantly more errorless retrievals in the most-iconic photograph trials, and performance was universally predicted by receptive language. Therefore, our findings indicate that children with autism spectrum disorder and young typically developing children can contextualize pictures and use them to adaptively guide their behavior in real time and space. However, this ability is significantly influenced by receptive language development and pictorial iconicity. © The Author(s) 2014.

Advanced spatiotemporal mapping methods give new insights into the coordination of contractile activity in the stomach of the rat.

PubMed

Lentle, R G; Reynolds, G W; Hulls, C M; Chambers, J P

2016-12-01

We used spatiotemporal mapping of strain rate to determine the direction of propagation and amplitudes of the longitudinal and circumferential components of antrocorporal (AC) contractions and fundal contractions in the rat stomach maintained ex vivo and containing a volume of fluid that was within its normal functional capacity. In the region of the greater curvature the longitudinal and circular components of AC contractions propagated synchronously at right angles to the arciform geometric axis of the stomach. However, the configuration of AC contractions was U shaped, neither the circular nor the longitudinal component of contractions being evident in the upper proximal corpus. Similarly, in the distal upper antrum of some preparations, circumferential components propagated more rapidly than longitudinal components. Ongoing "high-frequency, low-amplitude myogenic contractions" were identified in the upper proximal gastric corpus and on the anterior and posterior wall of the fundus. The amplitudes of these contractions were modulated in the occluded stomach by low-frequency pressure waves that occurred spontaneously. Hence the characteristics of phasic contractions vary regionally in the antrum and corpus and a previously undescribed high-frequency contractile component was identified in the proximal corpus and fundus, the latter being modulated in synchrony with cyclic variation in intrafundal pressure in the occluded fundus. Copyright © 2016 the American Physiological Society.

The tip-link antigen, a protein associated with the transduction complex of sensory hair cells, is protocadherin-15.

PubMed

Ahmed, Zubair M; Goodyear, Richard; Riazuddin, Saima; Lagziel, Ayala; Legan, P Kevin; Behra, Martine; Burgess, Shawn M; Lilley, Kathryn S; Wilcox, Edward R; Riazuddin, Sheikh; Griffith, Andrew J; Frolenkov, Gregory I; Belyantseva, Inna A; Richardson, Guy P; Friedman, Thomas B

2006-06-28

Sound and acceleration are detected by hair bundles, mechanosensory structures located at the apical pole of hair cells in the inner ear. The different elements of the hair bundle, the stereocilia and a kinocilium, are interconnected by a variety of link types. One of these links, the tip link, connects the top of a shorter stereocilium with the lateral membrane of an adjacent taller stereocilium and may gate the mechanotransducer channel of the hair cell. Mass spectrometric and Western blot analyses identify the tip-link antigen, a hitherto unidentified antigen specifically associated with the tip and kinocilial links of sensory hair bundles in the inner ear and the ciliary calyx of photoreceptors in the eye, as an avian ortholog of human protocadherin-15, a product of the gene for the deaf/blindness Usher syndrome type 1F/DFNB23 locus. Multiple protocadherin-15 transcripts are shown to be expressed in the mouse inner ear, and these define four major isoform classes, two with entirely novel, previously unidentified cytoplasmic domains. Antibodies to the three cytoplasmic domain-containing isoform classes reveal that each has a different spatiotemporal expression pattern in the developing and mature inner ear. Two isoforms are distributed in a manner compatible for association with the tip-link complex. An isoform located at the tips of stereocilia is sensitive to calcium chelation and proteolysis with subtilisin and reappears at the tips of stereocilia as transduction recovers after the removal of calcium chelators. Protocadherin-15 is therefore associated with the tip-link complex and may be an integral component of this structure and/or required for its formation.

Magnetic energy flow imaging of magnetic recording head with enhanced resolution and sensitivity by A-MFM using high magnetic moment superparamagnetic tip

NASA Astrophysics Data System (ADS)

Kumar, Pawan; Cao, Yongze; Suzuki, Yudai; Yoshimura, Satoru; Saito, Hitoshi

2018-06-01

In this report, the magnetic energy flow of AC magnetic field is imaged from a perpendicular magnetic recording head by alternating magnetic force microscopy (A-MFM) with high magnetic moment Co0.43(GdOx)0.57 superparamagnetic (SP) tip. The present magnetic energy flow imaging phenomenon is able to detect the flow direction of AC magnetic field energy from the recording head. A simple model for the flow direction of the AC magnetic energy is given and revealed that when the AC magnetic field energy from the surface of main pole increases, the energy from the side cross section decreases due to the periodical change of magnetization direction at the main pole area. The A-MFM magnetic energy imaging performance by 100 nm Co0.43(GdOx)0.57 SP tip is compared with the magnetic field imaging with the 25 nm Co0.80Zr0.05Nb0.15 soft magnetic (SM) tip. The spatial resolution measured by Fourier analysis for Co0.43(GdOx)0.57 SP tip is enhanced dramatically to ˜10 nm with low thermal noise, as compared to ˜13 nm by Co0.80Zr0.05Nb0.15 SM tip as well as the previously reported MFM tip. Moreover, the sensitivity and resolution are investigated for a range of head current to confirm the suitability of the magnetic energy flow imaging by Co0.43(GdOx)0.57 SP tip to low as well as high magnetic field source. Further, the A-MFM measurements are performed with the 100 nm Au coated conducting tip to investigate the possibility of electrostatic contribution in magnetic energy imaging by Co0.43(GdOx)0.57 SP tip and revealed that the present A-MFM measurement is free from any electrostatic artifacts. The present magnetic energy flow imaging phenomena with the high magnetic moment Co0.43(GdOx)0.57 SP tip provides an avenue for the analysis of the magnetic field energy component from the head field profile.

An Experimental Investigation of the Functional Hypothesis and Evolutionary Advantage of Stone-Tipped Spears

PubMed Central

Wilkins, Jayne; Schoville, Benjamin J.; Brown, Kyle S.

2014-01-01

Stone-tipped weapons were a significant innovation for Middle Pleistocene hominins. Hafted hunting technology represents the development of new cognitive and social learning mechanisms within the genus Homo, and may have provided a foraging advantage over simpler forms of hunting technology, such as a sharpened wooden spear. However, the nature of this foraging advantage has not been confirmed. Experimental studies and ethnographic reports provide conflicting results regarding the relative importance of the functional, economic, and social roles of hafted hunting technology. The controlled experiment reported here was designed to test the functional hypothesis for stone-tipped weapons using spears and ballistics gelatin. It differs from previous investigations of this type because it includes a quantitative analysis of wound track profiles and focuses specifically on hand-delivered spear technology. Our results do not support the hypothesis that tipped spears penetrate deeper than untipped spears. However, tipped spears create a significantly larger inner wound cavity that widens distally. This inner wound cavity is analogous to the permanent wound cavity in ballistics research, which is considered the key variable affecting the relative ‘stopping power’ or ‘killing power’ of a penetrating weapon. Tipped spears conferred a functional advantage to Middle Pleistocene hominins, potentially affecting the frequency and regularity of hunting success with important implications for human adaptation and life history. PMID:25162397

Reaching More Students Through Thinking in Physics

NASA Astrophysics Data System (ADS)

Coletta, Vincent P.

2017-02-01

Thinking in Physics (TIP) is a new curriculum that is more effective than commonly used interactive engagement methods for students who have the greatest difficulty learning physics. Research has shown a correlation between learning in physics and other factors, including scientific reasoning ability. The TIP curriculum addresses those factors. Features of the curriculum and evidence of its effectiveness are described. The most recent version of the TIP curriculum has greatly reduced a substantial gender gap that previously existed. More details and sample materials are provided in Thinking in Physics, a book intended for instructors of introductory physics, published in 2014 by Pearson as part of its Educational Innovation series. Additional materials, both for students and instructors, are provided on the website http://thinkinginphysics.com. Both the book and the website are free.

The 30-kW ammonia arcjet technology

NASA Technical Reports Server (NTRS)

Deininger, W. D.; Chopra, A.; Pivirotto, T. J.; Goodfellow, K. D.; Barnett, J. W.

1990-01-01

The technical results are summarized of a 30 kW class ammonia propellant arcjet technology program. Evaluation of previous arcjet thruster performance, including materials analysis of used thruster components, led to the design of an arcjet with improved performance and thermal characteristics. Tests of the new engine demonstrated that engine performance is relatively insensitive to cathode tip geometry. Other data suggested a maximum sustainable arc length for a given thruster configuration, beyond which the arc may reconfigure in a destructive manner. A flow controller calibration error was identified. This error caused previously reported values of specific impulse and thrust efficiency to be 20 percent higher than the real values. Corrected arcjet performance data are given. Duration tests of 413 and 252 hours, and several tests 100 hours in duration, were performed. The cathode tip erosion rate increased with increasing arc current. Elimination of power source ripple did not affect cathode tip whisker growth. Results of arcjet modeling, diagnostic development and mission analyses are also discussed. The 30 kW ammonia arcjet may now be considered ready for development for a flight demonstration, but widespread application of 30 kW class arcjet will require improved efficiency and lifetime.

Three major nucleolar proteins migrate from nucleolus to nucleoplasm and cytoplasm in root tip cells of Vicia faba L. exposed to aluminum.

PubMed

Qin, Rong; Zhang, Huaning; Li, Shaoshan; Jiang, Wusheng; Liu, Donghua

2014-09-01

Results from our previous investigation indicated that Al could affect the nucleolus and induce extrusion of silver-staining nucleolar particles containing argyrophilic proteins from the nucleolus into the cytoplasm in root tip cells of Vicia faba L. So far, the nucleolar proteins involved have not been identified. It is well known that nucleophosmin (B23), nucleolin (C23), and fibrillarin are three major and multifunctional nucleolar proteins. Therefore, effects of Al on B23, C23, and fibrillarin in root tip cells of V. faba exposed to 100 μM Al for 48 h were observed and analyzed using indirect immunofluorescence microscopy and Western blotting. The results from this work demonstrated that after 100 μM of Al treatment for 48 h, B23 and C23 migrated from the nucleolus to the cytoplasm and fibrillarin from the nucleolus to the nucleoplasm. In some cells, fibrillarin was present only in the cytoplasm. Western blotting data revealed higher expression of the three major nucleolar proteins in Al-treated roots compared with the control and that the B23 content increased markedly. These findings confirmed our previous observations.

On the Importance of Spatial Resolution for Flap Side Edge Noise Prediction

NASA Technical Reports Server (NTRS)

Mineck, Raymond E.; Khorrami, Mehdi R.

2017-01-01

A spatial resolution study of flap tip flow and the effects on the farfield noise signature for an 18%-scale, semispan Gulfstream aircraft model are presented. The NASA FUN3D unstructured, compressible Navier-Stokes solver was used to perform the highly resolved, time-dependent, detached eddy simulations of the flow field associated with the flap for this high-fidelity aircraft model. Following our previous work on the same model, the latest computations were undertaken to determine the causes of deficiencies observed in our earlier predictions of the steady and unsteady surface pressures and off-surface flow field at the flap tip regions, in particular the outboard tip area, where the presence of a cavity at the side-edge produces very complex flow features and interactions. The present results show gradual improvement in steady loading at the outboard flap edge region with increasing spatial resolution, yielding more accurate fluctuating surface pressures, off-surface flow field, and farfield noise with improved high-frequency content when compared with wind tunnel measurements. The spatial resolution trends observed in the present study demonstrate that the deficiencies reported in our previous computations are mostly caused by inadequate spatial resolution and are not related to the turbulence model.

An Experimental Characterization of Tip Leakage Flows and Corresponding Effects on Multistage Compressor Performance

NASA Astrophysics Data System (ADS)

Berdanier, Reid Adam

The effect of rotor tip clearances in turbomachinery applications has been a primary research interest for nearly 80 years. Over that time, studies have shown increased tip clearance in axial flow compressors typically has a detrimental effect on overall pressure rise capability, isentropic efficiency, and stall margin. With modern engine designs trending toward decreased core sizes to increase propulsive efficiency (by increasing bypass ratio) or additional compression stages to increase thermal efficiency by increasing the overall pressure ratio, blade heights in the rear stages of the high pressure compressor are expected to decrease. These rear stages typically feature smaller blade aspect ratios, for which endwall flows are more important, and the rotor tip clearance height represents a larger fraction of blade span. As a result, data sets collected with large relative rotor tip clearance heights are necessary to facilitate these future small core design goals. This research seeks to characterize rotor tip leakage flows for three tip clearance heights in the Purdue three-stage axial compressor facility (1.5%, 3.0%, and 4.0% as a percentage of overall annulus height). The multistage environment of this compressor provides the unique opportunity to examine tip leakage flow effects due to stage matching, stator-rotor interactions, and rotor-rotor interactions. The important tip leakage flow effects which develop as a result of these interactions are absent for previous studies which have been conducted using single-stage machines or isolated rotors. A series of compressor performance maps comprise points at four corrected speeds for each of the three rotor tip clearance heights. Steady total pressure and total temperature measurements highlight the effects of tip leakage flows on radial profiles and wake shapes throughout the compressor. These data also evaluate tip clearance effects on efficiency, stall margin, and peak pressure rise capability. An emphasis of measurements collected at these part-speed and off-design conditions provides a unique data set for calibrating computational models and predictive algorithms. Further investigations with detailed steady total pressure traverses provide additional insight to tip leakage flow effects on stator performance. A series of data on the 100% corrected speedline further characterize the tip leakage flow using time-resolved measurements from a combination of instrumentation techniques. An array of high-frequency-response piezoresistive pressure transducers installed over the rotors allows quantification of tip leakage flow trajectories. These data, along with measurements from a fast-response total pressure probe downstream of the rotors, evaluate the development of tip leakage flows and assess the corresponding effects of upstream stator wakes. Finally, thermal anemometry measurements collected using the single slanted hot-wire technique evaluate three-dimensional velocity components throughout the compressor. These data facilitate calculations of several flow metrics, including a blockage parameter and phase-locked streamwise vorticity.

Indocyanine green videoangiography (ICGV)-guided surgery of parasagittal meningiomas occluding the superior sagittal sinus (SSS).

PubMed

d'Avella, Elena; Volpin, Francesco; Manara, Renzo; Scienza, Renato; Della Puppa, Alessandro

2013-03-01

Maximal safe resection is the goal of correct surgical treatment of parasagittal meningiomas, and it is intimately related to the venous anatomy both near and directly involved by the tumor. Indocyanine green videoangiography (ICGV) has already been advocated as an intra-operative resourceful technique in brain tumor surgery for the identification of vessels. The aim of this study was to investigate the role of ICGV in surgery of parasagittal meningiomas occluding the superior sagittal sinus (SSS). In this study, we prospectively analyzed clinical, radiological and intra-operative findings of patients affected by parasagittal meningioma occluding the SSS, who underwent ICGV assisted-surgery. Radiological diagnosis of complete SSS occlusion was pre-operatively established in all cases. ICGV was performed before dural opening, before and during tumor resection, at the end of the procedure. Five patients were included in our study. In all cases, ICGV guided dural opening, tumor resection, and venous management. The venous collateral pathway was easily identified and preserved in all cases. Radical resection was achieved in four cases. Surgery was uneventful in all cases. Despite the small number of patients, our study shows that ICG videoangiography could play a crucial role in guiding surgery of parasagittal meningioma occluding the SSS. Further studies are needed to define the role of this technique on functional and oncological outcome of these patients.

A new coated nitinol occluder for transcatheter closure of ventricular septal defects in a canine model.

PubMed

Zhou, Yong; Chen, Feng; Huang, Xinmiao; Zhao, Xianxian; Wu, Hong; Bai, Yuan; Qin, Yongwen

2013-01-01

This study evaluated feasibility and safety of implanting the polyester-coated nitinol ventricular septal defect occluder (pcVSDO) in the canine model. VSD models were successfully established by transseptal ventricular septal puncture via the right jugular vein in 15 out of 18 canines. Two types of VSDOs were implanted, either with pcVSDOs (n = 8) as the new type occluder group or with the commercial ventricular septal defect occluders (VSDOs, n = 7, Shanghai Sharp Memory Alloy Co. Ltd.) as the control group. Sheath size was 10 French (10 Fr) in two groups. Then the general state of the canines was observed after implantation. ECG and TTE were performed, respectively, at 7, 30, 90 days of follow-up. The canines were sacrificed at these time points for pathological and scanning electron microscopy examination. The devices were successfully implanted in all 15 canines and were retrievable and repositionable. There was no thrombus formation on the device or occurrence of complete heart block. The pcVSDO surface implanted at day 7 was already covered with neotissue by gross examination, and it completed endothelialization at day 30, while the commercial VSDO was covered with the neotissue in 30th day and the complete endothelialization in 90th day. The study shows that pcVSDO is feasible and safe to close canine VSD model and has good biocompatibility and shorter time of endothelialization.

Angle-closure glaucoma in an urban population in southern India. The Andhra Pradesh eye disease study.

PubMed

Dandona, L; Dandona, R; Mandal, P; Srinivas, M; John, R K; McCarty, C A; Rao, G N

2000-09-01

To assess the prevalence and features of angle-closure glaucoma (ACG) in an urban population in southern India. A population-based, cross-sectional study. A total of 2522 (85.4% of those eligible) persons of all ages, including 1399 persons 30 years of age or older, from 24 clusters representative of the population of Hyderabad city. The participants underwent an interview and detailed eye examination that included logarithm of minimum angle of resolution visual acuity, refraction, slit-lamp biomicroscopy, applanation tonometry, and gonioscopy; pupil dilatation and stereoscopic fundus evaluation was performed if the risk of angle-closure as a result of dilatation was not believed to be imminent. Humphrey threshold 24-2 visual fields (Humphrey Instruments Inc., San Leandro, CA) were performed when indicated by standardized criteria for disc damage or if intraocular pressure (IOP) was 22 mmHg or more. An occludable angle was defined as pigmented posterior trabecular meshwork not visible by gonioscopy in three quarters or more of the angle circumference. Manifest primary angle-closure glaucoma (PACG) was defined as IOP of 22 mmHg or more or glaucomatous optic disc damage with visual field loss in the presence of an occludable angle. An IOP of 22 mmHg or more or glaucomatous optic disc damage in the presence of an occludable angle secondary to an obvious cause was defined as secondary ACG. Manifest PACG and occludable angles without ACG were present in 12 and 24 participants, respectively, with age- and gender-adjusted prevalence (95% confidence interval [CI]) of 0.71% (0.34%-1.31%) and 1.41% (0.73%-2.09%) in participants 30 years of age or older, and 1.08% (0.36%-1.80%) and 2.21% (1.15%-3.27%) in participants 40 years of age or older, respectively. With multivariate analysis, the prevalence of these two conditions considered together increased significantly with age (P < 0.001); although not statistically significant, these were more common in females (odds ratio 1.70; 95% CI, 0.82-3.54) and in those belonging to lower socioeconomic strata as compared with middle and upper strata (odds ratio, 1.82; 95% CI, 0.88-3.74). The odds of manifest PACG were higher in the presence of hyperopia of more than 2 diopters ([D]; odds ratio, 3.69; 95% CI, 0.89-15.2). Only four of 12 participants (33.3%) with manifest PACG had been previously diagnosed, and one of 12 (8.3%) had peripheral iridotomy performed previously. Manifest PACG had caused blindness in one or both eyes in five of these 12 participants (41.7%); best-corrected distance visual acuity less than 20/400 in one or both eyes in four patients, and acuity less than 20/200 in one eye in another patient. Most (83.3%) of those with manifest PACG could be classified as having chronic form of the disease. We may have underestimated manifest PACG because visual fields were per- formed only on those with clinical suspicion of optic disc damage. Secondary ACG was present in two participants. The prevalence of PACG in this urban population in southern India is close to that reported recently in a Mongolian population. A large proportion of the PACG in this population was undiagnosed and untreated. Because visual loss resulting from PACG is potentially preventable if peripheral iridotomy or iridectomy is performed in the early stage, strategies for early detection of PACG could reduce the high risk of blindness resulting from PACG seen in this urban population in India.

Needle localization using a moving stylet/catheter in ultrasound-guided regional anesthesia: a feasibility study

NASA Astrophysics Data System (ADS)

Beigi, Parmida; Rohling, Robert

2014-03-01

Despite the wide range and long history of ultrasound guided needle insertions, an unresolved issue in many cases is clear needle visibility. A well-known ad hoc technique to detect the needle is to move the stylet and look for changes in the needle appearance. We present a new method to automatically locate a moving stylet/catheter within a stationary cannula using motion detection. We then use this information to detect the needle trajectory and the tip. The differences between the current frame and the previous frame are detected and localized, to minimize the influence of tissue global motions. A polynomial fit based on the detected needle axis determines the estimated stylet shaft trajectory, and the extent of the differences along the needle axis represents the tip. Over a few periodic movements of the stylet including its full insertion into the cannula to the tip, a combination of polynomial fits determines the needle trajectory and the last detected point represents the needle tip. Experiments are conducted in water bath and bovine muscle tissue for several stylet/catheter materials. Results show that a plastic stylet has the best needle shaft and tip localization accuracy in the water bath with RMSE = 0:16 mm and RMSE = 0:51 mm, respectively. In the bovine tissue, the needle tip was best localized with the plastic catheter with RMSE = 0:33 mm. The stylet tip localization was most accurate with the steel stylet, with RMSE = 2:81 mm and the shaft was best localized with the plastic catheter, with RMSE = 0:32 mm.

Training in Temporal Information Processing Ameliorates Phonetic Identification.

PubMed

Szymaszek, Aneta; Dacewicz, Anna; Urban, Paulina; Szelag, Elzbieta

2018-01-01

Many studies revealed a link between temporal information processing (TIP) in a millisecond range and speech perception. Previous studies indicated a dysfunction in TIP accompanied by deficient phonemic hearing in children with specific language impairment (SLI). In this study we concentrate in SLI on phonetic identification, using the voice-onset-time (VOT) phenomenon in which TIP is built-in. VOT is crucial for speech perception, as stop consonants (like /t/ vs. /d/) may be distinguished by an acoustic difference in time between the onsets of the consonant (stop release burst) and the following vibration of vocal folds (voicing). In healthy subjects two categories (voiced and unvoiced) are determined using VOT task. The present study aimed at verifying whether children with SLI indicate a similar pattern of phonetic identification as their healthy peers and whether the intervention based on TIP results in improved performance on the VOT task. Children aged from 5 to 8 years ( n = 47) were assigned into two groups: normal children without any language disability (NC, n = 20), and children with SLI ( n = 27). In the latter group participants were randomly classified into two treatment subgroups, i.e., experimental temporal training (EG, n = 14) and control non-temporal training (CG, n = 13). The analyzed indicators of phonetic identification were: (1) the boundary location (α) determined as the VOT value corresponding to 50% voicing/unvoicing distinctions; (2) ranges of voiced/unvoiced categories; (3) the slope of identification curve (β) reflecting the identification correctness; (4) percent of voiced distinctions within the applied VOT spectrum. The results indicated similar α values and similar ranges of voiced/unvoiced categories between SLI and NC. However, β in SLI was significantly higher than that in NC. After the intervention, the significant improvement of β was observed only in EG. They achieved the level of performance comparable to that observed in NC. The training-related improvement in CG was non-significant. Furthermore, only in EG the β values in post-test correlated with measures of TIP as well as with phonemic hearing obtained in our previous studies. These findings provide another evidence that TIP is omnipresent in language communication and reflected not only in phonemic hearing but also in phonetic identification.

Safety and feasibility of intra-operative device closure of atrial septal defect with transthoracic minimal invasion.

PubMed

Chen, Qiang; Cao, Hua; Zhang, Gui-Can; Chen, Liang-Wan; Chen, Dao-Zhong

2012-01-01

The study aims to evaluate the safety and feasibility of intra-operative device closure of atrial septal defect with transthoracic minimal invasion. From May 2006 to June 2009, 252 patients with secundum-type atrial septal defect closure were enrolled in our institution. The patients were divided into two groups, with 182 patients in group I with intra-operative device closure and 72 in group II with surgical closure. In group I, the patients' age ranged from 3 months to 62 years (mean±standard deviation, 19.0±16.7 years). This approach involved a transthoracic minimal invasion that was performed after full evaluation of the atrial septal defect by transthoracic echocardiography, deploying the device through the delivery sheath to occlude the atrial septal defect. In group I, 180 patients were occluded successfully under this approach. The size of the occluder device implanted ranged from 6 to 48 mm. Minor complications occurred, which included transient arrhythmias (n=23) and pleural effusion (n=15). Two patients with postoperative cardiac arrest were successfully cardiopulmonary resuscitated. Another two patients with occluder dislodged back into the right atrium were turned to surgical repair with cardiopulmonary bypass on the postoperative day. In group II, all patients were occluded successfully, and almost all patients needed blood transfusion and suffered from various minor complications. All discharged patients were followed up for 1-5 years. During this period, we found no recurrence, no thrombosis, even no device failure. In our comparative studies, group II had significantly longer intensive care unit (ICU) stay and hospital stay than group I (p<0.05). The cost for group I was less than group II (p<0.05). Intra-operative device closure of atrial septal defect with transthoracic minimal invasion is a safe and feasible technique. It had the advantages of cost savings, yielding better cosmetic results, and leaving less trauma than surgical closure.

Impact of National Clinical Guideline Recommendations for Revascularization of Persistently Occluded Infarct-Related Arteries on Clinical Practice in the United States

PubMed Central

Deyell, Marc W.; Buller, Christopher E.; Miller, Louis H.; Wang, Tracy Y.; Dai, David; Lamas, Gervasio A.; Srinivas, Vankeepuram S.; Hochman, Judith S.

2013-01-01

Background The Occluded Artery Trial (OAT) was a large, randomized controlled trial published in 2006 that demonstrated no benefit to routine percutaneous coronary intervention (PCI) of persistently totally occluded infarct-related arteries (IRA) identified a minimum of 24 hours (on calendar days 3–28) after myocardial infarction (MI). The purpose of this study was to determine the impact of OAT results and consequent change in guideline recommendations for PCI for treatment of persistently occluded IRAs. Methods We identified all patients enrolled in the CathPCI Registry, from 2005 to 2008, undergoing catheterization more than 24 hours after MI with a totally occluded native coronary artery and no major OAT exclusion criteria. We examined trends in monthly rates of PCI for occlusions after OAT publication and after guideline revisions. Because reporting of diagnostic catheterizations was not mandatory, we examined trends among hospitals in the highest quartile for reporting of diagnostic procedures. Results A total of 28 780 patient visits from 896 hospitals were included. Overall, we found no significant decline in the adjusted monthly rate of PCI of occlusions after publication of OAT (odds ratio [OR], 0.997; 95% confidence interval [CI], 0.989–1.006) or after guideline revisions (OR, 1.007; 95% CI, 0.992–1.022). Among hospitals consistently reporting diagnostic catheterizations, there was no significant decline after OAT publication (OR, 1.018; 95% CI, 0.995–1.042), and there was a trend toward decline after guideline revisions (OR, 0.963; 95% CI, 0.920–1.000). Conclusion These findings suggest that the results of OAT and consequent guideline revisions have not, to date, been fully incorporated into clinical practice in a large cross-section of hospitals in the United States. PMID:21747002

Nd:YAG photovaporization of residual equine guttural-pouch mycotic lesions after internal carotid occlusion

NASA Astrophysics Data System (ADS)

Tate, Lloyd P.; Tudor, R. A.; Little, Edwina D. E.

1998-07-01

Hospital records reviewed over a 12-year period determined that 6 horses had been presented for guttural pouch mycosis. All had a history of epistaxis and several had accompanying neurologic signs, including dysphagia. Initially, conformation of the disease was obtained by radiographic and endoscopic examinations. Surgical treatment was directed at controlling and preventing additional hemorrhage by occluding the arterial source of the hemorrhage. Direct treatment of the mycotic plaque present within the guttural pouch was conducted using transendoscopic technique to direct irradiation from the Nd:YAG laser. The protocol described for the laser application was successful in resolving the lesions and was less complicated and stressful than previously reported topically applied chemical protocols.

Bleeding Duodenal Varices Successfully Treated with Balloon-Occluded Retrograde Transvenous Obliteration (B-RTO) Assisted by CT During Arterial Portography

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

Tsurusaki, Masakatsu, E-mail: he3m-trsk@asahi-net.or.jp; Sugimoto, Koji; Matsumoto, Shinichi

2006-12-15

A 60-year-old woman with massive hemorrhage from duodenal varices was transferred to our hospital for the purpose of transcatheter intervention. Although digital subtraction arterial portography could not depict the entire pathway of collateral circulation, the efferent route of the duodenal varices was clearly demonstrated on subsequent CT during arterial portography. Balloon-occluded retrograde transvenous obliteration (B-RTO) of the varices was performed via the efferent vein and achieved complete thrombosis of the varices.

Transcatheter Retrieval of Embolized Atrial Septal Defect Occluder Device by Waist Capture Technique.

PubMed

Her, Ae-Young; Lim, Kyung-Hun; Shin, Eun-Seok

2018-01-27

This case study describes the successful percutaneous transcatheter retrieval of an embolized Amplatzer occluder device using the "waist capture technique" in a patient with an atrial septal defect. This technique allowed for stability of the Amplatzer device, compression of the atrial discs for easier removal, prevention of further embolization, and minimal injury to vasculature during device retrieval. This novel and effective technique can be used safely for the retrieval of Amplatzer devices in the venous system.

High-energy electron emission from metallic nano-tips driven by intense single-cycle terahertz pulses

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

Li, Sha; Jones, R. R.

Electrons ejected from atoms and subsequently driven to high energies in strong laser fields enable techniques from attosecond pulse generation to imaging with rescattered electrons. Analogous processes govern strong-field electron emission from nanostructures, where long wavelength radiation and large local field enhancements hold the promise for producing electrons with substantially higher energies, allowing for higher resolution time-resolved imaging. Here we report on the use of single-cycle terahertz pulses to drive electron emission from unbiased nano-tips. Energies exceeding 5 keV are observed, substantially greater than previously attained at higher drive frequencies. Despite large differences in the magnitude of the respective localmore » fields, we find that the maximum electron energies are only weakly dependent on the tip radius, for 10 nm« less

Improving the lateral resolution of quartz tuning fork-based sensors in liquid by integrating commercial AFM tips into the fiber end.

PubMed

Gonzalez, Laura; Martínez-Martín, David; Otero, Jorge; de Pablo, Pedro José; Puig-Vidal, Manel; Gómez-Herrero, Julio

2015-01-14

The use of quartz tuning fork sensors as probes for scanning probe microscopy is growing in popularity. Working in shear mode, some methods achieve a lateral resolution comparable with that obtained with standard cantilevered probes, but only in experiments conducted in air or vacuum. Here, we report a method to produce and use commercial AFM tips in electrically driven quartz tuning fork sensors operating in shear mode in a liquid environment. The process is based on attaching a standard AFM tip to the end of a fiber probe which has previously been sharpened. Only the end of the probe is immersed in the buffer solution during imaging. The lateral resolution achieved is about 6 times higher than that of the etched microfiber on its own.

Anomalous domain inversion in LiNbO3 single crystals investigated by scanning probe microscopy

NASA Astrophysics Data System (ADS)

Lilienblum, M.; Soergel, E.

2011-09-01

Ferroelectric domains were written in lithium niobate (LiNbO3) single crystals by applying voltage pulses to the tip of a scanning force microscope. The generated domains are subsequently imaged by piezoresponse force microscopy. As it has been previously observed not only full domains but also doughnut-shaped ones arise from tip-based domain formation. In this contribution, we present our experiments which were carried out with 10-20 μm thin LiNbO3 single crystals. We show that by choosing appropriate writing parameters, domains of predetermined shape (full or doughnut) can be reliably generated. In addition to the duration and the amplitude of the voltage pulse the moment of the retraction of the tip from the sample surface was found to be a crucial parameter for reproducible domain formation.

High-energy electron emission from metallic nano-tips driven by intense single-cycle terahertz pulses

DOE PAGES

Li, Sha; Jones, R. R.

2016-11-10

Electrons ejected from atoms and subsequently driven to high energies in strong laser fields enable techniques from attosecond pulse generation to imaging with rescattered electrons. Analogous processes govern strong-field electron emission from nanostructures, where long wavelength radiation and large local field enhancements hold the promise for producing electrons with substantially higher energies, allowing for higher resolution time-resolved imaging. Here we report on the use of single-cycle terahertz pulses to drive electron emission from unbiased nano-tips. Energies exceeding 5 keV are observed, substantially greater than previously attained at higher drive frequencies. Despite large differences in the magnitude of the respective localmore » fields, we find that the maximum electron energies are only weakly dependent on the tip radius, for 10 nm« less

In Candida albicans hyphae, Sec2p is physically associated with SEC2 mRNA on secretory vesicles.

PubMed

Caballero-Lima, David; Hautbergue, Guillaume M; Wilson, Stuart A; Sudbery, Peter E

2014-11-01

Candida albicans hyphae grow in a highly polarized fashion from their tips. This polarized growth requires the continuous delivery of secretory vesicles to the tip region. Vesicle delivery depends on Sec2p, the Guanine Exchange Factor (GEF) for the Rab GTPase Sec4p. GTP bound Sec4p is required for the transit of secretory vesicles from the trans-Golgi to sites of polarized growth. We previously showed that phosphorylation of Sec2p at residue S584 was necessary for Sec2p to support hyphal, but not yeast growth. Here we show that on secretory vesicles SEC2 mRNA is physically associated with Sec2p. Moreover, we show that the phosphorylation of S584 allows SEC2 mRNA to dissociate from Sec2p and we speculate that this is necessary for Sec2p function and/or translation. During hyphal extension, the growing tip may be separated from the nucleus by up to 15 μm. Transport of SEC2 mRNA on secretory vesicles to the tip localizes SEC2 translation to tip allowing a sufficient accumulation of this key protein at the site of polarized growth. © 2014 The Authors. Molecular Microbiology published by John Wiley & Sons Ltd.

Imaging diagnostics of pulsed plasma discharges in saline generated with various sharp pin powered electrodes

NASA Astrophysics Data System (ADS)

Asimakoulas, L.; Karim, M. L.; Dostal, L.; Krcma, F.; Graham, W. G.; Field, T. A.

2016-09-01

Plasmas formed by 1 ms pulses of between 180 and 300 V applied to sharp pin-like electrodes immersed in saline solution have been imaged with a Photron SA-X2 fast framing camera and an Andor iStar 510 ICCD camera. Stainless steel, Tungsten and Gold electrodes were investigated with tip diameters of 30 μm, 1 μm and < 1 μ m respectively. As previously observed, a vapour layer forms around the electrode prior to plasma ignition. For gold and stainless steel lower voltages were required to minimize electrode damage. Preliminary anlaysis indicates at lower voltages for all tips the fast framing results show that light emission is normally centred on a single small volume, which appears to move about, but remains close to the tip. In the case of Tungsten with higher voltages or longer pulses the tip of the needle can heat up to incandescent temperatures. At higher voltages shock wave fronts appear to be observed as the vapour layer collapses at the end of the voltage pulse. Backlighting and no lighting to observe bubble/vapour layer formation and emission due to plasma formation were employed. Sometimes at higher voltages a thicker vapour layer engulfs the tip and no plasma emission/current is observed.

The Widom line and dynamical crossover in supercritical water: Popular water models versus experiments

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

Corradini, D.; Rovere, M.; Gallo, P., E-mail: gallop@fis.uniroma3.it

2015-09-21

In a previous study [Gallo et al., Nat. Commun. 5, 5806 (2014)], we have shown an important connection between thermodynamic and dynamical properties of water in the supercritical region. In particular, by analyzing the experimental viscosity and the diffusion coefficient obtained in simulations performed using the TIP4P/2005 model, we have found that the line of response function maxima in the one phase region, the Widom line, is connected to a crossover from a liquid-like to a gas-like behavior of the transport coefficients. This is in agreement with recent experiments concerning the dynamics of supercritical simple fluids. We here show howmore » different popular water models (TIP4P/2005, TIP4P, SPC/E, TIP5P, and TIP3P) perform in reproducing thermodynamic and dynamic experimental properties in the supercritical region. In particular, the comparison with experiments shows that all the analyzed models are able to qualitatively predict the dynamical crossover from a liquid-like to a gas-like behavior upon crossing the Widom line. Some of the models perform better in reproducing the pressure-temperature slope of the Widom line of supercritical water once a rigid shift of the phase diagram is applied to bring the critical points to coincide with the experimental ones.« less

Tapping mode imaging and measurements with an inverted atomic force microscope.

PubMed

Chan, Sandra S F; Green, John-Bruce D

2006-07-18

This report demonstrates the successful use of the inverted atomic force microscope (i-AFM) for tapping mode AFM imaging of cantilever-supported samples. i-AFM is a mode of AFM operation in which a sample supported on a tipless cantilever is imaged by one of many tips in a microfabricated tip array. Tapping mode is an intermittent contact mode whereby the cantilever is oscillated at or near its resonance frequency, and the amplitude and/or phase are used to image the sample. In the process of demonstrating that tapping mode images could be obtained in the i-AFM design, it was observed that the amplitude of the cantilever oscillation decreased markedly as the cantilever and tip array were approached. The source of this damping of the cantilever oscillations was identified to be the well-known "squeeze film damping", and the extent of damping was a direct consequence of the relatively shorter tip heights for the tip arrays, as compared to those of commercially available tapping mode cantilevers with integrated tips. The functional form for the distance dependence of the damping coefficient is in excellent agreement with previously published models for squeeze film damping, and the values for the fitting parameters make physical sense. Although the severe damping reduces the cantilever free amplitude substantially, we found that we were still able to access the low-amplitude regime of oscillation necessary for attractive tapping mode imaging of fragile molecules.

Cultural Evolutionary Tipping Points in the Storage and Transmission of Information

PubMed Central

Bentley, R. Alexander; O’Brien, Michael J.

2012-01-01

Human culture has evolved through a series of major tipping points in information storage and communication. The first was the appearance of language, which enabled communication between brains and allowed humans to specialize in what they do and to participate in complex mating games. The second was information storage outside the brain, most obviously expressed in the “Upper Paleolithic Revolution” – the sudden proliferation of cave art, personal adornment, and ritual in Europe some 35,000–45,000 years ago. More recently, this storage has taken the form of writing, mass media, and now the Internet, which is arguably overwhelming humans’ ability to discern relevant information. The third tipping point was the appearance of technology capable of accumulating and manipulating vast amounts of information outside humans, thus removing them as bottlenecks to a seemingly self-perpetuating process of knowledge explosion. Important components of any discussion of cultural evolutionary tipping points are tempo and mode, given that the rate of change, as well as the kind of change, in information storage and transmission has not been constant over the previous million years. PMID:23267338

Cultural evolutionary tipping points in the storage and transmission of information.

PubMed

Bentley, R Alexander; O'Brien, Michael J

2012-01-01

Human culture has evolved through a series of major tipping points in information storage and communication. The first was the appearance of language, which enabled communication between brains and allowed humans to specialize in what they do and to participate in complex mating games. The second was information storage outside the brain, most obviously expressed in the "Upper Paleolithic Revolution" - the sudden proliferation of cave art, personal adornment, and ritual in Europe some 35,000-45,000 years ago. More recently, this storage has taken the form of writing, mass media, and now the Internet, which is arguably overwhelming humans' ability to discern relevant information. The third tipping point was the appearance of technology capable of accumulating and manipulating vast amounts of information outside humans, thus removing them as bottlenecks to a seemingly self-perpetuating process of knowledge explosion. Important components of any discussion of cultural evolutionary tipping points are tempo and mode, given that the rate of change, as well as the kind of change, in information storage and transmission has not been constant over the previous million years.

Selected mode of dendritic growth with n-fold symmetry in the presence of a forced flow

NASA Astrophysics Data System (ADS)

Alexandrov, D. V.; Galenko, P. K.

2017-07-01

The effect of n-fold crystal symmetry is investigated for a two-dimensional stable dendritic growth in the presence of a forced convective flow. We consider dendritic growth in a one-component undercooled liquid. The theory is developed for the parabolic solid-liquid surface of dendrite growing at arbitrary growth Péclet numbers keeping in mind small anisotropies of surface energy and growth kinetics. The selection criterion determining the stable growth velocity of the dendritic tip and its stable tip diameter is found on the basis of solvability analysis. The obtained criterion includes previously developed theories of thermally and kinetically controlled dendritic growth with convection for the case of four-fold crystal symmetry. The obtained nonlinear system of equations (representing the selection criterion and undercooling balance) for the determination of dendrite tip velocity and dendrite tip diameter is analytically solved in a parametric form. These exact solutions clearly demonstrate a transition between thermally and kinetically controlled growth regimes. In addition, we show that the dendrites with larger crystal symmetry grow faster than those with smaller symmetry.

Academic Language in Preschool: Research and Context

ERIC Educational Resources Information Center

Michael Luna, Sara

2017-01-01

Developing and scaffolding academic language is an important job of preschool teachers. This Teaching Tip provides five strategies that extend the topic of academic language by integrating previous research and field-based data into classroom practice.

Transcatheter closure of a small atrial septal defect with an Amplatzer™ patent foramen ovale occluder in a working dog with cyanosis and exercise intolerance at high altitude.

PubMed

Shelden, A; Wesselowski, S; Gordon, S G; Saunders, A B

2017-12-01

A 6.5-year-old male Border Collie presented for transcatheter closure of an atrial septal defect due to exercise intolerance and cyanosis while working and training at altitude. A small, left-to-right shunting secundum atrial septal defect was confirmed with no evidence of significant right-sided volume overload. Pulmonary hypertension with subsequent right-to-left interatrial shunting occurring during exercise at high altitude was suspected and prompted the closure of the defect due to the dog's continued athletic requirements. The anatomy of the defect prompted use of a patent foramen ovale occluder rather than an atrial septal defect occluder, which was deployed using a combination of fluoroscopic and transesophageal echocardiographic guidance. The owner did not report continued exercise intolerance or cyanosis and the dog's lifestyle and residence at altitude was unchanged. Copyright © 2017 Elsevier B.V. All rights reserved.

Transport of cardiovascular microbubbles in gas embolotherapy

NASA Astrophysics Data System (ADS)

Bull, Joseph L.; Calderon, Andres J.; Eshpuniyani, Brijesh; Valassis, Doug; Fowlkes, J. Brian

2006-11-01

This work is motivated by our ongoing development of a novel gas embolotherapy technique to occlude blood flow to tumors using gas bubbles that are selectively formed by the in vivo acoustic vaporization of liquid perfluorocarbon droplets. The droplets are small enough to pass through the microcirculation, but the subsequent bubbles are large enough to lodge in vessels. The uniformity of tumor infarction depends on the transport the blood-borne bubbles before they stick. We theoretically and experimentally investigate the transport of gas bubbles through bifurcating blood vessels. More homogenous bubble splitting is observed for higher values of capillary numbers and lower values of Bond numbers. The dependence of bubble lodging on flow parameters is also investigated, and several modes of bubble lodging and sticking are identified. These findings indicate the ability of gas bubbles to occlude flow and suggest the potential for development of treatment strategies that uniformly occlude the tumor circulation while minimizing collateral infarction. This work is supported by NSF grant BES-0301278 and NIH grant EB003541.

ST-depression in right precordial leads with inferior STEMI and occluded right coronary artery: intertwined anatomy and ischemic areas.

PubMed

De Gennaro, Luisa; Brunetti, Natale Daniele; Ruggiero, Massimo; Rutigliano, David; Locuratolo, Nicola; Di Biase, Matteo; Caldarola, Pasquale

2017-10-01

Right coronary artery (RCA) occlusion in inferior acute myocardial infarction is usually heralded by ST-elevation both in inferior and in right precordial leads. We report the case of a 68-year-old male, who presented marked ST-elevation in inferior leads, mirrored by ST-depression in anterior-septal and lateral leads. Right precordial lead electrocardiogram unexpectedly showed ST-depression V1R-V5R leads. Coronary angiography showed mid-left anterior descending (LAD) coronary near-complete occlusion with distal wrapping LAD. Left circumflex artery was not occluded, while RCA was occluded mid tract. The patient was treated with coronary angioplasty on RCA and LAD. Absence of ST-elevation in right precordial leads may be presumably explained by the presence of a large ischemic area distal to mid-LAD near-occlusive stenosis and of a long-wrapping LAD. Complex coronary anatomy and intertwined ischemic areas may underlie apparently discording electrocardiograms.

Spectral analysis of airflow sounds in patent versus occluded tracheostomy tubes: a pilot study in tracheostomized adult patients.

PubMed

Rao, A J; Niwa, H; Watanabe, Y; Fukuta, S; Yanagita, N

1990-05-01

Cannula occlusion is a life-threatening postoperative complication of tracheostomy. Current management largely relies on nursing care for prevention of fatalities because no proven mechanical, machine-based support monitoring exists. The objective of this paper was to address the problem of monitoring the state of cannula patency, based on analysis of airflow acoustic spectral patterns in tracheostomized adult patients in the patent and partially occluded cannula. Tracheal airflow sounds were picked up via a condenser microphone air-coupled to the skin just below the tracheal stoma. Signal output from Mic was amplified, high-pass filtered, digital tape-recorded, and analyzed on a mainframe computer. Although airflow frequencies for patient cannulae were predominantly low-pitched (0.1 to 0.3 kHz), occluded tubes had discrete high-pitched spectral peaks (1.3 to 1.6 kHz). These results suggest that frequency analysis of airflow sounds can identify a change in the status of cannula patency.

Factors Affecting Infants’ Manual Search for Occluded Objects and the Genesis of Object Permanence

PubMed Central

Moore, M. Keith; Meltzoff, Andrew N.

2009-01-01

Two experiments systematically examined factors that influence infants’ manual search for hidden objects (N = 96). Experiment 1 used a new procedure to assess infants’ search for partially versus totally occluded objects. Results showed that 8.75-month-old infants solved partial occlusions by removing the occluder and uncovering the object, but these same infants failed to use this skill on total occlusions. Experiment 2 used sound-producing objects to provide a perceptual clue to the objects’ hidden location. Sound clues significantly increased the success rate on total occlusions for 10-month-olds, but not for 8.75-month-olds. An identity development account is offered for why infants succeed on partial occlusions earlier than total occlusions and why sound helps only the older infants. We propose a mechanism for how infants use object identity as a basis for developing a notion of permanence. Implications are drawn for understanding the dissociation between looking-time and search assessments of object permanence. PMID:18036668

Feasibility and safety of a new generation of gore septal occluder device in children.

PubMed

Lombardi, Maristella; Tagliente, Maria R; Pirolo, Teodoro; Massari, Elena; Milella, Leonardo; Vairo, Ugo

2016-12-01

Transcatheter closure of an ostium secundum atrial septal defect (ASD) is now considered the standard care for most of children with the appropriate anatomy, and is a relatively well-tolerated procedure to reduce the clinical sequelae of ASD, with a low complication rate. The present case reports describe our clinical experience of the percutaneous closure of a secundum ASD in 10 children between December 2011 and November 2012, by means of a new generation of device, the GORE Septal Occluder device. The implantation was successful in all except two cases, the device being properly placed and deployed without malposition or embolization in the catheterization laboratory. No complications were related to the procedure. The successful implant was confirmed and no major adverse events were documented in the following 3-12 months. The new GORE Septal Occluder device appears to be a feasible, well-tolerated and successful tool for the closure of an ASD of 15 mm or less in childhood.

Factors affecting infants' manual search for occluded objects and the genesis of object permanence.

PubMed

Moore, M Keith; Meltzoff, Andrew N

2008-04-01

Two experiments systematically examined factors that influence infants' manual search for hidden objects (N=96). Experiment 1 used a new procedure to assess infants' search for partially versus totally occluded objects. Results showed that 8.75-month-old infants solved partial occlusions by removing the occluder and uncovering the object, but these same infants failed to use this skill on total occlusions. Experiment 2 used sound-producing objects to provide a perceptual clue to the objects' hidden location. Sound clues significantly increased the success rate on total occlusions for 10-month-olds, but not for 8.75-month-olds. An identity development account is offered for why infants succeed on partial occlusions earlier than total occlusions and why sound helps only the older infants. We propose a mechanism for how infants use object identity as a basis for developing a notion of permanence. Implications are drawn for understanding the dissociation between looking time and search assessments of object permanence.

Incorporating Phase-Dependent Polarizability in Non-Additive Electrostatic Models for Molecular Dynamics Simulations of the Aqueous Liquid-Vapor Interface.

PubMed

Bauer, Brad A; Warren, G Lee; Patel, Sandeep

2009-02-10

We discuss a new classical water force field that explicitly accounts for differences in polarizability between liquid and vapor phases. The TIP4P-QDP (4-point transferable intermolecular potential with charge dependent-polarizability) force field is a modification of the original TIP4P-FQ fluctuating charge water force field of Rick et al.(1) that self-consistently adjusts its atomic hardness parameters via a scaling function dependent on the M-site charge. The electronegativity (χ) parameters are also scaled in order to reproduce condensed-phase dipole moments of comparable magnitude to TIP4P-FQ. TIP4P-QDP is parameterized to reproduce experimental gas-phase and select condensed-phase properties. The TIP4P-QDP water model possesses a gas phase polarizability of 1.40 Å(3) and gas-phase dipole moment of 1.85 Debye, in excellent agreement with experiment and high-level ab initio predictions. The liquid density of TIP4P-QDP is 0.9954(±0.0002) g/cm(3) at 298 K and 1 atmosphere, and the enthalpy of vaporization is 10.55(±0.12) kcal/mol. Other condensed-phase properties such as the isobaric heat capacity, isothermal compressibility, and diffusion constant are also calculated within reasonable accuracy of experiment and consistent with predictions of other current state-of-the-art water force fields. The average molecular dipole moment of TIP4P-QDP in the condensed phase is 2.641(±0.001) Debye, approximately 0.02 Debye higher than TIP4P-FQ and within the range of values currently surmised for the bulk liquid. The dielectric constant, ε = 85.8 ± 1.0, is 10% higher than experiment. This is reasoned to be due to the increase in the condensed phase dipole moment over TIP4P-FQ, which estimates ε remarkably well. Radial distribution functions for TIP4P-QDP and TIP4P-FQ show similar features, with TIP4P-QDP showing slightly reduced peak heights and subtle shifts towards larger distance interactions. Since the greatest effects of the phase-dependent polarizability are anticipated in regions with both liquid and vapor character, interfacial simulations of TIP4P-QDP were performed and compared to TIP4P-FQ, a static polarizability analog. Despite similar features in density profiles such as the position of the GDS and interfacial width, enhanced dipole moments are observed for the TIP4P-QDP interface and onset of the vapor phase. Water orientational profiles show an increased preference (over TIP4P-FQ) in the orientation of the permanent dipole vector of the molecule within the interface; an enhanced z-induced dipole moment directly results from this preference. Hydrogen bond formation is lower, on average, in the bulk for TIP4P-QDP than TIP4P-FQ. However, the average number of hydrogen bonds formed by TIP4P-QDP in the interface exceeds that of TIP4P-FQ, and observed hydrogen bond networks extend further into the gaseous region. The TIP4P-QDP interfacial potential, calculated to be -11.98(±0.08) kcal/mol, is less favorable than that for TIP4P-FQ by approximately 2% as a result of a diminished quadrupole contribution. Surface tension is calculated within a 1.3% reduction from the experimental value. Results reported demonstrate TIP4P-QDP as a model comparable to the popular TIP4P-FQ while accounting for a physical effect previously neglected by other water models. Further refinements to this model, as well as future applications are discussed.

Incorporating Phase-Dependent Polarizability in Non-Additive Electrostatic Models for Molecular Dynamics Simulations of the Aqueous Liquid-Vapor Interface

PubMed Central

Bauer, Brad A.; Warren, G. Lee; Patel, Sandeep

2012-01-01

We discuss a new classical water force field that explicitly accounts for differences in polarizability between liquid and vapor phases. The TIP4P-QDP (4-point transferable intermolecular potential with charge dependent-polarizability) force field is a modification of the original TIP4P-FQ fluctuating charge water force field of Rick et al.1 that self-consistently adjusts its atomic hardness parameters via a scaling function dependent on the M-site charge. The electronegativity (χ) parameters are also scaled in order to reproduce condensed-phase dipole moments of comparable magnitude to TIP4P-FQ. TIP4P-QDP is parameterized to reproduce experimental gas-phase and select condensed-phase properties. The TIP4P-QDP water model possesses a gas phase polarizability of 1.40 Å3 and gas-phase dipole moment of 1.85 Debye, in excellent agreement with experiment and high-level ab initio predictions. The liquid density of TIP4P-QDP is 0.9954(±0.0002) g/cm3 at 298 K and 1 atmosphere, and the enthalpy of vaporization is 10.55(±0.12) kcal/mol. Other condensed-phase properties such as the isobaric heat capacity, isothermal compressibility, and diffusion constant are also calculated within reasonable accuracy of experiment and consistent with predictions of other current state-of-the-art water force fields. The average molecular dipole moment of TIP4P-QDP in the condensed phase is 2.641(±0.001) Debye, approximately 0.02 Debye higher than TIP4P-FQ and within the range of values currently surmised for the bulk liquid. The dielectric constant, ε = 85.8 ± 1.0, is 10% higher than experiment. This is reasoned to be due to the increase in the condensed phase dipole moment over TIP4P-FQ, which estimates ε remarkably well. Radial distribution functions for TIP4P-QDP and TIP4P-FQ show similar features, with TIP4P-QDP showing slightly reduced peak heights and subtle shifts towards larger distance interactions. Since the greatest effects of the phase-dependent polarizability are anticipated in regions with both liquid and vapor character, interfacial simulations of TIP4P-QDP were performed and compared to TIP4P-FQ, a static polarizability analog. Despite similar features in density profiles such as the position of the GDS and interfacial width, enhanced dipole moments are observed for the TIP4P-QDP interface and onset of the vapor phase. Water orientational profiles show an increased preference (over TIP4P-FQ) in the orientation of the permanent dipole vector of the molecule within the interface; an enhanced z-induced dipole moment directly results from this preference. Hydrogen bond formation is lower, on average, in the bulk for TIP4P-QDP than TIP4P-FQ. However, the average number of hydrogen bonds formed by TIP4P-QDP in the interface exceeds that of TIP4P-FQ, and observed hydrogen bond networks extend further into the gaseous region. The TIP4P-QDP interfacial potential, calculated to be -11.98(±0.08) kcal/mol, is less favorable than that for TIP4P-FQ by approximately 2% as a result of a diminished quadrupole contribution. Surface tension is calculated within a 1.3% reduction from the experimental value. Results reported demonstrate TIP4P-QDP as a model comparable to the popular TIP4P-FQ while accounting for a physical effect previously neglected by other water models. Further refinements to this model, as well as future applications are discussed. PMID:23133341

A mathematical simulation of the tip-apex distance and the calcar-referenced tip-apex distance for intertrochanteric fractures reduced with lag screws.

PubMed

Li, Shuang; Chang, Shi-Min; Jin, Yan-Min; Zhang, Ying-Qi; Niu, Wen-Xin; Du, Shou-Chao; Zhang, Li-Zhi; Ma, Hui

2016-06-01

As a predictor of the risk of lag screw cutout, it was recommended that keeping tip-apex distance (TAD)<25mm and placing the screw centrally or inferiorly, but positioning the lag screw too inferiorly in the head would produce TAD>25mm. We aim to simulate various positions of the lag screw in the femoral head and identify whether 25mm is a suitable cut-off value that favours all sizes of femoral heads with intertrochanteric fractures of the hip. Using a general mathematical software, the positions of the screw tip points were simulated. The virtual anterior-posterior and lateral views were then visualised, and the locus of the screw tips was projected into a Cartesian coordinate system according to the TAD and calcar-referenced tip-apex distance (CalTAD) formulas. Each original virtual anterior-posterior and lateral image was zoomed and compiled to match a calculated average image. The screw tip points were recorded, traced and compiled into volumes which could be used to visualise the screw's movements and positioning within the femoral head. The extracted volumes were calculated when 10mm

Evolution of a double amino acid substitution in the 5-enolpyruvylshikimate-3-phosphate synthase in Eleusine indica conferring high-level glyphosate resistance.

PubMed

Yu, Qin; Jalaludin, Adam; Han, Heping; Chen, Ming; Sammons, R Douglas; Powles, Stephen B

2015-04-01

Glyphosate is the most important and widely used herbicide in world agriculture. Intensive glyphosate selection has resulted in the widespread evolution of glyphosate-resistant weed populations, threatening the sustainability of this valuable once-in-a-century agrochemical. Field-evolved glyphosate resistance due to known resistance mechanisms is generally low to modest. Here, working with a highly glyphosate-resistant Eleusine indica population, we identified a double amino acid substitution (T102I+P106S [TIPS]) in the 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) gene in glyphosate-resistant individuals. This TIPS mutation recreates the biotechnology-engineered commercial first generation glyphosate-tolerant EPSPS in corn (Zea mays) and now in other crops. In E. indica, the naturally evolved TIPS mutants are highly (more than 180-fold) resistant to glyphosate compared with the wild type and more resistant (more than 32-fold) than the previously known P106S mutants. The E. indica TIPS EPSPS showed very high-level (2,647-fold) in vitro resistance to glyphosate relative to the wild type and is more resistant (600-fold) than the P106S variant. The evolution of the TIPS mutation in crop fields under glyphosate selection is likely a sequential event, with the P106S mutation being selected first and fixed, followed by the T102I mutation to create the highly resistant TIPS EPSPS. The sequential evolution of the TIPS mutation endowing high-level glyphosate resistance is an important mechanism by which plants adapt to intense herbicide selection and a dramatic example of evolution in action. © 2015 American Society of Plant Biologists. All Rights Reserved.

Evolution of a Double Amino Acid Substitution in the 5-Enolpyruvylshikimate-3-Phosphate Synthase in Eleusine indica Conferring High-Level Glyphosate Resistance1

PubMed Central

Yu, Qin; Jalaludin, Adam; Han, Heping; Chen, Ming; Sammons, R. Douglas; Powles, Stephen B.

2015-01-01

Glyphosate is the most important and widely used herbicide in world agriculture. Intensive glyphosate selection has resulted in the widespread evolution of glyphosate-resistant weed populations, threatening the sustainability of this valuable once-in-a-century agrochemical. Field-evolved glyphosate resistance due to known resistance mechanisms is generally low to modest. Here, working with a highly glyphosate-resistant Eleusine indica population, we identified a double amino acid substitution (T102I + P106S [TIPS]) in the 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) gene in glyphosate-resistant individuals. This TIPS mutation recreates the biotechnology-engineered commercial first generation glyphosate-tolerant EPSPS in corn (Zea mays) and now in other crops. In E. indica, the naturally evolved TIPS mutants are highly (more than 180-fold) resistant to glyphosate compared with the wild type and more resistant (more than 32-fold) than the previously known P106S mutants. The E. indica TIPS EPSPS showed very high-level (2,647-fold) in vitro resistance to glyphosate relative to the wild type and is more resistant (600-fold) than the P106S variant. The evolution of the TIPS mutation in crop fields under glyphosate selection is likely a sequential event, with the P106S mutation being selected first and fixed, followed by the T102I mutation to create the highly resistant TIPS EPSPS. The sequential evolution of the TIPS mutation endowing high-level glyphosate resistance is an important mechanism by which plants adapt to intense herbicide selection and a dramatic example of evolution in action. PMID:25717039

Human Papillomavirus Type 18 E6 Protein Binds the Cellular PDZ Protein TIP-2/GIPC, Which Is Involved in Transforming Growth Factor β Signaling and Triggers Its Degradation by the Proteasome

PubMed Central

Favre-Bonvin, Arnaud; Reynaud, Caroline; Kretz-Remy, Carole; Jalinot, Pierre

2005-01-01

Several viral proteins expressed by DNA or RNA transforming viruses have the particular property of binding via their C-terminal end to various cellular proteins with PDZ domains. This study is focused on the PDZ protein TIP-2/GIPC, which was originally identified in two-hybrid screens performed with two different baits: the human T-cell leukemia virus type 1 Tax oncoprotein and the regulator of G signaling RGS-GAIP. Further studies have shown that TIP-2/GIPC is also able to associate with the cytoplasmic domains of various transmembrane proteins. In this report we show that TIP-2/GIPC interacts with the E6 protein of human papillomavirus type 18 (HPV-18). This event triggers polyubiquitination and proteasome-mediated degradation of the cellular protein. In agreement with this observation, silencing of E6 by RNA interference in HeLa cells causes an increase in the intracellular TIP-2/GIPC level. This PDZ protein has been previously found to be involved in transforming growth factor β (TGF-β) signaling by favoring expression of the TGF-β type III receptor at the cell membrane. In line with this activity of TIP-2/GIPC, we observed that depletion of this protein in HeLa cells hampers induction of the Id3 gene by TGF-β treatment and also diminishes the antiproliferative effect of this cytokine. Conversely, silencing of E6 increases the expression of Id3 and blocks proliferation of HeLa cells. These results support the notion that HPV-18 E6 renders cells less sensitive to the cytostatic effect of TGF-β by lowering the intracellular amount of TIP-2/GIPC. PMID:15767424

Retrieval of large Occlutech Figula Flex septal defect occluders using a commercially available bioptome: proof of concept.

PubMed

Georgiev, Stanimir; Tanase, Daniel; Genz, Thomas; Ewert, Peter; Naumann, Susanne; Pozza, Robert Dalla; Eicken, Andreas

2018-07-01

This study aimed to develop a method for retrieval of the new meshed nitinol atrial septal defect occluders - Ceraflex and Occlutech. The newly developed atrial septal defect occluders have potential benefits considering implantation, but concerns regarding their removal in case of embolisation have been raised. Over 21 years, 1449 patients underwent interventional atrial septal defect occlusion in our institution. We reviewed the cases of embolisation of the device, developed a strategy for device removal, and tested it on the benchside and in animal tests. In 11 patients (0.8%), the intended atrial septal defect occlusion was complicated by an embolisation of the device. In contrast to the Amplatzer septal occluders, retrieval of Occlutech devices larger than 16 mm with snare techniques was impossible. In benchside tests, this was confirmed and a new method for removal of large meshed devices was developed. This involved the commercially available Maslanka® biopsy forceps. The feasibility of this technique in vivo was tested in a pig model. During animal tests, using the Maslanka biopsy forceps it was possible to interventionally retrieve embolised Ceraflex and Occlutech devices of different sizes - 10, 16, 30, and 40 mm - into a 12-F sheath. It was impossible to retrieve Occlutech and Ceraflex devices larger than 16 mm into a large sheath in vivo and during benchside tests. However, this was feasible on the bench and in vivo using the Maslanka biopsy forceps even with the largest available devices.

Septate Junction Proteins Play Essential Roles in Morphogenesis Throughout Embryonic Development in Drosophila

PubMed Central

Hall, Sonia; Ward, Robert E.

2016-01-01

The septate junction (SJ) is the occluding junction found in the ectodermal epithelia of invertebrate organisms, and is essential to maintain chemically distinct compartments in epithelial organs, to provide the blood–brain barrier in the nervous system, and to provide an important line of defense against invading pathogens. More than 20 genes have been identified to function in the establishment or maintenance of SJs in Drosophila melanogaster. Numerous studies have demonstrated the cell biological function of these proteins in establishing the occluding junction, whereas very few studies have examined further developmental roles for them. Here we examined embryos with mutations in nine different core SJ genes and found that all nine result in defects in embryonic development as early as germ band retraction, with the most penetrant defect observed in head involution. SJ genes are also required for cell shape changes and cell rearrangements that drive the elongation of the salivary gland during midembryogenesis. Interestingly, these developmental events occur at a time prior to the formation of the occluding junction, when SJ proteins localize along the lateral membrane and have not yet coalesced into the region of the SJ. Together, these observations reveal an underappreciated role for a large group of SJ genes in essential developmental events during embryogenesis, and suggest that the function of these proteins in facilitating cell shape changes and rearrangements is independent of their role in the occluding junction. PMID:27261004

Effect of non-Newtonian characteristics of blood on magnetic particle capture in occluded blood vessel

NASA Astrophysics Data System (ADS)

Bose, Sayan; Banerjee, Moloy

2015-01-01

Magnetic nanoparticles drug carriers continue to attract considerable interest for drug targeting in the treatment of cancer and other pathological conditions. Magnetic carrier particles with surface-bound drug molecules are injected into the vascular system upstream from the desired target site, and are captured at the target site via a local applied magnetic field. Herein, a numerical investigation of steady magnetic drug targeting (MDT) using functionalized magnetic micro-spheres in partly occluded blood vessel having a 90° bent is presented considering the effects of non-Newtonian characteristics of blood. An Eulerian-Lagrangian technique is adopted to resolve the hemodynamic flow and the motion of the magnetic particles in the flow using ANSYS FLUENT. An implantable infinitely long cylindrical current carrying conductor is used to create the requisite magnetic field. Targeted transport of the magnetic particles in a partly occluded vessel differs distinctly from the same in a regular unblocked vessel. Parametric investigation is conducted and the influence of the insert configuration and its position from the central plane of the artery (zoffset), particle size (dp) and its magnetic property (χ) and the magnitude of current (I) on the "capture efficiency" (CE) is reported. Analysis shows that there exists an optimum regime of operating parameters for which deposition of the drug carrying magnetic particles in a target zone on the partly occluded vessel wall can be maximized. The results provide useful design bases for in vitro set up for the investigation of MDT in stenosed blood vessels.

A New Coated Nitinol Occluder for Transcatheter Closure of Ventricular Septal Defects in a Canine Model

PubMed Central

Zhou, Yong; Chen, Feng; Huang, Xinmiao; Zhao, Xianxian; Wu, Hong; Bai, Yuan; Qin, Yongwen

2013-01-01

Aims. This study evaluated feasibility and safety of implanting the polyester-coated nitinol ventricular septal defect occluder (pcVSDO) in the canine model. Methods and Results. VSD models were successfully established by transseptal ventricular septal puncture via the right jugular vein in 15 out of 18 canines. Two types of VSDOs were implanted, either with pcVSDOs (n = 8) as the new type occluder group or with the commercial ventricular septal defect occluders (VSDOs, n = 7, Shanghai Sharp Memory Alloy Co. Ltd.) as the control group. Sheath size was 10 French (10 Fr) in two groups. Then the general state of the canines was observed after implantation. ECG and TTE were performed, respectively, at 7, 30, 90 days of follow-up. The canines were sacrificed at these time points for pathological and scanning electron microscopy examination. The devices were successfully implanted in all 15 canines and were retrievable and repositionable. There was no thrombus formation on the device or occurrence of complete heart block. The pcVSDO surface implanted at day 7 was already covered with neotissue by gross examination, and it completed endothelialization at day 30, while the commercial VSDO was covered with the neotissue in 30th day and the complete endothelialization in 90th day. Conclusion. The study shows that pcVSDO is feasible and safe to close canine VSD model and has good biocompatibility and shorter time of endothelialization. PMID:24066289

Intraocular pressure spike after YAG iridotomy in patients with pigment dispersion.

PubMed

Birt, Catherine M

2004-04-01

The role of laser peripheral iridotomy to break a suspected reverse pupil block in the long-term control of pigment dispersion is promising, but the usefulness of this procedure has not been completely established. The author examined whether patients with pigment dispersion are at higher risk for an intraocular pressure (IOP) spike after laser peripheral iridotomy due to possible compromise of trabecular meshwork function, compared with patients undergoing prophylactic peripheral iridotomy for an occludable angle. Data were collected prospectively on the first eye of 87 patients with occludable angles and 13 patients with pigment dispersion treated with peripheral laser iridotomy between November 1995 and October 1996 at the glaucoma service of a university-affiliated hospital in Toronto. All patients received one drop of 0.5% apraclonidine before the procedure. IOP was measured before and 1 and 24 hours after the procedure. There was no difference between the two groups in the distribution of right vs. left eyes, sex, race, the mean total energy required to produce a patent iridotomy, the mean number of medications used or the mean IOP before the procedure. The patients with pigment dispersion were significantly younger than those with occludable angles (mean age [and standard deviation (SD)] 40.5 [9.45] years vs. 66.4 [10.78] years) (p < 0.001). There was no difference between the two groups in mean IOP at 1 hour or at 24 hours. Twenty-nine patients (33%) in the occludable angle group and seven (54%) in the pigment dispersion group had an IOP spike greater than 2 mm Hg after the procedure (p = 0.001). Among these patients, the mean IOP (36.4 [SD 10.83] mm Hg vs. 30.3 [SD 7.04] mm Hg, p = 0.05) and the mean rise in IOP (14.0 [SD 10.63] mm Hg vs. 8.7 [SD 4.73] mm Hg, p = 0.04) were significantly higher in those with pigment dispersion than in those with occludable angles. Among the patients who used antiglaucoma medications before the procedure or had a prelaser IOP level greater than 22 mm Hg, those with pigment dispersion were more likely than those with occludable angles to have an IOP spike at 1 hour (p < or = 0.005). Patients with pigment dispersion undergoing iridotomy to break a reverse pupil block should be carefully assessed after the procedure, as significant pressure spikes requiring treatment may occur.

Human skin absorption of Bis-2-(chloroethyl)sulphide (sulphur mustard) in vitro.

PubMed

Chilcott, R P; Jenner, J; Carrick, W; Hotchkiss, S A; Rice, P

2000-01-01

The purpose of this study was to measure the absorption and intra-epidermal fate of 35S-radiolabelled sulphur mustard (35SM) in human breast skin in vitro. Skin (full-thickness or heat-separated epidermis) was placed into static diffusion cells and was exposed to droplets of liquid 35SM or saturated 35SM vapour. Amounts of 35SM penetrating the skin were measured from which skin absorption rates were calculated. Unbound radiolabel was washed from the surface, extracted from the skin and analysed to determine the identity of the radiolabelled species in order to measure the extent of hydrolysis of sulphur mustard. Penetration rates of liquid 35SM measured in vitro (71-294 microg cm(-2) h(-1)) were in agreement with those measured previously in vivo using human volunteers (60-240 microg cm(-2) h(-1)). Rates of liquid 35SM skin absorption under occluded, infinite dose conditions were highest through heat-separated epidermal membranes (294+/-58 microg cm(-2) h(-1)) and lowest through full-thickness skin (71+/-14 microg cm(-2) h(-1)). Fluxes of saturated 35SM vapour (110+/-75 microg cm(-2) h(-1)) through heat-separated membranes were similar to those previously measured through human forearm skin in vivo (162 microg cm(-2) h(-1)). Although hydrolysis of 35SM did occur, both on the surface and within the skin, it accounted for only a small percentage of the total applied dose (<2.7+/-1.2%). The difference in total amount of liquid 35SM penetrated between occluded and unoccluded conditions in vitro (79+/-14%) was similar to that lost as vapour from unoccluded skin in vivo (80%). A substantial reservoir of 35SM (14-36% of the applied dose) was measured within heat-separated epidermal membranes for up to 24 h which may have significant implications for the management of personnel exposed to sulphur mustard.

A tip-localized RhoGAP controls cell polarity by globally inhibiting Rho GTPase at the cell apex.

PubMed

Hwang, Jae-Ung; Vernoud, Vanessa; Szumlanski, Amy; Nielsen, Erik; Yang, Zhenbiao

2008-12-23

Highly elongated eukaryotic cells (e.g., neuronal axons, fungal hyphae, and pollen tubes) are generated through continuous apically restricted growth (tip growth), which universally requires tip-localized Rho GTPases. We used the oscillating pollen tube as a model system to determine the function and regulation of Rho GTPases in tip growth. Our previous work showed that the spatiotemporal dynamics of the apical cap of the activated Rho-like GTPase from Plant 1 (ROP1) are critical for tip growth in pollen tubes. However, the underlying mechanism for the generation and maintenance of this dynamic apical cap is poorly understood. A screen for mutations that enhance ROP1-overexpression-induced depolarization of pollen-tube growth identified REN1 (ROP1 enhancer 1) in Arabidopsis, whose null mutations turn elongated pollen tubes into bulbous cells. REN1 encodes a novel Rho GTPase-activating protein (RhoGAP) required for restricting the ROP1 activity to the pollen-tube tip. REN1 was localized to exocytic vesicles accumulated in the pollen-tube apex, as well as to the apical plasma membrane at the site of ROP1 activation. The apical localization of REN1 and its function in controlling growth polarity was compromised by disruption of ROP1-dependent F-actin and vesicular trafficking, which indicates that REN1 targeting and function is regulated by ROP1 downstream signaling. Our findings suggest that the REN1 RhoGAP controls a negative-feedback-based global inhibition of ROP1. This function provides a critical self-organizing mechanism, by which ROP signaling is spatially limited to the growth site and temporally oscillates during continuous tip growth. Similar spatiotemporal control of Rho GTPase signaling may also play an important role in cell-polarity control in other systems, including tip growth in fungi and cell movement in animals.

SELF ALIGNED TIP DEINSULATION OF ATOMIC LAYER DEPOSITED AL2O3 AND PARYLENE C COATED UTAH ELECTRODE ARRAY BASED NEURAL INTERFACES

PubMed Central

Xie, Xianzong; Rieth, Loren; Negi, Sandeep; Bhandari, Rajmohan; Caldwell, Ryan; Sharma, Rohit; Tathireddy, Prashant; Solzbacher, Florian

2014-01-01

The recently developed alumina and Parylene C bi-layer encapsulation improved the lifetime of neural interfaces. Tip deinsulation of Utah electrode array based neural interfaces is challenging due to the complex 3D geometries and high aspect ratios of the devices. A three-step self-aligned process was developed for tip deinsulation of bilayer encapsulated arrays. The deinsulation process utilizes laser ablation to remove Parylene C, O2 reactive ion etching to remove carbon and Parylene residues, and buffered oxide etch to remove alumina deposited by atomic layer deposition, and expose the IrOx tip metallization. The deinsulated iridium oxide area was characterized by scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, and electrochemical impedance spectroscopy to determine the morphology, surface morphology, composition, and electrical properties of the deposited layers and deinsulated tips. The alumina layer was found to prevent the formation of micro cracks on iridium oxide during the laser ablation process, which has been previously reported as a challenge for laser deinsulation of Parylene films. The charge injection capacity, charge storage capacity, and impedance of deinsulated iridium oxide were characterized to determine the deinsulation efficacy compared to Parylene-only insulation. Deinsulated iridium oxide with bilayer encapsulation had higher charge injection capacity (240 vs 320 nC) and similar electrochemical impedance (2.5 vs 2.5 kΩ) compared to deinsulated iridium oxide with only Parylene coating for an area of 2 × 10−4 cm2. Tip impedances were in the ranges of 20 to 50 kΩ, with median of 32 KΩ and standard deviation of 30 kΩ, showing the effectiveness of the self-aligned deinsulation process for alumina and Parylene C bi-layer encapsulation. The relatively uniform tip impedance values demonstrated the consistency of tip exposures. PMID:24771981

Extended capture range for focus-diverse phase retrieval in segmented aperture systems using geometrical optics.

PubMed

Jurling, Alden S; Fienup, James R

2014-03-01

Extending previous work by Thurman on wavefront sensing for segmented-aperture systems, we developed an algorithm for estimating segment tips and tilts from multiple point spread functions in different defocused planes. We also developed methods for overcoming two common modes for stagnation in nonlinear optimization-based phase retrieval algorithms for segmented systems. We showed that when used together, these methods largely solve the capture range problem in focus-diverse phase retrieval for segmented systems with large tips and tilts. Monte Carlo simulations produced a rate of success better than 98% for the combined approach.

Filling gaps in visual motion for target capture

PubMed Central

Bosco, Gianfranco; Delle Monache, Sergio; Gravano, Silvio; Indovina, Iole; La Scaleia, Barbara; Maffei, Vincenzo; Zago, Myrka; Lacquaniti, Francesco

2015-01-01

A remarkable challenge our brain must face constantly when interacting with the environment is represented by ambiguous and, at times, even missing sensory information. This is particularly compelling for visual information, being the main sensory system we rely upon to gather cues about the external world. It is not uncommon, for example, that objects catching our attention may disappear temporarily from view, occluded by visual obstacles in the foreground. Nevertheless, we are often able to keep our gaze on them throughout the occlusion or even catch them on the fly in the face of the transient lack of visual motion information. This implies that the brain can fill the gaps of missing sensory information by extrapolating the object motion through the occlusion. In recent years, much experimental evidence has been accumulated that both perceptual and motor processes exploit visual motion extrapolation mechanisms. Moreover, neurophysiological and neuroimaging studies have identified brain regions potentially involved in the predictive representation of the occluded target motion. Within this framework, ocular pursuit and manual interceptive behavior have proven to be useful experimental models for investigating visual extrapolation mechanisms. Studies in these fields have pointed out that visual motion extrapolation processes depend on manifold information related to short-term memory representations of the target motion before the occlusion, as well as to longer term representations derived from previous experience with the environment. We will review recent oculomotor and manual interception literature to provide up-to-date views on the neurophysiological underpinnings of visual motion extrapolation. PMID:25755637

Filling gaps in visual motion for target capture.

PubMed

Bosco, Gianfranco; Monache, Sergio Delle; Gravano, Silvio; Indovina, Iole; La Scaleia, Barbara; Maffei, Vincenzo; Zago, Myrka; Lacquaniti, Francesco

2015-01-01

A remarkable challenge our brain must face constantly when interacting with the environment is represented by ambiguous and, at times, even missing sensory information. This is particularly compelling for visual information, being the main sensory system we rely upon to gather cues about the external world. It is not uncommon, for example, that objects catching our attention may disappear temporarily from view, occluded by visual obstacles in the foreground. Nevertheless, we are often able to keep our gaze on them throughout the occlusion or even catch them on the fly in the face of the transient lack of visual motion information. This implies that the brain can fill the gaps of missing sensory information by extrapolating the object motion through the occlusion. In recent years, much experimental evidence has been accumulated that both perceptual and motor processes exploit visual motion extrapolation mechanisms. Moreover, neurophysiological and neuroimaging studies have identified brain regions potentially involved in the predictive representation of the occluded target motion. Within this framework, ocular pursuit and manual interceptive behavior have proven to be useful experimental models for investigating visual extrapolation mechanisms. Studies in these fields have pointed out that visual motion extrapolation processes depend on manifold information related to short-term memory representations of the target motion before the occlusion, as well as to longer term representations derived from previous experience with the environment. We will review recent oculomotor and manual interception literature to provide up-to-date views on the neurophysiological underpinnings of visual motion extrapolation.

End-diastolic fractional flow reserve: comparison with conventional full-cardiac cycle fractional flow reserve.

PubMed

Chalyan, David A; Zhang, Zhang; Takarada, Shigeho; Molloi, Sabee

2014-02-01

Diastolic fractional flow reserve (dFFR) has been shown to be highly sensitive for detection of inducible myocardial ischemia. However, its reliance on measurement of left-ventricular pressure for zero-flow pressure correction, as well as manual extraction of the diastolic interval, has been its major limitation. Given previous reports of minimal zero-flow pressure at end-diastole, we compared instantaneous ECG-gated end-diastolic FFR with conventional full-cardiac cycle FFR and other diastolic indices in the porcine model. Measurements of FFR in the left anterior descending and left circumflex arteries were performed in an open-chest swine model with an external occluder device on the coronary artery used to produce varying degrees of epicardial stenosis. An ultrasound flow-probe that was placed proximal to the occluder measured absolute blood flow in ml/min, and it was used as a gold standard for FFR measurement. A total of 17 measurements at maximal hyperemia were acquired in 5 animals. Correlation coefficient between conventional mean hyperemic FFR with pressure-wire and directly measured FFR with flow-probe was 0.876 (standard error estimate=0.069; P<0.0001). The hyperemic end-diastolic FFR with pressure-wire correlated better with FFR measured directly with flow-probe (r=0.941, standard error estimate=0.050; P<0.0001). Instantaneous hyperemic ECG-gated FFR acquired at end-diastole, as compared with conventional full-cardiac cycle FFR, has an improved correlation with FFR measured directly with ultrasound flow-probe.

Surface- and tip-enhanced Raman spectroscopy reveals spin-waves in iron oxide nanoparticles

NASA Astrophysics Data System (ADS)

Rodriguez, Raul D.; Sheremet, Evgeniya; Deckert-Gaudig, Tanja; Chaneac, Corinne; Hietschold, Michael; Deckert, Volker; Zahn, Dietrich R. T.

2015-05-01

Nanomaterials have the remarkable characteristic of displaying physical properties different from their bulk counterparts. An additional degree of complexity and functionality arises when oxide nanoparticles interact with metallic nanostructures. In this context the Raman spectra due to plasmonic enhancement of iron oxide nanocrystals are here reported showing the activation of spin-waves. Iron oxide nanoparticles on gold and silver tips are found to display a band around 1584 cm-1 attributed to a spin-wave magnon mode. This magnon mode is not observed for nanoparticles deposited on silicon (111) or on glass substrates. Metal-nanoparticle interaction and the strongly localized electromagnetic field contribute to the appearance of this mode. The localized excitation that generates this mode is confirmed by tip-enhanced Raman spectroscopy (TERS). The appearance of the spin-waves only when the TERS tip is in close proximity to a nanocrystal edge suggests that the coupling of a localized plasmon with spin-waves arises due to broken symmetry at the nanoparticle border and the additional electric field confinement. Beyond phonon confinement effects previously reported in similar systems, this work offers significant insights on the plasmon-assisted generation and detection of spin-waves optically induced.Nanomaterials have the remarkable characteristic of displaying physical properties different from their bulk counterparts. An additional degree of complexity and functionality arises when oxide nanoparticles interact with metallic nanostructures. In this context the Raman spectra due to plasmonic enhancement of iron oxide nanocrystals are here reported showing the activation of spin-waves. Iron oxide nanoparticles on gold and silver tips are found to display a band around 1584 cm-1 attributed to a spin-wave magnon mode. This magnon mode is not observed for nanoparticles deposited on silicon (111) or on glass substrates. Metal-nanoparticle interaction and the strongly localized electromagnetic field contribute to the appearance of this mode. The localized excitation that generates this mode is confirmed by tip-enhanced Raman spectroscopy (TERS). The appearance of the spin-waves only when the TERS tip is in close proximity to a nanocrystal edge suggests that the coupling of a localized plasmon with spin-waves arises due to broken symmetry at the nanoparticle border and the additional electric field confinement. Beyond phonon confinement effects previously reported in similar systems, this work offers significant insights on the plasmon-assisted generation and detection of spin-waves optically induced. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr01277e

Electrostatic potential in a bent piezoelectric nanowire with consideration of size-dependent piezoelectricity and semiconducting characterization.

PubMed

Wang, K F; Wang, B L

2018-06-22

Determining the electric potential in a bent piezoelectric nanowire (NW) is a fundamental issue of nanogenerators and nanopiezotronics. The combined influence of the flexoelectric effect, the semiconducting performance and the angle of atomic force microscope (AFM) tip has never been studied previously and will be investigated in this paper. The exact solution for the electric potential of a bent piezoelectric semiconductor NW is derived. The electric potential of the present model with consideration of flexoelectric effect varies along the length of the NW and is different from that of the classical piezoelectric model. Flexoelectric effect enhances but the semiconducting performance reduces the electric potential of the NW. In addition, it is found that if the angle of the AFM tip reaches 30°, the error of the electric potential obtained from the model ignored the effect of the angle of the AFM tip is almost 16%, which is unacceptable.

Coral Reef Resilience, Tipping Points and the Strength of Herbivory

PubMed Central

Holbrook, Sally J.; Schmitt, Russell J.; Adam, Thomas C.; Brooks, Andrew J.

2016-01-01

Coral reefs increasingly are undergoing transitions from coral to macroalgal dominance. Although the functional roles of reef herbivores in controlling algae are becoming better understood, identifying possible tipping points in the herbivory-macroalgae relationships has remained a challenge. Assessment of where any coral reef ecosystem lies in relation to the coral-to-macroalgae tipping point is fundamental to understanding resilience properties, forecasting state shifts, and developing effective management practices. We conducted a multi-year field experiment in Moorea, French Polynesia to estimate these properties. While we found a sharp herbivory threshold where macroalgae escape control, ambient levels of herbivory by reef fishes were well above that needed to prevent proliferation of macroalgae. These findings are consistent with previously observed high resilience of the fore reef in Moorea. Our approach can identify vulnerable coral reef systems in urgent need of management action to both forestall shifts to macroalgae and preserve properties essential for resilience. PMID:27804977

Electrostatic potential in a bent piezoelectric nanowire with consideration of size-dependent piezoelectricity and semiconducting characterization

NASA Astrophysics Data System (ADS)

Wang, K. F.; Wang, B. L.

2018-06-01

Determining the electric potential in a bent piezoelectric nanowire (NW) is a fundamental issue of nanogenerators and nanopiezotronics. The combined influence of the flexoelectric effect, the semiconducting performance and the angle of atomic force microscope (AFM) tip has never been studied previously and will be investigated in this paper. The exact solution for the electric potential of a bent piezoelectric semiconductor NW is derived. The electric potential of the present model with consideration of flexoelectric effect varies along the length of the NW and is different from that of the classical piezoelectric model. Flexoelectric effect enhances but the semiconducting performance reduces the electric potential of the NW. In addition, it is found that if the angle of the AFM tip reaches 30°, the error of the electric potential obtained from the model ignored the effect of the angle of the AFM tip is almost 16%, which is unacceptable.

Molecular dynamics simulations of methane hydrate using polarizable force fields

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

Jiang, H.N.; Jordan, K.D.; Taylor, C.E.

2007-06-14

Molecular dynamics simulations of methane hydrate have been carried out using the polarizable AMOEBA and COS/G2 force fields. Properties calculated include the temperature dependence of the lattice constant, the OC and OO radial distribution functions, and the vibrational spectra. Both the AMOEBA and COS/G2 force fields are found to successfully account for the available experimental data, with overall somewhat better agreement with experiment being found for the AMOEBA model. Comparison is made with previous results obtained using TIP4P and SPC/E effective two-body force fields and the polarizable TIP4P-FQ force field, which allows for in-plane polarization only. Significant differences are foundmore » between the properties calculated using the TIP4P-FQ model and those obtained using the other models, indicating an inadequacy of restricting explicit polarization to in-plane onl« less

Dynamic steady-state analysis of crack propagation in rubber-like solids using an extended finite element method

NASA Astrophysics Data System (ADS)

Kroon, Martin

2012-01-01

In the present study, a computational framework for studying high-speed crack growth in rubber-like solids under conditions of plane stress and steady-state is proposed. Effects of inertia, viscoelasticity and finite strains are included. The main purpose of the study is to examine the contribution of viscoelastic dissipation to the total work of fracture required to propagate a crack in a rubber-like solid. The computational framework builds upon a previous work by the present author (Kroon in Int J Fract 169:49-60, 2011). The model was fully able to predict experimental results in terms of the local surface energy at the crack tip and the total energy release rate at different crack speeds. The predicted distributions of stress and dissipation around the propagating crack tip are presented. The predicted crack tip profiles also agree qualitatively with experimental findings.

Morphology of Er:YAG-laser-treated root surfaces

NASA Astrophysics Data System (ADS)

Keller, Ulrich; Stock, Karl; Hibst, Raimund

1997-12-01

From previous studies it could be demonstrated that an efficient ablation of dental calculus is possible using an Er:YAG laser with a special contact fiber tip. After improving of the design and the efficiency of light transmission of the contact tip laser treated tooth root surfaces were investigated due to morphological changes in comparison to conventional root scaling and planing. Surface modifications were observed histologically under the light microscope and by means of a Scanning Electron Microscope. During laser treatment the intrapulpal temperature increase was measured. The results show that the improved contact tip a microstructured surface can be generated, which shows no signs of thermal effects even when a laser pulse repetition rate of 15 Hz was used. Temperature increase was limited to 4 K at a repetition rate of 10 Hz and to 5.5 K at a repetition rate of 15 Hz.

Intramolecular bonds resolved on a semiconductor surface

NASA Astrophysics Data System (ADS)

Sweetman, Adam; Jarvis, Samuel P.; Rahe, Philipp; Champness, Neil R.; Kantorovich, Lev; Moriarty, Philip

2014-10-01

Noncontact atomic force microscopy (NC-AFM) is now routinely capable of obtaining submolecular resolution, readily resolving the carbon backbone structure of planar organic molecules adsorbed on metal substrates. Here we show that the same resolution may also be obtained for molecules adsorbed on a reactive semiconducting substrate. Surprisingly, this resolution is routinely obtained without the need for deliberate tip functionalization. Intriguingly, we observe two chemically distinct apex types capable of submolecular imaging. We characterize our tip apices by "inverse imaging" of the silicon adatoms of the Si (111)-7×7 surface and support our findings with detailed density functional theory (DFT) calculations. We also show that intramolecular resolution on individual molecules may be readily obtained at 78 K, rather than solely at 5 K as previously demonstrated. Our results suggest a wide range of tips may be capable of producing intramolecular contrast for molecules adsorbed on semiconductor surfaces, leading to a much broader applicability for submolecular imaging protocols.

Coral Reef Resilience, Tipping Points and the Strength of Herbivory.

PubMed

Holbrook, Sally J; Schmitt, Russell J; Adam, Thomas C; Brooks, Andrew J

2016-11-02

Coral reefs increasingly are undergoing transitions from coral to macroalgal dominance. Although the functional roles of reef herbivores in controlling algae are becoming better understood, identifying possible tipping points in the herbivory-macroalgae relationships has remained a challenge. Assessment of where any coral reef ecosystem lies in relation to the coral-to-macroalgae tipping point is fundamental to understanding resilience properties, forecasting state shifts, and developing effective management practices. We conducted a multi-year field experiment in Moorea, French Polynesia to estimate these properties. While we found a sharp herbivory threshold where macroalgae escape control, ambient levels of herbivory by reef fishes were well above that needed to prevent proliferation of macroalgae. These findings are consistent with previously observed high resilience of the fore reef in Moorea. Our approach can identify vulnerable coral reef systems in urgent need of management action to both forestall shifts to macroalgae and preserve properties essential for resilience.

Alarm!!! A UFO inside the heart.

PubMed

Santoro, Giuseppe; Castaldi, Biagio; Iacono, Carola; Giugno, Luca; Gaio, Gianpiero; Russo, Maria G

2012-10-01

An 8-year-old asymptomatic child was referred for surgical repair of coronary sinus atrial septal defect resulting in significant left-to-right shunt and right chamber volume overload. The septal fenestration was located near to its drainage site into the right atrium. Due to this seemingly favourable anatomy, transcatheter closure of the septal defect was performed using an Amplatzer Septal Occluder device. The echocardiographic postprocedural evaluation imaged the occluding device almost perpendicular to the atrial septum, seemingly floating above the mitral valve orifice, like an alien spaceship inside the heart.

Method of preparing sodalite from chloride salt occluded zeolite

DOEpatents

Lewis, Michele A.; Pereira, Candido

1997-01-01

A method for immobilizing waste chloride salts containing radionuclides and hazardous nuclear material for permanent disposal starting with a substantially dry zeolite and sufficient glass to form leach resistant sodalite with occluded radionuclides and hazardous nuclear material. The zeolite and glass are heated to a temperature up to about 1000.degree. K. to convert the zeolite to sodalite and thereafter maintained at a pressure and temperature sufficient to form a sodalite product near theoretical density. Pressure is used on the formed sodalite to produce the required density.

Method of preparing sodalite from chloride salt occluded zeolite

DOEpatents

Lewis, M.A.; Pereira, C.

1997-03-18

A method is described for immobilizing waste chloride salts containing radionuclides and hazardous nuclear material for permanent disposal starting with a substantially dry zeolite and sufficient glass to form leach resistant sodalite with occluded radionuclides and hazardous nuclear material. The zeolite and glass are heated to a temperature up to about 1000 K to convert the zeolite to sodalite and thereafter maintained at a pressure and temperature sufficient to form a sodalite product near theoretical density. Pressure is used on the formed sodalite to produce the required density.

Transcatheter closure of a large patent ductus arteriosus in a young child using the Amplatzer duct occluder.

PubMed

Jan, S-L; Hwang, B; Fu, Y-C; Chi, C-S

2005-01-01

The Amplatzer duct occluder (ADO) provides a safe and effective therapy for patients with moderate- to large-sized patent ductus arteriosus (PDA), but there have been few reports of transcatheter closure of very large PDAs in young children and infants. We report a successful transcatheter closure of a very large PDA, 10.5 mm in diameter at the narrowest point, with a 14/12-mm ADO. To our knowledge, this is the largest PDA ever closed by an interventional method in such a young child.

Diplopia Following Short Treatment for Moderate Amblyopia.

PubMed

Hoole, Janice; Barrow, Natasha

2017-09-01

A case of an autistic child, aged 8 years, who reported binocular diplopia following just 2 hours total occlusion per day for 6 weeks for strabismic/anisometropic amblyopia is reported. There was a history of known long-standing reduced uniocular acuity without treatment. Pretreatment Sbisa bar assessment suggested moderate suppression. The diplopia was treated over 6 months including occluding the amblyopic eye and gradually reducing the density of the occluder until fixation with the nonamblyopic eye could be maintained and diplopia ignored. Possible contributing factors are discussed.

Ultrasound-guided transhepatic puncture of the hepatic veins for TIPS placement.

PubMed

Gazzera, C; Fonio, P; Gallesio, C; Camerano, F; Doriguzzi Breatta, A; Righi, D; Veltri, A; Gandini, G

2013-04-01

This retrospective analysis was carried out to assess the feasibility and results of transjugular intrahepatic portal systemic shunt (TIPS) performed with ultrasound (US)-guided percutaneous puncture of the hepatic veins. Over a period of 3 years, 153 patients were treated with TIPS at our centre. In eight cases, a percutaneous puncture of the middle (n=7) or right (n=1) hepatic vein was required because the hepatic vein ostium was not accessible. Indications for TIPS were bleeding (n=1), Budd-Chiari syndrome (n=1), ascites (n=2), reduced portal flow (n=1) and incomplete portal thrombosis (n=3). A 0.018-in. guidewire was anterogradely introduced into the hepatic vein to the inferior vena cava (IVC) through a 21-gauge needle. In the meantime, a 25-mm snare-loop catheter was introduced through the jugular access to retrieve the guidewire, achieving through-andthrough access. Then, a Rosch-Uchida set was used to place the TIPS with the traditional technique. Technical success was achieved in all patients. There was one case of stent thrombosis. One patient died of pulmonary oedema. Three patients were eligible for liver transplantation, whereas the others were excluded due to shunt thrombosis (n=1) and previous nonhepatic neoplasms (n=3). The percutaneous approach to hepatic veins is rapid and safe and may be useful for avoiding traumatic liver injuries.

Differential enrichment of TTF-I and Tip5 in the T-like promoter structures of the rDNA contribute to the epigenetic response of Cyprinus carpio during environmental adaptation.

PubMed

Nardocci, Gino; Simonet, Nicolas G; Navarro, Cristina; Längst, Gernot; Alvarez, Marco

2016-08-01

To ensure homeostasis, ectothermic organisms adapt to environmental variations through molecular mechanisms. We previously reported that during the seasonal acclimatization of the common carp Cyprinus carpio, molecular and cellular functions are reprogrammed, resulting in distinctive traits. Importantly, the carp undergoes a drastic rearrangement of nucleolar components during adaptation. This ultrastructural feature reflects a fine modulation of rRNA gene transcription. Specifically, we identified the involvement of the transcription termination factor I (TTF-I) and Tip-5 (member of nucleolar remodeling complex, NoRC) in the control of rRNA transcription. Our results suggest that differential Tip5 enrichment is essential for silencing carp ribosomal genes and that the T0 element is key for regulating the ribosomal gene during the acclimatization process. Interestingly, the expression and content of Tip5 were significantly higher in winter than in summer. Since carp ribosomal gene expression is lower in the winter than in summer, and considering that expression concomitantly occurs with nucleolar ultrastructural changes of the acclimatization process, these results indicate that Tip5 importantly contributes to silencing the ribosomal genes. In conclusion, the current study provides novel evidence on the contributions of TTF-I and NoRC in the environmental reprogramming of ribosomal genes during the seasonal adaptation process in carp.

The Microtubule-Associated Protein MAP18 Affects ROP2 GTPase Activity during Root Hair Growth1[OPEN

PubMed Central

Kang, Erfang; Zheng, Mingzhi; Zhang, Yan; Yuan, Ming; Fu, Ying

2017-01-01

Establishment and maintenance of the polar site are important for root hair tip growth. We previously reported that Arabidopsis (Arabidopsis thaliana) MICROTUBULE-ASSOCIATED PROTEIN18 (MAP18) functions in controlling the direction of pollen tube growth and root hair elongation. Additionally, the Rop GTPase ROP2 was reported as a positive regulator of both root hair initiation and tip growth in Arabidopsis. Both loss of function of ROP2 and knockdown of MAP18 lead to a decrease in root hair length, whereas overexpression of either MAP18 or ROP2 causes multiple tips or a branching hair phenotype. However, it is unclear whether MAP18 and ROP2 coordinately regulate root hair growth. In this study, we demonstrate that MAP18 and ROP2 interact genetically and functionally. MAP18 interacts physically with ROP2 in vitro and in vivo and preferentially binds to the inactive form of the ROP2 protein. MAP18 promotes ROP2 activity during root hair tip growth. Further investigation revealed that MAP18 competes with RhoGTPase GDP DISSOCIATION INHIBITOR1/SUPERCENTIPEDE1 for binding to ROP2, in turn affecting the localization of active ROP2 in the plasma membrane of the root hair tip. These results reveal a novel function of MAP18 in the regulation of ROP2 activation during root hair growth. PMID:28314794

Real-ear-to-coupler difference predictions as a function of age for two coupling procedures.

PubMed

Bagatto, Marlene P; Scollie, Susan D; Seewald, Richard C; Moodie, K Shane; Hoover, Brenda M

2002-09-01

The predicted real-ear-to-coupler difference (RECD) values currently used in pediatric hearing instrument prescription methods are based on 12-month age range categories and were derived from measures using standard acoustic immittance probe tips. Consequently, the purpose of this study was to develop normative RECD predicted values for foam/acoustic immittance tips and custom earmolds across the age continuum. To this end, RECD data were collected on 392 infants and children (141 with acoustic immittance tips, 251 with earmolds) to develop normative regression equations for use in deriving continuous age predictions of RECDs for foam/acoustic immittance tips and earmolds. Owing to the substantial between-subject variability observed in the data, the predictive equations of RECDs by age (in months) resulted in only gross estimates of RECD values (i.e., within +/- 4.4 dB for 95% of acoustic immittance tip measures; within +/- 5.4 dB in 95% of measures with custom earmolds) across frequency. Thus, it is concluded that the estimates derived from this study should not be used to replace the more precise individual RECD measurements. Relative to previously available normative RECD values for infants and young children, however, the estimates derived through this study provide somewhat more accurate predicted values for use under those circumstances for which individual RECD measurements cannot be made.

Identification of a novel promoter from banana aquaporin family gene (MaTIP1;2) which responses to drought and salt-stress in transgenic Arabidopsis thaliana.

PubMed

Song, Shun; Xu, Yi; Huang, Dongmei; Miao, Hongxia; Liu, Juhua; Jia, Caihong; Hu, Wei; Valarezo, Ana Valeria; Xu, Biyu; Jin, Zhiqiang

2018-07-01

Drought and salt stresses often affect plant growth and crop yields. Identification of promoters involved in drought and salt stress responses is of great significance for genetic improvement of crop resistance. Our previous studies showed that aquaporin can respond to drought and salt stresses, but its promoter has not yet been reported in plants. In the present study, cis-acting elements of MaAQP family member promoters were systematically analyzed in banana. Expression of MaTIP1; 2 was induced by drought and salt stresses but not sensitive to cold stress, waterlogging stress, or mechanical damage, and its promoter contained five stress-related cis-acting elements. The MaTIP1; 2 promoter (841 bp upstream of translation initiation site) from banana (Musa acuminata L. AAA group cv. Brazilian) was isolated through genome walking polymerase chain reaction, and found to contain a TATA Box, CAAT box, ABRE element, CCGTCC box, CGTCA motif, and TCA element. Transformation of the MaTIP1; 2 promoter into Arabidopsis to assess its function indicated that it responds to both drought and salt stress treatments. These results suggest that MaTIP1; 2 utilization may improve drought and salt stresses resistance of the transgenic plants by promoting banana aquaporin expression. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

Analysis of Tip Vortices Identified in the Instantaneous Wake of a Horizontal-Axis Model Wind Turbine Placed in a Turbulent Boundary Layer

NASA Astrophysics Data System (ADS)

Jain, Akash; Mehdi, Faraz; Sheng, Jian

2014-11-01

The near-wake field, a short region characterized by the physical specifications of a turbine, is of particular interest for flow-structure interactions responsible for asymmetric loadings, premature structural breakdown, noise generation etc. Helical tip vortices constitute a distinctive feature of this region and are dependent not only on the turbine geometry but also on the incoming flow profile. High-spatial resolution PIV measurements are made in the wake of a horizontal-axis model wind turbine embedded in a neutrally stratified turbulent boundary layer. The data is acquired over consecutive locations up to 10 diameters downstream of the turbine but the focus here is on the tip vortices identified in the instantaneous fields. Contrary to previous studies, both top and bottom tip vortices are clearly distinguishable in either ensemble fields or instantaneous realizations. The streamwise extent of these vortices stretches from the turbine till they merge into the expanding mid-span wake. The similarities and differences in the top and bottom tip vortices are explored through the evolution of their statistics. In particular, the distributions of the loci of vortex cores and their circulations are compared. The information will improve our understanding of near wake vortical dynamics, provide data for model validation, and aid in the devise of flow control strategies.

Kinesins have a dual function in organizing microtubules during both tip growth and cytokinesis in Physcomitrella patens.

PubMed

Hiwatashi, Yuji; Sato, Yoshikatsu; Doonan, John H

2014-03-01

Microtubules (MTs) play a crucial role in the anisotropic deposition of cell wall material, thereby affecting the direction of growth. A wide range of tip-growing cells display highly polarized cell growth, and MTs have been implicated in regulating directionality and expansion. However, the molecular machinery underlying MT dynamics in tip-growing plant cells remains unclear. Here, we show that highly dynamic MT bundles form cyclically in the polarized expansion zone of the moss Physcomitrella patens caulonemal cells through the coalescence of growing MT plus ends. Furthermore, the plant-specific kinesins (KINID1) that are is essential for the proper MT organization at cytokinesis also regulate the turnover of the tip MT bundles as well as the directionality and rate of cell growth. The plus ends of MTs grow toward the expansion zone, and KINID1 is necessary for the stability of a single coherent focus of MTs in the center of the zone, whose formation coincides with the accumulation of KINID1. We propose that KINID-dependent MT bundling is essential for the correct directionality of growth as well as for promoting growth per se. Our findings indicate that two localized cell wall deposition processes, tip growth and cytokinesis, previously believed to be functionally and evolutionarily distinct, share common and plant-specific MT regulatory components.

2.5-month-old infants' reasoning about when objects should and should not be occluded.

PubMed

Aguiar, A; Baillargeon, R

1999-09-01

The present research examined 2.5-month-old infants' reasoning about occlusion events. Three experiments investigated infants' ability to predict whether an object should remain continuously hidden or become temporarily visible when passing behind an occluder with an opening in its midsection. In Experiment 1, the infants were habituated to a short toy mouse that moved back and forth behind a screen. Next, the infants saw two test events that were identical to the habituation event except that a portion of the screen's midsection was removed to create a large window. In one event (high-window event), the window extended from the screen's upper edge; the mouse was shorter than the bottom of the window and thus did not become visible when passing behind the screen. In the other event (low-window event), the window extended from the screen's lower edge; although the mouse was shorter than the top of the window and hence should have become fully visible when passing behind the screen, it never appeared in the window. The infants tended to look equally at the high- and low-window events, suggesting that they were not surprised when the mouse failed to appear in the low window. However, positive results were obtained in Experiment 2 when the low-window event was modified: a portion of the screen above the window was removed so that the left and right sections of the screen were no longer connected (two-screens event). The infants looked reliably longer at the two-screens than at the high-window event. Together, the results of Experiments 1 and 2 suggested that, at 2.5 months of age, infants possess only very limited expectations about when objects should and should not be occluded. Specifically, infants expect objects (1) to become visible when passing between occluders and (2) to remain hidden when passing behind occluders, irrespective of whether these have openings extending from their upper or lower edges. Experiment 3 provided support for this interpretation. The implications of these findings for models of the origins and development of infants' knowledge about occlusion events are discussed. Copyright 1999 Academic Press.

Mineral control of soil carbon storage with reforestation of abandoned pastures

NASA Astrophysics Data System (ADS)

Marín-Spiotta, E.; Silver, W. L.; Swanston, C. W.; Torn, M. S.; Burton, S. D.

2006-12-01

We applied CP MAS 13C-NMR spectroscopy and radiocarbon modeling to soil C density fractions to track changes in the quality and turnover of C with forest regrowth on former pasturelands. Our results showed that inter-aggregate, unattached particulate organic C (free light fraction) and C located inside soil aggregates (occluded light fraction) represent distinct soil C pools. The signal intensity of the O-alkyl region, representing cellulose, decreased with mineral-association, while alkyl C, attributed to waxy compounds and microbially resynthesized lipids, increased from the free to the occluded light fractions. The alkyl/O-alkyl ratio changed consistently with changes in C-to-N and δ15N across different land cover types, and thus appears to be a reliable index of humification. In contrast to cellulose, proteins, lipids and lignin did not show any consistent trends, suggesting different controls on their decomposition. Greater variability in the chemical makeup of the occluded light fraction suggests that it represents material in different stages of decay. Mean residence times (MRT) of the free light C were significantly shorter (4.3 ± 0.5 yrs) than for the occluded fraction (7.3 ± 0.8 yrs). The occluded fraction in active pastures and secondary forests in the earliest stage of succession had shorter MRT than in primary forests and older secondary forests, which would be explained by lower aggregate stability and faster cycling rates in disturbed versus undisturbed soils. The mineral associated C in the disturbed soils had slower cycling C (MRT = 98.9 ± 10.6 yrs) than the undisturbed sites (65.8 ± 2.1 yrs), most likely due to a preferential loss of labile C in the first. Incorporation of C into soil aggregates afforded some protection from decomposition, but the main mechanism of stabilization was direct mineral association. As the sorptive capacity of a soil is dependent on its mineral composition, it appears that the Oxisols at our sites have reached their maximum C storage capacity. This may explain their resiliency to land-use change and why we have observed no significant accumulation of soil C despite large increases in aboveground biomass with reforestation.

The concave cusp as a determiner of figure-ground.

PubMed

Stevens, K A; Brookes, A

1988-01-01

The tendency to interpret as figure, relative to background, those regions that are lighter, smaller, and, especially, more convex is well known. Wherever convex opaque objects abut or partially occlude one another in an image, the points of contact between the silhouettes form concave cusps, each indicating the local assignment of figure versus ground across the contour segments. It is proposed that this local geometric feature is a preattentive determiner of figure-ground perception and that it contributes to the previously observed tendency for convexity preference. Evidence is presented that figure-ground assignment can be determined solely on the basis of the concave cusp feature, and that the salience of the cusp derives from local geometry and not from adjacent contour convexity.

A comparison of the in vivo neoendothelialization and wound healing processes of three atrial septal defect occluders used during childhood in a nonrandomized prospective trial

PubMed Central

Şahin, Derya Aydın; Başpınar, Osman; Sülü, Ayşe; Karslıgil, Tekin; Kul, Seval

2017-01-01

Objective: We prospectively investigated the neoendothelialization of transcatheter secundum atrial septal defect (ASD) closure in children receiving one of three different occluders. Methods: Transcatheter ASD closure was performed for 44 children. The patients were divided into three groups: group I: Amplatzer, group II: Lifetech CeraFlex, and group III: Occlutech Figulla Flex II septal occluder. The data were prospectively analyzed. Markers of the three phases of wound healing were studied in all patients before and on the 1st and 10th days and 1st month post intervention. Results: The mean age of children was 7.08±3.51 years, and the mean weight was 26.07±15.07 kg. The mean ASD diameter was 12.65±3.50 mm. Groups I, II, and III comprised 34.1%, 31.8%, and 34.1% patients, respectively. No significant differences were observed between the groups regarding patient number, age, defect size, device diameter, or total septum/device ratio (p>0.05). Inflammatory and proliferative phase marker levels increased following the procedure (p<0.05). However, scar formation markers did not change after 1 month. No significant differences in neoendothelializaton were observed among the different occluders (p>0.05). Conclusion: All three devices were composed of nitinol with different surface coating techniques. Although the different manufacturing features were claimed to facilitate of neoendothelialization, no differences were observed among the three devices 1 month following the procedure. PMID:28761023

Identifying the Optimal Water-Occluding Earplugs: A Scientific Simulation Study.

PubMed

Kovoor, Joshua; Al Hussaini, Ali; Backhouse, Steven

2016-12-01

Numerous types of water-occluding earplugs are available as a means of preventing infection in patients with external and middle ear disease. However, little is known about the comparative efficacies of these earplugs with prolonged water exposure. In this study, we assessed the water impermeability of various earplug materials to prolonged water exposure. Nine earplugs were tested: cotton wool mixed with petroleum jelly, cotton wool externally coated with petroleum jelly, Blu-Tack, foam earplugs, silicone putty, silicone earplugs, flanged earplugs, and hard and soft silicone custom-moulds. Precision-engineered cups were filled with 30 mL water and sealed with lids that contained a 10 mm diameter hole to simulate the ear canal. The aperture was occluded with different earplugs, and the cup was inverted. Computer software was used to record the water loss to the nearest 10 milligrams 720 times over a three-hour period. The test was repeated five times for each material. The water permeability onset, rate, and total amount of water loss varied markedly between the materials; cotton wool mixed with petroleum jelly demonstrated the fastest onset of leak and the highest rate of water loss (p < 0.00001), as well as the largest amount of cumulative water loss (p = 0.00213). The soft silicone custom-mould plugs, hard silicone custom-mould plugs, foam plugs, and silicone putty demonstrated no leaks. This study demonstrates a wide range of water permeabilities of commonly used ear-occluding materials during prolonged water exposure. We found that the generally suggested regimen of cotton wool mixed with petroleum jelly may be inefficacious for substantial periods of water exposure.

Association between autistic traits and emotion adaptation to partially occluded faces.

PubMed

Luo, Chengwen; Burns, Edwin; Xu, Hong

2017-04-01

Prolonged exposure to a happy face makes subsequently presented faces appear sadder: the facial emotion aftereffect (FEA). People with autism spectrum disorders and their relatives have diminished holistic perception of faces. Levels of autism can be measured continuously in the general population by autistic traits using the autism-quotient (AQ). Prior work has not found any association between AQ and FEA in adults, possibly due to non-holistic processing strategies employed by those at the higher end of the spectrum. In the present study, we tested whether AQ was associated with FEA to partially occluded faces. We hypothesized that inferring emotion from such faces would require participants to process their viewable parts as a gestalt percept, thus we anticipated this ability would diminish as autistic traits increased. In Experiment 1, we partially occluded the adapting faces with aligned or misaligned opaque bars. Both conditions produced significant FEAs, with aftereffects and AQ negatively correlated. In Experiment 2, we adapted participants to obscured faces flickering in luminance, and manipulated the facilitation of holistic perception by varying the synchronization of this flickering. We found significant FEAs in all conditions, but abolished its association with AQ. In Experiment 3, we showed that the association between AQ and FEA in the occluded conditions in Experiment 1 was not due to the recognizability or perceived emotional intensity of our adaptors; although the overall FEAs were linked to emotional intensity. We propose that increasing autistic traits are associated with diminishing abilities in perceiving emotional faces as a gestalt percept. Copyright © 2017 Elsevier Ltd. All rights reserved.

Contributions of retinal input and phenomenal representation of a fixation object to the saccadic gap effect.

PubMed

Ueda, Hiroshi; Takahashi, Kohske; Watanabe, Katsumi

2013-04-19

The saccadic "gap effect" refers to a phenomenon whereby saccadic reaction times (SRTs) are shortened by the removal of a visual fixation stimulus prior to target presentation. In the current study, we investigated whether the gap effect was influenced by retinal input of a fixation stimulus, as well as phenomenal permanence and/or expectation of the re-emergence of a fixation stimulus. In Experiment 1, we used an occluded fixation stimulus that was gradually hidden by a moving plate prior to the target presentation, which produced the impression that the fixation stimulus still remained and would reappear from behind the plate. We found that the gap effect was significantly weakened with the occluded fixation stimulus. However, the SRT with the occluded fixation stimulus was still shorter in comparison to when the fixation stimulus physically remained on the screen. In Experiment 2, we investigated whether this effect was due to phenomenal maintenance or expectation of the reappearance of the fixation stimulus; this was achieved by using occluding plates that were an identical color to the background screen, giving the impression of reappearance of the fixation stimulus but not of its maintenance. The result showed that the gap effect was still weakened by the same degree even without phenomenal maintenance of the fixation stimulus. These results suggest that the saccadic gap effect is modulated by both retinal input and subjective expectation of re-emergence of the fixation stimulus. In addition to oculomotor mechanisms, other components, such as attentional mechanisms, likely contribute to facilitation of the subsequent action. Copyright © 2013 Elsevier Ltd. All rights reserved.

[Lung perfusion studies after percutaneous closure of patent ductus arteriosus using the Amplatzer Duct Occluder in children].

PubMed

Parra-Bravo, José Rafael; Apolonio-Martínez, Adriana; Estrada-Loza, María de Jesús; Beirana-Palencia, Luisa Gracia; Ramírez-Portillo, César Iván

2015-01-01

The closure of patent ductus arteriosus with multiple devices has been associated with a reduction in lung perfusion. We evaluated the pulmonary perfusion after percutaneous closure of patent ductus arteriosus with the Amplatzer Duct Occluder device using perfusion lung scan. Thirty patients underwent successful percutaneous patent ductus arteriosus occlusions using the Amplatzer Duct Occluder device were included in this study. Lung perfusion scans were preformed 6 months after the procedure. Peak flow velocities and protrusion of the device were analyzed by Doppler echocardiography. A left lung perfusion<40% was considered abnormal. The device implantation was successful in all patients. Average perfusion of left lung was 44.7±4.9% (37.8-61.4). Five patients (16.6%) showed decreased perfusion of the left lung. Age, low weight, the length of the ductus arteriosus and the minimum and maximum diameter/length of the ductus arteriosus ratio were statistically significant in patients with abnormalities of lung perfusion. It was observed protrusion the device in 6 patients with a higher maximum flow rate in the left pulmonary artery. The left lung perfusion may be compromised after percutaneous closure of patent ductus arteriosus with the Amplatzer Duct Occluder. The increased flow velocity in the origin of the left pulmonary artery can be a poor indicator of reduction in pulmonary perfusion and can occur in the absence of protrusion of the device. Copyright © 2014 Instituto Nacional de Cardiología Ignacio Chávez. Published by Masson Doyma México S.A. All rights reserved.

Paravertebral block catheter breakage by electrocautery during thoracic surgery.

PubMed

Saeki, Noboru; Sugimoto, Yuki; Mori, Yoko; Kato, Takahiro; Miyoshi, Hirotsugu; Nakamura, Ryuji; Koga, Tomomichi

2017-06-01

Advantages of thoracic paravertebral analgesia (TPA) include placement of the catheter closer to the surgical field; however, the catheter can become damaged during the operation. We experienced a case of intraoperative TPA catheter breakage that prompted us to perform an experiment to investigate possible causes. A 50-year-old male underwent a thoracoscopic lower lobectomy under general anesthesia with TPA via an intercostal approach. Following surgery, it was discovered that the catheter had become occluded, as well as cut and fused, so we reopened the incision and removed the residual catheter. From that experience, we performed an experiment to examine electrocautery-induced damage in normal (Portex™, Smith's Medical), radiopaque (Perifix SoftTip™, BBraun), and reinforced (Perifix FX™, BBraun) epidural catheters (n = 8 each). Chicken meat was penetrated by each catheter and then cut by electrocautery. In the normal group, breakage occurred in 8 and occlusion in 6 of the catheters, and in the radiopaque group breakage occurred in 8 and occlusion in 7. In contrast, breakage occurred in only 3 and occlusion in none in the reinforced group, with the 5 without breakage remaining connected only by the spring coil. Furthermore, in 7 of the reinforced catheters, electric arc-induced thermal damage was observed at the tip of the catheter. A TPA catheter for thoracic surgery should be inserted via the median approach, or it should be inserted after surgery to avoid catheter damage during surgery.

Regulation of Cortical Dynamic Range by Background Synaptic Noise and Feedforward Inhibition

PubMed Central

Khubieh, Ayah; Ratté, Stéphanie; Lankarany, Milad; Prescott, Steven A.

2016-01-01

The cortex encodes a broad range of inputs. This breadth of operation requires sensitivity to weak inputs yet non-saturating responses to strong inputs. If individual pyramidal neurons were to have a narrow dynamic range, as previously claimed, then staggered all-or-none recruitment of those neurons would be necessary for the population to achieve a broad dynamic range. Contrary to this explanation, we show here through dynamic clamp experiments in vitro and computer simulations that pyramidal neurons have a broad dynamic range under the noisy conditions that exist in the intact brain due to background synaptic input. Feedforward inhibition capitalizes on those noise effects to control neuronal gain and thereby regulates the population dynamic range. Importantly, noise allows neurons to be recruited gradually and occludes the staggered recruitment previously attributed to heterogeneous excitation. Feedforward inhibition protects spike timing against the disruptive effects of noise, meaning noise can enable the gain control required for rate coding without compromising the precise spike timing required for temporal coding. PMID:26209846

A deforestation-induced tipping point for the South American monsoon system.

PubMed

Boers, Niklas; Marwan, Norbert; Barbosa, Henrique M J; Kurths, Jürgen

2017-01-25

The Amazon rainforest has been proposed as a tipping element of the earth system, with the possibility of a dieback of the entire ecosystem due to deforestation only of parts of the rainforest. Possible physical mechanisms behind such a transition are still subject to ongoing debates. Here, we use a specifically designed model to analyse the nonlinear couplings between the Amazon rainforest and the atmospheric moisture transport from the Atlantic to the South American continent. These couplings are associated with a westward cascade of precipitation and evapotranspiration across the Amazon. We investigate impacts of deforestation on the South American monsoonal circulation with particular focus on a previously neglected positive feedback related to condensational latent heating over the rainforest, which strongly enhances atmospheric moisture inflow from the Atlantic. Our results indicate the existence of a tipping point. In our model setup, crossing the tipping point causes precipitation reductions of up to 40% in non-deforested parts of the western Amazon and regions further downstream. The responsible mechanism is the breakdown of the aforementioned feedback, which occurs when deforestation reduces transpiration to a point where the available atmospheric moisture does not suffice anymore to release the latent heat needed to maintain the feedback.

A deforestation-induced tipping point for the South American monsoon system

PubMed Central

Boers, Niklas; Marwan, Norbert; Barbosa, Henrique M. J.; Kurths, Jürgen

2017-01-01

The Amazon rainforest has been proposed as a tipping element of the earth system, with the possibility of a dieback of the entire ecosystem due to deforestation only of parts of the rainforest. Possible physical mechanisms behind such a transition are still subject to ongoing debates. Here, we use a specifically designed model to analyse the nonlinear couplings between the Amazon rainforest and the atmospheric moisture transport from the Atlantic to the South American continent. These couplings are associated with a westward cascade of precipitation and evapotranspiration across the Amazon. We investigate impacts of deforestation on the South American monsoonal circulation with particular focus on a previously neglected positive feedback related to condensational latent heating over the rainforest, which strongly enhances atmospheric moisture inflow from the Atlantic. Our results indicate the existence of a tipping point. In our model setup, crossing the tipping point causes precipitation reductions of up to 40% in non-deforested parts of the western Amazon and regions further downstream. The responsible mechanism is the breakdown of the aforementioned feedback, which occurs when deforestation reduces transpiration to a point where the available atmospheric moisture does not suffice anymore to release the latent heat needed to maintain the feedback. PMID:28120928

Spatially discrete thermal drawing of biodegradable microneedles for vascular drug delivery.

PubMed

Choi, Chang Kuk; Lee, Kang Ju; Youn, Young Nam; Jang, Eui Hwa; Kim, Woong; Min, Byung-Kwon; Ryu, WonHyoung

2013-02-01

Spatially discrete thermal drawing is introduced as a novel method for the fabrication of biodegradable microneedles with ultra-sharp tip ends. This method provides the enhanced control of microneedle shapes by spatially controlling the temperature of drawn polymer as well as drawing steps and speeds. Particular focus is given on the formation of sharp tip ends of microneedles at the end of thermal drawing. Previous works relied on the fracture of polymer neck by fast drawing that often causes uncontrolled shapes of microneedle tips. Instead, this approach utilizes the surface energy of heated polymer to form ultra-sharp tip ends. We have investigated the effect of such temperature control, drawing speed, and drawing steps in thermal drawing process on the final shape of microneedles using biodegradable polymers. XRD analysis was performed to analyze the effect of thermal cycle on the biodegradable polymer. Load-displacement measurement also showed the dependency of mechanical strengths of microneedles on the microneedle shapes. Ex vivo vascular tissue insertion and drug delivery demonstrated microneedle insertion to tunica media layer of canine aorta and drug distribution in the tissue layer. Copyright © 2012 Elsevier B.V. All rights reserved.

Spastin, atlastin, and ER relocalization are involved in axon but not dendrite regeneration

PubMed Central

Rao, Kavitha; Stone, Michelle C.; Weiner, Alexis T.; Gheres, Kyle W.; Zhou, Chaoming; Deitcher, David L.; Levitan, Edwin S.; Rolls, Melissa M.

2016-01-01

Mutations in >50 genes, including spastin and atlastin, lead to hereditary spastic paraplegia (HSP). We previously demonstrated that reduction of spastin leads to a deficit in axon regeneration in a Drosophila model. Axon regeneration was similarly impaired in neurons when HSP proteins atlastin, seipin, and spichthyin were reduced. Impaired regeneration was dependent on genetic background and was observed when partial reduction of HSP proteins was combined with expression of dominant-negative microtubule regulators, suggesting that HSP proteins work with microtubules to promote regeneration. Microtubule rearrangements triggered by axon injury were, however, normal in all genotypes. We examined other markers to identify additional changes associated with regeneration. Whereas mitochondria, endosomes, and ribosomes did not exhibit dramatic repatterning during regeneration, the endoplasmic reticulum (ER) was frequently concentrated near the tip of the growing axon. In atlastin RNAi and spastin mutant animals, ER accumulation near single growing axon tips was impaired. ER tip concentration was observed only during axon regeneration and not during dendrite regeneration. In addition, dendrite regeneration was unaffected by reduction of spastin or atlastin. We propose that the HSP proteins spastin and atlastin promote axon regeneration by coordinating concentration of the ER and microtubules at the growing axon tip. PMID:27605706

Load-Dependent Friction Hysteresis on Graphene.

PubMed

Ye, Zhijiang; Egberts, Philip; Han, Gang Hee; Johnson, A T Charlie; Carpick, Robert W; Martini, Ashlie

2016-05-24

Nanoscale friction often exhibits hysteresis when load is increased (loading) and then decreased (unloading) and is manifested as larger friction measured during unloading compared to loading for a given load. In this work, the origins of load-dependent friction hysteresis were explored through atomic force microscopy (AFM) experiments of a silicon tip sliding on chemical vapor deposited graphene in air, and molecular dynamics simulations of a model AFM tip on graphene, mimicking both vacuum and humid air environmental conditions. It was found that only simulations with water at the tip-graphene contact reproduced the experimentally observed hysteresis. The mechanisms underlying this friction hysteresis were then investigated in the simulations by varying the graphene-water interaction strength. The size of the water-graphene interface exhibited hysteresis trends consistent with the friction, while measures of other previously proposed mechanisms, such as out-of-plane deformation of the graphene film and irreversible reorganization of the water molecules at the shearing interface, were less correlated to the friction hysteresis. The relationship between the size of the sliding interface and friction observed in the simulations was explained in terms of the varying contact angles in front of and behind the sliding tip, which were larger during loading than unloading.

A deforestation-induced tipping point for the South American monsoon system

NASA Astrophysics Data System (ADS)

Boers, Niklas; Marwan, Norbert; Barbosa, Henrique M. J.; Kurths, Jürgen

2017-01-01

The Amazon rainforest has been proposed as a tipping element of the earth system, with the possibility of a dieback of the entire ecosystem due to deforestation only of parts of the rainforest. Possible physical mechanisms behind such a transition are still subject to ongoing debates. Here, we use a specifically designed model to analyse the nonlinear couplings between the Amazon rainforest and the atmospheric moisture transport from the Atlantic to the South American continent. These couplings are associated with a westward cascade of precipitation and evapotranspiration across the Amazon. We investigate impacts of deforestation on the South American monsoonal circulation with particular focus on a previously neglected positive feedback related to condensational latent heating over the rainforest, which strongly enhances atmospheric moisture inflow from the Atlantic. Our results indicate the existence of a tipping point. In our model setup, crossing the tipping point causes precipitation reductions of up to 40% in non-deforested parts of the western Amazon and regions further downstream. The responsible mechanism is the breakdown of the aforementioned feedback, which occurs when deforestation reduces transpiration to a point where the available atmospheric moisture does not suffice anymore to release the latent heat needed to maintain the feedback.

Computational analysis of hypersonic flows past elliptic-cone waveriders

NASA Technical Reports Server (NTRS)

Yoon, Bok-Hyun; Rasmussen, Maurice L.

1991-01-01

A comprehensive study for the inviscid numerical calculation of the hypersonic flow past a class of elliptic-cone derived waveriders is presented. The theoretical background associated with hypersonic small-disturbance theory (HSDT) is reviewed. Several approximation formulas for the waverider compression surface are established. A CFD algorithm is used to calculate flow fields for the on-design case and a variety of off-design cases. The results are compared with HSDT, experiment, and other available CFD results. For the waverider shape used in previous investigations, the bow shock for the on-design condition stands off from the leading-edge tip of the waverider. It was found that this occurs because the tip was too thick according to the approximating shape formula that was used to describe the compression surface. When this was corrected, the bow shock became closer to attached as it should be. At Mach numbers greater than the design condition, a lambda-shock configuration develops near the tip of the compression surface. At negative angles of attack, other complicated shock patterns occur near the leading-edge tip. These heretofore unknown flow patterns show the power and utility of CFD for investigating novel hypersonic configurations such as waveriders.

NOTCH1 Inhibits Activation of ATM by Impairing the Formation of an ATM-FOXO3a-KAT5/Tip60 Complex.

PubMed

Adamowicz, Marek; Vermezovic, Jelena; d'Adda di Fagagna, Fabrizio

2016-08-23

The DNA damage response (DDR) signal transduction pathway is responsible for sensing DNA damage and further relaying this signal into the cell. ATM is an apical DDR kinase that orchestrates the activation and the recruitment of downstream DDR factors to induce cell-cycle arrest and repair. We have previously shown that NOTCH1 inhibits ATM activation upon DNA damage, but the underlying mechanism remains unclear. Here, we show that NOTCH1 does not impair ATM recruitment to DNA double-strand breaks (DSBs). Rather, NOTCH1 prevents binding of FOXO3a and KAT5/Tip60 to ATM through a mechanism in which NOTCH1 competes with FOXO3a for ATM binding. Lack of FOXO3a binding to ATM leads to the loss of KAT5/Tip60 association with ATM. Moreover, expression of NOTCH1 or depletion of ATM impairs the formation of the FOXO3a-KAT5/Tip60 protein complex. Finally, we show that pharmacological induction of FOXO3a nuclear localization sensitizes NOTCH1-driven cancers to DNA-damage-induced cell death. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Walking Tips for Older Adults

MedlinePlus

... A Print Share Glossary previous page Related Topics Balance Problems Falls Prevention Foot Problems Physical Activity Related Documents PDF ... you? strengthen muscles help prevent weight gain lower risks of heart disease, stroke, diabetes, ... balance lower the likelihood of falling If it’s been ...

Teaching Typography.

ERIC Educational Resources Information Center

Communication: Journalism Education Today, 1998

1998-01-01

Outlines nine objectives students should be able to accomplish after completing the activities in the unit on typography presented in the previous articles in this journal. Offers eight tips for teaching typography. Includes a short list of books about typography and a list of seven organizations. (SR)

MC-1 LOX Pump Rotating Cavitation: Issue and Investigation

NASA Technical Reports Server (NTRS)

VanHooser, Katherine; Turner, J. (Technical Monitor)

2001-01-01

Leading edge tip deformation was noted on the LOX inducer from the component test unit at disassembly. The damage was in a location similar to a previous Fastrac water flow inducer failure. A team was formed to investigate the anomaly.

The localization of occluded matrix proteins in calcareous spicules of sea urchin larvae.

PubMed

Seto, Jong; Zhang, Yang; Hamilton, Patricia; Wilt, Fred

2004-10-01

The sea urchin embryo forms calcareous endoskeletal spicules composed of calcite and an occluded protein matrix. Though the latter is approximately 0.1% of of the mass, the composite has substantially altered material properties, e.g., conchoidal fracture planes and increased hardness. Experiments were conducted to examine the localization of matrix proteins occluded in the mineral by use of immunocytochemistry coupled with scanning electron microscopy (SEM). The isolated, unfixed spicules were etched under relatively gentle conditions and exposed to affinity purified antibodies made against two different matrix proteins, as well as an antibody to the entire constellation of matrix proteins. Immunogold tagged secondary antibody was used to observe antibody localization in the back scatter mode of SEM. All proteins examined were very widely distributed throughout the calcite, supporting a model of the structure in which a multiprotein assemblage is woven with fine texture around microcrystalline domains of calcite. Gentle etching revealed a laminar arrangement of calcite solubility, consistent with a stepwise deposition of matrix and mineral to increase girth of the spicule.

No Relation between Body Temperature and Arterial Recanalization at Three Days in Patients with Acute Ischaemic Stroke.

PubMed

Geurts, Marjolein; van der Worp, H Bart; Horsch, Alexander D; Kappelle, L Jaap; Biessels, Geert J; Velthuis, Birgitta K

2015-01-01

Recanalization of an occluded intracranial artery is influenced by temperature-dependent enzymes, including alteplase. We assessed the relation between body temperature on admission and recanalization. We included 278 patients with acute ischaemic stroke within nine hours after symptom onset, who had an intracranial arterial occlusion on admission CT angiography, in 13 participating centres. We calculated the relation per every 0.1°Celsius increase in admission body temperature and recanalization at three days. Recanalization occurred in 80% of occluded arteries. There was no relation between body temperature and recanalization at three days after adjustments for age, NIHSS score on admission and treatment with alteplase (adjusted odds ratio per 0.1°Celsius, 0.99; 95% confidence interval, 0.94-1.05; p = 0.70). Results for patients treated or not treated with alteplase were essentially the same. Our findings suggest that in patients with acute ischaemic stroke there is no relation between body temperature on admission and recanalization of an occluded intracranial artery three days later, irrespective of treatment with alteplase.

No Relation between Body Temperature and Arterial Recanalization at Three Days in Patients with Acute Ischaemic Stroke

PubMed Central

Geurts, Marjolein; van der Worp, H. Bart; Horsch, Alexander D.; Kappelle, L. Jaap; Biessels, Geert J.; Velthuis, Birgitta K.

2015-01-01

Background Recanalization of an occluded intracranial artery is influenced by temperature-dependent enzymes, including alteplase. We assessed the relation between body temperature on admission and recanalization. Methods We included 278 patients with acute ischaemic stroke within nine hours after symptom onset, who had an intracranial arterial occlusion on admission CT angiography, in 13 participating centres. We calculated the relation per every 0.1°Celsius increase in admission body temperature and recanalization at three days. Results Recanalization occurred in 80% of occluded arteries. There was no relation between body temperature and recanalization at three days after adjustments for age, NIHSS score on admission and treatment with alteplase (adjusted odds ratio per 0.1°Celsius, 0.99; 95% confidence interval, 0.94–1.05; p = 0.70). Results for patients treated or not treated with alteplase were essentially the same. Conclusions Our findings suggest that in patients with acute ischaemic stroke there is no relation between body temperature on admission and recanalization of an occluded intracranial artery three days later, irrespective of treatment with alteplase. PMID:26473959

Tracking with occlusions via graph cuts.

PubMed

Papadakis, Nicolas; Bugeau, Aurélie

2011-01-01

This work presents a new method for tracking and segmenting along time-interacting objects within an image sequence. One major contribution of the paper is the formalization of the notion of visible and occluded parts. For each object, we aim at tracking these two parts. Assuming that the velocity of each object is driven by a dynamical law, predictions can be used to guide the successive estimations. Separating these predicted areas into good and bad parts with respect to the final segmentation and representing the objects with their visible and occluded parts permit handling partial and complete occlusions. To achieve this tracking, a label is assigned to each object and an energy function representing the multilabel problem is minimized via a graph cuts optimization. This energy contains terms based on image intensities which enable segmenting and regularizing the visible parts of the objects. It also includes terms dedicated to the management of the occluded and disappearing areas, which are defined on the areas of prediction of the objects. The results on several challenging sequences prove the strength of the proposed approach.

Plasma lactate concentrations and blood gas values in dogs undergoing surgical attenuation of a single congenital portosystemic shunt.

PubMed

Cariou, M P; Lipscomb, V J; Hughes, D; Brodbelt, D; Brockman, D J

2009-08-22

Plasma concentration of lactate and the values of pH, pO(2) and pCO(2) were measured in the portal, systemic venous and, when possible, systemic arterial blood of 31 dogs with a single congenital portosystemic shunt, before and shortly after the temporary complete occlusion of the shunt, and at the end of surgery. At completion of the surgery, the shunt in 16 of the dogs had been occluded completely whereas in the other 15 it had been occluded only partially. There were no significant differences between any of the measurements of these variables in the portal venous, systemic venous or arterial plasma of any of the dogs, or between the values measured in the groups in which the shunts had been occluded completely or partially. Furthermore, there were no significant differences between the two groups of dogs in the arteriovenous gradients calculated at any of the sampling sites or sampling times. None of the variables was associated with the development of postoperative complications.

Central venous access devices: an investigation of oncology nurses' troubleshooting techniques.

PubMed

Mason, Tina M; Ferrall, Sheila M; Boyington, Alice R; Reich, Richard R

2014-08-01

Experienced oncology nurses use different troubleshooting techniques for clearing occluded central venous access devices (CVADs) with varying degrees of success. The purpose of this study was to explore troubleshooting techniques used for clearing occluded CVADs by experienced oncology RNs and identify the perceived effectiveness of each technique. An invitation for a web-based survey was sent to select RN members of the Oncology Nursing Society. All nurses (N = 224) reported asking patients to raise and/or move their arm. Most nurses asked patients to lie down, cough, and take deep breaths. Respondents considered instilling a thrombolytic agent to be the most effective technique. No associations were found between techniques and respondents' years in oncology nursing, work setting, certification, or academic degree. The findings contribute to knowledge about care of patients with occluded devices and will help formulate direction for additional investigation of CVADs. Establishing the appropriateness of practice-related troubleshooting techniques may eliminate unnecessary steps and save nursing time. Educating nurses on the topic will also help reduce techniques that are not expected to yield results or are contraindicated.

[Retrospective analysis of patients with thrombocytopenia after patent ductus arteriosus interventional occlusion].

PubMed

Liao, Qi-wei; Zhang, Wei-hua; Guang, Xue-feng; Lu, Yi-bing

2013-03-01

To explore the risk factors of patent ductus arteriosus (PDA) patients with thrombocytopenia after PDA interventional occlusion. Thrombocytopenia occurred in 14 out of 350 patients underwent PDA occlusion. Age, gender, body weight, PDA size, occluder size, mean pulmonary arterial pressure, the dose of heparin, the manufacturer of occluder, residual shunt after operation were analyzed. The recovery time of different grades of thrombocytopenia was observed. Multivariate logistic regression showed that the PDA size (OR = 2.238, P < 0.05), the dose of heparin (OR = 3.247, P < 0.05), residual shunt after operation (OR = 1.912, P < 0.01) were the independent risk factors of thrombocytopenia after PDA occlusion. The recovery time of mild thrombocytopenia was (7 ± 2) days without treatment. The recovery time of moderate thrombocytopenia was (12 ± 4) days with glucocorticoids treatment. The recovery time of severe thrombocytopenia was (21 ± 7) days with platelet transfusion. The occluder size, dose of heparin, residual shunt are the independent risk factors of thrombocytopenia after PDA interventional occlusion. Recover time of thrombocytopenia after PDA interventional occlusion is closely related to the severity of thrombocytopenia.

Detecting occlusion inside a ventricular catheter using photoacoustic imaging through skull

NASA Astrophysics Data System (ADS)

Tavakoli, Behnoosh; Guo, Xiaoyu; Taylor, Russell H.; Kang, Jin U.; Boctor, Emad M.

2014-03-01

Ventricular catheters are used to treat hydrocephalus by diverting the excess of the cerebrospinal fluid (CSF) to the reabsorption site so as to regulate the intracranial pressure. The failure rate of these shunts is extremely high due to the ingrown tissue that blocks the CSF flow. We have studied a method to image the occlusion inside the shunt through the skull. In this approach the pulsed laser light coupled to the optical fiber illuminate the occluding tissue inside the catheter and an external ultrasound transducer is applied to detect the generated photoacoustic signal. The feasibility of this method is investigated using a phantom made of ovis aries brain tissue and adult human skull. We were able to image the target inside the shunt located 20mm deep inside the brain through about 4mm thick skull bone. This study could lead to the development of a simple, safe and non-invasive device for percutaneous restoration of patency to occluded shunts. This will eliminate the need of the surgical replacement of the occluded catheters which expose the patients to risks including hemorrhage and brain injury.

Test-retest reliability of probe-microphone verification in children fitted with open and closed hearing aid tips.

PubMed

Kim, Hannah; Ricketts, Todd A

2013-01-01

To investigate the test-retest reliability of real-ear aided response (REAR) measures in open and closed hearing aid fittings in children using appropriate probe-microphone calibration techniques (stored equalization for open fittings and concurrent equalization for closed fittings). Probe-microphone measurements were completed for two mini-behind-the-ear (BTE) hearing aids which were coupled to the ear using open and closed eartips via thin (0.9 mm) tubing. Before probe-microphone testing, the gain of each of the test hearing aids was programmed using an artificial ear simulator (IEC 711) and a Knowles Electronic Manikin for Acoustic Research to match the National Acoustic Laboratories-Non-Linear, version 1 targets for one of two separate hearing loss configurations using an Audioscan Verifit. No further adjustments were made, and the same amplifier gain was used within each hearing aid across both eartip configurations and all participants. Probe-microphone testing included real-ear occluded response (REOR) and REAR measures using the Verifit's standard speech signal (the carrot passage) presented at 65 dB sound pressure level (SPL). Two repeated probe-microphone measures were made for each participant with the probe-tube and hearing aid removed and repositioned between each trial in order to assess intrasubject measurement variability. These procedures were repeated using both open and closed domes. Thirty-two children, ages ranging from 4 to 14 yr. The test-retest standard deviations for open and closed measures did not exceed 4 dB at any frequency. There was also no significant difference between the open (stored equalization) and closed (concurrent equalization) methods. Reliability was particularly similar in the high frequencies and was also quite similar to that reported in previous research. There was no correlation between reliability and age, suggesting high reliability across all ages evaluated. The findings from this study suggest that reliable probe-microphone measurements are obtainable on children 4 yr and older for both traditional unvented and open-canal hearing aid fittings. These data suggest that clinicians should not avoid fitting open technology to children as young as 4 y because of concerns regarding the reliability of verification techniques. American Academy of Audiology.

Device for removing foreign objects from anatomic organs

NASA Technical Reports Server (NTRS)

Angulo, Earl D. (Inventor)

1992-01-01

A device is disclosed for removing foreign objects from anatomic organs such as the ear canal or throat. It has a housing shaped like a flashlight, an electrical power source such as a battery or AC power from a wall socket, and a tip extending from the housing. The tip has at least one wire loop made from a shape-memory-effect alloy, such as Nitinol, switchably connected to the electrical power source such that when electric current flows through the wire loop the wire loop heats up and returns to a previously programmed shape such as a curet or tweezers so as to facilitate removal of the foreign object.

Feature point based 3D tracking of multiple fish from multi-view images

PubMed Central

Qian, Zhi-Ming

2017-01-01

A feature point based method is proposed for tracking multiple fish in 3D space. First, a simplified representation of the object is realized through construction of two feature point models based on its appearance characteristics. After feature points are classified into occluded and non-occluded types, matching and association are performed, respectively. Finally, the object's motion trajectory in 3D space is obtained through integrating multi-view tracking results. Experimental results show that the proposed method can simultaneously track 3D motion trajectories for up to 10 fish accurately and robustly. PMID:28665966

Fine alignment of a large segmented mirror

NASA Technical Reports Server (NTRS)

Dey, Thomas William (Inventor)

2010-01-01

A system for aligning a segmented mirror includes a source of radiation directed along a first axis to the segmented mirror and a beamsplitter removably inserted along the first axis for redirecting radiation from the first axis to a second axis, substantially perpendicular to the first axis. An imaging array is positioned along the second axis for imaging the redirected radiation, and a knife-edge configured for cutting the redirected radiation is serially positioned to occlude and not occlude the redirected radiation, effectively providing a variable radiation pattern detected by the imaging array for aligning the segmented mirror.

Feature point based 3D tracking of multiple fish from multi-view images.

PubMed

Qian, Zhi-Ming; Chen, Yan Qiu

2017-01-01

A feature point based method is proposed for tracking multiple fish in 3D space. First, a simplified representation of the object is realized through construction of two feature point models based on its appearance characteristics. After feature points are classified into occluded and non-occluded types, matching and association are performed, respectively. Finally, the object's motion trajectory in 3D space is obtained through integrating multi-view tracking results. Experimental results show that the proposed method can simultaneously track 3D motion trajectories for up to 10 fish accurately and robustly.

Current status of percutaneous coronary intervention of chronic total occlusion

PubMed Central

Ge, Jun-bo

2012-01-01

This paper describes the current status of percutaneous coronary intervention (PCI) for totally occluded coronary arteries. Chronic total occlusion is associated with 10%–20% of all PCI procedures. Results show that opening an occluded vessel, especially one supplying a considerable area of myocardium, may be beneficial for a patient’s angina relief and heart function. We describe the devices used currently in re-canalization such as new wires, microcatheters (including Tonus and Cosair) and intravascular ultrasound guidance. Different techniques to improve the success rate and reduce complications are discussed in detail. PMID:22843178

Electrolysis-needle cauterization of corneal vessels in patients with lipid keratopathy.

PubMed

Wertheim, Michael S; Cook, Stuart D; Knox-Cartwright, Nathaniel E; Van, Dung Le; Tole, Derek M

2007-02-01

To describe a technique of corneal vessel occlusion by using electrolysis-needle cautery. A prospective case series of three patients. Corneal vessels were successfully occluded in all patients. Vessels remained occluded during the first 8 months post-cautery follow up. Two patients needed repeat cautery at 9 and 10 months respectively. Patients found the procedure comfortable. There was no post-operative induced astigmatism. The technique of ENC is simple, effective and controlled. This technique compares favorably and may prove to be more versatile than Fine Needle Diathermy in the occlusion of corneal vessels that lead to lipid keratopathy.

Helping Your Child through Early Adolescence -- Helping Your Child Series

MedlinePlus

... Bibliography Acknowledgements Tips to Help Your Child through Early Adolescence No Child Left Behind < Previous page | ^ Top ^ | Next page > Printable ... Information About... Transforming Teaching Family and Community Engagement Early Learning Helping Your Child Our mission is to promote student achievement and ...

Novel fiber optic tip designs and devices for laser surgery

NASA Astrophysics Data System (ADS)

Hutchens, Thomas Clifton

Fiber optic delivery of laser energy has been used for years in various types of surgical procedures in the human body. Optical energy provides several benefits over electrical or mechanical surgery, including the ability to selectively target specific tissue types while preserving others. Specialty fiber optic tips have also been introduced to further customize delivery of laser energy to the tissue. Recent evolution in lasers and miniaturization has opened up opportunities for many novel surgical techniques. Currently, ophthalmic surgeons use relatively invasive mechanical tools to dissect retinal deposits which occur in proliferative diabetic retinopathy. By using the tight focusing properties of microspheres combined with the short optical penetration depth of the Erbium:YAG laser and mid-IR fiber delivery, a precise laser scalpel can be constructed as an alternative, less invasive and more precise approach to this surgery. Chains of microspheres may allow for a self limiting ablation depth of approximately 10 microm based on the defocusing of paraxial rays. The microsphere laser scalpel may also be integrated with other surgical instruments to reduce the total number of handpieces for the surgeon. In current clinical laser lithotripsy procedures, poor input coupling of the Holmium:YAG laser energy frequently damages and requires discarding of the optical fiber. However, recent stone ablation studies with the Thulium fiber laser have provided comparable results to the Ho:YAG laser. The improved spatial beam profile of the Thulium fiber laser can also be efficiently coupled into a fiber approximately one third the diameter and reduces the risk of damaging the fiber input. For this reason, the trunk optical fiber minus the distal fiber tip can be preserved between procedures. The distal fiber tip, which degrades during stone ablation, could be made detachable and disposable. A novel, low-profile, twist-locking, detachable distal fiber tip interface was designed, assembled, and tested for use in Thulium fiber laser lithotripsy. A 1.00-mm-outer-diameter detachable fiber tip interface was designed, constructed, and tested ex vivo on urinary stones in the laboratory. Similar stone ablation rates between the previously studied tapered distal fiber tip and the detachable fiber tip were measured. For urologists desiring faster TFL lithotripsy procedures, the incorporation of detachable distal fiber tips allows for rapid replacement of damaged fiber tips without concern about the laser to trunk fiber connection. This method for preserving the trunk fiber could be a motivation for integrating a dedicated laser fiber into the ureteroscope, with detachable distal tips, thus freeing the working channel for the use of other surgical instruments. During laser lithotripsy, distal fiber tip degradation increases as the fiber core diameter decreases. However, smaller fiber diameters (≤ 200 microm) are more desirable because of increased saline irrigation rates in the single working channel of the ureteroscope and less impact on ureteroscope deflection. A hollow fiber cap is proposed to reduced fiber tip degradation in small diameter fibers, without compromising stone ablation rates. The disadvantage of the hollow fiber tip observed in the study is the increase in stone retropulsion. However, integrating the hollow fiber tip with a clinically used stone basket may allow for a robust stone ablation instrument that also minimizes retropulsion. These surgical approaches involving novel specialty fiber optic tip designs are discussed in this thesis.

Comparison between the Amount of Environmental Change and the Amount of Transcriptome Change

PubMed Central

Ogata, Norichika; Kozaki, Toshinori; Yokoyama, Takeshi; Hata, Tamako; Iwabuchi, Kikuo

2015-01-01

Cells must coordinate adjustments in genome expression to accommodate changes in their environment. We hypothesized that the amount of transcriptome change is proportional to the amount of environmental change. To capture the effects of environmental changes on the transcriptome, we compared transcriptome diversities (defined as the Shannon entropy of frequency distribution) of silkworm fat-body tissues cultured with several concentrations of phenobarbital. Although there was no proportional relationship, we did identify a drug concentration “tipping point” between 0.25 and 1.0 mM. Cells cultured in media containing lower drug concentrations than the tipping point showed uniformly high transcriptome diversities, while those cultured at higher drug concentrations than the tipping point showed uniformly low transcriptome diversities. The plasticity of transcriptome diversity was corroborated by cultivations of fat bodies in MGM-450 insect medium without phenobarbital and in 0.25 mM phenobarbital-supplemented MGM-450 insect medium after previous cultivation (cultivation for 80 hours in MGM-450 insect medium without phenobarbital, followed by cultivation for 10 hours in 1.0 mM phenobarbital-supplemented MGM-450 insect medium). Interestingly, the transcriptome diversities of cells cultured in media containing 0.25 mM phenobarbital after previous cultivation (cultivation for 80 hours in MGM-450 insect medium without phenobarbital, followed by cultivation for 10 hours in 1.0 mM phenobarbital-supplemented MGM-450 insect medium) were different from cells cultured in media containing 0.25 mM phenobarbital after previous cultivation (cultivation for 80 hours in MGM-450 insect medium without phenobarbital). This hysteretic phenomenon of transcriptome diversities indicates multi-stability of the genome expression system. Cellular memories were recorded in genome expression networks as in DNA/histone modifications. PMID:26657512

Alternative blade materials for technical and ecological optimization of a hydraulic pressure machine

NASA Astrophysics Data System (ADS)

Schwyzer, Olivier; Saenger, Nicole

2016-11-01

The Hydraulic Pressure Machine (HPM) is an energy converter to exploit head differences between 0.5 and 2.5 m in small streams and irrigation canals. Previous investigations show that efficiencies above 60% are possible. Several case studies indicate good continuity for aquatic life (e.g. fish) and bed load for the technology. The technology is described as an economically and ecologically viable option for small scale hydropower generation. Primary goal of this research is to improve the HPM blade design regarding its continuity properties by maintaining good efficiency rates. This is done by modifying the blade tip and testing within a large physical model under laboratory condition. Blade tips from steel (conventional - reference case) and a combination of EPDM rubber and steel as sandwich construction (rubber, steel, rubber - adhesive layered) are tested and compared. Both materials reach similar values for hydraulic efficiency (approx. 58%) and mechanical power output (approx. 220 W). The variation of different gap sizes pointed out the importance of small clearance gaps to reach high efficiencies. For assessing the two blade tip materials regarding continuity for aquatic life, fish dummies were led through the wheel. Analysis of slow motion video of dummies hit by the blade show significant advantages for the EPDM blade tip. The EPDM rubber allows to bend and thus reduces the shock and the probability for cuts on the fish dummy. It was shown that blade tips from EPDM have certain advantages regarding continuity compared to standard blade tips from steel. No compromise regarding energy production had to be made. These results from the HPM can be transferred to breast shot water wheel and may be applied for new and retrofitting projects.

Experiments on tip vortices interacting with downstream wings

NASA Astrophysics Data System (ADS)

Chen, C.; Wang, Z.; Gursul, I.

2018-05-01

The interaction of meandering tip vortices shed from a leading wing with a downstream wing was investigated experimentally in a water tunnel using flow visualization, particle image velocimetry measurements, and volumetric velocity measurements. Counter-rotating upstream vortices may exhibit sudden variations of the vortex core location when the wing-tip separation is within approximately twice the vortex core radius. This is caused by the formation of vortex dipoles near the wing tip. In contrast, co-rotating upstream vortices do not exhibit such sensitivity. Large spanwise displacement of the trajectory due to the image vortex is possible when the incident vortex is further inboard. For both co-rotating and counter-rotating vortices, as long as there is no direct impingement upon the wing, there is a little change in the structure of the time-averaged vortex past the wing, even though the tip vortex shed from the downstream wing may be substantially weakened or strengthened. In the absence of the downstream wing, as well as for weak interactions, the most energetic unsteady modes represent the first helical mode | m| = 1, which is estimated from the three-dimensional Proper Orthogonal Decomposition modes and has a very large wavelength, on the order of 102 times the vortex core radius, λ/ a = O(102). Instantaneous vorticity measurements as well as flow visualization suggest the existence of a smaller wavelength, λ/ a = 5-6, which is not among the most energetic modes. These two-orders of magnitude different wavelengths are in agreement with the previous measurements of tip vortices and also exhibit qualitative agreement with the transient energy growth analysis. The very long wavelength mode in the upstream vortex may persist during the interaction, and reveal coupling with the trailing vortex as well as increased meandering.

Scapular tip and latissimus dorsi osteomyogenous free flap for the reconstruction of a maxillectomy defect: A minimally invasive transaxillary approach.

PubMed

Park, Sung Joon; Jeong, Woo-Jin; Ahn, Soon-Hyun

2017-11-01

The purpose of this study was to propose a novel, minimally invasive transaxillary approach for harvesting the scapular tip and latissimus dorsi osteomyogenous free flap for the reconstruction of a maxillectomy defect. A retrospective case series study of 4 patients who underwent reconstruction using a scapular tip composite free flap through the transaxillary approach was conducted. The data (age, sex, pathology, previous treatment and adjuvant treatment) were collected and analysed. Total operation time, number of hospital days and the cosmetic and functional outcome of reconstruction were analysed. Two male and two female patients were enrolled in this study. The patients' ages ranged from 52 to 59 years. All the patients had maxillectomy defects, with at least a classification of Okay type II, which were successfully reconstructed using a scapular tip and latissimus dorsi free flap through a minimally invasive transaxillary approach. The entire operation time for the primary tumour surgery and reconstruction ranged from 6.2 to 12.1 h (mean, 11.1 h). The average length of the hospital stay was 13 days (range, 10-16 days). No major donor site morbidity was observed, and there was no graft failure that required revision or exploration surgery. The minimally invasive transaxillary approach for harvesting the scapular tip and latissimus dorsi osteomyogenous free flap for the reconstruction of maxillectomy defect is a promising approach for more favourable functional and aesthetic outcomes when compared to the use of other bone containing free flaps and the classic approach for harvesting scapular tip and latissimus dorsi free flap. Copyright © 2017 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

Tipping news in information accumulation system

NASA Astrophysics Data System (ADS)

Shin, J. K.

2010-05-01

As a continuous opinion dynamics model, the information accumulation system (IAS) includes three basic mechanisms of the news, the inheritance and the diffusion as contributing to the information accumulation process of a system. A system is composed of agents who diffuse information through internal interaction, while each of them has incomplete memory or inheritance rate. The news comes from external sources of information, such as mass media. Previously the model IAS was studied only for the small news problems. In this study, a tipping news problem is considered. A key question of the problem is: what is the minimum strength of advertisement that can tip the minority opinion to a majority one? Dynamics of the IAS is briefly revisited with a special interest on nonlinear behavior of the model. In particular, it is shown that a discrete map of the IAS for a single color problem can be transformed into a logistic map, from which the dynamics of the IAS can be better understood. To show the applicability of the IAS model, the result is applied to explain the concept of the critical population size, which claims that there is a minimum population size for a social knowledge system to be continuously inherited without being lost. And critical size of the tipping news is found analytically in terms of IAS parameters. Some of the key results from the present study are compared in detail with the results from the Brownian particle model, which is believed to be the most similar model to the IAS. The concept of tipping news is used to show that a traditional society can tip at an exceptionally low inter-community exposure. Finally, the result was applied to the language competition problem.

Nasal Sculpting: Calculated and Predictable Tip Elevation With Cephalic Trim

PubMed Central

Redstone, Jeremiah S.; Nguyen, Jonathan; North, Durham Alan; Hazani, Ron; Drury, Brad; Yoder, Eric M.; Cooperman, Ross D.; Yoder, Virginia; Little, Jarrod A.; Florman, Larry D.; Wilhelmi, Bradon J.

2015-01-01

Background: Rhinoplasty techniques to affect nasal tip rotation are well described. Cephalic alar trim is a powerful method for achieving tip elevation. Previous studies and texts provide aesthetic guidelines for nasolabial angles. Often, surgeon experience determines the degree of lower lateral cartilage resection to achieve optimal results. This study analyzes the change in tip elevation with measured resections of the lower lateral cartilages. This can aid the surgeon in accurately predicting the effect of cephalic alar trim on tip elevation. Methods: Ten fresh cadaveric dissections were performed to determine the change in nasolabial angles after cephalic trim of the lower lateral cartilage. Closed rhinoplasty technique was performed using marginal and intercartilaginous incisions to expose the lower lateral cartilage. Caliper measurements of the lower lateral cartilage were recorded. Serial cephalic trim was performed in 25% increments. True lateral photographs were obtained before and after each serial excision. Nasolabial angle measurements were obtained using a digital goniometer for digital photo analysis. Results: Four female and 6 male cadavers were evaluated. The mean initial nasolabial angle was 106° ± 2°. The mean lower lateral cartilage width was 9.45 ± 1.38 mm. Serial 25% reductions in lower lateral cartilage height resulted in a mean total nasolabial angle change of 7.4°, 12.9°, and 19.6°, respectively. The mean incremental change in the nasolabial angle was 6.47° ± 1.25°. Conclusion: The nasolabial angle is an essential aesthetic feature. Cephalic trim is a key maneuver in affecting the nasolabial angle. A 25% lower lateral cartilage cephalic trim correlates with an average change in the nasolabial angle of 6.47°. Knowledge of the cephalic trim to nasolabial angle relationship aids in achieving desired tip elevation. PMID:26171091

Treatment compliance in cystic fibrosis patients with chronic Pseudomonas aeruginosa infection treated with tobramycin inhalation powder: The FREE study.

PubMed

Blasi, Francesco; Carnovale, Vincenzo; Cimino, Giuseppe; Lucidi, Vincenzina; Salvatore, Donatello; Messore, Barbara; Bartezaghi, Marta; Muscianisi, Elisa; Porpiglia, Pasquale Alberto

2018-05-01

A high treatment burden with nebulised therapies in cystic fibrosis (CF) patients is the major limitation for treatment compliance; moreover, studies on treatment compliance with inhaled antibiotics are limited. This study assessed compliance to TOBI ® Podhaler™ (TIP) treatment in CF patients with chronic Pseudomonas aeruginosa (Pa) infections in a real-world setting using the Italian Treatment Adherence CF Questionnaire (ITA-CFq). This longitudinal, multicentre, cohort study included 2 follow-up (FU) visits: FU-1 at 3-months±15-days from the baseline visit and FU-2 at the end of third TIP cycle (or 6-months after enrolment, whichever occurred first). The effect of TIP on quality-of-life (QoL) and treatment satisfaction were evaluated using Cystic Fibrosis Questionnaire-Revised (CFQ-R) and Treatment Satisfaction Questionnaire for Medication (TSQM), respectively. Overall compliance to treatments was assessed using ITA-CFq. Eighty-two patients (mean age, 24.8 ± 7.9 years), including 22 paediatric patients (age, <18 years), were enrolled in the study; 56 (68.3%) patients, including 17 paediatric patients, completed the study. At baseline, the mean compliance score to aerosol antibiotic treatment was 7.8 ± 3.2; upon introducing TIP, the compliance score improved to 9.4 ± 1.2 at the FU-1 and thereafter remained stable at 9.5 ± 1.2. TSQM was higher for the convenience domain (74.2 ± 17.1 at enrolment and slightly improved to 77.8 ± 15.9 at FU-2) following TIP initiation. No substantial effect of TIP was observed on the QoL when measured using the revised CFQ-R. The safety profile was in line with previous findings. TIP was convenient to use and led to improved treatment adherence in CF patients with chronic Pa-infection. Copyright © 2018 Elsevier Ltd. All rights reserved.

Aerodynamic Analysis of Variable Geometry Raked Wingtips for Mid-Range Transonic Transport Aircraft

NASA Astrophysics Data System (ADS)

Jingeleski, David J.

Previous applications have shown that a wingtip treatment on a commercial airliner will reduce drag and increase fuel efficiency and the most common types of treatment are blended winglets and raked wingtips. With Boeing currently investigating novel designs for its next generation of airliners, a variable geometry raked wingtip novel control effector (VGRWT/NCE) was studied to determine the aerodynamic performance benefits over an untreated wingtip. The Boeing SUGAR design employing a truss-braced wing was selected as the baseline. Vortex lattice method (VLM) and computational fluid dynamics (CFD) software was implemented to analyze the aerodynamic performance of such a configuration applied to a next-generation, transonic, mid-range transport aircraft. Several models were created to simulate various sweep positions for the VGRWT/NCE tip, as well as a baseline model with an untreated wingtip. The majority of investigation was conducted using the VLM software, with CFD used largely as a validation of the VLM analysis. The VGRWT/NCE tip was shown to increase the lift of the wing while also decreasing the drag. As expected, the unswept VGRWT/NCE tip increases the amount of lift available over the untreated wingtip, which will be very beneficial for take-off and landing. Similarly, the swept VGRWT/NCE tip reduced the drag of the wing during cruise compared to the unmodified tip, which will favorably impact the fuel efficiency of the aircraft. Also, the swept VGRWT/NCE tip showed an increase in moment compared to the unmodified wingtip, implying an increase in stability, as well providing an avenue for roll control and gust alleviation for flexible wings. CFD analysis validated VLM as a useful low fidelity tool that yielded quite accurate results. The main results of this study are tabulated "deltas" in the forces and moments on the VGRWT/NCE tip as a function of sweep angle and aileron deflection compared to the baseline wing. A side study of the effects of the joint between the main wing and the movable tip showed that the drag impact can be kept small by careful design.

Beam spot diameter of the near-field scanning electron microscopy.

PubMed

Kyritsakis, A; Xanthakis, J P

2013-02-01

We have examined the beam spot diameter at the anode of the scanning electron microscopy (SEM) in the near-field mode as a function of the anode-tip distance d. The detector lateral resolution of this type of microscopy is approximately equal to this spot diameter. For our calculations we have simulated the apex region of the tip with an ellipsoid of revolution of radii R₁ and R₂ with R₁>R₂ as suggested by TEM images of the realistic tips. We have then solved the Laplace equation to obtain the electrostatic potential and to this we have added a spherical image potential. The calculated electrostatic field is highly asymmetric, being strong along the tip-axis and weakening quickly towards the sides. When a 3-dimensional WKB approximation is used to calculate the electron paths corresponding to such a potential, the latter are shown to bend significantly towards the vertical (tip-axis) direction producing a beam narrowing effect very similar to the beam narrowing effect we discovered for the traditional SEM case. When the values of R₁, R₂ are chosen from fittings to the TEM images of the tips used in the experiments, the beam spot diameter W at the anode (d=25 nm) varies from 12.5 nm to 9 nm depending on the fitted R₁, R₂. These values of W are considerably smaller than previously predicted by calculating solid angles of emission from spherical surfaces (41 nm) but also much closer to the detector lateral resolution (6-7 nm) obtained from differentiating the experimental current step. This trend continued at all other d examined. Furthermore the beam width W was found to decrease quickly with increasing sharpness S=R₁/R₂ of the tip and then saturate. W is also decreasing with decreasing R₁, R₂ with S kept constant. We deduce that the sharpness of the tip is important not only for creating high extraction fields but also for guaranteeing a very small beam spot diameter. Copyright © 2012 Elsevier B.V. All rights reserved.

Crack curving in a ductile pressurized fuselage

NASA Astrophysics Data System (ADS)

Lam, Paul W.

Moire interferometry was used to study crack tip displacement fields of a biaxially loaded cruciform type 0.8mm thick 2024-T3 aluminum specimen with various tearstrap reinforcement configurations: Unreinforced, Bonded, Bonded+Riveted, and Machined Pad-up. A program was developed using the commercially available code Matlab to derive strain, stress, and integral parameters from the experimental displacements. An FEM model of the crack tip area, with experimental displacements as boundary conditions, was used to validate FEM calculations of crack tip parameters. The results indicate that T*-integral parameter reaches a value of approximately 120 MPa-m0.5 during stable crack propagation which agrees with previously published values for straight cracks in the same material. The approximate computation method employed in this study uses a partial contour around the crack tip that neglects the contribution from the portion behind the crack tip where there is significant unloading. Strain distributions around the crack tip were obtained from experimental displacements and indicate that Maximum Principal Strain or Equivalent Strain can predict the direction of crack propagation, and is generally comparable with predictions using the Erdogan-Sih and Kosai-Ramulu-Kobayashi criteria. The biaxial tests to failure showed that the Machined Pad-up specimen carried the highest load, with the Bonded specimen next, at 78% of the Machined Pad-up value. The Bonded+Riveted specimen carried a lower load than the Bonded, at 67% of the Machined Pad-up value, which was the same as that carried by the Unreinforced specimen. The tearstraps of the bonded specimens remained intact after the specimen failed while the integrally machined reinforcement broke with the specimen. FEM studies were also made of skin flapping in typical Narrow and Wide-body fuselage sections, both containing the same crack path from a full-scale fatigue test of a Narrow-body fuselage. Results indicate that the magnitude of CTOA and CTOD depends on the structural geometry, and including plasticity increases the crack tip displacements. An estimate of the strain in the skin flaps at the crack tip may indicate the tendency for flapping. Out-of-plane effects become significant as the crack propagates and curves.

Controls Considerations for Turbine Active Clearance Control

NASA Technical Reports Server (NTRS)

Melcher, Kevin J.

2004-01-01

This presentation discusses active control of turbine tip clearance from a control systems perspective. It is a subset of charts that were presented at the 2003 meeting of the International Society of Air Breathing Engines which was held August 31 through September 5 in Cleveland, Ohio. The associated reference paper is cited at the end of the presentation. The presentation describes active tip clearance control research being conducted by NASA to improve turbine engine systems. The target application for this effort is commercial aircraft engines. However, it is believed that the technologies developed as part of this research will benefit a broad spectrum of current and future turbomachinery. The first part of the presentation discusses the concept of tip clearance, problems associated with it, and the benefits of controlling it. It lays out a framework for implementing tip clearance controls that enables the implementation to progress from purely analytical to hardware-in-the-loop to fully experimental. And it briefly discusses how the technologies developed will be married to the previously described ACC Test Rig for hardware-in-the-loop demonstrations. The final portion of the presentation, describes one of the key technologies in some detail by presenting equations and results for a functional dynamic model of the tip clearance phenomena. As shown, the model exhibits many of the clearance dynamics found in commercial gas turbine engines. However, initial attempts to validate the model identified limitations that are being addressed to make the model more realistic.

Fabrication and characterization of chitosan nanoparticles and collagen-loaded polyurethane nanocomposite membrane coated with heparin for atrial septal defect (ASD) closure.

PubMed

Kaiser, Eva; Jaganathan, Saravana Kumar; Supriyanto, Eko; Ayyar, Manikandan

2017-07-01

Atrial septal defect (ASD) constitutes 30-40% of all congenital heart diseases in adults. The most common complications in the treatment of ASD are embolization of the device and thrombosis formation. In this research, an occluding patch was developed for ASD treatment using a well-known textile technology called electrospinning. For the first time, a cardiovascular occluding patch was fabricated using medical grade polyurethane (PU) loaded with bioactive agents namely chitosan nanoparticles (Cn) and collagen (Co) which is then coated with heparin (Hp). Fourier transform infrared spectrum showed characteristic vibrations of several active constituents and changes in the absorbance due to the inclusion of active ingredients in the patch. The contact angle analysis demonstrated no significant decrease in contact angle compared to the control and the composite patches. The structure of the electrospun nanocomposite (PUCnCoHp) was examined through scanning electron microscopy. A decrease in nanofiber diameter between control PU and PUCnCoHp nanocomposite was observed. Water uptake was found to be decreased for the PUCnCoHp nanocomposite against the control. The hemocompatibility properties of the PUCnCoHp ASD occluding patch was inferred through in vitro hemocompatibility tests like activated partial thromboplastin time (APTT), prothrombin time (PT) and hemolysis assay. It was found that the PT and APTT time was significantly prolonged for the fabricated PUCnCoHp ASD occluding patch compared to the control. Likewise, the hemolysis percentage was also decreased for the PUCnCoHp ASD patch against the control. In conclusion, the developed PUCnCoHp patch demonstrates potential properties to be used for ASD occlusion.

Outcomes of Interventions Via a Transradial Approach for Dysfunctional Brescia-Cimino Fistulas

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

Chen Shyhming; Hang Chiling; Yip Honkan

2009-09-15

The transradial artery approach to angioplasty has rarely been reported as a method for treating dysfunctional Brescia-Cimino fistulas. This study evaluated the feasibility, safety, and 1-year efficacy of this method for treating dysfunctional Brescia-Cimino fistulas. We retrospectively evaluated 154 consecutive procedures in 131 patients (age, 58.3 {+-} 11.6 years; male, 48.1%) who underwent the transradial approach in dysfunctional Brescia-Cimino fistulas in the 1-year period after the procedure. The operator determined the use of a regular or a cutting balloon (two cases) in combination with urokinase injection (one case) or catheter thromboaspiration. Radial artery puncture was successful in all cases. Fifty-twomore » cases (33.8%) had totally occluded fibrotic lesions. The overall anatomic success rate and clinical success rate were 61% (94/154) and 81.1% (125/154), respectively. In cases with a totally occluded fibrotic lesion, the clinical success rate was 46%. Successful intervention was associated with a significant reduction in the radial arterial systolic and diastolic pressures. There were no complications of symptomatic arterial embolization or pulmonary embolism, and one complication of venous rupture was successfully treated by compression. The primary patency rates based on intention-to-treat were 75.3% at 30 days and 39.0% at 1 year after the procedure. Excluding the cases with a totally occluded lesion, the clinical success rate was 99% (101/102) and the primary patency rates were 84.3% (86/102) and 52.0% (53/102) at 3 months and 1 year after the procedure, respectively. In conclusion, the transradial approach is a feasible, safe, and effective alternative for catheter intervention for dysfunctional Brescia-Cimino fistulas. Its success rate in cases with a totally occluded fibrotic lesion is unsatisfactory.« less

The Functional Lumen Imaging Probe Detects Esophageal Contractility not Observed with Manometry in Patients with Achalasia

PubMed Central

Carlson, Dustin A.; Lin, Zhiyue; Kahrilas, Peter J.; Sternbach, Joel; Donnan, Erica N.; Friesen, Laurel; Listernick, Zoe; Mogni, Benjamin; Pandolfino, John E.

2015-01-01

Background & Aims The functional lumen imaging probe (FLIP) could improve characterization of achalasia subtypes by detecting non-occlusive esophageal contractions not observed with standard manometry. We aimed to evaluate for esophageal contractions during volumetric distention in patients with achalasia using FLIP topography. Methods Fifty one treatment-naïve patients with achalasia, defined and sub-classified by high-resolution esophageal pressure topography, and 10 asymptomatic individuals (controls) were evaluated with the FLIP during endoscopy. During stepwise distension, simultaneous intra-bag pressures and 16 channels of cross-sectional areas were measured; data were exported to software that generated FLIP topography plots. Esophageal contractility was identified by noting periods of reduced luminal diameter. Esophageal contractions were further characterized by propagation direction, repetitiveness, and based on whether they were occluding or non-occluding. Results Esophageal contractility was detected in all 10 controls: 8/10 had repetitive, antegrade, contractions and 9/10 had occluding contractions. Contractility was detected in 27% (4/15) of patients with type I achalasia and 65% (18/26, including 9 with occluding contractions) of patients with type II achalasia. Contractility was detected in all 10 patients with type III achalasia; 8 of these patients had a pattern of contractility not observed in controls (repetitive, retrograde contractions). Conclusions Esophageal contractility not observed with manometry can be detected in patients with achalasia using FLIP topography. The presence and patterns of contractility detected with FLIP topography may represent variations in pathophysiology, such as mechanisms of pan-esophageal pressurization in patients with type II achalasia. These findings could have implications for additional sub-classification to supplement prediction of the achalasia disease course. PMID:26278501

Direct Percutaneous Left Ventricular Access and Port Closure

PubMed Central

Barbash, Israel M.; Saikus, Christina E.; Faranesh, Anthony Z.; Ratnayaka, Kanishka; Kocaturk, Ozgur; Chen, Marcus Y.; Bell, Jamie A.; Virmani, Renu; Schenke, William H.; Hansen, Michael S.; Slack, Michael C.; Lederman, Robert J.

2012-01-01

Objectives This study sought to evaluate feasibility of nonsurgical transthoracic catheter-based left ventricular (LV) access and closure. Background Implanting large devices, such as mitral or aortic valve prostheses, into the heart requires surgical exposure and repair. Reliable percutaneous direct transthoracic LV access and closure would allow new nonsurgical therapeutic procedures. Methods Percutaneous direct LV access was performed in 19 swine using real-time magnetic resonance imaging (MRI) and an “active” MRI needle antenna to deliver an 18-F introducer sheath. The LV access ports were closed percutaneously using a commercial ventricular septal defect occluder and an “active” MRI delivery cable for enhanced visibility. We used “permissive pericardial tamponade” (temporary fluid instillation to separate the 2 pericardial layers) to avoid pericardial entrapment by the epicardial disk. Techniques were developed in 8 animals, and 11 more were followed up to 3 months by MRI and histopathology. Results Imaging guidance allowed 18-F sheath access and closure with appropriate positioning of the occluder inside the transmyocardial tunnel. Of the survival cohort, immediate hemostasis was achieved in 8 of 11 patients. Failure modes included pericardial entrapment by the epicardial occluder disk (n = 2) and a true-apex entry site that prevented hemostatic apposition of the endocardial disk (n = 1). Reactive pericardial effusion (192 ± 118 ml) accumulated 5 ± 1 days after the procedure, requiring 1-time drainage. At 3 months, LV function was preserved, and the device was endothelialized. Conclusions Direct percutaneous LV access and closure is feasible using real-time MRI. A commercial occluder achieved hemostasis without evident deleterious effects on the LV. Having established the concept, further clinical development of this approach appears realistic. PMID:22192372

Limb suction evoked during arterial occlusion causes systemic sympathetic activity in humans

PubMed Central

Cui, Jian; Blaha, Cheryl; Herr, Michael D.; Drew, Rachel C.; Muller, Matthew D.

2015-01-01

Venous saline infusions in an arterially occluded forearm evokes reflex increases in muscle sympathetic nerve activity (MSNA) and blood pressure (BP). We hypothesized that the application of suction to the human limbs would activate this venous distension reflex and raise sympathetic outflow. We placed airtight pressure tanks and applied 100 mmHg negative pressure to an arterially occluded limb (occlusion and suction, O&S) to induce tissue deformation without fluid translocation. BP, heart rate (HR), and MSNA were assessed in 19 healthy subjects during 2 min of arm or leg O&S. Occlusion without suction served as a control. During a separate visit, saline (5% forearm volume) was infused into veins of the arterially occluded arm (n = 13). The O&S increased limb circumference, MSNA burst rate (arm: Δ6.7 ± 0.7; leg: Δ6.8 ± 0.7 bursts/min), and total activity (arm: Δ199 ± 14; leg: Δ172 ± 22 units/min) and BP (arm: Δ4.3 ± 0.3; leg: Δ9.4 ± 1.4 mmHg) from the baseline. The MSNA and BP responses during arm O&S correlated with those during leg O&S. Occlusion alone had no effect on MSNA and BP. MSNA (r = 0.607) responses during arm O&S correlated with those evoked by the saline infusion into the arm. These correlations suggest that sympathetic activation during limb O&S is likely, at least partially, to be evoked via the venous distension reflex. These data suggest that suction of an occluded limb evokes sympathetic activation and that the limb venous distension reflex exists in arms and legs of normal humans. PMID:26136530

A Meta-analysis of Randomized Trials Comparing Surgery versus Endovascular Therapy for Thrombosed Arteriovenous Fistulas and Grafts in Hemodialysis

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

Kuhan, G., E-mail: gkuhan@nhs.net; Antoniou, G. A.; Nikam, M.

Purpose. To carry out a systematic review of randomized trials comparing surgery vs. endovascular therapy for occluded fistulas and grafts. Methods. All randomized trials which compared surgery and endovascular therapy for occluded fistulas and grafts were retrieved from 1990 onwards. The following search terms were used: 'haemodialysis,' 'thrombosis,' 'arteriovenous fistula,' 'arteriovenous shunt,' 'end stage renal failure' on Medline and PubMed. The results of the pooled data were analysed by a fixed-effect model. Results. There were no randomized trials comparing surgery vs. endovascular therapy for native fistulas and vein grafts. Six randomized studies reporting on 573 occluded grafts were identified. Technicalmore » success, need for access line and primary patency at 30 days were similar between the two groups (odds ratio [OR] 1.40, 95 % confidence interval [CI] 0.91-2.14; OR 0.77, 95 % CI 0.44-1.34; and OR 1.15, 95 % CI 0.79-1.68, respectively). There was no significant difference in morbidity at 30 days between groups (OR 1.12, 95 % CI 0.67-1.86). There were no statistical difference between the two groups for 1 year primary patency (OR 2.08, 95 % CI 0.97-4.45). Primary assisted patency at 1 year was better with surgery (OR 3.03, 95 % CI 1.12-8.18) in a single study. Conclusion. Comparable results to surgery have been achieved with endovascular techniques for occluded prosthetic grafts for dialysis access. Long-term data comparing the two groups were lacking. Further trials designed to encompass variation in methods are warranted in order to obtain the best available evidence particularly for native fistulas.« less

Long-Term Results of Transcatheter Closure of Patent Ductus Arteriosus in Infants Using Amplatzer Duct Occluder

PubMed Central

Behjati-Ardakani, Mostafa; Behjati-Ardakani, Mohammad-Amin; Hosseini, Seyed-Habibolla; Noori, Noormohammad

2013-01-01

Objective Patent ductus arteriosus (PDA) is one of the most frequently seen congenital heart diseases. Its closure is recommended because of the risk of infective endocardis, as well as morbidity and mortality in the long. The aim of this study was to assess the long term results of the transcatheter closure of PDA in infants using amplatzer duct occlude (ADO). Methods From May 2004 to September 2011, forty eight infants underwent transcatheter closure of PDA. A lateral or right anterior oblique view aortogram was done to locate PDA and to measure its size. Before discharge, repeat aortogram was performed to evaluate eventual residual shunt and to confirm the appropriate deployment of the ADO. Follow up evaluations were done with transthoracic echocardiography at discharge, 1 month, 6 months, 12 months and yearly thereafter. Findings The mean age of patients at procedure was 9.18±2.32 (range 3 to 12) months, mean weight 6.73±1.16 (range 4.5 to 10.1) kg. The PDA occluded completely in 20 out of the 48 patients. Twenty four patients had trivial or mild shunt and two patients had moderate residual shunt which disappeared in one patient within 24 hours and other patient with moderate shunt in 1 month. One patient (age 8 months) had mild LPA stenosis. The device emobolization occurred in two patients, immediately after the procedure in one and during night in the other patient Conclusion The long term results suggested that transcatheter closure of PDA using Amplatzer duct occluder is a safe and effective treatment in infants less than 1 year of age with minimal complications. PMID:24427494

Long-term outcome of 154 patients receiving balloon-occluded retrograde transvenous obliteration for gastric fundal varices.

PubMed

Imai, Yukinori; Nakazawa, Manabu; Ando, Satsuki; Sugawara, Kayoko; Mochida, Satoshi

2016-11-01

This study aims to clarify the long-term outcome of therapeutic strategies including balloon-occluded retrograde transvenous obliteration (B-RTO) for patients with gastric fundal varices. The subjects were 154 patients with gastric fundal varices fulfilling the criteria for receiving B-RTO. In patients showing variceal bleeding, endoscopic therapies and/or balloon tamponade was performed to achieve hemostasis. B-RTO was accomplished with injection of 5% ethanolamine oleate through a standard balloon catheter except for patients with atypical varices, in whom a microballoon catheter was used to occlude drainage vessels other than a gastrorenal shunt. In patients complicated with esophageal varices at baseline, endoscopic therapies were performed following B-RTO. Balloon-occluded retrograde transvenous obliteration was performed successfully in 147 patients (95%), including 15 patients using a microballoon catheter. Complete variceal obliteration was achieved in all patients. Additional endoscopic therapies for esophageal varices were performed in 31 patients. Gastric varices did not recur in any of these patients. The cumulative survival rates at 1, 3, and 5 years after B-RTO were 91%, 76%, and 72%, respectively. Child-Pugh scores and hepatocellular carcinoma complication were identified as prognostic factors associated with survival rates. The cumulative exacerbation rates of esophageal varices at 1, 3, and 5 years were 13%, 20%, and 27%, respectively, and rupture developed in six patients, which were successfully treated with endoscopic therapies. Therapeutic strategies including B-RTO with a microballoon catheter were useful to achieve a favorable outcome in patients with gastric fundal varices especially in those manifesting Child-Pugh class-A liver damage and/or those without hepatocellular carcinoma complication. © 2016 Journal of Gastroenterology and Hepatology Foundation and John Wiley & Sons Australia, Ltd.

Voice Quality After a Semi-Occluded Vocal Tract Exercise With a Ventilation Mask in Contemporary Commercial Singers: Acoustic Analysis and Self-Assessments.

PubMed

Fantini, Marco; Succo, Giovanni; Crosetti, Erika; Borragán Torre, Alfonso; Demo, Roberto; Fussi, Franco

2017-05-01

The current study aimed at investigating the immediate effects of a semi-occluded vocal tract exercise with a ventilation mask in a group of contemporary commercial singers. A randomized controlled study was carried out. Thirty professional or semi-professional singers with no voice complaints were randomly divided into two groups on recruitment: an experimental group and a control group. The same warm-up exercise was performed by the experimental group with an occluded ventilation mask placed over the nose and the mouth and by the control group without the ventilation mask. Voice was recorded before and after the exercise. Acoustic and self-assessment analysis were accomplished. The acoustic parameters of the voice samples recorded before and after training were compared, as well as the parameters' variations between the experimental and the control group. Self-assessment results of the experimental and the control group were compared too. Significant changes after the warm-up exercise included jitter, shimmer, and singing power ratio (SPR) in the experimental group. No significant changes were recorded in the control group. Significant differences between the experimental and the control group were found for ΔShimmer and ΔSPR. Self-assessment analysis confirmed a significantly higher phonatory comfort and voice quality perception for the experimental group. The results of the present study support the immediate advantageous effects on singing voice of a semi-occluded vocal tract exercise with a ventilation mask in terms of acoustic quality, phonatory comfort, and voice quality perception in contemporary commercial singers. Long-term effects still remain to be studied. Copyright © 2017 The Voice Foundation. Published by Elsevier Inc. All rights reserved.

Eye Tracking of Occluded Self-Moved Targets: Role of Haptic Feedback and Hand-Target Dynamics.

PubMed

Danion, Frederic; Mathew, James; Flanagan, J Randall

2017-01-01

Previous studies on smooth pursuit eye movements have shown that humans can continue to track the position of their hand, or a target controlled by the hand, after it is occluded, thereby demonstrating that arm motor commands contribute to the prediction of target motion driving pursuit eye movements. Here, we investigated this predictive mechanism by manipulating both the complexity of the hand-target mapping and the provision of haptic feedback. Two hand-target mappings were used, either a rigid (simple) one in which hand and target motion matched perfectly or a nonrigid (complex) one in which the target behaved as a mass attached to the hand by means of a spring. Target animation was obtained by asking participants to oscillate a lightweight robotic device that provided (or not) haptic feedback consistent with the target dynamics. Results showed that as long as 7 s after target occlusion, smooth pursuit continued to be the main contributor to total eye displacement (∼60%). However, the accuracy of eye-tracking varied substantially across experimental conditions. In general, eye-tracking was less accurate under the nonrigid mapping, as reflected by higher positional and velocity errors. Interestingly, haptic feedback helped to reduce the detrimental effects of target occlusion when participants used the nonrigid mapping, but not when they used the rigid one. Overall, we conclude that the ability to maintain smooth pursuit in the absence of visual information can extend to complex hand-target mappings, but the provision of haptic feedback is critical for the maintenance of accurate eye-tracking performance.

Eye Tracking of Occluded Self-Moved Targets: Role of Haptic Feedback and Hand-Target Dynamics

PubMed Central

Mathew, James

2017-01-01

Abstract Previous studies on smooth pursuit eye movements have shown that humans can continue to track the position of their hand, or a target controlled by the hand, after it is occluded, thereby demonstrating that arm motor commands contribute to the prediction of target motion driving pursuit eye movements. Here, we investigated this predictive mechanism by manipulating both the complexity of the hand-target mapping and the provision of haptic feedback. Two hand-target mappings were used, either a rigid (simple) one in which hand and target motion matched perfectly or a nonrigid (complex) one in which the target behaved as a mass attached to the hand by means of a spring. Target animation was obtained by asking participants to oscillate a lightweight robotic device that provided (or not) haptic feedback consistent with the target dynamics. Results showed that as long as 7 s after target occlusion, smooth pursuit continued to be the main contributor to total eye displacement (∼60%). However, the accuracy of eye-tracking varied substantially across experimental conditions. In general, eye-tracking was less accurate under the nonrigid mapping, as reflected by higher positional and velocity errors. Interestingly, haptic feedback helped to reduce the detrimental effects of target occlusion when participants used the nonrigid mapping, but not when they used the rigid one. Overall, we conclude that the ability to maintain smooth pursuit in the absence of visual information can extend to complex hand-target mappings, but the provision of haptic feedback is critical for the maintenance of accurate eye-tracking performance. PMID:28680964

Intracranial aneurysms: optimized diagnostic tools call for thorough interdisciplinary treatment strategies.

PubMed

Mueller, Oliver M; Schlamann, Marc; Mueller, Daniela; Sandalcioglu, I Erol; Forsting, Michael; Sure, Ulrich

2011-09-01

Intracranial aneurysms (IAs) require deliberately selected treatment strategies as they are incrementally found prior to rupture and deleterious subarachnoid haemorrhage (SAH). Multiple and recurrent aneurysms necessitate both neurointerventionalists and neurosurgeons to optimize aneurysmal occlusion in an interdisciplinary effort. The present study was conducted to condense essential strategies from a single neurovascular centre with regard to the lessons learned. Medical charts of 321 consecutive patients treated for IAs at our centre from September 2008 until December 2010 were retrospectively analysed for clinical presentation of the aneurysms, multiplicity and treatment pathways. In addition, a selective Medline search was performed. A total of 321 patients with 492 aneurysms underwent occlusion of their symptomatic aneurysm: 132 (41.1%) individuals were treated surgically, 189 (58.2%) interventionally; 138 patients presented with a SAH, of these 44.2% were clipped and 55.8% were coiled. Aneurysms of the middle cerebral artery were primarily occluded surgically (88), whereas most of the aneurysms of the internal carotid artery and anterior communicating artery (114) were treated endovascularly. Multiple aneurysms (range 2-5 aneurysms/individual) were diagnosed in 98 patients (30.2%). During the study period 12 patients with recurrent aneurysms were allocated to another treatment modality (previously clip to coil and vice versa). Our data show that successful interdisciplinary occlusion of IAs is based on both neurosurgical and neurointerventional therapy. In particular, multiple and recurrent aneurysms require tailored individual approaches to aneurysmal occlusion. This is achieved by a consequent interdisciplinary pondering of the optimal strategy to occlude IAs in order to prevent SAH.

Structure determination of a major facilitator peptide transporter: Inward facing PepTSt from Streptococcus thermophilus crystallized in space group P3121

PubMed Central

Quistgaard, Esben M.; Martinez Molledo, Maria

2017-01-01

Major facilitator superfamily (MFS) peptide transporters (typically referred to as PepT, POT or PTR transporters) mediate the uptake of di- and tripeptides, and so play an important dietary role in many organisms. In recent years, a better understanding of the molecular basis for this process has emerged, which is in large part due to a steep increase in structural information. Yet, the conformational transitions underlying the transport mechanism are still not fully understood, and additional data is therefore needed. Here we report in detail the detergent screening, crystallization, experimental MIRAS phasing, and refinement of the peptide transporter PepTSt from Streptococcus thermophilus. The space group is P3121, and the protein is crystallized in a monomeric inward facing form. The binding site is likely to be somewhat occluded, as the lobe encompassing transmembrane helices 10 and 11 is markedly bent towards the central pore of the protein, but the extent of this potential occlusion could not be determined due to disorder at the apex of the lobe. Based on structural comparisons with the seven previously determined P212121 and C2221 structures of inward facing PepTSt, the structural flexibility as well as the conformational changes mediating transition between the inward open and inward facing occluded states are discussed. In conclusion, this report improves our understanding of the structure and conformational cycle of PepTSt, and can furthermore serve as a case study, which may aid in supporting future structure determinations of additional MFS transporters or other integral membrane proteins. PMID:28264013

The role of vision on hand preshaping during reach to grasp.

PubMed

Winges, Sara A; Weber, Douglas J; Santello, Marco

2003-10-01

During reaching to grasp objects with different shapes hand posture is molded gradually to the object's contours. The present study examined the extent to which the temporal evolution of hand posture depends on continuous visual feedback. We asked subjects to reach and grasp objects with different shapes under five vision conditions (VCs). Subjects wore liquid crystal spectacles that occluded vision at four different latencies from onset of the reach. As a control, full-vision trials (VC5) were interspersed among the blocked vision trials. Object shapes and all VCs were presented to the subjects in random order. Hand posture was measured by 15 sensors embedded in a glove. Linear regression analysis, discriminant analysis, and information theory were used to assess the effect of removing vision on the temporal evolution of hand shape. We found that reach duration increased when vision was occluded early in the reach. This was caused primarily by a slower approach of the hand toward the object near the end of the reach. However, vision condition did not have a significant effect on the covariation patterns of joint rotations, indicating that the gradual evolution of hand posture occurs in a similar fashion regardless of vision. Discriminant analysis further supported this interpretation, as the extent to which hand posture resembled object shape and the rate at which hand posture discrimination occurred throughout the movement were similar across vision conditions. These results extend previous observations on memory-guided reaches by showing that continuous visual feedback of the hand and/or object is not necessary to allow the hand to gradually conform to object contours.

Holistic processing for bodies and body parts: New evidence from stereoscopic depth manipulations.

PubMed

Harris, Alison; Vyas, Daivik B; Reed, Catherine L

2016-10-01

Although holistic processing has been documented extensively for upright faces, it is unclear whether it occurs for other visual categories with more extensive substructure, such as body postures. Like faces, body postures have high social relevance, but they differ in having fine-grain organization not only of basic parts (e.g., arm) but also subparts (e.g., elbow, wrist, hand). To compare holistic processing for whole bodies and body parts, we employed a novel stereoscopic depth manipulation that creates either the percept of a whole body occluded by a set of bars, or of segments of a body floating in front of a background. Despite sharing low-level visual properties, only the stimulus perceived as being behind bars should be holistically "filled in" via amodal completion. In two experiments, we tested for better identification of individual body parts within the context of a body versus in isolation. Consistent with previous findings, recognition of body parts was better in the context of a whole body when the body was amodally completed behind occluders. However, when the same bodies were perceived as floating in strips, performance was significantly worse, and not significantly different, from that for amodally completed parts, supporting holistic processing of body postures. Intriguingly, performance was worst for parts in the frontal depth condition, suggesting that these effects may extend from gross body organization to a more local level. These results provide suggestive evidence that holistic representations may not be "all-or-none," but rather also operate on body regions of more limited spatial extent.

Noninvasive laser coagulation of the canine vas deferens, in vivo

NASA Astrophysics Data System (ADS)

Cilip, Christopher M.; Ross, Ashley E.; Jarow, Jonathan P.; Fried, Nathaniel M.

2010-02-01

Development of a noninvasive vasectomy technique may eliminate male fear of complications (incision, bleeding, infection, and scrotal pain) and result in a more popular procedure. This study builds upon previously reported ex vivo tissue studies by exploring acute and short-term chronic in vivo canine studies. Isolation of the canine vas was achieved using a conventional vas ring clamp method. No perforation of the scrotal skin was necessary to occlude the vas. Laser radiation with a wavelength of 1075 nm, average power of 11.2 W, 500-ms pulse duration, 0.5 Hz pulse rate, and 3-mm-diameter spot was synchronized with cryogen spray cooling of the scrotal skin surface in a total of 8 dogs (n = 16 vasa) for a treatment time of 60 s. Burst pressure measurements were conducted at Days 0 and 21 (n = 8 vasa each day) to quantify the strength of vas closure. The vas was successfully thermally occluded in 15/16 (94%) procedures with 14/15 (93%) vas recording burst pressures above ejaculation pressure. One vas was not present, and another vas recorded a bursting pressure below ejaculation pressure. The coagulated vas bursting pressure averaged 283 +/- 34 mm Hg at Day 0 and 260 +/- 77 mm Hg at Day 21, significantly higher than reported vas ejaculation pressures of 136 +/- 29 mm Hg. Minor scrotal skin burns were observed during the recovery period. Noninvasive thermal occlusion of the vas is feasible in an in vivo canine model. Elimination of minor skin burns and longer term chronic in vivo canine studies are needed to confirm azospermia after vas occlusion without recanalization.

Central venous pressure and mean circulatory filling pressure in the dogfish Squalus acanthias: adrenergic control and role of the pericardium.

PubMed

Sandblom, Erik; Axelsson, Michael; Farrell, Anthony P

2006-11-01

Subambient central venous pressure (Pven) and modulation of venous return through cardiac suction (vis a fronte) characterizes the venous circulation in sharks. Venous capacitance was estimated in the dogfish Squalus acanthias by measuring the mean circulatory filling pressure (MCFP) during transient occlusion of cardiac outflow. We tested the hypothesis that venous return and cardiac preload can be altered additionally through adrenergic changes of venous capacitance. The experiments involved the surgical opening of the pericardium to place a perivascular occluder around the conus arteriosus. Another control group was identically instrumented, but lacked the occluder, and was subjected to the same pharmacological protocol to evaluate how pericardioectomy affected cardiovascular status. Routine Pven was negative (-0.08+/-0.02 kPa) in control fish but positive (0.09+/-0.01 kPa) in the pericardioectomized group. Injections of 5 microg/kg body mass (Mb) of epinephrine and phenylephrine (100 microg/kg Mb) increased Pven and MCFP, whereas isoproterenol (1 microg/kg Mb) decreased both variables. Thus, constriction and relaxation of the venous vasculature were mediated through the respective stimulation of alpha- and beta-adrenergic receptors. Alpha-adrenergic blockade with prazosin (1 mg/kg Mb) attenuated the responses to phenylephrine and decreased resting Pven in pericardioectomized animals. Our results provide convincing evidence for adrenergic control of the venous vasculature in elasmobranchs, although the pericardium is clearly an important component in the modulation of venous function. Thus active changes in venous capacitance have previously been underestimated as an important means of modulating venous return and cardiac performance in this group.

Incomplete aneurysm coverage after patent foramen ovale closure in patients with huge atrial septal aneurysm: effects on left atrial functional remodeling.

PubMed

Rigatelli, Gianluca; Ronco, Federico; Cardaioli, Paolo; Dell'avvocata, Fabio; Braggion, Gabriele; Giordan, Massimo; Aggio, Silvio

2010-08-01

Large devices are often implanted to treat patent foramen ovale (PFO) and atrial septal aneurysm (ASA) with increase risk of erosion and thrombosis. Our study is aimed to assess the impact on left atrium functional remodeling and clinical outcomes of partial coverage of the approach using moderately small Amplatzer ASD Cribriform Occluder in patients with large PFO and ASA. We prospectively enrolled 30 consecutive patients with previous stroke (mean age 36 +/- 9.5 years, 19 females), significant PFO, and large ASA referred to our center for catheter-based PFO closure. Left atrium (LA) passive and active emptying, LA conduit function, and LA ejection fraction were computed before and after 6 months from the procedure by echocardiography. The preclosure values were compared to values of a normal healthy population of sex and heart rate matched 30 patients. Preclosure values demonstrated significantly greater reservoir function as well as passive and active emptying, with significantly reduced conduit function and LA ejection fraction, when compared normal healthy subjects. All patients underwent successful transcatheter closure (25 mm device in 15 patients, 30 mm device in 6 patients, mean ratio device/diameter of the interatrial septum = 0.74). Incomplete ASA coverage in both orthogonal views was observed in 21 patients. Compared to patients with complete coverage, there were no differences in LA functional parameters and occlusion rates. This study confirmed that large ASAs are associated with LA dysfunction. The use of relatively small Amplatzer ASD Cribriform Occluder devices is probably effective enough to promote functional remodeling of the left atrium.

Optimal compliance for amblyopia therapy: occlusion with a translucent tape on the lens.

PubMed

Beneish, Raquel G; Polomeno, Robert C; Flanders, Michael E; Koenekoop, Robert K

2009-10-01

To demonstrate that optimal compliance to amblyopia therapy and a better visual outcome can be achieved by occluding the lens over the preferred eye with a translucent tape. Prospective study of amblyopic children. Eighty-four amblyopic children recruited from 2000 to 2006 at the Montreal Children's Vision Centre. A group of bilateral ametropes (mean age 3.8 years) were treated with glasses and occlusion of the sound eye with a translucent tape on the lens over the preferred eye, or an adhesive patch. The translucent tape reduced vision to hand motion at 0.3 m in the sound eye. Patients were divided into 2 groups depending on the treatment received. Group 1 (n = 36) was occluded with a translucent tape, and group 2 (n = 48) with a conventional adhesive patch, later replaced by the translucent tape. Twenty-five previously reported patients, treated with the conventional adhesive patch only, were used as controls (group 3). The mean amblyopic visual acuity was 20/100-2. Compliance was good in 36 patients (group 1), and was poor or deteriorated in 24/48 patients (group 2). Substituting the adhesive patch with a translucent tape permitted uninterrupted and prolonged occlusion, with a successful visual outcome. The amblyopic eye achieved a significantly better final vision (20/30+2; groups 1+2) than the controls (20/40+1; group 3) (p = 0.04). Sixty-four (76.19%) patients achieved >or=20/30. The translucent tape optimizes compliance and yields better vision by lengthening the duration of occlusion therapy and reducing the number of treatment failures due to noncompliance.

Elasto-capillarity in insect fibrillar adhesion.

PubMed

Gernay, Sophie; Federle, Walter; Lambert, Pierre; Gilet, Tristan

2016-08-01

The manipulation of microscopic objects is challenging because of high adhesion forces, which render macroscopic gripping strategies unsuitable. Adhesive footpads of climbing insects could reveal principles relevant for micro-grippers, as they are able to attach and detach rapidly during locomotion. However, the underlying mechanisms are still not fully understood. In this work, we characterize the geometry and contact formation of the adhesive setae of dock beetles (Gastrophysa viridula) by interference reflection microscopy. We compare our experimental results to the model of an elastic beam loaded with capillary forces. Fitting the model to experimental data yielded not only estimates for seta adhesion and compliance in agreement with previous direct measurements, but also previously unknown parameters such as the volume of the fluid meniscus and the bending stiffness of the tip. In addition to confirming the primary role of surface tension for insect adhesion, our investigation reveals marked differences in geometry and compliance between the three main kinds of seta tips in leaf beetles. © 2016 The Author(s).

Use of flow-diverting stents as salvage treatment following failed stent-assisted embolization of intracranial aneurysms.

PubMed

Heiferman, Daniel M; Billingsley, Joshua T; Kasliwal, Manish K; Johnson, Andrew K; Keigher, Kiffon M; Frudit, Michel E; Moftakhar, Roham; Lopes, Demetrius K

2016-07-01

Flow-diverting stents, including the Pipeline embolization device (PED) and Silk, have been beneficial in the treatment of aneurysms previously unable to be approached via endovascular techniques. Recurrent aneurysms for which stent-assisted embolization has failed are a therapeutic challenge, given the existing intraluminal construct with continued blood flow into the aneurysm. We report our experience using flow-diverting stents in the repair of 25 aneurysms for which stent-assisted embolization had failed. Nineteen (76%) of these aneurysms at the 12-month follow-up showed improved Raymond class occlusion, with 38% being completely occluded, and all aneurysms demonstrated decreased filling. One patient developed a moderate permanent neurologic deficit. Appropriate stent sizing, proximal and distal construct coverage, and preventing flow diverter deployment between the previously deployed stent struts are important considerations to ensure wall apposition and prevention of endoleak. Flow diverters are shown to be a reasonable option for treating previously stented recurrent cerebral aneurysms. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Influence of Beam Rotation on the Response of Cantilevered Flow Energy Harvesters Exploiting the Galloping Instability

NASA Astrophysics Data System (ADS)

Noel, James H.

Energy harvesters are scalable devices that generate microwatt to milliwatt power levels by scavenging energy from their ambient natural environment. Applications of such devices are numerous, ranging from wireless sensing to biomedical implants. A particular type of energy harvester is a device which converts the momentum of an incident fluid flow into electrical output by using flow-induced instabilities such as galloping, flutter, vortex shedding and wake galloping. Galloping flow energy harvesters (GFEHs), which represent the core of this thesis, consist of a prismatic tip body mounted on a long, thin cantilever beam fixed on a rigid base. When the bluff body is placed such that its leading edge faces a moving fluid, the flow separates at the edges of the leading face causing shear layers to develop behind the bluff face. The shear layer interacts with the surface area of the afterbody. An asymmetric condition in the shear layers causes a net lift which incites motion. This causes the beam to oscillate periodically at or near the natural frequency of the system. The periodic strain developed near the base of the oscillating beam is then transformed into electricity by attaching a piezoelectric layer to either side of the beam surface. This thesis focuses on characterizing the influence of the rotation of the beam tip on the response and output power of GFEHs. Previous modeling efforts of GFEHs usually adopt two simplifying assumptions. First, it is assumed that the tip rotation of the beam is arbitrarily small and hence can be neglected. Second, it is assumed that the quasi-steady assumption of the aerodynamic force can be adopted even in the presence of tip rotation. Although the validity of these two assumptions becomes debatable in the presence of finite tip rotations, which are common to occur in GFEHs, none the previous research studies have systematically addressed the influence of finite tip rotations on the validity of the quasi-steady assumption and the response of cantilevered flow energy harvesters. To this end, the first objective of this thesis is to investigate the influence of the tip rotation on the output power of energy harvesters under the quasi-steady assumption. It is shown that neglecting the tip rotation will cause significant over-prediction of the output power even for small tip rotations. This thesis further assesses the validity of the quasi-steady assumption of the aerodynamic force in the presence of tip rotations using extensive experiments. It is shown that the quasi-steady model fails to accurately predict the behavior of square and trapezoidal prisms mounted on a cantilever beam and undergoing galloping oscillations. In particular, it is shown that the quasi-steady model under-predicts the amplitude of oscillation because it fails to consider the effect of body rotation. Careful analysis of the experimental data indicates that, unlike the quasi-steady aerodynamic lift force which depends only on the angle of attack, the effective aerodynamic curve is a function of both the angle of attack and the upstream flow velocity when the effects of body rotation are included. Nonetheless, although the quasi-steady assumption fails, the remarkable result is that the overall structure of the aerodynamic model remains intact, permitting the use of aerodynamic force surfaces to capture the influence of tip rotation. The second objective of this thesis is to present an approach to optimize the geometry of the bluff body to improve the performance of flow energy harvesters. It is shown that attaching a splitter plate to the afterbody of the prism can improve the output power of the device by as much as 60% for some cases. By increasing the reattachment angle of the shear layer and producing additional flow recirculation bubbles, the extension of the body using the splitter plate increases the useful range of the galloping instability for energy harvesting.

Mobile Interspersed Repeats Are Major Structural Variants in the Human Genome

PubMed Central

Huang, Cheng Ran Lisa; Schneider, Anna M.; Lu, Yunqi; Niranjan, Tejasvi; Shen, Peilin; Robinson, Matoya A.; Steranka, Jared P.; Valle, David; Civin, Curt I.; Wang, Tao; Wheelan, Sarah J.; Ji, Hongkai; Boeke, Jef D.; Burns, Kathleen H.

2010-01-01

Summary Characterizing structural variants in the human genome is of great importance, but a genome wide analysis to detect interspersed repeats has not been done. Thus, the degree to which mobile DNAs contribute to genetic diversity, heritable disease, and oncogenesis remains speculative. We perform transposon insertion profiling by microarray (TIP-chip) to map human L1(Ta) retrotransposons (LINE-1 s) genome-wide. This identified numerous novel human L1(Ta) insertional polymorphisms with highly variant allelic frequencies. We also explored TIP-chip's usefulness to identify candidate alleles associated with different phenotypes in clinical cohorts. Our data suggest that the occurrence of new insertions is twice as high as previously estimated, and that these repeats are under-recognized as sources of human genomic and phenotypic diversity. We have just begun to probe the universe of human L1(Ta) polymorphisms, and as TIP-chip is applied to other insertions such as Alu SINEs, it will expand the catalog of genomic variants even further. PMID:20602999

Observation of an electrical signal from a single molecule

NASA Astrophysics Data System (ADS)

Aslan, Arooj; Shaheen, Noor; Dobiszewski, Kyle; Kanwal, Alokik; Farrow, Reginald; Thomas, Gordon

We have attached a folded protein molecule to the tip of a carbon nanotube using electrophoresis. We have then measured the electrons produced when the protein catalyzes a series of reactions. As an initial example of the reactions, we have used the catalysis by glucose-oxidase of glucose. We can show that the characteristic dynamic signals from the molecule scale with the glucose concentration. The molecule on the carbon nanotube tip is stable with respect to time under controlled conditions. The signals also indicate the glucose diffusion as its concentration is locally depleted at the nanotube by the catalysis. We use a second carbon nanotube with a laccase molecule on its tip to complete the circuit with an oxygen reaction. In a previous stage of this process, the other end of the nanotube is attached with a low-impedance electrical connection to a Ti thin film and the measuring circuitry. This work is an early step toward investigating the feasibility of an implantable glucose monitor to help treat diabetes.

Hawkmoths evaluate scenting flowers with the tip of their proboscis

PubMed Central

Haverkamp, Alexander; Yon, Felipe; Keesey, Ian W; Mißbach, Christine; Koenig, Christopher; Hansson, Bill S; Baldwin, Ian T

2016-01-01

Pollination by insects is essential to many ecosystems. Previously, we have shown that floral scent is important to mediate pollen transfer between plants (Kessler et al., 2015). Yet, the mechanisms by which pollinators evaluate volatiles of single flowers remained unclear. Here, Nicotiana attenuata plants, in which floral volatiles have been genetically silenced and its hawkmoth pollinator, Manduca sexta, were used in semi-natural tent and wind-tunnel assays to explore the function of floral scent. We found that floral scent functions to increase the fitness of individual flowers not only by increasing detectability but also by enhancing the pollinator's foraging efforts. Combining proboscis choice tests with neurophysiological, anatomical and molecular analyses we show that this effect is governed by newly discovered olfactory neurons on the tip of the moth's proboscis. With the tip of their tongue, pollinators assess the advertisement of individual flowers, an ability essential for maintaining this important ecosystem service. DOI: http://dx.doi.org/10.7554/eLife.15039.001 PMID:27146894

High-energy electron emission from metallic nano-tips driven by intense single-cycle terahertz pulses

PubMed Central

Li, Sha; Jones, R. R.

2016-01-01

Electrons ejected from atoms and subsequently driven to high energies in strong laser fields enable techniques from attosecond pulse generation to imaging with rescattered electrons. Analogous processes govern strong-field electron emission from nanostructures, where long wavelength radiation and large local field enhancements hold the promise for producing electrons with substantially higher energies, allowing for higher resolution time-resolved imaging. Here we report on the use of single-cycle terahertz pulses to drive electron emission from unbiased nano-tips. Energies exceeding 5 keV are observed, substantially greater than previously attained at higher drive frequencies. Despite large differences in the magnitude of the respective local fields, we find that the maximum electron energies are only weakly dependent on the tip radius, for 10 nm

Energetic and entropic components of the Tolman length for mW and TIP4P/2005 water nanodroplets

NASA Astrophysics Data System (ADS)

Joswiak, Mark N.; Do, Ryan; Doherty, Michael F.; Peters, Baron

2016-11-01

The surface free energy of a droplet is approximately γ ( R ) = γ ( ∞ ) ( 1 - 2 δ / R ) , with R being the droplet radius and δ being the Tolman length. Here we use the mitosis method to compute δ = - 0.56 ± 0.1 Å at 300 K for mW water, indicating that γ ( R ) increases as the droplet size decreases. The computed Tolman length agrees quite well with a previous study of TIP4P/2005 water. We also decompose the size-dependent surface free energy into energetic and entropic contributions for the mW and TIP4P/2005 force fields. Despite having similar Tolman lengths, the energy-entropy decompositions are very different for the two force fields. We discuss critical assumptions which lead to these findings and their relation to experiments on the nucleation of water droplets. We also discuss surface broken bonds and structural correlations as possible explanations for the energetic and entropic contributions.

Lifeact-mEGFP Reveals a Dynamic Apical F-Actin Network in Tip Growing Plant Cells

PubMed Central

Hepler, Peter K.; Bezanilla, Magdalena

2009-01-01

Background Actin is essential for tip growth in plants. However, imaging actin in live plant cells has heretofore presented challenges. In previous studies, fluorescent probes derived from actin-binding proteins often alter growth, cause actin bundling and fail to resolve actin microfilaments. Methodology/Principal Findings In this report we use Lifeact-mEGFP, an actin probe that does not affect the dynamics of actin, to visualize actin in the moss Physcomitrella patens and pollen tubes from Lilium formosanum and Nicotiana tobaccum. Lifeact-mEGFP robustly labels actin microfilaments, particularly in the apex, in both moss protonemata and pollen tubes. Lifeact-mEGFP also labels filamentous actin structures in other moss cell types, including cells of the gametophore. Conclusions/Significance Lifeact-mEGFP, when expressed at optimal levels does not alter moss protonemal or pollen tube growth. We suggest that Lifeact-mEGFP represents an exciting new versatile probe for further studies of actin's role in tip growing plant cells. PMID:19478943

Stimulated Raman spectroscopy and nanoscopy of molecules using near field photon induced forces without resonant electronic enhancement gain

NASA Astrophysics Data System (ADS)

Tamma, Venkata Ananth; Huang, Fei; Nowak, Derek; Kumar Wickramasinghe, H.

2016-06-01

We report on stimulated Raman spectroscopy and nanoscopy of molecules, excited without resonant electronic enhancement gain, and recorded using near field photon induced forces. Photon-induced interaction forces between the sharp metal coated silicon tip of an Atomic Force Microscope (AFM) and a sample resulting from stimulated Raman excitation were detected. We controlled the tip to sample spacing using the higher order flexural eigenmodes of the AFM cantilever, enabling the tip to come very close to the sample. As a result, the detection sensitivity was increased compared with previous work on Raman force microscopy. Raman vibrational spectra of azobenzene thiol and l-phenylalanine were measured and found to agree well with published results. Near-field force detection eliminates the need for far-field optical spectrometer detection. Recorded images show spatial resolution far below the optical diffraction limit. Further optimization and use of ultrafast pulsed lasers could push the detection sensitivity towards the single molecule limit.

Stimulated Raman spectroscopy and nanoscopy of molecules using near field photon induced forces without resonant electronic enhancement gain

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

Tamma, Venkata Ananth; Huang, Fei; Kumar Wickramasinghe, H., E-mail: hkwick@uci.edu

We report on stimulated Raman spectroscopy and nanoscopy of molecules, excited without resonant electronic enhancement gain, and recorded using near field photon induced forces. Photon-induced interaction forces between the sharp metal coated silicon tip of an Atomic Force Microscope (AFM) and a sample resulting from stimulated Raman excitation were detected. We controlled the tip to sample spacing using the higher order flexural eigenmodes of the AFM cantilever, enabling the tip to come very close to the sample. As a result, the detection sensitivity was increased compared with previous work on Raman force microscopy. Raman vibrational spectra of azobenzene thiol andmore » l-phenylalanine were measured and found to agree well with published results. Near-field force detection eliminates the need for far-field optical spectrometer detection. Recorded images show spatial resolution far below the optical diffraction limit. Further optimization and use of ultrafast pulsed lasers could push the detection sensitivity towards the single molecule limit.« less

Aerodynamic Comparison of Hyper-Elliptic Cambered Span (HECS) Wings with Conventional Configurations

NASA Technical Reports Server (NTRS)

Lazos, Barry S.; Visser, Kenneth D.

2006-01-01

An experimental study was conducted to examine the aerodynamic and flow field characteristics of hyper-elliptic cambered span (HECS) wings and compare results with more conventional configurations used for induced drag reduction. Previous preliminary studies, indicating improved L/D characteristics when compared to an elliptical planform prompted this more detailed experimental investigation. Balance data were acquired on a series of swept and un-swept HECS wings, a baseline elliptic planform, two winglet designs and a raked tip configuration. Seven-hole probe wake surveys were also conducted downstream of a number of the configurations. Wind tunnel results indicated aerodynamic performance levels of all but one of the HECS wings exceeded that of the other configurations. The flow field data surveys indicate the HECS configurations displaced the tip vortex farther outboard of the wing than the Baseline configuration. Minimum drag was observed on the raked tip configuration and it was noted that the winglet wake lacked the cohesive vortex structure present in the wakes of the other configurations.

Delayed Infective Endocarditis with Mycotic Aneurysm Rupture below the Mechanical Valved Conduit after the Bentall Procedure

PubMed Central

Chen, Mei-Ling; Chen, Michael Y.; Yin, Wei-Hsian; Wei, Jeng; Wang, Ji-Hung

2014-01-01

The Bentall procedure is the gold standard for treating aortic dissection complicated with valvular and ascending aorta disease. Recent results for this procedure have been excellent; nearly 100% of patients remain free of infective endocarditis in long-term follow-up. We report a case of delayed Streptococcus agalactiae infective endocarditis complicated by mycotic aneurysm in a man who had undergone the Bentall procedure with a mechanical valve conduit 15 years previously. The mycotic aneurysm was located in the remnant aortic root, below the mechanical valve conduit, and later ruptured into the right atrium. The patient was treated conservatively and survived the acute period. Later, the aortic root defect was repaired successfully by means of a hybrid technique using a Amplatzer duct occluder. PMID:27122809

Giant and thrombosed left ventricular aneurysm

PubMed Central

de Agustin, Jose Alberto; de Diego, Jose Juan Gomez; Marcos-Alberca, Pedro; Rodrigo, Jose Luis; Almeria, Carlos; Mahia, Patricia; Luaces, Maria; Garcia-Fernandez, Miguel Angel; Macaya, Carlos; de Isla, Leopoldo Perez

2015-01-01

Left ventricular aneurysms are a frequent complication of acute extensive myocardial infarction and are most commonly located at the ventricular apex. A timely diagnosis is vital due to the serious complications that can occur, including heart failure, thromboembolism, or tachyarrhythmias. We report the case of a 78-year-old male with history of previous anterior myocardial infarction and currently under evaluation by chronic heart failure. Transthoracic echocardiogram revealed a huge thrombosed and calcified anteroapical left ventricular aneurysm. Coronary angiography demonstrated that the left anterior descending artery was chronically occluded, and revealed a big and spherical mass with calcified borders in the left hemithorax. Left ventriculogram confirmed that this spherical mass was a giant calcified left ventricular aneurysm, causing very severe left ventricular systolic dysfunction. The patient underwent cardioverter-defibrillator implantation for primary prevention. PMID:26225205

Impending rupture of saphenous vein graft aneurysm with floating fractured bare metal stent treated by coil embolization and covered stent implantation.

PubMed

Kodama, Atsuko; Kurita, Tairo; Kato, Osamu; Suzuki, Takahiko

2016-11-01

Aneurysmal degeneration of a saphenous vein graft (SVG) is a rare, but potentially fatal complication of coronary artery bypass graft (CABG) surgery. In this case report, a patient that had undergone prior CABG surgery and bare metal stent (BMS) implantation at the site of a stenotic SVG lesion presented at our hospital with chest pain, and an SVG aneurysm was detected at the previous BMS implantation site. In addition, the implanted BMS was fractured and floating in the SVG aneurysm. The SVG aneurysm was successfully occluded by percutaneous intervention, using a combination of distal covered stent deployment at the site of the anastomosis between the native coronary artery and the SVG and proximal coil embolization of the aneurysm.

An Experimental Investigation of the Flow Physics Associated With End Wall Losses and Large Rotor Tip Clearances as Found in the Rear Stages of a High Pressure Compressor

NASA Technical Reports Server (NTRS)

Berdanier, Reid A.; Key, Nicole L.

2015-01-01

The focus of this work was to characterize the fundamental flow physics and the overall performance effects due to increased rotor tip clearance heights in axial compressors. Data have been collected in the three-stage axial research compressor at Purdue University with a specific focus on analyzing the multistage effects resulting from the tip leakage flow. Three separate rotor tip clearance heights were studied with nominal tip clearance heights of 1.5%, 3.0%, and 4.0% based on a constant annulus height. Overall compressor performance was investigated at four corrected speedlines (100%, 90%, 80%, and 68%) for each of the three tip clearance configurations using total pressure and total temperature rakes distributed throughout the compressor. The results have confirmed results from previous authors showing a decrease of total pressure rise, isentropic efficiency, and stall margin which is approximately linear with increasing tip clearance height. The stall inception mechanisms have also been evaluated at the same corrected speeds for each of the tip clearance configurations. Detailed flow field measurements have been collected at two loading conditions, nominal loading (NL) and high loading (HL), on the 100% corrected speedline for the smallest and largest tip clearance heights (1.5% and 4.0%). Steady detailed radial traverses of total pressure at the exit of each stator row have been supported by flow visualization techniques to identify regions of flow recirculation and separation. Furthermore, detailed radial traverses of time-resolved total pressures at the exit of each rotor row have been measured with a fast-response pressure probe. These data have helped to quantify the size of the leakage flow at the exit of each rotor. Thermal anemometry has also been implemented to evaluate the time-resolved three-dimensional components of velocity throughout the compressor and calculate blockage due to the rotor tip leakage flow throughout the compressor. These measurements have also been used to calculate streamwise vorticity. Time-resolved static pressure measurements have been collected over the rotor tips for all rotors with each of the three tip clearance configurations for up to five loading conditions along the 100% corrected speedline using fast-response piezoresistive pressure sensors. These time-resolved static pressure measurements, as well as the time-resolved total pressures and velocities have helped to reveal a profound influence of the upstream stator vane on the size and shape of the rotor tip leakage flow. Finally, a novel particle image velocimetry (PIV) technique has been developed as a proof-of- concept. In contrast to PIV methods that have been typically been utilized for turbomachinery applications in the past, the method used for this study introduced the laser light through the same access window that was also used to image the flow. This new method addresses potential concerns related to the intrusive laser-introducing techniques that have typically been utilized by other authors in the past. Ultimately, the data collected for this project represent a unique data set which contributes to build a better understanding of the tip leakage flow field and its associated loss mechanisms. These data will facilitate future engine design goals leading to small blade heights in the rear stages of high pressure compressors and aid in the development of new blade designs which are desensitized to the performance penalties attributed to rotor tip leakage flows.

Earth Observations taken by the Expedition 27 Crew

NASA Image and Video Library

2011-03-20

ISS027-E-006501 (20 March 2011) --- A low pressure system in the eastern North Pacific Ocean is featured in this image photographed by an Expedition 27 crew member in the Cupola of the International Space Station. This vigorous low pressure system has started to occlude?a process associated with separation of warm air from the cyclone?s center at the Earth?s surface. This view shows the arc of strong convection beyond the center of the low pressure, formed as the low occludes when the cold front overtakes the warm front. This occurs around more mature low pressure areas, later in the process of the system?s life-cycle.

Surgical repair of tricuspid valve leaflet tear following percutaneous closure of perimembranous ventricular septal defect using Amplatzer duct occluder I: Report of two cases

PubMed Central

Kuwelker, Saatchi Mahesh; Shetty, Devi Prasad; Dalvi, Bharat

2017-01-01

Tricuspid valve (TV) injury following transcatheter closure of perimembranous ventricular septal defect (PMVSD) with Amplatzer ductal occluder I (ADO I), requiring surgical repair, is rare. We report two cases of TV tear involving the anterior and septal leaflets following PMVSD closure using ADO I. In both the patients, the subvalvular apparatus remained unaffected. The patients presented with severe tricuspid regurgitation (TR) 6 weeks and 3 months following the device closure. They underwent surgical repair with patch augmentation of the TV leaflets. Postoperatively, both are asymptomatic with a mild residual TR. PMID:28163430

Process for producing wurtzitic or cubic boron nitride

DOEpatents

Holt, J.B.; Kingman, D.D.; Bianchini, G.M.

1992-04-28

Disclosed is a process for producing wurtzitic or cubic boron nitride comprising the steps of: [A] preparing an intimate mixture of powdered boron oxide, a powdered metal selected from the group consisting of magnesium or aluminum, and a powdered metal azide; [B] igniting the mixture and bringing it to a temperature at which self-sustaining combustion occurs; [C] shocking the mixture at the end of the combustion thereof with a high pressure wave, thereby forming as a reaction product, wurtzitic or cubic boron nitride and occluded metal oxide; and, optionally [D] removing the occluded metal oxide from the reaction product. Also disclosed are reaction products made by the process described.

Process for producing wurtzitic or cubic boron nitride

DOEpatents

Holt, J. Birch; Kingman, deceased, Donald D.; Bianchini, Gregory M.

1992-01-01

Disclosed is a process for producing wurtzitic or cubic boron nitride comprising the steps of: [A] preparing an intimate mixture of powdered boron oxide, a powdered metal selected from the group consisting of magnesium or aluminum, and a powdered metal azide; [B] igniting the mixture and bringing it to a temperature at which self-sustaining combustion occurs; [C] shocking the mixture at the end of the combustion thereof with a high pressure wave, thereby forming as a reaction product, wurtzitic or cubic boron nitride and occluded metal oxide; and, optionally [D] removing the occluded metal oxide from the reaction product. Also disclosed are reaction products made by the process described.

Transcatheter closure of large patent ductus arteriosus using custom made devices.

PubMed

Rohit, Manoj Kumar; Gupta, Ankur

2017-05-01

There has been a paradigm shift in the transcatheter closure of patent ductus arteriosus (PDA) over the last 45 years. With the availability of various coils, plugs and occluders, PDA of almost all shapes and sizes are amenable to transcatheter closure. However, very large PDA diagnosed late in life are being referred for surgical closure in the absence of availability of large size devices, especially in developing countries. In this case series, we have described four patients with large PDA, three of which were closed by transcatheter custom made PDA occluders. © 2014 Wiley Periodicals, Inc. © 2014 Wiley Periodicals, Inc.

The off-label use of the Amplatzer muscular VSD occluder for large patent ductus arteriosus: a case report and review.

PubMed

Cubeddu, Roberto J; Babin, Ivan; Inglessis, Ignacio

2014-07-01

A percutaneous approach to the closure of patent ductus arteriosus (PDA) is the preferred procedure in the majority of cases. However, there is little experience with percutaneous closure of unusually large PDA. We report the case of a 28-year-old female with moderate left ventricular dilation and pulmonary hypertension resulting from a large 16 mm PDA. Percutaneous closure was successfully performed using an off-label Amplatzer muscular ventricular septal defect occluder after intravascular ultrasound assessment. Technical challenges, including accurate assessment of defect size and device selection are exemplified along with a comprehensive overview of the available literature.

Intuitive physical reasoning about occluded objects by inexperienced chicks

PubMed Central

Chiandetti, Cinzia; Vallortigara, Giorgio

2011-01-01

Questions concerning the role of nature and nurture in higher cognition appear to be intractable if one restricts one's attention to development in humans. However, in other domains, such as sensory development, much information has been gained from controlled rearing studies with animals. Here, we used a similar experimental strategy to investigate intuitive reasoning about occluded objects. Newborn domestic chicks (Gallus gallus) were reared singly with a small object that became their social partner. They were then accustomed to rejoin such an imprinting object when it was made to move and disappear behind either one of two identical opaque screens. After disappearance of the imprinting object, chicks were faced with two screens of different slants, or of different height or different width, which may or may not have been compatible with the presence of the imprinting object hidden beneath/behind them. Chicks consistently chose the screen of slant/height/width compatible with the presence of the object beneath/behind it. Preventing chicks from touching and pecking at the imprinting object before testing did not affect the results, suggesting that intuitive reasoning about physical objects is largely independent of specific experience of interaction with objects and of objects' occluding events. PMID:21270036

Perceiving patterns of play in dynamic sport tasks: investigating the essential information underlying skilled performance.

PubMed

Willams, A Mark; Hodges, Nicola J; North, Jamie S; Barton, Gabor

2006-01-01

The perceptual-cognitive information used to support pattern-recognition skill in soccer was examined. In experiment 1, skilled players were quicker and more accurate than less-skilled players at recognising familiar and unfamiliar soccer action sequences presented on film. In experiment 2, these action sequences were converted into point-light displays, with superficial display features removed and the positions of players and the relational information between them made more salient. Skilled players were more accurate than less-skilled players in recognising sequences presented in point-light form, implying that each pattern of play can be defined by the unique relations between players. In experiment 3, various offensive and defensive players were occluded for the duration of each trial in an attempt to identify the most important sources of information underpinning successful performance. A decrease in response accuracy was observed under occluded compared with non-occluded conditions and the expertise effect was no longer observed. The relational information between certain key players, team-mates and their defensive counterparts may provide the essential information for effective pattern-recognition skill in soccer. Structural feature analysis, temporal phase relations, and knowledge-based information are effectively integrated to facilitate pattern recognition in dynamic sport tasks.

Estimation of stereovision in conditions of blurring simulation

NASA Astrophysics Data System (ADS)

Krumina, Gunta; Ozolinsh, Maris; Lacis, Ivazs; Lyakhovetskii, Vsevolod

2005-08-01

The aim of this study was to evaluate the simulation of eye pathologies, such as amblyopia and cataracts, to estimate the stereovision in artificial conditions, and to compare the results on the stereothreshold obtained in artificial and real- pathologic conditions. Characteristic of the above-mentioned real-life forms of a reduced vision is a blurred image in one of the eyes. The blurring was simulated by (i) defocusing, (ii) blurred stimuli on the screen, and (iii) occluding of an eye with PLZT or PDLC plates. When comparing the methods, two parameters were used: the subject's visual acuity and the modulation depth of the image. The eye occluder method appeared to systematically provide higher stereothreshold values than the rest of the methods. The PLZT and PDLC plates scattered more in the blue and decreased the contrast of the stimuli when the blurring degree was increased. In the eye occluder method, the stereothreshold increased faster than in the defocusation and monitor stimuli methods when the visual acuity difference was higher than 0.4. It has been shown that the PLZT and PDLC plates are good optical phantoms for the simulation of a cataract, while the defocusation and monitor stimuli methods are more suitable for amblyopia.

Electronic eye occluder with time-counting and reflection control

NASA Astrophysics Data System (ADS)

Karitans, V.; Ozolinsh, M.; Kuprisha, G.

2008-09-01

In pediatric ophthalmology 2 - 3 % of all the children are impacted by a visual pathology - amblyopia. It develops if a clear image isn't presented to the retina during an early stage of the development of the visual system. A common way of treating this pathology is to cover the better-seeing eye to force the "lazy" eye to learn seeing. However, children are often reluctant to wear such an occluder because they are ashamed or simply because they find it inconvenient. This fact requires to find a way how to track the regime of occlusion because results of occlusion is a hint that the actual regime of occlusion isn't that what the optometrist has recommended. We design an electronic eye occluder that allows to track the regime of eye occlusion. We employ real-time clock DS1302 providing time information from seconds to years. Data is stored in the internal memory of the CPU (EEPROM). The MCU (PIC16F676) switches on only if a mechanical switch is closed and temperature has reached a satisfactory level. The occlusion is registered between time moments when the infrared signal appeared and disappeared.

Feasibility of laser-targeted photoocclusion of the choriocapillary layer in rats.

PubMed

Asrani, S; Zou, S; D'Anna, S; Lutty, G; Vinores, S A; Goldberg, M F; Zeimer, R

1997-12-01

A new method, laser-targeted photoocclusion, was developed to occlude choroidal neovascularization while minimizing damage to the overlying retina. The ability to occlude normal choriocapillary layer in rats was evaluated as a first test of the feasibility of treating choroidal neovascularization with this method. A photosensitive agent, aluminum phthalocyanine tetrasulfonate, encapsulated in heat-sensitive liposomes, was administered intravenously along with carboxyfluorescein liposomes. A low-power argon laser (retinal power density of 5.7 W/cm2) locally released a photosensitizer bolus, monitored by the simultaneous release of carboxyfluorescein. A diode laser (operating at 675 nm with a retinal power density of 0.27 W/cm2) activated the photosensitizer with its release. Vessels in the choriocapillary layer were occluded at day 3 after laser treatment and remained unchanged during the 30-day follow-up. Larger choroidal vessels and retinal capillaries remained perfused. Control experiments excluded possible effects of heat or activation of free photosensitizer. Pilot histologic studies showed no damage to the retinal pigment epithelium. Laser-targeted photoocclusion caused selective occlusion of normal choriocapillaries while sparing overlying retinal pigment epithelium and retinal vessels. The method has potential as a treatment of choroidal neovascularization that may minimize iatrogenic loss of vision.

Effects of transcatheter closure of Fontan fenestration on exercise tolerance. kidecho@yahoo.com.

PubMed

Momenah, Tarek S; Eltayb, Haifa; Oakley, Reida El; Qethamy, Howeida Al; Faraidi, Yahya Al

2008-05-01

Baffle fenestration is associated with a significantly better outcome in standard and high-risk patients undergoing completion of Fontan. We report the effects of subsequent transcatheter closure of fenestration on exercise capacity and oxygen saturation. Sixteen patients with a mean age of 10.3 years underwent Amplatzer septal occluder (ASO) device transcatheter closure of Fontan fenestration. All had a fenestrated Fontan operation 6 month to 8 years prior to the procedure. A stress test was performed before and after device closure of fenestration in 14 patients (2 patients did not tolerate stress test before the procedure). The fenestrations in all patients were successfully occluded with the use of the Amplatzer device occluder. No complications occurred during or after the procedure. O2 saturation increased from a mean 85.1 +/- 7.89% to 94.5 +/- 3.63% (p < 0.01) at rest and from 66.2 +/- 12.86% to 87.2 +/- 8.64% (p < 0.01) following exercise. Exercise duration has also increased from 8.22 +/- 2.74 min to 10.29 +/- 1.91 min (p < 0.05). Transcatheter closure of Fontan fenestration increases the duration of exercise capacity and increases O2 saturation at rest and after exercise.

Cochlear excitation by the near-field component during stimulation through the partially occluded round window

NASA Astrophysics Data System (ADS)

Weddell, Thomas D.; Yarin, Yury M.; Drexl, Markus; Russell, Ian J.; Elliott, Stephen J.; Lukashkin, Andrei N.

2015-12-01

The round window membrane (RW) provides pressure relief when the cochlea is excited by sound. While normal function of the RW is important for effective stimulation of the cochlea through the conventional oval window route, the cochlea can be stimulated successfully in non-conventional ways (e.g. through bone conduction, through the RW, and through perforations in the cochlea's apical turn). We report measurements of cochlear function from guinea pigs when the cochlea was stimulated at acoustic frequencies by movements of a miniature magnet which partially occluded the RW. Neural response latencies to acoustic and RW stimulation were similar and taken to indicate that both means of stimulation resulted in the generation of conventional travelling waves along the cochlear partition. It was concluded that the relatively high impedance of the ossicles, as seen from the cochlea, enabled the region of the RW not occluded by the magnet, to act as a pressure shunt during RW stimulation. We propose that travelling waves, similar to those due to acoustic far-field pressure changes, are driven by a jet-like, near-field component of a complex fluid-pressure field, which is generated by the magnetically vibrated RW.

Influence of adequate pelvic floor muscle contraction on the movement of the coccyx during pelvic floor muscle training.

PubMed

Fujisaki, Akiko; Shigeta, Miwa; Shimoinaba, Misa; Yoshimura, Yasukuni

2018-04-01

[Purpose] Pelvic floor muscle training is a first-line therapy for female stress urinary incontinence. Previous studies have suggested that the coccyx tip moves ventrally and cranially during pelvic floor muscle contraction. The study aimed to elucidate the influence of adequate pelvic floor muscle contraction on coccyx movement. [Subjects and Methods] Sixty-three females (57 patients with stress urinary incontinence and additional 6 healthy volunteers) were enrolled. Using magnetic resonance imaging, coccyx movement was evaluated during pelvic floor muscle contraction and strain. An adequate contraction was defined as a contraction with good Oxford grading scale [≥3] and without inadequate muscle substitution patterns. [Results] Inadequate muscle substitution patterns were observed in 33 participants (52.4%). No significant difference was observed in the movement of the coccyx tip in the ventrodorsal direction between females with and without inadequate muscle substitution patterns. However, a significant increase in the movement of the coccyx tip in the cranial direction was detected in the group without inadequate muscle substitution patterns. Compared to participants with inadequate pelvic floor muscle contraction, those who had adequate pelvic floor muscle contraction exhibited significantly increased cranial movement of the coccyx. [Conclusion] Adequate pelvic floor muscle contraction can produce cranial movement of the coccyx tip.

Determining cyclic corrosion cracking resistance for titanium alloys with allowance for electrochemical conditions at the fatigue corrosion crack tip

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

Panasyuk, V.V.; Ratich, L.V.; Petranyuk, I.Ya.

1994-08-01

Published data are examined on how various factors affect fatigue crack growth rates. Basic diagrams have been constructed for the cyclic cracking resistance in Ti-6Al-4V and Ti-6Al-2Sn alloys in air, distilled water, and 3.5% NaCl for use in working-life calculations. Appropriate heat treatment can produce two microstructures in a titanium alloy, one of which has the largest cyclic cracking resistance, while in the second, the cracks grow at the lowest rate. The cyclic corrosion cracking resistance for a titanium alloy should be determined in relation to the state of stress and strain and to the electrochemical conditions at the corrosionmore » fatigue crack tip, while the variations in fatigue crack growth rate for a given stress intensity factor in a corrosive medium are due to differing electrochemical conditions at the crack tip during the testing on different specimens. Basic diagrams can be derived for titanium alloys by using a physically sound methodology developed previously for steels, which is based on invariant diagrams for cyclic cracking resistance in air and in the corresponding medium, which can be constructed in relation to extremal working and electrochemical conditions at corrosion-fatigue crack tips.« less

High heat flux Langmuir probe array for the DIII-D divertor platesa)

NASA Astrophysics Data System (ADS)

Watkins, J. G.; Taussig, D.; Boivin, R. L.; Mahdavi, M. A.; Nygren, R. E.

2008-10-01

Two modular arrays of Langmuir probes designed to handle a heat flux of up to 25 MW/m2 for 10 s exposures have been installed in the lower divertor target plates of the DIII-D tokamak. The 20 pyrolytic graphite probe tips have more than three times higher thermal conductivity and 16 times larger mass than the original DIII-D isotropic graphite probes. The probe tips have a fixed 12.5° surface angle to distribute the heat flux more uniformly than the previous 6 mm diameter domed collectors and a symmetric "rooftop" design to allow operation with reversed toroidal magnetic field. A large spring-loaded contact area improves heat conduction from each probe tip through a ceramic insulator into a cooled graphite divertor floor tile. The probe tips, brazed to molybdenum foil to ensure good electrical contact, are mounted in a ceramic tray for electrical isolation and reliable cable connections. The new probes are located 1.5 cm radially apart in a staggered arrangement near the entrance to the lower divertor pumping baffle and are linearly spaced 3 cm apart on the shelf above the in-vessel cryopump. Typical target plate profiles of Jsat, Te, and Vf with 4 mm spatial resolution are shown.

Thermo-solutal and kinetic modes of stable dendritic growth with different symmetries of crystalline anisotropy in the presence of convection

NASA Astrophysics Data System (ADS)

Alexandrov, Dmitri V.; Galenko, Peter K.; Toropova, Lyubov V.

2018-01-01

Motivated by important applications in materials science and geophysics, we consider the steady-state growth of anisotropic needle-like dendrites in undercooled binary mixtures with a forced convective flow. We analyse the stable mode of dendritic evolution in the case of small anisotropies of growth kinetics and surface energy for arbitrary Péclet numbers and n-fold symmetry of dendritic crystals. On the basis of solvability and stability theories, we formulate a selection criterion giving a stable combination between dendrite tip diameter and tip velocity. A set of nonlinear equations consisting of the solvability criterion and undercooling balance is solved analytically for the tip velocity V and tip diameter ρ of dendrites with n-fold symmetry in the absence of convective flow. The case of convective heat and mass transfer mechanisms in a binary mixture occurring as a result of intensive flows in the liquid phase is detailed. A selection criterion that describes such solidification conditions is derived. The theory under consideration comprises previously considered theoretical approaches and results as limiting cases. This article is part of the theme issue `From atomistic interfaces to dendritic patterns'. This article is part of the theme issue `From atomistic interfaces to dendritic patterns'.

Influence of the State of the Tungsten Tip on STM Topographic Images of SnSe Surfaces

NASA Astrophysics Data System (ADS)

Ly, Trinh Thi; Kim, Jungdae

2018-03-01

Tin selenide (SnSe) has recently attracted significant attention because of its excellent thermoelectric properties with a figure of merit (ZT) of 2.6. Previous scanning tunneling microscopy (STM) studies of SnSe surfaces showed that only Sn atoms are resolved in topographic images due to the dominant contribution of the Sn 5 p z states in tunneling. However, when the state of the tungsten (W) tip changes from a typical four-lobe d state such as d xy or {d_{{x^2} - {y^2}}} to a two-lobe {d_{{z^2}}} state, the atomic features observed on the SnSe surface in STM topography can be dramatically altered. In this report, we present the results of a systematic study on the influence of the W tip's states on the STM images of SnSe surfaces. Sn atoms are observed with much stronger corrugation amplitude and smaller apparent radius when the tip is in a {d_{{z^2}}} state. In addition, the atomic features of the Se atoms become visible because of the sharply focused shape of the W {d_{{z^2}}} state. We expect our results to provide important information for establishing a better understanding of the microscopic nature of SnSe surfaces.

Study of potential aerodynamic benefits from spanwise blowing at wingtip. Ph.D. Thesis - George Washington Univ., 1992

NASA Technical Reports Server (NTRS)

Mineck, Raymond E.

1995-01-01

Comprehensive experimental and analytical studies have been conducted to assess the potential aerodynamic benefits from spanwise blowing at the tip of a moderate-aspect-ratio swept wing. Previous studies on low-aspect-ratio wings indicated that blowing from the wingtip can diffuse the tip vortex and displace it outward. The diffused and displaced vortex will induce a smaller downwash at the wing, and consequently the wing will have increased lift and decreased induced drag at a given angle of attack. Results from the present investigation indicated that blowing from jets with a short chord had little effect on lift or drag, but blowing from jets with a longer chord increased lift near the tip and reduced drag at low Mach numbers. A Navier-Stokes solver with modified boundary conditions at the tip was used to extrapolate the results to a Mach number of 0.72. Calculations indicated that lift and drag increase with increasing jet momentum coefficient. Because the momentum of the jet is typically greater than the reduction in the wing drag and the increase in the wing lift due to spanwise blowing is small, spanwise blowing at the wingtip does not appear to be a practical means of improving the aerodynamic efficiency of moderate-aspectratio swept wings at high subsonic Mach numbers.

Arcjet Cathode Phenomena

NASA Technical Reports Server (NTRS)

Curran, Francis M.; Haag, Thomas W.; Raquet, John F.

1989-01-01

Cathode tips made from a number of different materials were tested in a modular arcjet thruster in order to examine cathode phenomena. Periodic disassembly and examination, along with the data collected during testing, indicated that all of the tungsten-based materials behaved similarly despite the fact that in one of these samples the percentage of thorium oxide was doubled and another was 25 percent rhenium. The mass loss rate from a 2 percent thoriated rhenium cathode was found to be an order of magnitude greater than that observed using 2 percent thoriated tungsten. Detailed analysis of one of these cathode tips showed that the molten crater contained pure tungsten to a depth of about 150 microns. Problems with thermal stress cracking were encountered in the testing of a hafnium carbide tip. Post test analysis showed that the active area of the tip had chemically reacted with the propellant. A 100 hour continuous test was run at about 1 kW. Post test analysis revealed no dendrite formation, such as observed in a 30 kW arcjet lifetest, near the cathode crater. The cathodes from both this test and a previously run 1000 hour cycled test displayed nearly identical arc craters. Data and calculations indicate that the mass losses observed in testing can be explained by evaporation.

Arcjet cathode phenomena

NASA Technical Reports Server (NTRS)

Curran, Francis M.; Haag, Thomas W.; Raquet, John F.

1989-01-01

Cathode tips made from a number of different materials were tested in a modular arcjet thruster in order to examine cathode phenomena. Periodic disassembly and examination, along with the data collected during testing, indicated that all of the tungsten-based materials behaved similarly despite the fact that in one of these samples the percentage of thorium oxide was doubled and another was 25 percent rhenium. The mass loss rate from a 2 percent thoriated rhenium cathode was found to be an order of magnitude greater than that observed using 2 percent thoriated tungsten. Detailed analysis of one of these cathode tips showed that the molten crater contained pure tungsten to a depth of about 150 microns. Problems with thermal stress cracking were encountered in the testing of a hafnium carbide tip. Post test analysis showed that the active area of the tip had chemically reacted with the propellant. A 100 hour continuous test was run at about 1 kW. Post test analysis revealed no dendrite formation, such as observed in a 30 kW arcjet lifetest, near the cathode crater. The cathodes from both this test and a previously run 1000 hour cycled test displayed nearly identical arc craters. Data and calculations indicate that the mass losses observed in testing can be explained by evaporation.

Experimental and Numerical Analysis of Fracture in 41Cr4 Steel - Issues of the Stationary Cracks

NASA Astrophysics Data System (ADS)

Graba, M.

2018-02-01

This paper analyzes the process of fracture in 41Cr4 steel on the basis of experimental and numerical data obtained for non-propagating cracks. The author's previous and latest experimental results were used to determine the apparent crack initiation moment and fracture toughness for the material under plane strain conditions. Numerical simulations were carried out to assess changes in the J-integral, the crack tip opening displacement, the size of the plastic region and the distribution of stresses around the crack tip. A complex numerical analysis based on the true stress-strain curve was performed to determine the behavior of 41Cr4 steel under increasing external loads.

National Agricultural Statistics Service (NASS): Agricultural Chemical Use

Science.gov Websites

Management Agricultural Chemical Use Database Search Tips Usage Search | US Maps | Graphical Reports effort among USDA, the USDA Regional Pest Management Centers and the NSF Center for Integrated Pest Management (CIPM). All data available have been previously published by NASS and have been consolidated at

Some Pragmatic Tips for Dealing with Clinical Uncertainty

ERIC Educational Resources Information Center

Ratner, Nan Bernstein

2011-01-01

Purpose: This article proposes some recommendations to enable clinicians to balance certainty and uncertainty when evaluating the currency and effectiveness of their treatment approaches. Method: I offer the following advice: (a) Question the authority of the information previously learned in one's career; (b) be cognizant of what we do not yet…

Cytokinesis-Based Constraints on Polarized Cell Growth in Fission Yeast

PubMed Central

Bohnert, K. Adam; Gould, Kathleen L.

2012-01-01

The rod-shaped fission yeast Schizosaccharomyces pombe, which undergoes cycles of monopolar-to-bipolar tip growth, is an attractive organism for studying cell-cycle regulation of polarity establishment. While previous research has described factors mediating this process from interphase cell tips, we found that division site signaling also impacts the re-establishment of bipolar cell growth in the ensuing cell cycle. Complete loss or targeted disruption of the non-essential cytokinesis protein Fic1 at the division site, but not at interphase cell tips, resulted in many cells failing to grow at new ends created by cell division. This appeared due to faulty disassembly and abnormal persistence of the cell division machinery at new ends of fic1Δ cells. Moreover, additional mutants defective in the final stages of cytokinesis exhibited analogous growth polarity defects, supporting that robust completion of cell division contributes to new end-growth competency. To test this model, we genetically manipulated S. pombe cells to undergo new end take-off immediately after cell division. Intriguingly, such cells elongated constitutively at new ends unless cytokinesis was perturbed. Thus, cell division imposes constraints that partially override positive controls on growth. We posit that such constraints facilitate invasive fungal growth, as cytokinesis mutants displaying bipolar growth defects formed numerous pseudohyphae. Collectively, these data highlight a role for previous cell cycles in defining a cell's capacity to polarize at specific sites, and they additionally provide insight into how a unicellular yeast can transition into a quasi-multicellular state. PMID:23093943

Network formation and gelation in telechelic star polymers

NASA Astrophysics Data System (ADS)

Wadgaonkar, Indrajit; Chatterji, Apratim

2017-02-01

We investigate the efficiency of gelation and network formation in telechelic star polymer melt, where the tips of polymer arms are dipoles while the rest of the monomers are uncharged. Our work is motivated by the experimental observations [A. Kulkarni et al., Macromolecules 48, 6580 (2015)] in which rheological studies of telechelic star polymers of poly-(L-lactide), a bio-degradable polymer, showed a drastic increase in elastic properties (up to 2000 times) compared to corresponding star polymers without the telechelic arm ends. In contrast to previous studies, we avoid using effective attractive Lennard-Jones potentials or dipolar potentials to model telechelic interactions. Instead we use explicit Coulomb positive and negative charges at the tip of polymer-arms of our bead-spring model of star polymers. By our simulations we show that the dipoles at the tip of star arms aggregate together to form clusters of dipoles. Each cluster has contributions from several stars, and in turn each star contributes to several clusters. Thus the entire polymer melt forms a connected network. Network forming tendencies decrease with a decrease of the value of the effective charge constituting the dipole: this can be experimentally realized by choosing a different ionomer for the star tip. We systematically varied the value of dipole charges, the fraction of star-arms with dipoles at the tip, and the length of the arms. The choice of explicit charges in our calculations enables us to make better quantitative predictions about the onset of gelation; moreover we get qualitatively distinct results about structural organization of dipoles within a dipole-cluster.

Network formation and gelation in telechelic star polymers.

PubMed

Wadgaonkar, Indrajit; Chatterji, Apratim

2017-02-28

We investigate the efficiency of gelation and network formation in telechelic star polymer melt, where the tips of polymer arms are dipoles while the rest of the monomers are uncharged. Our work is motivated by the experimental observations [A. Kulkarni et al., Macromolecules 48, 6580 (2015)] in which rheological studies of telechelic star polymers of poly-(L-lactide), a bio-degradable polymer, showed a drastic increase in elastic properties (up to 2000 times) compared to corresponding star polymers without the telechelic arm ends. In contrast to previous studies, we avoid using effective attractive Lennard-Jones potentials or dipolar potentials to model telechelic interactions. Instead we use explicit Coulomb positive and negative charges at the tip of polymer-arms of our bead-spring model of star polymers. By our simulations we show that the dipoles at the tip of star arms aggregate together to form clusters of dipoles. Each cluster has contributions from several stars, and in turn each star contributes to several clusters. Thus the entire polymer melt forms a connected network. Network forming tendencies decrease with a decrease of the value of the effective charge constituting the dipole: this can be experimentally realized by choosing a different ionomer for the star tip. We systematically varied the value of dipole charges, the fraction of star-arms with dipoles at the tip, and the length of the arms. The choice of explicit charges in our calculations enables us to make better quantitative predictions about the onset of gelation; moreover we get qualitatively distinct results about structural organization of dipoles within a dipole-cluster.

The Effect of Temperature on Umami Taste

PubMed Central

Alvarado, Cynthia; Andrew, Kendra; Nachtigal, Danielle

2016-01-01

The effect of temperature on umami taste has not been previously studied in humans. Reported here are 3 experiments in which umami taste was measured for monopotassium glutamate (MPG) and monosodium glutamate (MSG) at solution temperatures between 10 and 37 °C. Experiment 1 showed that for subjects sensitive to MPG on the tongue tip, 1) cooling reduced umami intensity whether sampled with the tongue tip or in the whole mouth, but 2) had no effect on the rate of umami adaptation on the tongue tip. Experiment 2 showed that temperature had similar effects on the umami taste of MSG and MPG on the tongue tip but not in the whole mouth, and that contrary to umami taste, cooling to 10 °C increased rather than decreased the salty taste of both stimuli. Experiment 3 was designed to investigate the contribution of the hT1R1–hT1R3 glutamate receptor to the cooling effect on umami taste by using the T1R3 inhibitor lactisole. However, lactisole failed to block the umami taste of MPG at any temperature, which supports prior evidence that lactisole does not block umami taste for all ligands of the hT1R1–hT1R3 receptor. We conclude that temperature can affect sensitivity to the umami and salty tastes of glutamates, but in opposite directions, and that the magnitude of these effects can vary across stimuli and modes of tasting (i.e., whole mouth vs. tongue tip exposures). PMID:27102813

Critical dynamics in population vaccinating behavior.

PubMed

Pananos, A Demetri; Bury, Thomas M; Wang, Clara; Schonfeld, Justin; Mohanty, Sharada P; Nyhan, Brendan; Salathé, Marcel; Bauch, Chris T

2017-12-26

Vaccine refusal can lead to renewed outbreaks of previously eliminated diseases and even delay global eradication. Vaccinating decisions exemplify a complex, coupled system where vaccinating behavior and disease dynamics influence one another. Such systems often exhibit critical phenomena-special dynamics close to a tipping point leading to a new dynamical regime. For instance, critical slowing down (declining rate of recovery from small perturbations) may emerge as a tipping point is approached. Here, we collected and geocoded tweets about measles-mumps-rubella vaccine and classified their sentiment using machine-learning algorithms. We also extracted data on measles-related Google searches. We find critical slowing down in the data at the level of California and the United States in the years before and after the 2014-2015 Disneyland, California measles outbreak. Critical slowing down starts growing appreciably several years before the Disneyland outbreak as vaccine uptake declines and the population approaches the tipping point. However, due to the adaptive nature of coupled behavior-disease systems, the population responds to the outbreak by moving away from the tipping point, causing "critical speeding up" whereby resilience to perturbations increases. A mathematical model of measles transmission and vaccine sentiment predicts the same qualitative patterns in the neighborhood of a tipping point to greatly reduced vaccine uptake and large epidemics. These results support the hypothesis that population vaccinating behavior near the disease elimination threshold is a critical phenomenon. Developing new analytical tools to detect these patterns in digital social data might help us identify populations at heightened risk of widespread vaccine refusal. Copyright © 2017 the Author(s). Published by PNAS.

Critical dynamics in population vaccinating behavior

PubMed Central

Pananos, A. Demetri; Bury, Thomas M.; Wang, Clara; Schonfeld, Justin; Mohanty, Sharada P.; Nyhan, Brendan; Bauch, Chris T.

2017-01-01

Vaccine refusal can lead to renewed outbreaks of previously eliminated diseases and even delay global eradication. Vaccinating decisions exemplify a complex, coupled system where vaccinating behavior and disease dynamics influence one another. Such systems often exhibit critical phenomena—special dynamics close to a tipping point leading to a new dynamical regime. For instance, critical slowing down (declining rate of recovery from small perturbations) may emerge as a tipping point is approached. Here, we collected and geocoded tweets about measles–mumps–rubella vaccine and classified their sentiment using machine-learning algorithms. We also extracted data on measles-related Google searches. We find critical slowing down in the data at the level of California and the United States in the years before and after the 2014–2015 Disneyland, California measles outbreak. Critical slowing down starts growing appreciably several years before the Disneyland outbreak as vaccine uptake declines and the population approaches the tipping point. However, due to the adaptive nature of coupled behavior–disease systems, the population responds to the outbreak by moving away from the tipping point, causing “critical speeding up” whereby resilience to perturbations increases. A mathematical model of measles transmission and vaccine sentiment predicts the same qualitative patterns in the neighborhood of a tipping point to greatly reduced vaccine uptake and large epidemics. These results support the hypothesis that population vaccinating behavior near the disease elimination threshold is a critical phenomenon. Developing new analytical tools to detect these patterns in digital social data might help us identify populations at heightened risk of widespread vaccine refusal. PMID:29229821

Direct observation of the actin filament by tip-scan atomic force microscopy

PubMed Central

Narita, Akihiro; Usukura, Eiji; Yagi, Akira; Tateyama, Kiyohiko; Akizuki, Shogo; Kikumoto, Mahito; Matsumoto, Tomoharu; Maéda, Yuichiro; Ito, Shuichi; Usukura, Jiro

2016-01-01

Actin filaments, the actin–myosin complex and the actin–tropomyosin complex were observed by a tip-scan atomic force microscope (AFM), which was recently developed by Olympus as the AFM part of a correlative microscope. This newly developed AFM uses cantilevers of similar size as stage-scan AFMs to improve substantially the spatial and temporal resolution. Such an approach has previously never been possible by a tip-scan system, in which a cantilever moves in the x, y and z directions. We evaluated the performance of this developed tip-scan AFM by observing the molecular structure of actin filaments and the actin–tropomyosin complex. In the image of the actin filament, the molecular interval of the actin subunits (∼5.5 nm) was clearly observed as stripes. From the shape of the stripes, the polarity of the actin filament was directly determined and the results were consistent with the polarity determined by myosin binding. In the image of the actin–tropomyosin complex, each tropomyosin molecule (∼2 nm in diameter) on the actin filament was directly observed without averaging images of different molecules. Each tropomyosin molecule on the actin filament has never been directly observed by AFM or electron microscopy. Thus, our developed tip-scan AFM offers significant potential in observing purified proteins and cellular structures at nanometer resolution. Current results represent an important step in the development of a new correlative microscope to observe nm-order structures at an acceptable frame rate (∼10 s/frame) by AFM at the position indicated by the fluorescent dye observed under a light microscope. PMID:27242058

Turing mechanism underlying a branching model for lung morphogenesis.

PubMed

Xu, Hui; Sun, Mingzhu; Zhao, Xin

2017-01-01

The mammalian lung develops through branching morphogenesis. Two primary forms of branching, which occur in order, in the lung have been identified: tip bifurcation and side branching. However, the mechanisms of lung branching morphogenesis remain to be explored. In our previous study, a biological mechanism was presented for lung branching pattern formation through a branching model. Here, we provide a mathematical mechanism underlying the branching patterns. By decoupling the branching model, we demonstrated the existence of Turing instability. We performed Turing instability analysis to reveal the mathematical mechanism of the branching patterns. Our simulation results show that the Turing patterns underlying the branching patterns are spot patterns that exhibit high local morphogen concentration. The high local morphogen concentration induces the growth of branching. Furthermore, we found that the sparse spot patterns underlie the tip bifurcation patterns, while the dense spot patterns underlies the side branching patterns. The dispersion relation analysis shows that the Turing wavelength affects the branching structure. As the wavelength decreases, the spot patterns change from sparse to dense, the rate of tip bifurcation decreases and side branching eventually occurs instead. In the process of transformation, there may exists hybrid branching that mixes tip bifurcation and side branching. Since experimental studies have reported that branching mode switching from side branching to tip bifurcation in the lung is under genetic control, our simulation results suggest that genes control the switch of the branching mode by regulating the Turing wavelength. Our results provide a novel insight into and understanding of the formation of branching patterns in the lung and other biological systems.

Unveiling Singlet Fission Mediating States in TIPS-pentacene and its Aza Derivatives.

PubMed

Herz, Julia; Buckup, Tiago; Paulus, Fabian; Engelhart, Jens U; Bunz, Uwe H F; Motzkus, Marcus

2015-06-25

Femtosecond pump-depletion-probe experiments were carried out in order to shed light on the ultrafast excited-state dynamics of triisopropylsilylethynyl (TIPS)-pentacene and two nitrogen-containing derivatives, namely, diaza-TIPS-pentacene and tetraaza-TIPS-pentacene. Measurements performed in the visible and near-infrared spectral range in combination with rate model simulations reveal that singlet fission proceeds via the extremely short-lived intermediate (1)TT state, which absorbs in the near-infrared spectral region only. The T1 → T3 transition probed in the visible region shows a rise time that comprises two components according to a consecutive reaction (S1 → (1)TT → T1). The incorporation of nitrogen atoms into the acene structure leads to shorter dynamics, but the overall triplet formation follows the same kinetic model. This is of particular importance, since experiments on tetraaza-TIPS-pentacene allow for investigation of the triplet state in the visible range without an overlapping singlet contribution. In addition, the pump-depletion-probe experiments show that the triplet absorption in the visible (T1 → T3) and near-infrared (T1 → T2) regions occurs from the same initial state, which was questioned in previous studies. Furthermore, an additional ultrafast transfer between the excited triplet states (T3 → T2) is identified, which is also in agreement with the rate model simulation. By applying depletion pulses, which are resonant with higher vibrational levels, we gain insight into internal vibrational energy redistribution processes within the triplet manifold. This additional information is of great relevance regarding the study of loss channels within these materials.

A New Method for Determining Hamaker Constants of Solids Based on the Dynamic Approach Behavior of an Atomic Force Microscope

NASA Astrophysics Data System (ADS)

Fronczak, Sean G.

The Hamaker constant, A, is a quantitative measure of the fundamental attractive van der Waals (vdW) interaction for microscale and nanoscale materials. This parameter captures each material's compositional effects on the vdW force, which is often needed as input for predicting the vdW interactions between particles and surfaces. Experimental attempts to determine A using an atomic force microscope (AFM) are typically hindered by issues inherent to the cantilever-tip-surface contact regime, such as surface roughness and deformation, and contact separation distance. Thus, we developed a new method for estimating Hamaker constants from the non-contact approach regime of an AFM experiment (Fronczak et al., 2017, Langmuir 33, 714-725). This method invokes a quasi-dynamic description of the cantilever tip's approach to contact, in which the inertial effects of the tip motion are accounted for when analyzing the trajectory of the tip's approach towards the substrate. The method was tested experimentally using silica, alumina and polystyrene substrates, and was demonstrated to yield estimates of A for these materials that were in very good agreement with previously published Lifshitz calculations. As with various other approaches to determining A, our new method relies heavily on the accuracy of the geometric model used to predict the interaction between the AFM tip and the substrate. For the initial validation experiments of our new method, we therefore focused on describing the shape of the cantilever tip as closely as possible, utilizing a complex model of a truncated pyramid with a spherical cap. Although this pyramidal geometry can be confirmed and the dimensions estimated via scanning electron microscopy (SEM), even high-resolution SEM images of the tip cannot provide sufficient detail to allow precise enough determination of the tip's geometric parameters. Consequently, we also propose an adaptation of the method, in which these difficult to quantify geometric effects are still fully captured via the convenient description of the tip as an 'effective' perfect sphere. Hence, the geometric complexity of the cantilever tip is no longer explicitly required for the determination of A. First, a tip is 'calibrated', whereby the deflection at first contact between the cantilever tip and a smooth surface of known vdW properties is determined and an effective radius, Reff, of the tip is calculated. The tip's approach to contact toward other similarly smooth surfaces can then be well-described by using only this single geometric parameter. We demonstrate the practicality and accuracy of this updated method by comparing the results with both the original pyramid model and Lifshitz approximations (when available) for flat substrates composed of silica, polystyrene, highly ordered pyrolytic graphite (HOPG), sapphire (alpha-Al3O2), Plexiglas (PMMA), and acrylonitrile butadiene styrene (ABS). Then, the modified quasi-dynamic model was employed to study the strength of the adhesive interaction between TNT and several swab materials which are used as explosive detection devices at security checkpoints. This information is crucial for the development and improvement of next-generation swab detection protocols to further advance this field. Finally, we also include the effects of thermal noise into our quasi-dynamic description of the cantilever motion to better understand how such noise might influence the accuracy of our method. We likewise determine, for the first time, the effects of instrument noise on the accuracy of other approach-to-contact methodologies for determining A.

Modern mammal origins: evolutionary grades in the Early Cretaceous of North America.

PubMed

Jacobs, L L; Winkler, D A; Murry, P A

1989-07-01

Major groups of modern mammals have their origins in the Mesozoic Era, yet the mammalian fossil record is generally poor for that time interval. Fundamental morphological changes that led to modern mammals are often represented by small samples of isolated teeth. Fortunately, functional wear facets on teeth allow prediction of the morphology of occluding teeth that may be unrepresented by fossils. A major step in mammalian evolution occurred in the Early Cretaceous with the evolution of tribosphenic molars, which characterize marsupials and placentals, the two most abundant and diverse extant groups of mammals. A tooth from the Early Cretaceous (110 million years before present) of Texas tests previous predictions (based on lower molars) of the morphology of upper molars in early tribosphenic dentitions. The lingual cusp (protocone) is primitively without shear facets, as expected, but the cheek side of the tooth is derived (advanced) in having distinctive cusps along the margin. The tooth, although distressingly inadequate to define many features of the organism, demonstrates unexpected morphological diversity at a strategic stage of mammalian evolution and falsifies previous claims of the earliest occurrence of true marsupials.

Regulation of Cortical Dynamic Range by Background Synaptic Noise and Feedforward Inhibition.

PubMed

Khubieh, Ayah; Ratté, Stéphanie; Lankarany, Milad; Prescott, Steven A

2016-08-01

The cortex encodes a broad range of inputs. This breadth of operation requires sensitivity to weak inputs yet non-saturating responses to strong inputs. If individual pyramidal neurons were to have a narrow dynamic range, as previously claimed, then staggered all-or-none recruitment of those neurons would be necessary for the population to achieve a broad dynamic range. Contrary to this explanation, we show here through dynamic clamp experiments in vitro and computer simulations that pyramidal neurons have a broad dynamic range under the noisy conditions that exist in the intact brain due to background synaptic input. Feedforward inhibition capitalizes on those noise effects to control neuronal gain and thereby regulates the population dynamic range. Importantly, noise allows neurons to be recruited gradually and occludes the staggered recruitment previously attributed to heterogeneous excitation. Feedforward inhibition protects spike timing against the disruptive effects of noise, meaning noise can enable the gain control required for rate coding without compromising the precise spike timing required for temporal coding. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Site-directed mutagenesis of Autographa californica nucleopolyhedrovirus (AcNPV) polyhedrin: effect on polyhedron structure.

PubMed

Bravo-Patiño, A; Ibarra, J E

2000-01-01

Amino acids Lys34, His36, and Phe37 were substituted by PCR-mediated, site-directed mutagenesis for three Trp's in the AcNPV polyhedrin sequence. Phase contrast microscopy revealed refringent, amorphous polyhedra in the nuclei of infected cells. Electron microscopy confirmed a great variation in form and size of the mutated polyhedra. Although crystallization of the mutated polyhedrin occurred, it was irregular within each polyhedron. Virion occlusion was also severely affected. Virions were partially occluded, or only one virion was occluded per polyhedron. Results suggest that the substitution of these three amino acids affected the morphology of polyhedra, the uniformity of crystallization within each polyhedron, and the virion occlusion.

Changes in the proteomic and metabolic profiles of Beta vulgaris root tips in response to iron deficiency and resupply

PubMed Central

2010-01-01

Background Plants grown under iron deficiency show different morphological, biochemical and physiological changes. These changes include, among others, the elicitation of different strategies to improve the acquisition of Fe from the rhizosphere, the adjustment of Fe homeostasis processes and a reorganization of carbohydrate metabolism. The application of modern techniques that allow the simultaneous and untargeted analysis of multiple proteins and metabolites can provide insight into multiple processes taking place in plants under Fe deficiency. The objective of this study was to characterize the changes induced in the root tip proteome and metabolome of sugar beet plants in response to Fe deficiency and resupply. Results Root tip extract proteome maps were obtained by 2-D isoelectric focusing polyacrylamide gel electrophoresis, and approximately 140 spots were detected. Iron deficiency resulted in changes in the relative amounts of 61 polypeptides, and 22 of them were identified by mass spectrometry (MS). Metabolites in root tip extracts were analyzed by gas chromatography-MS, and more than 300 metabolites were resolved. Out of 77 identified metabolites, 26 changed significantly with Fe deficiency. Iron deficiency induced increases in the relative amounts of proteins and metabolites associated to glycolysis, tri-carboxylic acid cycle and anaerobic respiration, confirming previous studies. Furthermore, a protein not present in Fe-sufficient roots, dimethyl-8-ribityllumazine (DMRL) synthase, was present in high amounts in root tips from Fe-deficient sugar beet plants and gene transcript levels were higher in Fe-deficient root tips. Also, a marked increase in the relative amounts of the raffinose family of oligosaccharides (RFOs) was observed in Fe-deficient plants, and a further increase in these compounds occurred upon short term Fe resupply. Conclusions The increases in DMRL synthase and in RFO sugars were the major changes induced by Fe deficiency and resupply in root tips of sugar beet plants. Flavin synthesis could be involved in Fe uptake, whereas RFO sugars could be involved in the alleviation of oxidative stress, C trafficking or cell signalling. Our data also confirm the increase in proteins and metabolites related to carbohydrate metabolism and TCA cycle pathways. PMID:20565974

Essays in Applied Microeconomics

NASA Astrophysics Data System (ADS)

Ge, Qi

This dissertation consists of three self-contained applied microeconomics essays on topics related to behavioral economics and industrial organization. Chapter 1 studies how sentiment as a result of sports event outcomes affects consumers' tipping behavior in the presence of social norms. I formulate a model of tipping behavior that captures consumer sentiment following a reference-dependent preference framework and empirically test its relevance using the game outcomes of the NBA and the trip and tipping data on New York City taxicabs. While I find that consumers' tipping behavior responds to unexpected wins and losses of their home team, particularly in close game outcomes, I do not find evidence for loss aversion. Coupled with the findings on default tipping, my empirical results on the asymmetric tipping responses suggest that while social norms may dominate loss aversion, affect and surprises can result in freedom on the upside of tipping. Chapter 2 utilizes a novel data source of airline entry and exit announcements and examines how the incumbent airlines adjust quality provisions as a response to their competitors' announcements and the role of timing in such responses. I find no evidence that the incumbents engage in preemptive actions when facing probable entry and exit threats as signaled by the competitors' announcements in either short term or long term. There is, however, evidence supporting their responses to the competitors' realized entry or exit. My empirical findings underscore the role of timing in determining preemptive actions and suggest that previous studies may have overestimated how the incumbent airlines respond to entry threats. Chapter 3, which is collaborated with Benjamin Ho, investigates the habit formation of consumers' thermostat setting behavior, an often implicitly made decision and yet a key determinant of home energy consumption and expenditures. We utilize a high frequency dataset on household thermostat usage and find that while thermostat usage exhibits strong persistence in habits, consumers do respond to salient outdoor temperature shocks and the underlying heterogeneity in preferences can help explain much of the variation in responses. Our findings have direct policy implications on how conservation policies impact energy use.

An effective technique to facilitate radiographic stone visualization with an internal stent during shock wave lithotripsy.

PubMed

Sundaram, C P; Saltzman, B

1998-10-01

We describe a simple method to assist stone localization during shock wave lithotripsy in the presence of a Double J stent. A 4F whistle tip ureteral catheter is passed alongside a previously inserted 6F Double J stent. The tip of the ureteral stent is positioned in the lower or mid third of the ureter. Contrast material is injected through the ureteral catheter during lithotripsy to assist stone localization. This technique has been successful in localization of poorly opacified renal stones during lithotripsy. Radiolucent and poorly calcified renal stones can be easily localized during shock wave lithotripsy, despite the presence of a Double J stent. No special catheters or stents are required for this technique.

Effect of thrombus composition and viscosity on sonoreperfusion efficacy in a model of microvascular obstruction

PubMed Central

Black, John J.; Yu, Francois T. H.; Schnatz, Rick G.; Flordeliza, Xucai Chen; Villanueva, S.; Pacella, John J.

2016-01-01

Distal embolization of microthrombi during stenting for myocardial infarction (MI) causes microvascular obstruction (MVO). We have previously shown that sonoreperfusion (SRP), a microbubble (MB)-mediated ultrasonic (US) therapy, resolves MVO from venous microthrombi in vitro in saline. However, blood is more viscous than saline and arterial thrombi that embolize during stenting are mechanically distinct from venous clot. Therefore, we tested the hypothesis that MVO created with arterial microthrombi are more resistant to SRP therapy compared with venous microthrombi and higher viscosity further increases the US requirement for effective SRP in an in vitro model of MVO. Lipid MB suspended in plasma with adjusted viscosity (1.1 or 4.0 cP) were passed through tubing bearing a mesh with 40 μm pores to simulate a microvascular cross-section; upstream pressure reflected thrombus burden. To simulate MVO, the mesh was occluded with either arterial or venous microthrombi to increase upstream pressure to 40±5 mmHg. Therapeutic long-tone-burst US was delivered to the occluded area for 20 min. MB activity was recorded with a passive cavitation detector (PCD). MVO caused by arterial microthrombi at either blood or plasma viscosity resulted in less effective SRP therapy, compared to venous thrombi. Higher viscosity further reduced the effectiveness of SRP therapy. PCD showed a decrease in inertial cavitation when viscosity was increased while stable cavitation was affected in a more complex manner. Overall, these data suggest that arterial thrombi may require higher acoustic pressure US than venous thrombi to achieve similar SRP efficacy, increased viscosity decreases SRP efficacy, and both inertial and stable cavitation are implicated in observed SRP efficacy. PMID:27207018

A long baseline global stereo matching based upon short baseline estimation

NASA Astrophysics Data System (ADS)

Li, Jing; Zhao, Hong; Li, Zigang; Gu, Feifei; Zhao, Zixin; Ma, Yueyang; Fang, Meiqi

2018-05-01

In global stereo vision, balancing the matching efficiency and computing accuracy seems to be impossible because they contradict each other. In the case of a long baseline, this contradiction becomes more prominent. In order to solve this difficult problem, this paper proposes a novel idea to improve both the efficiency and accuracy in global stereo matching for a long baseline. In this way, the reference images located between the long baseline image pairs are firstly chosen to form the new image pairs with short baselines. The relationship between the disparities of pixels in the image pairs with different baselines is revealed by considering the quantized error so that the disparity search range under the long baseline can be reduced by guidance of the short baseline to gain matching efficiency. Then, the novel idea is integrated into the graph cuts (GCs) to form a multi-step GC algorithm based on the short baseline estimation, by which the disparity map under the long baseline can be calculated iteratively on the basis of the previous matching. Furthermore, the image information from the pixels that are non-occluded under the short baseline but are occluded for the long baseline can be employed to improve the matching accuracy. Although the time complexity of the proposed method depends on the locations of the chosen reference images, it is usually much lower for a long baseline stereo matching than when using the traditional GC algorithm. Finally, the validity of the proposed method is examined by experiments based on benchmark datasets. The results show that the proposed method is superior to the traditional GC method in terms of efficiency and accuracy, and thus it is suitable for long baseline stereo matching.

The TonB-dependent Transporter FhuA in Planar Lipid Bilayers: partial exit of its plug from the barrel

PubMed Central

Udho, Eshwar; Jakes, Karen S.; Finkelstein, Alan

2012-01-01

TonB-dependent transporters (TBDTs), which transport iron-chelating siderophores and vitamin B12 across the outer membrane of gram negative bacteria, share a conserved architecture of a 22-stranded beta-barrel with an amino-terminal plug domain occluding the barrel. We previously reported that we could induce TBDTs to reversibly open in planar lipid bilayers via the use of urea and that these channels were responsive to physiological concentrations of ligands. Here we report that in the presence of urea, trypsin can cleave the amino-terminal 67 residues of the plug of the TonB-dependent transporter FhuA, as assessed by gel shift and mass spectrometry assays. On the bilayer, trypsin treatment in the presence of urea resulted in the induced conductance no longer being reversed upon removal of urea, suggesting that urea opens intact FhuA channels by pulling the plug at least partly out of the barrel, and that removal of the urea then allows reinsertion of the plug into the barrel. When expressed separately, the FhuA plug domain was found to be a mostly unfolded structure that was able to occlude isolated FhuA beta-barrels inserted into the membrane. Thus, although folded in the barrel, the plug need not be folded upon exiting the barrel. The rate of insertion of the beta-barrels into the membrane was tremendously increased in the presence of an osmotic gradient provided by either urea or glycerol. Negative staining electron microscopy showed that FhuA in a detergent solution formed vesicles, thus explaining why an osmotic gradient promoted the insertion of FhuA into membranes. PMID:22846061

The influence of non-planar geometry on the flow within a distal end-to-side anastomosis

NASA Astrophysics Data System (ADS)

Sherwin, S. J.; Doorly, D. J.; Peiro, J.; Caro, C. G.

1998-11-01

The pattern of the flow in arteries is strongly influenced by the three-dimensional shape of the geometry. Curvature and torsion of the wall geometry alters the axial velocity distribution, and introduces cross flow velocity components. In this investigation we have considered flow in a model geometry of a fully occluded 45^o distal end-to-side anastomosis. Previous investigations have typically focused on planar end-to-side anastomoses where the bypass and host vessels have a plane of symmetry. We have increased the complexity of the model by considering a non-planar geometry produced by deforming the bypass vessel out of the plane of symmetry. The flows have been numerically and experimentally investigated using a spectral/hp element algorithm and magnetic resonance imaging. The significant effect of the non-planar geometry is to introduce a bulk rotation of the two secondary flow cells present in flow within a planar geometry. A reduction in wall shear stress is observed at the bed of the anastomosis and a larger absolute flux of velocity is seen within the occluded region proximal to the anastomosis. Current investigations have considered the role of pulsatility in the form of a non-reversing sinusoidal oscillation. In this case a separation bubble, not present in the steady case, is seen at the toe of the anastomosis during the systolic part of the cycle. The role of geometry and pulsatility on particle motion has also been addressed with a view to determining the shear exposure on particle within these types of flows.

Balloon-augmented Onyx endovascular ligation: initial human experience and comparison with coil ligation.

PubMed

Osanai, Toshiya; Bain, Mark D; Toth, Gabor; Hussain, M Shazam; Hui, Ferdinand K

2015-08-01

Carotid artery sacrifice remains an important procedure for cerebral vascular disorders despite the development of new endovascular devices. Conventional carotid artery sacrifice with detachable coils alone often requires numerous coils to complete occlusion. To describe the initial human experience with balloon-augmented Onyx and coil vessel sacrifice based on our previous experience with animals. We performed a retrospective review of patients who underwent carotid artery sacrifice between 2008 and 2012 in accordance with local investigational review board approval. Two methods were used to occlude carotid arteries-namely, combined Onyx and coil embolization and traditional coil embolization. We compared the two methods for the cost of embolizate, time to occlude the vessels, and the number of coils. Eight consecutive patients (combined group n=3, traditional group n=5) were assessed. The median cost of embolic material was $6321 in the combined Onyx and coil embolization group and $29 996 in the traditional coil embolization group. The median time from first coil placement to achievement of vessel occlusion was 52 min in the Onyx group and 113 min in the coil embolization group. The median number of coils used was 4 in the Onyx group and 35 in the coil embolization group (p<0.05). No symptomatic complications or recurrences were seen in the combined group. Balloon-augmented Onyx endovascular ligation may reduce costs and fluoroscopy times during vessel sacrifice. Further studies in a larger number of patients are needed to confirm these findings. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.