CO2 Push-Pull Dual (Conjugate) Faults Injection Simulations

DOE Data Explorer

Oldenburg, Curtis (ORCID:0000000201326016); Lee, Kyung Jae; Doughty, Christine; Jung, Yoojin; Borgia, Andrea; Pan, Lehua; Zhang, Rui; Daley, Thomas M.; Altundas, Bilgin; Chugunov, Nikita

2017-07-20

This submission contains datasets and a final manuscript associated with a project simulating carbon dioxide push-pull into a conjugate fault system modeled after Dixie Valley- sensitivity analysis of significant parameters and uncertainty prediction by data-worth analysis. Datasets include: (1) Forward simulation runs of standard cases (push & pull phases), (2) Local sensitivity analyses (push & pull phases), and (3) Data-worth analysis (push & pull phases).

Foot placement strategy in pushing and pulling.

PubMed

Lee, Tzu-Hsien

2018-01-01

Pushing and pulling tasks are very common in daily and industrial workplaces. They are one major source of musculoskeletal complaints. This study aimed to examine the foot placement strategy while pushing and pulling. Thirteen young males and ten young females were recruited as participants. A two (pushing and pulling) by four (48 cm, 84 cm, 120 cm, and 156 cm) factorial design was used. Exertion direction and exertion height significantly affected foot placement strategy. Pushing task needed more anteroposterior space than pulling task. The percentages of female/male for trailing foot position ranged from 77% to 90% (pushing) and from 80% to 93% (pulling) across the exertion heights. Practitioners should provide an anteroposterior space approximately to 70% body stature for workers to exert their maximum pulling and pushing strengths.

Dynamic push-pull characteristics at three hand-reach envelopes: applications for the workplace.

PubMed

Calé-Benzoor, Maya; Dickstein, Ruth; Arnon, Michal; Ayalon, Moshe

2016-01-01

Pushing and pulling are common tasks in the workplace. Overexertion injuries related to manual pushing and pulling are often observed, and therefore the understanding of work capacity is important for efficient and safe workstation design. The purpose of the present study was to describe workloads obtained during different reach envelopes during a seated push-pull task. Forty-five women performed an isokinetic push-pull sequence at two velocities. Strength, work and agonist/antagonist muscle ratio were calculated for the full range of motion (ROM). We then divided the ROM into three reach envelopes - neutral, medium, and maximum reach. The work capacity for each direction was determined and the reach envelope work data were compared. Push capability was best at medium reach envelope and pulling was best at maximum reach envelope. Push/pull strength ratio was approximately 1. A recommendation was made to avoid strenuous push-pull tasks at neutral reach envelopes. Copyright © 2015 Elsevier Ltd and The Ergonomics Society. All rights reserved.

Laboratory evaluation techniques to investigate the spatial potential of repellents for push & pull mosquito control systems

USDA-ARS?s Scientific Manuscript database

A protocol has been developed for the indoor evaluation of candidate spatial repellents intended for use in push and pull systems. Single treatments (catnip oil, 1-methylpiperazine and homopiperazine) and a mixture of catnip oil and homopiperazine were tested with yellow-fever mosquitoes (Aedes aegy...

Enhanced Basicity of Push-Pull Nitrogen Bases in the Gas Phase.

PubMed

Raczyńska, Ewa D; Gal, Jean-François; Maria, Pierre-Charles

2016-11-23

Nitrogen bases containing one or more pushing amino-group(s) directly linked to a pulling cyano, imino, or phosphoimino group, as well as those in which the pushing and pulling moieties are separated by a conjugated spacer (C═X) n , where X is CH or N, display an exceptionally strong basicity. The n-π conjugation between the pushing and pulling groups in such systems lowers the basicity of the pushing amino-group(s) and increases the basicity of the pulling cyano, imino, or phosphoimino group. In the gas phase, most of the so-called push-pull nitrogen bases exhibit a very high basicity. This paper presents an analysis of the exceptional gas-phase basicity, mostly in terms of experimental data, in relation with structure and conjugation of various subfamilies of push-pull nitrogen bases: nitriles, azoles, azines, amidines, guanidines, vinamidines, biguanides, and phosphazenes. The strong basicity of biomolecules containing a push-pull nitrogen substructure, such as bioamines, amino acids, and peptides containing push-pull side chains, nucleobases, and their nucleosides and nucleotides, is also analyzed. Progress and perspectives of experimental determinations of GBs and PAs of highly basic compounds, termed as "superbases", are presented and benchmarked on the basis of theoretical calculations on existing or hypothetical molecules.

New devices for measuring forces on the kayak foot bar and on the seat during flat-water kayak paddling: a technical report.

PubMed

Nilsson, Johnny E; Rosdahl, Hans G

2014-03-01

The purpose was to develop and validate portable force-measurement devices for recording push and pull forces applied by each foot to the foot bar of a kayak and the horizontal force at the seat. A foot plate on a single-point force transducer mounted on the kayak foot bar underneath each foot allowed the push and pull forces to be recorded. Two metal frames interconnected with 4 linear ball bearings, and a force transducer allowed recording of horizontal seat force. The foot-bar-force device was calibrated by loading each foot plate with weights in the push-pull direction perpendicular to the foot plate surface, while the seat-force device was calibrated to horizontal forces with and without weights on the seat. A strong linearity (r2 = .99-1.0) was found between transducer output signal and load force in the push and pull directions for both foot-bar transducers perpendicular to the foot plate and the seat-force-measuring device. Reliability of both devices was tested by means of a test-retest design. The coefficient of variation (CV) for foot-bar push and pull forces ranged from 0.1% to 1.1%, and the CV for the seat forces varied from 0.6% to 2.2%. The current study opens up a field for new investigations of the forces generated in the kayak and ways to optimize kayak-paddling performance.

Low temperature-pressure batch experiments and field push-pull tests: Assessing potential effects of an unintended CO2 release from CCUS projects on groundwater chemistry

NASA Astrophysics Data System (ADS)

Mickler, P. J.; Yang, C.; Lu, J.; Reedy, R. C.; Scanlon, B. R.

2012-12-01

Carbon Capture Utilization and Storage projects (CCUS), where CO2 is captured at point sources such as power stations and compressed into a supercritical liquid for underground storage, has been proposed to reduce atmospheric CO2 and mitigate global climate change. Problems may arise from CO2 releases along discreet pathways such as abandoned wells and faults, upwards and into near surface groundwater. Migrating CO2 may inversely impact fresh water resources by increasing mineral solubility and dissolution rates and mobilizing harmful trace elements including As and Pb. This study addresses the impacts on fresh water resources through a combination of laboratory batch experiments, where aquifer sediment are reacted in their corresponding groundwater in 100% CO2 environments, and field push-pull tests where groundwater is equilibrated with 100% CO2, reacted in-situ in the groundwater system, and pulled out for analyses. Batch experiments were performed on aquifer material from carbonate dominated, mixed carbonate/silicalstic, and siliclastic dominated systems. A mixed silicalstic/carbonate system was chosen for the field based push-pull test. Batch experiment results suggest carbonate dissolution increased the concentration of Ca, Mg, Sr, Ba, Mn, U and HCO3- in groundwater. In systems with significant carbonate content, dissolution continued until carbonate saturation was achieved at approximately 1000 hr. Silicate dissolution increased the conc. of Si, K Ni and Co, but at much lower rates than carbonate dissolution. The elements As, Mo, V, Zn, Se and Cd generally show similar behavior where concentrations initially increase but soon drop to levels at or below the background concentrations (~48 hours). A Push-Pull test on one aquifer system produced similar geochemical behavior but observed reaction rates are higher in batch experiments relative to push-pull tests. Release of CO2 from CCUS sites into overlying aquifer systems may adversely impact groundwater quality primarily through carbonate dissolution which releases Ca and elements that substitute for Ca in crystal lattices. Silicate weathering releases primarily Si and K at lower rates. Chemical changes with the addition of CO2 may initially mobilize As, Mo, V, Zn, Se and Cd but these elements become immobile in the lowered pH water and sorb onto aquifer minerals. A combined laboratory batch experiment and field push-pull test in fresh water aquifers overlying CCUS projects will best characterize the response of the aquifer to increased pCO2. The long experimental duration of the batch experiments may allow reactions to reach equilibrium however; reaction rates may be artificially high due to increased mineral surface areas. Field based push-pull tests offer a more realistic water rock ratio and test a much larger volume of aquifer material but the test must be shorter in duration because the high pCO2 water is subject to mixing with low pCO2 background water and migration away from the test well with groundwater flow. A comparison of the two methods best characterizes the potential effects on groundwater chemistry

Large-Scale CTRW Analysis of Push-Pull Tracer Tests and Other Transport in Heterogeneous Porous Media

NASA Astrophysics Data System (ADS)

Hansen, S. K.; Berkowitz, B.

2014-12-01

Recently, we developed an alternative CTRW formulation which uses a "latching" upscaling scheme to rigorously map continuous or fine-scale stochastic solute motion onto discrete transitions on an arbitrarily coarse lattice (with spacing potentially on the meter scale or more). This approach enables model simplification, among many other things. Under advection, for example, we see that many relevant anomalous transport problems may be mapped into 1D, with latching to a sequence of successive, uniformly spaced planes. On this formulation (which we term RP-CTRW), the spatial transition vector may generally be made deterministic, with CTRW waiting time distributions encapsulating all the stochastic behavior. We demonstrate the excellent performance of this technique alongside Pareto-distributed waiting times in explaining experiments across a variety of scales using only two degrees of freedom. An interesting new application of the RP-CTRW technique is the analysis of radial (push-pull) tracer tests. Given modern computational power, random walk simulations are a natural fit for the inverse problem of inferring subsurface parameters from push-pull test data, and we propose them as an alternative to the classical type curve approach. In particular, we explore the visibility of heterogeneity through non-Fickian behavior in push-pull tests, and illustrate the ability of a radial RP-CTRW technique to encapsulate this behavior using a sparse parameterization which has predictive value.

Mechanical load on the low back and shoulders during pushing and pulling of two-wheeled waste containers compared with lifting and carrying of bags and bins.

PubMed

Schibye, B; Søgaard, K; Martinsen, D; Klausen, K

2001-08-01

Compare the mechanical load on the low back and shoulders during pushing and pulling a two-wheeled container with the load during lifting and carrying the same amount of waste. Only little is known about risk factors and mechanical loads during push/pull operations. A complete 2(3) factor push/pull experiment. A two-wheeled container with 25 or 50 kg was pushed in front of and pulled behind the body by seven waste collectors. Further, the same subjects lifted and carried a paper bag and a dustbin both loaded with 7 and 25 kg. All operations were video recorded and the push/pull force was measured by means of a three-dimensional force transducer. Peak Motus and Watbak software were used for digitising and calculation of torque at L4/L5 and the shoulder joints and compression and shear forces at L4/L5. During pushing and pulling the compression at L4/L5 is from 605 to 1445 N. The extension torque at L4/L5 produced by the push/pull force is counteracted by the forward leaning of the upper body. The shear force is below 202 N in all situations. The torque at the shoulders is between 1 and 38 Nm. In the present experiments the torques at the low back and the shoulders are low during pushing and pulling. No relation exists between the size of the external force and the torque at the low back and the shoulder. Pushing and pulling are common in many workplaces and have often replaced lifting and carrying situations. This has emphasised the need for more knowledge of the internal mechanical load on the body during these activities.

Design of a haptic device with grasp and push-pull force feedback for a master-slave surgical robot.

PubMed

Hu, Zhenkai; Yoon, Chae-Hyun; Park, Samuel Byeongjun; Jo, Yung-Ho

2016-07-01

We propose a portable haptic device providing grasp (kinesthetic) and push-pull (cutaneous) sensations for optical-motion-capture master interfaces. Although optical-motion-capture master interfaces for surgical robot systems can overcome the stiffness, friction, and coupling problems of mechanical master interfaces, it is difficult to add haptic feedback to an optical-motion-capture master interface without constraining the free motion of the operator's hands. Therefore, we utilized a Bowden cable-driven mechanism to provide the grasp and push-pull sensation while retaining the free hand motion of the optical-motion capture master interface. To evaluate the haptic device, we construct a 2-DOF force sensing/force feedback system. We compare the sensed force and the reproduced force of the haptic device. Finally, a needle insertion test was done to evaluate the performance of the haptic interface in the master-slave system. The results demonstrate that both the grasp force feedback and the push-pull force feedback provided by the haptic interface closely matched with the sensed forces of the slave robot. We successfully apply our haptic interface in the optical-motion-capture master-slave system. The results of the needle insertion test showed that our haptic feedback can provide more safety than merely visual observation. We develop a suitable haptic device to produce both kinesthetic grasp force feedback and cutaneous push-pull force feedback. Our future research will include further objective performance evaluations of the optical-motion-capture master-slave robot system with our haptic interface in surgical scenarios.

Design of push-pull system to control diesel particular matter inside a dead-end entry.

PubMed

Zheng, Yi; Thiruvengadam, Magesh; Lan, Hai; Tien, Jerry C

Diesel particulate matter (DPM) is considered to be carcinogenic after prolonged exposure. With more diesel-powered equipment used in underground mines, miners' exposure to DPM has become an increasing concern. This paper used computational fluid dynamics method to study the DPM dispersion in a dead-end entry with loading operation. The effects of different push-pull ventilation systems on DPM distribution were evaluated to improve the working conditions for underground miners. The four push-pull systems considered include: long push and short pull tubing; short push and long pull tubing, long push and curved pull tubing, and short push and curved pull tubing. A species transport model with buoyancy effect was used to examine the DPM dispersion pattern with unsteady state analysis. During the 200 s of loading operation, high DPM levels were identified in the face and dead-end entry regions. This study can be used for mining engineer as guidance to design and setup local ventilation, select DPM control strategies and for DPM annual training for underground miners.

Pushing, pulling and manoeuvring an industrial cart: a psychophysiological study.

PubMed

Giagloglou, Evanthia; Radenkovic, Milan; Brankovic, Sasa; Antoniou, Panagiotis; Zivanovic-Macuzic, Ivana

2017-09-18

One of the most frequent manual occupational tasks involves the pushing and pulling of a cart. Although several studies have associated health risks with pushing and pulling, the effects are not clear since occupational tasks have social, cognitive and physical components. The present work investigates a real case of a pushing and pulling occupational task from a manufacturing company. The study initially characterizes the case in accordance with Standard No. ISO 11228-2:2007 as low risk. An experiment with 14 individuals during three modalities of pushing and pulling was performed in order to further investigate the task with the application of electrophysiology. At the end, a simple questionnaire was given. The results show electrophysiological differences among the three modalities of pushing and pulling, with a major difference between action with no load and fully loaded with a full range of motions on the cart to handle.

On the Push-Pull Mobile Learning of Electric Welding

ERIC Educational Resources Information Center

Chung, Chih-Chao; Dzan, Wei-Yuan; Cheng, Yuh-Ming; Lou, Shi-Jer

2017-01-01

This study aims to explore the learning effects and attitudes of students in the course electric welding practice in a university of science and technology to which the push-pull technology-based mobile learning system is applied. In this study, the push-pull technology is adopted to establish a mobile learning system and develop the Push-pull…

Field demonstration of CO2 leakage detection and potential impacts on groundwater quality at Brackenridge Field Laboratory

NASA Astrophysics Data System (ADS)

Zou, Y.; Yang, C.; Guzman, N.; Delgado, J.; Mickler, P. J.; Horvoka, S.; Trevino, R.

2015-12-01

One concern related to GCS is possible risk of unintended CO2 leakage from the storage formations into overlying potable aquifers on underground sources of drinking water (USDW). Here we present a series of field tests conducted in an alluvial aquifer which is on a river terrace at The University of Texas Brackenridge Field Laboratory. Several shallow groundwater wells were completed to the limestone bedrock at a depth of 6 m and screened in the lower 3 m. Core sediments recovered from the shallow aquifer show that the sediments vary in grain size from clay-rich layers to coarse sandy gravels. Two main types of field tests were conducted at the BFL: single- (or double-) well push-pull test and pulse-like CO2 release test. A single- (or double-) well push-pull test includes three phases: the injection phase, the resting phase and pulling phase. During the injection phase, groundwater pumped from the shallow aquifer was stored in a tank, equilibrated with CO2 gasand then injected into the shallow aquifer to mimic CO2 leakage. During the resting phase, the groundwater charged with CO2 reacted with minerals in the aquifer sediments. During the pulling phase, groundwater was pumped from the injection well and groundwater samples were collected continuously for groundwater chemistry analysis. In such tests, large volume of groundwater which was charged with CO2 can be injected into the shallow aquifer and thus maximize contact of groundwater charged with CO2. Different than a single- (or double-) well push-pull test, a pulse-like CO2 release test for validating chemical sensors for CO2 leakage detection involves a CO2 release phase that CO2 gas was directly bubbled into the testing well and a post monitoring phase that groundwater chemistry was continuously monitored through sensors and/or grounder sampling. Results of the single- (or double-) well push-pull tests conducted in the shallow aquifer shows that the unintended CO2 leakage could lead to dissolution of carbonates and some silicates and mobilization of heavy metals from the aquifer sediments to groundwater, however, such mobilization posed no risks on groundwater quality at this site. The pulse-like tests have demonstrated it is plausible to use chemical sensors for CO2 leakage detection in groundwater.

Influence of imbalance on distortion in optical push-pull frontends

NASA Astrophysics Data System (ADS)

Hagensen, Morten

1995-04-01

The influence of imbalance on second-order inter-modulation distortion (IMD2) in optical push-pull frontends for Subcarrier Multiplex CATV applications is investigated theoretically and experimentally. The investigation focuses on imbalance introduced in either the photodiode, the push-pull amplifier, or the output balun, and expressions describing the overall IMD2 cancellation efficiency are derived. The developed theory is used to predict the IMD2 cancellation behavior of an optical push-pull fronted. Commercially available PIN photodiodes for CATV purposes and ferrite core transformers are characterised for phase and amplitude balance up to 1 GHz. The overall IMD2 cancellation efficiency of an optical push-pull frontend based on the best of these devices is calculated. The theory is finally verified experimentally with an optical push-pull frontend designed with the characterised photodiode and transformer. The improvement in IMD2 suppression obtained with the push-pull structure relative to a single-ended structure is in average 29 dB across the band from 47-862 MHz. The total IMD2 suppression obtained for the frontend is between 60 dBc and 79 dBc at an average optical input power of 1 mW and with an optical modulation index (OMI) of 35% per carrier in a two-tone setup.

Influence of molecular designs on polaronic and vibrational transitions in a conjugated push-pull copolymer

NASA Astrophysics Data System (ADS)

Cobet, Christoph; Gasiorowski, Jacek; Menon, Reghu; Hingerl, Kurt; Schlager, Stefanie; White, Matthew S.; Neugebauer, Helmut; Sariciftci, N. Serdar; Stadler, Philipp

2016-10-01

Electron-phonon interactions of free charge-carriers in doped pi-conjugated polymers are conceptually described by 1-dimensional (1D) delocalization. Thereby, polaronic transitions fit the 1D-Froehlich model in quasi-confined chains. However, recent developments in conjugated polymers have diversified the backbones to become elaborate heterocylcic macromolecules. Their complexity makes it difficult to investigate the electron-phonon coupling. In this work we resolve the electron-phonon interactions in the ground and doped state in a complex push-pull polymer. We focus on the polaronic transitions using in-situ spectroscopy to work out the differences between single-unit and push-pull systems to obtain the desired structural- electronic correlations in the doped state. We apply the classic 1D-Froehlich model to generate optical model fits. Interestingly, we find the 1D-approach in push-pull polarons in agreement to the model, pointing at the strong 1D-character and plain electronic structure of the push-pull structure. In contrast, polarons in the single-unit polymer emerge to a multi- dimensional problem difficult to resolve due to their anisotropy. Thus, we report an enhancement of the 1D-character by the push-pull concept in the doped state - an important view in light of the main purpose of push-pull polymers for photovoltaic devices.

Towards electrochromic devices having visible color switching using electronic push-push and push-pull cinnamaldehyde derivatives.

PubMed

Navarathne, Daminda; Skene, W G

2013-12-11

A series of symmetric and unsymmetric conjugated azomethines derived from cinnamaldehyde and 2,5-diaminothiophene-3,4-dicarboxylic acid diethyl ester were prepared. The optical, electrochemical, and spectroelectrochemical properties of the electronic push-pull and push-push triads were investigated. Their properties could be tuned contingent on the cinnamaldehyde's electron withdrawing and donating substituents. The push-push symmetric derivative exhibited positive solvatochromism with the absorbance spanning some 31 nm, depending on the solvent polarity. Solvent dependent spectroelectrochemistry was also found for the symmetric push-push azomethine. The color of the neutral state and radical cation spanned 215 nm. The most pronounced color transition of the purple colored material was found in dimethyl sulfoxide (DMSO), where the color bleached with electrochemical oxidation. This was a result of the absorbance shifting into the near infrared (NIR) and not from decomposition of the azomethine. Electrochromic devices with the azomethines possessing desired reversible oxidation and color changes in the visible were fabricated and tested to demonstrate the applicability of these azomethine triads in devices.

Automatic control of oscillatory penetration apparatus

DOEpatents

Lucon, Peter A

2015-01-06

A system and method for controlling an oscillatory penetration apparatus. An embodiment is a system and method for controlling a sonic drill having a displacement and an operating range and operating at a phase difference, said sonic drill comprising a push-pull piston and eccentrics, said method comprising: operating the push-pull piston at an initial push-pull force while the eccentrics are operated at a plurality of different operating frequencies within the operating range of the sonic drill and measuring the displacement at each operating frequency; determining an efficient operating frequency for the material being drilled and operating the eccentrics at said efficient operating frequency; determining the phase difference at which the sonic drill is operating; and if the phase difference is not substantially equal to minus ninety degrees, operating the push-pull piston at another push-pull force.

Causal assessment of occupational pushing or pulling and low back pain: results of a systematic review.

PubMed

Roffey, Darren M; Wai, Eugene K; Bishop, Paul; Kwon, Brian K; Dagenais, Simon

2010-06-01

Low back pain (LBP) is a prevalent and expensive musculoskeletal condition that predominantly occurs in working-age individuals of industrialized nations. Although numerous occupational physical activities have been implicated in its etiology, determining the causation of occupational LBP still remains a challenge. To conduct a systematic review evaluating the causal relationship between occupational pushing or pulling and LBP. Systematic review of the literature. Studies reporting an association between occupational pushing or pulling and LBP. Numerical association between exposure to pushing or pulling and the presence of LBP. A systematic review was performed to identify, evaluate, and summarize the literature related to establishing a causal relationship, according to Bradford-Hill criteria for causation for occupational pushing or pulling and LBP. A search was conducted using Medline, EMBASE, CINAHL, Cochrane Library, and OSH-ROM, gray literature, hand-searching occupational health journals, reference lists of included studies, and expert knowledge. Methodological quality was assessed using a modified Newcastle-Ottawa Scale. This search yielded 2,766 citations. Thirteen studies met the inclusion criteria. Eight were high-quality studies and five were low-quality studies. There was conflicting evidence with one high-quality study demonstrating a positive association between occupational pushing or pulling and LBP and five studies showing no relationship. One study reported a nonstatistically significant dose-response trend, four studies discussed temporality of which one indicated a positive finding, two studies discussed the biological plausibility of a causal link between occupational pushing or pulling and LBP, and no evidence was uncovered to assess the experiment criterion. A qualitative summary of existing studies was not able to find any high-quality studies that fully satisfied any of the Bradford-Hill causation criteria for occupational pushing or pulling and LBP. Based on the evidence reviewed, it is unlikely that occupational pushing or pulling is independently causative of LBP in the populations of workers studied. Copyright 2010 Elsevier Inc. All rights reserved.

78 FR 24368 - Airworthiness Directives; Bell Helicopter Textron, Inc. (Bell) Model Helicopters

Federal Register 2010, 2011, 2012, 2013, 2014

2013-04-25

... chain and cable control system with a push-pull control system. Since we issued that AD, we have... requires replacing the existing chain and cable control system with a push-pull control system. Both... Model 205A-1 to replace the tail rotor chain and cable control system with a push-pull control system...

Are pushing and pulling work-related risk factors for upper extremity symptoms? A systematic review of observational studies.

PubMed

Hoozemans, M J M; Knelange, E B; Frings-Dresen, M H W; Veeger, H E J; Kuijer, P P F M

2014-11-01

Systematically review observational studies concerning the question whether workers that perform pushing/pulling activities have an increased risk for upper extremity symptoms as compared to workers that perform no pushing/pulling activities. A search in MEDLINE via PubMed and EMBASE was performed with work-related search terms combined with push/pushing/pull/pulling. Studies had to examine exposure to pushing/pulling in relation to upper extremity symptoms. Two authors performed the literature selection and assessment of the risk of bias in the studies independently. A best evidence synthesis was used to draw conclusions in terms of strong, moderate or conflicting/insufficient evidence. The search resulted in 4764 studies. Seven studies were included, with three of them of low risk of bias, in total including 8279 participants. A positive significant relationship with upper extremity symptoms was observed in all four prospective cohort studies with effect sizes varying between 1.5 and 4.9. Two out of the three remaining studies also reported a positive association with upper extremity symptoms. In addition, significant positive associations with neck/shoulder symptoms were found in two prospective cohort studies with effect sizes of 1.5 and 1.6, and with shoulder symptoms in one of two cross-sectional studies with an effect size of 2.1. There is strong evidence that pushing/pulling is related to upper extremity symptoms, specifically for shoulder symptoms. There is insufficient or conflicting evidence that pushing/pulling is related to (combinations of) upper arm, elbow, forearm, wrist or hand symptoms. 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.

Cyclic biomechanical testing of biocomposite lateral row knotless anchors in a human cadaveric model.

PubMed

Barber, F Alan; Bava, Eric D; Spenciner, David B; Piccirillo, Justin

2013-06-01

The purpose of this study was to assess the mechanical performance of biocomposite knotless lateral row anchors based on both anchor design and the direction of pull. Two lateral row greater tuberosity insertion sites (anterior and posterior) were identified in matched pairs of fresh-frozen human cadaveric shoulders DEXA (dual energy X-ray absorptiometry) scanned to verify comparability. The humeri were stripped of all soft tissue and 3 different biocomposite knotless lateral row anchors: HEALIX Knotless BR (DePuy Mitek, Raynham MA), BioComposite PushLock (Arthrex, Naples, FL), and Bio-SwiveLock (Arthrex). Fifty-two anchors were distributed among the insertion locations and tested them with either an anatomic or axial pull. A fixed-gauge loop (15 mm) of 2 high-strength sutures from each anchor was created. After a 10-Nm preload, anchors were cycled from 10 to 45 Nm at 0.5 Hz for 200 cycles and tested to failure at 4.23 mm/second. The load to reach 3 mm and 5 mm displacement, ultimate failure load, displacement at ultimate failure, and failure mode were recorded. Threaded anchors (Bio-SwiveLock, P = .03; HEALIX Knotless, P = .014) showed less displacement with anatomic testing than did the nonthreaded anchor (BioComposite PushLock), and the HEALIX Knotless showed less overall displacement than did the other 2 anchors. The Bio-SwiveLock exhibited greater failure loads than did the other 2 anchors (P < .05). Comparison of axial and anatomic loading showed no maximum load differences for all anchors as a whole (P = .1084). Yet, anatomic pulling produced higher failure loads than did axial pulling for the Bio-SwiveLock but not for the BioComposite PushLock or the HEALIX Knotless. The nonthreaded anchor (BioComposite PushLock) displayed lower failure loads than did both threaded anchors with axial pulling. Threaded biocomposite anchors (HEALIX Knotless BR and Bio-SwiveLock) show less anatomic loading displacement and higher axial failure loads than do the nonthreaded (BioComposite PushLock) anchor. The HEALIX Knotless BR anchor showed less displacement than did the BioComposite PushLock and Bio-SwiveLock anchors. Neither axial nor anatomic loading had an effect on overall anchor displacement. Because of the strength profiles exhibited, this study supports the use of biocomposite anchors, which have definite advantages over polyetheretherketone (PEEK) and metal products. However, the nonthreaded BioComposite PushLock anchor cannot be recommended. Copyright © 2013 Arthroscopy Association of North America. All rights reserved.

Sunlight-switchable light shutter fabricated using liquid crystals doped with push-pull azobenzene.

PubMed

Oh, Seung-Won; Baek, Jong-Min; Yoon, Tae-Hoon

2016-11-14

We propose a sunlight-switchable light shutter using liquid crystal/polymer composite doped with push-pull azobenzene. The proposed light shutter is switchable between the translucent and transparent states by application of an electric field or by UV irradiation. Switching by UV irradiation is based on the change of the liquid crystal (LC) clearing point by the photo-isomerization effect of push-pull azobenzene. Under sunlight, the light shutter can be switched from the translucent to the transparent state by the nematic-isotropic phase transition of the LC domains triggered by trans-cis photo-isomerization of the push-pull azobenzene molecules. When the amount of sunlight is low because of cloud cover or when there is no sunlight at sunset, the light shutter rapidly relaxes from its transparent state back to its initial translucent state by the isotropic-nematic phase transition induced by cis-trans back-isomerization of the push-pull azobenzene molecules.

Pushing and pulling: an assessment tool for occupational health and safety practitioners.

PubMed

Lind, Carl Mikael

2018-03-01

A tool has been developed for supporting practitioners when assessing manual pushing and pulling operations based on an initiative by two global companies in the manufacturing industry. The aim of the tool is to support occupational health and safety practitioners in risk assessment and risk management of pushing and pulling operations in the manufacturing and logistics industries. The tool is based on a nine-multiplier equation that includes a wide range of factors affecting an operator's health risk and capacity in pushing and pulling. These multipliers are based on psychophysical, physiological and biomechanical studies in combination with judgments from an expert group consisting of senior researchers and ergonomists. In order to consider usability, more than 50 occupational health and safety practitioners (e.g., ergonomists, managers, safety representatives and production personnel) participated in the development of the tool. An evaluation by 22 ergonomists supports that the push/pull tool is user friendly in general.

Pushing and pulling in relation to musculoskeletal disorders: a review of risk factors.

PubMed

Hoozemans, M J; van der Beek, A J; Frings-Dresen, M H; van Dijk, F J; van der Woude, L H

1998-06-01

The objective was to review the literature on risk factors for musculoskeletal disorders related to pushing and pulling. The risk factors have been described and evaluated from four perspectives: epidemiology, psychophysics, physiology, and biomechanics. Epidemiological studies have shown, based on cross-sectional data, that pushing and pulling is associated with low back pain. Evidence with respect to complaints of other parts of the musculoskeletal system is lacking. Risk factors have been found to influence the maximum (acceptable) push or pull forces as well as the physiological and mechanical strain on the human body. The risk factors have been divided into: (a) work situation, such as distance, frequency, handle height, and cart weight, (b) actual working method and posture/movement/exerted forces, such as foot distance and velocity, and (c) worker's characteristics, such as body weight. Longitudinal epidemiological studies are needed to relate pushing and pulling to musculoskeletal disorders.

Biomechanically determined hand force limits protecting the low back during occupational pushing and pulling tasks.

PubMed

Weston, Eric B; Aurand, Alexander; Dufour, Jonathan S; Knapik, Gregory G; Marras, William S

2018-06-01

Though biomechanically determined guidelines exist for lifting, existing recommendations for pushing and pulling were developed using a psychophysical approach. The current study aimed to establish objective hand force limits based on the results of a biomechanical assessment of the forces on the lumbar spine during occupational pushing and pulling activities. Sixty-two subjects performed pushing and pulling tasks in a laboratory setting. An electromyography-assisted biomechanical model estimated spinal loads, while hand force and turning torque were measured via hand transducers. Mixed modelling techniques correlated spinal load with hand force or torque throughout a wide range of exposures in order to develop biomechanically determined hand force and torque limits. Exertion type, exertion direction, handle height and their interactions significantly influenced dependent measures of spinal load, hand force and turning torque. The biomechanically determined guidelines presented herein are up to 30% lower than comparable psychophysically derived limits and particularly more protective for straight pushing. Practitioner Summary: This study utilises a biomechanical model to develop objective biomechanically determined push/pull risk limits assessed via hand forces and turning torque. These limits can be up to 30% lower than existing psychophysically determined pushing and pulling recommendations. Practitioners should consider implementing these guidelines in both risk assessment and workplace design moving forward.

Trunk response and stability in standing under sagittal-symmetric pull-push forces at different orientations, elevations and magnitudes.

PubMed

El Ouaaid, Z; Shirazi-Adl, A; Plamondon, A

2018-03-21

To reduce lifting and associated low back injuries, manual material handling operations often involve pulling-pushing of carts at different weights, orientations, and heights. The loads on spine and risk of injury however need to be investigated. The aim of this study was to evaluate muscle forces, spinal loads and trunk stability in pull-push tasks in sagittal-symmetric, static upright standing posture. Three hand-held load magnitudes (80, 120 and 160 N) at four elevations (0, 20, 40 and 60 cm to the L5-S1) and 24 force directions covering all pull/push orientations were considered. For this purpose, a musculoskeletal finite element model with kinematics measured earlier were used. Results demonstrated that peak spinal forces occur under inclined pull (lift) at upper elevations but inclined push at the lowermost one. Minimal spinal loads, on the other hand, occurred at and around vertical pull directions. Overall, spinal forces closely followed variations in the net external moment of pull-push forces at the L5-S1. Local lumbar muscles were most active in pulls while global extensor muscles in lifts. The trunk stability margin decreased with load elevation except at and around horizontal push; it peaked under pulls and reached minimum at vertical lifts. It also increased with antagonist activity in muscles and intra-abdominal pressure. Results provide insight into the marked effects of variation in the load orientation and elevation on muscle forces, spinal loads and trunk stability and hence offer help in rehabilitation, performance enhancement training and design of safer workplaces. Copyright © 2017 Elsevier Ltd. All rights reserved.

Equivalence Reliability among the FITNESSGRAM[R] Upper-Body Tests of Muscular Strength and Endurance

ERIC Educational Resources Information Center

Sherman, Todd; Barfield, J. P.

2006-01-01

This study was designed to investigate the equivalence reliability between the suggested FITNESSGRAM[R] muscular strength and endurance test, the 90[degrees] push-up (PSU), and alternate FITNESSGRAM[R] tests of upper-body strength and endurance (i.e., modified pull-up [MPU], flexed-arm hang [FAH], and pull-up [PU]). Children (N = 383) in Grades 3…

Three Levels of Push-Pull Dynamics among Chinese International Students' Decision to Study Abroad in the Canadian Context

ERIC Educational Resources Information Center

Chen, Jun Mian

2017-01-01

The extant literature on student migration flows generally focus on the traditional push-pull factors of migration at the individual level. Such a tendency excludes the broader levels affecting international student mobility. This paper proposes a hybrid of three levels of push-pull dynamics (micro-individual decision-making, meso-academic…

AORN ergonomic tool 7: pushing, pulling, and moving equipment on wheels.

PubMed

Waters, Thomas; Lloyd, John D; Hernandez, Edward; Nelson, Audrey

2011-09-01

Pushing and pulling equipment in and around the OR can place high shear force demands on perioperative team members' shoulder and back muscles and joints. These high forces may lead to work-related musculoskeletal disorders. AORN Ergonomic Tool 7: Pushing, Pulling, and Moving Equipment on Wheels can help perioperative team members assess the risk of pushing and pulling tasks in the perioperative setting. The tool provides evidence-based suggestions about when assistive devices should be used for these tasks and is based on current ergonomic safety concepts, scientific evidence, and knowledge of effective technology and procedures, including equipment and devices for safe patient handling. Published by Elsevier Inc.

Push-me-pull-you: how microtubules organize the cell interior

PubMed Central

2008-01-01

Dynamic organization of the cell interior, which is crucial for cell function, largely depends on the microtubule cytoskeleton. Microtubules move and position organelles by pushing, pulling, or sliding. Pushing forces can be generated by microtubule polymerization, whereas pulling typically involves microtubule depolymerization or molecular motors, or both. Sliding between a microtubule and another microtubule, an organelle, or the cell cortex is also powered by molecular motors. Although numerous examples of microtubule-based pushing and pulling in living cells have been observed, it is not clear why different cell types and processes employ different mechanisms. This review introduces a classification of microtubule-based positioning strategies and discusses the efficacy of pushing and pulling. The positioning mechanisms based on microtubule pushing are efficient for movements over small distances, and for centering of organelles in symmetric geometries. Mechanisms based on pulling, on the other hand, are typically more elaborate, but are necessary when the distances to be covered by the organelles are large, and when the geometry is asymmetric and complex. Thus, taking into account cell geometry and the length scale of the movements helps to identify general principles of the intracellular layout based on microtubule forces. PMID:18404264

Determinants and magnitudes of manual force strengths and joint moments during two-handed standing maximal horizontal pushing and pulling.

PubMed

Chow, Amy Y; Dickerson, Clark R

2016-04-01

Pushing and pulling are common occupational exertions that are increasingly associated with musculoskeletal complaints. This study focuses on the sensitivity of shoulder capacity to gender, handle height, exertion type (push or pull) and handle orientation for these tasks. All factors except for handle orientation influenced unilateral and total manual force strength (p < 0.01), with exertion type being the most influential. Interaction effects also existed between handle height and exertion type. Additionally, joint moments at the shoulders and low back were influenced by all factors studied (p < 0.01), with exertion type again being most influential. Knowledge of the relative influence of multiple factors on shoulder capacity can provide guidance regarding these factors when designing or evaluating occupational pushing and pulling tasks for a diverse population. Practitioner Summary: pushing and pulling comprise nearly half of all manual materials handling tasks. Practitioners often assess, design or modify these tasks while incorporating constraints, including manual force direction and handle interface. This study provides guidance to aid design of pushing and pulling tasks in the context of shoulder physical capacity.

Additive manufactured push-fit implant fixation with screw-strength pull out.

PubMed

van Arkel, Richard J; Ghouse, Shaaz; Milner, Piers E; Jeffers, Jonathan R T

2017-10-11

Additive manufacturing offers exciting new possibilities for improving long-term metallic implant fixation in bone through enabling open porous structures for bony ingrowth. The aim of this research was to investigate how the technology could also improve initial fixation, a precursor to successful long-term fixation. A new barbed fixation mechanism, relying on flexible struts was proposed and manufactured as a push-fit peg. The technology was optimized using a synthetic bone model and compared with conventional press-fit peg controls tested over a range of interference fits. Optimum designs, achieving maximum pull-out force, were subsequently tested in a cadaveric femoral condyle model. The barbed fixation surface provided more than double the pull-out force for less than a third of the insertion force compared to the best performing conventional press-fit peg (p < 0.001). Indeed, it provided screw-strength pull out from a push-fit device (1,124 ± 146 N). This step change in implant fixation potential offers new capabilities for low profile, minimally invasive implant design, while providing new options to simplify surgery, allowing for one-piece push-fit components with high levels of initial stability. © 2017 The Authors. Journal of Orthopaedic Research Published by WileyPeriodicals, Inc. on behalf of the Orthopaedic Research Society. J Orthop Res 9999:1-11, 2017. © 2017 The Authors. Journal of Orthopaedic Research Published by WileyPeriodicals, Inc. on behalf of the Orthopaedic Research Society.

Slab-pull and slab-push earthquakes in the Mexican, Chilean and Peruvian subduction zones

NASA Astrophysics Data System (ADS)

Lemoine, A.; Madariaga, R.; Campos, J.

2002-09-01

We studied intermediate depth earthquakes in the Chile, Peru and Mexican subduction zones, paying special attention to slab-push (down-dip compression) and slab-pull (down-dip extension) mechanisms. Although, slab-push events are relatively rare in comparison with slab-pull earthquakes, quite a few have occurred recently. In Peru, a couple slab-push events occurred in 1991 and one slab-pull together with several slab-push events occurred in 1970 near Chimbote. In Mexico, several slab-push and slab-pull events occurred near Zihuatanejo below the fault zone of the 1985 Michoacan event. In central Chile, a large M=7.1 slab-push event occurred in October 1997 that followed a series of four shallow Mw>6 thrust earthquakes on the plate interface. We used teleseismic body waveform inversion of a number of Mw>5.9 slab-push and slab-pull earthquakes in order to obtain accurate mechanisms, depths and source time functions. We used a master event method in order to get relative locations. We discussed the occurrence of the relatively rare slab-push events in the three subduction zones. Were they due to the geometry of the subduction that produces flexure inside the downgoing slab, or were they produced by stress transfer during the earthquake cycle? Stress transfer can not explain the occurence of several compressional and extensional intraplate intermediate depth earthquakes in central Chile, central Mexico and central Peru. It seemed that the heterogeneity of the stress field produced by complex slab geometry has an important influence on intraplate intermediate depth earthquakes.

Inclusion at Risk? Push- and Pull-Out Phenomena in Inclusive School Systems: The Italian and Norwegian Experiences

ERIC Educational Resources Information Center

Nes, Kari; Demo, Heidrun; Ianes, Dario

2018-01-01

The main objective of this article is to explore and compare research data on pull-out and push-out phenomena within inclusive school systems, discussing if and how they represent a risk for inclusion. The terms pull-out and push-out refer to situations in which some groups of students in regular schools learn in settings apart from their peers.…

On Reducing Delay in Mesh-Based P2P Streaming: A Mesh-Push Approach

NASA Astrophysics Data System (ADS)

Liu, Zheng; Xue, Kaiping; Hong, Peilin

The peer-assisted streaming paradigm has been widely employed to distribute live video data on the internet recently. In general, the mesh-based pull approach is more robust and efficient than the tree-based push approach. However, pull protocol brings about longer streaming delay, which is caused by the handshaking process of advertising buffer map message, sending request message and scheduling of the data block. In this paper, we propose a new approach, mesh-push, to address this issue. Different from the traditional pull approach, mesh-push implements block scheduling algorithm at sender side, where the block transmission is initiated by the sender rather than by the receiver. We first formulate the optimal upload bandwidth utilization problem, then present the mesh-push approach, in which a token protocol is designed to avoid block redundancy; a min-cost flow model is employed to derive the optimal scheduling for the push peer; and a push peer selection algorithm is introduced to reduce control overhead. Finally, we evaluate mesh-push through simulation, the results of which show mesh-push outperforms the pull scheduling in streaming delay, and achieves comparable delivery ratio at the same time.

Centrifuge training program with "push-pull" elements.

PubMed

Mikuliszyn, Romuald; Zebrowski, Mariusz; Kowalczuk, Krzysztof

2005-05-01

Pilots of fighter aircraft are often exposed to maneuvers that produce negative acceleration (-Gz) immediately followed by positive acceleration (+Gz). This sequence has been found to reduce tolerance to +Gz, a phenomenon known as the "push-pull" effect. We devised a centrifuge training program to demonstrate this phenomenon to pilots. The centrifuge of the Military Institute of Aviation Medicine in Warsaw, Poland, was modified in 1996 to allow active positioning of the gondola during rotation. Head-down position of -6 degrees to -40 degrees were used to produce relative -Gz (r-Gz) in a range down to 0.2. As a side effect, this produces Gy acceleration between -1.3 Gy and -1.6 Gy. Pilots completed normal centrifuge training, including a relaxed, gradual-onset run and three rapid-onset runs. They were then exposed to a profile that included a series of push-pull exposures where r-Gz was followed by +Gz with stepwise increases in the latter from +2.5 to +5 Gz. The final profile was a simulated aerial combat maneuver with push-pull elements. The trainees expressed surprise at the push-pull effect, which forced them to begin an anti-G straining maneuver at lower levels than normal. They complained about the presence of the Gy, which rarely occurs in aircraft. This type of profile appears useful for training pilots about the push-pull phenomenon. After collection of additional data, the profiles may be refined.

Field Evaluation of a Push-Pull System to Reduce Malaria Transmission

PubMed Central

Menger, David J.; Omusula, Philemon; Holdinga, Maarten; Homan, Tobias; Carreira, Ana S.; Vandendaele, Patrice; Derycke, Jean-Luc; Mweresa, Collins K.; Mukabana, Wolfgang Richard; van Loon, Joop J. A.; Takken, Willem

2015-01-01

Malaria continues to place a disease burden on millions of people throughout the tropics, especially in sub-Saharan Africa. Although efforts to control mosquito populations and reduce human-vector contact, such as long-lasting insecticidal nets and indoor residual spraying, have led to significant decreases in malaria incidence, further progress is now threatened by the widespread development of physiological and behavioural insecticide-resistance as well as changes in the composition of vector populations. A mosquito-directed push-pull system based on the simultaneous use of attractive and repellent volatiles offers a complementary tool to existing vector-control methods. In this study, the combination of a trap baited with a five-compound attractant and a strip of net-fabric impregnated with micro-encapsulated repellent and placed in the eaves of houses, was tested in a malaria-endemic village in western Kenya. Using the repellent delta-undecalactone, mosquito house entry was reduced by more than 50%, while the traps caught high numbers of outdoor flying mosquitoes. Model simulations predict that, assuming area-wide coverage, the addition of such a push-pull system to existing prevention efforts will result in up to 20-fold reductions in the entomological inoculation rate. Reductions of such magnitude are also predicted when mosquitoes exhibit a high resistance against insecticides. We conclude that a push-pull system based on non-toxic volatiles provides an important addition to existing strategies for malaria prevention. PMID:25923114

Microcatheter entrapment retrieval from Onyx embolization in brain arteriovenous malformations: A technical note.

PubMed

Vu, Phat D; Grigorian, Arthur A

2015-10-01

Many techniques have been use for retrieval of an entrapped microcatheter during Onyx (eV3 Neurovascular) embolization of brain arteriovenous malformations (BAVMs). We report our technique that we term "pull-push-pull" that can be utilized as first management in retrieving the microcatheter. We analyzed a total of 37 patients that underwent BAVM embolization with either Onyx 18 or 34 at our institution. Standard embolization techniques were utilized with the use of Marathon (eV3 Neurovascular) microcatheter. When difficulty in retrieving the microcatheter arose, we used the "pull-push-pull" technique. The technique comprises the eV3 protocol of retraction. In addition, the microcatheter is stretched causing the Onyx cast to stretch in its inner core, creating a more thorough cohesive property amongst the Onyx mixture. Then the microcatheter is pushed back and to its point of embolization origin. Afterwards, retraction of the microcatheter is enabled as it can be easily dislodged from the cast. Multiple attempts can be repeated as needed. We had three patients that had difficulty with removal of microcatheter (8.1%). Utilization of the "pull-push-pull" technique was used on two of those patients. No neurological complication was observed with our technique. We believe the cohesive property of Onyx solution helps in the retrieval of the catheter by our method and technique. We believe the "pull-push-pull" can be utilized and be an additional technique before attempting other catheter retrieval techniques in Onyx BAVM embolization. © The Author(s) 2015.

Pulse width modulated push-pull driven parallel resonant converter with active free-wheel

DOEpatents

Reass, William A.; Schrank, Louis

2004-06-22

An apparatus and method for high frequency alternating power generation to control kilowatts of supplied power in microseconds. The present invention includes a means for energy storage, push-pull switching means, control electronics, transformer means, resonant circuitry and means for excess energy recovery, all in electrical communication. A push-pull circuit works synchronously with a force commutated free-wheel transistor to provide current pulses to a transformer. A change in the conduction angle of the push-pull circuit changes the amount of energy coupled into the transformer's secondary oscillating circuit, thereby altering the induced secondary resonating voltage. At the end of each pulse, the force commutated free-wheel transistor causes residual excess energy in the primary circuit to be transmitted back to the storage capacitor for later use.

Common-pull, multiple-push, vacuum-activated telescope mirror cell.

PubMed

Ruiz, Elfego; Sohn, Erika; Salas, Luis; Luna, Esteban; Araiza-Durán, José A

2014-11-20

A new concept for push-pull active optics is presented, where the push-force is provided by means of individual airbag type actuators and a common force in the form of a vacuum is applied to the entire back of the mirror. The vacuum provides the pull-component of the system, in addition to gravity. Vacuum is controlled as a function of the zenithal angle, providing correction for the axial component of the mirror's weight. In this way, the push actuators are only responsible for correcting mirror deformations, as well as for supporting the axial mirror weight at the zenith, allowing for a uniform, full dynamic-range behavior of the system along the telescope's pointing range. This can result in the ability to perform corrections of up to a few microns for low-order aberrations. This mirror support concept was simulated using a finite element model and was tested experimentally at the 2.12 m San Pedro Mártir telescope. Advantages such as stress-free attachments, lighter weight, large actuator area, lower system complexity, and lower required mirror-cell stiffness could make this a method to consider for future large telescopes.

Push-pull aminobithiophenes--highly fluorescent stable fluorophores.

PubMed

Dong, Yanmei; Bolduc, Andréanne; McGregor, Nicholas; Skene, W G

2011-04-01

Stable 2-aminobithiophenes were prepared using the Gewald reaction. The resulting push-pull bithiophenes exhibited both unprecedented high fluorescence yields and stability in addition to demonstrating fluorescence on-off properties.

Push and pull strategies: applications for health care marketing.

PubMed

Kingsley, B R

1987-08-01

As health care markets mature and expand, strategies available in other industries become useful. This article examines how traditional push-pull strategies apply to health care. Marketers using a push strategy recognize that the sale of their services or goods is dependent upon the endorsement of a middleman and promote their product through the middleman. Those using a pull strategy market directly to the consumer. In this article, the author outlines the advantages and disadvantages of using each strategy.

Assessment of Anaerobic Metabolic Activity and Microbial Diversity in a Petroleum-Contaminated Aquifer Using Push-Pull Tests in Combination With Molecular Tools and Stable Isotopes

NASA Astrophysics Data System (ADS)

Schroth, M. H.; Kleikemper, J.; Pombo, S. A.; Zeyer, J.

2002-12-01

In the past, studies on microbial communities in natural environments have typically focused on either their structure or on their metabolic function. However, linking structure and function is important for understanding microbial community dynamics, in particular in contaminated environments. We will present results of a novel combination of a hydrogeological field method (push-pull tests) with molecular tools and stable isotope analysis, which was employed to quantify anaerobic activities and associated microbial diversity in a petroleum-contaminated aquifer in Studen, Switzerland. Push-pull tests consisted of the injection of test solution containing a conservative tracer and reactants (electron acceptors, 13C-labeled carbon sources) into the aquifer anoxic zone. Following an incubation period, the test solution/groundwater mixture was extracted from the same location. Metabolic activities were computed from solute concentrations measured during extraction. Simultaneously, microbial diversity in sediment and groundwater was characterized by using fluorescence in situ hybridization (FISH), denaturing gradient gel electrophoresis (DGGE), as well as phospholipids fatty acid (PLFA) analysis in combination with 13C isotopic measurements. Results from DGGE analyses provided information on the general community structure before, during and after the tests, while FISH yielded information on active populations. Moreover, using 13C-labeling of microbial PLFA we were able to directly link carbon source assimilation in an aquifer to indigenous microorganisms while providing quantitative information on respective carbon source consumption.

Push-pull farming systems.

PubMed

Pickett, John A; Woodcock, Christine M; Midega, Charles A O; Khan, Zeyaur R

2014-04-01

Farming systems for pest control, based on the stimulo-deterrent diversionary strategy or push-pull system, have become an important target for sustainable intensification of food production. A prominent example is push-pull developed in sub-Saharan Africa using a combination of companion plants delivering semiochemicals, as plant secondary metabolites, for smallholder farming cereal production, initially against lepidopterous stem borers. Opportunities are being developed for other regions and farming ecosystems. New semiochemical tools and delivery systems, including GM, are being incorporated to exploit further opportunities for mainstream arable farming systems. By delivering the push and pull effects as secondary metabolites, for example, (E)-4,8-dimethyl-1,3,7-nonatriene repelling pests and attracting beneficial insects, problems of high volatility and instability are overcome and compounds are produced when and where required. Copyright © 2013 The Authors. Published by Elsevier Ltd.. All rights reserved.

A three-dimensional computerized isometric strength measurement system.

PubMed

Black, Nancy L; Das, Biman

2007-05-01

The three-dimensional Computerized Isometric Strength Measurement System (CISMS) reliably and accurately measures isometric pull and push strengths in work spaces of paraplegic populations while anticipating comparative studies with other populations. The main elements of the system were: an extendable arm, a vertical supporting track, a rotating platform, a force transducer, stability sensors and a computerized data collection interface. The CISMS with minor modification was successfully used to measure isometric push-up and pull-down strengths of paraplegics and isometric push, pull, push-up and pull-down strength in work spaces for seated and standing able-bodied populations. The instrument has satisfied criteria of versatility, safety and comfort, ease of operation, and durability. Results are accurate within 2N for aligned forces. Costing approximately $1,500 (US) including computer, the system is affordable and accurate for aligned isometric strength measurements.

Initial Assessment of the Acceptability of a Push-Pull Aedes aegypti Control Strategy in Iquitos, Peru and Kanchanaburi, Thailand

PubMed Central

Paz-Soldan, Valerie A.; Plasai, Valaikanya; Morrison, Amy C.; Rios-Lopez, Esther J.; Guedez-Gonzales, Shirly; Grieco, John P.; Mundal, Kirk; Chareonviriyaphap, Theeraphap; Achee, Nicole L.

2011-01-01

As part of a larger research program evaluating chemical threshold levels for a Push-Pull intervention to reduce man-vector (Aedes aegypti) contact, this qualitative study explored local perceptions and strategies associated with mosquito control within dengue-endemic communities in Peru and Thailand. Focus groups were used to provide preliminary information that would identify possible public acceptance issues to the Push-Pull strategy in each site. Nine focus group discussions (total of 102 individuals) conducted between September 2008 and March 2009 examined several themes: 1) current mosquito control practices; 2) perceptions of spatial repellency and contact irritancy versus killing mosquitoes; and 3) initial perceptions toward mosquito host-seeking traps. Results indicate participants use household-level strategies for insect control that reveal familiarity with the concept of spatial repellent and contact irritant actions of chemicals and that placing traps in the peridomestic environment to remove repelled mosquitoes was acceptable. Preliminary evidence suggests a Push-Pull strategy should be well accepted in these locations. These results will be beneficial for developing future large scale push-pull interventions and are currently being used to guide insecticide application strategies in (entomological) proof-of-concept studies using experimental huts. PMID:21292886

Push versus pull gastrostomy in cancer patients: A single center retrospective analysis of complications and technical success rates.

PubMed

Currie, B M; Getrajdman, G I; Covey, A M; Alago, W; Erinjeri, J P; Maybody, M; Boas, F E

2018-04-28

To compare the technical success and complication rates of push versus pull gastrostomy tubes in cancer patients, and to examine their dependence on operator experience. A retrospective review was performed of 304 cancer patients (170 men, 134 women; mean age 60.3±12.6 [SD], range: 19-102 years) referred for primary gastrostomy tube placement, 88 (29%) of whom had a previously unsuccessful attempt at percutaneous endoscopic gastrostomy (PEG) placement. Analyzed variables included method of insertion (push versus pull), indication for gastrostomy, technical success, operator experience, and procedure-related complications within 30 days of placement. Gastrostomy tubes were placed for feeding in 189 patients and palliative decompression in 115 patients. Technical success was 91%: 78% after endoscopy had previously been unsuccessful and 97% when excluding failures associated with prior endoscopy. In the first 30 days, there were 29 minor complications (17.2%) associated with push gastrostomies, and only 8 minor complications (7.5%) with pull gastrostomies (P<0.05). There was no significant difference in major complications (push gastrostomy 5.3%, pull gastrostomy 5.6%). For decompressive gastrostomy tubes, the pull technique resulted in lower rates of both minor and major complications. There was no difference in complications or technical success rates for more versus less experienced operators. Pull gastrostomy tube placement had a lower rate of complications than push gastrostomy tube placement, especially when the indication was decompression. The technical success rate was high, even after a failed attempt at endoscopic placement. Both the rates of success and complications were independent of operator experience. Copyright © 2018 Société française de radiologie. Published by Elsevier Masson SAS. All rights reserved.

Optical Pulling and Pushing Forces in Bilayer P T -Symmetric Structures

NASA Astrophysics Data System (ADS)

Alaee, Rasoul; Christensen, Johan; Kadic, Muamer

2018-01-01

We investigate the optical force exerted on a parity-time-symmetric bilayer made of balanced gain and loss. We show that an asymmetric optical pulling or pushing force can be exerted on this system depending on the direction of impinging light. The optical pulling or pushing force has a direct physical link to the optical characteristics embedded in the non-Hermitian bilayer. Furthermore, we suggest taking advantage of the optically generated asymmetric force to launch vibrations of an arbitrary shape, which is useful for the contactless probing of mechanical deformations.

"Location is surprisingly a lot more important than you think": a critical thematic analysis of push and pull factor messaging used on Caribbean offshore medical school websites.

PubMed

Morgan, Jeffrey; Crooks, Valorie A; Sampson, Carla Jackie; Snyder, Jeremy

2017-06-02

Offshore medical schools are for-profit, private enterprises located in the Caribbean that provide undergraduate medical education to students who must leave the region for postgraduate training and also typically to practice. This growing industry attracts many medical students from the US and Canada who wish to return home to practice medicine. After graduation, international medical graduates can encounter challenges obtaining residency placements and can face other barriers related to practice. We conducted a qualitative thematic analysis to discern the dominant messages found on offshore medical school websites. Dominant messages included frequent references to push and pull factors intended to encourage potential applicants to consider attending an offshore medical school. We reviewed 38 English-language Caribbean offshore medical school websites in order to extract and record content pertaining to push and pull factors. We found two push and four pull factors present across most offshore medical school websites. Push factors include the: shortages of physicians in the US and Canada that require new medical trainees; and low acceptance rates at medical schools in intended students' home countries. Pull factors include the: financial benefits of attending an offshore medical school; geographic location and environment of training in the Caribbean; training quality and effectiveness; and the potential to practice medicine in one's home country. This analysis contributes to our understanding of some of the factors behind students' decisions to attend an offshore medical school. Importantly, push and pull factors do not address the barriers faced by offshore medical school graduates in finding postgraduate residency placements and ultimately practicing elsewhere. It is clear from push and pull factors that these medical schools heavily focus messaging and marketing towards students from the US and Canada, which raises questions about who benefits from this offshoring practice.

Hyperpolarizabilities of Push-Pull Polyenes: Experimental Results and a New Two-State Model

NASA Technical Reports Server (NTRS)

Perry, J.; Bourhill, G.; Marder, S.; Lu, D.; Chen, G.; Goddard, W.

1994-01-01

Recent work has demonstrated a correlation between the geometry (i.e., the bond length alteration, BLA) and the first and second hyperpolarizabilities (betta and gamma) of donor-acceptor substituted (push-pull)polyenes.

Motivation and Perception of Tourists as Push and Pull Factors to Visit National Park

NASA Astrophysics Data System (ADS)

Said, Jumrin; Maryono

2018-02-01

Push-pull theoretical framework is a popular theory to explain the reason why the tourists decide to visit the destination rather than other place, the kind of experience they want to get and the type of activity they want to do. In this paper, it is explained the motivation as push factors and the perception as pull factors of the tourist in deciding the destination based on previous literature and research using descriptive method. The framework asumed that tourists are motivated to fulfill their needs, including to reduce the psychological imbalance and to gain recognition of social status. National Park is one of destination based on nature or commonly knowns as ecotourism. In choosing the destination, the tourists tend to classify their alternative choice based on several criteria, such as the domination perception of tourist from one destination (pull factor), self motivation (push factor) and the available time and money (situational constraints).

A High-Efficiency Organic Solar Cell Enabled by the Strong Intramolecular Electron Push-Pull Effect of the Nonfullerene Acceptor.

PubMed

Li, Wanning; Ye, Long; Li, Sunsun; Yao, Huifeng; Ade, Harald; Hou, Jianhui

2018-04-01

Besides broadening of the absorption spectrum, modulating molecular energy levels, and other well-studied properties, a stronger intramolecular electron push-pull effect also affords other advantages in nonfullerene acceptors. A strong push-pull effect improves the dipole moment of the wings in IT-4F over IT-M and results in a lower miscibility than IT-M when blended with PBDB-TF. This feature leads to higher domain purity in the PBDB-TF:IT-4F blend and makes a contribution to the better photovoltaic performance. Moreover, the strong push-pull effect also decreases the vibrational relaxation, which makes IT-4F more promising than IT-M in reducing the energetic loss of organic solar cells. Above all, a power conversion efficiency of 13.7% is recorded in PBDB-TF:IT-4F-based devices. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Myogenic origin of the hypotension induced by rapid changes in posture in awake dogs following autonomic blockade

PubMed Central

Wong, Brett J.; Sheriff, Don D.

2008-01-01

The “push-pull” effect denotes the reduced tolerance to +Gz (hypergravity) when +Gz stress is preceded by exposure to hypogravity, i.e., fractional, zero, or negative Gz. The purpose of this study was to test the hypothesis that an exaggerated, myogenically mediated rise in leg vascular conductance contributes to the push-pull effect, using heart level arterial blood pressure as a measure of G tolerance. The approach was to impose control (30 s of 30° head-up tilt) and push-pull (30 s of 30° head-up tilt immediately preceded by 10 s of −15° head-down tilt) gravitational stress after administration of hexamethonium (5 mg/kg) to inhibit autonomic ganglionic neurotransmission in seven dogs. Cardiac output or thigh level arterial pressure (myogenic stimulus) was maintained constant by computer-controlled ventricular pacing. The animals were sedated with acepromazine and lightly restrained in lateral recumbency on a tilt table. Following the onset of head-up tilt, the magnitude of the fall in heart level arterial pressure from baseline was −11.6 ± 2.9 and −17.1 ± 2.2 mmHg for the control and push-pull trials, respectively (P < 0.05), when cardiac output was maintained constant. Over 40% of the exaggerated fall in heart level arterial pressure was attributable to an exaggerated rise in hindlimb vascular conductance (P < 0.05). Maintaining thigh level arterial pressure constant abolished the exaggerated rise in hindlimb blood flow. Thus a push-pull effect largely attributable to a myogenically induced rise in leg vascular conductance occurs when autonomic function is inhibited. PMID:18927267

Relationship between shoulder roll and hand propulsion in the front crawl stroke.

PubMed

Kudo, Shigetada; Sakurai, Yoshihisa; Miwa, Takahiro; Matsuda, Yuji

2017-05-01

This study re-evaluated the magnitude of hand propulsion (HP) in the pull and push phases of the front crawl stroke and investigated the association between the angular velocity of shoulder roll (ω SR ) and hand propulsive lift (HP L ). ω SR was computed in the plane normal to a forward direction for 16 skilled swimmers performing the front crawl stroke at a maximal sprinting pace. HP, hand propulsive drag (HP D ) and HP L were determined by a dynamic pressure approach. HP and HP D in the pull phase were greater than in the push phase (P < 0.05) while HP L in the pull phase was similar to that in the push phase. Eleven swimmers out of the 16 swimmers had a significant within-swimmers correlation between ω SR and HP L in the push phase (P < 0.05). That is, HP L increased in the push phase as the ω SR of rolling back to the neutral position became faster. A swimmer should use more drag for hand propulsion in the pull phase and propulsion from drag and lift equally in the push phase. Based on the relationship between ω SR and HP L in the push phase, a possible stroke technique to enhance HP L using ω SR is discussed.

Optical pulling and pushing forces exerted on silicon nanospheres with strong coherent interaction between electric and magnetic resonances.

PubMed

Liu, Hongfeng; Panmai, Mingcheng; Peng, Yuanyuan; Lan, Sheng

2017-05-29

We investigated theoretically and numerically the optical pulling and pushing forces acting on silicon (Si) nanospheres (NSs) with strong coherent interaction between electric and magnetic resonances. We examined the optical pulling and pushing forces exerted on Si NSs by two interfering waves and revealed the underlying physical mechanism from the viewpoint of electric- and magnetic-dipole manipulation. As compared with a polystyrene (PS) NS, it was found that the optical pulling force for a Si NS with the same size is enlarged by nearly two orders of magnitude. In addition to the optical pulling force appearing at the long-wavelength side of the magnetic dipole resonance, very large optical pushing force is observed at the magnetic quadrupole resonance. The correlation between the optical pulling/pushing force and the directional scattering characterized by the ratio of the forward to backward scattering was revealed. More interestingly, it was found that the high-order electric and magnetic resonances in large Si NSs play an important role in producing optical pulling force which can be generated by not only s-polarized wave but also p-polarized one. Our finding indicates that the strong coherent interaction between the electric and magnetic resonances existing in nanoparticles with large refractive indices can be exploited to manipulate the optical force acting on them and the correlation between the optical force and the directional scattering can be used as guidance. The engineering and manipulation of optical forces will find potential applications in the trapping, transport and sorting of nanoparticles.

Scapular Stabilization and Muscle Strength in Manual Wheelchair Users with Spinal Cord Injury and Subacromial Impingement.

PubMed

Wilbanks, Susan R; Bickel, C Scott

2016-01-01

Background: Manual wheelchair users with spinal cord injury (SCI) are frequently diagnosed with subacromial impingement. Objective: To determine whether the pattern of muscle imbalance and impaired scapular stabilization in able-bodied (AB) adults with impingement is different from that in manual wheelchair users with SCI and impingement. Methods: The following measurements were collected from 22 adults with subacromial impingement (11 SCI, 11 AB): ratio of normalized muscle electrical activity of upper and lower trapezius (UT:LT) during arm abduction; force during abduction, adduction, internal rotation, external rotation, and push and pull; ratios of force for abduction to adduction (AB:ADD), internal to external rotation (IR:ER), and push to pull (PUSH:PULL). Results: Shoulders with impingement had significantly higher UT:LT activation (1.46 ± 0.52) than shoulders without impingement (0.93 ± 0.45) ( P = .006), regardless of wheelchair user status. Significant differences between AB participants and those with SCI were observed for ABD:ADD ( P = .005), PUSH:PULL ( P = .012), and pull strength ( P = .043). Participants with SCI had a significantly greater ABD:ADD (1.37 ± 0.36) than AB participants (1.04 ± 0.22) ( P = .002) and a significantly greater PUSH:PULL (1.53 ± 0.36) than AB participants (1.26 ± 0.18) ( P = .005) because of decreased strength in adduction ( P = .021) and pull ( P = .013). Conclusions: Strategies targeting the posterior shoulder girdle for AB adults are appropriate for manual wheelchair users with SCI and impingement and should focus on scapular retractors and arm adductors with emphasis on scapular depression and posterior tilting.

Impact of hand forces and start/stop frequency on physiological responses to three forms of pushing and pulling: a South African perspective.

PubMed

Ai, Todd

2012-01-01

There has been limited attention given to the physiological demands of pushing and pulling, especially in industrially developing countries such as South Africa. Two key factors affecting the physiological demands of these tasks are the hand forces exerted and the start/stop frequency. The purpose of the current study was therefore to investigate the physiological responses to pushing and pulling at various loads and start/stop frequencies. 36 male subjects participated in the study and were required to complete a total of 18 conditions (three techniques: pushing, two- and one-handed pulling; three loads: 200, 350 and 500 kg; and two frequencies: 2 and 4 stops per minute). During each condition the heart rate, oxygen uptake and energy expenditure were measured. Pushing was found to elicit significantly lower responses for all three dependent variables than either form of pulling. The start/stop frequency was also found to have a significant impact on subject responses. The findings of this study indicate that the technique adopted to maneuver loads is critical in determining the physical demands placed on the human operator. Furthermore increasing the frequency of start/stops plays an important role, thus the forces exerted during these two phases are important from a physiological perspective.

The anomaly in a breakthrough curve of a single well "push-pull" tracer test: A density driven effect?

NASA Astrophysics Data System (ADS)

Zeilfelder, Sarah; Hebig, Klaus; Ito, Narimitsu; Machida, Isao; Scheytt, Traugott; Marui, Atsunao

2013-04-01

What method is appropriate to investigate an aquifer when there is only one well available? A single well "push-pull" tracer test (PP Test) may be a suitable method in order to characterize an aquifer and to obtain information about the hydraulic and chemical properties when only one well is available for the investigations. In a PP test, a test solution that contains a known amount of solutes and a conservative tracer is injected into the aquifer ("push") and extracted afterwards ("pull"). Optionally, the test solution is flushed out of the well and the casing with untreated test solution with a so called "chaser" before being extracted. Also between the injection and the extraction phase a drifting time may be included. The breakthrough of the tracer during the extraction phase is measured and used for analyses and interpretation. In the last three years, several PP Test campaigns were conducted at two different test sites in Japan (Hebig et al. 2011, Zeilfelder et al. 2012). The aim was to investigate the applicability of the PP Test method in different geological settings and in different types of aquifers. The latest field campaign thus focussed on the question how variations of the setup are influencing the breakthrough curve of the PP Test in order to develop and enhance this method. Also the standardization of the PP Test was an aim of this study. During the campaign, a total of seven PP Tests were performed, while only single aspects of the setup were varied from test to test. The tests differed in injection and extraction rate, in the salinity of the injected test solution and in the use of a chaser solution. The general shapes of the breakthrough curves were similar and conclusions about the repeatability of the PP Test could be drawn. However, a sharp anomaly was observed in the breakthrough curve of one specific setup type. By repeating this PP test under the same boundary conditions, we were able to recreate the anomaly and could exclude any technical aspects as a source. In this version of the PP test higher salinized test solution was injected into the aquifer. There are several hypotheses that could explain the behavior of the breakthrough curves of the tracer in this test design. Of all the possibilities (like sorption processes, unexpected tracer reactions, inhomogeneities in the aquifer, influence of the well design), we assume that ion exchange processes and density driven flow are the main reasons for the repeatedly observed anomaly. References: Hebig, K.H., Ito, N., Scheytt, T.J. & Marui, A. (2011). Hydraulic and hydrochemical characterization of deep coastal sedimentary basins by single-well Push-Pull tests. GSA Annual Meeting, 9-12 October 2011, Minneapolis, USA. Zeilfelder, S., Ito, N., Marui, A., Hebig, K. & Scheytt, T. (2012). Push-Pull-Test und Tracer-Test in einem tiefen Grundwasserleiter in Kameoka, Japan. Kurzfassung in: Liedl, R., Burghardt, D., Simon, E., Reimann, T. & Kaufmann-Knoke (Hg.). Grundwasserschutz und Grundwassernutzung. Tagung der Fachsektion Hydrogeologie in der DGG (FH-DGG). 16. - 20. Mai 2012, Dresden. Kurfassungen der Vorträge und Poster. Schriftenreihe der DGG, Heft 78, S. 192.

Benchtop-magnetic resonance imaging (BT-MRI) characterization of push-pull osmotic controlled release systems.

PubMed

Malaterre, Vincent; Metz, Hendrik; Ogorka, Joerg; Gurny, Robert; Loggia, Nicoletta; Mäder, Karsten

2009-01-05

The mechanism of drug release from push-pull osmotic systems (PPOS) has been investigated by Magnetic Resonance Imaging (MRI) using a new benchtop apparatus. The signal intensity profiles of both PPOS layers were monitored non-invasively over time to characterize the hydration and swelling kinetics. The drug release performance was well-correlated to the hydration kinetics. The results show that (i) hydration and swelling critically depend on the tablet core composition, (ii) high osmotic pressure developed by the push layer may lead to bypassing the drug layer and incomplete drug release and (iii) the hydration of both the drug and the push layers needs to be properly balanced to efficiently deliver the drug. MRI is therefore a powerful tool to get insights on the drug delivery mechanism of push-pull osmotic systems, which enable a more efficient optimization of such formulations.

Coupled transport, mixing and biogeochemical reactions in fractured media: experimental observations and modelling at the Ploemeur fractured rock observatory

NASA Astrophysics Data System (ADS)

Le Borgne, T.; Bochet, O.; Klepikova, M.; Kang, P. K.; Shakas, A.; Aquilina, L.; Dufresne, A.; Linde, N.; Dentz, M.; Bour, O.

2016-12-01

Transport processes in fractured media and associated reactions are governed by multiscale heterogeneity ranging from fracture wall roughness at small scale to broadly distributed fracture lengths at network scale. This strong disorder induces a variety of emerging phenomena, including flow channeling, anomalous transport and heat transfer, enhanced mixing and reactive hotspot development. These processes are generally difficult to isolate and monitor in the field because of the high degree of complexity and coupling between them. We report in situ experimental observations from the Ploemeur fractured rock observatory (http://hplus.ore.fr/en/ploemeur) that provide new insights on the dynamics of transport and reaction processes in fractured media. These include dipole and push pull tracer tests that allow understanding and modelling anomalous transport processes characterized by heavy-tailed residence time distributions (Kang et al. 2015), thermal push pull tests that show the existence of highly channeled flow with a strong control on fracture matrix exchanges (Klepikova et al. 2016) and time lapse hydrogeophysical monitoring of saline tracer tests that allow quantifying the distribution of transport length scales governing dispersion processes (Shakas et al. 2016). These transport processes are then shown to induce rapid oxygen delivery and mixing at depth leading to massive biofilm development (Bochet et al., in prep.). Hence, this presentation will attempt to link these observations made at different scales to quantify and model the coupling between flow channeling, non-Fickian transport, mixing and chemical reactions in fractured media. References: Bochet et al. Biofilm blooms driven by enhanced mixing in fractured rock, in prep. Klepikova et al. 2016, Heat as a tracer for understanding transport processes in fractured media: theory and field assessment from multi-scale thermal push-pull tracer tests, Water Resour. Res. 52Shakas et al. 2016, Hydrogeophysical characterization of transport processes in fractured rock by combining push-pull and single-hole ground penetrating radar experiments, Water Resour. Res. 52 Kang et al. 2015, Impact of velocity correlation and distribution on transport in fractured media : Field evidence and theoretical model, Water Resour. Res., 51

Push-Pull and Feedback Mechanisms Can Align Signaling System Outputs with Inputs.

PubMed

Andrews, Steven S; Peria, William J; Yu, Richard C; Colman-Lerner, Alejandro; Brent, Roger

2016-11-23

Many cell signaling systems, including the yeast pheromone response system, exhibit "dose-response alignment" (DoRA), in which output of one or more downstream steps closely matches the fraction of occupied receptors. DoRA can improve the fidelity of transmitted dose information. Here, we searched systematically for biochemical network topologies that produced DoRA. Most networks, including many containing feedback and feedforward loops, could not produce DoRA. However, networks including "push-pull" mechanisms, in which the active form of a signaling species stimulates downstream activity and the nominally inactive form reduces downstream activity, enabled perfect DoRA. Networks containing feedbacks enabled DoRA, but only if they also compared feedback to input and adjusted output to match. Our results establish push-pull as a non-feedback mechanism to align output with variable input and maximize information transfer in signaling systems. They also suggest genetic approaches to determine whether particular signaling systems use feedback or push-pull control. Copyright © 2016 Elsevier Inc. All rights reserved.

A demonstration of NIOSH push-pull ventilation criteria.

PubMed

Klein, M K

1987-03-01

This paper summarizes the results of a study performed on an actual chrome plating tank in order to validate criteria for push-pull ventilation systems developed by Huebener and Hughes at NIOSH. Validation of the criteria was made by taking area industrial hygiene samples for hexavalent and total chrome at ten locations around the plating tank. The sampling was performed during actual production runs or while the tank was operating with a dummy load. The sampling data are summarized. The data show that the push-pull system, operating at Huebener's criteria, could control emissions to below the current standards and guidelines. Conclusions and recommendations are included.

Anomalous transport in fracture networks: field scale experiments and modelling

NASA Astrophysics Data System (ADS)

Kang, P. K.; Le Borgne, T.; Bour, O.; Dentz, M.; Juanes, R.

2012-12-01

Anomalous transport is widely observed in different settings and scales of transport through porous and fractured geologic media. A common signature of anomalous transport is the late-time power law tailing in breakthrough curves (BTCs) during tracer tests. Various conceptual models of anomalous transport have been proposed, including multirate mass transfer, continuous time random walk, and stream tube models. Since different conceptual models can produce equally good fits to a single BTC, tracer test interpretation has been plagued with ambiguity. Here, we propose to resolve such ambiguity by analyzing BTCs obtained from both convergent and push-pull flow configurations at two different fracture planes. We conducted field tracer tests in a fractured granite formation close to Ploemeur, France. We observe that BTC tailing depends on the flow configuration and the injection fracture. Specifically the tailing disappears under push-pull geometry, and when we injected at a fracture with high flux (Figure 1). This indicates that for this fractured granite, BTC tailing is controlled by heterogeneous advection and not by matrix diffusion. To explain the change in tailing behavior for different flow configurations, we employ a simple lattice network model with heterogeneous conductivity distribution. The model assigns random conductivities to the fractures and solves the Darcy equation for an incompressible fluid, enforcing mass conservation at fracture intersections. The mass conservation constraint yields a correlated random flow through the fracture system. We investigate whether BTC tailing can be explained by the spatial distribution of preferential flow paths and stagnation zones, which is controlled by the conductivity variance and correlation length. By combining the results from the field tests and numerical modeling, we show that the reversibility of spreading is a key mechanism that needs to be captured. We also demonstrate the dominant role of the injection fracture on the tailing behavior: where we inject makes the difference in the tailing. Blue line is a BTC with injection into a slow velocity zone under convergent flow configuration. The late-time tailing observed for the convergent test diminished for push-pull experiment performed in the same zone(red line). Black line is a BTC with injection into a high velocity zone under convergent flow configuration. Insets: illustration of convergent and push-pull tracer tests using a double packer system.

Gravity Driven Universe: Energy from a Unified Field

NASA Astrophysics Data System (ADS)

Masters, Roy

2012-10-01

One way or another, whether push or pull, we know for sure that gravity is omnidirectional with identical mathematics. With PULL, gravity can be seen as as a property of matter. If so something is wrong. The Moon, lifting the tides twice-daily, should have fallen into orbital decay, with Earth having pulled it down eons ago. It is puzzling that physicists are not troubled by the fact that the Moon not only insists on forever lifting the tides, but, adding insult to injury, keeps moving it about 4 cm further away from Earth each year. Now if instead, we consider gravity as driven by an omnidirectional pressure--a PUSH force, another possibility arises. We can consider that it is mysteriously infusing energy into the Earth-Moon system, sustaining the Moon's orbit with the appearance of raising the tides and actually pushing it away from Earth. Here we can show push and pull, while being identical in their mathematics, have different outcomes. With push, gravity is a property of the universe. If this is true, then gravitation is flowing from an everlasting source, and the Earth/Moon system is one example of many other vacuum energy machines in the universe.

Phase inverter provides variable reference push-pull output

NASA Technical Reports Server (NTRS)

1966-01-01

Dual-transistor difference amplifier provides a push-pull output referenced to a dc potential which can be varied without affecting the signal levels. The amplifier is coupled with a feedback circuit which can vary the operating points of the transistors by equal amounts to provide the variable reference potentials.

The Four-Ball Gyro and Motorcycle Countersteering

ERIC Educational Resources Information Center

Galli, J. Ronald; Carroll, Bradley W.

2017-01-01

Most two-wheel motorcycle riders know that, at highway speeds, if you want to turn left you push on the "left" handlebar and pull on the "right" handlebar. This is called "countersteering." Countersteering is counterintuitive since pushing left and pulling right when the front wheel is not spinning would turn the…

Evaluation of Interhandle Distance During Pushing and Pulling of a Four-Caster Cart for Upper Limb Exertion.

PubMed

Ohnishi, Akihiro; Takanokura, Masato; Sugama, Atsushi

2016-09-01

This study examined the relationship between interhandle distances and upper limb exertion during simply pushing and pulling of a cart with four swivel wheels, defined by a roll box pallet (RBP) in a Japanese industrial standard. Six healthy young male participants were asked to push and pull an RBP at a distance of 5.2 m under six conditions corresponding to different interhandle distances (40 cm, 60 cm, and 80 cm) and weights (130 kg and 250 kg). The upper limb exertion was studied by shoulder abduction and flexion, and elbow flexion, as well as surface electromyogram (EMG) in shoulder extensor, and elbow flexor and extensor. Participants were required to provide subjective evaluations on operability after each trial. Subjective operability indicated that a narrower interhandle distance had a better operability for pushing. Interhandle distance was also related to upper limb exertion especially for pushing. A narrow interhandle distance caused smaller shoulder adduction but larger elbow flexion. The normalized EMG data revealed that muscular activity became smaller with a narrow interhandle distance in shoulder extensor. During the pulling task, elbow flexion was smaller at a narrow interhandle distance, although subjective operability and normalized EMG were not significantly varied. A wider interhandle distance, such as 80 cm, was not suitable in the forwardbackward movement of the RBP. Therefore, this study concluded that an interhandle distance of 40 cm would be suitable for pushing and pulling an RBP to protect the workers' hands against the risk of injury by installing inner handles.

Centrosome centering and decentering by microtubule network rearrangement

PubMed Central

Letort, Gaëlle; Nedelec, Francois; Blanchoin, Laurent; Théry, Manuel

2016-01-01

The centrosome is positioned at the cell center by pushing and pulling forces transmitted by microtubules (MTs). Centrosome decentering is often considered to result from asymmetric, cortical pulling forces exerted in particular by molecular motors on MTs and controlled by external cues affecting the cell cortex locally. Here we used numerical simulations to investigate the possibility that it could equally result from the redistribution of pushing forces due to a reorientation of MTs. We first showed that MT gliding along cell edges and pivoting around the centrosome regulate MT rearrangement and thereby direct the spatial distribution of pushing forces, whereas the number, dynamics, and stiffness of MTs determine the magnitude of these forces. By modulating these parameters, we identified different regimes, involving both pushing and pulling forces, characterized by robust centrosome centering, robust off-centering, or “reactive” positioning. In the last-named conditions, weak asymmetric cues can induce a misbalance of pushing and pulling forces, resulting in an abrupt transition from a centered to an off-centered position. Taken together, these results point to the central role played by the configuration of the MTs on the distribution of pushing forces that position the centrosome. We suggest that asymmetric external cues should not be seen as direct driver of centrosome decentering and cell polarization but instead as inducers of an effective reorganization of the MT network, fostering centrosome motion to the cell periphery. PMID:27440925

Report to the House and Senate Appropriations Committees: the safety of push-pull and multiple-unit locomotive passenger rail operations

DOT National Transportation Integrated Search

2006-06-30

This report contains the results of a study by the Federal Railroad Administration (FRA) on the safety of push-pull and multiple-unit (MU) locomotive passenger rail operations. The report addresses the following two questions: (1) Based on recent acc...

Photoinduced intramolecular charge transfer in a cross-conjugated push-pull enediyne: implications toward photoreaction.

PubMed

Singh, Anuja; Pati, Avik Kumar; Mishra, Ashok Kumar

2018-05-30

Push-pull organic fluorophores are important owing to their interesting optoelectronical properties. Here we report the photophysics of a new cross-conjugated push-pull enediynyl dye which belongs to an unexplored class of π-conjugated donor-acceptor systems. Two N,N-dimethylaniline moieties serve as donors and one pyrene ring functions as an acceptor via a common Y-shaped 'enediyne' bridge which facilitates the cross-electronic communication. The dye exhibits dual emission from locally excited (LE) and intramolecular charge transfer (ICT) states. While the LE emission is dominant in non-polar solvents, the ICT emission predominates in polar solvents. Time-resolved fluorescence decay experiments reveal a relatively shorter lifetime component (∼0.5-0.9 ns) belonging to an ICT state and a relatively longer lifetime species (∼1.6-2.8 ns) corresponding to the LE state. The strong ICT behavior of the dye is manifested through the huge red-shift (4166 cm-1) of the emission spectra from non-polar cyclohexane to polar N,N-dimethylformamide. In contrast to many small push-pull organic dyes, the LE and ICT states of the push-pull enediynyl dye follow the same excitation pathway. The dominant red-shifted ICT emission (∼550 nm) intensity of the dye in polar solvent decreases with a concomitant appearance of the blue-shifted LE emission (∼385 nm) upon prolonged exposure to photons. This opens up a new photophysical strategy of achieving high contrast two fluorescence color conversion from yellow to blue.

Development of radon-222 as a natural tracer for monitoring the remediation of NAPL contamination in the subsurface. 1998 annual progress report

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

Semprini, L.; Istok, J.

'The objective of this research is to develop a unique method of using naturally occurring radon-222 as a tracer for locating and quantitatively describing the presence of subsurface NAPL contamination. The research will evaluate using radon as an inexpensive, yet highly accurate, means of detecting NAPL contamination and assessing the effectiveness of NAPL remediation. Laboratory, field, and modeling studies are being performed to evaluate this technique, and to develop methods for its successful implementation in practice. This report summarizes work that has been accomplished after 1-year of a 3-year project. The research to date has included radon tracer tests inmore » physical aquifer models (PAMs) and field studies at Site 300 of the Lawrence Livermore National Laboratory, CA, and Site 100D at Hanford DOE Facility, WA. The PAM tests have evaluated the ability of radon as a tracer to monitor the remediation of TCE NAPL contamination using surfactant treatment, and oxidation with permanganate. The surfactant tests were performed in collaboration with Dr. Jack Istok and Dr. Jennifer Field and their EMSP project ``In-situ, Field-Scale Evaluation of Surfactant Enhanced DNAPL Recovery Using a Single-Well-Push-Pull Test.'''' This collaboration enabled the EMSP radon project to make rapid progress. The PAM surfactant tests were performed in a radial flow geometry to simulate the push-pull-method that is being developed for surfactant field tests. The radon tests were easily incorporated into these experiments, since they simply rely on measuring the natural radon present in the subsurface fluids. Two types of radon tests were performed: (1) static tests where radon was permitted to build-up to steady-state concentrations in the pore fluids and the groundwater concentrations were monitored, and (2) dynamic tests were the radon response during push-pull surfactant tests was measured. Both methods were found to be useful in determining how NAPL remediation was progressing.'« less

In situ Measurements of Dissolved Gas Dynamics and Root Uptake in the Wetland Rhizosphere

NASA Astrophysics Data System (ADS)

Reid, Matthew; Jaffe, Peter

2013-04-01

Anaerobic wetland soils are important natural sources of various atmospheric trace gases that are detrimental to the environment, including methane (CH4), nitrous oxide, elemental mercury (Hg°), and halomethanes. The balance between production and uptake in soils depends, in part, on mass transfer within the soil and between soil and the atmosphere. Observed volatilization rates of trace gases are highly variable and poorly described by models, however, so there is a clear need for new process measurements to clarify the rates of these transport mechanisms. Here we present results from mesocosm push-pull tests intended to quantify transport processes of dissolved gases in wetland sediments, with a focus on uptake by wetland plant roots and partitioning into trapped gas bubbles. This technique uses a suite of nonreactive volatile tracers to pinpoint transport mechanisms without the confounding influence of biochemical transformations. Mass balance approaches are used to determine transport kinetics, and a new analytical method to interpret dissolved gas push-pull test data is presented and compared to traditional analytical techniques. Results confirm the key role of vegetation in dramatically enhancing removal rates of dissolved gases from wetland soils. Root uptake is shown to be diffusion-limited and relative root uptake rates are modeled as an empirical function of molecular size. We use the porewater removal rates measured here to estimate potential volatilization fluxes of CH4, methyl chloride, and Hg° from wetlands vegetated with Typha latifolia and Scirpus acutus. The implementation of this new push-pull test methodology to field settings will be discussed.

Formative Assessment Probes: Pushes and Pulls

ERIC Educational Resources Information Center

Keeley, Page

2011-01-01

When the concept of force is first taught in the elementary curriculum, it is usually introduced as a push or a pull. The recently released "A Framework for K-12 Science Education" describes grade band endpoints for the Core Idea: Motion and Stability: Forces and Interactions (NRC 2011). It states that by the end of grade 2 students should know…

Fiber-optic push-pull sensor systems

NASA Technical Reports Server (NTRS)

Gardner, David L.; Brown, David A.; Garrett, Steven L.

1991-01-01

Fiber-optic push-pull sensors are those which exploit the intrinsically differential nature of an interferometer with concommitant benefits in common-mode rejection of undesired effects. Several fiber-optic accelerometer and hydrophone designs are described. Additionally, the recent development at the Naval Postgraduate School of a passive low-cost interferometric signal demodulator permits the development of economical fiber-optic sensor systems.

The push–pull tactic for mitigation of mountain pine beetle (Coleoptera: Curculionidae) damage in lodgepole and whitebark pines

Treesearch

Nancy E. Gillette; Constance J. Mehmel; Sylvia R. Mori; Jeffrey N. Webster; David L. Wood; Nadir Erbilgin; Donald R. Owen

2012-01-01

In an attempt to improve semiochemical-based treatments for protecting forest stands from bark beetle attack, we compared push-pull versus push-only tactics for protecting lodgepole pine (Pinus contorta Douglas ex Loudon) and whitebark pine (Pinus albicaulis Engelm.) stands from attack by mountain pine beetle (...

Pushed or Pulled? Exploring the Factors Underpinning Graduate Start-Ups and Non-Start-Ups

ERIC Educational Resources Information Center

Nabi, G.; Walmsley, A.; Holden, R.

2015-01-01

The study explores the nature and mixture of push--pull factors in the journey from higher education into graduate entrepreneurship. Using longitudinal data from 15 graduates of a British university, it compares graduates who started their own business with graduates that did not. Importantly, both groups had initially indicated a strong desire to…

Voices from the "Working Lives" Project: The Push-Pull of Work and Care

ERIC Educational Resources Information Center

Fehring, Heather; Herring, Katherine

2012-01-01

A recent policy direction in many OECD countries has been to increase workforce participation for women of childbearing age; a policy direction which seemingly runs counter to a need for improved work-life balance for women themselves. This article explores the impact of this somewhat contradictory "push-pull" of policy by examining some…

Fixing Affordability: An Approach for Advancing Federalism in the Modern Era. State-Federal Partnerships in Postsecondary Education

ERIC Educational Resources Information Center

Cooper, Michelle Asha

2016-01-01

There is a constant push and pull between state and the federal governments to find the right balance of federalism. By applying this "push-pull" framework to higher education, this brief looks at past policy interventions and how this framework can help to understand the free college movement.

Why People Choose to Teach in Urban Schools: The Case for a Push-Pull Factor Analysis

ERIC Educational Resources Information Center

Knell, Paul F.; Castro, Antonio J.

2014-01-01

This qualitative research study traces the motivations for teaching of 13 teacher candidates enrolled in an urban-based alternative certification program. After using a push-pull factor analysis, the data suggest that most participants left their previous careers due to financial shortcomings or work instability. As a result, these participants…

Push-pull quinoidal porphyrins.

PubMed

Smith, Martin J; Blake, Iain M; Clegg, William; Anderson, Harry L

2018-05-01

A family of push-pull quinoidal porphyrin monomers has been prepared from a meso-formyl porphyrin by bromination, thioacetal formation, palladium-catalyzed coupling with malononitrile and oxidation with DDQ. Attempts at extending this synthesis to a push-pull quinoidal/cumulenic porphyrin dimer were not successful. The crystal structures of the quinoidal porphyrins indicate that there is no significant contribution from singlet biradical or zwitterionic resonance forms. The crystal structure of an ethyne-linked porphyrin dimer shows that the torsion angle between the porphyrin units is only about 3°, in keeping with crystallographic results on related compounds, but contrasting with the torsion angle of about 35° predicted by computational studies. The free-base quinoidal porphyrin monomers form tightly π-stacked layer structures, despite their curved geometries and bulky aryl substituents.

Individual and institutional push and pull factors as predictors of retirement timing in Europe: A multilevel analysis.

PubMed

De Preter, Hanne; Van Looy, Dorien; Mortelmans, Dimitri

2013-12-01

The number of retired people in Europe has increased significantly in recent decades. It remains unclear, however, whether individuals are more likely to be pulled toward retirement by their expectations about life after retirement than they are to be pushed out of the labour market due to poor health or dislike of one's job. The fact that retirement timing differs rather considerably between European countries suggests that not only micro, but also macro push (i.e. labour market constraints) and pull (i.e. economic incentives) factors influence retirement decisions. This duality heightens the need to determine the influence of micro-level and macro-level push and pull indicators on the retirement timing of older workers (50+) in Europe. Results are obtained performing multilevel event history analysis using longitudinal micro data from the first (2004/05) and second (2006/07) waves of the Survey of Health, Ageing and Retirement in Europe and macro data derived from the Organisation for Economic Cooperation and Development (OECD) and Eurostat. The results indicate that at the individual level, older workers are pushed out due to health problems as well as being attracted towards retirement to spend time with their grandchildren. At the institutional level, financial incentives such as a high implicit tax on continued work and high expenditures on early exit schemes make retirement attractive, whereas the institutional push context is of lesser importance. © 2013.

Local ventilation solution for large, warm emission sources.

PubMed

Kulmala, Ilpo; Hynynen, Pasi; Welling, Irma; Säämänen, Arto

2007-01-01

In a foundry casting line, contaminants are released from a large area. Casting fumes include both volatile and particulate compounds. The volatile fraction contains hydrocarbons, whereas the particulate fraction mostly comprises a mixture of vaporized metal fumes. Casting fumes lower the air quality in foundries. The design of local ventilation for the casting area is a challenging task, because of the large casting area and convection plumes from warm moulds. A local ventilation solution for the mould casting area was designed and dimensioned with the aid of computational fluid dynamic (CFD) calculations. According to the calculations, the most efficient solution was a push-pull ventilation system. The prototype of the push-pull system was built and tested in actual operation at the foundry. The push flow was generated by a free plane jet that blew across the 10 m wide casting area towards an exhaust hood on the opposite side of the casting lines. The capture efficiency of the prototype was determined by the tracer gas method. The measured capture efficiencies with push jet varied between 40 and 80%, depending on the distance between the source and the exhaust. With the aid of the push flow, the average capture efficiency was increased from 40 (without jet) to 60%.

Anomalous Transport in Single-Well Push-Pull Tracer Tests

NASA Astrophysics Data System (ADS)

Chen, K.; Zhan, H.

2016-12-01

Single-Well Push-Pull (SWPP) tracer test was conducted to estimate the hydraulic and transport properties in a fractured aquifer at Newark basin. A common phenomenon observed for a set of SWPP tests with different incubation time is the heavy tailing of breakthrough curve (BTC) in pumping phase. A novel model with fractional-in-time and (or) -space was developed to interpret the anomalous transport behavior in SWPP tests. The fractal models, including fractional-in-time, fractional-in-space and fractional-in-time-and-space, were solved in radial coordinate using implicit Euler method. A semi-analytical solution of the mobile-immobile (MIM) model was derived as well for comparison purpose. It is found that the fractional-in-space and fractional-in-time-and-space models match the experimental data well. The BTC of the MIM model drops slower than that of the fractional-in-space model at the beginning of pumping and drops much faster at late time. The best match of fractional-in-space model with the experimental data demonstrates that the non-local transport in space plays an important role in SWPP tests conducted in fractured aquifers.

Proceedings of the Seventh Joint Magnetism and Magnetic Materials-Intermag Conference 6-9 January 1998 San Francisco, California Volume 83, Number 11, Part 2.

DTIC Science & Technology

1998-06-01

drying (surface tension tends to pull the oscillators to the substrate). To overcome this, a freeze- drying technique5 was successfully employed...left magnet in the 6 direc- tion, push and pull forces occur on the right magnet. When the right magnet is restricted to linear motion, the magnet...make the magnetic field intensity yielding the forces large, the iron yoke is fixed to the rotating magnet on the left side. The push- pull force

The "Push-Pull" Approach to Fast-Track Management Development: A Case Study in Scientific Publishing

ERIC Educational Resources Information Center

Fojt, Martin; Parkinson, Stephen; Peters, John; Sandelands, Eric

2008-01-01

Purpose: The purpose of this paper is to explore how a medium sized business has addressed what it has termed a "push-pull" method of management and organization development, based around an action learning approach. Design/methodology/approach: The paper sets out a methodology that other SMEs might look to replicate in their management and…

Business and Education as Push-Pull Processes: An Alliance of Philosophy and Practice.

ERIC Educational Resources Information Center

Arif, Mohammed; Smiley, Frederick M.; Kulonda, Dennis J.

2005-01-01

In the 1960s, the U.S. business community utilized the term "push/pull" to indicate whether or not industry should use the "one-size-fits all" or whether it should listen to consumers' needs and feedback as a system of producing and marketing products. As well, U.S. public education has become much more accountability-laden…

Effects of push/pull perfusion and ultrasonication on the extraction efficiencies of phthalate esters in sports drink samples using on-line hollow-fiber liquid-phase microextraction.

PubMed

Chao, Yu-Ying; Lee, Chien-Hung; Chien, Tzu-Yang; Shih, Yu-Hsuan; Lu, Yin-An; Kuo, Ting-Hsuan; Huang, Yeou-Lih

2013-08-28

In previous studies, we developed a process, on-line ultrasound-assisted push/pull perfusion hollow-fiber liquid-phase microextraction (UA-PPP-HF-LPME), combining the techniques of push/pull perfusion (PPP) and ultrasonication with hollow-fiber liquid-phase microextraction (HF-LPME), to achieve rapid extraction of acidic phenols from water samples. In this present study, we further evaluated three more-advanced and novel effects of PPP and ultrasonication on the extraction efficiencies of neutral high-molecular-weight phthalate esters (HPAEs) in sports drinks. First, we found that inner-fiber fluid leakage occurs only in push-only perfusion-based and pull-only perfusion-based HF-LPME, but not in the PPP mode. Second, we identified a significant negative interaction between ultrasonication and temperature. Third, we found that the extraction time of the newly proposed system could be shortened by more than 93%. From an investigation of the factors affecting UA-PPP-HF-LPME, we established optimal extraction conditions and achieved acceptable on-line enrichment factors of 92-146 for HPAEs with a sampling time of just 2 min.

Tectonic mode switches and the nature of orogenesis

NASA Astrophysics Data System (ADS)

Lister, Gordon; Forster, Marnie

2009-12-01

The birth and death of many mountain belts occurs in lithosphere that over-rides major subduction zones. Here the tectonic mode (shortening versus extension) can abruptly switch, even during continuous and otherwise smooth convergence. If the hinge line of the foundering slab rapidly retreats (i.e. rolls back), the foundering slab creates a gravitational potential well into which the orogen collapses. This motion, coupled with stress guides, can "pull" the orogen apart. A slowing of roll-back (or of hinge retreat) means that the subduction flexure may subsequently begin to be "pushed back" or be "pushed over" by the advancing orogen. The consequence of such changes in relative motion is that orogenic belts are affected by abrupt tectonic mode switches. The change from "push" to "pull" leads to a sudden change from horizontal extension to horizontal shortening, potentially throughout the entire mass of the orogenic lithosphere that over-rides the subducting slab. The sequencing of these tectonic mode switches affects the thermal evolution of the orogen, and thus fundamentally determines the nature of orogenesis. This insight led to us to our quite different views as to how orogens work. It is evident that orogens affected by abrupt "push-pull" mode switches are characterized by high-pressure metamorphism, whereas orogens affected by abrupt "pull-push" mode switches are characterized by high-temperature metamorphism, magmatism and anatexis.

The Effects of Direction of Exertion, Path, and Load Placement in Nursing Cart Pushing and Pulling Tasks: An Electromyographical Study.

PubMed

Kao, Huei Chu; Lin, Chiuhsiang Joe; Lee, Yung Hui; Chen, Su Huang

2015-01-01

The purpose of this study was to explore the effects of direction of exertion (DOE) (pushing, pulling), path (walking in a straight line, turning left, walking uphill), and load placement (LP) (the 18 blocks were indicated by X, Y and Z axis; there were 3 levels on the X axis, 2 levels on the Y axis, and 3 levels on the Z axis) on muscle activity and ratings of perceived exertion in nursing cart pushing and pulling tasks. Ten participants who were female students and not experienced nurses were recruited to participate in the experiment. Each participant performed 108 experimental trials in the study, consisting of 2 directions of exertion (push and pull), 3 paths, and 18 load placements (indicated by X, Y and Z axes). A 23kg load was placed into one load placement. The dependent variables were electromyographic (EMG) data of four muscles collected bilaterally as follows: Left (L) and right (R) trapezius (TR), flexor digitorum superficialis (FDS), extensor digitorum (ED), and erector spinae (ES) and subjective ratings of perceived exertion (RPE). Split-split-plot ANOVA was conducted to analyze significant differences between DOE, path, and LP in the EMG and RPE data. Pulling cart tasks produced a significantly higher activation of the muscles (RTR:54.4%, LTR:50.3%, LFDS:57.0%, LED:63.4%, RES:40.7%, LES:36.7%) than pushing cart tasks (RTR:42.4%, LTR:35.1%, LFDS:32.3%, LED:55.1%, RES:33.3%, LES:32.1%). A significantly greater perceived exertion was found in pulling cart tasks than pushing cart tasks. Significantly higher activation of all muscles and perceived exertion were observed for walking uphill than walking in a straight line and turning left. Significantly lower muscle activity of all muscles and subject ratings were observed for the central position on the X axis, the bottom position on the Y axis, and the posterior position on the Z axis. These findings suggest that nursing staff should adopt forward pushing when moving a nursing cart, instead of backward pulling, and that uphill paths should be avoided in the design of work environments. In terms of distribution of the load in a nursing cart, heavier materials should be positioned at bottom of the cabinet, centered on the horizontal plane and close to the handle, to reduce the physical load of the nursing staff.

The Effects of Direction of Exertion, Path, and Load Placement in Nursing Cart Pushing and Pulling Tasks: An Electromyographical Study

PubMed Central

Kao, Huei Chu; Lin, Chiuhsiang Joe; Lee, Yung Hui; Chen, Su Huang

2015-01-01

The purpose of this study was to explore the effects of direction of exertion (DOE) (pushing, pulling), path (walking in a straight line, turning left, walking uphill), and load placement (LP) (the 18 blocks were indicated by X, Y and Z axis; there were 3 levels on the X axis, 2 levels on the Y axis, and 3 levels on the Z axis) on muscle activity and ratings of perceived exertion in nursing cart pushing and pulling tasks. Ten participants who were female students and not experienced nurses were recruited to participate in the experiment. Each participant performed 108 experimental trials in the study, consisting of 2 directions of exertion (push and pull), 3 paths, and 18 load placements (indicated by X, Y and Z axes). A 23kg load was placed into one load placement. The dependent variables were electromyographic (EMG) data of four muscles collected bilaterally as follows: Left (L) and right (R) trapezius (TR), flexor digitorum superficialis (FDS), extensor digitorum (ED), and erector spinae (ES) and subjective ratings of perceived exertion (RPE). Split-split-plot ANOVA was conducted to analyze significant differences between DOE, path, and LP in the EMG and RPE data. Pulling cart tasks produced a significantly higher activation of the muscles (RTR:54.4%, LTR:50.3%, LFDS:57.0%, LED:63.4%, RES:40.7%, LES:36.7%) than pushing cart tasks (RTR:42.4%, LTR:35.1%, LFDS:32.3%, LED:55.1%, RES:33.3%, LES:32.1%). A significantly greater perceived exertion was found in pulling cart tasks than pushing cart tasks. Significantly higher activation of all muscles and perceived exertion were observed for walking uphill than walking in a straight line and turning left. Significantly lower muscle activity of all muscles and subject ratings were observed for the central position on the X axis, the bottom position on the Y axis, and the posterior position on the Z axis. These findings suggest that nursing staff should adopt forward pushing when moving a nursing cart, instead of backward pulling, and that uphill paths should be avoided in the design of work environments. In terms of distribution of the load in a nursing cart, heavier materials should be positioned at bottom of the cabinet, centered on the horizontal plane and close to the handle, to reduce the physical load of the nursing staff. PMID:26485039

Effect of a powered drive on pushing and pulling forces when transporting bariatric hospital beds.

PubMed

Wiggermann, Neal

2017-01-01

Powered drives designed to assist with moving hospital beds are commercially available but no studies have evaluated whether they reduce the push and pull forces likely contributing to injury in caregivers. This study measured hand forces of 10 caregivers maneuvering a manual and powered bariatric bed through simulated hospital environments (hallway, elevator, and ramp). Peak push and pull forces exceeded previously established psychophysical limits for all activities with the manual bed. For the powered bed, peak forces were significantly (p < 0.05) lower for all tasks, and below psychophysical limits. Powered drive reduced peak forces between 38% (maneuvering into elevator) and 94% (descending ramp). Powered drive also reduced stopping distance by 55%. When maneuvering, the integral of hand force was 34% lower with powered drive, but average forces during straight-line pushing did not differ between beds. Powered drive may reduce the risk of injury or the number of caregivers needed for transport. Copyright © 2016 Elsevier Ltd. All rights reserved.

An Evaluation of Two English Language Learner (ELL) Instructional Models at School District ABC: Pull-In and Push-Out

ERIC Educational Resources Information Center

Lloyd, Sonya LaShawn

2014-01-01

Providing academic assistance to English Language Learners (ELLs) is varied and often ineffective. The purpose of this causal-comparative study was to determine if there was a relationship between 9th grade students' performance on the High School Graduation Exam (HSGE) in reading and language and the Push-in and Pull-out models of instruction.…

The compression and expansion waves of the forward and backward flows: an in-vitro arterial model.

PubMed

Feng, J; Khir, A W

2008-05-01

Although the propagation of arterial waves of forward flows has been studied before, that of backward flows has not been thoroughly investigated. The aim of this research is to investigate the propagation of the compression and expansion waves of backward flows in terms of wave speed and dissipation, in flexible tubes. The aim is also to compare the propagation of these waves with those of forward flows. A piston pump generated a flow waveform in the shape of approximately half-sinusoid, in flexible tubes (12 mm and 16 mm diameter). The pump produced flow in either the forward or the backward direction by moving the piston forward, in a 'pushing action' or backward, in a 'pulling action', using a graphite brushes d.c. motor. Pressure and flow were measured at intervals of 5 cm along each tube and wave speed was determined using the PU-loop method. The simultaneous measurements of diameter were also taken at the same position of the pressure and flow in the 16 mm tube. Wave intensity analysis was used to determine the magnitude of the pressure and velocity waveforms and wave intensity in the forward and backward directions. Under the same initial experimental conditions, wave speed was higher during the pulling action (backward flow) than during the pushing action (forward flow). The amplitudes of pressure and velocity in the pulling action were significantly higher than those in the pushing action. The tube diameter was approximately 20 per cent smaller in the pulling action than in the pushing action in the 16 mm tube. The compression and expansion waves resulting from the pushing and pulling actions dissipated exponentially along the travelling distance, and their dissipation was greater in the smaller than in the larger tubes. Local wave speed in flexible tubes is flow direction- and wave nature-dependent and is greater with expansion than with compression waves. Wave dissipation has an inverse relationship with the vessel diameter, and dissipation of the expansion wave of the pulling action was greater than that of the pushing action.

Research on Precision Tracking on Fast Steering Mirror and Control Strategy

NASA Astrophysics Data System (ADS)

Di, Lin; Yi-ming, Wu; Fan, Zhu

2018-01-01

Fast steering mirror is a device used for controlling the beam direction precisely. Due to the short travel of the push-pull FSM, a compound fast steering mirror system driven by both limited-angle voice coil motor and push-pull FSM together is proposed. In the compound FSM system, limited-angle voice coil motor quickly swings at wide angle, while the push-pull FSM do high frequency movement in a small range, which provides the system with the high bandwidth and long travel. In the control strategy, the method of combining feed-forward control in Kalman filtering with auto-disturbance rejection control is used to improve trajectory tracking accuracy. The simulation result shows that tracking accuracy measured by the compound method can be improved by more than 5 times than that of the conventional PID.

Finding the Cell Center by a Balance of Dynein and Myosin Pulling and Microtubule Pushing: A Computational Study

PubMed Central

Zhu, Jie; Burakov, Anton; Rodionov, Vladimir

2010-01-01

The centrosome position in many types of interphase cells is actively maintained in the cell center. Our previous work indicated that the centrosome is kept at the center by pulling force generated by dynein and actin flow produced by myosin contraction and that an unidentified factor that depends on microtubule dynamics destabilizes position of the centrosome. Here, we use modeling to simulate the centrosome positioning based on the idea that the balance of three forces—dyneins pulling along microtubule length, myosin-powered centripetal drag, and microtubules pushing on organelles—is responsible for the centrosome displacement. By comparing numerical predictions with centrosome behavior in wild-type and perturbed interphase cells, we rule out several plausible hypotheses about the nature of the microtubule-based force. We conclude that strong dynein- and weaker myosin-generated forces pull the microtubules inward competing with microtubule plus-ends pushing the microtubule aster outward and that the balance of these forces positions the centrosome at the cell center. The model also predicts that kinesin action could be another outward-pushing force. Simulations demonstrate that the force-balance centering mechanism is robust yet versatile. We use the experimental observations to reverse engineer the characteristic forces and centrosome mobility. PMID:20980619

Human Body Mechanics of Pushing and Pulling: Analyzing the Factors of Task-related Strain on the Musculoskeletal System.

PubMed

Argubi-Wollesen, Andreas; Wollesen, Bettina; Leitner, Martin; Mattes, Klaus

2017-03-01

The purpose of this review is to name and describe the important factors of musculoskeletal strain originating from pushing and pulling tasks such as cart handling that are commonly found in industrial contexts. A literature database search was performed using the research platform Web of Science. For a study to be included in this review differences in measured or calculated strain had to be investigated with regard to: (1) cart weight/ load; (2) handle position and design; (3) exerted forces; (4) handling task (push and pull); or (5) task experience. Thirteen studies met the inclusion criteria and proved to be of adequate methodological quality by the standards of the Alberta Heritage Foundation for Medical Research. External load or cart weight proved to be the most influential factor of strain. The ideal handle positions ranged from hip to shoulder height and were dependent on the strain factor that was focused on as well as the handling task. Furthermore, task experience and subsequently handling technique were also key to reducing strain. Workplace settings that regularly involve pushing and pulling should be checked for potential improvements with regards to lower weight of the loaded handling device, handle design, and good practice guidelines to further reduce musculoskeletal disease prevalence.

Finding the cell center by a balance of dynein and myosin pulling and microtubule pushing: a computational study.

PubMed

Zhu, Jie; Burakov, Anton; Rodionov, Vladimir; Mogilner, Alex

2010-12-01

The centrosome position in many types of interphase cells is actively maintained in the cell center. Our previous work indicated that the centrosome is kept at the center by pulling force generated by dynein and actin flow produced by myosin contraction and that an unidentified factor that depends on microtubule dynamics destabilizes position of the centrosome. Here, we use modeling to simulate the centrosome positioning based on the idea that the balance of three forces-dyneins pulling along microtubule length, myosin-powered centripetal drag, and microtubules pushing on organelles-is responsible for the centrosome displacement. By comparing numerical predictions with centrosome behavior in wild-type and perturbed interphase cells, we rule out several plausible hypotheses about the nature of the microtubule-based force. We conclude that strong dynein- and weaker myosin-generated forces pull the microtubules inward competing with microtubule plus-ends pushing the microtubule aster outward and that the balance of these forces positions the centrosome at the cell center. The model also predicts that kinesin action could be another outward-pushing force. Simulations demonstrate that the force-balance centering mechanism is robust yet versatile. We use the experimental observations to reverse engineer the characteristic forces and centrosome mobility.

Pulled Motzkin paths

NASA Astrophysics Data System (ADS)

Janse van Rensburg, E. J.

2010-08-01

In this paper the models of pulled Dyck paths in Janse van Rensburg (2010 J. Phys. A: Math. Theor. 43 215001) are generalized to pulled Motzkin path models. The generating functions of pulled Motzkin paths are determined in terms of series over trinomial coefficients and the elastic response of a Motzkin path pulled at its endpoint (see Orlandini and Whittington (2004 J. Phys. A: Math. Gen. 37 5305-14)) is shown to be R(f) = 0 for forces pushing the endpoint toward the adsorbing line and R(f) = f(1 + 2cosh f))/(2sinh f) → f as f → ∞, for forces pulling the path away from the X-axis. In addition, the elastic response of a Motzkin path pulled at its midpoint is shown to be R(f) = 0 for forces pushing the midpoint toward the adsorbing line and R(f) = f(1 + 2cosh (f/2))/sinh (f/2) → 2f as f → ∞, for forces pulling the path away from the X-axis. Formal combinatorial identities arising from pulled Motzkin path models are also presented. These identities are the generalization of combinatorial identities obtained in directed paths models to their natural trinomial counterparts.

Upper Body Strength. Helping Kids Win the Battle.

ERIC Educational Resources Information Center

Rupnow, Allan

1985-01-01

A sedentary lifestyle, along with program cutbacks and changes in teaching emphasis, have led to lower scores every year on tests of upper body strength of elementary school children. Pulling, pushing and hanging activities are described, and a yearly program of fitness activities is suggested. (MT)

The great carbon push-pull: where science is pushing and policy is pulling the official forest carbon inventory of the US

Treesearch

C.W. Woodall; G.M. Domke; J. Coulston; M.B. Russell; J.A. Smith; C.H. Perry; S. Healey; A. Gray

2015-01-01

A national system of field inventory plots (FIA) is the primary data source for the annual assessment of US forest carbon (C) stocks and stock-change to meet reporting requirements under the United Nations Framework Convention on Climate Change (UNFCCC). The inventory data and their role in national carbon reporting continue to evolve. The framework of the previous C...

Push-pull switching power amplifier

NASA Technical Reports Server (NTRS)

Cuk, Slobodan M. (Inventor)

1980-01-01

A true push-pull switching power amplifier is disclosed utilizing two dc-to-dc converters. Each converter is comprised of two inductances, one inductance in series with a DC source and the other inductor in series with the output load, and an electrical energy transferring device with storage capability, namely storage capacitance, with suitable switching means between the inductances to obtain DC level conversion, where the switching means allows bidirectional current (and power) flow, and the switching means of one dc-to-dc converter is driven by the complement of a square-wave switching signal for the other dc-to-dc converter for true push-pull operation. For reduction of current ripple, the inductances in each of the two converters may be coupled, and with proper design of the coupling, the ripple can be reduced to zero at either the input or the output, but preferably the output.

Challenges And Concepts for Design of An Interaction Region With Push-Pull Arrangement of Detectors - An Interface Document

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

Parker, B.; /Brookhaven; Herve, Alain

2011-10-14

Two experimental detectors working in a push-pull mode has been considered for the Interaction Region of the International Linear Collider. The push-pull mode of operation sets specific requirements and challenges for many systems of detector and machine, in particular for the IR magnets, for the cryogenics and alignment system, for beamline shielding, for detector design and overall integration, and so on. These challenges and the identified conceptual solutions discussed in the paper intend to form a draft of the Interface Document which will be developed further in the nearest future. The authors of the present paper include the organizers andmore » conveners of working groups of the workshop on engineering design of interaction region IRENG07, the leaders of the IR Integration within Global Design Effort Beam Delivery System, and the representatives from each detector concept submitting the Letters Of Intent.« less

Theoretical modeling and experimental study of dielectric loss of the multi-push-pull mode magnetoelectric laminate composites

NASA Astrophysics Data System (ADS)

Xu, Bingbing; Ma, Jiashuai; Fang, Cong; Yao, Meng; Di, Wenning; Li, Xiaobing; Luo, Haosu

2018-02-01

In this work, we establish a dielectric loss model for multi-push-pull mode ME laminate composites. It deduces that the total dielectric loss of the ME composites equals the linear average of the dielectric loss of piezoelectric plate and epoxy resin. But further analysis of this model has indicated that we can ignore the dielectric loss of epoxy resin. To verify this model, we use three kinds of epoxy resin with different dielectric loss to fabricate multi-push-pull mode PMNT/Metglas ME laminate composites respectively. It turns out that the different kinds of epoxy resin have little influence on the total dielectric loss, capacitance and piezoelectricity of the composites, which demonstrates that our model conforms to the practical case. Therefore, we can pay more attention to the mechanical properties of epoxy resin rather than its dielectric loss on fabricating the ME laminate composites.

High-Cycle, Push-Pull Fatigue Fracture Behavior of High-C, Si-Al-Rich Nanostructured Bainite Steel.

PubMed

Zhao, Jing; Ji, Honghong; Wang, Tiansheng

2017-12-29

The high-cycle, push-pull fatigue fracture behavior of high-C, Si-Al-rich nanostructured bainitic steel was studied through the measurement of fatigue limits, a morphology examination and phase composition analysis of the fatigue fracture surface, as well as fractography of the fatigue crack propagation. The results demonstrated that the push-pull fatigue limits at 10⁷ cycles were estimated as 710-889 MPa, for the samples isothermally transformed at the temperature range of 220-260 °C through data extrapolation, measured under the maximum cycle number of 10⁵. Both the interior inclusion and the sample surface constituted the fatigue crack origins. During the fatigue crack propagation, a high amount of secondary cracks were formed in almost parallel arrangements. The apparent plastic deformation occurred in the fracture surface layer, which induced approximately all retained austenite to transform into martensite.

Push-you-pull-you: the boundaried self in close relationships.

PubMed

Rempel, John K; Burris, Christopher T

2006-02-01

Based on Amoebic Self Theory, the authors propose that the salience of different threats to the self affects the extent to which an intimate relationship partner is pushed away (excluded) or pulled closer (included). When social threat is salient among persons in relationships, it is hypothesized that partners will attempt to defuse the resulting sense of interpersonal vulnerability: offending partners may be pushed away, whereas offenders themselves may draw closer. When spatial-symbolic threat is salient and the relationship's capacity to function as an identity marker is jeopardized, it is hypothesized that the partner--regardless of his or her role--will be pulled closer to maintain the perception that the relationship is secure. Self-report responses to hypothetical scenarios and perceptions of behaviors during a role-play were generally consistent with these hypotheses, suggesting that both an intimate partner and the relationship with that partner can be incorporated into the self.

Dynamic aspects of voluntary turnover: an integrated approach to curvilinearity in the performance-turnover relationship.

PubMed

Becker, William J; Cropanzano, Russell

2011-03-01

Previous research pertaining to job performance and voluntary turnover has been guided by 2 distinct theoretical perspectives. First, the push-pull model proposes that there is a quadratic or curvilinear relationship existing between these 2 variables. Second, the unfolding model of turnover posits that turnover is a dynamic process and that a downward performance change may increase the likelihood of organizational separation. Drawing on decision theory, we propose and test an integrative framework. This approach incorporates both of these earlier models. Specifically, we argue that individuals are most likely to voluntarily exit when they are below-average performers who are also experiencing a downward performance change. Furthermore, the interaction between this downward change and performance partially accounts for the curvilinear relationship proposed by the push-pull model. Findings from a longitudinal field study supported this integrative theory. PsycINFO Database Record (c) 2011 APA, all rights reserved.

The influence of bone damage on press-fit mechanics.

PubMed

Bishop, Nicholas E; Höhn, Jan-Christian; Rothstock, Stephan; Damm, Niklas B; Morlock, Michael M

2014-04-11

Press-fitting is used to anchor uncemented implants in bone. It relies in part on friction resistance to relative motion at the implant-bone interface to allow bone ingrowth and long-term stability. Frictional shear capacity is related to the interference fit of the implant and the roughness of its surface. It was hypothesised here that a rough implant could generate trabecular bone damage during implantation, which would reduce its stability. A device was constructed to simulate implantation by displacement of angled platens with varying surface finishes (polished, beaded and flaked) onto the surface of an embedded trabecular bone cube, to different nominal interferences. Push-in (implantation) and Pull-out forces were measured and micro-CT scans were made before and after testing to assess permanent bone deformation. Depth of permanent trabecular bone deformation ('damage'), Pull-out force and Radial force all increased with implantation displacement and with implantation force, for all surface roughnesses. The proposed hypothesis was rejected, since primary stability did not decrease with trabecular bone damage. In fact, Pull-out force linearly increased with push-in force, independently of trabecular bone damage or implant surface. This similar behaviour for the different surfaces might be explained by the compaction of bone into the surfaces during push-in so that Pull-out resistance is governed by bone-on-bone, rather than implant surface-on-bone friction. The data suggest that maximum stability is achieved for the maximum implantation force possible (regardless of trabecular bone damage or surface roughness), but this must be limited to prevent periprosthetic cortical bone fracture, patient damage and component malpositioning. Copyright © 2014 Elsevier Ltd. All rights reserved.

Microcatheter entrapment retrieval from Onyx embolization in brain arteriovenous malformations: A technical note

PubMed Central

Grigorian, Arthur A

2015-01-01

Objective Many techniques have been use for retrieval of an entrapped microcatheter during Onyx (eV3 Neurovascular) embolization of brain arteriovenous malformations (BAVMs). We report our technique that we term “pull-push-pull” that can be utilized as first management in retrieving the microcatheter. Method We analyzed a total of 37 patients that underwent BAVM embolization with either Onyx 18 or 34 at our institution. Standard embolization techniques were utilized with the use of Marathon (eV3 Neurovascular) microcatheter. When difficulty in retrieving the microcatheter arose, we used the “pull-push-pull” technique. The technique comprises the eV3 protocol of retraction. In addition, the microcatheter is stretched causing the Onyx cast to stretch in its inner core, creating a more thorough cohesive property amongst the Onyx mixture. Then the microcatheter is pushed back and to its point of embolization origin. Afterwards, retraction of the microcatheter is enabled as it can be easily dislodged from the cast. Multiple attempts can be repeated as needed. Result and discussion We had three patients that had difficulty with removal of microcatheter (8.1%). Utilization of the “pull-push-pull” technique was used on two of those patients. No neurological complication was observed with our technique. We believe the cohesive property of Onyx solution helps in the retrieval of the catheter by our method and technique. Conclusion We believe the “pull-push-pull” can be utilized and be an additional technique before attempting other catheter retrieval techniques in Onyx BAVM embolization. PMID:26232252

Interpretation of single-well push-pull spikings conducted in deep crystalline formations (Soultz-s.-F. in the Upper Rhine Graben, and KTB-VB at the German site of ICDP)

NASA Astrophysics Data System (ADS)

Ghergut, J.; Sauter, M.; Behrens, H.; (Steffen) Fischer, S.; (Steffi) Fischer, S.; Licha, T.; Nottebohm, M.

2009-04-01

Two somewhat contrasting model approaches are presented, both aimed at interpreting long-term return signals from tracer push-pull tests conducted at single wells penetrating increased-permeability features in crystalline rock, about 4 km deep. The general idea is that single-well tracer push-pull tests, owing to the flow-field reversal, should provide privileged access to advection-independent parameters of solute transport, like the density of fluid-rock contact surface areas (Sauter et al., 2002). The latter is equivalent to the heat exchange area for a liquid-based geothermal system. At the geothermal site of Soultz-sous-Forêts in the Upper Rhine Graben, the French BRGM, in cooperation with EGI Utah and other partners, conducted a comprehensive tracer testing programme, whose results were presented in detail by Sanjuan et al. (2004, 2006), Rose et al. (2006). Of these results, we pick the tracer return signals detected during post-stimulation backflow periods at borehole GPK-2 between 2000 and 2002 (as published by Sanjuan et al., 2004) and attempt to interpret them in terms of a single-well injection-withdrawal sequence. Two chemically dissimilar organic tracers have been used by BRGM; however the difference between their return signals seems not significant enough to allow quantifying fluid-rock contact surfaces from this difference alone (additional / a priori information on coefficients of solute exchange across these surfaces would be required). Instead, the tracer return signals enable characterizing the nature of solute exchange processes within the spiked volume of the assumed fractured-porous formation (highly altered crystalline rock). At least one rapid-exchange (E-7 / d), slightly dispersive (Pe~12) component and one moderate-exchange (2E-8 / d), less dispersive (Pe~20) component appear to act within few hundred metres and, respectively, within at least 1 km radial distance from the borehole. - An alternative component of extremely fast exchange (increase of solute exchange fluxes by factor E+5) can as well reproduce the available data, but is physically implausible. For a reliable determination of heat exchange areas at geothermally relevant space scales, additional tracer testings (including heat backflow tests) would be required. At the German site of ICDP (Intl. Continental Scientific Drilling Program, with 'Kontinentale Tiefbohrung' at Windischeschenbach in NE Bavaria), a sequence of multi-tracer push-pull tests was conducted by the Göttingen Group between 2004 and 2006 at the pilot hole (KTB-VB) in hydraulically depleted, stimulated and post-stimulated states (following a long-term pumping test, and massive injection tests, respectively). Here, the spiking design was such that significant differences occurred between the signals of various simultaneously-injected tracers, enabling - at least theoretically - to quantify fracture densities; furthermore, the differences between solute and heat backflow signals produced under different hydraulic regimes can be used to characterize hydro-thermo-mechanical processes induced by massive cold-water injection. Both spiking-derived informations are relevant to a future geothermal project at this site. References: - P. E. Rose, M. Mella, J. McCulloch (2006) A Comparison of Hydraulic Stimulation Experiments at the Soultz/France and Coso/California Engineered Geothermal Systems. Stanford University, SGP-TR-179. - B. Sanjuan, P. Rose, J.-C. Foucher, M. Brach, G. Braibant (2004) Tracer testing at Soultz-sous-Forêts (France) using Na-benzoate, 1,5- and 2,7-napththalene disulfonate. Stanford University, SGP-TR-175. - B. Sanjuan, J.-L. Pinault, P. Rose, A. Gérard, M. Brach, G. Braibant, C. Crouzet, J.-C. Foucher, A. Gautier, S. Touzelet (2006) Tracer testing of the geothermal heat exchanger at Soultz-sous-Forêts (France) between 2000 and 2005. Geothermics, 35, 622-653. - M. Sauter, et al. (2002) Tracer push-pull experiment at the deep borehole Urach-3. Report, University of Göttingen.

L4-L5 compression and anterior/posterior joint shear forces in cabin attendants during the initial push/pull actions of airplane meal carts.

PubMed

Sandfeld, Jesper; Rosgaard, Christian; Jensen, Bente Rona

2014-07-01

The aim of the present study was to assess the acute low back load of cabin attendants during cart handling and to identify working situations which present the highest strain on the worker. In a setup, 17 cabin attendants (ten females and seven males) pushed, pulled and turned a 20 kg standard meal cart (L: 0.5m × W: 0.3 m × H: 0.92 m) loaded with extra 20 kg and 40 kg, respectively on two different surfaces (carpet and linoleum) and at three floor inclinations (-2°, 0° and +2°). Two force transducers were mounted as handles. Two-dimensional movement analysis was performed and a 4D WATBAK modelling tool was used to calculate the acute L4-L5 load. No working situations created loads greater than the accepted values for single exertions, however compression and anterior/posterior shear forces during pulling and turning were much higher when compared with pushing. There were significant effects of handling the cart on different floor types, at the varying inclinations and with different cart weights. Additionally, when external forces were reduced, the cabin attendants did not decrease push/pull force proportionally and thus the L4-L5 load did not decrease as much as expected. Copyright © 2014 Elsevier Ltd and The Ergonomics Society. All rights reserved.

Enhanced characterization of faults and fractures at EGS sites by CO2 injection coupled with active seismic monitoring, pressure-transient testing, and well logging

NASA Astrophysics Data System (ADS)

Oldenburg, C. M.; Daley, T. M.; Borgia, A.; Zhang, R.; Doughty, C.; Jung, Y.; Altundas, B.; Chugunov, N.; Ramakrishnan, T. S.

2016-12-01

Faults and fractures in geothermal systems are difficult to image and characterize because they are nearly indistinguishable from host rock using traditional seismic and well-logging tools. We are investigating the use of CO2 injection and production (push-pull) in faults and fractures for contrast enhancement for better characterization by active seismic, well logging, and push-pull pressure transient analysis. Our approach consists of numerical simulation and feasibility assessment using conceptual models of potential enhanced geothermal system (EGS) sites such as Brady's Hot Spring and others. Faults in the deep subsurface typically have associated damage and gouge zones that provide a larger volume for uptake of CO2 than the slip plane alone. CO2 injected for push-pull well testing has a preference for flowing in the fault and fractures because CO2 is non-wetting relative to water and the permeability of open fractures and fault gouge is much higher than matrix. We are carrying out numerical simulations of injection and withdrawal of CO2 using TOUGH2/ECO2N. Simulations show that CO2 flows into the slip plane and gouge and damage zones and is driven upward by buoyancy during the push cycle over day-long time scales. Recovery of CO2 during the pull cycle is limited because of buoyancy effects. We then use the CO2 saturation field simulated by TOUGH2 in our anisotropic finite difference code from SPICE-with modifications for fracture compliance-that we use to model elastic wave propagation. Results show time-lapse differences in seismic response using a surface source. Results suggest that CO2 can be best imaged using time-lapse differencing of the P-wave and P-to-S-wave scattering in a vertical seismic profile (VSP) configuration. Wireline well-logging tools that measure electrical conductivity show promise as another means to detect and image the CO2-filled fracture near the injection well and potential monitoring well(s), especially if a saline-water pre-flush is carried out to enhance conductivity contrast. Pressure-transient analysis is also carried out to further constrain fault zone characteristics. These multiple complementary characterization approaches are being used to develop working models of fault and fracture zone characteristics relevant to EGS energy recovery.

Automated multi-plug filtration cleanup for liquid chromatographic-tandem mass spectrometric pesticide multi-residue analysis in representative crop commodities.

PubMed

Qin, Yuhong; Zhang, Jingru; Zhang, Yuan; Li, Fangbing; Han, Yongtao; Zou, Nan; Xu, Haowei; Qian, Meiyuan; Pan, Canping

2016-09-02

An automated multi-plug filtration cleanup (m-PFC) method on modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) extracts was developed. The automatic device was aimed to reduce labor-consuming manual operation workload in the cleanup steps. It could control the volume and the speed of pulling and pushing cycles accurately. In this work, m-PFC was based on multi-walled carbon nanotubes (MWCNTs) mixed with other sorbents and anhydrous magnesium sulfate (MgSO4) in a packed tip for analysis of pesticide multi-residues in crop commodities followed by liquid chromatography with tandem mass spectrometric (LC-MS/MS) detection. It was validated by analyzing 25 pesticides in six representative matrices spiked at two concentration levels of 10 and 100μg/kg. Salts, sorbents, m-PFC procedure, automated pulling and pushing volume, automated pulling speed, and pushing speed for each matrix were optimized. After optimization, two general automated m-PFC methods were introduced to relatively simple (apple, citrus fruit, peanut) and relatively complex (spinach, leek, green tea) matrices. Spike recoveries were within 83 and 108% and 1-14% RSD for most analytes in the tested matrices. Matrix-matched calibrations were performed with the coefficients of determination >0.997 between concentration levels of 10 and 1000μg/kg. The developed method was successfully applied to the determination of pesticide residues in market samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Push pull microfluidics on a multi-level 3D CD.

PubMed

Thio, Tzer Hwai Gilbert; Ibrahim, Fatimah; Al-Faqheri, Wisam; Moebius, Jacob; Khalid, Noor Sakinah; Soin, Norhayati; Kahar, Maria Kahar Bador Abdul; Madou, Marc

2013-08-21

A technique known as thermo-pneumatic (TP) pumping is used to pump fluids on a microfluidic compact disc (CD) back towards the CD center against the centrifugal force that pushes liquids from the center to the perimeter of the disc. Trapped air expands in a TP air chamber during heating, and this creates positive pressure on liquids located in chambers connected to that chamber. While the TP air chamber and connecting channels are easy to fabricate in a one-level CD manufacturing technique, this approach provides only one way pumping between two chambers, is real-estate hungry and leads to unnecessary heating of liquids in close proximity to the TP chamber. In this paper, we present a novel TP push and pull pumping method which allows for pumping of liquid in any direction between two connected liquid chambers. To ensure that implementation of TP push and pull pumping also addresses the issue of space and heating challenges, a multi-level 3D CD design is developed, and localized forced convection heating, rather than infra-red (IR) is applied. On a multi-level 3D CD, the TP features are placed on a top level separate from the rest of the microfluidic processes that are implemented on a lower separate level. This approach allows for heat shielding of the microfluidic process level, and efficient usage of space on the CD for centrifugal handling of liquids. The use of localized forced convection heating, rather than infra-red (IR) or laser heating in earlier implementations allows not only for TP pumping of liquids while the CD is spinning but also makes heat insulation for TP pumping and other fluidic functions easier. To aid in future implementations of TP push and pull pumping on a multi-level 3D CD, study on CD surface heating is also presented. In this contribution, we also demonstrate an advanced application of pull pumping through the implementation of valve-less switch pumping.

Push pull microfluidics on a multi-level 3D CD

PubMed Central

Thio, Tzer Hwai Gilbert; Ibrahim, Fatimah; Al-Faqheri, Wisam; Moebius, Jacob; Khalid, Noor Sakinah; Soin, Norhayati; Kahar, Maria Kahar Bador Abdul; Madou, Marc

2013-01-01

A technique known as thermo-pneumatic (TP) pumping is used to pump fluids on a microfluidic compact disc (CD) back towards the CD center against the centrifugal force that pushes liquids from the center to the perimeter of the disc. Trapped air expands in a TP air chamber during heating, and this creates positive pressure on liquids located in chambers connected to that chamber. While the TP air chamber and connecting channels are easy to fabricate in a one-level CD manufacturing technique, this approach provides only one way pumping between two chambers, is real-estate hungry and leads to unnecessary heating of liquids in close proximity to the TP chamber. In this paper, we present a novel TP push and pull pumping method which allows for pumping of liquid in any direction between two connected liquid chambers. To ensure that implementation of TP push and pull pumping also addresses the issue of space and heating challenges, a multi-level 3D CD design is developed, and localized forced convection heating, rather than infra-red (IR) is applied. On a multi-level 3D CD, the TP features are placed on a top level separate from the rest of the microfluidic processes that are implemented on a lower separate level. This approach allows for heat shielding of the microfluidic process levels, and efficient usage of space on the CD for centrifugal handling of liquids. The use of localized forced convection heating, rather than infra-red (IR) or laser heating in earlier implementations allows not only for TP pumping of liquids while the CD is spinning but also makes heat insulation for TP pumping and other fluidic functions easier. To aid in future implementations of TP push and pull pumping on a multi-level 3D CD, study on CD surface heating is also presented. In this contribution, we also demonstrate an advanced application of pull pumping through the implementation of valve-less switch pumping. PMID:23774994

Conditions for sustainability of Academic Collaborative Centres for Public Health in the Netherlands: a mixed methods design.

PubMed

Jansen, Maria W J; van Oers, Hans A M; Middelweerd, Mizzi D R; van de Goor, Ien A M; Ruwaard, Dirk

2015-08-21

Contemporary research should increasingly be carried out in the context of application. Nowotny called this new form of knowledge production Mode-2. In line with Mode-2 knowledge production, the Dutch government in 2006 initiated the so-called Academic Collaborative Centres (ACC) for Public Health. The aim of these ACCs is to build a regional, sustainable knowledge-sharing network to deliver socially robust knowledge. The present study aims to highlight the enabling and constraining push and pull factors of these ACCs in order to assess whether the ACCs are able to build and strengthen a sustainable integrated organizational network between public health policy, practice, and research. Our empirical analysis builds on a mixed methods design. Quantitative data was derived from records of a survey sent to all 11 ACCs about personnel investments, number and nature of projects, and earning power. Qualitative data was derived from 21 in-depth interviews with stakeholders involved. The interviews were tape-recorded, transcribed, and manually coded as favourable or unfavourable pull or push factors. The extra funding appeared to be the most enabling push factor. The networks secured external grants for about 150 short- and long-term Mode-2 knowledge production projects in the past years. Enabling pull factors improved, especially the number of policy-driven short-term research projects. Exchange agents were able to constructively deal with the constraining push factors, like university's publication pressure and budget limitations. However, the constraining pull factors like local government's involvement and their low demand for scientific evidence were difficult to overcome. A clear improvement of the organizational networks was noticed whereby the ACC's were pushed rather than pulled. Efforts are needed to increase the demand for scientific and socially robust evidence from policymakers and to resolve the regime differences between the research and policy systems, in order to make the bidirectionality of the links sustainable.

A high-sensitivity push-pull magnetometer

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

Breschi, E.; Grujić, Z. D.; Knowles, P.

2014-01-13

We describe our approach to atomic magnetometry based on the push-pull optical pumping technique. Cesium vapor is pumped and probed by a resonant laser beam whose circular polarization is modulated synchronously with the spin evolution dynamics induced by a static magnetic field. The magnetometer is operated in a phase-locked loop, and it has an intrinsic sensitivity below 20fT/√(Hz), using a room temperature paraffin-coated cell. We use the magnetometer to monitor magnetic field fluctuations with a sensitivity of 300fT/√(Hz)

Branched actin networks push against each other at adherens junctions to maintain cell-cell adhesion.

PubMed

Efimova, Nadia; Svitkina, Tatyana M

2018-05-07

Adherens junctions (AJs) are mechanosensitive cadherin-based intercellular adhesions that interact with the actin cytoskeleton and carry most of the mechanical load at cell-cell junctions. Both Arp2/3 complex-dependent actin polymerization generating pushing force and nonmuscle myosin II (NMII)-dependent contraction producing pulling force are necessary for AJ morphogenesis. Which actin system directly interacts with AJs is unknown. Using platinum replica electron microscopy of endothelial cells, we show that vascular endothelial (VE)-cadherin colocalizes with Arp2/3 complex-positive actin networks at different AJ types and is positioned at the interface between two oppositely oriented branched networks from adjacent cells. In contrast, actin-NMII bundles are located more distally from the VE-cadherin-rich zone. After Arp2/3 complex inhibition, linear AJs split, leaving gaps between cells with detergent-insoluble VE-cadherin transiently associated with the gap edges. After NMII inhibition, VE-cadherin is lost from gap edges. We propose that the actin cytoskeleton at AJs acts as a dynamic push-pull system, wherein pushing forces maintain extracellular VE-cadherin transinteraction and pulling forces stabilize intracellular adhesion complexes. © 2018 Efimova and Svitkina.

Automatic Avoidance Tendencies in Individuals with Contamination-Related Obsessive-Compulsive Symptoms

PubMed Central

Najmi, Sadia; Kuckertz, Jennie M.; Amir, Nader

2010-01-01

We used an Approach-Avoidance Task (AAT) to examine response to threatening stimuli in 20 individuals high in contamination-related obsessive-compulsive symptoms (HCs) and 21 individuals low in contamination-related obsessive-compulsive symptoms (LCs). Participants were instructed to respond to contamination-related and neutral pictures by pulling a joystick towards themselves or by pushing it away from themselves. Moving the joystick changed the size of the image to simulate approaching or distancing oneself from the object. Consistent with our hypothesis, the HC group was significantly slower in pulling contamination-related pictures than in pulling neutral pictures, whereas in the LC group there was no difference between speed of pulling contamination-related pictures and neutral pictures. Contrary to our hypothesis, we did not find support for faster pushing away of contamination-related pictures than neutral pictures by the HC group. Moreover, the degree of avoidance of contamination-related stimuli when pulling – but not when pushing – was significantly correlated with self-reported contamination-related obsessive-compulsive symptoms. These results suggest a biased behavioral response for threatening objects in individuals high in contamination fears only when inhibiting the prepotent response to avoid threatening stimuli and not when performing a practiced avoidance response. Thus, our results validate the use of the AAT as a measure of inhibited and uninhibited automatic avoidance reactions to emotional information in individuals with contamination-related obsessive-compulsive symptoms. PMID:20650448

Treatment of patients with a congenital transversal vaginal septum or a partial aplasia of the vagina. The vaginal pull-through versus the push-through technique.

PubMed

van Bijsterveldt, Chantal; Willemsen, Wim

2009-06-01

The aim of this study is to describe the different modalities of congenital obstructing vaginal malformations and the evaluation of techniques to solve the problem. A retrospective study. The University Hospital Nijmegen, the Netherlands. The medical records of 18 patients with congenital obstructive malformations of the vagina operated on by one gynecologist were retrospectively reviewed. The conditions were classified in three groups: group I with one uterus and vagina and with a transverse vaginal septum, group II with a partial vaginal agenesis and group III with a double genital system and a septum with occlusion of one vagina. Operating technique used, mold treatment after surgery, menstruation outflow, the possibility of having intercourse and the need for additional surgery. 18 patients were evaluated. Of 10 patients in group I, 8 patients were treated with the pull-through technique and 2 patients with the push-through technique. Four of the patients with a pull-through operation did not get mold treatment; of these patients, 3 needed repeat surgery because of the tendency for constriction. Of 4 patients in group II, 1 patient was treated with the pull-through technique and 3 with the push-through technique. The patient with the pull-through technique needed repeat surgery because of constriction. There was no mold treatment after the first procedure. Group III were 4 patients all treated with the pull-through technique. None of them received mold treatment, and none of these patients needed repeat surgery. The push-through method is a good surgical technique for the patients in whom problems of constriction after surgery are expected and for patients with difficulties during surgery. Mold treatment is recommended after surgery in patients with a thick transversal vaginal septum or a partial vaginal aplasia.

The Baltimore Therapeutic Equipment work simulator: biomechanical and physiological norms for three attachments in healthy men.

PubMed

Bhambhani, Y; Esmail, S; Brintnell, S

1994-01-01

The Baltimore Therapeutic Equipment (BTE) work simulator is routinely used by occupational therapists in functional capacity evaluation. Currently, there is a lack of normative data for various attachments on this instrument. The purposes of this study were to (a) establish norms for the biomechanical and physiological responses during three tasks on the BTE work simulator, namely, wheel-turn, push-pull, and overhead-reach; (b) compare these responses during the three tasks, and (c) examine the interrelationships of these responses during the tasks. Twenty healthy men completed five testing sessions: (a) task familiarization on the BTE work simulator to identify the work intensity, which was perceived as hard on the Borg scale; (b) an incremental arm ergometer exercise test to determine their peak oxygen uptake (pVO2) and peak heart rate (pHR); and (c) one of the three tasks on the BTE work simulator for 4 min in each of the next three sessions. Analysis of variance indicated that torque, work, and power during the overhead-reach were significantly higher (p = .000) compared with the wheel-turn and push-pull tasks. However, no significant differences (p > .05) were observed among the tasks for the VO2 and HR, which were approximately 50% and 70% of pVO2 and pHR respectively. Although there was a significant relationship (p < .05) among tasks for the torque, work, and power, the common variance ranged only between 38% and 67%. The relative pVO2 was significantly related to work (p = .028) and power (p = .027) only during the push-pull task but not the wheel-turn and overhead-reach tasks. These results suggest that occupational therapists should include as many tasks as possible when designing functional capacity evaluation test batteries, and that there is no consistent relationship between cardiorespiratory fitness and performance of various tasks on the BTE work simulator.

Analysis of a spaceborne mirror on a main plate with isostatic mounts

NASA Astrophysics Data System (ADS)

Chan, Chia-Yen; Lien, Chun-Chieh; Huang, Po-Hsuan; Chang, Shenq-Tsong; Huang, Ting-Ming

2014-09-01

The paper is aimed at obtaining the deformation results and optical aberration configurations of a spaceborne mirror made of ZERODUR® glass on a main plate with three isostatic mounts for a space Cassegrain telescope. On the rear side of the main plate four screws will be locked to fix the focal plane assembly. The locking modes for the four screws will be simulated as push and pull motions in the Z axis for simplification. The finite element analysis and Zernike polynomial fitting are applied to the whole integrated optomechanical analysis process. Under the analysis, three isostatic mounts are bonded to the neutral plane of the mirror. The deformation results and optical aberration configurations under six types of push and pull motions as well as self-weight loading have been obtained. In addition, the comparison between the results under push and pull motions with 0.01 mm and 0.1 mm displacements in Z axis will be attained.

30 CFR 75.1403-10 - Criteria-Haulage; general.

Code of Federal Regulations, 2013 CFR

2013-07-01

...) Warning lights or reflective signs or tapes should be installed along haulage roads at locations of abrupt... pulled by animals. (b) Cars on main haulage roads should not be pushed, except where necessary to push...

30 CFR 75.1403-10 - Criteria-Haulage; general.

Code of Federal Regulations, 2012 CFR

2012-07-01

...) Warning lights or reflective signs or tapes should be installed along haulage roads at locations of abrupt... pulled by animals. (b) Cars on main haulage roads should not be pushed, except where necessary to push...

30 CFR 75.1403-10 - Criteria-Haulage; general.

Code of Federal Regulations, 2010 CFR

2010-07-01

...) Warning lights or reflective signs or tapes should be installed along haulage roads at locations of abrupt... pulled by animals. (b) Cars on main haulage roads should not be pushed, except where necessary to push...

30 CFR 75.1403-10 - Criteria-Haulage; general.

Code of Federal Regulations, 2011 CFR

2011-07-01

...) Warning lights or reflective signs or tapes should be installed along haulage roads at locations of abrupt... pulled by animals. (b) Cars on main haulage roads should not be pushed, except where necessary to push...

30 CFR 75.1403-10 - Criteria-Haulage; general.

Code of Federal Regulations, 2014 CFR

2014-07-01

...) Warning lights or reflective signs or tapes should be installed along haulage roads at locations of abrupt... pulled by animals. (b) Cars on main haulage roads should not be pushed, except where necessary to push...

Pushing Back against Push-In: ESOL Teacher Resistance and the Complexities of Coteaching

ERIC Educational Resources Information Center

McClure, Greg; Cahnmann-Taylor, Melisa

2010-01-01

As U. S. school districts struggle to address persistent achievement gaps between increasing numbers of English language learners (ELLs) and their native-English-speaking counterparts, many districts are moving away from segregative models like pull-out to implement more collaborative approaches such as coteaching, or push-in. In contrast to…

Physical Limits on the Precision of Mitotic Spindle Positioning by Microtubule Pushing forces: Mechanics of mitotic spindle positioning.

PubMed

Howard, Jonathon; Garzon-Coral, Carlos

2017-11-01

Tissues are shaped and patterned by mechanical and chemical processes. A key mechanical process is the positioning of the mitotic spindle, which determines the size and location of the daughter cells within the tissue. Recent force and position-fluctuation measurements indicate that pushing forces, mediated by the polymerization of astral microtubules against- the cell cortex, maintain the mitotic spindle at the cell center in Caenorhabditis elegans embryos. The magnitude of the centering forces suggests that the physical limit on the accuracy and precision of this centering mechanism is determined by the number of pushing microtubules rather than by thermally driven fluctuations. In cells that divide asymmetrically, anti-centering, pulling forces generated by cortically located dyneins, in conjunction with microtubule depolymerization, oppose the pushing forces to drive spindle displacements away from the center. Thus, a balance of centering pushing forces and anti-centering pulling forces localize the mitotic spindles within dividing C. elegans cells. © 2017 The Authors. BioEssays published by Wiley Periodicals, Inc.

A push-pull system to reduce house entry of malaria mosquitoes

PubMed Central

2014-01-01

Background Mosquitoes are the dominant vectors of pathogens that cause infectious diseases such as malaria, dengue, yellow fever and filariasis. Current vector control strategies often rely on the use of pyrethroids against which mosquitoes are increasingly developing resistance. Here, a push-pull system is presented, that operates by the simultaneous use of repellent and attractive volatile odorants. Method/Results Experiments were carried out in a semi-field set-up: a traditional house which was constructed inside a screenhouse. The release of different repellent compounds, para-menthane-3,8-diol (PMD), catnip oil e.o. and delta-undecalactone, from the four corners of the house resulted in significant reductions of 45% to 81.5% in house entry of host-seeking malaria mosquitoes. The highest reductions in house entry (up to 95.5%), were achieved by simultaneously repelling mosquitoes from the house (push) and removing them from the experimental set-up using attractant-baited traps (pull). Conclusions The outcome of this study suggests that a push-pull system based on attractive and repellent volatiles may successfully be employed to target mosquito vectors of human disease. Reductions in house entry of malaria vectors, of the magnitude that was achieved in these experiments, would likely affect malaria transmission. The repellents used are non-toxic and can be used safely in a human environment. Delta-undecalactone is a novel repellent that showed higher effectiveness than the established repellent PMD. These results encourage further development of the system for practical implementation in the field. PMID:24674451

Predicting the denitrification capacity of sandy aquifers from in situ measurements using push-pull 15N tracer tests

NASA Astrophysics Data System (ADS)

Eschenbach, W.; Well, R.; Walther, W.

2014-12-01

Knowledge about the spatial variability of in situ denitrification rates (Dr(in situ)) and their relation to the denitrification capacity in nitrate-contaminated aquifers is crucial to predict the development of groundwater quality. Therefore, 28 push-pull 15N tracer tests for the measurement of in situ denitrification rates were conducted in two sandy Pleistocene aquifers in Northern Germany. The 15N analysis of denitrification derived 15N labelled N2 and N2O dissolved in water samples collected during the push-pull 15N tracer tests was performed by isotope ratio mass spectrometry (IRMS) in the lab and additionally for some tracer tests online in the field with a quadrupole membrane inlet mass spectrometer (MIMS), in order to test the feasibility of on-site real-time 15N analysis. Aquifer material from the same locations and depths as the push-pull injection points was incubated and the initial and cumulative denitrification after one year of incubation (Dcum(365)) as well as the stock of reduced compounds (SRC) was compared with in situ measurements of denitrification. This was done to derive transfer functions suitable to predict Dcum(365) and SRC from Dr(in situ). Dr(in situ) ranged from 0 to 51.5 μg N kg-1 d-1. Denitrification rates derived from on-site isotope analysis using membrane-inlet mass spectrometry satisfactorily coincided with laboratory analysis by conventional isotope ratio mass spectrometry, thus proving the feasibility of in situ analysis. Dr(in situ) was significantly higher in the sulphidic zone of both aquifers compared to the zone of non-sulphidic aquifer material. Overall, regressions between the Dcum(365) and SRC of the tested aquifer material with Dr(in situ) exhibited only a modest linear correlation for the full data set. But the predictability of Dcum(365) and SRC from Dr(in situ) data clearly increased for aquifer samples from the zone of NO3--bearing groundwater. In the NO3--free aquifer zone a lag phase of denitrification after NO3- injections was observed, which confounded the relationship between reactive compounds and in situ denitrification activity. This finding was attributed to adaptation processes in the microbial community after NO3- injections. Exemplarily, it was demonstrated that the microbial community in the NO3--free zone close below the NO3--bearing zone can be adapted to denitrification by amending wells with NO3--injections for an extended period. In situ denitrification rates were 30 to 65% higher after pre-conditioning with NO3-. Results from this study suggest that such pre-conditioning is crucial for the measurement of Dr(in situ) in deeper aquifer material from the NO3--free groundwater zone and thus for the prediction of Dcum(365) and SRC from Dr(in situ).

Predicting the denitrification capacity of sandy aquifers from in situ measurements using push-pull 15N tracer tests

NASA Astrophysics Data System (ADS)

Eschenbach, W.; Well, R.; Walther, W.

2015-04-01

Knowledge about the spatial variability of in situ denitrification rates (Dr(in situ)) and their relation to the denitrification capacity in nitrate-contaminated aquifers is crucial to predict the development of groundwater quality. Therefore, 28 push-pull 15N tracer tests for the measurement of in situ denitrification rates were conducted in two sandy Pleistocene aquifers in northern Germany. The 15N analysis of denitrification-derived 15N-labelled N2 and N2O dissolved in water samples collected during the push-pull 15N tracer tests was performed using isotope ratio mass spectrometry (IRMS) in the lab and additionally for some tracer tests online in the field with a quadrupole membrane inlet mass spectrometer (MIMS) in order to test the feasibility of on-site real-time 15N analysis. Aquifer material from the same locations and depths as the push-pull injection points was incubated, and the initial and cumulative denitrification after 1 year of incubation (Dcum(365)) as well as the stock of reduced compounds (SRC) was compared with in situ measurements of denitrification. This was done to derive transfer functions suitable to predict Dcum(365) and SRC from Dr(in situ). Dr(in situ) ranged from 0 to 51.5 μg N kg-1 d-1. Denitrification rates derived from on-site isotope analysis using MIMS satisfactorily coincided with laboratory analysis by conventional IRMS, thus proving the feasibility of in situ analysis. Dr(in situ) was significantly higher in the sulfidic zone of both aquifers compared to the zone of non-sulfidic aquifer material. Overall, regressions between the Dcum(365) and SRC of the tested aquifer material with Dr(in situ) exhibited only a modest linear correlation for the full data set. However, the predictability of Dcum(365) and SRC from Dr(in situ) data clearly increased for aquifer samples from the zone of NO3--bearing groundwater. In the NO3--free aquifer zone, a lag phase of denitrification after NO3- injections was observed, which confounded the relationship between reactive compounds and in situ denitrification activity. This finding was attributed to adaptation processes in the microbial community after NO3- injections. It was also demonstrated that the microbial community in the NO3--free zone just below the NO3--bearing zone can be adapted to denitrification by NO3- injections into wells for an extended period. In situ denitrification rates were 30 to 65 times higher after pre-conditioning with NO3-. Results from this study suggest that such pre-conditioning is crucial for the measurement of Dr(in situ) in deeper aquifer material from the NO3--free groundwater zone and thus for the prediction of Dcum(365) and SRC from Dr(in situ).

Intraoperative Physical Examination for Diagnosis of Interosseous Ligament Rupture-Cadaveric Study.

PubMed

Kachooei, Amir Reza; Rivlin, Michael; Wu, Fei; Faghfouri, Aram; Eberlin, Kyle R; Ring, David

2015-09-01

To study the intraobserver and interobserver reliability of the diagnosis of interosseous ligament (IOL) rupture in a cadaver model. On 12 fresh frozen cadavers, radial heads were cut using an identical incision and osteotomy. After randomization, the soft tissues of the limbs were divided into 4 groups: both IOL and triangular fibrocartilage (TFCC) intact; IOL disruption but TFCC intact; both IOL and TFCC divided; and IOL intact but TFCC divided. All incisions had identical suturing. After standard instruction and demonstration of radius pull-push and radius lateral pull tests, 10 physician evaluators with different levels of experience examined the cadaver limbs in a standardized way (elbow at 90° with the forearm held in both supination and pronation) and were asked to classify them into one of the 4 groups. Next, the same examiners were asked to re-examine the limbs after randomly changing the order of examination. The interobserver reliability of agreement for the diagnosis of IOL injury (groups 2 and 3) was fair in both rounds of examination and the intraobserver reliability was moderate. The intra- and interobserver reliabilities of agreement for the 4 groups of injuries among the examiners were fair in both rounds of examination. The sensitivity, specificity, accuracy, positive, and negative predictive values were all around 70%. The likelihood of a positive test corresponding with the presence of IOL rupture (positive likelihood ratio) was 2.2. The likelihood of a negative test correctly diagnosing an intact IOL was 0.40. In cadavers, intraoperative tests had fair reliability and 70% accuracy for the diagnosis of IOL rupture using the push-pull and lateral pull maneuvers. The level of experience did not have any effect on the correct diagnosis of intact versus disrupted IOL. Although not common, some failure of surgeries for traumatic elbow fracture-dislocations is because of failure in timely diagnosis of IOL disruption. Copyright © 2015 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

Intrapartum translabial ultrasound with pushing used to predict the difficulty in vacuum-assisted delivery of fetuses in non-occiput posterior position.

PubMed

Antonio Sainz, José; Borrero, Carlota; Aquise, Adriana; García-Mejido, José Antonio; Gutierrez, Laura; Fernández-Palacín, Ana

2016-10-01

Our aim is to evaluate the capacity of intrapartum translabial ultrasound (ITU) with pushing in the prediction of difficulty of fetal extraction in vacuum assisted deliveries. Prospective, observational study performed (2/2015-8/2015) on 75 nulliparous women, ≥37 weeks with singleton pregnancies at full dilatation who had ITU-with-pushing performed, previous to vacuum-placement for fetal extraction. Working on the translabial sagittal-plane, we assessed: Angle-Progression (AoP), Progression-Distance (PD) and Head-Direction (HD); in the axial plane we evaluated: Midline-Angle (MLA) and Head-Perineum-Distance (HPD). Vacuum extractions were classified as easy-difficulty (ED) (≤3 vacuum-pulls), difficult-unsuccessful (DD) (>3 vacuum-pulls). We did not assess occipito-posterior-presentations. Seventy nulliparous were studied (44-ED,26-DD). We observed no differences in obstetric, neonatal or intrapartum characteristics between the two study groups, with the following exceptions: newborn weight (3272 ± 438 g versus 3540 ± 372 g; p = 0.011) and number of vacuum-pulls (1.4-ED-vs-4.4-DD; p < 0.0005). AoP-pushing was 143.9° ± 14.6° in ED and 115.1°± 12.9° in DD (p < 0.0005); Head-Up was 79.5% versus 38.4% (p < 0.0005); PD-Pushing was 42.7 ± 11.3 mm versus 30.4 ± 9.8 mm (p < 0.0005); MLA-Pushing was 27.6°± 26.6° versus 57.5°±26.5°(p=0.025); HPD-Pushing was 40.8 ± 10.0 mm versus 47.4 ± 10.9 mm (p = 0.039). We identified that the presence of an AoP-Pushing > 128° predicts an Easy-Vacuum-Delivery (≤3 Vacuum-Pulls) in  >85% of cases (Sen 80%-FPR 9.3%).

Push-Pull Tests for Evaluating the Aerobic Cometabolism of Chlorinated Aliphatic Hydrocarbons

DTIC Science & Technology

2006-09-01

Z39-18 i COST & PERFORMANCE REPORT ESTCP Project: ER-9921 TABLE OF CONTENTS Page 1.0 EXECUTIVE SUMMARY...31 iv ACRONYMS AND ABBREVIATIONS ACFEE Air Force Center for Environmental Excellence Br bromine BTEX benzene...ESTCP Environmental Security Technology Certification Program FID flame ionization detector GC gas chromatography HP Hewlett-Packard IC

Push-Pull Tests for Evaluating the Aerobic Cometabolism of Chlorinated Aliphatic Hydrocarbons: Cost & Performance Report

DTIC Science & Technology

2006-09-01

Std Z39-18 i COST & PERFORMANCE REPORT ESTCP Project: ER-9921 TABLE OF CONTENTS Page 1.0 EXECUTIVE SUMMARY...31 iv ACRONYMS AND ABBREVIATIONS ACFEE Air Force Center for Environmental Excellence Br bromine BTEX...Agency ESTCP Environmental Security Technology Certification Program FID flame ionization detector GC gas chromatography HP Hewlett-Packard

Material test machine for tension-compression tests at high temperature

DOEpatents

Cioletti, Olisse C.

1988-01-01

Apparatus providing a device for testing the properties of material specimens at high temperatures and pressures in controlled water chemistries includes, inter alia, an autoclave housing the specimen which is being tested. The specimen is connected to a pull rod which couples out of the autoclave to an external assembly which includes one or more transducers, a force balance chamber and a piston type actuator. The pull rod feeds through the force balance chamber and is compensated thereby for the pressure conditions existing within the autoclave and tending to eject the pull rod therefrom. The upper end of the push rod is connected to the actuator through elements containing a transducer comprising a linear variable differential transformer (LVDT). The housing and coil assembly of the LVDT is coupled to a tube which runs through a central bore of the pull rod into the autoclave where it is connected to one side of the specimen. The movable core of the LVDT is coupled to a stem which runs through the tube where it is then connected to the other side of the specimen through a coupling member. A transducer in the form of a load cell including one or more strain gages is located on a necked-down portion of the upper part of the pull rod intermediate the LVDT and force balance chamber.

[Research progresses on ergonomics assessment and measurement methods for push-pull behavior].

PubMed

Zhao, Yan; Li, Dongxu; Guo, Shengpeng

2011-10-01

Pushing and pulling (P&P) is a common operating mode of operator's physical works, and plays an important role in evaluation of human behavior health and operation performance. At present, there are many research methods of P&P, and this article is a state-of-art review of the classification of P&P research methods, the various impact factors in P&P program, technical details of internal/external P&P force measurement and evaluation, the limitation of current research methods and the future developments in the ergonomics field.

Push-pull with recovery stage high-voltage DC converter for PV solar generator

NASA Astrophysics Data System (ADS)

Nguyen, The Vinh; Aillerie, Michel; Petit, Pierre; Pham, Hong Thang; Vo, Thành Vinh

2017-02-01

A lot of systems are basically developed on DC-DC or DC-AC converters including electronic switches such as MOS or bipolar transistors. The limits of efficiency are quickly reached when high output voltages and high input currents are needed. This work presents a new high-efficiency-high-step-up based on push-pull DC-DC converter integrating recovery stages dedicated to smart HVDC distributed architecture in PV solar energy production systems. Appropriate duty cycle ratio assumes that the recovery stage work with parallel charge and discharge to achieve high step-up voltage gain. Besides, the voltage stress on the main switch is reduced with a passive clamp circuit and thus, low on-state resistance Rdson of the main switch can be adopted to reduce conduction losses. Thus, the efficiency of a basic DC-HVDC converter dedicated to renewable energy production can be further improved with such topology. A prototype converter is developed, and experimentally tested for validation.

Grip Force and 3D Push-Pull Force Estimation Based on sEMG and GRNN

PubMed Central

Wu, Changcheng; Zeng, Hong; Song, Aiguo; Xu, Baoguo

2017-01-01

The estimation of the grip force and the 3D push-pull force (push and pull force in the three dimension space) from the electromyogram (EMG) signal is of great importance in the dexterous control of the EMG prosthetic hand. In this paper, an action force estimation method which is based on the eight channels of the surface EMG (sEMG) and the Generalized Regression Neural Network (GRNN) is proposed to meet the requirements of the force control of the intelligent EMG prosthetic hand. Firstly, the experimental platform, the acquisition of the sEMG, the feature extraction of the sEMG and the construction of GRNN are described. Then, the multi-channels of the sEMG when the hand is moving are captured by the EMG sensors attached on eight different positions of the arm skin surface. Meanwhile, a grip force sensor and a three dimension force sensor are adopted to measure the output force of the human's hand. The characteristic matrix of the sEMG and the force signals are used to construct the GRNN. The mean absolute value and the root mean square of the estimation errors, the correlation coefficients between the actual force and the estimated force are employed to assess the accuracy of the estimation. Analysis of variance (ANOVA) is also employed to test the difference of the force estimation. The experiments are implemented to verify the effectiveness of the proposed estimation method and the results show that the output force of the human's hand can be correctly estimated by using sEMG and GRNN method. PMID:28713231

Grip Force and 3D Push-Pull Force Estimation Based on sEMG and GRNN.

PubMed

Wu, Changcheng; Zeng, Hong; Song, Aiguo; Xu, Baoguo

2017-01-01

The estimation of the grip force and the 3D push-pull force (push and pull force in the three dimension space) from the electromyogram (EMG) signal is of great importance in the dexterous control of the EMG prosthetic hand. In this paper, an action force estimation method which is based on the eight channels of the surface EMG (sEMG) and the Generalized Regression Neural Network (GRNN) is proposed to meet the requirements of the force control of the intelligent EMG prosthetic hand. Firstly, the experimental platform, the acquisition of the sEMG, the feature extraction of the sEMG and the construction of GRNN are described. Then, the multi-channels of the sEMG when the hand is moving are captured by the EMG sensors attached on eight different positions of the arm skin surface. Meanwhile, a grip force sensor and a three dimension force sensor are adopted to measure the output force of the human's hand. The characteristic matrix of the sEMG and the force signals are used to construct the GRNN. The mean absolute value and the root mean square of the estimation errors, the correlation coefficients between the actual force and the estimated force are employed to assess the accuracy of the estimation. Analysis of variance (ANOVA) is also employed to test the difference of the force estimation. The experiments are implemented to verify the effectiveness of the proposed estimation method and the results show that the output force of the human's hand can be correctly estimated by using sEMG and GRNN method.

Optimal Halbach Permanent Magnet Designs for Maximally Pulling and Pushing Nanoparticles

PubMed Central

Sarwar, A.; Nemirovski, A.; Shapiro, B.

2011-01-01

Optimization methods are presented to design Halbach arrays to maximize the forces applied on magnetic nanoparticles at deep tissue locations. In magnetic drug targeting, where magnets are used to focus therapeutic nanoparticles to disease locations, the sharp fall off of magnetic fields and forces with distances from magnets has limited the depth of targeting. Creating stronger forces at depth by optimally designed Halbach arrays would allow treatment of a wider class of patients, e.g. patients with deeper tumors. The presented optimization methods are based on semi-definite quadratic programming, yield provably globally optimal Halbach designs in 2 and 3-dimensions, for maximal pull or push magnetic forces (stronger pull forces can collect nano-particles against blood forces in deeper vessels; push forces can be used to inject particles into precise locations, e.g. into the inner ear). These Halbach designs, here tested in simulations of Maxwell’s equations, significantly outperform benchmark magnets of the same size and strength. For example, a 3-dimensional 36 element 2000 cm3 volume optimal Halbach design yields a ×5 greater force at a 10 cm depth compared to a uniformly magnetized magnet of the same size and strength. The designed arrays should be feasible to construct, as they have a similar strength (≤ 1 Tesla), size (≤ 2000 cm3), and number of elements (≤ 36) as previously demonstrated arrays, and retain good performance for reasonable manufacturing errors (element magnetization direction errors ≤ 5°), thus yielding practical designs to improve magnetic drug targeting treatment depths. PMID:23335834

Optimal Halbach Permanent Magnet Designs for Maximally Pulling and Pushing Nanoparticles.

PubMed

Sarwar, A; Nemirovski, A; Shapiro, B

2012-03-01

Optimization methods are presented to design Halbach arrays to maximize the forces applied on magnetic nanoparticles at deep tissue locations. In magnetic drug targeting, where magnets are used to focus therapeutic nanoparticles to disease locations, the sharp fall off of magnetic fields and forces with distances from magnets has limited the depth of targeting. Creating stronger forces at depth by optimally designed Halbach arrays would allow treatment of a wider class of patients, e.g. patients with deeper tumors. The presented optimization methods are based on semi-definite quadratic programming, yield provably globally optimal Halbach designs in 2 and 3-dimensions, for maximal pull or push magnetic forces (stronger pull forces can collect nano-particles against blood forces in deeper vessels; push forces can be used to inject particles into precise locations, e.g. into the inner ear). These Halbach designs, here tested in simulations of Maxwell's equations, significantly outperform benchmark magnets of the same size and strength. For example, a 3-dimensional 36 element 2000 cm(3) volume optimal Halbach design yields a ×5 greater force at a 10 cm depth compared to a uniformly magnetized magnet of the same size and strength. The designed arrays should be feasible to construct, as they have a similar strength (≤ 1 Tesla), size (≤ 2000 cm(3)), and number of elements (≤ 36) as previously demonstrated arrays, and retain good performance for reasonable manufacturing errors (element magnetization direction errors ≤ 5°), thus yielding practical designs to improve magnetic drug targeting treatment depths.

Evaluation of a peridomestic mosquito trap for integration into an Aedes aegypti (Diptera: Culicidae) push-pull control strategy.

PubMed

Salazar, Ferdinand V; Achee, Nicole L; Grieco, John P; Prabaripai, Atchariya; Eisen, Lars; Shah, Pankhil; Chareonviriyaphap, Theeraphap

2012-06-01

We determined the feasibility of using the BG-Sentinel™ mosquito trap (BGS) as the pull component in a push-pull strategy to reduce indoor biting by Aedes aegypti. This included evaluating varying numbers of traps (1-4) and mosquito release numbers (10, 25, 50, 100, 150, 200, and 250) on recapture rates under screen house conditions. Based on these variations in trap and mosquito numbers, release intervals were rotated through a completely randomized design with environmental factors (temperature, relative humidity, and light intensity) and monitored throughout each experiment. Data from four sampling time points (05:30, 09:30, 13:30, and 17:30) indicate a recapture range among treatments of 66-98%. Furthermore, 2-3 traps were as effective in recapturing mosquitoes as 4 traps for all mosquito release numbers. Time trends indicate Day 1 (the day the mosquitoes were released) as the "impact period" for recapture with peak numbers of marked mosquitoes collected at 09:30 or 4 h post-release. Information from this study will be used to guide the configuration of the BGS trap component of a push-pull vector control strategy currently in the proof-of-concept stage of development in Thailand and Peru. © 2012 The Society for Vector Ecology.

Ultrafine particle air pollution inside diesel-propelled passenger trains.

PubMed

Abramesko, Victoria; Tartakovsky, Leonid

2017-07-01

Locomotives with diesel engines are used worldwide and are an important source of air pollution. Pollutant emissions by locomotive engines affect the air quality inside passenger trains. This study is aimed at investigating ultrafine particle (UFP) air pollution inside passenger trains and providing a basis for assessing passenger exposure to this pollutant. The concentrations of UFPs inside the carriages of push-pull trains are dramatically higher when the train operates in pull mode. This clearly shows that locomotive engine emissions are a dominant factor in train passengers' exposure to UFPs. The highest levels of UFP air pollution are observed inside the carriages of pull trains close to the locomotive. In push mode, the UFP number concentrations were lower by factors of 2.6-43 (depending on the carriage type) compared to pull mode. The UFP concentrations are substantially lower in diesel multiple-unit trains than in trains operating in pull mode. A significant influence of the train movement regime on the UFP NC inside a carriage is observed. Copyright © 2017 Elsevier Ltd. All rights reserved.

UPPER BODY PUSH AND PULL STRENGTH RATIO IN RECREATIONALLY ACTIVE ADULTS

PubMed Central

Hanney, William J.; Pabian, Patrick; Kolber, Morey J.

2013-01-01

Introduction: Agonist to antagonist strength data is commonly analyzed due to its association with injury and performance. The purpose of this study was to examine the agonist to antagonist ratio of upper body strength using two simple field tests (timed push up/timed modified pull up) in recreationally active adults and to establish the basis for reference standards. Methods: One hundred eighty (180) healthy recreationally active adults (111 females and 69 males, aged 18‐45 years) performed two tests of upper body strength in random order: 1. Push‐ups completed during 3 sets of 15 seconds with a 45 second rest period between each set and 2. Modified pull‐ups completed during 3 sets of 15 seconds with a 45 second rest period between each set. Results: The push‐up to modified pull‐up ratio for the males was 1.57:1, whereas females demonstrated a ratio of 2.72:1. The results suggest that for our group of healthy recreationally active subjects, the upper body “pushing” musculature is approximately 1.5–2.7 times stronger than the musculature involved for pulling. Conclusions: In this study, these recreationally active adults displayed greater strength during the timed push‐ups than the modified pull‐ups. The relationship of these imbalances to one's performance and or injury risk requires further investigation. The reference values, however, may serve the basis for future comparison and prospective investigations. The field tests in this study can be easily implemented by clinicians and an agonist/antagonist ratio can be determined and compared to our findings. Level of Evidence: 2b PMID:23593552

Fluctuations uncover a distinct class of traveling waves

PubMed Central

Korolev, Kirill S.

2018-01-01

Epidemics, flame propagation, and cardiac rhythms are classic examples of reaction–diffusion waves that describe a switch from one alternative state to another. Only two types of waves are known: pulled, driven by the leading edge, and pushed, driven by the bulk of the wave. Here, we report a distinct class of semipushed waves for which both the bulk and the leading edge contribute to the dynamics. These hybrid waves have the kinetics of pushed waves, but exhibit giant fluctuations similar to pulled waves. The transitions between pulled, semipushed, and fully pushed waves occur at universal ratios of the wave velocity to the Fisher velocity. We derive these results in the context of a species invading a new habitat by examining front diffusion, rate of diversity loss, and fluctuation-induced corrections to the expansion velocity. All three quantities decrease as a power law of the population density with the same exponent. We analytically calculate this exponent, taking into account the fluctuations in the shape of the wave front. For fully pushed waves, the exponent is −1, consistent with the central limit theorem. In semipushed waves, however, the fluctuations average out much more slowly, and the exponent approaches 0 toward the transition to pulled waves. As a result, a rapid loss of genetic diversity and large fluctuations in the position of the front occur, even for populations with cooperative growth and other forms of an Allee effect. The evolutionary outcome of spatial spreading in such populations could therefore be less predictable than previously thought. PMID:29610340

Fluctuations uncover a distinct class of traveling waves.

PubMed

Birzu, Gabriel; Hallatschek, Oskar; Korolev, Kirill S

2018-04-17

Epidemics, flame propagation, and cardiac rhythms are classic examples of reaction-diffusion waves that describe a switch from one alternative state to another. Only two types of waves are known: pulled, driven by the leading edge, and pushed, driven by the bulk of the wave. Here, we report a distinct class of semipushed waves for which both the bulk and the leading edge contribute to the dynamics. These hybrid waves have the kinetics of pushed waves, but exhibit giant fluctuations similar to pulled waves. The transitions between pulled, semipushed, and fully pushed waves occur at universal ratios of the wave velocity to the Fisher velocity. We derive these results in the context of a species invading a new habitat by examining front diffusion, rate of diversity loss, and fluctuation-induced corrections to the expansion velocity. All three quantities decrease as a power law of the population density with the same exponent. We analytically calculate this exponent, taking into account the fluctuations in the shape of the wave front. For fully pushed waves, the exponent is -1, consistent with the central limit theorem. In semipushed waves, however, the fluctuations average out much more slowly, and the exponent approaches 0 toward the transition to pulled waves. As a result, a rapid loss of genetic diversity and large fluctuations in the position of the front occur, even for populations with cooperative growth and other forms of an Allee effect. The evolutionary outcome of spatial spreading in such populations could therefore be less predictable than previously thought. Copyright © 2018 the Author(s). Published by PNAS.

Novel push-pull fluorescent dyes - 7-(diethylamino)furo- and thieno[3,2-c]coumarins derivatives: structure, electronic spectra and TD-DFT study

NASA Astrophysics Data System (ADS)

Akchurin, Igor O.; Yakhutina, Anna I.; Bochkov, Andrei Y.; Solovjova, Natalya P.; Medvedev, Michael G.; Traven, Valerii F.

2018-05-01

Novel push-pull fluorescent dyes - 7-(diethylamino)furo- and 7-(diethylamino)thieno[3,2-c]coumarins derivatives have been synthesized using formyl derivatives of furo- and thieno[3,2-c]coumarins as starting materials. Electron absorption and fluorescent spectra of the dyes have been recorded in different solvents. Structure and solvent effects on the dyes spectral characteristics were analyzed. The fusion of five-membered heterocycle to coumarin provides a definite increase of Stokes shifts in all solvents and results in higher quantum yields of fluorescence. The absorption and emission bands of thieno[3,2-c] coumarin derivatives are definitely shifted to the red region (3-30 nm) compared to similar derivatives of furo[3,2-c]coumarin. TD-DFT calculations of some of the studied compounds have shown that hybrid DFT functionals and adequate representation of molecular environment are essential for obtaining accurate UV-Vis absorption spectra for the dyes with extended π-system. The longest-wave electron transitions in the studied compounds were computationally shown to be of push-pull nature.

Transformation from a Single Antenna to a Series Array Using Push/Pull Origami

PubMed Central

Shah, Syed Imran Hussain

2017-01-01

We propose a push/pull origami antenna, transformable between a single antenna element and a three-element array. In limited space, the proposed origami antenna can work as a single antenna. When the space is not limited and a higher gain is required, the proposed origami antenna can be transformed to a series antenna array by pulling the frame. In order to push the antenna array back to a single antenna, the frame for each antenna element size must be different. The frame and supporting dielectric materials are built using a three-dimensional (3D) printer. The conductive patterns are inkjet-printed on paper. Thus, the proposed origami antenna is built using hybrid printing technology. The 10-dB impedance bandwidth is 2.5–2.65 GHz and 2.48–2.62 GHz for the single-antenna and array mode, respectively, and the peak gains in the single-antenna and array mode are 5.8 dBi and 7.6 dBi, respectively. The proposed antenna can be used for wireless remote-sensing applications. PMID:28846603

Transformation from a Single Antenna to a Series Array Using Push/Pull Origami.

PubMed

Shah, Syed Imran Hussain; Lim, Sungjoon

2017-08-26

We propose a push/pull origami antenna, transformable between a single antenna element and a three-element array. In limited space, the proposed origami antenna can work as a single antenna. When the space is not limited and a higher gain is required, the proposed origami antenna can be transformed to a series antenna array by pulling the frame. In order to push the antenna array back to a single antenna, the frame for each antenna element size must be different. The frame and supporting dielectric materials are built using a three-dimensional (3D) printer. The conductive patterns are inkjet-printed on paper. Thus, the proposed origami antenna is built using hybrid printing technology. The 10-dB impedance bandwidth is 2.5-2.65 GHz and 2.48-2.62 GHz for the single-antenna and array mode, respectively, and the peak gains in the single-antenna and array mode are 5.8 dBi and 7.6 dBi, respectively. The proposed antenna can be used for wireless remote-sensing applications.

Information Foraging in Nuclear Power Plant Control Rooms

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

R.L. Boring

2011-09-01

nformation foraging theory articulates the role of the human as an 'informavore' that seeks information and follows optimal foraging strategies (i.e., the 'information scent') to find meaningful information. This paper briefly reviews the findings from information foraging theory outside the nuclear domain and then discusses the types of information foraging strategies operators employ for normal and off-normal operations in the control room. For example, operators may employ a predatory 'wolf' strategy of hunting for information in the face of a plant upset. However, during routine operations, the operators may employ a trapping 'spider' strategy of waiting for relevant indicators tomore » appear. This delineation corresponds to information pull and push strategies, respectively. No studies have been conducted to determine explicitly the characteristics of a control room interface that is optimized for both push and pull information foraging strategies, nor has there been empirical work to validate operator performance when transitioning between push and pull strategies. This paper explores examples of control room operators as wolves vs. spiders and con- cludes by proposing a set of research questions to investigate information foraging in control room settings.« less

Enhanced isoprene biosynthesis in Saccharomyces cerevisiae by engineering of the native acetyl-CoA and mevalonic acid pathways with a push-pull-restrain strategy.

PubMed

Lv, Xiaomei; Xie, Wenping; Lu, Wenqiang; Guo, Fei; Gu, Jiali; Yu, Hongwei; Ye, Lidan

2014-09-30

To explore the capacity of isoprene production in Saccharomyces cerevisiae, a rational push-pull-restrain strategy was proposed to engineer the mevalonic acid (MVA) and acetyl-CoA pathways. The strategy can be decomposed into the up-regulation of precursor supply in the acetyl-CoA module and the MVA pathway (push-strategy), increase of the isoprene branch flux (pull-strategy), and down-regulation of the competing pathway (restrain-strategy). Furthermore, to reduce the production cost arising from galactose addition and meanwhile maintain the high expression of Gal promoters, the galactose regulatory network was modulated by Gal80p deletion. Finally, the engineered strain YXM10-ispS-ispS could accumulate up to 37 mg/L isoprene (about 782-fold increase compared to the parental strain) under aerobic conditions with glycerol-sucrose as carbon source. In this way, a new potential platform for isoprene production was established via metabolic engineering of the yeast native pathways. Copyright © 2014 Elsevier B.V. All rights reserved.

Strength Testing in the Air Force: Current Processes and Suggestions for Improvements

DTIC Science & Technology

2014-01-01

Electrical Power Production 4Y0X1 Dental Assistant 3E1X1 Heating, Ventilation, AC, & Refrigeration 4Y0X2 Dental Laboratory 3E2X1 Pavements and...MAFS AFE SF AFU-AS EOD Push 29 -- 22 -- 113 72 111 62 Pull 22 -- 21 -- -- -- 82 -- Cary 19 57 20 -- 188 120 77 -- Hold -- -- -- -- -- -- 64

Ventilation planning at Energy West's Deer Creek mine

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

Tonc, L.; Prosser, B.; Gamble, G.

2009-08-15

In 2004 ventilation planning was initiated to exploit a remote area of Deer Creek mine's reserve (near Huntington, Utah), the Mill Fork Area, located under a mountain. A push-pull ventilation system was selected. This article details the design process of the ventilation system upgrade, the procurement process for the new fans, and the new fan startup testing. 5 figs., 1 photo.

On optimal control problem for conservation law modelling one class of highly re-entrant production systems

NASA Astrophysics Data System (ADS)

D'Apice, Ciro; Kogut, Peter I.

2017-07-01

We discuss the optimal control problem stated as the minimization in the L2-sense of the mismatch between the actual out-flux and a demand forecast for a hyperbolic conservation law that models a highly re-entrant production system. The output of the factory is described as a function of the work in progress and the position of the so-called push-pull point (PPP) where we separate the beginning of the factory employing a push policy from the end of the factory, which uses a pull policy.

Commercial Scholarship: Spinning Physics Research into a Business Enterprise

NASA Astrophysics Data System (ADS)

Butler, Orville

2013-03-01

The American Institute of Physics' Center for History of Physics has conducted a three year NSF funded study of physicist entrepreneurs during which we interviewed 140 physicists who have founded ninety-one startups. Forty of those companies have spun research out of twenty-some universities. Startups spun out of university research tend to be technology push companies, creating new potentially disruptive technologies for which markets do not yet clearly exist, in contrast to market pull companies founded to address innovations responding to market demands. This paper addresses the unique issues found in university spinout companies and their responses to them. While technology push companies are generally considered to be higher risk compared to market pull companies, the university spinouts in our study had a higher rate of both SBIR and venture capital funding than did the market pull companies in our study.

Upper and lower limb functionality: are these compromised in obese children?

PubMed

Riddiford-Harland, Diane L; Steele, Julie R; Baur, Louise A

2006-01-01

The aim of this study was to investigate the effects of obesity on upper and lower limb functional strength and power in children, and to determine whether the ability to perform the daily activity of rising from a chair was compromised in obese children. It was hypothesised that obese children would display less upper and lower limb functionality compared to their non-obese counterparts. Upper and lower limb strength and power of 43 obese children (aged 8.4 +/- 0.5 y, BMI 24.1 +/- 2.3 kg/m(-2)) and 43 non-obese controls (aged 8.4 +/- 0.5 y, BMI 16.9 +/- 0.4 kg/m(-2)) were assessed using age-appropriate field-based tests: arm push/pull ability; basketball throw; vertical jump (VJ), and standing long jump (SLJ) performance. Functional lower limb strength was assessed for 13 obese and 13 non-obese children by quantifying their chair rising ability. Although obese children displayed significantly greater upper limb push (9.3 +/- 2.3 kg) and pull strength (9.6 +/- 3.0 kg) than their non-obese peers (push: 8.8 +/- 2.2 kg; pull: 8.8 +/- 2.3 kg; p < or = 0.05), their VJ (22.1 +/- 4.3 cm) and SLJ (94.6 +/- 12.8 cm) performance was significantly impaired relative to the non-obese children (VJ: 24.7 +/- 4.0 cm; SLJ: 101.7 +/- 14.0 cm; p < or = 0.05). Obese children spent significantly more time during all transfer phases of the chair rising task, compared to the non-obese children. Lower limb functionality in young obese children is impeded when they move their greater body mass against gravity.

Explicit and implicit approach vs. avoidance tendencies towards high vs. low calorie food cues in patients with anorexia nervosa and healthy controls.

PubMed

Paslakis, Georgios; Kühn, Simone; Schaubschläger, Anke; Schieber, Katharina; Röder, Kathrin; Rauh, Elisabeth; Erim, Yesim

2016-12-01

Patients with anorexia nervosa (AN) have a strong ability to limit food intake. Thus, dysfunctional approach vs. avoidance behaviors towards food are evident in AN. We applied an approach-avoidance task (AAT), in which n = 41 AN patients and n = 42 controls either approached ("pull") or avoided ("push") high (HC) vs. low calorie (LC) food pictures based solely on the presented picture format (landscape vs. portrait). We tested the hypothesis that -in opposition to controls displaying an approach bias towards HC food cues- AN patients would show an avoidance bias (measured as different response times) towards HC food. Explicit ratings of food cues were also performed. We found a significant interaction "group" x "direction" (p = 0.03). rm-ANOVAs performed for each of the two groups separately showed a main effect for "direction" of motion in controls (p = 0.02), but not in AN patients (p = 0.40). The two groups did not differ in their reaction times (RTs) with regard to "push" (p = 0.27). However, RTs with regard to "pull" were significantly different between the groups (p = 0.04). Controls show a clear approach bias, expressed by significantly faster RTs for "pull" compared to "push", independent of "calorie" content of the food stimuli. This approach bias is absent in the group of AN patients. This is indicative of a global loss of incentive value of food in AN. Implicit trainings as add-on to psychotherapy in AN patients are asked for. Copyright © 2016 Elsevier Ltd. All rights reserved.

Sapphire reinforced alumina matrix composites

NASA Technical Reports Server (NTRS)

Jaskowiak, Martha H.; Setlock, John A.

1994-01-01

Unidirectionally reinforced A1203 matrix composites have been fabricated by hot pressing. Approximately 30 volume % of either coated or uncoated sapphire fiber was used as reinforcement. Unstabilized ZrO2 was applied as the fiber coating. Composite mechanical behavior was analyzed both after fabrication and after additional heat treatment. The results of composite tensile tests were correlated with fiber-matrix interfacial shear strengths determined from fiber push-out tests. Substantially higher strength and greater fiber pull-out were observed for the coated fiber composites for all processing conditions studied. The coated fiber composites retained up to 95% and 87% of their as-fabricated strength when heat treated at 14000C for 8 or 24 hours, respectively. Electron microscopy analysis of the fracture surfaces revealed extensive fiber pull-out both before and after heat treatment.

Achieving food security for one million sub-Saharan African poor through push-pull innovation by 2020.

PubMed

Khan, Zeyaur R; Midega, Charles A O; Pittchar, Jimmy O; Murage, Alice W; Birkett, Michael A; Bruce, Toby J A; Pickett, John A

2014-04-05

Food insecurity is a chronic problem in Africa and is likely to worsen with climate change and population growth. It is largely due to poor yields of the cereal crops caused by factors including stemborer pests, striga weeds and degraded soils. A platform technology, 'push-pull', based on locally available companion plants, effectively addresses these constraints resulting in substantial grain yield increases. It involves intercropping cereal crops with a forage legume, desmodium, and planting Napier grass as a border crop. Desmodium repels stemborer moths (push), and attracts their natural enemies, while Napier grass attracts them (pull). Desmodium is very effective in suppressing striga weed while improving soil fertility through nitrogen fixation and improved organic matter content. Both companion plants provide high-value animal fodder, facilitating milk production and diversifying farmers' income sources. To extend these benefits to drier areas and ensure long-term sustainability of the technology in view of climate change, drought-tolerant trap and intercrop plants are being identified. Studies show that the locally commercial brachiaria cv mulato (trap crop) and greenleaf desmodium (intercrop) can tolerate long droughts. New on-farm field trials show that using these two companion crops in adapted push-pull technology provides effective control of stemborers and striga weeds, resulting in significant grain yield increases. Effective multi-level partnerships have been established with national agricultural research and extension systems, non-governmental organizations and other stakeholders to enhance dissemination of the technology with a goal of reaching one million farm households in the region by 2020. These will be supported by an efficient desmodium seed production and distribution system in eastern Africa, relevant policies and stakeholder training and capacity development.

Calibrating the interaction matrix for the LINC-NIRVANA high layer wavefront sensor.

PubMed

Zhang, Xianyu; Arcidiacono, Carmelo; Conrad, Albert R; Herbst, Thomas M; Gaessler, Wolfgang; Bertram, Thomas; Ragazzoni, Roberto; Schreiber, Laura; Diolaiti, Emiliano; Kuerster, Martin; Bizenberger, Peter; Meschke, Daniel; Rix, Hans-Walter; Rao, Changhui; Mohr, Lars; Briegel, Florian; Kittmann, Frank; Berwein, Juergen; Trowitzsch, Jan

2012-03-26

LINC-NIRVANA is a near-infrared Fizeau interferometric imager that will operate at the Large Binocular Telescope. In preparation for the commissioning of this instrument, we conducted experiments for calibrating the high-layer wavefront sensor of the layer-oriented multi-conjugate adaptive optics system. For calibrating the multi-pyramid wavefront sensor, four light sources were used to simulate guide stars. Using this setup, we developed the push-pull method for calibrating the interaction matrix. The benefits of this method over the traditional push-only method are quantified, and also the effects of varying the number of push-pull frames over which aberrations are averaged is reported. Finally, we discuss a method for measuring mis-conjugation between the deformable mirror and the wavefront sensor, and the proper positioning of the wavefront sensor detector with respect to the four pupil positions.

Choices of Destination for Transnational Higher Education: "Pull" Factors in an Asia Pacific Market

ERIC Educational Resources Information Center

Ahmad, Syed Zamberi; Buchanan, Frederick Robert

2016-01-01

Traditional assumptions favouring native English language countries in transnational higher education (TNHE) overlook experiences of international students in new emerging Asian education hubs. Specifically, there has been limited research relating to international students' choice for studying in Malaysia. Drawing from the "push-pull"…

Robotic Access to Planetary Surfaces Capability Roadmap

NASA Technical Reports Server (NTRS)

2005-01-01

A set of robotic access to planetary surfaces capability developments and supporting infrastructure have been identified. Reference mission pulls derived from ongoing strategic planning. Capability pushes to enable broader mission considerations. Facility and flight test capability needs. Those developments have been described to the level of detail needed for high-level planning. Content and approach. Readiness and metrics. Rough schedule and cost. Connectivity to mission concepts.

2005 5th Annual CMMI Technology Conference and User Group. Volume 3 - Wednesday

DTIC Science & Technology

2005-11-17

Product-Related Mistakes 28. Requirements gold-plating 29. Feature creep 30. Developer gold-plating 31. Push me, pull me negotiation 32. Research...STATE UNIVERSITY 14 IV&V Layer – Select Criticality Levels for IV&V Techniques using pull -down menus PORTLAND STATE UNIVERSITY 15...of time • Develop a proposal describing how to accomplish the goal and identifying what resources would be required Look for better solutions! • Pull

Identifying Advanced Technologies for Education's Future.

ERIC Educational Resources Information Center

Moore, Gwendolyn B.; Yin, Robert K.

A study to determine how three advanced technologies might be applied to the needs of special education students helped inspire the development of a new method for identifying such applications. This new method, named the "Hybrid Approach," combines features of the two traditional methods: technology-push and demand-pull. Technology-push involves…

Acceptor number-dependent ultrafast photo-physical properties of push-pull chromophores using time-resolved methods

NASA Astrophysics Data System (ADS)

Chi, Xiao-Chun; Wang, Ying-Hui; Gao, Yu; Sui, Ning; Zhang, Li-Quan; Wang, Wen-Yan; Lu, Ran; Ji, Wen-Yu; Yang, Yan-Qiang; Zhang, Han-Zhuang

2018-04-01

Three push-pull chromophores comprising a triphenylamine (TPA) as electron-donating moiety and functionalized β-diketones as electron acceptor units are studied by various spectroscopic techniques. The time-correlated single-photon counting data shows that increasing the number of electron acceptor units accelerates photoluminescence relaxation rate of compounds. Transient spectra data shows that intramolecular charge transfer (ICT) takes place from TPA units to β-diketones units after photo-excitation. Increasing the number of electron acceptor units would prolong the generation process of ICT state, and accelerate the excited molecule reorganization process and the relaxation process of ICT state.

Engineered microbes and methods for microbial oil production

DOEpatents

Stephanopoulos, Gregory; Tai, Mitchell; Chakraborty, Sagar

2015-02-10

Some aspects of this invention provide engineered microbes for oil production. Methods for microbe engineering and for use of engineered microbes are also provided herein. In some embodiments, microbes are provided that are engineered to modulate a combination of rate-controlling steps of lipid synthesis, for example, a combination of a step generating metabolites, acetyl-CoA, ATP or NADPH for lipid synthesis (a push step), and a step sequestering a product or an intermediate of a lipid synthesis pathway that mediates feedback inhibition of lipid synthesis (a pull step). Such push-and-pull engineered microbes exhibit greatly enhanced conversion yields and TAG synthesis and storage properties.

A centrifuge simulated push-pull manoeuvre with subsequent reduced +Gz tolerance.

PubMed

Xu, Yan; Li, Bao-Hui; Zhang, Li-Hui; Jin, Zhao; Wei, Xiao-Yang; Wang, Hong; Wu, San-Yuan; Wang, Hai-Xia; Wang, Quan; Yan, Gui-Ding; Deng, Lue; Geng, Xi-Chen

2012-07-01

The push-pull effect (PPE) has been recognized as a deleterious contributor to fatal flight accidents. The purpose of the study was to establish a push-pull manoeuvre (PPM) simulation with a tri-axes centrifuge, studying the effect of this PPM on the +Gz tolerance, and to make this simulation suitable for pilot centrifuge training. The PPM was realized through pre-programmed acceleration profiles consisting of -1 Gz for 5 s followed by a +Gz plateau for 10 s. Relaxed +Gz tolerance recordings were obtained from 20 healthy male fighter aircraft pilots and 6 healthy male volunteers through exposure to pre-programmed profiles with and without previous -1 Gz exposure. A statistically significant decrease in +Gz tolerance was seen in all subjects after -1 Gz for 5 s exposure, 0.87 ± 0.13 G in the volunteer group and 0.95 ± 0.25 G in the pilot group. The ear opacity pulse as a +Gz tolerance endpoint criterion was sometimes found to be unreliable during the PPM experiments. The simulated PPM in this study elicited a PPE, which was obvious from the significant reduction in +Gz tolerance. The PPM profile appears useful to be included in centrifuge training.

Mobile remote manipulator vehicle system

NASA Technical Reports Server (NTRS)

Bush, Harold G. (Inventor); Mikulas, Martin M., Jr. (Inventor); Wallsom, Richard E. (Inventor); Jensen, J. Kermit (Inventor)

1987-01-01

A mobile remote manipulator system is disclosed for assembly, repair and logistics transport on, around and about a space station square bay truss structure. The vehicle is supported by a square track arrangement supported by guide pins integral with the space station truss structure and located at each truss node. Propulsion is provided by a central push-pull drive mechanism that extends out from the vehicle one full structural bay over the truss and locks drive rods into the guide pins. The draw bar is now retracted and the mobile remote manipulator system is pulled onto the next adjacent structural bay. Thus, translation of the vehicle is inchworm style. The drive bar can be locked onto two guide pins while the extendable draw bar is within the vehicle and then push the vehicle away one bay providing bidirectional push-pull drive. The track switches allow the vehicle to travel in two orthogonal directions over the truss structure which coupled with the bidirectional drive, allow movement in four directions on one plane. The top layer of this trilayered vehicle is a logistics platform. This platform is capable of 369 degees of rotation and will have two astronaut foot restraint platforms and a space crane integral.

Theoretical study on the spectroscopic and third-order nonlinear optical properties of two-dimensional charge-transfer pyrazine derivatives

NASA Astrophysics Data System (ADS)

Li, Haipeng; Zhang, Yi; Bi, Zetong; Xu, Runfeng; Li, Mingxue; Shen, Xiaopeng; Tang, Gang; Han, Kui

2017-12-01

In this paper, density functional theory method was employed to study the electronic absorption spectrum and electronic static second hyperpolarisability of X-shaped pyrazine derivatives with two-dimensional charge-transfer structures. Computational results show that the push-pull electron abilities of the substituent groups and the length of the conjugated chains affect the electronic spectrum and static second hyperpolarisability of the pyrazine derivatives. As the push-pull electron abilities of the substituent groups or the length of the conjugated chains increases, the frontier molecular orbital energy gap decreases, resulting in increased second hyperpolarisability and redshift of the electronic absorption bands. The electronic absorption spectra of the pyrazine derivatives maintain good transparency in the blue light band. The electronic static second hyperpolarisability exhibits a linear relationship to the frontier molecular orbital energy gap. Particularly, increasing/decreasing the push-pull electron abilities of the substituent groups considerably affect the static second hyperpolarisability in long conjugated systems, which is important to the modulation of molecular organic nonlinear optical (NLO) properties. The studied pyrazine derivatives show large third-order NLO response and good transparency in the blue light band and are thus promising candidates as NLO materials for photonics applications.

History of United States Army physical fitness and physical readiness training.

PubMed

Knapik, Joseph J; East, Whitfield B

2014-01-01

This article traces the history of US Army physical fitness assessments from the first test developed for Cadets at the US Military Academy in 1858 through efforts to revise the current Army Physical Fitness Test (APFT). The first "Individual Efficiency Test" (1920) for all Soldiers consisted of a 100-yard run, running broad jump, wall climb, hand grenade throw, and obstacle course. The first scientific efforts involved testing of 400 Soldiers and a factor analysis of 25 individual test items. In 1944, this resulted in a 7-item test (pull-up, burpee, squat jump, push-up, man-carry, sit-up and 300-yard run) with a 100-point scoring system. In 1943, women were encouraged to take a "self-assessment" consisting of push-ups, bent knee sit-ups, wing lifts, squat thrusts, running, and a stork stand. In 1946, age-adjusted standards were introduced and in 1965 semiannual fitness assessments were mandated. The number of tests proliferated in the 1969-1973 period with 7 separate assessments. The current APFT consisting of push-ups, sit-ups, and a 2-mile run was introduced in 1980 and alternative tests for those with physical limitations in 1982. Current efforts to revise the assessment involve systematic literature reviews and validating the relationship between test items and common Soldiering tasks.

A Two-Magnet System to Push Therapeutic Nanoparticles

NASA Astrophysics Data System (ADS)

Shapiro, Benjamin; Dormer, Kenneth; Rutel, Isaac B.

2010-12-01

Magnetic fields can be used to direct magnetically susceptible nanoparticles to disease locations: to infections, blood clots, or tumors. Any single magnet always attracts (pulls) ferro- or para-magnetic particles towards it. External magnets have been used to pull therapeutics into tumors near the skin in animals and human clinical trials. Implanting magnetic materials into patients (a feasible approach in some cases) has been envisioned as a means of reaching deeper targets. Yet there are a number of clinical needs, ranging from treatments of the inner ear, to antibiotic-resistant skin infections and cardiac arrhythmias, which would benefit from an ability to magnetically "inject", or push in, nanomedicines. We develop, analyze, and experimentally demonstrate a novel, simple, and effective arrangement of just two permanent magnets that can magnetically push particles. Such a system might treat diseases of the inner ear; diseases which intravenously injected or orally administered treatments cannot reach due to the blood-brain barrier.

Standardizing Ammunition Distribution within the United States Navy as either a Push or Pull Methodology

DTIC Science & Technology

2012-06-01

office supplies, basic construction materials, soap or detergent, pasta , etc., will yield success within a push system because they will always have...Push Distribution The first corporation that will be reviewed is Barilla, Inc, which is the world’s largest pasta producer (Simchi-Levi et al...and free transportation if they ordered full truckloads of pasta , and sales representatives earned larger salaries and commissions based on the

Air Force Recoverable Central Leveling System (D)28): Retail Handbook

DTIC Science & Technology

1988-09-01

historical stuff.. .Just how its done and how is it affecting me today* (4). *It’s not an "asset push* system, its a * levels push’ system.’ *The system...consists primarily of a ’pull* system. For this same reason they lack under- standing why Tertain recoverables are under a ’ levels push’ type of system . 2...levels in the order the D028 system calculates as the highest marginal gain. Each recorded user will receive a * levels push’ of at least one, and all D028

A focus group study of predictors of relapse in electronic gaming machine problem gambling, part 2: factors that 'pull' the gambler away from relapse.

PubMed

Oakes, J; Pols, R; Battersby, M; Lawn, S; Pulvirenti, M; Smith, D

2012-09-01

This study aimed to develop an empirically based description of relapse in Electronic Gaming Machine (EGM) problem gambling (PG) by describing the processes and factors that 'pull' the problem gambler away from relapse contrasted with the 'push' towards relapse. These conceptualisations describe two opposing, interacting emotional processes occurring within the problem gambler during any relapse episode. Each relapse episode comprises a complex set of psychological and social behaviours where many factors interact sequentially and simultaneously within the problem gambler to produce a series of mental and behaviour events that end (1) with relapse where 'push' overcomes 'pull' or (2) continued abstinence where 'pull' overcomes 'push'. Four focus groups comprising thirty participants who were EGM problem gamblers, gamblers' significant others, therapists and counsellors described their experiences and understanding of relapse. The groups were recorded, recordings were then transcribed and analysed using thematic textual analysis. It was established that vigilance, motivation to commit to change, positive social support, cognitive strategies such as remembering past gambling harms or distraction techniques to avoid thinking about gambling to enable gamblers to manage the urge to gamble and urge extinction were key factors that protected against relapse. Three complementary theories emerged from the analysis. Firstly, a process of reappraisal of personal gambling behaviour pulls the gambler away from relapse. This results in a commitment to change that develops over time and affects but is independent of each episode of relapse. Secondly, relapse may be halted by interacting factors that 'pull' the problem gambler away from the sequence of mental and behavioural events, which follow the triggering of the urge and cognitions to gamble. Thirdly, urge extinction and apparent 'cure' is possible for EGM gambling. This study provides a qualitative, empirical model for understanding protective factors against gambling relapse.

Benefit of "Push-pull" Locomotion for Planetary Rover Mobility

NASA Technical Reports Server (NTRS)

Creager, Colin M.; Moreland, Scott Jared; Skonieczny, K.; Johnson, K.; Asnani, V.; Gilligan, R.

2011-01-01

As NASAs exploration missions on planetary terrains become more aggressive, a focus on alternative modes of locomotion for rovers is necessary. In addition to climbing steep slopes, the terrain in these extreme environments is often unknown and can be extremely hard to traverse, increasing the likelihood of a vehicle or robot becoming damaged or immobilized. The conventional driving mode in which all wheels are either driven or free-rolling is very efficient on flat hard ground, but does not always provide enough traction to propel the vehicle through soft or steep terrain. This paper presents an alternative mode of travel and investigates the fundamental differences between these locomotion modes. The methods of push-pull locomotion discussed can be used with articulated wheeled vehicles and are identified as walking or inchinginch-worming. In both cases, the braked non-rolling wheels provide increased thrust. An in-depth study of how soil reacts under a rolling wheel vs. a braked wheel was performed by visually observing the motion of particles beneath the surface. This novel technique consists of driving or dragging a wheel in a soil bin against a transparent wall while high resolution, high-rate photographs are taken. Optical flow software was then used to determine shearing patterns in the soil. Different failure modes were observed for the rolling and braked wheel cases. A quantitative comparison of inching vs. conventional driving was also performed on a full-scale vehicle through a series of drawbar pull tests in the Lunar terrain strength simulant, GRC-1. The effect of tire stiffness was also compared; typically compliant tires provide better traction when driving in soft soil, however its been observed that rigid wheels may provide better thrust when non-rolling. Initial tests indicate up to a possible 40 increase in pull force capability at high slip when inching vs. rolling.

Baldrige Theory into Practice: A Generic Model

ERIC Educational Resources Information Center

Arif, Mohammed

2007-01-01

Purpose: The education system globally has moved from a push-based or producer-centric system to a pull-based or customer centric system. Malcolm Baldrige Quality Award (MBQA) model happens to be one of the latest additions to the pull based models. The purpose of this paper is to develop a generic framework for MBQA that can be used by…

Proceedings of the Annual Conference on Technology and Innovations in Training and Education (9th)

DTIC Science & Technology

1991-01-01

training features. Figure 15 illustrates community well. The push and the training system features pull of interactivity, as well analysis process. Note that...offers a restructuring of its staff to balance the number of pull down menus that enable a user to easily create technical staff members with the...Merlin lessons using a series of "preformatted templates" Objetive number which negates the need to actually use Merlin code. It offers pull down menus

An improved push-pull voltage fed converter using a tapped output-filter inductor

NASA Technical Reports Server (NTRS)

Wester, G. W.

1983-01-01

A new concept of using a tapped output-filter inductor and an auxiliary commutating diode to reduce the likelihood of transformer core saturation in a push-pull, voltage-fed converter is presented. The linearized circuit model and transfer functions are derived with a hybrid approach using both state-space and circuit averaging. Operation of the new converter - including parasitic effects - is discussed, and a design equation for inductor tap ratio is established. It is predicted and experimentally confirmed that the new converter has more symmetrical transformer core operation, and the potential exits for lower transistor turnon current and reduced transistor voltage stress. These benefits reduce switching loss and enhance transistor reliability.

Diffraction analysis and evaluation of several focus- and track-error detection schemes for magneto-optical disk systems

NASA Technical Reports Server (NTRS)

Bernacki, Bruce E.; Mansuripur, M.

1992-01-01

A commonly used tracking method on pre-grooved magneto-optical (MO) media is the push-pull technique, and the astigmatic method is a popular focus-error detection approach. These two methods are analyzed using DIFFRACT, a general-purpose scalar diffraction modeling program, to observe the effects on the error signals due to focusing lens misalignment, Seidel aberrations, and optical crosstalk (feedthrough) between the focusing and tracking servos. Using the results of the astigmatic/push-pull system as a basis for comparison, a novel focus/track-error detection technique that utilizes a ring toric lens is evaluated as well as the obscuration method (focus error detection only).

Engineered microbes and methods for microbial oil production

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

Stephanopoulos, Gregory; Tai, Mitchell; Chakraborty, Sagar

Some aspects of this invention provide engineered microbes for oil production. Methods for microbe engineering and for use of engineered microbes are also provided herein. In some embodiments, microbes are provided that are engineered to modulate a combination of rate-controlling steps of lipid synthesis, for example, a combination of a step generating metabolites, acetyl-CoA, ATP or NADPH for lipid synthesis (a push step), and a step sequestering a product or an intermediate of a lipid synthesis pathway that mediates feedback inhibition of lipid synthesis (a pull step). Such push-and-pull engineered microbes exhibit greatly enhanced conversion yields and TAG synthesis andmore » storage properties.« less

Influence of trabecular bone quality and implantation direction on press-fit mechanics.

PubMed

Damm, Niklas B; Morlock, Michael M; Bishop, Nicholas E

2017-02-01

Achieving primary stability of uncemented press-fit prostheses in patients with poor quality bone can involve axial implantation forces large enough to cause bone fracture. Radial implantation eliminates intraoperative impaction forces and could prevent this damage. Platens of two commercial implant surfaces ("Beaded" and "Flaked") were implanted onto trabecular bone specimens of varying quality in a press-fit simulator. Samples were implanted with varying interference, either axially (shear) or radially (normal). Push-in and pull-out forces were measured to assess stability. Microstructural changes in the bone were determined from μCT analysis. For force-defined implantation analysis, push-in and pull-out forces both increased proportionally with increasing radial force, independent of implantation direction, bone quality or implant surface. For position-defined implantation analysis, pull-out forces were generally found to increase with interference and to be greater for radial than axial implantation direction, and to be lower for poor quality bone. Bone density increased locally at the tested interface due to implantation, in particular for the Beaded surface under axial implantation. If a safe radial stress can be determined for cortical bone in a particular patient, the associated implantation force, and pull-out force which represents primary stability, can be directly derived, regardless of implantation direction, bone quality or implant surface. Radial implantation delivers primary stability that is no worse than that for axial implantation and may eliminate potentially damaging impaction forces. Development of implant designs based on this principal might improve implant fixation. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:224-233, 2017. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

R&D incentives for neglected diseases.

PubMed

Dimitri, Nicola

2012-01-01

Neglected diseases are typically characterized as those for which adequate drug treatment is lacking, and the potential return on effort in research and development (R&D), to produce new therapies, is too small for companies to invest significant resources in the field. In recent years various incentives schemes to stimulate R&D by pharmaceutical firms have been considered. Broadly speaking, these can be classified either as 'push' or 'pull' programs. Hybrid options, that include push and pull incentives, have also become increasingly popular. Supporters and critics of these various incentive schemes have argued in favor of their relative merits and limitations, although the view that no mechanism is a perfect fit for all situations appears to be widely held. For this reason, the debate on the advantages and disadvantages of different approaches has been important for policy decisions, but is dispersed in a variety of sources. With this in mind, the aim of this paper is to contribute to the understanding of the economic determinants behind R&D investments for neglected diseases by comparing the relative strength of different incentive schemes within a simple economic model, based on the assumption of profit maximizing firms. The analysis suggests that co-funded push programs are generally more efficient than pure pull programs. However, by setting appropriate intermediate goals hybrid incentive schemes could further improve efficiency.

Electrochemical push-pull probe: from scanning electrochemical microscopy to multimodal altering of cell microenvironment.

PubMed

Bondarenko, Alexandra; Cortés-Salazar, Fernando; Gheorghiu, Mihaela; Gáspár, Szilveszter; Momotenko, Dmitry; Stanica, Luciana; Lesch, Andreas; Gheorghiu, Eugen; Girault, Hubert H

2015-04-21

To understand biological processes at the cellular level, a general approach is to alter the cells' environment and to study their chemical responses. Herein, we present the implementation of an electrochemical push-pull probe, which combines a microfluidic system with a microelectrode, as a tool for locally altering the microenvironment of few adherent living cells by working in two different perturbation modes, namely electrochemical (i.e., electrochemical generation of a chemical effector compound) and microfluidic (i.e., infusion of a chemical effector compound from the pushing microchannel, while simultaneously aspirating it through the pulling channel, thereby focusing the flow between the channels). The effect of several parameters such as flow rate, working distance, and probe inclination angle on the affected area of adherently growing cells was investigated both theoretically and experimentally. As a proof of concept, localized fluorescent labeling and pH changes were purposely introduced to validate the probe as a tool for studying adherent cancer cells through the control over the chemical composition of the extracellular space with high spatiotemporal resolution. A very good agreement between experimental and simulated results showed that the electrochemical perturbation mode enables to affect precisely only a few living cells localized in a high-density cell culture.

Push-Pull Receptive Field Organization and Synaptic Depression: Mechanisms for Reliably Encoding Naturalistic Stimuli in V1

PubMed Central

Kremkow, Jens; Perrinet, Laurent U.; Monier, Cyril; Alonso, Jose-Manuel; Aertsen, Ad; Frégnac, Yves; Masson, Guillaume S.

2016-01-01

Neurons in the primary visual cortex are known for responding vigorously but with high variability to classical stimuli such as drifting bars or gratings. By contrast, natural scenes are encoded more efficiently by sparse and temporal precise spiking responses. We used a conductance-based model of the visual system in higher mammals to investigate how two specific features of the thalamo-cortical pathway, namely push-pull receptive field organization and fast synaptic depression, can contribute to this contextual reshaping of V1 responses. By comparing cortical dynamics evoked respectively by natural vs. artificial stimuli in a comprehensive parametric space analysis, we demonstrate that the reliability and sparseness of the spiking responses during natural vision is not a mere consequence of the increased bandwidth in the sensory input spectrum. Rather, it results from the combined impacts of fast synaptic depression and push-pull inhibition, the later acting for natural scenes as a form of “effective” feed-forward inhibition as demonstrated in other sensory systems. Thus, the combination of feedforward-like inhibition with fast thalamo-cortical synaptic depression by simple cells receiving a direct structured input from thalamus composes a generic computational mechanism for generating a sparse and reliable encoding of natural sensory events. PMID:27242445

Ring-push metric learning for person reidentification

NASA Astrophysics Data System (ADS)

He, Botao; Yu, Shaohua

2017-05-01

Person reidentification (re-id) has been widely studied because of its extensive use in video surveillance and forensics applications. It aims to search a specific person among a nonoverlapping camera network, which is highly challenging due to large variations in the cluttered background, human pose, and camera viewpoint. We present a metric learning algorithm for learning a Mahalanobis distance for re-id. Generally speaking, there exist two forces in the conventional metric learning process, one pulling force that pulls points of the same class closer and the other pushing force that pushes points of different classes as far apart as possible. We argue that, when only a limited number of training data are given, forcing interclass distances to be as large as possible may drive the metric to overfit the uninformative part of the images, such as noises and backgrounds. To alleviate overfitting, we propose the ring-push metric learning algorithm. Different from other metric learning methods that only punish too small interclass distances, in the proposed method, both too small and too large inter-class distances are punished. By introducing the generalized logistic function as the loss, we formulate the ring-push metric learning as a convex optimization problem and utilize the projected gradient descent method to solve it. The experimental results on four public datasets demonstrate the effectiveness of the proposed algorithm.

Assessment of a Geothermal Doublet in the Malm Aquifer Using a Push-Pull Tracer Test

NASA Astrophysics Data System (ADS)

Lafogler, Mark; Somogyi, Gabriella; Nießner, Reinhard; Baumann, Thomas

2013-04-01

Geothermal exploration of the Malm aquifer in Bavaria is highly successful. Data about the long-term operation, however, is still scarce, although detailed knowledge about the processes occurring in the aquifer is a key requirement to run geothermal facilities efficiently and economically. While there usually is a constant flow of data from the production well (temperatures, hydraulic data, hydrochemical conditions, gas composition) not even the temperatures in the immediate surrounding of the reinjection well are accessible or known. In 2011 the geothermal facility in Pullach was extended with a third geothermal well reaching into the Malm aquifer which is now used as a reinjection well. The former reinjection well was converted to a production well after 5 years of operation. This setting offers a unique opportunity to study the processes in the vicinity of a reinjection well and provides the data base to describe the hydraulic, thermal and hydrochemical performance of the reservoir. The viscosity of the reinjected cold water is increasing by 60% compared to the production well, thus one would expect an increase of the reinjection pressure as the cold water plume spreads around the reinjection well. Measurements, however, show a significant decrease of the reinjection pressure, suggesting processes in the aquifer which positively change the hydraulic properties and overcompensate the viscosity effects. Hydrochemical data and modeling indicate that a dissolution of the matrix along the flow pathways is responsible for the decreasing reinjection pressures. The change of the flow direction from reinjection to production was used to conduct a push-pull tracer test. Here, a series of fluorescent dye pulses was added to the reinjected water before the former reinjection well was shut down (push phase). These tracers included a conservative tracer (Fluorescein), surface-sensitive tracers (Eosin/Sulforhodamin B), and a NAPL-sensitive tracer (Na-Naphthionate). After changing to production mode in October 2012 the pull phase was started. The different behavior of the tracers within the reservoir delivers data about dispersion, sorption properties, matrix interaction and the regional flux. First tracer breakthrough curves point to a significant heterogeneity of the flow pathways and that regional flow is not negligible.

Insights about transport mechanisms and fracture flow channeling from multi-scale observations of tracer dispersion in shallow fractured crystalline rock.

PubMed

Guihéneuf, N; Bour, O; Boisson, A; Le Borgne, T; Becker, M W; Nigon, B; Wajiduddin, M; Ahmed, S; Maréchal, J-C

2017-11-01

In fractured media, solute transport is controlled by advection in open and connected fractures and by matrix diffusion that may be enhanced by chemical weathering of the fracture walls. These phenomena may lead to non-Fickian dispersion characterized by early tracer arrival time, late-time tailing on the breakthrough curves and potential scale effect on transport processes. Here we investigate the scale dependency of these processes by analyzing a series of convergent and push-pull tracer experiments with distance of investigation ranging from 4m to 41m in shallow fractured granite. The small and intermediate distances convergent experiments display a non-Fickian tailing, characterized by a -2 power law slope. However, the largest distance experiment does not display a clear power law behavior and indicates possibly two main pathways. The push-pull experiments show breakthrough curve tailing decreases as the volume of investigation increases, with a power law slope ranging from -3 to -2.3 from the smallest to the largest volume. The multipath model developed by Becker and Shapiro (2003) is used here to evaluate the hypothesis of the independence of flow pathways. The multipath model is found to explain the convergent data, when increasing local dispersivity and reducing the number of pathways with distance which suggest a transition from non-Fickian to Fickian transport at fracture scale. However, this model predicts an increase of tailing with push-pull distance, while the experiments show the opposite trend. This inconsistency may suggest the activation of cross channel mass transfer at larger volume of investigation, which leads to non-reversible heterogeneous advection with scale. This transition from independent channels to connected channels when the volume of investigation increases suggest that both convergent and push-pull breakthrough curves can inform the existence of characteristic length scales. Copyright © 2017 Elsevier B.V. All rights reserved.

Push-pull training reduces foveal sensory eye dominance within the early visual channels

PubMed Central

Xu, Jingping P.; He, Zijiang J.; Ooi, Teng Leng

2011-01-01

A push-pull training protocol is applied to reduce sensory eye dominance in the foveal region. The training protocol consists of cueing the weak eye to force it to become dominant while the strong eye is suppressed when a pair of dichoptic orthogonal grating stimulus is subsequently presented to it (Ooi and He, 1999). We trained with four pairs of dichoptic orthogonal gratings (0°/90°, 90°/0°, 45°/135° and 135°/45° at 3 cpd) to affect the interocular inhibitory interaction tuned to the four trained orientations (0°, 45°, 90° and 135°). After a 10-day training session, we found a significant learning effect (reduced sensory eye dominance) at the trained orientations as well as at two other untrained orientations (22.5° and 67.5°). This suggests that the four pairs of oriented training stimuli are sufficient to produce a learning effect at any other orientation. The nearly complete transfer of the learning effect across orientation is attributed to the fact that the trained and untrained orientations are close enough to fall in the same orientation tuning function of the early visual cortical neurons (~37.5°). Applying the same notion of transfer of learning within the same feature channel, we also found a large transfer effect to an untrained spatial frequency (6 cpd), which is 1 octave higher than the trained spatial frequency (3 cpd). Furthermore, we found that stereopsis is improved, as is the competitive ability between the two eyes, after the push-pull training. Our data analysis suggests that these improvements are correlated with the reduced sensory eye dominance after the training, i.e., due to a more balanced interocular inhibition. We also found that the learning effect (reduced SED and stereo threshold) can be retained for more than a year after the termination of the push-pull training. PMID:21689673

Insights about transport mechanisms and fracture flow channeling from multi-scale observations of tracer dispersion in shallow fractured crystalline rock

NASA Astrophysics Data System (ADS)

Guihéneuf, N.; Bour, O.; Boisson, A.; Le Borgne, T.; Becker, M. W.; Nigon, B.; Wajiduddin, M.; Ahmed, S.; Maréchal, J.-C.

2017-11-01

In fractured media, solute transport is controlled by advection in open and connected fractures and by matrix diffusion that may be enhanced by chemical weathering of the fracture walls. These phenomena may lead to non-Fickian dispersion characterized by early tracer arrival time, late-time tailing on the breakthrough curves and potential scale effect on transport processes. Here we investigate the scale dependency of these processes by analyzing a series of convergent and push-pull tracer experiments with distance of investigation ranging from 4 m to 41 m in shallow fractured granite. The small and intermediate distances convergent experiments display a non-Fickian tailing, characterized by a -2 power law slope. However, the largest distance experiment does not display a clear power law behavior and indicates possibly two main pathways. The push-pull experiments show breakthrough curve tailing decreases as the volume of investigation increases, with a power law slope ranging from - 3 to - 2.3 from the smallest to the largest volume. The multipath model developed by Becker and Shapiro (2003) is used here to evaluate the hypothesis of the independence of flow pathways. The multipath model is found to explain the convergent data, when increasing local dispersivity and reducing the number of pathways with distance which suggest a transition from non-Fickian to Fickian transport at fracture scale. However, this model predicts an increase of tailing with push-pull distance, while the experiments show the opposite trend. This inconsistency may suggest the activation of cross channel mass transfer at larger volume of investigation, which leads to non-reversible heterogeneous advection with scale. This transition from independent channels to connected channels when the volume of investigation increases suggest that both convergent and push-pull breakthrough curves can inform the existence of characteristic length scales.

An Overview of Direct Push Technology

DTIC Science & Technology

1994-08-12

Figure 3.4). Zemo et. al. (1992) indicate this probe is first pushed to the target zone, then pulled up to open the screened section in 27 the same manner...28 * manufactured by QED Environmental Systems (Figure 3.5). Zemo et. al. (1992) indicate this sampler is also pushed to the required depth, then...Exhibition, HMC/Superfund, pp. 228-237, Dec. 1-3, 1992, Washington, D.C. Zemo , D. A., Delfino, J. D., Gallinatti, J. D., Baker, V. A., and Hilpert, L. R

A minimal model for kinetochore-microtubule dynamics

NASA Astrophysics Data System (ADS)

Liu, Andrea

2014-03-01

During mitosis, chromosome pairs align at the center of a bipolar microtubule (MT) spindle and oscillate as MTs attaching them to the cell poles polymerize and depolymerize. The cell fixes misaligned pairs by a tension-sensing mechanism. Pairs later separate as shrinking MTs pull each chromosome toward its respective cell pole. We present a minimal model for these processes based on properties of MT kinetics. We apply the measured tension-dependence of single MT kinetics to a stochastic many MT model, which we solve numerically and with master equations. We find that the force-velocity curve for the single chromosome system is bistable and hysteretic. Above some threshold load, tension fluctuations induce MTs to spontaneously switch from a pulling state into a growing, pushing state. To recover pulling from the pushing state, the load must be reduced far below the threshold. This leads to oscillations in the two-chromosome system. Our minimal model quantitatively captures several aspects of kinetochore dynamics observed experimentally. This work was supported by NSF-DMR-1104637.

Comprehensive manual handling limits for lowering, pushing, pulling and carrying activities.

PubMed

Shoaf, C; Genaidy, A; Karwowski, W; Waters, T; Christensen, D

1997-11-01

The objective of this study was to develop a set of mathematical models for manual lowering, pushing, pulling and carrying activities that would result in establishing load capacity limits to protect the lower back against occupational low-back disorders. In order to establish safe guidelines, a three-stage process was used. First, psychophysical data was used to generate the models' discounting factors and recommended load capacities. Second, biomechanical analysis was used to refine the recommended load capacities. Third, physiological criteria were used to validate the models' discounting factors. Both task and personal factors were considered in the models' development. When compared to the results from prior psychophysical research for these activities, the developed load capacity values are lower than previously established limits. The results of this study allowed the authors to validate the hypothesis proposed and tested by Karwowski (1983) that states that the combination of physiological and biomechanical stresses should lead to the overall measure of task acceptability or the psychophysical stress. This study also found that some of the discounting factors for the task frequency parameters recommended in the prior psychophysical research should not be used as several of the high frequency factors violated physiological limits.

Push-Pull: Chemical Ecology-Based Integrated Pest Management Technology.

PubMed

Khan, Zeyaur; Midega, Charles A O; Hooper, Antony; Pickett, John

2016-07-01

Lepidopterous stemborers, and parasitic striga weeds belonging to the family Orobanchaceae, attack cereal crops in sub-Saharan Africa causing severe yield losses. The smallholder farmers are resource constrained and unable to afford expensive chemicals for crop protection. The push-pull technology, a chemical ecology- based cropping system, is developed for integrated pest and weed management in cereal-livestock farming systems. Appropriate plants were selected that naturally emit signaling chemicals (semiochemicals). Plants highly attractive for stemborer egg laying were selected and employed as trap crops (pull), to draw pests away from the main crop. Plants that repelled stemborer females were selected as intercrops (push). The stemborers are attracted to the trap plant, and are repelled from the main cereal crop using a repellent intercrop (push). Root exudates of leguminous repellent intercrops also effectively control the parasitic striga weed through an allelopathic mechanism. Their root exudates contain flavonoid compounds some of which stimulate germination of Striga hermonthica seeds, such as Uncinanone B, and others that dramatically inhibit their attachment to host roots, such as Uncinanone C and a number of di-C-glycosylflavones (di-CGFs), resulting in suicidal germination. The intercrop also improves soil fertility through nitrogen fixation, natural mulching, improved biomass, and control of erosion. Both companion plants provide high value animal fodder, facilitating milk production and diversifying farmers' income sources. The technology is appropriate to smallholder mixed cropping systems in Africa. Adopted by about 125,000 farmers to date in eastern Africa, it effectively addresses major production constraints, significantly increases maize yields, and is economical as it is based on locally available plants, not expensive external inputs.

Contact irritant responses of Aedes aegypti Using sublethal concentration and focal application of pyrethroid chemicals.

PubMed

Manda, Hortance; Shah, Pankhil; Polsomboon, Suppaluck; Chareonviriyaphap, Theeraphap; Castro-Llanos, Fanny; Morrison, Amy; Burrus, Roxanne G; Grieco, John P; Achee, Nicole L

2013-01-01

Previous studies have demonstrated contact irritant and spatial repellent behaviors in Aedes aegypti following exposure to sublethal concentrations of chemicals. These sublethal actions are currently being evaluated in the development of a push-pull strategy for Ae. aegypti control. This study reports on mosquito escape responses after exposure to candidate chemicals for a contact irritant focused push-pull strategy using varying concentrations and focal application. Contact irritancy (escape) behavior, knockdown and 24 hour mortality rates were quantified in populations of female Ae. aegypti under laboratory conditions and validated in the field (Thailand and Peru) using experimental huts. Evaluations were conducted using varying concentrations and treatment surface area coverage (SAC) of three pyrethroid insecticides: alphacypermethrin, lambacyhalothrin and deltamethrin. Under laboratory conditions, exposure of Ae. aegypti to alphacypermethrin using the standard field application rate (FAR) resulted in escape responses at 25% and 50% SAC that were comparable with escape responses at 100% SAC. Significant escape responses were also observed at <100% SAC using ½FAR of all test compounds. In most trials, KD and 24 hour mortality rates were higher in mosquitoes that did not escape than in those that escaped. In Thailand, field validation studies indicated an early time of exit (by four hours) and 40% increase in escape using ½FAR of alphacypermethrin at 75% SAC compared to a matched chemical-free control. In Peru, however, the maximum increase in Ae. aegypti escape from alphacypermethrin-treated huts was 11%. Results presented here suggest a potential role for sublethal and focal application of contact irritant chemicals in an Ae. aegypti push-pull strategy to reduce human-vector contact inside treated homes. However, the impact of an increase in escape response on dengue virus transmission is currently unknown and will depend on rate of biting on human hosts prior to house exiting.

Laser pushing or pulling of absorbing airborne particles

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

Wang, Chuji, E-mail: cw175@msstate.edu; Gong, Zhiyong; Pan, Yong-Le

2016-07-04

A single absorbing particle formed by carbon nanotubes in the size range of 10–50 μm is trapped in air by a laser trapping beam and concurrently illuminated by another laser manipulating beam. When the trapping beam is terminated, the movement of the particle controlled by the manipulating beam is investigated. We report our observations of light-controlled pushing and pulling motions. We show that the movement direction has little relationship with the particle size and manipulating beam's parameters but is dominated by the particle's orientation and morphology. With this observation, the controllable optical manipulation is now able to be generalized to arbitrarymore » particles, including irregularly shaped absorbing particles that are shown in this work.« less

Strategies of Production Control as Tools of Efficient Management of Production Enterprises

NASA Astrophysics Data System (ADS)

Budynek, Mateusz; Celińska, Elżbieta; Dybikowska, Adrianna; Kozak, Monika; Ratajczak, Joanna; Urban, Jagoda; Materne, Karolina

2016-03-01

The paper discusses the problem of principle methods of production control as a strategy supporting the production system and stimulating efficient solutions in respect management in production enterprises. The article describes MRP, ERP, JIT, KANBAN and TOC methods and focuses on their main goals, principles of functioning as well as benefits resulting from their application. The methods represent two diverse strategies of production control, i.e. pull and push strategies. Push strategies are used when the plans apply to the first and principle part of production and are based on the demand forecasts. Pull strategies are used when all planning decisions apply to the final stage and depend on the actual demand or orders from customers.

Adult Literacy in Africa: The Push and Pull Factors

NASA Astrophysics Data System (ADS)

Omolewa, Michael

2008-11-01

This paper examines the question of why Africa has made such slow progress towards the goal of eradicating illiteracy, and why it remains an exceptionally disadvantaged region in this respect. The article surveys the history of the development of literacy in Africa from colonial times to the present day, focusing on the role of adult education in pursuing the goal of universal literacy. The author seeks to identify both the "push" factors (those favouring the pursuit of this goal) and the "pull" factors (the obstacles and hindrances), examining these factors at the local, national and international levels. The author concludes that, while the literacy challenge in Africa remains a formidable one, there are examples of successful initiatives that give hope for the future.

The Narrowing of Knowing: What It Means to Be Literate and Learned in Today's Society

ERIC Educational Resources Information Center

Smith, Thomas

2008-01-01

Currently, the idea and definition of learning and literacy is being pushed and pulled in competing directions. Current governmental policies, most notably embodied in the No Child Left Behind law, are pushing the definitions to mechanical enterprises aimed at the lowest common denominator. At the same time, the technology race is working to open…

Exploring a QoS Driven Scheduling Approach for Peer-to-Peer Live Streaming Systems with Network Coding

PubMed Central

Cui, Laizhong; Lu, Nan; Chen, Fu

2014-01-01

Most large-scale peer-to-peer (P2P) live streaming systems use mesh to organize peers and leverage pull scheduling to transmit packets for providing robustness in dynamic environment. The pull scheduling brings large packet delay. Network coding makes the push scheduling feasible in mesh P2P live streaming and improves the efficiency. However, it may also introduce some extra delays and coding computational overhead. To improve the packet delay, streaming quality, and coding overhead, in this paper are as follows. we propose a QoS driven push scheduling approach. The main contributions of this paper are: (i) We introduce a new network coding method to increase the content diversity and reduce the complexity of scheduling; (ii) we formulate the push scheduling as an optimization problem and transform it to a min-cost flow problem for solving it in polynomial time; (iii) we propose a push scheduling algorithm to reduce the coding overhead and do extensive experiments to validate the effectiveness of our approach. Compared with previous approaches, the simulation results demonstrate that packet delay, continuity index, and coding ratio of our system can be significantly improved, especially in dynamic environments. PMID:25114968

The macrodynamics of international migration as a sociocultural diffusion process. Part A: theory.

PubMed

Diamantides, N D

1992-11-01

"This study formulates a model of the macrodynamics of international migration using a differential equation to capture the push-pull forces that propel it. The model's architecture rests on the functioning of information feedback between settled friends and family at the destination and potential emigrants at the origin." The author tests the model using data on Greek emigration to the United States since 1820 and on total emigration from Cyprus since 1946. excerpt

Remote Munitions Deployment from an Unmanned Ground Vehicle

DTIC Science & Technology

2011-08-09

pack in a series of toe lugs. Then the rear of the pack is pushed downward over a novel spring-loaded latch /release mechanism, remaining locked in...Mason, Patrick R. Griffin, Charles E. Dean Page 4 of 5 UNCLASSIFIED developments and testing, it is not secured by a latch /release mechanism...However, the locating tabs act to wedge the pack in place while still allowing it to pull free during launch. Figure 6: Munitions secured and

Pulling a Door Open by Pushing on It

ERIC Educational Resources Information Center

van den Berg, Willem H.

2007-01-01

Ordinarily, opening a door by pulling on the knob or handle causes a net torque on the door, and hence an angular acceleration, about a "vertical" axis. However, it may be that the top or bottom of the door sticks to the door frame; this horizontal force perpendicular to the plane of the door causes a torque on the door about a "horizontal" axis.…

Modular Electron Donor Group Tuning Of Frontier Energy Levels In Diarylaminofluorenone Push-Pull Molecules

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

Homnick, Paul J.; Lahti, P. M.

2012-01-01

Push–pull organic molecules composed of electron donor diarylamines at the 2- and 2,7-positions of fluorenone exhibit intramolecular charge-transfer behaviour in static absorption and emission spectra. Electrochemical and spectral data combined in a modular electronic analysis model show how the donor HOMO and acceptor LUMO act as major determinants of the frontier molecular orbital energy levels.

Effective Elastic and Neutron Capture Cross Section Calculations Corresponding to Simulated Fluid Properties from CO2 Push-Pull Simulations

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

Chugunov, Nikita; Altundas, Bilgin

The submission contains a .xls files consisting of 10 excel sheets, which contain combined list of pressure, saturation, salinity, temperature profiles from the simulation of CO2 push-pull using Brady reservoir model and the corresponding effective compressional and shear velocity, bulk density, and fluid and time-lapse neutron capture cross section profiles of rock at times 0 day (baseline) through 14 days. First 9 sheets (each named after the corresponding CO2 push-pull simulation time) contains simulated pressure, saturation, temperature, salinity profiles and the corresponding effective elastic and neutron capture cross section profiles of rock matrix at the time of CO2 injection. Eachmore » sheet contains two sets of effective compressional velocity profiles of the rock, one based on Gassmann and the other based on Patchy saturation model. Effective neutron capture cross section calculations are done using a proprietary neutron cross-section simulator (SNUPAR) whereas for the thermodynamic properties of CO2 and bulk density of rock matrix filled with fluid, a standalone fluid substitution tool by Schlumberger is used. Last sheet in the file contains the bulk modulus of solid rock, which is inverted from the rock properties (porosity, sound speed etc) based on Gassmann model. Bulk modulus of solid rock in turn is used in the fluid substitution.« less

Increased Release of Serotonin in the Spinal Cord During Low, But Not High, Frequency Transcutaneous Electric Nerve Stimulation in Rats With Joint Inflammation

PubMed Central

Sluka, Kathleen A.; Lisi, Tammy L.; Westlund, Karin N.

2009-01-01

Objective To determine the release pattern of serotonin and noradrenaline in the spinal cord in response to transcutaneous electric nerve stimulation (TENS) delivered at low or high frequency. Design Prospective randomized allocation of 3 treatments. Setting Research laboratory. Animals Male Sprague-Dawley rats (weight range, 250–350g). Intervention Knee joints of rats were inflamed with a mixture of 3% carrageenan and 3% kaolin for 24 hours prior to placement of push-pull cannulae into the dorsal horn of the spinal cord. Push-pull samples were collected in 10-minute intervals before, during, and after treatment with low-frequency TENS (4Hz), high-frequency TENS (100Hz), or sham TENS. TENS was applied to the inflamed knee joint for 20 minutes at sensory intensity and 100-μs pulse duration. Push-pull samples were analyzed for serotonin and noradrenaline by high performance liquid chromatography with coulemetric detection. Main Outcome Measures Spinal concentrations of serotonin and noradrenaline. Results Low-frequency TENS significantly increased serotonin concentrations during and immediately after treatment. There was no change in serotonin with high-frequency TENS, nor was there a change in noradrenaline with low- or high-frequency TENS. Conclusions Low-frequency TENS releases serotonin in the spinal cord to produce antihyperalgesia by activation of serotonin receptors. PMID:16876561

On the automatic link between affect and tendencies to approach and avoid: Chen and Bargh (1999) revisited

PubMed Central

Rotteveel, Mark; Gierholz, Alexander; Koch, Gijs; van Aalst, Cherelle; Pinto, Yair; Matzke, Dora; Steingroever, Helen; Verhagen, Josine; Beek, Titia F.; Selker, Ravi; Sasiadek, Adam; Wagenmakers, Eric-Jan

2015-01-01

Within the literature on emotion and behavioral action, studies on approach-avoidance take up a prominent place. Several experimental paradigms feature successful conceptual replications but many original studies have not yet been replicated directly. We present such a direct replication attempt of two seminal experiments originally conducted by Chen and Bargh (1999). In their first experiment, participants affectively evaluated attitude objects by pulling or pushing a lever. Participants who had to pull the lever with positively valenced attitude objects and push the lever with negatively valenced attitude objects (i.e., congruent instruction) did so faster than participants who had to follow the reverse (i.e., incongruent) instruction. In Chen and Bargh's second experiment, the explicit evaluative instructions were absent and participants merely responded to the attitude objects by either always pushing or always pulling the lever. Similar results were obtained as in Experiment 1. Based on these findings, Chen and Bargh concluded that (1) attitude objects are evaluated automatically; and (2) attitude objects automatically trigger a behavioral tendency to approach or avoid. We attempted to replicate both experiments and failed to find the effects reported by Chen and Bargh as indicated by our pre-registered Bayesian data analyses; nevertheless, the evidence in favor of the null hypotheses was only anecdotal, and definitive conclusions await further study. PMID:25883572

Future War: An Assessment of Aerospace Campaigns in 2010,

DTIC Science & Technology

1996-01-01

theoretician: "The impending sixth generation of warfare, with its centerpiece of superior data-processing to support precision smart weaponry, will radically...tions concept of " smart push, warrior pull." If JFACC were colocated with the worldwide intelligence manager, unit taskings and the applicable...intelligence information could be distributed concurrently (" smart push"). Intelligence officers sitting alongside the operational tasking officers would

On the transition from pulled to pushed monotonic fronts of the extended Fisher Kolmogorov equation

NASA Astrophysics Data System (ADS)

Benguria, R. D.; Depassier, M. C.

2005-10-01

The extended Fisher-Kolmogorov equation ut=uxx-γuxxxx+f(u) with arbitrary positive f(u), satisfying f(0)=f(1)=0, has monotonic traveling fronts for γ<{1}/{12}. We find a simple lower bound on the speed of the fronts which allows to determine, for a given reaction term, when will the front of minimal speed be pushed.

Push-pull strategy in the regulation of postembryonic root development.

PubMed

Choe, Goh; Lee, Ji-Young

2017-02-01

Unlike animals, plants continue to grow throughout their lives. The stem cell niche, protected in meristems of shoots and roots, enables this process. In the root, stem cells produce precursors for highly organized cell types via asymmetric cell divisions. These precursors, which are "transit-amplifying cells," actively divide for several rounds before entering into differentiation programs. In this review, we highlight positive feedback regulation between shoot- and root-ward signals during the postembryonic root growth, which is reminiscent of a "push-pull strategy" in business parlance. This property of molecular networks underlies the regulation of stem cells and their organizer, the "quiescent center," as well as of the signaling between stem cell niche, transit-amplifying cells, and beyond. Copyright © 2016 Elsevier Ltd. All rights reserved.

Friction Pull Plug Welding in Aluminum Alloys

NASA Technical Reports Server (NTRS)

Brooke, Shane A.; Bradford, Vann; Burkholder, Jonathon

2011-01-01

NASA fs Marshall Space Flight Center (MSFC) has recently invested much time and effort into the process development of Friction Pull Plug Welding (FPPW). FPPW, is a welding process similar to Friction Push Plug Welding in that, there is a small rotating part (plug) being spun and simultaneously pulled (forged) into a larger part. These two processes differ, in that push plug welding requires an internal reaction support, while pull plug welding reacts to the load externally. FPPW was originally conceived as a post proof repair technique for External Tank. FPPW was easily selected as the primary process used to close out the termination hole on the Constellation Program fs ARES I Upper Stage circumferential Self ] Reacting Friction Stir Welds (SR ]FSW). The versatility of FPPW allows it to also be used as a repair technique for both SR ]FSW and Conventional Friction Stir Welds. To date, all MSFC led development has been concentrated on aluminum alloys (2195, 2219, and 2014). Much work has been done to fully understand and characterize the process fs limitations. A heavy emphasis has been spent on plug design, to match the various weldland thicknesses and alloy combinations. This presentation will summarize these development efforts including weld parameter development, process control, parameter sensitivity studies, plug repair techniques, material properties including tensile, fracture and failure analysis.

Friction Pull Plug Welding in Aluminum Alloys

NASA Technical Reports Server (NTRS)

Brooke, Shane A.; Bradford, Vann

2012-01-01

NASA's Marshall Space Flight Center (MSFC) has recently invested much time and effort into the process development of Friction Pull Plug Welding (FPPW). FPPW, is a welding process similar to Friction Push Plug Welding in that, there is a small rotating part (plug) being spun and simultaneously pulled (forged) into a larger part. These two processes differ, in that push plug welding requires an internal reaction support, while pull plug welding reacts to the load externally. FPPW was originally conceived as a post proof repair technique for the Space Shuttle fs External Tank. FPPW was easily selected as the primary weld process used to close out the termination hole on the Constellation Program's ARES I Upper Stage circumferential Self-Reacting Friction Stir Welds (SR-FSW). The versatility of FPPW allows it to also be used as a repair technique for both SR-FSW and Conventional Friction Stir Welds. To date, all MSFC led development has been concentrated on aluminum alloys (2195, 2219, and 2014). Much work has been done to fully understand and characterize the process's limitations. A heavy emphasis has been spent on plug design, to match the various weldland thicknesses and alloy combinations. This presentation will summarize these development efforts including weld parameter development, process control, parameter sensitivity studies, plug repair techniques, material properties including tensile, fracture and failure analysis.

CAN UPPER EXTREMITY FUNCTIONAL TESTS PREDICT THE SOFTBALL THROW FOR DISTANCE: A PREDICTIVE VALIDITY INVESTIGATION

PubMed Central

Hanney, William J.; Kolber, Morey J.; Davies, George J.; Riemann, Bryan

2011-01-01

Introduction: Understanding the relationships between performance tests and sport activity is important to the rehabilitation specialist. The purpose of this study was two- fold: 1) To identify if relationships exist between tests of upper body strength and power (Single Arm Seated Shot Put, Timed Push-Up, Timed Modified Pull-Up, and The Davies Closed Kinetic Chain Upper Extremity Stability Test, and the softball throw for distance), 2) To determine which variable or group of variables best predicts the performance of a sport specific task (the softball throw for distance). Methods: One hundred eighty subjects (111 females and 69 males, aged 18-45 years) performed the 5 upper extremity tests. The Pearson product moment correlation and a stepwise regression were used to determine whether relationships existed between performance on the tests and which upper extremity test result best explained the performance on the softball throw for distance. Results: There were significant correlations (r=.33 to r=.70, p=0.001) between performance on all of the tests. The modified pull-up test was the best predictor of the performance on the softball throw for distance (r2= 48.7), explaining 48.7% of variation in performance. When weight, height, and age were added to the regression equation the r2 values increased to 64.5, 66.2, and 67.5 respectively. Conclusion: The results of this study indicate that several upper extremity tests demonstrate significant relationships with one another and with the softball throw for distance. The modified pull up test was the best predictor of performance on the softball throw for distance. PMID:21712942

O2-Promoted Allylic Acetoxylation of Alkenes: Assessment of "Push" vs. "Pull" Mechanisms and Comparison between O2 and Benzoquinone.

PubMed

Diao, Tianning; Stahl, Shannon S

2014-12-14

Palladium-catalyzed acetoxylation of allylic C-H bonds has been the subject of extensive study. These reactions proceed via allyl-palladium(II) intermediates that react with acetate to afford the allyl acetate product. Benzoquinone and molecular oxygen are two common oxidants for these reactions. Benzoquinone has been shown to promote allyl acetate formation from well-defined π-allyl palladium(II) complexes. Here, we assess the ability of O 2 to promote similar reactions with a series of "unligated" π-allyl palladium(II) complexes (i.e., in the absence of ancillary phosphorus, nitrogen or related donor ligands). Stoichiometric and catalytic allyl acetate formation is observed under aerobic conditions with several different alkenes. Mechanistic studies are most consistent with a "pull" mechanism in which O 2 traps the Pd 0 intermediate following reversible C-O bond-formation from an allyl-palladium(II) species. A "push" mechanism, involving oxidatively induced C-O bond formation, does not appear to participate. These results and conclusions are compared with benzoquinone-promoted allylic acetoxylation, in which a "push" mechanism seems to be operative.

Multilevel samplers as microcosms to assess microbial response to biostimulation

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

Baldwin, Brett R.; Peacock, Aaron D.; Park, Melora M.

Passive multilevel samplers (MLS) containing a solid matrix for microbial colonization were used in conjunction with a push-pull biostimulation experiment designed to promote biological U(VI) and Tc(VII) reduction. MLS were deployed at 24 elevations in the injection well and two down gradient wells to investigate the spatial variability in microbial community composition and growth prior to and following biostimulation. The microbial community was characterized by real-time PCR (Q-PCR) quantification of Bacteria, NO3- reducing bacteria (nirS and nirK), δ-proteobacteria, Geobacter sp., and methanogens (mcrA). Pretest cell densities were low overall but varied substantially with significantly greater Bacterial populations detected at circumneutralmore » pH (T-test, α=0.05) suggesting carbon substrate and low pH limitations of microbial activity. Although pretest cell densities were low, denitrifying bacteria were dominant members of the microbial community. Biostimulation with an ethanol amended groundwater resulted in concurrent NO3- and Tc(VII) reduction followed by U(VI) reduction. Q-PCR analysis of MLS revealed significant (1-2 orders of magnitude, T-test, α=0.05) increases in cell densities of Bacteria, denitrifiers, δ-proteobacteria, Geobacter sp., and methanogens in response to biostimulation. Traditionally characterization of sediment samples has been used to investigate the microbial community response to biostimulation, however, collection of sediment samples is expensive and not conducive to deep aquifers or temporal studies. The results presented demonstrate that push-pull tests with passive MLS provide an inexpensive approach to determine the effect of biostimulation on contaminant concentrations, geochemical conditions, and the microbial community composition and function.« less

14 CFR 25.693 - Joints.

Code of Federal Regulations, 2013 CFR

2013-01-01

... system joints (in push-pull systems) that are subject to angular motion, except those in ball and roller... in cable control systems. For ball or roller bearings, the approved ratings may not be exceeded...

Effectiveness of alternative rail passenger equipment crashworthiness strategies

DOT National Transportation Integrated Search

2006-04-04

Crashworthiness strategies, which include crash energy : management (CEM), pushback couplers, and push/pull : operation, are evaluated and compared under specific collision : conditions. Comparisons of three strategies are evaluated in : this paper: ...

Use of gas push-pull tests for the measurement of methane oxidation in different landfill cover soils.

PubMed

Streese-Kleeberg, Jan; Rachor, Ingke; Gebert, Julia; Stegmann, Rainer

2011-05-01

In order to optimise methane oxidation in landfill cover soils, it is important to be able to accurately quantify the amount of methane oxidised. This research considers the gas push-pull test (GPPT) as a possible method to quantify oxidation rates in situ. During a GPPT, a gas mixture consisting of one or more reactive gases (e.g., CH(4), O(2)) and one or more conservative tracers (e.g., argon), is injected into the soil. Following this, the mixture of injected gas and soil air is extracted from the same location and periodically sampled. The kinetic parameters for the biological oxidation taking place in the soil can be derived from the differences in the breakthrough curves. The original method of Urmann et al. (2005) was optimised for application in landfill cover soils and modified to reduce the analytical effort required. Optimised parameters included the flow rate during the injection phase and the duration of the experiment. 50 GPPTs have been conducted at different landfills in Germany during different seasons. Generally, methane oxidation rates ranged between 0 and 150 g m(soil air)(-3)h(-1). At one location, rates up to 440 g m(soil air)(-3)h(-1) were measured under particularly favourable conditions. The method is simple in operation and does not require expensive equipment besides standard laboratory gas chromatographs. Copyright © 2010 Elsevier Ltd. All rights reserved.

Pull or Push? Octopuses Solve a Puzzle Problem

PubMed Central

Richter, Jonas N.; Hochner, Binyamin; Kuba, Michael J.

2016-01-01

Octopuses have large brains and exhibit complex behaviors, but relatively little is known about their cognitive abilities. Here we present data from a five-level learning and problem-solving experiment. Seven octopuses (Octopus vulgaris) were first trained to open an L shaped container to retrieve food (level 0). After learning the initial task all animals followed the same experimental protocol, first they had to retrieve this L shaped container, presented at the same orientation, through a tight fitting hole in a clear Perspex partition (level 1). This required the octopuses to perform both pull and release or push actions. After reaching criterion the animals advanced to the next stage of the test, which would be a different consistent orientation of the object (level 2) at the start of the trial, an opaque barrier (level 3) or a random orientation of the object (level 4). All octopuses were successful in reaching criterion in all levels of the task. At the onset of each new level the performance of the animals dropped, shown as an increase in working times. However, they adapted quickly so that overall working times were not significantly different between levels. Our findings indicate that octopuses show behavioral flexibility by quickly adapting to a change in a task. This can be compared to tests in other species where subjects had to conduct actions comprised of a set of motor actions that cannot be understood by a simple learning rule alone. PMID:27003439

Push-pull converter with energy saving circuit for protecting switching transistors from peak power stress

NASA Technical Reports Server (NTRS)

Mclyman, W. T. (Inventor)

1981-01-01

In a push-pull converter, switching transistors are protected from peak power stresses by a separate snubber circuit in parallel with each comprising a capacitor and an inductor in series, and a diode in parallel with the inductor. The diode is connected to conduct current of the same polarity as the base-emitter juction of the transistor so that energy stored in the capacitor while the transistor is switched off, to protect it against peak power stress, discharges through the inductor when the transistor is turned on, and after the capacitor is discharges through the diode. To return this energy to the power supply, or to utilize this energy in some external circuit, the inductor may be replaced by a transformer having its secondary winding connected to the power supply or to the external circuit.

Establishing a relationship between maximum torque production of isolated joints to simulate EVA ratchet push-pull maneuver: A case study

NASA Technical Reports Server (NTRS)

Pandya, Abhilash; Maida, James; Hasson, Scott; Greenisen, Michael; Woolford, Barbara

1993-01-01

As manned exploration of space continues, analytical evaluation of human strength characteristics is critical. These extraterrestrial environments will spawn issues of human performance which will impact the designs of tools, work spaces, and space vehicles. Computer modeling is an effective method of correlating human biomechanical and anthropometric data with models of space structures and human work spaces. The aim of this study is to provide biomechanical data from isolated joints to be utilized in a computer modeling system for calculating torque resulting from any upper extremity motions: in this study, the ratchet wrench push-pull operation (a typical extravehicular activity task). Established here are mathematical relationships used to calculate maximum torque production of isolated upper extremity joints. These relationships are a function of joint angle and joint velocity.

Microwave Assisted Synthesis, Physicochemical, Photophysical, Single Crystal X-ray and DFT Studies of Novel Push-Pull Chromophores.

PubMed

Khan, Salman A; Asiri, Abdullah M; Basisi, Hadi Mussa; Arshad, Muhammad Nadeem; Sharma, Kamlesh

2015-11-01

Two push-pull chromophores were synthesized by knoevenagel condensation under microwave irradiation. The structure of synthesized chromophores were established by spectroscopic (FT-IR, (1)H NMR, (13)C NMR, EI-MS) and elemental analysis. Structure of the chromophores was further conformed by X-ray crystallographic. UV-Vis and fluorescence spectroscopy measurements provided that chromophores were good absorbent and fluorescent properties. Fluorescence polarity studies demonstrated that chromophores were sensitive to the polarity of the microenvironment provided by different solvents. Physicochemical parameters, including singlet absorption, extinction coefficient, stokes shift, oscillator strength, dipole moment and flurescence quantum yield were investigated in order to explore the analytical potential of the synthesized chromophores. In addition, the total energy, frontier molecular orbitals, hardness, electron affinity, ionization energy, electrostatic potential map were also studied computationally by using density functional theoretical method.

Push-pull radio frequency circuit with integral transistion to waveguide output

DOEpatents

Bennett, Wilfred P.

1987-01-01

A radio frequency circuit for ICRF heating includes a resonant push-pull circuit, a double ridged rectangular waveguide, and a coupling transition which joins the waveguide to the resonant circuit. The resonant circuit includes two cylindrical conductors mounted side by side and two power vacuum tubes attached to respective ends of a cylindrical conductor. A conductive yoke is located at the other end of the cylindrical conductors to short circuit the two cylindrical conductors. The coupling transition includes two relatively flat rectangular conductors extending perpendicular to the longitudinal axes of a respective cylindrical conductor to which the flat conductor is attached intermediate the ends thereof. Conductive side covers and end covers are also provided for forming pockets in the waveguide into which the flat conductors extend when the waveguide is attached to a shielding enclosure surrounding the resonant circuit.

The push and pull of grief: Approach and avoidance in bereavement.

PubMed

Maccallum, Fiona; Sawday, Simon; Rinck, Mike; Bryant, Richard A

2015-09-01

Prolonged Grief (PG) is recognized as a post-bereavement syndrome that is associated with significant impairment. Although approach and avoidance tendencies have both been hypothesized to play key roles in maintaining PG symptoms, understanding of these relationships has been limited by a reliance on self-report methodology. This study applies an experimental paradigm to simultaneously investigate the relationship between PG severity and approach-avoidance behavioral tendencies. Fifty-five bereaved individuals with and without PG completed a behavioral measure of approach and avoidance responding in which they pulled or pushed a joystick in response to grief-related, positive, negative and neutral images that appeared on a computer screen. Concurrent visual feedback created the illusion that the images were either approaching or receding from the participant. Half of the participants also received a prime designed to activate their grief prior to the task. Irrespective of prime condition, PG participants pulled grief-related images more quickly than they pushed them. This difference was not observed in response to non-grief related images. Non PG participants showed no difference in their reaction times to grief-stimuli. This study was undertaken in a nonclinical setting and the majority of participants had lost a loved one due to chronic illness. Future research with treatment-seeking populations and sudden loss will be needed to explore the generalizability of the findings. The findings from this study provide preliminary evidence supporting models of PG that integrate approach and avoidance tendencies. Copyright © 2015 Elsevier Ltd. All rights reserved.

Physicians' Migration: Perceptions of Pakistani Medical Students.

PubMed

Hossain, Nazli; Shah, Nusrat; Shah, Tahira; Lateef, Sidra Binte

2016-08-01

To study the perceptions of medical students about factors responsible for physicians'migration. Cross-sectional survey. Dow Medical College and Civil Hospital, Karachi, from April to May 2015. Aself-administered structured questionnaire was used including demographic details, attitudes about push and pull factors of migration, and reasons for migrating or not migrating abroad. Final year students and interns were included. Likert scale from 1 to 4 (1=strongly disagree to 4=strongly agree) was used to assess attitudes. Data was analyzed by SPSS version 16. Atotal of 240 medical students, mostly females (n=181, 75%) (60% final year and 40% interns), participated in the study. Majority wished to go abroad (n=127; 54%) with United States being the favourite destination (n=80; 66.1%) and internal medicine fields being the preferred choice for specialization (n=126; 54%). The major pull factors were better quality of postgraduate education abroad (n=110; 48.2%) and economic prospects (80; 35.2%); while the push factors were a weak healthcare system (n=219; 94.3%), inadequate salary structure (n=205; 88.3%), insecurity (n=219; 93.9%) and increasing religious intolerance in Pakistan (n=183; 78.5%). This survey highlights the continuing trend of physician migration from Pakistan owing to an interplay of various push and pull factors. Majority of our medical students wish to migrate, mainly due to low salaries, poor job structure, and insecurity. Urgent interventions are required to reverse this trend of medical brain-drain.

Ethics, effectiveness and population health information interventions: a Canadian analysis.

PubMed

Greyson, Devon; Knight, Rod; Shoveller, Jean A

2018-02-19

Population health information interventions (PHIIs) use information in efforts to promote health. PHIIs may push information to a target audience (communication), pull information from the public (surveillance), or combine both in a bidirectional intervention. Although PHIIs have often been framed as non-invasive and ethically innocuous, in reality they may be intrusive into people's lives, affecting not only their health but their senses of security, respect, and self-determination. Ethical acceptability of PHIIs may have impacts on intervention effectiveness, potentially giving rise to unintended consequences. This article examines push, pull, and bidirectional PHIIs using empirical data from an ethnographic study of young mothers in Greater Vancouver, Canada. Data were collected from October 2013 to December 2014 via naturalistic observation and individual interviews with 37 young mothers ages 16-22. Transcribed interviews and field notes were analyzed using inductive qualitative thematic analysis. Both push and pull interventions were experienced as non-neutral by the target population, and implementation factors on a structural and individual scale affected intervention ethics and effectiveness. Based on our findings, we suggest that careful ethical consideration be applied to use of PHIIs as health promotion tools. Advancing the 'ethics of PHIIs' will benefit from empirical data that is informed by information and computer science theory and methods. Information technologies, digital health promotion services, and integrated surveillance programs reflect important areas for investigation in terms of their effects and ethics. Health promotion researchers, practitioners, and ethicists should explore these across contexts and populations.

An on-line push/pull perfusion-based hollow-fiber liquid-phase microextraction system for high-performance liquid chromatographic determination of alkylphenols in water samples.

PubMed

Chao, Yu-Ying; Jian, Zhi-Xuan; Tu, Yi-Ming; Wang, Hsaio-Wen; Huang, Yeou-Lih

2013-06-07

In this study, we employed a novel on-line method, push/pull perfusion hollow-fiber liquid-phase microextraction (PPP-HF-LPME), to extract 4-tert-butylphenol, 2,4-di-tert-butylphenol, 4-n-nonylphenol, and 4-n-octylphenol from river and tap water samples; we then separated and quantified the extracted analytes through high-performance liquid chromatography (HPLC). Using this approach, we overcame the problem of fluid loss across the porous HF membrane to the donor phase, permitting on-line coupling of HF-LPME to HPLC. In our PPP-HF-LPME system, we used a push/pull syringe pump as the driving source to perfuse the acceptor phase, while employing a heating mantle and an ultrasonic probe to accelerate mass transfer. We optimized the experimental conditions such as the nature of the HF supported intermediary phase and the acceptor phase, the composition of the donor and acceptor phases, the sample temperature, and the sonication conditions. Our proposed method provided relative standard deviations of 3.1-6.2%, coefficients of determination (r(2)) of 0.9989-0.9998, and limits of detection of 0.03-0.2 ng mL(-1) for the analytes under the optimized conditions. When we applied this method to analyses of river and tap water samples, our results confirmed that this microextraction technique allows reliable monitoring of alkylphenols in water samples.

Comparison between a classical command law and a new advanced recovery command law in a MCB-ARS boost

NASA Astrophysics Data System (ADS)

Petit, Pierre; Saint-Eve, Frédéric; Sawicki, Jean-Paul; Aillerie, Michel

2017-02-01

This paper focuses on an original performed command on DC-DC boosts developed for applications in the LMOPS lab for the photovoltaic energy conversion and more specifically the Photovoltaic panels connected to HVDC smart grids. This boost, commonly named MCB-ARS (Magnetically Coupled Boost with Active Recovery Switch) presents great advantages concerning the simplicity of the command on the single constitutive switch, the global efficiency and the voltage conversion ratio. A fine analysis of the losses all over the entire converter shows that losses are not distributed uniformly in the constituting components. So a previous modification described in a previous paper consisting in the conducting assistance on the power flowing intermediate diode, performed advantageously the global efficiency. The present analysis takes into account the fact that the new configuration obtained after this important improvement looks like a classical half-bridge push-pull stage and may be controlled by a twice complementary command. In that way, a comparison has been done between a natural commutation recovery diode and an assisted switch commutation driven in a push-pull mode. As attempted, the switching command laws in charge to assume the energy transfer has been compared to the classical previous system described in anterior papers, and we demonstrate in this publication that a commutation based on a push-pull command mode within the two switches of the MCB-ARS converter is possible and increases the power transfer.

Dual-Force Vaginoplasty for Treatment of Segmental Vaginal Aplasia.

PubMed

El Saman, Ali M; Farag, Mohamad A; Shazly, Sherif A; Noor, Mohamed; Ali, Mohammed K; Othman, Essam R; Khalifa, Mansour; Farghly, Tarek A; El Saman, Dina A

2017-05-01

Vaginal aplasia occurs in 1 in 5,000-10,000 female live births. In this report, we evaluated a novel dual-force vaginoplasty technique for treatment of 11 patients with segmental vaginal aplasia. The principle of the approach is to thin the atretic part between two counteracting forces. The instrument was inserted laparoscopically into the proximal hematocolpos. Two balloon catheters, one for drainage and one for traction, were threaded over the inserter. The traction catheter was then threaded over a silicon tube, leaving the balloon in the proximal portion of the vagina and connecting across the vaginal septum to a fenestrated Teflon olive, which was positioned against the distal surface of the vaginal septum. This created a dual "pushing and pulling" force across the septum, which, over 3-4 days, pulls the upper vaginal pouch down while the vaginal dimple is pushed up. The aplastic segment becomes thin and easy to dilate and permits achievement of vaginal patency. The drainage of the hematocolpos is predominantly through the balloon catheter so postoperative wound management is facilitated. Eleven menarchal girls were diagnosed with segmental vaginal aplasia. The dual-force vaginoplasty was performed on each and was tolerated well with no operative complications. They all reported establishment of the menstrual cycle and significant improvement of pain during follow-up. Creation of a dual pushing-pulling force on the atretic vaginal segment is a feasible short procedure for management of segmental vaginal aplasia.

14 CFR 23.693 - Joints.

Code of Federal Regulations, 2013 CFR

2013-01-01

... Systems § 23.693 Joints. Control system joints (in push-pull systems) that are subject to angular motion... factor may be reduced to 2.0 for joints in cable control systems. For ball or roller bearings, the...

Designing a warm-up protocol for elite bob-skeleton athletes.

PubMed

Cook, Christian; Holdcroft, Danny; Drawer, Scott; Kilduff, Liam P

2013-03-01

To investigate how different warm-ups influenced subsequent sled-pull sprint performance in Olympic-level bob-skeleton athletes as part of their preparation for the 2010 Winter Olympics. Three female and 3 male athletes performed 5 different randomized warm-ups of differing intensities, durations, and timing relative to subsequent testing, each 2 days apart, all repeated twice. After warm-ups, testing on a sled-pull sprint over 20 m, 3 repeats 3 min apart, took place. Performance testing showed improvement (P < .001, ES > 1.2) with both increasing intensity of warm-up and closeness of completion to testing, with 20-m sled sprinting being 0.1-0.25 s faster in higher-intensity protocols performed near testing In addition, supplementing the warm-ups by wearing of a light survival coat resulted in further performance improvement (P = .000, ES 1.8). Changing timing and intensity of warm-up and using an ancillary passive heat-retention device improved sprint performance in Olympic-level bob-skeleton athletes. Subsequent adoption of these on the competitive circuit was associated with a seasonal improvement in push times and was ultimately implemented in the 2010 Winter Olympics.

Low-Back Biomechanics and Static Stability During Isometric Pushing

PubMed Central

Granata, Kevin P.; Bennett, Bradford C.

2006-01-01

Pushing and pulling tasks are increasingly prevalent in industrial workplaces. Few studies have investigated low-back biomechanical risk factors associated with pushing, and we are aware of none that has quantified spinal stability during pushing exertions. Data recorded from 11 healthy participants performing isometric pushing exertions demonstrated that trunk posture, vector force direction of the applied load, and trunk moment were influenced (p < .01) by exertion level, elevation of the handle for the pushing task, and foot position. A biomechanical model was used to analyze the posture and hand force data gathered from the pushing exertions. Model results indicate that pushing exertions provide significantly (p < .01) less stability than lifting when antagonistic cocontraction is ignored. However, stability can be augmented by recruitment of muscle cocontraction. Results suggest that cocontraction may be recruited to compensate for the fact that equilibrium mechanics provide little intrinsic trunk stiffness and stability during pushing exertions. If one maintains stability by means of cocontraction, additional spinal load is thereby created, increasing the risk of overload injury. Thus it is important to consider muscle cocontraction when evaluating the biomechanics of pushing exertions. Potential applications of this research include improved assessment of biomechanical risk factors for the design of industrial pushing tasks. PMID:16435695

Demonstration of In situ Anaerobic Transformation of Toluene and Xylene Using Single-Well Push-Pull Tests and Deuterated BTEX Surrogates

NASA Astrophysics Data System (ADS)

Field, J. A.; Reusser, D. E.; Beller, H. R.; Istok, J. D.

2001-12-01

Obtaining unambiguous evidence of in-situ transformation of benzene, toluene, ethylbenzene and xylene (BTEX) in the subsurface is a difficult task. Recently, benzylsuccinic acid and its methyl analogues were shown to be unequivocal degradation products of anaerobic toluene and xylene biodegradation. Conducting tracer tests at BTEX-contaminated field sites is problematic because background contaminant concentrations potentially interfere with the interpretation of field test data. To avoid the time and cost associated with removing background contaminants, alternative approaches are needed. Deuterated analogs of toluene and xylene are well-suited for use in field tracer tests because they are inexpensive and can be distinguished analytically from background toluene and xylene. In this study, single-well push-pull tests, in which deuterated toluene and xylene were injected, were performed to assess the in-situ anaerobic biotransformation of toluene and xylene in BTEX-contaminated wells. A total of 4 single-well push-pull tests were conducted at BTEX-contaminated field sites near Portland, OR and Kansas City, KS. Test solutions consisting of 100 mg/L bromide, 250 mg/L nitrate, 0.4 to 2.5 mg/L toluene-d8, and 0.4 to 1.0 mg/L o-xylene-d10.were injected at a rate of 0.5 - 2 L/min. During the extraction phase, samples were taken daily to biweekly for up to 30 days. Samples for volatile organic analytes were collected in 40-mL volatile organic analysis (VOA) vials without headspace. Samples for BSA and methyl-BSA were collected in 1 L glass bottles and preserved with 5% (w/w) formalin. Samples were shipped on ice and stored at 4 C until analysis. Unambiguous evidence of toluene and xylene biotransformation was obtained with the in-situ formation of BSA and methyl-BSA. The concentrations of BSA ranged from below the detection limit (0.2 ug/L) to 1.5 ug/L. The concentrations of methyl-BSA ranged from below detection to the quantitation limit (0.7 ug/L). The highest BSA concentrations detected corresponded to 0.1 - 0.2 mol% of the injected deuterated toluene. Zero-order degradation rates for deuterated toluene, estimated as the rates of BSA formation, were 0.0004 to 0.001 day-1. Because methyl-BSA concentrations did not exceed the quantitation limit, the rate of xylene degradation could not be calculated. The formation of BSA and methyl-BSA was coupled with the utilization of nitrate, presumably due to denitrification. Transformation of toluene and xylene to BSA and methyl-BSA, respectively, was observed for wells characterized by low concentrations of toluene and xylene relative to total BTEX. To the best of our knowledge, this is the first report to document the use of deuterated BTEX surrogates in field-tracer experiments.

A brief description of the biomechanics and physiology of a strongman event: the tire flip.

PubMed

Keogh, Justin W L; Payne, Amenda L; Anderson, Brad B; Atkins, Paul J

2010-05-01

The purpose of this study was to (a) characterize the temporal aspects of a popular strongman event, the tire flip; (b) gain some insight into the temporal factors that could distinguish the slowest and fastest flips; and (c) obtain preliminary data on the physiological stress of this exercise. Five resistance-trained subjects with experience in performing the tire flip gave informed consent to participate in this study. Each subject performed 2 sets of 6 tire flips with a 232-kg tire with 3 minutes of rest between sets. Temporal variables were obtained from video cameras positioned 10 m from the tire, perpendicular to the intended direction of the tire flip. Using the "stopwatch" function in Silicon Coach, the duration of each tire flip and that of the first pull, second pull, transition, and push phases were recorded. Physiological stress was estimated via heart rate and finger-prick blood lactate response. Independent T-tests revealed that the 2 faster subjects (0.38 +/- 0.17 s) had significantly (p < 0.001) shorter second pull durations than the 3 slower subjects (1.49 +/- 0.92 s). Paired T-tests revealed that the duration of the second pull for each subject's fastest 3 trials (0.55 +/- 0.35 s) were significantly (p = 0.007) less than their 3 slowest trials (1.69 +/- 1.35 s). Relatively high heart rate (179 +/- 8 bpm) and blood lactate (10.4 +/- 1.3 mmol/L(-1)) values were found at the conclusion of the second set. Overall, the results of this study suggest that the duration of the second pull is a key determinant of tire flip performance and that this exercise provides relatively high degrees of physiological stress.

Fatigue of DIN 1.4914 martensitic stainless steel in a hydrogen environment

NASA Astrophysics Data System (ADS)

Shakib, J. I.; Ullmaier, H.; Little, E. A.; Faulkner, R. G.; Schmilz, W.; Chung, T. E.

1994-09-01

Fatigue tests at room temperature in vacuum, air and hydrogen have been carried out on specimens of DIN 1.4914 martensitic stainless steel in load-controlled, push-pull type experiments. Fatigue lifetimes in hydrogen are significantly lower than in both vacuum and air and the degradation is enhanced by lowering the test frequency or introducing hold times into the tension half-cycle. Fractographic examinations reveal hydrogen embrittlement effects in the form of internal cracking between fatigue striations together with surface modifications, particularly at low stress amplitudes. It is suggested that gaseous hydrogen can influence both fatigue crack initiation and propagation events in martensitic steels.

Flight test results for several light, canard-configured airplanes

NASA Technical Reports Server (NTRS)

Brown, Philip W.

1987-01-01

Brief flight evaluations of two different, light, composite constructed, canard and winglet configured airplanes were performed to assess their handling qualities; one airplane was a single engine, pusher design and the other a twin engine, push-pull configuration. An emphasis was placed on the slow speed/high angle of attack region for both airplanes and on the engine-out regime for the twin. Mission suitability assessment included cockpit and control layout, ground and airborne handling qualities, and turbulence response. Very limited performance data was taken. Stall/spin tests and the effects of laminar flow loss on performance and handling qualities were assessed on an extended range, single engine pusher design.

Designing for diffusion: how can we increase uptake of cancer communication innovations?

PubMed

Dearing, James W; Kreuter, Matthew W

2010-12-01

The best innovations in cancer communication do not necessarily achieve uptake by researchers, public health and clinical practitioners, and policy makers. This paper describes design activities that can be applied and combined for the purpose of spreading effective cancer communication innovations. A previously developed Push-Pull-Infrastructure Model is used to organize and highlight the types of activities that can be deployed during the design phase of innovations. Scientific literature about the diffusion of innovations, knowledge utilization, marketing, public health, and our experiences in working to spread effective practices, programs, and policies are used for this purpose. Attempts to broaden the reach, quicken the uptake, and facilitate the use of cancer communication innovations can apply design activities to increase the likelihood of diffusion. Some simple design activities hold considerable promise for improving dissemination and subsequent diffusion. Augmenting current dissemination practices with evidence-based concepts from diffusion science, marketing science, and knowledge utilization hold promise for improving results by eliciting greater market pull. Inventors and change agencies seeking to spread cancer communication innovations can experience more success by explicit consideration of design activities that reflect an expanded version of the Push-Pull-Infrastructure Model. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

Designing for Diffusion: How Can We Increase Uptake of Cancer Communication Innovations?

PubMed Central

Dearing, James W.; Kreuter, Matthew W.

2010-01-01

Objective The best innovations in cancer communication do not necessarily achieve uptake by researchers, public health and clinical practitioners, and policy makers. This paper describes design activities that can be applied and combined for the purpose of spreading effective cancer communication innovations. Methods A previously developed Push-Pull-Infrastructure Model is used to organize and highlight the types of activities that can be deployed during the design phase of innovations. Scientific literature about the diffusion of innovations, knowledge utilization, marketing, public health, and our experiences in working to spread effective practices, programs, and policies are used for this purpose. Results Attempts to broaden the reach, quicken the uptake, and facilitate the use of cancer communication innovations can apply design activities to increase the likelihood of diffusion. Some simple design activities hold considerable promise for improving dissemination and subsequent diffusion. Conclusion Augmenting current dissemination practices with evidence-based concepts from diffusion science, marketing science, and knowledge utilization hold promise for improving results by eliciting greater market pull. Practice Implications Inventors and change agencies seeking to spread cancer communication innovations can experience more success by explicit consideration of design activities that reflect an expanded version of the Push-Pull-Infrastructure Model. PMID:21067884

Discontinuous Mode Power Supply

NASA Technical Reports Server (NTRS)

Lagadinos, John; Poulos, Ethel

2012-01-01

A document discusses the changes made to a standard push-pull inverter circuit to avoid saturation effects in the main inverter power supply. Typically, in a standard push-pull arrangement, the unsymmetrical primary excitation causes variations in the volt second integral of each half of the excitation cycle that could lead to the establishment of DC flux density in the magnetic core, which could eventually cause saturation of the main inverter transformer. The relocation of the filter reactor normally placed across the output of the power supply solves this problem. The filter reactor was placed in series with the primary circuit of the main inverter transformer, and is presented as impedance against the sudden changes on the input current. The reactor averaged the input current in the primary circuit, avoiding saturation of the main inverter transformer. Since the implementation of the described change, the above problem has not reoccurred, and failures in the main power transistors have been avoided.

Technology push, market pull, and the Valley of Death

NASA Astrophysics Data System (ADS)

Swift, Gregory W.

2005-09-01

The Valley of Death is the gap between fundamental research and product development, where apparently promising technologies can stall or disappear. Fundamental researchers may hope for potential applications of their work, and they try to push technology based on their research. Businesses may hope that new technology might serve their market needs, and they try to find promising new technologies that can be pulled toward practical use. The valley between the researchers and the businesses can be surprisingly twisted and thorny, despite government attempts to build roads across it. The histories of cryogenic engineering in the late 20th century and of thermoacoustics work at Los Alamos offer examples of both useful and misguided strategies in this valley. Although global thermoacoustics R&D has not (yet?) been as successful as cryogenic engineering, thermoacoustics has thus far avoided some of the worst pitfalls in the valley.

The [2+2] Cycloaddition-Retroelectrocyclization (CA-RE) Click Reaction: Facile Access to Molecular and Polymeric Push-Pull Chromophores.

PubMed

Michinobu, Tsuyoshi; Diederich, François

2018-03-26

The [2+2] cycloaddition-retroelectrocyclization (CA-RE) reaction between electron-rich alkynes and electron-deficient alkenes is an efficient procedure to create nonplanar donor-acceptor (D-A) chromophores in both molecular and polymeric platforms. They feature attractive properties including intramolecular charge-transfer (ICT) bands, nonlinear optical properties, and redox activities for use in next-generation electronic and optoelectronic devices. This Review summarizes the development of the CA-RE reaction, starting from the initial reports with organometallic compounds to the extension to purely organic systems. The structural requirements for rapid, high-yielding transformations with true click chemistry character are illustrated by examples that include the broad alkyne and alkene substitution modes. The CA-RE click reaction has been successfully applied to polymer synthesis, with the resulting polymeric push-pull chromophores finding many interesting applications. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Simultaneously 'pushing' and 'pulling' graphene oxide into low-polar solvents through a designed interface.

PubMed

Liu, Zhen; Liu, Jingquan; Wang, Yichao; Razal, Joselito M; Francis, Paul S; Biggs, Mark J; Barrow, Colin J; Yang, Wenrong

2018-08-03

Dispersing graphene oxide (GO) in low-polar solvents can realize a perfect self-assembly with functional molecules and application in removal of organic impurities that only dissolve in low-polar solvents. The surface chemistry of GO plays an important role in its dispersity in these solvents. The direct transfer of hydrophilic GO into low-polar solvents, however, has remained an experimental challenge. In this study, we design an interface to transfer GO by simultaneously 'pushing and pulling' the nanosheets into low-polar solvents. Our approach is outstanding due to the ability to obtain monolayers of chemically reduced GO (CRGO) with designed surface properties in the organic phase. Using the transferred GO or CRGO dispersions, we have fabricated GO/fullerene nanocomposites and assessed the ability of CRGOs for dye adsorption. We hope our work can provide a universal approach for the phase transfer of other nanomaterials.

Power spectral density analysis of the electromyogram from a work task performed in a full pressure suit. Ph.D. Thesis - Houston Univ.; [for determining muscular fatigue

NASA Technical Reports Server (NTRS)

Lafevers, E. V.

1974-01-01

Surface electromyograms (EMG) taken from three upper torso muscles during a push-pull task were analyzed by a power spectral density technique to determine the utility of the spectral analysis for identifying changes in the EMG caused by muscular fatigue. The results confirmed the value of the frequency analysis for identifying fatigue producing muscular performance. Data revealed reliable differences between muscles in fatigue induced responses to various locations in the reach envelope at which the subjects were required to perform the push-pull exercise, and the differential sensitivity of individual muscles to the various reach positions; i.e., certain reach positions imposed more fatigue related shifts in EMG power than did others. It was found that a pressurized space suit changed the pattern of normal shirtsleeve muscle fatigue responses in all three of the muscles.

A Push-pull Protocol to Reduce Colonization of Bird Nest Boxes by Honey Bees.

PubMed

Efstathion, Caroline A; Kern, William H

2016-09-04

Introduction of the invasive Africanized honey bee (AHB) into the Neotropics is a serious problem for many cavity nesting birds, specifically parrots. These bees select cavities that are suitable nest sites for birds, resulting in competition. The difficulty of removing bees and their defensive behavior makes a prevention protocol necessary. Here, we describe a push-pull integrated pest management protocol to deter bees from inhabiting bird boxes by applying a bird safe insecticide, permethrin, to repel bees from nest boxes, while simultaneously attracting them to pheromone-baited swarm traps. Shown here is an example experiment using Barn Owl nest boxes. This protocol successfully reduced colonization of Barn Owl nest boxes by Africanized honey bees. This protocol is flexible, allowing adjustments to accommodate a wide range of bird species and habitats. This protocol could benefit conservation efforts where AHB are located.

Neutrally buoyant tracers in hydrogeophysics: Field demonstration in fractured rock

NASA Astrophysics Data System (ADS)

Shakas, Alexis; Linde, Niklas; Baron, Ludovic; Selker, John; Gerard, Marie-Françoise; Lavenant, Nicolas; Bour, Olivier; Le Borgne, Tanguy

2017-04-01

Electrical and electromagnetic methods are extensively used to map electrically conductive tracers within hydrogeologic systems. Often, the tracers used consist of dissolved salt in water, leading to a denser mixture than the ambient formation water. Density effects are often ignored and rarely modeled but can dramatically affect transport behavior and introduce dynamics that are unrepresentative of the response obtained with classical tracers (e.g., uranine). We introduce a neutrally buoyant tracer consisting of a mixture of salt, water, and ethanol and monitor its movement during push-pull experiments in a fractured rock aquifer using ground-penetrating radar. Our results indicate a largely reversible transport process and agree with uranine-based push-pull experiments at the site, which is in contrast to results obtained using dense saline tracers. We argue that a shift toward neutrally buoyant tracers in both porous and fractured media would advance hydrogeophysical research and enhance its utility in hydrogeology.

Space platform power system hardware testbed

NASA Technical Reports Server (NTRS)

Sable, D.; Patil, A.; Sizemore, T.; Deuty, S.; Noon, J.; Cho, B. H.; Lee, F. C.

1991-01-01

The scope of the work on the NASA Space Platform includes the design of a multi-module, multi-phase boost regulator, and a voltage-fed, push-pull autotransformer converter for the battery discharger. A buck converter was designed for the charge regulator. Also included is the associated mode control electronics for the charger and discharger, as well as continued development of a comprehensive modeling and simulation tool for the system. The design of the multi-module boost converter is discussed for use as a battery discharger. An alternative battery discharger design is discussed using a voltage-fed, push-pull autotransformer converter. The design of the charge regulator is explained using a simple buck converter. The design of the mode controller and effects of locating the bus filter capacitor bank 20 feet away from the power ORU are discussed. A brief discussion of some alternative topologies for battery charging and discharging is included. The power system modeling is described.

Plasma Push and Pull

NASA Image and Video Library

2015-07-08

Dark strands of plasma hovering above the sun's surface began to interact with each other in a form of tug of war over two and a half days on June 28-30, 2015. At times, strands of plasma extended a tenuous connection between one area and the other. Twice the small tower of plasma to the lower left shot a burst of energy over to the quivering filament higher up. We are seeing the push and pull of magnetic forces revealed in a 193 wavelength of extreme ultraviolet light, typically colorized in brown. Credit: NASA/SDO NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Self-control in action: implicit dispositions toward goals and away from temptations.

PubMed

Fishbach, Ayelet; Shah, James Y

2006-05-01

Five studies examined whether, in self-control dilemmas, individuals develop an implicit disposition to approach goals and avoid temptations, psychologically as well as physically. Using a method developed by A. K. Solarz (1960; see also K. L. Duckworth, J. A. Bargh, M. Garcia, & S. Chaiken, 2002), the authors assessed the time for pulling and pushing a lever in response to goal- and temptation-related stimuli (e.g., studying and partying). The results show that individuals offset the influence of tempting activities by automatically avoiding these stimuli (faster pushing responses) and by approaching stimuli related to an overarching goal (faster pulling responses). These implicit self-control dispositions varied as a function of the magnitude of the self-control conflict, itself defined by how strongly individuals were attracted to temptations and held the longer term goal. These dispositions were further shown to play a role in successful self-control. Copyright 2006 APA.

Fractured-rock hydrogeophysics with electrically conductive and neutrally buoyant tracers

NASA Astrophysics Data System (ADS)

Shakas, A.; Linde, N.; Baron, L.; Le Borgne, T.; Bour, O.; Lavenant, N.; Gerard, M. F.

2016-12-01

Artificial tracer tests help to characterize and understand the dynamics of groundwater systems. This remains a challenging task, especially when dealing with highly heterogeneous formations in which flow can be very localized and the interpretation of tracer breakthrough curves may be ambiguous. As a complement to tracer tests, ground-penetrating radar (GPR) and electrical resistivity tomography can map the space-time migration of electrically conductive tracers. In hydrogeophysics, the most common tracer is dissolved table salt in water. However, conventional salt tracers lead to density effects that are often ignored. Even less than 1% density variations can have a dramatic effect on transport behavior and affect tracer tests in complex ways. Such effects have been demonstrated in our previous experiments that used single-hole GPR to monitor saline push-pull tests in fractured granite. It is possible to model density effects, but this leads to computational complexity and field dynamics that are not necessarily representative of the natural responses of the system. To minimize density effects, we performed a new set of push-pull tests using a neutrally buoyant and electrically conductive tracer at the same test site located close to Ploemeur, France. This novel tracer consists of a mixture of salt (NaCl), water and pure ethanol. Ethanol has a density of 789 g/L at 20° C and is used to counter-act the salt-induced density increase. Our GPR time-lapse images and tracer breakthrough data indicate a largely reversible transport process that confirms the neutral buoyancy of the tracer. Ethanol is biodegradable and does not pose significant environmental issues. Furthermore, calibration of the neutral-buoyant mixture is straightforward to perform in the field using Archimedes principle. Based on these results, we argue that neutrally buoyant ethanol-salt-water mixtures are ideal for a wide variety of hydrogeophysical tracer tests in porous or fractured media.

Community perceptions of home environments that lead children & youth to the street in semi-rural Kenya.

PubMed

Seidel, Sarah; Muciimi, James; Chang, James; Gitari, Stanley; Keiser, Philip; Goodman, Michael L

2018-05-28

Research with street-involved children and youth (SICY) in Sub-Saharan Africa over the past three decades has established a complex web of both micro and macro-level factors that simultaneously "push" and "pull" children and youth to the street. There is still little research with adult family and community members in communities from which SICY originate. Forty men and women from five semi-rural villages in Meru County, Kenya participated in a Rapid Rural Appraisal utilizing a fishbone diagram to explore main and underlying reasons for why children may be or may feel unwelcome in the home and thus migrate to the street. Responses were analyzed in terms of ecological levels, child or parent perspective, and the push/pull framework. Overall, community members identified families and households experiencing stress and lacking the necessary resources to successfully adjust and adapt. Four ecological levels of influence were proposed as main reasons, with parent and caregiver factors mentioned most often, followed by household factors, children's intrapersonal factors, and interpersonal (family) factors. Community and environmental level factors were also proposed as underlying factors. Analysis by gender revealed that both men and women emphasized push factors over pull factors, though men proposed more pull factors (from peers and street life) than women did. Men placed more responsibility on the children than women did, citing children's negative behaviors, dissatisfaction with home, and a desire for independence and work/income. Women, in contrast, emphasized children's feelings of being unloved and the experience of harsh punishment or abuse from caregivers. Findings suggest that interventions to reduce street involvement should support economically, medically, and psychologically vulnerable families and households through comprehensive family strengthening programs that build financial capacity, improve parenting and communication skills, and promote education over child work and labor. Copyright © 2018 Elsevier Ltd. All rights reserved.

Ideas from Future Technologies Workshop Held by ARL/TARDEC in Aberdeen Proving Ground, Maryland on 9-11 June, 1993

DTIC Science & Technology

1994-08-01

goalie moving his stick to block a puck. The first estimates of the predicted impact point may be available around 1 s before impact, and positioning...Innovation thrives in a "technology push" environment, not in a "demand pull " siruation. • Micromanagement is lethal to innovation. • Very few...strongest of "demand pull " conditions imaginable-a management method that reduces innovation. This could be counterbalanced with a strong "Tech Base

Push and pull models to manage patient consent and licensing of multimedia resources in digital repositories for case-based reasoning.

PubMed

Kononowicz, Andrzej A; Zary, Nabil; Davies, David; Heid, Jörn; Woodham, Luke; Hege, Inga

2011-01-01

Patient consents for distribution of multimedia constitute a significant element of medical case-based repositories in medicine. A technical challenge is posed by the right of patients to withdraw permission to disseminate their images or videos. A technical mechanism for spreading information about changes in multimedia usage licenses is sought. The authors gained their experience by developing and managing a large (>340 cases) repository of virtual patients within the European project eViP. The solution for dissemination of license status should reuse and extend existing metadata standards in medical education. Two methods: PUSH and PULL are described differing in the moment of update and the division of responsibilities between parties in the learning object exchange process. The authors recommend usage of the PUSH scenario because it is better adapted to legal requirements in many countries. It needs to be stressed that the solution is based on mutual trust of the exchange partners and therefore is most appropriate for use in educational alliances and consortia. It is hoped that the proposed models for exchanging consents and licensing information will become a crucial part of the technical frameworks for building case-based repositories.

A squeeze-type osmotic tablet for controlled delivery of nifedipine.

PubMed

Park, Jung Soo; Shin, Jun Hyun; Lee, Dong Hun; Kim, Moon Suk; Rhee, John M; Lee, Hai Bang; Khang, Gilson

2008-01-01

Osmotic delivery systems are based on osmotic driving force. Nifedipine tablets, available under the trade names Procardia XL (Pfizer) and Adalat (Bayer), are commercialized drug-delivery systems of an elemental osmotic pump that the push-pull osmotic tablet operates successfully in delivering water-insoluble drugs. For the improvement of the release pattern and the solubility of the drug, we developed a squeeze-type osmotic tablet (SQT) for nifedipine as a model drug. The SQT was composed of one or more ring type of squeeze-push layer (squeeze-disc) and a centered drug core. Squeeze-discs were stacked up with different physicochemical properties with gradient such as viscosity, swelling ratio and water absorption ratio using the osmotic agents from a disc of bottom to top. The present work investigated the effect of different preparation factors, such as hydrophilic polymers, the molecular weight of polymers, coating process, orifice size and types of excipient on release performance of nifedipine. With the purpose of delivering water-insoluble nifedipine at an approximate zero-order rate and step-function rate for 24 h, SQT has been successfully prepared, and significantly improved in the release rate and patterns in comparison with the Adalat push-pull system in vitro release features.

Pushed, pulled, or blocked? The elderly and the labor market in post-Soviet Russia.

PubMed

Gerber, Theodore P; Radl, Jonas

2014-05-01

Russia provides an interesting context for studying the labor market experiences of the elderly because of its experience with market transition, its looming growth in the elderly dependency ratio, and its unusual pension policies that do not penalize pensioners for working. We use data from twenty surveys of the Russian population conducted from February 1991 to November 2007 to analyze the labor market participation and earnings of elderly Russians following market transition. Economic desperation, exacerbated by low pension levels, pushed some elderly to seek employment for income on the labor market. Elderly Russians with more education had more opportunities to work, and education differentials increased as market reforms progressed. The correlates of earnings operate similarly for retirement- and pre-retirement age Russians, with several exceptions: unobserved factors favoring employment are negatively associated with earnings for the elderly, occupation mediates most of the effects of education, and patterns of change over time differ somewhat. Elderly Russians are not disproportionately blocked from employment following market reforms. Following the initial transition shock, their labor market activity increased. Overall, both push and pull factors shape the employment and earnings of the elderly, affecting different segments of them. Copyright © 2013 Elsevier Inc. All rights reserved.

The influence of the push-pull effect and a π-conjugated system in conversion efficiency of bis-chalcone compounds in a dye sensitized solar cell

NASA Astrophysics Data System (ADS)

Teo, Kien Yung; Tiong, Mee Hing; Wee, Hung Yee; Jasin, Nornadia; Liu, Zhi-Qiang; Shiu, Ming Yang; Tang, Jyun Yang; Tsai, Jenn-Kai; Rahamathullah, Rafizah; Khairul, Wan M.; Tay, Meng Guan

2017-09-01

Chalcone and its related compounds are known to be π-conjugated compounds, which can be potentially used in different electronic areas include dye sensitized solar cell (DSSC). A total of six bis-chalcone compounds (1-6) have been synthesized using a Claisen-Schmidt condensation method under basic conditions. The compounds were used as the dye in DSSC to test their solar conversion efficiency. In the process of solar cell fabrication, titanium(II) oxide (TiO2) coated glass was used as the working electrode, whereas the mixture of iodine (I2), lithium iodide (LiI), 4-tertbutylpyridine (4-TBP) and 1,2-dimethyl-3-propylimidazolium (DMPII) in 3-methoxypropionitrile were used as the electrolyte. The DSSC was fabricated by immersing the TiO2 glass into the respective bis-chalcone compound solution and dried into the oven at 45 °C for 120 min. Lastly, the working electrode and counter electrode were sealed using surlyn of 60 μm thickness. The efficiency test was conducted under AM 1.5G illumination with the incident light intensity of 100 mW/cm2. Among the six bis-chalcone derivatives, compound 2, namely 1,4-bis-2-hydroxychalcone, was recorded with the highest efficiency (0.054%) compared to the others (0.022-0.035%). The presence of a π-conjugated system and the push-pull effect in the molecule were found to enhance the conversion efficiency of DSSC. Details of the results are discussed in the present paper.

Simultaneous measurement at multiple depths of in situ rates of denitrification in the bed of a groundwater-fed river

NASA Astrophysics Data System (ADS)

Lansdown, Katrina; Trimmer, Mark; Heppell, Kate

2010-05-01

Typically characterised by steep chemical gradients and variable redox conditions, the hyporheic zone is considered a 'hotpot' or site of enhanced biogeochemical activity in the aquatic environment. As such the importance of the hyporheic zone for the attenuation of nutrients such as nitrate in a fluvial network has long been recognised. Controls on nitrogen transformations, however, especially at depths greater than 10cm below the sediment-water interface, remain comparatively less understood. Most work aimed at quantifying denitrification in the hyporheic zone has involved laboratory incubation of recovered sediments which is likely to affect the estimate of the true in situ rate. Results of such studies are usually cited as 'potential' rates of denitrification and have undoubtedly improved the understanding of nitrogen cycling in the aquatic environment. There is, however, a need for in situ measurement to improve our knowledge of nitrogen cycling in the river bed. Here, rates of denitrification in the hyporheic zone have been measured at multiple depths, simultaneously using 'push-pull' methodology (e.g. Snodgrass and Kitanidis 1998). The 'push-pull' technique involves injection of a solution containing reactant(s) (e.g. nitrate) and a conservative tracer (e.g. chloride) into the sediment and extraction of pore water samples over time. Recovered samples are screened for the removal of reactant(s) and/or the accumulation of products(s). Temporal changes in the conservative tracer are used to correct the concentration of the reactant(s) and product(s) for dispersion and advection. The disadvantage of the 'traditional' 'push-pull' methodology is that rates of nitrate removal are measured rather than rates of denitrification. In this research, comparison of measured and 'corrected' nitrate concentrations allowed the rate of nitrate removal (or production) to be quantified. In order to determine in situ rates of denitrification we used 15N-enriched nitrate as the reactant in the 'push-pull' experiments and measured the accumulation of 29N2 and 30N2 over time. Rates of denitrification were then calculated using the isotope pairing technique (as per Nielsen 1992; Sanders and Trimmer 2006). Measurements have been made at up to 40cm depth in the river bed using a miniprobe system developed from the design of Sanders and Trimmer (2006) in order to validate the experimental approach. Previous work conducted at the study site (R. Leith, Cumbria, UK) suggested than ambient conditions would not be ideal for in situ measurement of denitrification rates using 'push-pull' methodology. Slow rates of denitrification were measured during laboratory incubations of the sandy sediment (M. Trimmer, unpublished data), and the velocity of flow in the hyporheic zone would limit the duration of the in situ measurement (Käser et al. 2009). Despite difficulties posed by the site, we have measured in situ rates of denitrification at multiple depths in the hyporheic zone simultaneously. We also report measurement of in situ rates of denitrification below the zone of surface water - ground water mixing. In future we will use the experimental technique described in this paper to quantify (i) variation in N transformation rates with depth; and (ii) spatial variation in rates of nitrate consumption/production within the river bed. Käser, DH, Binley, A, Heathwaite, AL and Krause, S (2009) Spatio-temporal variations of hyporheic flow in a riffle-pool sequence. Hydrological Processes 23: 2138 - 2149. Nielsen, LP (1992) Denitrification in sediment determined from nitrogen isotope pairing. FEMS Microbiology Ecology 86: 357 - 362. Sanders, IA and Trimmer, M (2006) In situ application of the 15NO3- isotope pairing technique to measure denitrification in sediments at the surface water-groundwater interface. Limnology and oceanography: Methods 4: 142 - 152. Snodgrass, MF and Kitanidis, PK (1998) A method to infer in situ reaction rates from push-pull experiments. Ground Water 36(4): 645 - 650.

Antegrade jj stenting after percutaneous renal procedures: The 'pull and push' technique.

PubMed

Ratkal, Jaideep M; Sharma, Elias

2015-06-01

A JJ stent is inserted antegradely after percutaneous renal procedures like percutaneous nephrolithotomy (PCNL) for renal calculus disease, and for endopyelotomy for pelvi-ureteric junction obstruction. We describe a technique for antegrade stent insertion after PCNL.

Plasma Push and Pull

NASA Image and Video Library

2015-06-30

This still image from an animation from NASA GSFC Solar Dynamics Observatory shows dark strands of plasma hovering above the Sun surface beginning to interact with each other in a form of tug of war over two and a half days June 28-30, 2015.

Fractional Models Simulating Non-Fickian Behavior in Four-Stage Single-Well Push-Pull Tests

NASA Astrophysics Data System (ADS)

Chen, Kewei; Zhan, Hongbin; Yang, Qiang

2017-11-01

Four-stage single-well push-pull (SWPP) tracer tests, including injection, chasing, resting, and pumping, were conducted in a fractured aquifer at Newark basin. An anomalous transport phenomenon observed in the SWPP tests is the linear decline of breakthrough curves (BTCs) at late time with slope of -1.8 in log-log plots. A time-dependent fractional model is developed to interpret the anomalous transport behavior. This model considers a time-dependent power law memory function and a time-dependent fractional advection-dispersion operator. The fractional advection-dispersion equations (fADE) are solved in a radial coordinate system using the implicit Euler method. A semi-analytical solution of the first-order rate-limited mobile-immobile model (FORMIM) is derived for comparison. It is found that both the nonlocal transport in time and space can produce the long-tailed BTC. A smaller time-fractional or space-fractional index leads to a lower peak concentration and a larger late-time slope. The mass distribution of the fractional-in-space (FS) model exhibits power law decline at the leading plume edge. Early breakthrough during pumping is not observed because the mobile mass at the start of pumping is nonzero and more concentrated near the wellbore. The capacity ratio is an important factor that affects the peak concentration. A larger capacity ratio leads to greater peak concentration. A smaller time-fractional index in the injection, chasing, or resting stage will move the BTC downward and the slope of the late time BTC is determined by the space-fractional index over all stages and the time-fractional index in the pumping stage. The capability of the existing models to recover the BTC of the SWPP test is discussed and some guidelines for how to choose the appropriate model to interpret the SWPP test data are proposed.

A computerized test system for thermal-mechanical fatigue crack growth

NASA Technical Reports Server (NTRS)

Marchand, N.; Pelloux, R. M.

1986-01-01

A computerized testing system to measure fatigue crack growth under thermal-mechanical fatigue conditions is described. Built around a servohydraulic machine, the system is capable of a push-pull test under stress-controlled or strain-controlled conditions in the temperature range of 25 to 1050 C. Temperature and mechanical strain are independently controlled by the closed-loop system to simulate the complex inservice strain-temperature relationship. A d-c electrical potential method is used to measure crack growth rates. The correction procedure of the potential signal to take into account powerline and RF-induced noises and thermal changes is described. It is shown that the potential drop technique can be used for physical mechanism studies and for modelling crack tip processes.

Stress Prediction System

NASA Technical Reports Server (NTRS)

1995-01-01

NASA wanted to know how astronauts' bodies would react under various gravitational pulls and space suit weights. Under contract to NASA, the University of Michigan's Center for Ergonomics developed a model capable of predicting what type of stress and what degree of load a body could stand. The algorithm generated was commercialized with the ISTU (Isometric Strength Testing Unit) Functional Capacity Evaluation System, which simulates tasks such as lifting a heavy box or pushing a cart and evaluates the exertion expended. It also identifies the muscle group that limits the subject's performance. It is an effective tool of personnel evaluation, selection and job redesign.

Manufacturing Technology Support (MATES). Delivery Order 0002: Business Practices Assessment (BPA) Development

DTIC Science & Technology

2008-03-01

order fulfillment visibility, Kanban deployment, inventory count can be made visually, machines and tool labeling, costs, preventive maintenance...order fulfillment, computer scheduling versus Kanban , pull versus push systems, flow time efficiencies, back room costs of scheduling, MRP costs

Approaches and Concerns in Myanmar

ERIC Educational Resources Information Center

Mar, Naing Yee

2005-01-01

The information age has changed the economic and social environment in such ways that countries are moving from being "traditional pull" to "technology push" societies. This makes technical and vocational education and training (TVET) policy especially significant as it seeks to promote specialized practical and professional…

Nett Warrior C3Conflict Experiment: Measuring the Effect of Battlefield Awareness in Small Units

DTIC Science & Technology

2011-01-01

Top-level categories used to score the protocol of the soldiers’ text-based “chat” communications...17 Table 4. Subcategories for Pulls, Pushes, and Scripts used to score the protocol of the soldier’s chat

United States Air Force Research Initiation Program. 1984 Research Reports. Volume 3.

DTIC Science & Technology

1986-05-01

right terminal of lamp 13. Position the second switch below switch A such that the handle may be pulled toward you or pushed away from you. The second...position. 42. Pull the handle of s.itch B toward you to light lamp B. 47. Fush.the handle of switch B all the way forward to light both lamps A and B... goalI was to obtain information that could lead to the stabilization of a . Nd:YAG laser. III. APPROACH At the beginning of this research, some of the

Salt Marsh sediment 15N/13C "Push-Pull" assays reveal coupled sulfur, nitrogen, and carbon cycling

NASA Astrophysics Data System (ADS)

Thomas, S. M.; Tucker, J.; Thomas, F.; Sievert, S. M.; Cardon, Z. G.; Giblin, A. E.

2016-12-01

Salt marshes are extraordinarily productive ecosystems found in estuaries worldwide, hosting intensive sulfur, nitrogen, and carbon cycling. Although it has been hypothesized that in this environment sulfur oxidation may be important for energy flow, there is little direct data. At the heart of these hypothesized interactions are sulfur oxidizing microbes. Sulfur oxidizers can catalyze sulfide (re-)oxidation with nitrate as the electron acceptor under anaerobic conditions, producing ammonium (via DNRA) or dinitrogen gas (via denitrification). The form of sulfur present in marsh systems influences whether autotrophic or heterotrophic processes transform nitrate either to dinitrogen gas or ammonium through DNRA. To examine the fate of nitrate and interactions with sulfur, we conducted a series of "push-pull" experiments in marsh sediment at the Plum Island Ecosystems Long-Term Ecological Research site in Massachusetts. Porewater was extracted anoxically and amended with isotopically labeled nitrate (15N) and bicarbonate (13C). Porewater was pumped back into the sediment and then withdrawn at intervals of several hours. Dissolved inorganic nitrogen, sulfur, and carbon were measured as well as isotopes of nitrogen gas and ammonium. These push-pull experiments were conducted at several times during the growing season, to coincide with salt marsh grass initial growth (May), maximum growth (July), flowering (August), and senescence (October). Porewater sulfides were very low to non-detectable in May (time of initial plant growth) and increased to a maximum of 3 mM in October (time of plant senescence). Combined rates of denitrification and DNRA also varied seasonally: rates were higher in May (0.16 - 17.5 nmoles N/cm3/hr) and much lower in October (0 - 0.03 nmoles N/cm3/hr). Interestingly, DNRA rates were always higher than denitrification rates, often by an order of magnitude or more.

Optimal information transfer in enzymatic networks: A field theoretic formulation

NASA Astrophysics Data System (ADS)

Samanta, Himadri S.; Hinczewski, Michael; Thirumalai, D.

2017-07-01

Signaling in enzymatic networks is typically triggered by environmental fluctuations, resulting in a series of stochastic chemical reactions, leading to corruption of the signal by noise. For example, information flow is initiated by binding of extracellular ligands to receptors, which is transmitted through a cascade involving kinase-phosphatase stochastic chemical reactions. For a class of such networks, we develop a general field-theoretic approach to calculate the error in signal transmission as a function of an appropriate control variable. Application of the theory to a simple push-pull network, a module in the kinase-phosphatase cascade, recovers the exact results for error in signal transmission previously obtained using umbral calculus [Hinczewski and Thirumalai, Phys. Rev. X 4, 041017 (2014), 10.1103/PhysRevX.4.041017]. We illustrate the generality of the theory by studying the minimal errors in noise reduction in a reaction cascade with two connected push-pull modules. Such a cascade behaves as an effective three-species network with a pseudointermediate. In this case, optimal information transfer, resulting in the smallest square of the error between the input and output, occurs with a time delay, which is given by the inverse of the decay rate of the pseudointermediate. Surprisingly, in these examples the minimum error computed using simulations that take nonlinearities and discrete nature of molecules into account coincides with the predictions of a linear theory. In contrast, there are substantial deviations between simulations and predictions of the linear theory in error in signal propagation in an enzymatic push-pull network for a certain range of parameters. Inclusion of second-order perturbative corrections shows that differences between simulations and theoretical predictions are minimized. Our study establishes that a field theoretic formulation of stochastic biological signaling offers a systematic way to understand error propagation in networks of arbitrary complexity.

Evidence for -Gz Adaptation Observed with Wearable Biosensors During High Performance Jet Flight.

PubMed

Rice, G Merrill; Snider, Dallas; Moore, Jeffrey L; Lavan, J Timothy; Folga, Rich; VanBrunt, Thomas B

2016-12-01

Few studies have evaluated physiological responses to high acceleration forces during actual flight and to our knowledge no normative data has been acquired by technologies such as wearable biosensors during high performance jet aircraft operations. In-flight physiological data from an FDA cleared portable triaxial accelerometer and bio-sensor were observed from five active duty F-18 pilots of the Naval Flight Demonstration Squadron (Blue Angels). Of the five pilots, three were formation pilots who flew lower G profiles and two were solo pilots who flew higher G profiles. Physiological parameters monitored were heart rate, respiratory rate, temperature, caloric expenditure, and duration of exposure to levels of acceleration. Evaluated were 25 practice demonstration flights; 9 flights were excluded secondary to incomplete or inaccurate physiological data. We observed no significant bradycardia during a total of 189 maneuvers which met inclusion criteria for push-pull events (PPE) or isolated -Gz exposures. Further analysis of 73 PPE revealed an overall significant rise in HR following the PPE, where mean heart rate was 106 (95% CI, 100:112) at the beginning of the push and 129 (95% CI, 123:135) following the pull. A majority of the flights monitored provided reliable physiological data. Initial data suggests, contrary to currently held aeromedical doctrine, maneuvers such as the "push-pull" do not evoke vasovagal based bradycardic responses in aerobatic pilots. Possible explanations for these findings are sympathetic nervous system activation through adaptation and/or sustained isometric resistance from control inputs, both of which are areas of future research for our team.Rice GM, Snider D, Moore JL, Lavan JT, Folga R, VanBrunt TB. Evidence for -Gz adaptation observed with wearable biosensors during high performance jet flight. Aerosp Med Hum Perform. 2016; 87(12):996-1003.

Review on risk factors related to lower back disorders at workplace

NASA Astrophysics Data System (ADS)

A' Tifah Jaffar, Nur; Nasrull Abdol Rahman, Mohd

2017-08-01

This review examines the evidence of the occurrence of risk exposure on work-related lower back disorders in the workplace. This review also investigates potential interactions between the risk factors in the workplace which include heavy physical work risk factor, static work postures risk factor, frequent bending and twisting risk factor, lifting risk factor, pushing and pulling risk factor, repetitive work risk factor, vibration risk factor, psychological and psychosocial risk factor that may be associated with symptoms of musculoskeletal disorders of lower back. These risk factors can reinforce each other and their influence can also be mediated by cultural or social factors. A systematic review of the literature was carried out by searching using databases and the searching strategy was used combined keyword for risk factors, work-related lower back disorders, heavy physical work, static work postures, frequent bending and twisting, lifting, pushing and pulling, repetitive work, vibration, psychological and psychosocial risk factor. A total of 67 articles were identified and reviewed. The risk factors identified that related for low back disorder are seven which are heavy physical work, static work postures, frequent bending and twisting, lifting, pushing and pulling, repetitive work, vibration, psychological and psychosocial risk factor and the level of evidence supporting the relationship with lower back disorders also described such as strong, moderate, insufficient, limited and no evidence. This result confirms that, existing of higher physical and psychosocial demand related to reported risk factors of low back disorders. The result also showed that previous reviews had evaluated relationship between risk factors of low back disorders and specific types of musculoskeletal disorders. This review also highlights the scarves evidence regarding some of the frequently reported risk factors for work related lower back disorders.

Interpreting tracer breakthrough tailing from different forced-gradient tracer experiment configurations in fractured bedrock

USGS Publications Warehouse

Becker, M.W.; Shapiro, A.M.

2003-01-01

Conceptual and mathematical models are presented that explain tracer breakthrough tailing in the absence of significant matrix diffusion. Model predictions are compared to field results from radially convergent, weak-dipole, and push-pull tracer experiments conducted in a saturated crystalline bedrock. The models are based upon the assumption that flow is highly channelized, that the mass of tracer in a channel is proportional to the cube of the mean channel aperture, and the mean transport time in the channel is related to the square of the mean channel aperture. These models predict the consistent -2 straight line power law slope observed in breakthrough from radially convergent and weak-dipole tracer experiments and the variable straight line power law slope observed in push-pull tracer experiments with varying injection volumes. The power law breakthrough slope is predicted in the absence of matrix diffusion. A comparison of tracer experiments in which the flow field was reversed to those in which it was not indicates that the apparent dispersion in the breakthrough curve is partially reversible. We hypothesize that the observed breakthrough tailing is due to a combination of local hydrodynamic dispersion, which always increases in the direction of fluid velocity, and heterogeneous advection, which is partially reversed when the flow field is reversed. In spite of our attempt to account for heterogeneous advection using a multipath approach, a much smaller estimate of hydrodynamic dispersivity was obtained from push-pull experiments than from radially convergent or weak dipole experiments. These results suggest that although we can explain breakthrough tailing as an advective phenomenon, we cannot ignore the relationship between hydrodynamic dispersion and flow field geometry at this site. The design of the tracer experiment can severely impact the estimation of hydrodynamic dispersion and matrix diffusion in highly heterogeneous geologic media.

Biomechanical stability according to different configurations of screws and rods.

PubMed

Ha, Kee-Yong; Hwang, Sung-Chul; Whang, Tae-Hyuk

2013-05-01

Comparison of biomechanical strength according to 2 different configurations of screws and rods. To compare the biomechanical strength of different configurations of screws and rods composed of the same material and of the same size. Many complications related to instrumentation have been reported. The incidence of metallic failure would differ according to the materials and configurations of the assembly of the screws and rods used. However, to our knowledge, the biomechanical effects of implant assembly rods and screws with different configurations and different contours have not been reported. Biomechanical testing was conducted to compare top tightening (TT) screw-rod configuration with side tightening (ST) screw-rod configuration. All tests were conducted using a hydraulic all-purpose testing machine. All data were acquired at a rate of 10 Hz. Both screw systems used spinal rods of 6 mm diameter and were made of TiAl4V ELI material. Among 5 types of tests, 3 were conducted on the basis of American Society for Testing and Materials (ASTM) F 1798 to 97 and F1717-10. The other 2 tests were conducted for comparing the characteristics between TT and ST pedicle screws according to modified methods from ASTM F 1717-10 and ASTM F 1798-97. All results including axial gripping capacity and yield forces were obtained using the same methods on the basis of the mentioned ASTM standards. In the axial gripping capacity test, the mean axial gripping capacity of the TT screw-rod configuration was 3332 ± 118 N and that of ST was 2222 ± 147 N in straight rods (P = 0.019). In 15-degree contoured rods, TT was 2988 ± 199 N and ST was 2116 ± 423 N (P = 0.014). In 30-degree contoured rods, TT was 2227 ± 408 N and ST was 1814 ± 285 N (P = 0.009). In the pulling-out test, the pulling-out force of ST was 8695 ± 1616 N and that of TT was 6106 ± 195 N (P = 0.014). In the rod-pushing test, the failure force of ST was 4131 ± 205 N and that of TT was 5639 ± 105 N. In the compressive fatigue test, the maximum load was 145 N in ST and 119 N in TT. In the cycle fatigue test, the fatigue strength of ST was higher than that of TT. In the rod-pushing test, the failure force of ST was 4131 ± 205 N and that of TT was 5639 ± 105 N (P=0.046). Two different configurations of rod-screw systems found statistically significant differences with axial gripping, pulling out, and fatigue failures. ST constructs improved fixation stability over TT constructs. It was concluded that ST configuration may reduce complications related to implantation.

High frequency wide-band transformer uses coax to achieve high turn ratio and flat response

NASA Technical Reports Server (NTRS)

De Parry, T.

1966-01-01

Center-tap push-pull transformer with toroidal core helically wound with a single coaxial cable creates a high frequency wideband transformer. This transformer has a high-turn ratio, a high coupling coefficient, and a flat broadband response.

Vortex servovalve for fluidic or electrical input

NASA Technical Reports Server (NTRS)

Honda, T. S.

1972-01-01

Proportional-pressure control servovalve consisting of fluid amplifier bellows-driven jet-pipe and two vortex valves operating in push-pull, with a pair of bellows for pressure feedback is tolerant to comtaminant particles and meets minimum standby flow requirements for applications such as rocket thruster nozzles.

Monitoring of Au(iii) species in plants using a selective fluorescent probe.

PubMed

Li, Zhen; Xu, Yuqing; Fu, Jie; Zhu, Hailiang; Qian, Yong

2018-01-23

A colorimetric and ratiometric probe with a push-pull chromophore dicyanoisophorone system, AuP, has been developed for the detection of Au(iii) species with highly sensitive and selective response to real-water samples and living tissues of Arabidopsis thaliana.

Photoinduced Charge Shifts and Electron Transfer in Viologen-Tetraphenylborate Complexes: Push-Pull Character of the Exciplex.

PubMed

Santos, Willy G; Budkina, Darya S; Deflon, Victor M; Tarnovsky, Alexander N; Cardoso, Daniel R; Forbes, Malcolm D E

2017-06-14

Viologen-tetraarylborate ion-pair complexes were prepared and investigated by steady-state and time-resolved spectroscopic techniques such as fluorescence and femtosecond transient absorption. The results highlight a charge transfer transition that leads to changes in the viologen structure in the excited singlet state. Femtosecond transient absorption reveals the formation of excited-state absorption and stimulated emission bands assigned to the planar (k obs < 10 12 s -1 ) and twisted (k obs ∼ 10 10 s -1 ) structures between two pyridinium groups in the viologen ion. An efficient photoinduced electron transfer from the tetraphenylborate anionic moiety to the viologen dication was observed less than 1 μs after excitation. This is a consequence of the push-pull character of the electron donor twisted viologen structure, which helps formation of the borate triplet state. The borate triplet state is deactivated further via a second electron transfer process, generating viologen cation radical (V •+ ).

Technology Transfer: A Contact Sport

NASA Technical Reports Server (NTRS)

Paynter, Nina P.

1995-01-01

Technology transfer is a dynamic process, involving dynamic people as the bridge between NASA Langley Research Center and the outside world. This bridge, for nonaerospace applications, is known as the Technology Applications Group. The introduction of new innovations and expertise where they are needed occurs through a 'push' and 'pull' process. A 'push' occurs when a new technology is first developed with high commercial potential and then a company is found to licence or further develop the technology. The 'pull' process occurs through problem statements. A company or group will submit a written statement of what they need and the shortcomings of commercially available technology. The Technology Transfer Team (T3) reviews these problem statements and decides where NASA LaRC can offer assistance. A researcher or group of researchers are then identified who can help solve the problem and they are put in contact with the company. Depending upon the situation in either method, a Space Act Agreement (SAA), or outline of the responsibilities for each party, is developed.

Evaluation of localized muscle fatigue using power spectral density analysis of the electromyogram

NASA Technical Reports Server (NTRS)

Lafevers, E. V.

1974-01-01

Surface electromyograms (EMGs) taken from three upper torso muscles during a push-pull task were analyzed by a power spectral density technique to determine the operational feasibility of the technique for identifying changes in the EMGs resulting from muscular fatigue. The EMGs were taken from four subjects under two conditions (1) in shirtsleeves and (2) in a pressurized space suit. This study confirmed that frequency analysis of dynamic muscle activity is capable of providing reliable data for many industrial applications where fatigue may be of practical interest. The results showed significant effects of the pressurized space suit on the pattern of shirtsleeve fatigue responses of the muscles. The data also revealed (1) reliable differences between muscles in fatigue-induced responses to various locations in the reach envelope at which the subjects were required to perform the push-pull exercise and (2) the differential sensitivity of muscles to the various reach positions in terms of fatigue-related shifts in EMG power.

Learning to perceive haptic distance-to-break in the presence of friction.

PubMed

Altenhoff, Bliss M; Pagano, Christopher C; Kil, Irfan; Burg, Timothy C

2017-02-01

Two experiments employed attunement and calibration training to investigate whether observers are able to identify material break points in compliant materials through haptic force application. The task required participants to attune to a recently identified haptic invariant, distance-to-break (DTB), rather than haptic stimulation not related to the invariant, including friction. In the first experiment participants probed simulated force-displacement relationships (materials) under 3 levels of friction with the aim of pushing as far as possible into the materials without breaking them. In a second experiment a different set of participants pulled on the materials. Results revealed that participants are sensitive to DTB for both pushing and pulling, even in the presence of varying levels of friction, and this sensitivity can be improved through training. The results suggest that the simultaneous presence of friction may assist participants in perceiving DTB. Potential applications include the development of haptic training programs for minimally invasive (laparoscopic) surgery to reduce accidental tissue damage. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

High Efficiency push-pull class E amplifiers for fusion rocket engines

NASA Astrophysics Data System (ADS)

Gaitan, Gabriel; Ham, Eric; Cohen, S. A.; Swanson, Charles; Chen, Minjie; Brunkhorst, Christopher

2017-10-01

In a Field Reversed Configuration fusion reactor, ions in the plasma are heated by an antenna operating at RF frequencies. This paper presents how push-pull class E amplifiers can be used to efficiently drive this antenna in the MHz range, from 0.5MHz to 4 MHz, while maintaining low harmonic content in the output signal. We offer four different configurations that present a trade-off between efficiency and low harmonic content. The paper presents theoretical values and breadboard results from these configurations, which operate at a power of around 100W. For a practical design, multiple amplifiers would be linked in parallel and would power the RF antenna at around 1MW. These designs provide multiple different options for reactor systems that could be used in a variety of applications, from power plants on the ground to rocket engines in space. This work was supported, in part, by DOE Contract Number DE-AC02-09CH11466 and Princeton Environmental Institute.

Why are you draining your brain? Factors underlying decisions of graduating Lebanese medical students to migrate.

PubMed

Akl, Elie A; Maroun, Nancy; Major, Stella; Afif, Claude; Chahoud, Bechara; Choucair, Jacques; Sakr, Mazen; Schünemann, Holger J

2007-03-01

In the context of a worldwide physician brain drain phenomenon, Lebanon has the highest emigration factor in the Middle East and North Africa. In this manuscript we aim to identify and develop a conceptual framework for the factors underlying the decisions of graduating Lebanese medical students to train abroad. We conducted two focus groups and seven semi-structured individual interviews with 23 students. In the deductive analysis (based on the push-pull theory), students reported push factors in Lebanon and pull factors abroad related to five dimensions. They focused predominantly on how training abroad provides them with a competitive advantage in an oversaturated Lebanese job market. An inductive analysis revealed the following emerging concepts: repel factors abroad and retain factors locally; societal expectations that students should train abroad; marketing of abroad training; and an established culture of migration. The marketing of abroad training and the culture of migration are prevalent in the academic institutions.

Electroosmotic perfusion of tissue: sampling the extracellular space and quantitative assessment of membrane-bound enzyme activity in organotypic hippocampal slice cultures.

PubMed

Ou, Yangguang; Wu, Juanfang; Sandberg, Mats; Weber, Stephen G

2014-10-01

This review covers recent advances in sampling fluid from the extracellular space of brain tissue by electroosmosis (EO). Two techniques, EO sampling with a single fused-silica capillary and EO push-pull perfusion, have been developed. These tools were used to investigate the function of membrane-bound enzymes with outward-facing active sites, or ectoenzymes, in modulating the activity of the neuropeptides leu-enkephalin and galanin in organotypic-hippocampal-slice cultures (OHSCs). In addition, the approach was used to determine the endogenous concentration of a thiol, cysteamine, in OHSCs. We have also investigated the degradation of coenzyme A in the extracellular space. The approach provides information on ectoenzyme activity, including Michaelis constants, in tissue, which, as far as we are aware, has not been done before. On the basis of computational evidence, EO push-pull perfusion can distinguish ectoenzyme activity with a ~100 μm spatial resolution, which is important for studies of enzyme kinetics in adjacent regions of the rat hippocampus.

The Four-Ball Gyro and Motorcycle Countersteering

NASA Astrophysics Data System (ADS)

Galli, J. Ronald; Carroll, Bradley W.

2017-04-01

Most two-wheel motorcycle riders know that, at highway speeds, if you want to turn left you push on the left handlebar and pull on the right handlebar. This is called countersteering. Countersteering is counterintuitive since pushing left and pulling right when the front wheel is not spinning would turn the wheel to the right. All good motorcycle instructors teach countersteering but few understand the physics of why it works, even though there is considerable discussion about it among motorcycle riders. This paper gives a simplified explanation of gyroscopic precession and then applies this to the front wheel of a motorcycle using two steps: 1) explaining how the wheel's lean is initiated, and 2) explaining how the lean will cause the wheel to turn. To assist with this discussion and to demonstrate the conclusions, a "wheel" was constructed using copper pipe, a bicycle wheel hub, and one pound of lead in each of four "balls" at the end of the spokes (see Fig. 1).

A COCHLEAR MODEL USING THE TIME-AVERAGED LAGRANGIAN AND THE PUSH-PULL MECHANISM IN THE ORGAN OF CORTI.

PubMed

Yoon, Yongjin; Puria, Sunil; Steele, Charles R

2009-09-05

In our previous work, the basilar membrane velocity V(BM) for a gerbil cochlea was calculated and compared with physiological measurements. The calculated V(BM) showed excessive phase excursion and, in the active case, a best-frequency place shift of approximately two fifths of an octave higher. Here we introduce a refined model that uses the time-averaged Lagrangian for the conservative system to resolve the phase excursion issues. To improve the overestimated best-frequency place found in the previous feed-forward active model, we implement in the new model a push-pull mechanism from the outer hair cells and phalangeal process. Using this new model, the V(BM) for the gerbil cochlea was calculated and compared with animal measurements, The results show excellent agreement for mapping the location of the maximum response to frequency, while the agreement for the response at a fixed point as a function of frequency is excellent for the amplitude and good for the phase.

A COCHLEAR MODEL USING THE TIME-AVERAGED LAGRANGIAN AND THE PUSH-PULL MECHANISM IN THE ORGAN OF CORTI

PubMed Central

YOON, YONGJIN; PURIA, SUNIL; STEELE, CHARLES R.

2010-01-01

In our previous work, the basilar membrane velocity VBM for a gerbil cochlea was calculated and compared with physiological measurements. The calculated VBM showed excessive phase excursion and, in the active case, a best-frequency place shift of approximately two fifths of an octave higher. Here we introduce a refined model that uses the time-averaged Lagrangian for the conservative system to resolve the phase excursion issues. To improve the overestimated best-frequency place found in the previous feed-forward active model, we implement in the new model a push-pull mechanism from the outer hair cells and phalangeal process. Using this new model, the VBM for the gerbil cochlea was calculated and compared with animal measurements, The results show excellent agreement for mapping the location of the maximum response to frequency, while the agreement for the response at a fixed point as a function of frequency is excellent for the amplitude and good for the phase. PMID:20485540

Recovery in Level 7-10 Women's USA Artistic Gymnastics.

PubMed

Buckner, Stephen B; Bacon, Nicholas T; Bishop, Phillip A

2017-01-01

This study assessed physical performance in women's artistic gymnastics following three variable recovery periods. Participants included fifteen female gymnasts (mean age = 13.5 ± 1.1) who had competed at USA Gymnastics (USAG) levels 7 - 10 within at least one year prior to the study. Each testing session consisted of a warm-up followed by four muscular endurance tests and one explosive maximal test. Assessments included pull-ups, leg lifts, handstand push-ups, vertical jump, and push-ups. After the performance assessments, the participants completed a typical practice session. The performance measures were reassessed at the beginning of each of the recovery periods of 24, 48, and 72 hours in a counterbalanced design. Performance assessments were converted into Z-scores and then averaged for a composite session Z-score. The composite session Z-scores were compared to evaluate the recovery duration. Composite Z's were significantly lower (p=0.000), after the 24 (z=-1.10) and the 48 hour (z=-0.71) recovery periods compared to baseline (z=0.00). However, there was no difference in scores (p=1.00) between the baseline and 72 hours (z=0.004) recovery. Full recovery required 72 hours under the conditions of this study.

Physical and Biological Carbon Isotope Fractionation in Methane During Gas-Push-Pull-Tests

NASA Astrophysics Data System (ADS)

Gonzalez-Gil, G.; Schroth, M. H.; Gomez, K.; Zeyer, J.

2005-12-01

Stable isotope analyses have become a common tool to assess microbially-mediated processes in subsurface environments. We investigated if stable carbon isotope analysis can be used as a tool to complement gas push-pull tests (GPPTs), a novel technique that was recently developed and tested for the in-situ quantification of CH4 oxidation in soils. During a GPPT a gas mixture containing CH4, O2 and nonreactive tracer gases is injected into the soil, where CH4 is oxidized by indigenous microorganisms. Thereafter, a blend of injected gas mixture and soil air is extracted from the same location, and CH4 oxidation is quantified from an analysis of extracted CH4 and tracer gases. To assess the magnitude of physical isotope fractionation due to molecular diffusion during GPPTs, we conducted laboratory experiments in the absence of microbial activity in a 1m-high, 1m-diameter tank filled with dry sand. During the GPPTs' extraction phase, the isotopic composition of methane was analyzed. Results indicated strong carbon isotope fractionation (>20 per mil) during GPPTs. To assess the combined effect of physical and biological isotope fractionation, numerical simulations of GPPTs were conducted in which microbial CH4 isotope fractionation was simulated using first-order rate constants and microbial kinetic isotope fractionation factors previously reported for methane oxidation in landfill environments. Results of these simulations indicated that for small CH4 oxidation rates, overall isotope fractionation in CH4 is dominated by physical fractionation. Conversely, for high CH4 oxidation rates, overall fractionation is dominated by biological fractionation. Thus, CH4 isotope fractionation data alone from a single GPPT cannot be used to assess microbial CH4 oxidation. However, biological fractionation may be quantified if physical fractionation due to diffusion is known. This can be achieved by conducting two sequential GPPTs, with microbial activity being inhibited in the second test.

Association of activities of daily living with the load during step ascent motion in nursing home-residing elderly individuals.

PubMed

Masaki, Mitsuhiro; Ikezoe, Tome; Kamiya, Midori; Araki, Kojiro; Isono, Ryo; Kato, Takehiro; Kusano, Ken; Tanaka, Masayo; Sato, Syunsuke; Hirono, Tetsuya; Kita, Kiyoshi; Tsuboyama, Tadao; Ichihashi, Noriaki

2018-04-19

This study aimed to examine the association of independence in ADL with the loads during step ascent motion and other motor functions in 32 nursing home-residing elderly individuals. Independence in ADL was assessed by using the functional independence measure (FIM). The loads at the upper (i.e., pulling up) and lower (i.e., pushing up) levels during step ascent task was measured on a step ascent platform. Hip extensor, knee extensor, plantar flexor muscle, and quadriceps setting strengths; lower extremity agility using the stepping test; and hip and knee joint pain severities were measured. One-legged stance and functional reach distance for balance, and maximal walking speed, timed up-and-go (TUG) time, five-chair-stand time, and step ascent time were also measured to assess mobility. Stepwise regression analysis revealed that the load at pushing up during step ascent motion and TUG time were significant and independent determinants of FIM score. FIM score decreased with decreased the load at pushing up and increased TUG time. The study results suggest that depending on task specificity, both one step up task's push up peak load during step ascent motion and TUG, can partially explain ADL's FIM score in the nursing home-residing elderly individuals. Lower extremity muscle strength, agility, pain or balance measures did not add to the prediction.

Reaching out towards cannabis: approach-bias in heavy cannabis users predicts changes in cannabis use

PubMed Central

Cousijn, Janna; Goudriaan, Anna E; Wiers, Reinout W

2011-01-01

Aims Repeated drug exposure can lead to an approach-bias, i.e. the relatively automatically triggered tendencies to approach rather that avoid drug-related stimuli. Our main aim was to study this approach-bias in heavy cannabis users with the newly developed cannabis Approach Avoidance Task (cannabis-AAT) and to investigate the predictive relationship between an approach-bias for cannabis-related materials and levels of cannabis use, craving, and the course of cannabis use. Design, settings and participants Cross-sectional assessment and six-month follow-up in 32 heavy cannabis users and 39 non-using controls. Measurements Approach and avoidance action-tendencies towards cannabis and neutral images were assessed with the cannabis AAT. During the AAT, participants pulled or pushed a joystick in response to image orientation. To generate additional sense of approach or avoidance, pulling the joystick increased picture size while pushing decreased it. Craving was measured pre- and post-test with the multi-factorial Marijuana Craving Questionnaire (MCQ). Cannabis use frequencies and levels of dependence were measured at baseline and after a six-month follow-up. Findings Heavy cannabis users demonstrated an approach-bias for cannabis images, as compared to controls. The approach-bias predicted changes in cannabis use at six-month follow-up. The pre-test MCQ emotionality and expectancy factor were associated negatively with the approach-bias. No effects were found on levels of cannabis dependence. Conclusions Heavy cannabis users with a strong approach-bias for cannabis are more likely to increase their cannabis use. This approach-bias could be used as a predictor of the course of cannabis use to identify individuals at risk from increasing cannabis use. PMID:21518067

Characterizing Gas Transport in Wetland Soil-Root Systems with Dissolved Gas Tracer Techniques

NASA Astrophysics Data System (ADS)

Reid, M. C.; Jaffe, P. R.

2016-12-01

Soil fluxes of methane (CH4), nitrous oxide (N2O), and other biogenic gases depend on coupling between microbial and physiochemical processes within soil media. The importance of plant-mediated transport in wetland CH4 emissions is well known, but a generalized understanding of gas transfer between pore water and root aerenchyma, and how this process competes with biogeochemical production/consumption of gases beyond CH4, is incomplete [1]. A lack of experimental approaches to characterize transport processes in complex soil-water-plant systems at field scale has limited efforts to close this knowledge gap. In this presentation we describe dissolved gas tracer techniques to tease apart effects of transport from simultaneous biochemical reaction on trace gas dynamics in soils. We discuss a push-pull test with helium and sulfur hexafluoride gas tracers to quantify in situ root-mediated gas transfer kinetics in a wetland soil [2]. A Damköhler number analysis is introduced to interpret the results and evaluate the balance between biochemical reaction and root-driven gas transfer in controlling the fate of CH4 and N2O in vegetated wetland soils. We conclude with a brief discussion of other problems in soil gas dynamics that can be addressed with gas tracer approaches. [1] Blagodatsky and Smith 2012. Soil physics meets soil biology: Towards better mechanistic prediction of greenhouse gas emissions from soil. Soil Biology and Biochemistry 47, 78-92. [2] Reid et al. 2015. Dissolved gas dynamics in wetland soils: Root-mediated gas transfer kinetics determind via push-pull tracer tests. Water Resour. Res. 51, doi:10.1002/2014WR016803.

20 CFR 220.102 - Non-severe impairment(s), defined.

Code of Federal Regulations, 2010 CFR

2010-04-01

... significantly limit the claimant's physical or mental ability to do basic work activities. (b) Basic work activities. Basic work activities means the ability and aptitudes necessary to do most jobs. Examples of these include— (1) Physical functions such as walking, standing, sitting, lifting, pushing, pulling...

14 CFR 23.693 - Joints.

Code of Federal Regulations, 2011 CFR

2011-01-01

... STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Design and Construction Control Systems § 23.693 Joints. Control system joints (in push-pull systems) that are subject to angular motion... factor may be reduced to 2.0 for joints in cable control systems. For ball or roller bearings, the...

14 CFR 23.693 - Joints.

Code of Federal Regulations, 2010 CFR

2010-01-01

... STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Design and Construction Control Systems § 23.693 Joints. Control system joints (in push-pull systems) that are subject to angular motion... factor may be reduced to 2.0 for joints in cable control systems. For ball or roller bearings, the...

14 CFR 23.693 - Joints.

Code of Federal Regulations, 2012 CFR

2012-01-01

... STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Design and Construction Control Systems § 23.693 Joints. Control system joints (in push-pull systems) that are subject to angular motion... factor may be reduced to 2.0 for joints in cable control systems. For ball or roller bearings, the...

14 CFR 23.693 - Joints.

Code of Federal Regulations, 2014 CFR

2014-01-01

... STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Design and Construction Control Systems § 23.693 Joints. Control system joints (in push-pull systems) that are subject to angular motion... factor may be reduced to 2.0 for joints in cable control systems. For ball or roller bearings, the...

Pull and Push in Educational Innovation: Study of an Interfaculty Programme.

ERIC Educational Resources Information Center

Barnett, S. A.; Brown, Valerie A.

1981-01-01

A multidisciplinary, holistic course was introduced at the Australian National University to relate scientific evidence to the demands of decision making and problem solving. Student participants are shown to improve in independent judgment and decline in dogmatism. Program design and implementation are discussed. (MSE)

Spatial repellents and attractants as components of a "push-pull" management strategy

USDA-ARS?s Scientific Manuscript database

This presentation was an overview of research efforts being conducted by the Mosquito and Fly Research Unit (MFRU) of the United States Department of Agriculture (USDA), Center for Medical and Veterinary Entomology (CMAVE) located in Gainesville, Florida, to develop innovative population management...

CIVET: Continuous Integration, Verification, Enhancement, and Testing

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

Alger, Brian; Gaston, Derek R.; Permann, Cody J

A Git server (GitHub, GitLab, BitBucket) sends event notifications to the Civet server. These are either a " Pull Request" or a "Push" notification. Civet then checks the database to determine what tests need to be run and marks them as ready to run. Civet clients, running on dedicated machines, query the server for available jobs that are ready to run. When a client gets a job it executes the scripts attached to the job and report back to the server the output and exit status. When the client updates the server, the server will also update the Git servermore » with the result of the job, as well as updating the main web page.« less

Low cycle fatigue properties of type 316 stainless steel in vacuum

NASA Astrophysics Data System (ADS)

Furuya, Kazuo; Nagata, Norio; Watanabe, Ryoji

1980-04-01

Low cycle fatigue tests in vacuum were carried out on Type 316 stainless steel under the push-pull type, strain-controlled, continuous cycling mode in the temperature range from room temperature to 1073 K and strain rate from 5 × 10 -3 to 5 × 10 -5/s . Little temperature dependence of the fatigue life at a given plastic strain range is observed. The fatigue life decreases with decreasing strain rate at room temperature and 823 K, but shows little change at 973 and 1073 K. The fracture mode is transgranular in most cases, but an indication of intergranular cracking is observed in the specimens tested at 1073 K and at the lowest strain rate. The results are treated by the general adsorption model.

Returnees and Diaspora as Source of Innovation in Chinese Higher Education

ERIC Educational Resources Information Center

Welch, Anthony; Hao, Jie

2013-01-01

This paper highlights how returnees and knowledge diaspora are important sources for China's human resources development, identifying push and pull factors that also contribute significantly to innovation in the higher education sector. By outlining China's key projects and schemes for recruiting international professional workers, the paper…

Large First Hyperpolarizabilities in Push-Pull Polyenes by Tuning Bond Length Alternation and Aromaticity

NASA Technical Reports Server (NTRS)

Marder, S. R.; Tiemann, B. G.; Friedli, A. C.; Cheng, L. -T.; Blanchard-Desce, M.

1993-01-01

Conjugated organic compounds with 3-phenyl-5-isoxazolone, or N, N'-diethylthiobarbituric acid acceptors have large first molecular hyperpolarizabilities in comparison to compounds with 4-nitrophenyl acceptors as measured by electric feld induced second harmonic generation, (EFISH), in chloroform, with 1.907 micron fundamental radiation.

29 CFR 1926.1053 - Ladders.

Code of Federal Regulations, 2012 CFR

2012-07-01

... ascend or descend without continually having to hold, push or pull any part of the device, leaving both... the carrier. When the system is exposed to wind, cable guides for flexible carriers shall be installed... mountings and cable guides shall not reduce the design strength of the ladder. (24) The side rails of...

29 CFR 1926.1053 - Ladders.

Code of Federal Regulations, 2013 CFR

2013-07-01

... ascend or descend without continually having to hold, push or pull any part of the device, leaving both... the carrier. When the system is exposed to wind, cable guides for flexible carriers shall be installed... mountings and cable guides shall not reduce the design strength of the ladder. (24) The side rails of...

Entrepreneurship Policy for University Students: A Case Study of Zhejiang Province

ERIC Educational Resources Information Center

Mei, Weihui

2012-01-01

Cultivating university students' entrepreneurial skills has become a worldwide common interest. Taking Zhejiang Province, China as a case, this paper firstly analyses the push and the pull forces of cultivating innovative and entrepreneurial talents. Then the contents of Zhejiang's entrepreneurship policy for university students are systematically…

Insights from Teacher Leavers: Push and Pull in Career Development

ERIC Educational Resources Information Center

Rinke, Carol R.; Mawhinney, Lynnette

2017-01-01

This article examines the career pathways of US teacher leavers, individuals who have voluntarily left classroom teaching prior to retirement. Based on the perspective that teachers construct their own career pathways through an ongoing negotiation among intrinsic and extrinsic factors, this research captures the experiences of 24 teacher leavers…

Directional Flow of Summer Aeration to Manage Insect Pests in Stored Wheat

USDA-ARS?s Scientific Manuscript database

Field trials were conducted in metal wheat storage bins to determine whether pressure aeration, pushing ambient air from the bottom, or suction aeration, pulling air down from the top, would be more efficient at cooling the wheat mass and thereby limiting insect population growth. Aeration was accom...

Evaluating a push-pull strategy for management of Drosophila suzukii Matsumura in red raspberry

USDA-ARS?s Scientific Manuscript database

Drosophilia suzukii Matsumura is a serious pest of small fruits and cherries that lays its eggs in ripe and ripening fruit. Current management strategies rely on an unsustainable schedule of foliar applications of chemical insecticides. Alternative approaches to suppressing oviposition are under inv...

Officer Career Development: A Review of the Civilian and Military Research Literature on Turnover and Retention

DTIC Science & Technology

1991-09-01

balance of costs associated with turnover and the costs associated with retaining employees. Under this approach, the optimal level of aggregate turnover...behavior psychiatric technicians psychological attachment push/pull models quality of life quality of service quality of worklife questionnaires race

Romanians Abroad: A Snapshot of Highly Skilled Migration

ERIC Educational Resources Information Center

Ferro, Anna

2004-01-01

This paper is about the experience of labour migration among skilled Romanians, mainly Information Technology workers and highly qualified researchers. It is based on a questionnaire survey where, among other elements, the researcher investigated the push-pull aspects of qualified migration and the strategies of labour migration. This paper…

On Being More Accountable: The Push and Pull of Risk in School Leadership

ERIC Educational Resources Information Center

McWilliam, Erica; Perry, Lea-Anne

2006-01-01

This article addresses risk and its minimization as a powerful rationality for driving leadership practices in contemporary schools. It explores risk-consciousness as "a moral climate of politics" (Giddens 2002) and as a management imperative that impacts on any contemporary organization, including schools. The impact of…

A semiochemical-based push-pull management strategy for pepper weevil

USDA-ARS?s Scientific Manuscript database

The pepper weevil Anthonomus eugeenii is a serious pest on peppers in southern United States. The weevils lay their eggs in flower buds and immature fruit where the larvae feed on the developing seed. Consequently, infestations are hard to control by pesticide applications. The aggregation pheromo...

Management, Entrepreneurship and Private Service Orientation: A Framework for Undergraduate Veterinary Education

ERIC Educational Resources Information Center

Sasidhar, P. V. K.; Van Den Ban, Anne W.

2006-01-01

The changing nature of livestock outreach service delivery, manpower requirements and opportunities in the private sector provide both push and pull dynamics for veterinary graduates to engage in managerial, entrepreneurial, public and private service activities. The veterinary schools should support this transition by integrating Managerial,…

Are We Ready for the Virtual Library? Technology Push, Market Pull and Organisational Response.

ERIC Educational Resources Information Center

Gilbert, J. D.

1993-01-01

Discusses virtual libraries, i.e., library services available to users via personal computers; considers the issues of technological development, user demands, and organizational response; and describes progress toward virtual libraries in the Netherlands, including networks, online systems, navigation tools, subject classification, coordination…

Student Mobility and Doctoral Education in South Africa

ERIC Educational Resources Information Center

Sehoole, Chika Trevor

2011-01-01

This article analyses doctoral education programmes in South Africa with a particular focus on student mobility. It investigates pull and push factors as a conceptual framework, arguing that the patterns of student mobility in doctoral education programmes in South Africa follow the patterns of international student mobility elsewhere, which are…

Making Pop Bottle Rockets

ERIC Educational Resources Information Center

Lowe, Graham

2005-01-01

Teaching about forces provides a good opportunity to encourage children to start thinking about energy transfer. Children come into the classroom with a number of ideas about the nature of energy. These often become apparent when eliciting their ideas about forces, particularly when discussing "push" and "pull". In this article, the author…

Rhizomatic Explorations in Curriculum

ERIC Educational Resources Information Center

Smitka, Julie A. M.

2012-01-01

A visual and theatrical exercise anchored in the Grades 11 and 12 Ontario Curriculum for Media Arts and Interdisciplinary Studies was enacted and recorded as individual experiences of each participant. The event was re-mastered in a graphic representation that depicts the forces, pushes and pulls of curriculum and students' needs which educators…

Novel approaches using Push-Pull strategy for stable fly control

USDA-ARS?s Scientific Manuscript database

The stable fly, Stomoxys calcitrans, has been considered as the most important insect pest of cattle in the United States. The negative impacts of biting result in significant weight loss and milk production, which attribute to huge economic losses in cattle industry. The control of this pest heavil...

A Fragile Birth

ERIC Educational Resources Information Center

Desrochers, Lindsay A.

2007-01-01

The project of building the tenth University of California (UC) campus--UC Merced--was a lightning rod for all the various pushes and pulls in California society between 1983 and 2005. In fact, the author suggests, the project provides a clear window into California during this period. In this chapter, she describes the political and economic…

Development of a miniaturized hour-glass shaped fatigue specimen

NASA Astrophysics Data System (ADS)

Miwa, Y.; Jitsukawa, S.; Hishinuma, A.

1998-10-01

Diametral strain-controlled push-pull fatigue tests with zero mean strain were carried out with miniaturized hour-glass shaped specimens of an austenitic stainless steel in solution annealed condition at room temperature. The specimens had a diameter of 1.25 mm at the minimum cross section and a total length of 25.4 mm. The number of cycles to failure ( Nf) was equal to or slightly greater than that obtained with standard size specimens. Nf was also revealed to be rather insensitive to the specimen load axis offset, indicating that the requirement of the specimen alignment to the load axis was not very severe for the miniaturized specimen.

The Resonating Arm Exerciser: design and pilot testing of a mechanically passive rehabilitation device that mimics robotic active assistance

PubMed Central

2013-01-01

Background Robotic arm therapy devices that incorporate actuated assistance can enhance arm recovery, motivate patients to practice, and allow therapists to deliver semi-autonomous training. However, because such devices are often complex and actively apply forces, they have not achieved widespread use in rehabilitation clinics or at home. This paper describes the design and pilot testing of a simple, mechanically passive device that provides robot-like assistance for active arm training using the principle of mechanical resonance. Methods The Resonating Arm Exerciser (RAE) consists of a lever that attaches to the push rim of a wheelchair, a forearm support, and an elastic band that stores energy. Patients push and pull on the lever to roll the wheelchair back and forth by about 20 cm around a neutral position. We performed two separate pilot studies of the device. In the first, we tested whether the predicted resonant properties of RAE amplified a user’s arm mobility by comparing his or her active range of motion (AROM) in the device achieved during a single, sustained push and pull to the AROM achieved during rocking. In a second pilot study designed to test the therapeutic potential of the device, eight participants with chronic stroke (35 ± 24 months since injury) and a mean, stable, initial upper extremity Fugl-Meyer (FM) score of 17 ± 8 / 66 exercised with RAE for eight 45 minute sessions over three weeks. The primary outcome measure was the average AROM measured with a tilt sensor during a one minute test, and the secondary outcome measures were the FM score and the visual analog scale for arm pain. Results In the first pilot study, we found people with a severe motor impairment after stroke intuitively found the resonant frequency of the chair, and the mechanical resonance of RAE amplified their arm AROM by a factor of about 2. In the second pilot study, AROM increased by 66% ± 20% (p = 0.003). The mean FM score increase was 8.5 ± 4 pts (p = 0.009). Subjects did not report discomfort or an increase in arm pain with rocking. Improvements were sustained at three months. Conclusions These results demonstrate that a simple mechanical device that snaps onto a manual wheelchair can use resonance to assist arm training, and that such training shows potential for safely increasing arm movement ability for people with severe chronic hemiparetic stroke. PMID:23597303

The Resonating Arm Exerciser: design and pilot testing of a mechanically passive rehabilitation device that mimics robotic active assistance.

PubMed

Zondervan, Daniel K; Palafox, Lorena; Hernandez, Jorge; Reinkensmeyer, David J

2013-04-18

Robotic arm therapy devices that incorporate actuated assistance can enhance arm recovery, motivate patients to practice, and allow therapists to deliver semi-autonomous training. However, because such devices are often complex and actively apply forces, they have not achieved widespread use in rehabilitation clinics or at home. This paper describes the design and pilot testing of a simple, mechanically passive device that provides robot-like assistance for active arm training using the principle of mechanical resonance. The Resonating Arm Exerciser (RAE) consists of a lever that attaches to the push rim of a wheelchair, a forearm support, and an elastic band that stores energy. Patients push and pull on the lever to roll the wheelchair back and forth by about 20 cm around a neutral position. We performed two separate pilot studies of the device. In the first, we tested whether the predicted resonant properties of RAE amplified a user's arm mobility by comparing his or her active range of motion (AROM) in the device achieved during a single, sustained push and pull to the AROM achieved during rocking. In a second pilot study designed to test the therapeutic potential of the device, eight participants with chronic stroke (35 ± 24 months since injury) and a mean, stable, initial upper extremity Fugl-Meyer (FM) score of 17 ± 8 / 66 exercised with RAE for eight 45 minute sessions over three weeks. The primary outcome measure was the average AROM measured with a tilt sensor during a one minute test, and the secondary outcome measures were the FM score and the visual analog scale for arm pain. In the first pilot study, we found people with a severe motor impairment after stroke intuitively found the resonant frequency of the chair, and the mechanical resonance of RAE amplified their arm AROM by a factor of about 2. In the second pilot study, AROM increased by 66% ± 20% (p = 0.003). The mean FM score increase was 8.5 ± 4 pts (p = 0.009). Subjects did not report discomfort or an increase in arm pain with rocking. Improvements were sustained at three months. These results demonstrate that a simple mechanical device that snaps onto a manual wheelchair can use resonance to assist arm training, and that such training shows potential for safely increasing arm movement ability for people with severe chronic hemiparetic stroke.

Metropolitan area networks: a corner stone in the broadband era

NASA Astrophysics Data System (ADS)

Ghanem, Adel

1991-02-01

Deployment of Broadband ISDN is being influenced by both a market pull and a technology push. New broadband service opportunities exist in the business and residential sectors of the market place. It is envisioned that some customers will need connections directly to broadband switches because of the high bandwidth needed for their applications. At the same time Metropolitan Area Network (MAN) systems will serve those customers with bandwidth requirements less than or equal to 150 Mbps. A given MAN will have a geographical domain to serve where it will carry out the switching tasks within this domain. While MANs couldbe designed using differentarchitecturalconcepts the setofservices expected tobeprovidedby MANs could be equivalent to thelist ofservices thatwillbe supported by the targetbroadband network. This paperpositions MANs as a major building block for Broadband networks. It also examines the evolution process ofMANs as a needed step to assure the successful deployment of these new broadband services. 2. BISDN - OVERVIEW Broadband ISDN (BISDN) is being driven into existence by both a market pull as well as a technology push. Opportunities for new valueadded services are the prime market pull for future broadband networks. These services opportunities extend beyond simple voice and low speed data applications and cover both the residential and the business sectors of the market. It is noted for instance that business customers have growing needs for sophisticated telecommunication vehicles to support their

Interface modification during oxidation of a glass-ceramic matrix/SiC fibre composite

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

Daniel, A.M.; Martin-Meizoso, A.; Plucknett, K.P.

Oxidation heat treatments between 375{degrees}C and 600{degrees}C for 100 hours in air, have been performed on the calcium aluminosilicate glass-ceramic matrix/SiC fibre reinforced composite CAS/Nicalon (manufactured by Corning, USA). Using a commercial nano-indentation system to perform fibre push-down tests, the fibre-matrix interfacial debond fracture surface energy (G{sub i}) and frictional shear stress ({tau}) have been determined. Modification of interface properties, compared to the as-fabricated material, was observed at heat treatment temperatures as low as 375{degrees}C, where a significant drop in G{sub i} and an increase in {tau} were recorded. With 450{degrees}C, 525{degrees}C and 600{degrees}C heat treatments, an increase in G{submore » i} but a dramatic increase in {tau} were recorded. Under four-point flexure testing, the as fabricated and the 375{degrees}C heat treated materials displayed tough, composite behaviour with extensive fibre pull out, but at {ge}450{degrees}C, brittle failure with minimal fibre pull out, was observed. This transition from tough mechanical response to one of brittleness is due to the large increase in {tau} reducing fibre pull out to a minimum and therefore reducing the total required work of fracture. The large increases in {tau} and G{sub i} have been attributed to the oxidative removal of the lubricating, carbon interface and the compressive residual stresses across the interface.« less

Interface modification during oxidation of a glass-ceramic matrix/SiC fibre composite

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

Daniel, A.M.; Martin-Meizoso, A.; Plucknett, K.P.

Oxidation heat treatments between 375{degrees}C and 600{degrees}C for 100 hours in air, have been performed on the calcium aluminosilicate glass-ceramic matrix/SiC fibre reinforced composite CAS/Nicalon (manufactured by Coming, USA). Using a commercial nano-indentation system to perform fibre push-down tests, the fibre-matrix interfacial debond fracture surface energy (G{sub i}) and frictional shear stress ({tau}) have been determined. Modification of interface properties, compared to the as fabricated material, was observed at heat treatment temperatures as low as 375{degrees}C, where a significant drop in G{sub i} and an increase in {tau} were recorded. With 450{degrees}C, 525{degrees}C and 600{degrees}C heat treatments, an increase inmore » G{sub i} but a dramatic increase in {tau} were recorded. Under four-point flexure testing, the as fabricated and the 375{degrees}C heat treated materials displayed tough, composite behaviour with extensive fibre pull out, but at {le}450{degrees}C, brittle failure with minimal fibre pull out, was observed. This transition from tough mechanical response to one of brittleness is due to the large increase in {tau} reducing fibre pull out to a minimum and therefore reducing the total required work of fracture. The large increases in {tau} and G{sub i} have been attributed to the oxidative removal of the lubricating, carbon interface and the compressive residual stresses across the interface.« less

Cooperative data dissemination to mission sites

NASA Astrophysics Data System (ADS)

Chen, Fangfei; Johnson, Matthew P.; Bar-Noy, Amotz; La Porta, Thomas F.

2010-04-01

Timely dissemination of information to mobile users is vital in many applications. In a critical situation, no network infrastructure may be available for use in dissemination, over and above the on-board storage capability of the mobile users themselves. We consider the following specialized content distribution application: a group of users equipped with wireless devices build an ad hoc network in order cooperatively to retrieve information from certain regions (the mission sites). Each user requires access to some set of information items originating from sources lying within a region. Each user desires low-latency access to its desired data items, upon request (i.e., when pulled). In order to minimize average response time, we allow users to pull data either directly from sources or, when possible, from other nearby users who have already pulled, and continue to carry, the desired data items. That is, we allow for data to be pushed to one user and then pulled by one or more additional users. The total latency experienced by a user vis-vis a certain data item is then in general a combination of the push delay and the pull delay. We assume each delay time is a function of the hop distance between the pair of points in question. Our goal in this paper is to assign data to mobile users, in order to minimize the total cost and the average latency experienced by all the users. In a static setting, we solve this problem in two different schemes, one of which is easy to solve but wasteful, one of which relates to NP-hard problems but is less so. Then in a dynamic setting, we adapt the algorithm for the static setting and develop a new algorithm with respect to users' gradual arrival. In the end we show a trade-off can be made between minimizing the cost and latency.

Phase-dependent organization of postural adjustments associated with arm movements while walking.

PubMed

Nashner, L M; Forssberg, H

1986-06-01

This study examines the interactions between anteroposterior postural responses and the control of walking in human subjects. In the experimental paradigm, subjects walked upon a treadmill, gripping a rigid handle with one hand. Postural responses at different phases of stepping were elicited by rapid arm pulls or pushes against the handle. During arm movements, EMG's recorded the activity of representative arm, ankle, and thigh segment muscles. Strain gauges in the handle measured the force of the arm movement. A Selspot II system measured kinematics of the stepping movements. The duration of support and swing phases were marked by heel and toe switches in the soles of the subjects' shoes. In the first experiment, subjects were instructed to pull on the handle at their own pace. In these trials all subjects preferred to initiate pulls near heel strikes. Next, when instructed to pull as rapidly as possible in response to tone stimuli, reaction times were similar for all phases of the step cycle. Leg muscle responses associated with arm pulls and pushes, referred to as "postural activations," were directionally specific and preceded arm muscle activity. The temporal order and spatial distribution of postural activations in the muscles of the support leg were similar when arm pull movements occurred while the subject was standing in place and after heel strike while walking. Activations began in the ankle and radiated proximally to the thigh and then the arm. Activations of swing leg muscles were also directionally specific and involved flexion and forward or backward thrust of the limb. When arm movements were initiated during transitions from support by one leg to the other, patterns of postural activations were altered. Alterations usually occurred 10-20 ms before hell strikes and involved changes in the timing and sometimes the spatial structure of postural activations. Postural activation patterns are similar during in-place standing and during the support phase of locomotion. Walking and posture control appear to be separately organized but interrelated activities. Our results also suggest that the stepping generators, not peripheral feedback time locked to heel strikes, modulate postural activation patterns.

From Research to Flight: Surviving the TRL Valley of Death for Robotic and Human Exploration

NASA Technical Reports Server (NTRS)

Johnson, Les

2009-01-01

Fundamental research is critical to taking the next giant leap in the scientific exploration of space. NASA should be pushing the envelope and asking "what if?" .. Technology push enables new capabilities. When NASA began, everything was enabling. .. Technology pull is often required to meet current mission requirements. Technology management requires more than issuing NRAs and overseeing contracts. Continuous assessment, peer review, and system systems studies are vital to credible TRL advancement. A strategy for taking technology R&D to new heights will lead to discoveries at far-reaching destinations..

Explaining Australian immigration.

PubMed

Betts, K

1996-11-01

"This article reviews the post-Second World War literature on explanations for Australia's immigration program. It discovers three main schools of thought based on net pull factors: the official explanation and two unofficial explanations which focus on migrants as workers and on migrants as consumers. However the growing importance of net push factors after 1974 means that some of this work is less relevant today. Explanations focusing on net push factors have yet to cohere into a distinct perspective (or perspectives) but some research has been done on chain migration and family-based migration strategies, asylum seekers, temporary movement, and migration and the law." excerpt

In-Situ 13C-Labeling of Microbial Phospholipid Fatty Acids: Tracing Substrate Assimilation in a Petroleum-Contaminated Aquifer

NASA Astrophysics Data System (ADS)

Pombo, S. A.; Schroth, M. H.; Pelz, O.; Zeyer, J.

2001-12-01

Stable isotope analysis of phospholipid-derived fatty acids (PLFA) is a novel tool to trace assimilation of organic carbon in microbial communities. The 13C-labeling of biomarker fatty acids allows the identification of specific microbial populations involved in the metabolism of particular substrates, supplemented in 13C-labeled form. The goal of this study was to investigate the feasibility of 13C-labeling of PLFA and produced dissolved inorganic carbon (DIC) in a petroleum hydrocarbon (PHC)-contaminated aquifer during an in-situ experiment. To this end, we performed a single-well "push-pull" test in a monitoring well located in the denitrifying zone of a PHC-contaminated aquifer in Studen, Switzerland. During the experiment, we injected 500 L of site groundwater that was amended with 13C-labeled acetate (50% [2-13C]) and nitrate as reactants, and bromide as conservative tracer. Following the injection, we extracted a total of 1000 L of test solution/groundwater mixture after 4, 23 and 46 h from the same location. Concentrations of anions were measured in samples collected during the extraction. From these data, we computed first order rate coefficients for consumption of acetate (0.70 +/- 0.05 1/d) and nitrate (0.63 +/- 0.08 1/d). In addition, we extracted and identified PLFA, and measured \\delta13C values of PLFA and DIC. After only 4 h of incubation, we detected 13C-enrichment of certain PLFA in suspended biomass of extracted groundwater. After 46 h, we measured enrichments of up to 5000 per mil in certain PLFA (e.g. 16:1ω 7c), and up to 1500 per mil in the produced DIC. Our results demonstrate the feasibility of in-situ 13C-labeling of PLFA and DIC using push-pull tests to determine microbial activities in-situ in a natural ecosystem.

Flight and Wind-tunnel Tests of an XBM-1 Dive Bomber

NASA Technical Reports Server (NTRS)

Donely, Philip; Pearson, Henry A

1938-01-01

Results are given of pressure-distribution measurements made in flight over the right wing cellule and the right half of the horizontal tail surfaces of a dive-bombing biplane. Simultaneous measurements were also taken of the air speed, control-surface positions, control forces, and normal accelerations during various abrupt maneuvers in vertical plane. These maneuvers consisted of push-downs and pull-ups from level flight, dives and dive pull-ups from inverted flight. Besides the pressure measurements, flight tests were made to obtain (1) wing-fabric deflections during dives and (2) variation of the minimum drag coefficient with Reynolds Number. Supplementary tests were also done in the full-scale wind tunnel to obtain the characteristics of the airplane under various propeller conditions and with various tail settings. The results indicate that: (1) by increasing the fabric deflection between pressure ribs, the span load distribution was considerably modified near the center and the wing moment relations were changed; and (2) the minimum drag was less for the idling propeller than for the propeller locked in a vertical position. The value of C(sub D sub min) was equal to K(Reynolds Number)(exp -0.03) for a range from 2,800,000 to 13,100,000.

Procedure Selection and Patient Positioning Influence Spine Kinematics During High-Velocity, Low-Amplitude Spinal Manipulation Applied to the Low Back.

PubMed

Bell, Spencer; D'Angelo, Kevin; Kawchuk, Gregory N; Triano, John J; Howarth, Samuel J

This investigation compared indirect 3-dimensional angular kinematics (position, velocity, and acceleration) of the lumbar spine for 2 different high-velocity, low-amplitude (HVLA) spinal manipulation procedures (lumbar spinous pull or push), and altered initial patient lower limb posture. Twenty-four participants underwent 6 HVLA procedures directed toward the presumed L4 vertebra, reflecting each combination of 2 variants of a spinal manipulation application technique (spinous pull and push) and 3 initial hip flexion angles (0°, 45°, and 90°) applied using a right lateral recumbent patient position. All contact forces and moments between the patient and the external environment, as well as 3-dimensional kinematics of the patient's pelvis and thorax, were recorded. Lumbar spine angular positions, velocities, and accelerations were analyzed within the preload and impulse stages of each HVLA trial. Lumbar spine left axial rotation was greater for the pull HVLA. The pull HVLA also generated a greater maximum (leftward) and lower minimum (rightward) axial rotation velocity and deceleration and greater leftward and rightward lateral bend velocities, acceleration, and deceleration components. Not flexing the hip produced the greatest amount of extension, as well as the lowest axial rotation and maximum axial rotation acceleration during the impulse. This investigation provides basic kinematic information for clinicians to understand the similarities and differences between 2 HVLA side-lying manipulations in the lumbar spine. Use of these findings and novel technology can drive future research initiatives that can both affect clinical decision making and influence teaching environments surrounding spinal manipulative therapy skill acquisition. Copyright © 2017. Published by Elsevier Inc.

Perspectives on stimulating industrial research and development for neglected infectious diseases.

PubMed Central

Webber, D.; Kremer, M.

2001-01-01

This paper summarizes recent thinking on stimulating industrial research and development (R&D) for neglected infectious diseases and argues that it is critical to enlarge the value of the market for medicines and vaccines through, for example, global purchase funds. The most important economic barriers to R&D are that the commercial markets are small and that individual purchasing power is severely limited, even though the number of patients may be very large. Since R&D costs for all diseases are high, this means that returns will not cover investments. Various mechanisms have been proposed to address this economic imbalance (accepting that other barriers will also need to be considered). Economic devices which reduce the costs of R&D--push factors--are useful, but our review suggests that high costs do not explain the shortfall in R&D. Economic devices which address the lack of viable markets have been termed pull factors and are designed to create or secure a market, thereby improving the likelihood of a return on investments. One pull mechanism is the commitment in advance to purchase a product that meets specified criteria, if invented. The purchase-precommitment approach has a number of attractive features. For example, it only rewards successful outputs rather than supporting research that may not succeed. Pull programmes effectively mimic the market and lead companies to favour lines of attack that they believe will lead to marketable products. Overall, a combination of push and pull mechanisms is likely to represent an attractive approach. This could combine, for example, increased funding for public laboratories, public-private partnerships in R&D, purchases of underutilized existing products, and a precommitment to purchase new drugs and vaccines when developed. PMID:11545330

A comparison of lateral ankle ligament suture anchor strength.

PubMed

Barber, F Alan; Herbert, Morley A; Crates, John M

2013-06-01

Lateral ankle ligament repairs increasingly use suture anchors instead of bone tunnels. Our purpose was to compare the biomechanical properties of a knotted and knotless suture anchor appropriate for a lateral ankle ligament reconstruction. In porcine distal fibulae, 10 samples of 2 different PEEK anchors were inserted. The attached sutures were cyclically loaded between 10N and 60N for 200 cycles. A destructive pull was performed and failure loads, cyclic displacement, stiffness, and failure mode recorded. PushLock 2.5 anchors failed before 200 cycles. PushLock 100 cycle displacement was less than Morphix 2.5 displacement (p<0.001). Ultimate failure load for anchors completing 200 cycles was 86.5N (PushLock) and 252.1N (Morphix) (p<0.05). The failure mode was suture breaking for all PushLocks while the Morphix failed equally by anchor breaking and suture breakage. The knotted Morphix demonstrated more displacement and greater failure strength than the knotless PushLock. The PushLock failed consistently with suture breaking. The Morphix anchor failed both by anchor breaking and by suture breaking. Copyright © 2012 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved.

29 CFR 1926.1053 - Ladders.

Code of Federal Regulations, 2010 CFR

2010-07-01

... spreader or locking device shall be provided on each stepladder to hold the front and back sections in an... ascend or descend without continually having to hold, push or pull any part of the device, leaving both... degrees from the horizontal, as measured to the back side of the ladder. (6) Ladders shall be used only on...

14 CFR 27.685 - Control system details.

Code of Federal Regulations, 2012 CFR

2012-01-01

... material used as a bearing: (1) 3.33 for push-pull systems other than ball and roller bearing systems. (2... must be means to prevent the slapping of cables or tubes against other parts. (d) Cable systems must be designed as follows: (1) Cables, cable fittings, turnbuckles, splices, and pulleys must be of an acceptable...

14 CFR 27.685 - Control system details.

Code of Federal Regulations, 2014 CFR

2014-01-01

... material used as a bearing: (1) 3.33 for push-pull systems other than ball and roller bearing systems. (2... must be means to prevent the slapping of cables or tubes against other parts. (d) Cable systems must be designed as follows: (1) Cables, cable fittings, turnbuckles, splices, and pulleys must be of an acceptable...

14 CFR 27.685 - Control system details.

Code of Federal Regulations, 2011 CFR

2011-01-01

... material used as a bearing: (1) 3.33 for push-pull systems other than ball and roller bearing systems. (2... must be means to prevent the slapping of cables or tubes against other parts. (d) Cable systems must be designed as follows: (1) Cables, cable fittings, turnbuckles, splices, and pulleys must be of an acceptable...

14 CFR 29.685 - Control system details.

Code of Federal Regulations, 2012 CFR

2012-01-01

... ultimate bearing strength of the softest material used as a bearing: (1) 3.33 for push-pull systems other... must be means to prevent the slapping of cables or tubes against other parts. (d) Cable systems must be designed as follows: (1) Cables, cable fittings, turnbuckles, splices, and pulleys must be of an acceptable...

14 CFR 29.685 - Control system details.

Code of Federal Regulations, 2011 CFR

2011-01-01

... ultimate bearing strength of the softest material used as a bearing: (1) 3.33 for push-pull systems other... must be means to prevent the slapping of cables or tubes against other parts. (d) Cable systems must be designed as follows: (1) Cables, cable fittings, turnbuckles, splices, and pulleys must be of an acceptable...

14 CFR 29.685 - Control system details.

Code of Federal Regulations, 2014 CFR

2014-01-01

... ultimate bearing strength of the softest material used as a bearing: (1) 3.33 for push-pull systems other... must be means to prevent the slapping of cables or tubes against other parts. (d) Cable systems must be designed as follows: (1) Cables, cable fittings, turnbuckles, splices, and pulleys must be of an acceptable...

Direct sampling for stand density index

Treesearch

Mark J. Ducey; Harry T. Valentine

2008-01-01

A direct method of estimating stand density index in the field, without complex calculations, would be useful in a variety of silvicultural situations. We present just such a method. The approach uses an ordinary prism or other angle gauge, but it involves deliberately "pushing the point" or, in some cases, "pulling the point." This adjusts the...

Women "Opting out" of Academia: At What Cost?

ERIC Educational Resources Information Center

Schneider, Beth Z.; Carden, William; Francisco, Alyson; Jones, Thomas O., Jr.

2011-01-01

Previous research has examined the phenomenon of women "opting out" of the corporate environment. Much of this research has examined both "pull" factors--those of home and family life, and "push" factors--those within the organization which create a competitive environment where women feel they cannot achieve the same measure of success as their…

A Commentary on "Piercing the Bubble": Should Management Education "Confront" Poverty?

ERIC Educational Resources Information Center

Dart, Raymond

2008-01-01

This commentary contrasts "Piercing the Bubble" by proposing "pull" (rather than "push") strategies as a way for business schools to more meaningfully engage poverty and social exclusion. By reframing poverty issues in such a manner that they connect with core business student interests of career opportunities, current management practices, and…

Korean-Chinese Parents' Language Attitudes and Additive Bilingual Education in China

ERIC Educational Resources Information Center

Gao, Fang; Park, Jae

2012-01-01

China's diversity of minority groups, marked by many languages and cultures, has led to much push and pull experience between homogenising forces and indigenous cultures. This is apparent in its bilingual education programme for ethnic minorities, among which Korean diaspora communities are to be counted. Korean-Chinese people in China have been…

Circulating East to East: Understanding the Push-Pull Factors of Chinese Students Studying in Korea

ERIC Educational Resources Information Center

Lee, Se Woong

2017-01-01

Every year, substantial numbers of students choose to study abroad, and China is one of the largest exporters of international students. Interestingly, instead of choosing English-speaking countries, increasingly more Chinese students are choosing nearby Asian countries as their destination to study abroad, particularly Korea. Despite this…

Stop/Start: Overview

Science.gov Websites

/Start technology conserves energy by shutting off the gasoline engine when the vehicle is at rest, such as at a traffic light, and automatically re-starting it when the driver pushes the gas pedal to go engine when pulling out from a stop and generating electricity which is stored in the battery. Main stage

Orthodontic treatment of a stubborn palatally ectopic canine: a case report.

PubMed

Al-Musfir, Tumadher M; Morris, David O

2014-03-01

This is a case report that highlights a different treatment approach in dealing with palatally ectopic canines. The modified transpalatal arch with an 'active' arm was used to align a palatally ectopic canine with 'push' mechanics after the initial use of more conventional 'pull' mechanics (piggy-back archwire technique) had failed.

Korean Sojourners in the Deep South: The Push/Pull Dynamics of Immigration

ERIC Educational Resources Information Center

Lynn, C. Allen; Lee, Sun-A.

2013-01-01

Asians are now the fastest growing ethnic group in the United States. And although disproportionately more likely to live in Western states, some are settling in nontraditional host communities. Focusing on one such instance in southeast Georgia, the present ethnographic case study considers a poultry processing plant's decision to recruit dozens…

Understanding the Programmatic and Contextual Forces That Influence Participation in a Government-Sponsored International Student-Mobility Program

ERIC Educational Resources Information Center

Perna, Laura W.; Orosz, Kata; Jumakulov, Zakir; Kishkentayeva, Marina; Ashirbekov, Adil

2015-01-01

Although prior research establishes the forces that "push" and "pull" students to participate in foreign study, the transferability of findings from earlier studies is limited by the absence of theoretical grounding. In addition, relatively little is known about how a government-sponsored student mobility program promotes…

The Rest of the Story: A Qualitative Study of Chinese and Indian Women's Graduate Education Migration

ERIC Educational Resources Information Center

Yakaboski, Tamara

2013-01-01

Previous migration discourse views educational migration through narrowly defined push-pull forces, which ignores overseas graduate education as a path for maneuvering through restrictive gendered and cultural experiences. The purpose of this exploratory research is to expand migration research and view women's migration decisions as employing…

29 CFR 1918.52 - Specific requirements.

Code of Federal Regulations, 2011 CFR

2011-07-01

... to join sections of, preventer guys. (b) Stoppers. (1) Chain topping lift stoppers shall be in good... chain. (2) Chain stoppers shall be shackled or otherwise secured so that their links are not bent by... control lever is pulled back and lowers when the lever is pushed forward. (d) Heel blocks. (1) When an...

29 CFR 1918.52 - Specific requirements.

Code of Federal Regulations, 2014 CFR

2014-07-01

... to join sections of, preventer guys. (b) Stoppers. (1) Chain topping lift stoppers shall be in good... chain. (2) Chain stoppers shall be shackled or otherwise secured so that their links are not bent by... control lever is pulled back and lowers when the lever is pushed forward. (d) Heel blocks. (1) When an...

29 CFR 1918.52 - Specific requirements.

Code of Federal Regulations, 2010 CFR

2010-07-01

... to join sections of, preventer guys. (b) Stoppers. (1) Chain topping lift stoppers shall be in good... chain. (2) Chain stoppers shall be shackled or otherwise secured so that their links are not bent by... control lever is pulled back and lowers when the lever is pushed forward. (d) Heel blocks. (1) When an...

29 CFR 1918.52 - Specific requirements.

Code of Federal Regulations, 2013 CFR

2013-07-01

... to join sections of, preventer guys. (b) Stoppers. (1) Chain topping lift stoppers shall be in good... chain. (2) Chain stoppers shall be shackled or otherwise secured so that their links are not bent by... control lever is pulled back and lowers when the lever is pushed forward. (d) Heel blocks. (1) When an...

29 CFR 1918.52 - Specific requirements.

Code of Federal Regulations, 2012 CFR

2012-07-01

... to join sections of, preventer guys. (b) Stoppers. (1) Chain topping lift stoppers shall be in good... chain. (2) Chain stoppers shall be shackled or otherwise secured so that their links are not bent by... control lever is pulled back and lowers when the lever is pushed forward. (d) Heel blocks. (1) When an...

Push and Pull in the Classroom: Competition, Gender and the Neoliberal Subject

ERIC Educational Resources Information Center

Wilkins, Andrew

2012-01-01

In this paper I explore how learning strategies based on competition and zero-sum thinking are inscribed into the dynamics of classroom interaction shaping relations between high-achieving pupils, and link elements of these practices to market trends in British education policy discourse. A detour through the politico-historical negotiations…

Use of the chop hook to stabilize the capsular bag in patients with crystalline lens dislocations and cataracts.

PubMed

Zeng, Yanfeng; Fan, Licheng; Lu, Peirong

2017-04-01

Objective To observe the treatment effects of chop hook-assisted phacoemulsification surgery in patients with crystalline lens dislocation. Methods Thirty-seven eyes with cataracts and crystalline lens dislocations underwent cataract surgery. An L-shaped chop hook was introduced into the anterior chamber, and the tip was pushed or pulled to the centre of the anterior capsular edge of the zonular dialysis during the cataract operation. Postoperative follow-up was conducted for ≥ 1 month. Results All patients' postoperative visual abilities improved except one patient with glaucoma. One patient who underwent -5D intraocular lens implantation exhibited vision of 1/50. Visual acuity was less than 6/20 in 6 eyes, 6/20 to 10/20 in 7 eyes, and greater than 10/20 in 22 eyes. Conclusions L-shaped chop hooks can be used to push or pull the anterior capsular edge of the zonular dialysis for protection and avoidance of further zonular damage. This strategy provides satisfactory effects and reduces use of additional instruments.

Microchemical Pen: An Open Microreactor for Region-Selective Surface Modification.

PubMed

Mao, Sifeng; Sato, Chiho; Suzuki, Yuma; Yang, Jianmin; Zeng, Hulie; Nakajima, Hizuru; Yang, Ming; Lin, Jin-Ming; Uchiyama, Katsumi

2016-10-18

Various micro surface-modification approaches including photolithography, dip-pen lithography and ink-jet systems have been developed and used to extend the functionalities of solid surfaces. While those approaches work in the "open space", push-pull systems which work in solutions have recently drawn considerable attention. However, the confining flows performed by push-pull systems have realized only the dispense process, while microscale, region-selective chemical reactions have remained unattainable. This study reports a microchemical pen that enables region-selective chemical reactions for the micro surface modification/patterning. The chemical pen is based on the principle of microfluidic laminar flows and the resulting mixing of reagents by the mutual diffusion. The tiny diffusion layer performs as the working region. This report represents the first demonstration of an open microreactor in which two different reagents react on a real solid sample. The multifunctional characteristics of the microchemical pen are confirmed by different types of reactions in many research areas, including inorganic chemistry, polymer science, electrochemistry and biological sample treatment. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Comparison of Aedes aegypti (Diptera: Culicidae) resting behavior on two fabric types under consideration for insecticide treatment in a push-pull strategy.

PubMed

Tainchum, Krajana; Polsomboon, Suppaluck; Grieco, John P; Suwonkerd, Wannapa; Prabaripai, Atchariya; Sungvornyothin, Sungsit; Chareonviriyaphap, Theeraphap; Achee, Nicole L

2013-01-01

Aedes aegypti (L.), the primary vector of dengue and dengue hemorrhagic fever, breeds and rests predominately inside human dwellings. With no current vaccine available, vector control remains the mainstay for dengue management and novel approaches continue to be needed to reduce virus transmission. This requires a full understanding of Ae. aegypti ecology to design effective strategies. One novel approach is the use of contact irritants at target resting sites inside homes to make the surface unacceptable and cause vectors to escape before biting. The objective of the current study was to observe indoor resting behavior patterns of female Ae. aegypti within experimental huts in response to two fabrics under consideration for insecticide treatment: cotton and polyester. Results indicate that fabric type, coverage ratio of dark to light fabric and placement configuration (vertical vs. horizontal) all influenced the resting pattern of mosquito cohorts. Findings from this study will guide evaluations of a push-pull strategy designed to exploit contact irritant behaviors and drive Ae. aegypti out of homes prefeeding.

The Determination of Production and Distribution Policy in Push-Pull Production Chain with Supply Hub as the Junction Point

NASA Astrophysics Data System (ADS)

Sinaga, A. T.; Wangsaputra, R.

2018-03-01

The development of technology causes the needs of products and services become increasingly complex, diverse, and fluctuating. This causes the level of inter-company dependencies within a production chains increased. To be able to compete, efficiency improvements need to be done collaboratively in the production chain network. One of the efforts to increase efficiency is to harmonize production and distribution activities in the production chain network. This paper describes the harmonization of production and distribution activities by applying the use of push-pull system and supply hub in the production chain between two companies. The research methodology begins with conducting empirical and literature studies, formulating research questions, developing mathematical models, conducting trials and analyses, and taking conclusions. The relationship between the two companies is described in the MINLP mathematical model with the total cost of production chain as the objective function. Decisions generated by the mathematical models are the size of production lot, size of delivery lot, number of kanban, frequency of delivery, and the number of understock and overstock lot.

Shoulder joint loading and posture during medicine cart pushing task.

PubMed

Xu, Xu; Lin, Jia-Hua; Boyer, Jon

2013-01-01

Excessive physical loads and awkward shoulder postures during pushing and pulling are risk factors for shoulder pain. Pushing a medicine cart is a major component of a work shift for nurses and medical assistants in hospitals and other health care facilities. A laboratory experiment was conducted to examine the effects of common factors (e.g., lane congestion, cart load stability, floor surface friction) on shoulder joint moment and shoulder elevation angle of participants during cart pushing. Participants pushed a medicine cart on straight tracks and turning around right-angle corners. Peak shoulder joint moments reached 25.1 Nm, 20.3 Nm, and 26.8 Nm for initial, transition, and turning phases of the pushing tasks, indicating that shoulder joint loading while pushing a medical cart is comparable to levels previously reported from heavy manual activities encountered in industry (e.g., garbage collection). Also, except for user experience, all other main study factors, including congestion level, cart load stability, location of transition strip, shoulder tendency, surface friction, and handedness, significantly influenced shoulder joint moment and shoulder elevation angle. The findings provide a better understanding of shoulder exposures associated with medicine cart operations and may be helpful in designing and optimizing the physical environment where medicine carts are used.

Kinematics and kinetics of the bench-press and bench-pull exercises in a strength-trained sporting population.

PubMed

Pearson, Simon N; Cronin, John B; Hume, Patria A; Slyfield, David

2009-09-01

Understanding how loading affects power production in resistance training is a key step in identifying the most optimal way of training muscular power - an essential trait in most sporting movements. Twelve elite male sailors with extensive strength-training experience participated in a comparison of kinematics and kinetics from the upper body musculature, with upper body push (bench press) and pull (bench pull) movements performed across loads of 10-100% of one repetition maximum (1RM). 1RM strength and force were shown to be greater in the bench press, while velocity and power outputs were greater for the bench pull across the range of loads. While power output was at a similar level for the two movements at a low load (10% 1RM), significantly greater power outputs were observed for the bench pull in comparison to the bench press with increased load. Power output (Pmax) was maximized at higher relative loads for both mean and peak power in the bench pull (78.6 +/- 5.7% and 70.4 +/- 5.4% of 1RM) compared to the bench press (53.3 +/- 1.7% and 49.7 +/- 4.4% of 1RM). Findings can most likely be attributed to differences in muscle architecture, which may have training implications for these muscles.

On Heels and Toes: How Ants Climb with Adhesive Pads and Tarsal Friction Hair Arrays

PubMed Central

Endlein, Thomas; Federle, Walter

2015-01-01

Ants are able to climb effortlessly on vertical and inverted smooth surfaces. When climbing, their feet touch the substrate not only with their pretarsal adhesive pads but also with dense arrays of fine hairs on the ventral side of the 3rd and 4th tarsal segments. To understand what role these different attachment structures play during locomotion, we analysed leg kinematics and recorded single-leg ground reaction forces in Weaver ants (Oecophylla smaragdina) climbing vertically on a smooth glass substrate. We found that the ants engaged different attachment structures depending on whether their feet were above or below their Centre of Mass (CoM). Legs above the CoM pulled and engaged the arolia (‘toes’), whereas legs below the CoM pushed with the 3rd and 4th tarsomeres (‘heels’) in surface contact. Legs above the CoM carried a significantly larger proportion of the body weight than legs below the CoM. Force measurements on individual ant tarsi showed that friction increased with normal load as a result of the bending and increasing side contact of the tarsal hairs. On a rough sandpaper substrate, the tarsal hairs generated higher friction forces in the pushing than in the pulling direction, whereas the reverse effect was found on the smooth substrate. When the tarsal hairs were pushed, buckling was observed for forces exceeding the shear forces found in climbing ants. Adhesion forces were small but not negligible, and higher on the smooth substrate. Our results indicate that the dense tarsal hair arrays produce friction forces when pressed against the substrate, and help the ants to push outwards during horizontal and vertical walking. PMID:26559941

On Heels and Toes: How Ants Climb with Adhesive Pads and Tarsal Friction Hair Arrays.

PubMed

Endlein, Thomas; Federle, Walter

2015-01-01

Ants are able to climb effortlessly on vertical and inverted smooth surfaces. When climbing, their feet touch the substrate not only with their pretarsal adhesive pads but also with dense arrays of fine hairs on the ventral side of the 3rd and 4th tarsal segments. To understand what role these different attachment structures play during locomotion, we analysed leg kinematics and recorded single-leg ground reaction forces in Weaver ants (Oecophylla smaragdina) climbing vertically on a smooth glass substrate. We found that the ants engaged different attachment structures depending on whether their feet were above or below their Centre of Mass (CoM). Legs above the CoM pulled and engaged the arolia ('toes'), whereas legs below the CoM pushed with the 3rd and 4th tarsomeres ('heels') in surface contact. Legs above the CoM carried a significantly larger proportion of the body weight than legs below the CoM. Force measurements on individual ant tarsi showed that friction increased with normal load as a result of the bending and increasing side contact of the tarsal hairs. On a rough sandpaper substrate, the tarsal hairs generated higher friction forces in the pushing than in the pulling direction, whereas the reverse effect was found on the smooth substrate. When the tarsal hairs were pushed, buckling was observed for forces exceeding the shear forces found in climbing ants. Adhesion forces were small but not negligible, and higher on the smooth substrate. Our results indicate that the dense tarsal hair arrays produce friction forces when pressed against the substrate, and help the ants to push outwards during horizontal and vertical walking.

Friction pull plug welding: dual chamfered plate hole

NASA Technical Reports Server (NTRS)

Coletta, Edmond R. (Inventor); Cantrell, Mark A. (Inventor)

2001-01-01

Friction Pull Plug Welding (FPPW) is a solid state repair process for defects up to one inch in length, only requiring single sided tooling (OSL) for usage on flight hardware. Early attempts with FPPW followed the matching plug/plate geometry precedence of the successful Friction Push Plug Welding program, however no defect free welds were achieved due to substantial plug necking and plug rotational stalling. The dual chamfered hole has eliminated plug rotational stalling, both upon initial plug/plate contact and during welding. Also, the necking of the heated plug metal under a tensile heating/forging load has been eliminated through the usage of the dual chamfered plate hole.

Climate change education in informal settings: Using boundary objects to frame network dissemination

NASA Astrophysics Data System (ADS)

Steiner, Mary Ann

This study of climate change education dissemination takes place in the context of a larger project where institutions in four cities worked together to develop a linked set of informal learning experiences about climate change. Each city developed an organizational network to explore new ways to connect urban audiences with climate change education. The four city-specific networks shared tools, resources, and knowledge with each other. The networks were related in mission and goals, but were structured and functioned differently depending on the city context. This study illustrates how the tools, resources, and knowledge developed in one network were shared with networks in two additional cities. Boundary crossing theory frames the study to describe the role of objects and processes in sharing between networks. Findings suggest that the goals, capacity and composition of networks resulted in a different emphasis in dissemination efforts, in one case to push the approach out to partners for their own work and in the other to pull partners into a more collaborative stance. Learning experiences developed in each city as a result of the dissemination reflected these differences in the city-specific emphasis with the push city diving into messy examples of the approach to make their own examples, and the pull city offering polished experiences to partners in order to build confidence in the climate change messaging. The networks themselves underwent different kinds of growth and change as a result of dissemination. The emphasis on push and use of messy examples resulted in active use of the principles of the approach and the pull emphasis with polished examples resulted in the cultivation of partnerships with the hub and the potential to engage in the educational approach. These findings have implications for boundary object theory as a useful grounding for dissemination designs in the context of networks of informal learning organizations to support a shift in communication approach, particularly when developing interventions for wicked socio-scientific issues such as climate change.

Rapid spread of complex change: a case study in inpatient palliative care.

PubMed

Della Penna, Richard; Martel, Helene; Neuwirth, Esther B; Rice, Jennifer; Filipski, Marta I; Green, Jennifer; Bellows, Jim

2009-12-29

Based on positive findings from a randomized controlled trial, Kaiser Permanente's national executive leadership group set an expectation that all Kaiser Permanente and partner hospitals would implement a consultative model of interdisciplinary, inpatient-based palliative care (IPC). Within one year, the number of IPC consultations program-wide increased almost tenfold from baseline, and the number of teams nearly doubled. We report here results from a qualitative evaluation of the IPC initiative after a year of implementation; our purpose was to understand factors supporting or impeding the rapid and consistent spread of a complex program. Quality improvement study using a case study design and qualitative analysis of in-depth semi-structured interviews with 36 national, regional, and local leaders. Compelling evidence of impacts on patient satisfaction and quality of care generated 'pull' among adopters, expressed as a remarkably high degree of conviction about the value of the model. Broad leadership agreement gave rise to sponsorship and support that permeated the organization. A robust social network promoted knowledge exchange and built on an existing network with a strong interest in palliative care. Resource constraints, pre-existing programs of a different model, and ambiguous accountability for implementation impeded spread. A complex, hospital-based, interdisciplinary intervention in a large health care organization spread rapidly due to a synergy between organizational 'push' strategies and grassroots-level pull. The combination of push and pull may be especially important when the organizational context or the practice to be spread is complex.

The NASA technology push towards future space mission systems

NASA Technical Reports Server (NTRS)

Sadin, Stanley R.; Povinelli, Frederick P.; Rosen, Robert

1988-01-01

As a result of the new Space Policy, the NASA technology program has been called upon to a provide a solid base of national capabilities and talent to serve NASA's civil space program, commercial, and other space sector interests. This paper describes the new technology program structure and its characteristics, traces its origin and evolution, and projects the likely near- and far-term strategic steps. It addresses the alternative 'push-pull' approaches to technology development, the readiness levels to which the technology needs to be developed for effective technology transfer, and the focused technology programs currently being implemented to satisfy the needs of future space systems.

When push comes to shove: sites of vulnerability, personal transformation, and trafficked women's migration decisions.

PubMed

Yea, Sallie

2005-01-01

Discussions of the push and pull factors behind trafficked women's decisions to migrate abroad for tenuous work opportunities in the "entertainment" sector tend to variously privilege poverty, familial obligations, and, more recently, personal opportunism. This reinforces more general observations about motivations for "Third World" women who migrate to more developed regions globally. Although these factors are indeed important, the author's research has revealed the relevance of other explanations for migration decisions, including the prevalence of domestic violence, family dissolution, and escape from personal circumstances, which are themselves products of low self-esteem and sense of self-worth.

Ion Beam Deflection (AKA Push-Me/Pull-You)

NASA Technical Reports Server (NTRS)

Brophy, John

2013-01-01

The Ion Beam Deflection provides the following potential advantages over other asteroid deflection systems. Like the gravity tractor, it doesn't require despinning of the asteroid. Unlike the gravity tractor, it provides a significantly higher coupling force that is independent of the asteroid size. The concept could be tested as part of the baseline Asteroid Redirect Robotic Mission. The thrust and total impulse are entirely within the design of the SEP vehicle. The total impulse is potentially competitive with kinetic impactors and eliminates the need for a second rendezvous spacecraft.?Gridded ion thrusters provide beam divergence angles of a few degrees enabling long stand-off distances from the asteroid. Mitigating control issues. Minimizing back-sputter contamination risks

Uptake of cystic fibrosis testing in primary care: supply push or demand pull?

PubMed Central

Bekker, H; Modell, M; Denniss, G; Silver, A; Mathew, C; Bobrow, M; Marteau, T

1993-01-01

OBJECTIVE--To determine the acceptability and feasibility of screening for carriers of cystic fibrosis in a primary care setting. DESIGN--Follow up study over 15 months of patients offered carrier testing by mouthwash. SETTING--A general practice in inner London. SUBJECTS--5529 patients aged 18-45 invited by various methods and combinations of methods (letter, booklet, personal approach) for testing. MAIN OUTCOME MEASURES--Uptake of screening, anxiety, and knowledge of test. RESULTS--957 (17%) invitees were screened over the 15 months. 28 carriers and no carrier couples were detected. Uptake rates were 12% (59/502 patients) among patients invited by letter and tested by appointment; 9% (47/496) among patients invited by letter, with leaflet, and tested by appointment; 4% (128/2953) among patients invited by letter six weeks before the end of the study and tested by appointment; 17% (81/471) among patients offered passive opportunistic testing; 70% (453/649) among patients offered active opportunistic testing; and 25% (22/88) among patients offered active opportunistic testing by appointment. A short term rise in anxiety among those given a positive test result had dissipated by three months. At three months about one fifth and one third of those given positive and negative results respectively did not understand their results correctly. CONCLUSION--These results suggest that the strongest variable in determining uptake of screening is the active approach by a health professional offering immediate testing. It remains to be resolved whether the high uptake rates achieved by active recruitment indicate a supply push for this new test rather than a demand from the population. PMID:8329922

Self-Reinforcing Spatial Clusters of Migration and Socio-Economic Conditions in Finland in 1998-2006

ERIC Educational Resources Information Center

Lehtonen, Olli; Tykkylainen, Markku

2010-01-01

All the time the long economic growth period of 1992-2008 prevailed in Finland, the economic landscape was changing constantly and markedly. We analyse in this article how net migration plagued certain less competitive, mainly rural push-lose municipalities, and boosted in-migration to the pull-win municipalities in metropolitan environments…

How Does a Hopping Kangaroo Breathe?

ERIC Educational Resources Information Center

Giuliodori, Mauricio J.; Lujan, Heidi L.; Janbaih, Hussein; DiCarlo, Stephen E.

2010-01-01

We developed a model to demonstrate how a hopping kangaroo breathes. Interestingly, a kangaroo uses less energy to breathe while hopping than while standing still. This occurs, in part, because rather than using muscle power to move air into and out of the lungs, air is pulled into (inspiration) and pushed out of (expiration) the lungs as the…

Global Argonauts: Returnees and Diaspora as Sources of Innovation in China and Israel

ERIC Educational Resources Information Center

Welch, Anthony; Hao, Jie

2016-01-01

The paper focuses on returnees and knowledge diaspora as important sources for human resources development, identifying push and pull factors that also contribute significantly to innovation. For both China and Israel, their high-skilled diaspora are a major policy priority: each has a substantial, high-skilled diaspora and policies and programmes…

The Prerequisites to Ukrainian Students Participation in Study Abroad Programs at the Canadian Universities and Colleges

ERIC Educational Resources Information Center

Zhukovskyi, Vasyl; Simak, Kateryna

2015-01-01

The problem of outbound mobility of Ukrainian students has been presented in the paper. The data regarding the number of Ukrainian students studying in Canada has been pointed out. This paper examines "push-pull" factors which motivate Ukrainian students to seek higher education overseas and factors which attract Ukrainian students to…

Inexpensive high vacuum feedthroughs.

NASA Technical Reports Server (NTRS)

Gerber, S.; Post, D.

1973-01-01

Description of the use of rigid coaxial cable in the construction of high vacuum coaxial and coaxial push-pull rotary motion feedthroughs. This type of feedthroughs is shown to be extremely cheap and simple to make and modify. It can be used for moderately high voltages and provides a continuous, well shielded, low-noise feedthrough cable in any desired configuration.

At the Crossroads of Access and Financial Stability: The Push and Pull on the Enrollment Manager

ERIC Educational Resources Information Center

Humphrey, Keith B.

2006-01-01

This study contributes to the developing literature on enrollment management by looking at how individual enrollment management organizations interact within the changing higher education landscape. One way to understand how an organization interacts is to understand its leader. Thus, this study focuses on the leaders of enrollment management as a…

Intelligence after Intellipedia: Improving the Push Pull Balance with a Social Networking Utility

DTIC Science & Technology

2010-02-08

School of Information and Library Science Approved for public release; distribution is...PERFORMING ORGANIZATION REPORT NUMBER School of Information and Library Science 9. SPONSORING...892‐4706 
 School
Affiliation:
 
 Pratt
Institute School
of
Information
&
 Library 
 Science 144
West
Fourteenth
Street New
York,
NY
10013

Defense Technical Information Center’s 2010 Student Paper Competition: The Winning Papers

DTIC Science & Technology

2010-05-05

Information and Library Science ; Intelligence after Intellipedia: Improving the Push Pull Balance with a Social Networking Utility, by Ariane Ben Eli and...Jeremy Hutchins, Pratt Institute, School of Information and Library Science ; and Information Needs and Behaviors -- NASA Science Program Executives, by Shannon Lantzy, University of Maryland, College of Information Studies.

Compensatory Education Product Evaluation: Elementary and Secondary Programs 1991-1992.

ERIC Educational Resources Information Center

Saginaw Public Schools, MI. Dept. of Evaluation Services.

An evaluation was done of compensatory educational programs in reading and mathematics in the Saginaw (Michigan) School District. The elementary Compensatory Education (CE) program is both a push-in format (grades 1 and 2) and a pull-out format (periodically taking students out of regular classrooms) that serves 2,045 students in grades 1 through…

Between the Cultural Push and Cultural Pull: An Exploration of Chinese International Students' Self-Concept

ERIC Educational Resources Information Center

Song, Lei

2014-01-01

The purpose of this study is to investigate perceived changes in self-concept among Chinese international students in the United States. Because a huge cultural distance exists between China and the U.S. in terms of schooling systems, higher education traditions, and practices, Chinese international students need both linguistic and cultural…

Behavior and Development: Physical Development--"Riding Along" Outdoors!

ERIC Educational Resources Information Center

Strickland, Eric

2005-01-01

Riding toys and push-pull toys are traditionally part of every early childhood program. Young children can develop a wide variety of skills and get numerous health benefits from riding toys if one is careful and thoughtful in setting up the riding-toy area. This article describes various types of riding toys and activity ideas to enhance…

Using the Git Software Tool on the Peregrine System | High-Performance

Science.gov Websites

branch workflow. Create a local branch called "experimental" based on the current master... git branch experimental Use your branch (start working on that experimental branch....) git checkout experimental git pull origin experimental # work, work, work, commit.... Send local branch to the repo git push

Adjusting Curvatures Of Large Mirrors And Lenses

NASA Technical Reports Server (NTRS)

Birnbaum, Morris M.

1992-01-01

Actuators apply stresses to generate distortions counteracting undesired distortions in technique for adjusting curvature of large focusing mirror or lens. Motor-and-gear assemblies under remote control vary squeeze of ring clamp and push or pull of hollow shaft to make fine adjustments in curvature of mirror. Applicable to large astronomical-telescope mirrors with diameters of 60 cm or more.

Push and Pull Factors Determine Adolescents' Intentions of Participation in Nature Observation: Reconnecting Local Students with Nature in China

ERIC Educational Resources Information Center

Zhang, Weizhe; Williams, Sophie J.; Wang, Ximin; Chen, Jin

2017-01-01

Nature experiences are essential for fostering pro-environmental behavior. In this study, a wildlife observation toolbox was provided to students to encourage participation in nature observation clubs. A total of 340 adolescents joined the clubs. We identified the determinants of participation intentions with a mixed approach combing…

¿Y Los De Teatro Cuándo Vuelven? The Future of Internationalised Applied Theatre in Nicaragua

ERIC Educational Resources Information Center

Sadeghi-Yekta, Kirsten

2017-01-01

This article looks at the concept of "internationalised applied theatre" within Nicaraguan non-profit arts organisation Movimiento Teatro Popular Sin Fronteras (Movitep-SF). It examines the push-and-pull factors between local sovereignties and the international aid industry, and shows how this interaction occurs on a micro-level between…

A Quilt of Many Colors

ERIC Educational Resources Information Center

Masse, Don

2012-01-01

The author discovered artist Eleanor McCain's work on "Dear Ada," an art blog he follows. McCain makes brightly colored art quilts using various rectangles and squares. She creates visual "pop" by using these shapes in a variety of sizes and bright colors. There is an interesting spatial "push and pull" that happens when looking at her quilts.…

Examination of Students' Selection Criteria for International Education

ERIC Educational Resources Information Center

Ahmad, Syed Zamberi; Buchanan, F. Robert; Ahmad, Norita

2016-01-01

Purpose: Motivations for study abroad in tourism and hospitality were examined as to the influence of a variety of personal criteria in the individual decision process of adult learners to select a host country and host institution of study. The paper aims to discuss this issue. Design/methodology/approach: Push-pull factors (Mazzarol and Soutar,…

The Suburbanization of America Or the Shrinking of the Cities

ERIC Educational Resources Information Center

Weaver, Robert C.

1977-01-01

Argues that "the social pattern of suburbia, especially its racial exclusion, cannot and will not be altered unless and until we recognize the process and identify the many factors which make up the push and pull in migration. The contemporary suburb is different from its earlier namesake in both function and form." (Author/JM)

The Wonderful World of Worms

ERIC Educational Resources Information Center

Marrero, Meghan E.; Gunning, Amanda M.; Tazi, Zoila

2014-01-01

Kindergarteners have plenty of opportunities to discover and investigate cause and effect in their own lives and in all subject areas. If it rains, they may not be able to go outside for recess. If they pump harder on the swing, the swing will go faster and higher. In science, they may investigate pushes and pulls; discover how exposure to…

Using Social Networks to Enhance Teaching and Learning Experiences in Higher Learning Institutions

ERIC Educational Resources Information Center

Balakrishnan, Vimala

2014-01-01

The paper first explores the factors that affect the use of social networks to enhance teaching and learning experiences among students and lecturers, using structured questionnaires prepared based on the Push-Pull-Mooring framework. A total of 455 students and lecturers from higher learning institutions in Malaysia participated in this study.…

Witnessing the World: The Power of True Global Service

ERIC Educational Resources Information Center

Piccone, Chris

2013-01-01

The school where Chris Piccone teaches eighth-grade English maintains a desire to pull its community from its comfort zones to experience first hand the crushing poverty in the Dominican Republic. Although he always thought of himself as a bleeding heart, who was proud that he pushed his students out of their academic comfort zones, he realized…

Choosing a Higher Education Study Abroad Destination: What Mainland Chinese Parents and Students Rate as Important

ERIC Educational Resources Information Center

Bodycott, Peter

2009-01-01

Mainland China is one of the largest sources of undergraduate and postgraduate students. Previous research has identified the push-pull factors and features that influence a student choice of study abroad destination. This article extends understanding by identifying and examining what 251 mainland Chinese parents and 100 students rated as most…

Social Media and Their Use in Learning: A Comparative Analysis between Australia and Malaysia from the Learners' Perspectives

ERIC Educational Resources Information Center

Balakrishnan, Vimala; Teoh, Kung Keat; Pourshafie, Tahereh; Liew, Teik Kooi

2017-01-01

This study is an investigation into factors that encourage and/or inhibit the use of social media in the academic learning process between Australian and Malaysian students at higher learning institutions. Push-pull-mooring theory was used as a guide, resulting in seven independent variables ("convenience", "social influence",…

Push and Pull: The Influence of Race/Ethnicity on Agency in Doctoral Student Career Advancement

ERIC Educational Resources Information Center

Jaeger, Audrey J.; Mitchall, Allison; O'Meara, KerryAnn; Grantham, Ashley; Zhang, Jingjing; Eliason, Jennifer; Cowdery, Kelly

2017-01-01

This study examined and enriched our understanding of the career choice process for doctoral students of color in science, technology, engineering, and math (STEM) fields. In addition, it explored the challenges facing all doctoral students in STEM in understanding and making meaning of diversity as it relates to individual perspectives and…

Student Destination Choices in Higher Education: Exploring Attitudes of Brazilian Students to Study in the United Kingdom

ERIC Educational Resources Information Center

Foster, Monika

2014-01-01

Cross-border education provides evidence about international student destination choice including the push and pull model of international student choice. The research upon which this article is based, into Brazilian students' decisions to study at universities in the United Kingdom, reveals some particular barriers such as cost, negative past…

Whose Evidence Base? The Dynamic Effects of Ownership, Receptivity and Values on Collaborative Evidence-Informed Policy Making

ERIC Educational Resources Information Center

Shine, Kasey Treadwell; Bartley, Brendan

2011-01-01

This paper explores questions of ownership of and receptivity to research-based evidence and, in combination with often competing values, their effect on collaborative evidence-informed policy making (EIPM). We propose that these issues generate a "dynamo" of push-pull factors for policy makers, researchers and research managers. Through…

Watch 60-Seconds of Major SLS Hardware Being Moved and Put in the Test Stand at NASA Marshall

NASA Image and Video Library

2016-10-13

A test version of the launch vehicle stage adapter (LVSA) for NASA’s new rocket, the Space Launch System, is moved to a 65-foot-tall test stand at the agency’s Marshall Space Flight Center in Huntsville, Alabama. The test version LVSA will be stacked with other test pieces of the upper part of the SLS rocket and pushed, pulled and twisted as part of an upcoming test series to ensure each structure can withstand the incredible stresses of launch. The LVSA joins the core stage simulator, which was loaded into the test stand Sept. 21. The other three qualification articles and the Orion simulator will complete the stack later this fall. SLS will be the world’s most powerful rocket, and with the Orion spacecraft, take astronauts to deep-space destinations, including the Journey to Mars. More information on the upcoming test series can be found here: http://go.nasa.gov/2dS8yXB

SLS Rocket Hardware Moved to NASA Marshall Stand for Upcoming Test Series (30-second timelapse)

NASA Image and Video Library

2016-10-13

A test version of the launch vehicle stage adapter (LVSA) for NASA’s new rocket, the Space Launch System, is moved to a 65-foot-tall test stand at the agency’s Marshall Space Flight Center in Huntsville, Alabama. The test version LVSA will be stacked with other test pieces of the upper part of the SLS rocket and pushed, pulled and twisted as part of an upcoming test series to ensure each structure can withstand the incredible stresses of launch. The LVSA joins the core stage simulator, which was loaded into the test stand Sept. 21. The other three qualification articles and the Orion simulator will complete the stack later this fall. SLS will be the world’s most powerful rocket, and with the Orion spacecraft, take astronauts to deep-space destinations, including the Journey to Mars. More information on the upcoming test series can be found here: http://go.nasa.gov/2dS8yXB

Changeability of tissue's magnetic remanence after galvanic-magnetostimulation in upper-back pain treatment.

PubMed

Dyszkiewicz, Andrzej Jan; Kępiński, Paweł; Połeć, Paweł; Chachulski, Damian; Nowak-Kostrzewska, Ewa

2015-11-01

Research was conducted on parametric profiles of healthy subjects and patients with cervico-brachial pain syndrome resulting from C4/5 and/or C5/6 discopathy, including magnetic remanence of tissues in marker points 1-12 (L+R) and functional parameters, and their subsequent change after treatment in group A, using method of push-pull galvanic magnetostimulation (GMT 2.0). GMT 2.0 device, comprised of one air solenoid and three galvanic solenoids in electrolytic tubs, was designed for push-pull magnetostimulation of the head, coupled with simultaneous stimulation of the limbs. Clinical trial was conducted in Outpatient Private Clinic "VIS" under the auspices of Silesian Higher Medical School in Katowice, Poland. 55 subjects participated in the study: control group K consisted of 23 healthy individuals, whereas 33 patients in group A were treated using GMT 2.0. Only patients in group A were treated with GMT 2.0 during 40-min sessions over a period of 10 days. Parametric profile of the patients was defined using various measurements: electronic SFTR test (C-Th-shoulders), HR, RR, BDI and VAS tests, magnetic remanence in marker points 1-12 (L+R) and blood parameters: HB, ER, CREA, BIL, K(+), Na(+), Cl(-) Fe(2+), Ca(2+) and Mg(2+). There was a significant reduction in pain (VAS), increase in the range of motion (SFTR), lower depression symptoms (BDI), slower heart rate (HR), lower blood pressure (RR), greater concentration of Mg(2+), K(+), Ca(2+)ions and reduction in the concentration of BIL, CREA Fe(2+) after GMT 2.0 treatment in group A. Evaluation of magnetic remanence in marker points M1-12 (L+R) initially showed higher values in group K, which after treatment were normalized to values similar to those in group K. GMT 2.0 treatment in group A resulted in normalization of magnetic remanence, synergically with increased range of motion (SFTR test), decreased HR and RR parameters, smaller depressive trends (BDI test), as well as increased ion levels (K(+), Mg(2+), Ca(2+)) and better functional parameters of kidneys and liver. Copyright © 2015 Elsevier Ltd. All rights reserved.

Flat-Cladding Fiber Bragg Grating Sensors for Large Strain Amplitude Fatigue Tests

PubMed Central

Feng, Aihen; Chen, Daolun; Li, Cheng; Gu, Xijia

2010-01-01

We have successfully developed a flat-cladding fiber Bragg grating sensor for large cyclic strain amplitude tests of up to ±8,000 με. The increased contact area between the flat-cladding fiber and substrate, together with the application of a new bonding process, has significantly increased the bonding strength. In the push-pull fatigue tests of an aluminum alloy, the plastic strain amplitudes measured by three optical fiber sensors differ only by 0.43% at a cyclic strain amplitude of ±7,000 με and 1.9% at a cyclic strain amplitude of ±8,000 με. We also applied the sensor on an extruded magnesium alloy for evaluating the peculiar asymmetric hysteresis loops. The results obtained were in good agreement with those measured from the extensometer, a further validation of the sensor. PMID:22163621

Micromachined peristaltic pump

NASA Technical Reports Server (NTRS)

Hartley, Frank T. (Inventor)

1998-01-01

A micromachined pump including a channel formed in a semiconductor substrate by conventional processes such as chemical etching. A number of insulating barriers are established in the substrate parallel to one another and transverse to the channel. The barriers separate a series of electrically conductive strips. An overlying flexible conductive membrane is applied over the channel and conductive strips with an insulating layer separating the conductive strips from the conductive membrane. Application of a sequential voltage to the series of strips pulls the membrane into the channel portion of each successive strip to achieve a pumping action. A particularly desirable arrangement employs a micromachined push-pull dual channel cavity employing two substrates with a single membrane sandwiched between them.

Attainment and retention of force moderation following laparoscopic resection training with visual force feedback.

PubMed

Hernandez, Rafael; Onar-Thomas, Arzu; Travascio, Francesco; Asfour, Shihab

2017-11-01

Laparoscopic training with visual force feedback can lead to immediate improvements in force moderation. However, the long-term retention of this kind of learning and its potential decay are yet unclear. A laparoscopic resection task and force sensing apparatus were designed to assess the benefits of visual force feedback training. Twenty-two male university students with no previous experience in laparoscopy underwent relevant FLS proficiency training. Participants were randomly assigned to either a control or treatment group. Both groups trained on the task for 2 weeks as follows: initial baseline, sixteen training trials, and post-test immediately after. The treatment group had visual force feedback during training, whereas the control group did not. Participants then performed four weekly test trials to assess long-term retention of training. Outcomes recorded were maximum pulling and pushing forces, completion time, and rated task difficulty. Extreme maximum pulling force values were tapered throughout both the training and retention periods. Average maximum pushing forces were significantly lowered towards the end of training and during retention period. No significant decay of applied force learning was found during the 4-week retention period. Completion time and rated task difficulty were higher during training, but results indicate that the difference eventually fades during the retention period. Significant differences in aptitude across participants were found. Visual force feedback training improves on certain aspects of force moderation in a laparoscopic resection task. Results suggest that with enough training there is no significant decay of learning within the first month of the retention period. It is essential to account for differences in aptitude between individuals in this type of longitudinal research. This study shows how an inexpensive force measuring system can be used with an FLS Trainer System after some retrofitting. Surgical instructors can develop their own tasks and adjust force feedback levels accordingly.

Pegasus delivers SLS engine section

NASA Image and Video Library

2017-03-03

NASA engineers install test hardware for the agency's new heavy lift rocket, the Space Launch System, into a newly constructed 50-foot structural test stand at NASA's Marshall Space Flight Center. In the stand, hydraulic cylinders will be electronically controlled to push, pull, twist and bend the test article with millions of pounds of force. Engineers will record and analyze over 3,000 channels of data for each test case to verify the capabilities of the engine section and validate that the design and analysis models accurately predict the amount of loads the core stage can withstand during launch and ascent. The engine section, recently delivered via NASA's barge Pegasus from NASA's Michoud Assembly Facility, is the first of four core stage structural test articles scheduled to be delivered to Marshall for testing. The engine section, located at the bottom of SLS's massive core stage, will house the rocket's four RS-25 engines and be an attachment point for the two solid rocket boosters.

Pegasus delivers SLS engine section

NASA Image and Video Library

2017-05-18

NASA engineers install test hardware for the agency's new heavy lift rocket, the Space Launch System, into a newly constructed 50-foot structural test stand at NASA's Marshall Space Flight Center. In the stand, hydraulic cylinders will be electronically controlled to push, pull, twist and bend the test article with millions of pounds of force. Engineers will record and analyze over 3,000 channels of data for each test case to verify the capabilities of the engine section and validate that the design and analysis models accurately predict the amount of loads the core stage can withstand during launch and ascent. The engine section, recently delivered via NASA's barge Pegasus from NASA's Michoud Assembly Facility, is the first of four core stage structural test articles scheduled to be delivered to Marshall for testing. The engine section, located at the bottom of SLS's massive core stage, will house the rocket's four RS-25 engines and be an attachment point for the two solid rocket boosters.

Development of a remote-controlled fatigue test machine using a laser extensometer for investigation of irradiation effect on fatigue properties

NASA Astrophysics Data System (ADS)

Yonekawa, M.; Ishii, T.; Ohmi, M.; Takada, F.; Hoshiya, T.; Niimi, M.; Ioka, I.; Miwa, Y.; Tsuji, H.

2002-12-01

In order to investigate effects of neutron irradiation on fatigue properties of nuclear materials, a remote-controlled high temperature fatigue test machine was developed at the hot laboratory of the Japan Materials Testing Reactor (JMTR) in the Japan Atomic Energy Research Institute (JAERI). A small-sized fatigue specimen having double blades to measure strain with a laser extensometer was designed for this machine. A strain amplitude in fatigue tests of a completely reversed push-pull type using a triangular wave was controlled with an accuracy of ±3% of the total strain range during test. Low cycle fatigue tests of type 304 stainless steel irradiated in JMTR at 823 K up to a fast neutron fluence of 1×10 25 n/m 2 ( E>1 MeV) were performed in total strain ranges of 0.7-1.4% at 823 K using the designed small-sized specimens.

Getting By: A "Lost Generation" Member's Local History of the College Extracurriculum

ERIC Educational Resources Information Center

Rohan, Liz

2014-01-01

This article features the diaries and letters of a college student, John Price, who attended Denison University from 1917 to 1921. It shows how Price was pushed and pulled into writing in the extracurriculum by his literacy sponsors, which resulted in his founding a humor magazine as "the jock" took over as "the big man on college…

Power Divider for Waveforms Rich in Harmonics

NASA Technical Reports Server (NTRS)

Sims, William Herbert, III

2005-01-01

A method for dividing the power of an electronic signal rich in harmonics involves the use of an improved divider topology. A divider designed with this topology could be used, for example, to propagate a square-wave signal in an amplifier designed with a push-pull configuration to enable the generation of more power than could be generated in another configuration.

The "Push and Pull" of Home Schooling in the Larger Society: Using an Epidemiological Lens To Study an Educational Phenomenon.

ERIC Educational Resources Information Center

McDowell, Susan A.

This paper analyzes whether certain events in society influence educational choice, in particular, the choice to home school children. Using an epidemiological approach, the article analyzes the perceptions of home-school leaders and others involved in the movement, focusing on the substantive influence of events on the home-schooling movement. It…

The 'Push and Pull' Factors of Distributed Leadership: Exploring Views of Headteachers across Two Countries

ERIC Educational Resources Information Center

Dampson, Dandy George; Frempong, Evelyn Ama

2018-01-01

Governments and other stakeholders in education are beginning to recognize the important roles school leaders can play in school development and efforts are being made to allow them to become more involved in managing schools. However, despite these efforts, head teachers are challenged with the perfect leadership style to improve schools. Many…

Push-Pull Factors of Undocumented Migration from Bangladesh to West Bengal: A Perception Study

ERIC Educational Resources Information Center

Datta, Pranati

2004-01-01

Movement is an integral part of human existence. While talking about transborder migration from Bangladesh to India, we are, however, aware that this is a controversial subject. The partition of Bengal in 1947 was the cruelest partition in the history of the world and caused forced illegal migration from erstwhile East Pakistan. It is estimated…

75 FR 20423 - Fuji Heavy Industries USA, Inc., Receipt of Petition for Decision of Inconsequential Noncompliance

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-19

... power supply to the lamp. The Company said that ``installation of the wiring harness to the... subsupplier such that tension was put on the wiring harness connector'' which can cause it to come loose. To correct this problem, the Company has re-routed the wiring harness to ``push'' rather than ``pull'' on the...

The Private Military Firms: Historical Evolution and Industry Analysis

DTIC Science & Technology

2007-06-01

Company, Private Military Firm, Supply Push, Demand Pull, Future Projections, Blackwater, DynCorp, Entrepreneurship 16. PRICE CODE 17. SECURITY...Business Administration, University of California, 1995. Baumol, W. J. Entrepreneurship , Management, and the Structure of Payoffs. Cambridge, MA: The MIT...P. F. Innovation and Entrepreneurship : Practice and Principles. Toronto: Fitzhenry & Whiteside Limited, 1985. Duffy, M. When Private Armies Take to

Changes and Challenges in the Flow of International Human Capital: China's Experience

ERIC Educational Resources Information Center

Pan, Su-Yan

2010-01-01

This article tracks the changes in the directions of the international flow of Chinese human capital between the 1870s and 2000s. Although many studies on international academic flow adopt the pull-and-push approach, this article argues that the direction of human capital flow is not determined solely by an individual's choice when faced with a…

Why good ideas and good science do not always make it into the marketplace

Treesearch

Charles R. Frihart

2007-01-01

Good ideas and good science are not sufficient in and of themselves for successful commercialization of new technology. Understanding the barriers to commercialization so that ways around, under, over, or through them can be found is also crucial to success. Barriers can include market needs, technology push versus market pull, availability of a window of opportunity,...

Effects of load position and force direction on back muscle loading in one-wheeled wheelbarrow tasks.

PubMed

Chen, Su-Huang; Lee, Yung-Hui; Lin, Chiuhsiang Joe

2015-01-01

Various parameters related to pushing/pulling tasks have been examined yet the effects of changing the load position in one-wheeled wheelbarrow task has not been examined. To explore the effects of load position and force direction on muscle activity during wheelbarrow tasks. Nine participants were recruited to take part in the experiment. Each participant performed 18 trials consisting of 2 force directions (push and pull) and 9 load positions. The dependent variables were EMG of erector spinae and gripping force. ANOVA was used to identify significant differences between force direction and load position in EMG and gripping force data. Results showed that peak EMG was lowest for the left and right erector spinae when the load was positioned farther from the participant. Peak EMG of the bilateral erector spinae increased when the weight was near the participant and on the ipsilateral hand. Based on the EMG results, we suggest that loads be arranged in the anterior part of the bin in order to reduce muscle activity on the spine during the wheelbarrow task. This finding also provides some directions in the improvement and ergonomic redesign of the one-wheeled wheelbarrow.

High temporal resolution coupling of low-flow push-pull perfusion to capillary electrophoresis for ascorbate analysis at the rat vitreoretinal interface.

PubMed

Patterson, Eric E; Pritchett, Jeanita S; Shippy, Scott A

2009-02-01

A system is presented demonstrating the high-temporal resolution coupling of low-flow push-pull perfusion sampling (LFPS) to capillary electrophoresis for the absorbance measurement of ascorbate at the rat vitreoretinal interface. This system holds all separation components at a low pressure as the means for withdrawing sample during LFPS. The system uses a flow-gated interface to directly couple the withdrawal capillary from the LFPS probe to a separation capillary and eliminates the need for any offline sample handling. The temporal resolution of the system was limited by injection time and is less than 16 s. This high temporal resolution was applied to the monitoring of in vivo ascorbate levels at the rat vitreoretinal interface. Baseline concentrations of ascorbate were found to be 86 microM +/- 18 microM at the vitreoretinal interface. Baseline concentrations matched well with those obtained for the postmortem bulk vitreous analysis. Upon stimulation with 145 mM K(+), a maximum increase in baseline values between 32-107% for n = 3 was observed. This system demonstrates the first in vivo temporal study of ascorbate at the rat vitreoretinal interface.

Improved Quick-Release Pin Mechanism

NASA Technical Reports Server (NTRS)

Wright, Jay M.

2007-01-01

An improved quick-release pin mechanism supplants a prior such mechanism in which the pin bears a shear load to hold two objects together. The prior mechanism, of a ball-locking design, can fail when vibrations cause balls to fall out. The load-bearing pin is an outer tube with a handle at one end (hereafter denoted the near end). Within the outer tube is a spring-loaded inner tube that includes a handle at its near end and a pivoting tab at its far end. The pin is inserted through holes in the objects to be retained and the inner tube is pushed against an offset pivot inside the outer tube to make the tab rotate outward so that it protrudes past the outer diameter of the outer tube, and the spring load maintains this configuration so that the pin cannot be withdrawn through the holes. Pushing the handles together against the spring load moves the locking tab out far enough that the tab becomes free to rotate inward. Then releasing the inner-tube handle causes the tab to be pulled into a resting position inside the outer tube. The pin can then be pulled out through the holes.

The global workforce shortages and the migration of medical professions: the Australian policy response

PubMed Central

Smith, Saxon D

2008-01-01

Medical migration sees the providers of medical services (in particular medical practitioners) moving from one region or country to another. This creates problems for the provision of public health and medical services and poses challenges for laws in the nation state and for laws in the global community. There exists a global shortage of healthcare professionals. Nation states and health rights movements have been both responsible for, and responsive to, this global community shortage through a variety of health policy, regulation and legislation which directly affects the migration of medical providers. The microcosm responses adopted by individual nation states, such as Australia, to this workforce shortage further impact on the global workforce shortage through active recruitment of overseas-trained healthcare professionals. "Push" and "pull" factors exist which encourage medical migration of healthcare professionals. A nation state's approach to health policy, regulation and legislation dramatically helps to create these "push factors" and "pull factors". A co-ordinated global response is required with individual nation states being cognisant of the impact of their health policy, regulations and legislation on the global community through the medical migration of healthcare professionals. PMID:18507867

International migration of health professionals and the marketization and privatization of health education in India: from push-pull to global political economy.

PubMed

Walton-Roberts, Margaret

2015-01-01

Health worker migration theories have tended to focus on labour market conditions as principal push or pull factors. The role of education systems in producing internationally oriented health workers has been less explored. In place of the traditional conceptual approaches to understanding health worker, especially nurse, migration, I advocate global political economy (GPE) as a perspective that can highlight how educational investment and global migration tendencies are increasing interlinked. The Indian case illustrates the globally oriented nature of health care training, and informs a broader understanding of both the process of health worker migration, and how it reflects wider marketization tendencies evident in India's education and health systems. The Indian case also demonstrates how the global orientation of education systems in source regions is increasingly central to comprehending the place of health workers in the global and Asian rise in migration. The paper concludes that Indian corporate health care training systems are increasingly aligned with the production of professionals orientated to globally integrated health human resource labour markets, and our conceptual analysis of such processes must effectively reflect these tendencies. Copyright © 2014 Elsevier Ltd. All rights reserved.

Selective two-photon absorption in carbon dots: a piece of the photoluminescence emission puzzle.

PubMed

Santos, Carla I M; Mariz, Inês F A; Pinto, Sandra N; Gonçalves, Gil; Bdikin, Igor; Marques, Paula A A P; Neves, Maria Graça P M S; Martinho, José M G; Maçôas, Ermelinda M S

2018-06-22

Carbon nanodots (Cdots) are now emerging as promising nonlinear fluorophores for applications in biological environments. A thorough and systematic approach to the two-photon induced emission of Cdots that could provide design guidelines to control their nonlinear emission properties is still missing. In this work, we address the nonlinear optical spectroscopy of Cdots prepared by controlled chemical cutting of graphene oxide (GO). The two-photon absorption in the 700-1000 nm region and the corresponding emission spectrum are carefully investigated. The highest two-photon absorption cross-section estimated was 130 GM at 720 nm. This value is comparable with the one reported for graphene nanoribbons with push-pull architecture. The emission spectrum depends on the excitation mode. At the same excitation energy, nonlinear excitation results in excitation-wavelength independent emission, while upon linear excitation the emission is excitation-wavelength dependent. The biphotonic interaction seems to be selective towards sp2 clusters bearing electron donor and acceptor groups found in push-pull architectures. Both linear and nonlinear emission can be understood based on the existence of isolated sp2 clusters involved in π-π stacking interactions with clusters in adjacent layers.

Muscle activity and spine load during pulling exercises: influence of stable and labile contact surfaces and technique coaching.

PubMed

McGill, Stuart M; Cannon, Jordan; Andersen, Jordan T

2014-10-01

This study examined pulling exercises performed on stable surfaces and unstable suspension straps. Specific questions included: which exercises challenged particular muscles, what was the magnitude of resulting spine load, and did technique coaching influence results. Fourteen males performed pulling tasks while muscle activity, external force, and 3D body segment motion were recorded. These data were processed and input to a sophisticated and anatomically detailed 3D model that used muscle activity and body segment kinematics to estimate muscle force, in this way the model was sensitive to each individual's choice of motor control for each task. Muscle forces and linked segment joint loads were used to calculate spine loads. There were gradations of muscle activity and spine load characteristics to every task. It appears that suspension straps alter muscle activity less in pulling exercises, compared to studies reporting on pushing exercises. The chin-up and pull-up exercises created the highest spine load as they required the highest muscle activation, despite the body "hanging" under tractioning gravitational load. Coaching shoulder centration through retraction increased spine loading but undoubtedly adds proximal stiffness. An exercise atlas of spine compression was constructed to help with the decision making process of exercise choice for an individual. Copyright © 2014 Elsevier Ltd. All rights reserved.

Measurement of food-related approach-avoidance biases: Larger biases when food stimuli are task relevant.

PubMed

Lender, Anja; Meule, Adrian; Rinck, Mike; Brockmeyer, Timo; Blechert, Jens

2018-06-01

Strong implicit responses to food have evolved to avoid energy depletion but contribute to overeating in today's affluent environments. The Approach-Avoidance Task (AAT) supposedly assesses implicit biases in response to food stimuli: Participants push pictures on a monitor "away" or pull them "near" with a joystick that controls a corresponding image zoom. One version of the task couples movement direction with image content-independent features, for example, pulling blue-framed images and pushing green-framed images regardless of content ('irrelevant feature version'). However, participants might selectively attend to this feature and ignore image content and, thus, such a task setup might underestimate existing biases. The present study tested this attention account by comparing two irrelevant feature versions of the task with either a more peripheral (image frame color: green vs. blue) or central (small circle vs. cross overlaid over the image content) image feature as response instruction to a 'relevant feature version', in which participants responded to the image content, thus making it impossible to ignore that content. Images of chocolate-containing foods and of objects were used, and several trait and state measures were acquired to validate the obtained biases. Results revealed a robust approach bias towards food only in the relevant feature condition. Interestingly, a positive correlation with state chocolate craving during the task was found when all three conditions were combined, indicative of criterion validity of all three versions. However, no correlations were found with trait chocolate craving. Results provide a strong case for the relevant feature version of the AAT for bias measurement. They also point to several methodological avenues for future research around selective attention in the irrelevant versions and task validity regarding trait vs. state variables. Copyright © 2018 Elsevier Ltd. All rights reserved.

Pharmaceutical drug marketing strategies and tactics: a comparative analysis of attitudes held by pharmaceutical representatives and physicians.

PubMed

Parker, R Stephen; Pettijohn, Charles E

2005-01-01

A variety of promotional strategies have been used to stimulate sales of pharmaceutical drugs. Traditionally, push techniques have been the predominant means used to encourage physicians to prescribe drugs and thus increase sales. Recently, the traditional push strategy has been supplemented by a pull strategy. Direct-to-consumer advertising is increasingly used to encourage consumers to request advertised drugs from their physicians. This research compares the attitudes of two of the most affected participants in the prescriptive sales processes; physicians and pharmaceutical sales representatives. The findings indicate differences between physicians and pharmaceutical sales representatives regarding the efficacy and ethical considerations of various promotional strategies.

The Contributions of Immigrants to American Culture

PubMed Central

Hirschman, Charles

2013-01-01

The standard account of American immigration focuses on the acculturation and assimilation of immigrants and their children to American society. This analysis typically ignores the significant contributions of immigrants to the creation of American culture through the performing arts, sciences, and other cultural pursuits. Immigrants and their children are not born with more creative talents than native-born citizens, but their selectivity and marginality may have pushed and pulled those with ability into high-risk career paths that reward creative work. The presence of large numbers of talented immigrants in Hollywood, academia, and the high-tech industries has pushed American institutions to be more meritocratic and open to innovation than they would be otherwise. PMID:24339451

Motor abilities and anthropometrics in youth cross-country skiing.

PubMed

Stöggl, R; Müller, E; Stöggl, T

2015-02-01

The purposes were to validate whether general motor abilities and anthropometrics are determinants of youth cross-country (XC) skiing performance; evaluate gender-specific differences; and to establish noninvasive diagnostics. Fifty-one youth XC skiers (34 boys; 13.8 ± 0.6 years and 17 girls; 13.4 ± 0.9 years) performed motor skill and laboratory tests, and anthropometric data were collected and correlated with XC skiing performance. Anthropometrics and maturity status were related to boys but not to girls XC skiing performance. Push-ups and 20-m sprint were correlated to XC skiing performance in both boys and girls. XC skiing performance of boys was predominantly influenced by upper body and trunk strength capacities (medicine ball throw, push-ups, and pull-ups) and jumping power (standing long and triple jump), whereas XC skiing of girls was mainly influenced by aerobic capacities (3000-m run). Laboratory measures did not reveal greater correlations to XC skiing performance compared with simple test concepts of speed, strength, and endurance. Maturity was a major confounding variable in boys but not girls. Use of noninvasive simple test concepts for determination of upper body strength, speed, and endurance represent practicable support for ski clubs, schools, or skiing federations in the guidance and evaluation of young talent, being aware of the effect of maturity especially in boys. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Casingless down-hole for sealing an ablation volume and obtaining a sample for analysis

DOEpatents

Noble, Donald T.; Braymen, Steven D.; Anderson, Marvin S.

1996-10-01

A casing-less down hole sampling system for acquiring a subsurface sample for analysis using an inductively coupled plasma system is disclosed. The system includes a probe which is pushed into the formation to be analyzed using a hydraulic ram system. The probe includes a detachable tip member which has a soil point mad a barb, with the soil point aiding the penetration of the earth, and the barb causing the tip member to disengage from the probe and remain in the formation when the probe is pulled up. The probe is forced into the formation to be tested, and then pulled up slightly, to disengage the tip member and expose a column of the subsurface formation to be tested. An instrumentation tube mounted in the probe is then extended outward from the probe to longitudinally extend into the exposed column. A balloon seal mounted on the end of the instrumentation tube allows the bottom of the column to be sealed. A source of laser radiation is emitted from the instrumentation tube to ablate a sample from the exposed column. The instrumentation tube can be rotated in the probe to sweep the laser source across the surface of the exposed column. An aerosol transport system carries the ablated sample from the probe to the surface for testing in an inductively coupled plasma system. By testing at various levels in the down-hole as the probe is extracted from the soil, a profile of the subsurface formation may be obtained.

Theoretical and experimental study of organic nano-material for acetate anion based on 1, 10-phenanthroline.

PubMed

Shang, Xuefang; Zhao, Yuan; Wei, Xiaofang; Feng, Yaqian; Li, Xin; Gao, Shuyan; Xu, Xiufang

2015-01-01

New phenanthroline derivatives (1, 2, 3, 4) containing phenol groups have been synthesized and optimized. The nano-material of compound 2 was also developed. Their binding properties were evaluated for various biological anions (F(-), Cl(-), Br(-), I(-), AcO(-) and H(2)PO(4)(-)) by theoretical investigation, UV-vis, fluorescence, (1)HNMR titration experiments and these compounds all showed strong binding ability for AcO(-) without the interference of other anions tested. The anion binding ability could be regularized by electron push-pull properties of the ortho- or para- substituent on benzene. Theoretical investigation analysis revealed the effect of intramolecular hydrogen bond existed between -OH and other atoms in the structure of these compounds.

Modeling the macrodynamics of international migration: determinants of emigration from Cyprus, 1946-85.

PubMed

Diamantides, N D; Constantinou, S T

1989-07-01

"A model is presented of international migration that is based on the concept of a pool of potential emigrants at the origin created by push-pull forces and by the establishment of information feedback between origin and destination. The forces can be economic, political, or both, and are analytically expressed by the 'mediating factor'. The model is macrodynamic in nature and provides both for the main secular component of the migratory flow and for transient components caused by extraordinary events. The model is expressed in a Bernoulli-type differential equation through which quantitative weights can be derived for each of the operating causes. Out-migration from the Republic of Cyprus is used to test the tenets of the model." excerpt

The process of desistance among core ex-gang members.

PubMed

Berger, Rony; Abu-Raiya, Hisham; Heineberg, Yotam; Zimbardo, Philip

2017-01-01

Research has established robust links between gang membership, delinquency, violence and victimization. Yet studies examining the process of gang desistance in general and that of core gang members in particular, are quite rare. The current study aims to identify factors associated with desistance of core gang members as well as describe the nature of the process that these "formers" have undergone. Thirty-nine core ex-gang members (80% males and 20% females) from the San Francisco Bay area and Los Angeles, with an average length of 11.6-years gang membership, were interviewed regarding their involvement in the gang and the desistance process. A systematic qualitative analysis based on grounded theory methodology was mainly utilized. We found that the decision to leave the gang is a result of a combination of push (e.g., personal and vicarious victimization, burnout of gang lifestyle, disillusionment by the gang) and pull (e.g., parenthood, family responsibilities, religious and cultural awakening) factors that evolved over time. Push factors were more dominant in this domain. We also found that while male core ex-gang members tended to leave the gang more frequently because of push factors, female ex-gang members were more inclined to desist due to pull factors. Our analysis also showed that core gang members shared a general pattern of the desistance process comprising of the following 5 stages: triggering, contemplation, exploration, exiting and maintenance. Based on these results, we outlined stage-specific recommendations for agents of societal change to help in facilitating the desistance of core gang members. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Interpretation of the lime column penetration test

NASA Astrophysics Data System (ADS)

Liyanapathirana, D. S.; Kelly, R. B.

2010-06-01

Dry soil mix (DSM) columns are used to reduce the settlement and to improve the stability of embankments constructed on soft clays. During construction the shear strength of the columns needs to be confirmed for compliance with technical assumptions. A specialized blade shaped penetrometer known as the lime column probe, has been developed for testing DSM columns. This test can be carried out as a pull out resistance test (PORT) or a push in resistance test (PIRT). The test is considered to be more representative of average column shear strength than methods that test only a limited area of the column. Both PORT and PIRT tests require empirical correlations of measured resistance to an absolute measure of shear strength, in a similar manner to the cone penetration test. In this paper, finite element method is used to assess the probe factor, N, for the PORT test. Due to the large soil deformations around the probe, an Arbitrary Lagrangian Eulerian (ALE) based finite element formulation has been used. Variation of N with rigidity index and the friction at the probe-soil interface are investigated to establish a range for the probe factor.

Coal-Sizing Auger

NASA Technical Reports Server (NTRS)

Lewis, E. V.

1985-01-01

Aft end of auger, like forward, face-piercing end, equipped with hard cutting bits such as diamonds. As auger breaks face, pulls broken coal lumps into jaws and forces them into hardened throat section. There, cutting bits chew up lumps: Clearance between throat and auger shaft sets maximum size for coal particles that pass through. Auger motion pushes coal particles into mixing chamber, where paddles combine them with water.

Dropping Out of School in Southern Ghana: The Push-Out and Pull-Out Factors. CREATE Pathways to Access. Research Monograph No. 55

ERIC Educational Resources Information Center

Ananga, Eric

2011-01-01

Addressing school dropout has been one of the most controversial elements of policy since the introduction of free compulsory universal basic education (FCUBE) in Ghana. However, research that utilises qualitative biographical detail surrounding irregular attendance and the critical events in the process that lead to dropout in Ghana is limited. I…

All about Forces & Gravity. Physical Science for Children[TM]. Schlessinger Science Library. [Videotape].

ERIC Educational Resources Information Center

2000

A force is a push or a pull. In All About Forces and Gravity, kids will join our host on a parasailing adventure to investigate how forces impact and shape everything that happens in the world around us. Learn about gravity and the work of Sir Isaac Newton, the English scientists whose scientific principles forever changed the way people looked at…

Global Broadcast Service (GBS)

DTIC Science & Technology

2013-12-01

as to be unusable by smaller and more mobile units. To this end, GBS currently uses broadcast payloads on two Ultra-High Frequency Follow-On ( UFO ...operational on UFO satellites 8, 9, 10. - Full Satellite Broadcast Manager capability. - Field 20% of JPO Receive Suites (19 units). - Personnel training...capabilities. - Augment UFO GBS with leased commercial satellite services to cover gaps over CONUS. - Demonstrate smart push and user pull capability

Human migration and natural resources: implications for land managers and challenges for researchers.

Treesearch

Stephen F. McCool; Linda E. Kruger

2003-01-01

Rural areas of the Pacific Northwest experienced a dramatic growth in population during the late 1980s to early 1990s. This growth was fueled by both push and pull factors, including environmental and natural resource based amenities. Such growth has not only stressed the capacity of rural counties and communities to cope with change but also has raised important...

Pushing and Pulling Sara: A Case Study of the Contrasting Influences of High School and University Experiences on Engineering Agency, Identity, and Participation

ERIC Educational Resources Information Center

Godwin, Allison; Potvin, Geoff

2017-01-01

This manuscript reports a longitudinal case study of how one woman, Sara, who had previously considered dropping out of high school, authored strong mathematics and science identities and purposefully exhibited agency through her experiences in high school science. These experiences empowered her to choose an engineering major in college; however,…

Hang Gliders for Sport

NASA Technical Reports Server (NTRS)

1976-01-01

Hang gliding is growing rapidly. Free Flight produces 1,000 gliders a month and other companies are entering the field. Wing is simple to control, pulling back on control bar allows you to pick up speed and at the same time lowers your altitude. Pushing forward slows your speed and levels you off. Birdmen can choose from prone, upright or swing seat harnesses in either kits or ready-to-fly gliders.

Examining the Motives and the Future Career Intentions of Mainland Chinese Pre-Service Teachers in Hong Kong

ERIC Educational Resources Information Center

Cheung, Alan C. K.; Yuen, Timothy W. W.

2016-01-01

The purpose of this paper was to examine the motives, the educational experiences, and the plan after graduation of a particular group of mainland Chinese students pursuing teacher education in Hong Kong by using a modified two-way push-and-pull model as our analytical framework. The study employed both quantitative and qualitative methods.…

Student Enrollment and Dropout: An Evaluation Study of DCSA Program at Bangladesh Open University

ERIC Educational Resources Information Center

Rashid, Mohammad Mamunur; Jahan, Monira; Islam, Md. Anwarul; Ratna, Meherin Munjarin

2015-01-01

The aim of this study is to investigate the present status of DCSA program focusing on student enrollment, dropout, and completion trends. The study tries to explore the factors that attract or pull students to enroll in the program and push them to dropout from the program. Secondary data analysis and interview are used to generate data of the…

Force Generation upon T Cell Receptor Engagement

PubMed Central

Husson, Julien; Chemin, Karine; Bohineust, Armelle; Hivroz, Claire; Henry, Nelly

2011-01-01

T cells are major players of adaptive immune response in mammals. Recognition of an antigenic peptide in association with the major histocompatibility complex at the surface of an antigen presenting cell (APC) is a specific and sensitive process whose mechanism is not fully understood. The potential contribution of mechanical forces in the T cell activation process is increasingly debated, although these forces are scarcely defined and hold only limited experimental evidence. In this work, we have implemented a biomembrane force probe (BFP) setup and a model APC to explore the nature and the characteristics of the mechanical forces potentially generated upon engagement of the T cell receptor (TCR) and/or lymphocyte function-associated antigen-1 (LFA-1). We show that upon contact with a model APC coated with antibodies towards TCR-CD3, after a short latency, the T cell developed a timed sequence of pushing and pulling forces against its target. These processes were defined by their initial constant growth velocity and loading rate (force increase per unit of time). LFA-1 engagement together with TCR-CD3 reduced the growing speed during the pushing phase without triggering the same mechanical behavior when engaged alone. Intracellular Ca2+ concentration ([Ca2+]i) was monitored simultaneously to verify the cell commitment in the activation process. [Ca2+]i increased a few tens of seconds after the beginning of the pushing phase although no strong correlation appeared between the two events. The pushing phase was driven by actin polymerization. Tuning the BFP mechanical properties, we could show that the loading rate during the pulling phase increased with the target stiffness. This indicated that a mechanosensing mechanism is implemented in the early steps of the activation process. We provide here the first quantified description of force generation sequence upon local bidimensional engagement of TCR-CD3 and discuss its potential role in a T cell mechanically-regulated activation process. PMID:21572959

Force generation upon T cell receptor engagement.

PubMed

Husson, Julien; Chemin, Karine; Bohineust, Armelle; Hivroz, Claire; Henry, Nelly

2011-05-10

T cells are major players of adaptive immune response in mammals. Recognition of an antigenic peptide in association with the major histocompatibility complex at the surface of an antigen presenting cell (APC) is a specific and sensitive process whose mechanism is not fully understood. The potential contribution of mechanical forces in the T cell activation process is increasingly debated, although these forces are scarcely defined and hold only limited experimental evidence. In this work, we have implemented a biomembrane force probe (BFP) setup and a model APC to explore the nature and the characteristics of the mechanical forces potentially generated upon engagement of the T cell receptor (TCR) and/or lymphocyte function-associated antigen-1 (LFA-1). We show that upon contact with a model APC coated with antibodies towards TCR-CD3, after a short latency, the T cell developed a timed sequence of pushing and pulling forces against its target. These processes were defined by their initial constant growth velocity and loading rate (force increase per unit of time). LFA-1 engagement together with TCR-CD3 reduced the growing speed during the pushing phase without triggering the same mechanical behavior when engaged alone. Intracellular Ca(2+) concentration ([Ca(2+)](i)) was monitored simultaneously to verify the cell commitment in the activation process. [Ca(2+)](i) increased a few tens of seconds after the beginning of the pushing phase although no strong correlation appeared between the two events. The pushing phase was driven by actin polymerization. Tuning the BFP mechanical properties, we could show that the loading rate during the pulling phase increased with the target stiffness. This indicated that a mechanosensing mechanism is implemented in the early steps of the activation process. We provide here the first quantified description of force generation sequence upon local bidimensional engagement of TCR-CD3 and discuss its potential role in a T cell mechanically-regulated activation process.

Gender determinants of smoking practice in Indigenous communities: an exploratory study.

PubMed

Knott, V E; Gilligan, G; Maksimovic, L; Shen, D; Murphy, M

2016-03-01

Despite the need to urgently reduce smoking rates among Indigenous Australians, in order to close-the-gap in life expectancy, little is known regarding how this can be achieved. This study aimed to explore whether a focus on gender specific determinants of smoking among Indigenous Australians could be identified, thus providing a potentially novel approach to underpin future efforts at intervention. A qualitative research design was employed. Eighty-two participants, comprised of 43 Indigenous women (mean age 32.15, SD, 12.47) and 39 Indigenous men (mean age 34.91, SD, 11.26), participated in one of 12 focus groups held in metropolitan, regional and rural locations in South Australia. Facilitators prompted discussion in response to the question: 'What is it like being a smoker these days?' Two experienced coders assessed data for themes using Attride-Stirling's (2002) method of analysis. Two global themes emerged for men and women. The first theme, 'It's Harder to Smoke Nowadays', encompassed sub-themes capturing changed smoking practices in response to tobacco control strategies implemented in Australia. Sub-themes of 'smoking in secrecy' coupled with an 'awareness of the effects of passive smoking' were identified among women. Among men, sub-themes that depicted tension between 'a desire to be a role model' and 'guilt about smoking' emerged. The second theme, 'Push and Pull Factors', identified a range of gender specific determinants of smoking. While similar reasons for smoking ('pull factors') were identified in men and women (e.g. addiction, boredom, stress, pleasure, mood stabiliser), different 'push factors' (reasons for not wanting to smoke) emerged. For men, sport, fitness and children were identified as reasons for not wanting to smoke, whereas women identified factors such as respect for non-smokers, and body image concerns. The current findings suggest that there may be fundamental differences in the determinants of smoking (pull factors) as well as reasons for wanting to quit (push factors) between Indigenous men and women. A focus on interventions that target gender specific determinants, or motivators of smoking, offers a novel, and potentially efficacious approach to reduce smoking rates among Indigenous Australians. © 2016 John Wiley & Sons Ltd.

Effects of Bulky Substituents of Push-Pull Porphyrins on Photovoltaic Properties of Dye-Sensitized Solar Cells.

PubMed

Higashino, Tomohiro; Kawamoto, Kyosuke; Sugiura, Kenichi; Fujimori, Yamato; Tsuji, Yukihiro; Kurotobi, Kei; Ito, Seigo; Imahori, Hiroshi

2016-06-22

To evaluate the effects of substituent bulkiness around a porphyrin core on the photovoltaic properties of porphyrin-sensitized solar cells, long alkoxy groups were introduced at the meso-phenyl group (ZnPBAT-o-C8) and the anchoring group (ZnPBAT-o-C8Cn, n = 4, 8) of an asymmetrically substituted push-pull porphyrin with double electron-donating diarylamino groups and a single electron-withdrawing carboxyphenylethynyl anchoring group. The spectroscopic and electrochemical properties of ZnPBAT-o-C8 and ZnPBAT-o-C8Cn were found to be superior to those of a push-pull porphyrin reference (YD2-o-C8), demonstrating their excellent light-harvesting and redox properties for dye-sensitized solar cells. A power conversion efficiency (η) of the ZnPBAT-o-C8-sensitized solar cell (η = 9.1%) is higher than that of the YD2-o-C8-sensitized solar cell (η = 8.6%) using iodine-based electrolyte due to the enhanced light-harvesting ability of ZnPBAT-o-C8. In contrast, the solar cells based on ZnPBAT-o-C8Cn, possessing the additional alkoxy chains in the anchoring group, revealed the lower η values of 7.3% (n = 4) and 7.0% (n = 8). Although ZnPBAT-o-C8Cn exhibited higher resistance at the TiO2-dye-electrolyte interface by virtue of the extra alkoxy chains, the reduced amount of the porphyrins on TiO2 by excessive addition of coadsorbent chenodeoxycholic acid (CDCA) for mitigating the aggregation on TiO2 resulted in the low η values. Meanwhile, the ZnPBAT-o-C8-sensitized solar cell showed the lower η value of 8.1% than the YD2-o-C8-sensitized solar cell (η = 9.8%) using cobalt-based electrolyte. The smaller η value of the ZnPBAT-o-C8-sensitized solar cell may be attributed to the insufficient blocking effect of the bulky substituents of ZnPBAT-o-C8 under the cobalt-based electrolyte conditions. Overall, the alkoxy chain length and substitution position around the porphyrin core are important factors to affect the cell performance.

Conserved phosphoryl transfer mechanisms within kinase families and the role of the C8 proton of ATP in the activation of phosphoryl transfer

PubMed Central

2012-01-01

Background The kinome is made up of a large number of functionally diverse enzymes, with the classification indicating very little about the extent of the conserved kinetic mechanisms associated with phosphoryl transfer. It has been demonstrated that C8-H of ATP plays a critical role in the activity of a range of kinase and synthetase enzymes. Results A number of conserved mechanisms within the prescribed kinase fold families have been identified directly utilizing the C8-H of ATP in the initiation of phosphoryl transfer. These mechanisms are based on structurally conserved amino acid residues that are within hydrogen bonding distance of a co-crystallized nucleotide. On the basis of these conserved mechanisms, the role of the nucleotide C8-H in initiating the formation of a pentavalent intermediate between the γ-phosphate of the ATP and the substrate nucleophile is defined. All reactions can be clustered into two mechanisms by which the C8-H is induced to be labile via the coordination of a backbone carbonyl to C6-NH2 of the adenyl moiety, namely a "push" mechanism, and a "pull" mechanism, based on the protonation of N7. Associated with the "push" mechanism and "pull" mechanisms are a series of proton transfer cascades, initiated from C8-H, via the tri-phosphate backbone, culminating in the formation of the pentavalent transition state between the γ-phosphate of the ATP and the substrate nucleophile. Conclusions The "push" mechanism and a "pull" mechanism are responsible for inducing the C8-H of adenyl moiety to become more labile. These mechanisms and the associated proton transfer cascades achieve the proton transfer via different family-specific conserved sets of amino acids. Each of these mechanisms would allow for the regulation of the rate of formation of the pentavalent intermediate between the ATP and the substrate nucleophile. Phosphoryl transfer within kinases is therefore a specific event mediated and regulated via the coordination of the adenyl moiety of ATP and the C8-H of the adenyl moiety. PMID:22397702

A new approach for flow-through respirometry measurements in humans

PubMed Central

Ingebrigtsen, Jan P.; Bergouignan, Audrey; Ohkawara, Kazunori; Kohrt, Wendy M.; Lighton, John R. B.

2010-01-01

Indirect whole room calorimetry is commonly used in studies of human metabolism. These calorimeters can be configured as either push or pull systems. A major obstacle to accurately calculating gas exchange rates in a pull system is that the excurrent flow rate is increased above the incurrent flow rate, because the organism produces water vapor, which also dilutes the concentrations of respiratory gasses in the excurrent sample. A common approach to this problem is to dry the excurrent gasses prior to measurement, but if drying is incomplete, large errors in the calculated oxygen consumption will result. The other major potential source of error is fluctuations in the concentration of O2 and CO2 in the incurrent airstream. We describe a novel approach to measuring gas exchange using a pull-type whole room indirect calorimeter. Relative humidity and temperature of the incurrent and excurrent airstreams are measured continuously using high-precision, relative humidity and temperature sensors, permitting accurate measurement of water vapor pressure. The excurrent flow rates are then adjusted to eliminate the flow contribution from water vapor, and respiratory gas concentrations are adjusted to eliminate the effect of water vapor dilution. In addition, a novel switching approach is used that permits constant, uninterrupted measurement of the excurrent airstream while allowing frequent measurements of the incurrent airstream. To demonstrate the accuracy of this approach, we present the results of validation trials compared with our existing system and metabolic carts, as well as the results of standard propane combustion tests. PMID:20200135

Stiefel-Whitney classes of curve covers

NASA Astrophysics Data System (ADS)

Selander, Björn

2016-10-01

Let D be a Dedekind scheme with the characteristic of all residue fields not equal to 2. To every tame cover Cto D with only odd ramification we associate a second Stiefel-Whitney class in the second cohomology with mod 2 coefficients of a certain tame orbicurve [D] associated to D. This class is then related to the pull-back of the second Stiefel-Whitney class of the push-forward of the line bundle of half of the ramification divisor. This shows (indirectly) that our Stiefel-Whitney class is the pull-back of a sum of cohomology classes considered by Esnault, Kahn and Viehweg in `Coverings with odd ramification and Stiefel-Whitney classes'. Perhaps more importantly, in the case of a proper and smooth curve over an algebraically closed field, our Stiefel-Whitney class is shown to be the pull-back of an invariant considered by Serre in `Revêtements à ramification impaire et thêta-caractéristiques', and in this case our arguments give a new proof of the main result of that article.

Tug of war in motility assay experiments

NASA Astrophysics Data System (ADS)

Hexner, Daniel; Kafri, Yariv

2009-09-01

The dynamics of two groups of molecular motors pulling in opposite directions on a rigid filament is studied theoretically. To this end we first consider the behavior of one set of motors pulling in a single direction against an external force using a new mean-field approach. Based on these results we analyze a similar setup with two sets of motors pulling in opposite directions in a tug of war in the presence of an external force. In both cases we find that the interplay of fluid friction and protein friction leads to a complex phase diagram where the force-velocity relations can exhibit regions of bistability and spontaneous symmetry breaking. Finally, motivated by recent work, we turn to the case of motility assay experiments where motors bound to a surface push on a bundle of filaments. We find that, depending on the absence or the presence of bistability in the force-velocity curve at zero force, the bundle exhibits anomalous or biased diffusion on long-time and large-length scales.

How graphene slides: measurement and theory of strain-dependent frictional forces between graphene and SiO2.

PubMed

Kitt, Alexander L; Qi, Zenan; Rémi, Sebastian; Park, Harold S; Swan, Anna K; Goldberg, Bennett B

2013-06-12

Strain, bending rigidity, and adhesion are interwoven in determining how graphene responds when pulled across a substrate. Using Raman spectroscopy of circular, graphene-sealed microchambers under variable external pressure, we demonstrate that graphene is not firmly anchored to the substrate when pulled. Instead, as the suspended graphene is pushed into the chamber under pressure, the supported graphene outside the microchamber is stretched and slides, pulling in an annulus. Analyzing Raman G band line scans with a continuum model extended to include sliding, we extract the pressure dependent sliding friction between the SiO2 substrate and mono-, bi-, and trilayer graphene. The sliding friction for trilayer graphene is directly proportional to the applied load, but the friction for monolayer and bilayer graphene is inversely proportional to the strain in the graphene, which is in violation of Amontons' law. We attribute this behavior to the high surface conformation enabled by the low bending rigidity and strong adhesion of few layer graphene.

Actomyosin Pulls to Advance the Nucleus in a Migrating Tissue Cell

PubMed Central

Wu, Jun; Kent, Ian A.; Shekhar, Nandini; Chancellor, T.J.; Mendonca, Agnes; Dickinson, Richard B.; Lele, Tanmay P.

2014-01-01

The cytoskeletal forces involved in translocating the nucleus in a migrating tissue cell remain unresolved. Previous studies have variously implicated actomyosin-generated pushing or pulling forces on the nucleus, as well as pulling by nucleus-bound microtubule motors. We found that the nucleus in an isolated migrating cell can move forward without any trailing-edge detachment. When a new lamellipodium was triggered with photoactivation of Rac1, the nucleus moved toward the new lamellipodium. This forward motion required both nuclear-cytoskeletal linkages and myosin activity. Apical or basal actomyosin bundles were found not to translate with the nucleus. Although microtubules dampen fluctuations in nuclear position, they are not required for forward translocation of the nucleus during cell migration. Trailing-edge detachment and pulling with a microneedle produced motion and deformation of the nucleus suggestive of a mechanical coupling between the nucleus and the trailing edge. Significantly, decoupling the nucleus from the cytoskeleton with KASH overexpression greatly decreased the frequency of trailing-edge detachment. Collectively, these results explain how the nucleus is moved in a crawling fibroblast and raise the possibility that forces could be transmitted from the front to the back of the cell through the nucleus. PMID:24411232

Launch Vehicle Stage Adapter from Start to Stack

NASA Image and Video Library

2016-10-16

See how a test version of the launch vehicle stage adapter (LVSA) for NASA's new rocket, the Space Launch System, is designed, built and stacked in a test stand at the agency's Marshall Space Flight Center in Huntsville, Alabama. The LVSA was moved to a 65-foot-tall test stand Oct. 12 at Marshall. The test version LVSA will be stacked with other test pieces of the upper part of the SLS rocket and pushed, pulled and twisted as part of an upcoming test series to ensure each structure can withstand the incredible stresses of launch. The LVSA joins the core stage simulator, which was loaded into the test stand Sept. 21. The other three qualification articles and the Orion simulator will complete the stack later this fall. Testing is scheduled to begin in early 2017. SLS will be the world’s most powerful rocket, and with the Orion spacecraft, take astronauts to deep-space destinations, including the Journey to Mars. More information on the upcoming test series can be found here: http://go.nasa.gov/2dS8yXB

Efficacy of combining flexible and rigid ureteroscopy for transurethral lithotripsy.

PubMed

Shigemura, Katsumi; Yasufuku, Tomihiko; Yamashita, Masuo; Arakawa, Soichi; Fujisawa, Masato

2010-08-23

Transurethral lithotripsy (TUL) is a common procedure in urology. However, controversy persists about how to deal with stones pushed up into kidney from the ureter during the procedure of TUL. This study investigated the efficacy of combining flexible ureteroscopy and rigid ureteroscopy for pushed-up stones into kidney during TUL. Fotry-one patients underwent TUL by a single surgeon from July 2007 to May 2009. Eight cases resulted in pushed-up stones during operation or involved existing kidney stones. We used a Zero-tip or Litho Catch Basket catheter and a flexible ureteroscope to carry these stones in kidney down into the ureter where the rigid ureteroscope could then reach and handle the stone for lithotripsy or being taken away. A Lithoclast system was used for lithotripsy. Five cases involved stones pushed up during surgery and 3 cases involved stones already in the kidney in detail. We pulled the stones down into the ureter in all cases and successfully completed lithotripsy or removed the stone, thus avoiding the performance of additional extracorporeal shock wave lithotripsy (ESWL). In conclusions, combined use of flexible ureteroscopy and rigid ureteroscopy for upper urinary tract stones pushed up into the kidney during TUL or renal stones could be useful for avoiding additional ESWL.

A miniature cable-driven robot for crawling on the heart.

PubMed

Patronik, N A; Zenati, M A; Riviere, C N

2005-01-01

This document describes the design and preliminary testing of a cable-driven robot for the purpose of traveling on the surface of the beating heart to administer therapy. This methodology obviates mechanical stabilization and lung deflation, which are typically required during minimally invasive cardiac surgery. Previous versions of the robot have been remotely actuated through push-pull wires, while visual feedback was provided by fiber optic transmission. Although these early models were able to perform locomotion in vivo on porcine hearts, the stiffness of the wire-driven transmission and fiber optic camera limited the mobility of the robots. The new prototype described in this document is actuated by two antagonistic cable pairs, and contains a color CCD camera located in the front section of the device. These modifications have resulted in superior mobility and visual feedback. The cable-driven prototype has successfully demonstrated prehension, locomotion, and tissue dye injection during in vitro testing with a poultry model.

Aerial View: SLS Intertank Arrives at Marshall for Critical Structural Testing

NASA Image and Video Library

2018-03-08

A structural test version of the intertank for NASA's new deep-space rocket, the Space Launch System, arrives at NASA’s Marshall Space Flight Center in Huntsville, Alabama, March 4, aboard the barge Pegasus. The intertank is the second piece of structural hardware for the massive SLS core stage built at NASA's Michoud Assembly Facility in New Orleans delivered to Marshall for testing. The structural test article will undergo critical testing as engineers push, pull and bend the hardware with millions of pounds of force to ensure it can withstand the forces of launch and ascent. The test hardware is structurally identical to the flight version of the intertank that will connect the core stage's two colossal propellant tanks, serve as the upper-connection point for the two solid rocket boosters and house critical avionics and electronics. Pegasus, originally used during the Space Shuttle Program, has been redesigned and extended to accommodate the SLS rocket's massive, 212-foot-long core stage -- the backbone of the rocket. The 310-foot-long barge will ferry the flight core stage from Michoud to other NASA centers for tests and launch.

Routes and Reasons Out, Paths Back: The Influence of Push and Pull Reasons for Leaving School on Students' School Reengagement

ERIC Educational Resources Information Center

Boylan, Rebecca L.; Renzulli, Linda

2017-01-01

Dropout is a major issue facing our country's schools; however, many students who drop out of school later go on to finish their degree either by returning to high school or by earning a General Education Development (GED) credential. Despite this, there has been relatively little research on these students who "stopout" of high school.…

A Gene Pushes Some Men Away from College, but Social Support Pulls Them in

ERIC Educational Resources Information Center

Glenn, David

2009-01-01

This article reports that a new study has found that young men are less likely to attend college if they carry a common form of a gene associated with poor impulse control. The study also found that a strong environment--a high-quality high school and heavily involved parents--can counteract that genetic risk. For boys with this gene who grow up…

Advanced Multi-Photon Chromophores for Broad-Band Ultra-Fast Optical Limiting

DTIC Science & Technology

2014-11-04

for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data ...sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this...with expanded -system. This data provides crucial insight into the push-pull 2PA-enhancement mechanism. Following systems were studied in detail: i

Migration: An Old Scene with a New Cast. Center for Rural Manpower & Public Affairs Special Paper No. 23.

ERIC Educational Resources Information Center

Reul, Myrtle R.

Migration is not a new concept. All through America's history, there has been a push and pull related to population movement. Most Americans have moved several times and from one geographical region to another. Others have moved only a short distance from their birthplace or perhaps not at all. U.S. census information shows that each year nearly…

From Push to Pull: Barriers to MALSP Modernization

DTIC Science & Technology

2013-02-19

for the Japanese business model Kaizen . According to Hudgik (n.d.), “ Kaizen was created in Japan following World War II. The word Kaizen means... Kaizen business model seeks to maximize efficiencies of the manufacturer or company and challenge personnel to identify ways to increase productivity and...What is kaizen ? Retrieved from http://www.graphicproducts.com/tutorials/ kaizen /index.php Jabin, J. M. (2009, June 1). Evaluating alternative

Hedgerow Prominence

NASA Image and Video Library

2017-05-30

A solar prominence at the sun's edge put on quite a display of plasma being pushed and pulled by unstable magnetic fields (May 22-24, 2017). We call them hedgerow prominences because they look somewhat like a hedge of bushes. This is one of the better examples of this type of solar phenomenon than any we have seen in quite some time. Movies are available at https://photojournal.jpl.nasa.gov/catalog/PIA21650

[Unconventional hemodiafiltration: double-high-flux and push-pull].

PubMed

Lentini, Paolo; Pellanda, Valentina; Contestabile, Andrea; Berlingo, Graziella; de Cal, Massimo; Ronco, Claudio; Dell'Aquila, Roberto

2012-01-01

Growing evidence demonstrates that morbidity and mortality in patients with end-stage renal disease correlate significantly with retention of larger uremic toxins including β2 microglobulin. Even when hemodialysis is performed, complications such as dialysis-associated amyloidosis are likely to develop. These complications seem to be related to the retention and accumulation of larger uremic substances, only a small amount of which are removed by hemodialysis. On-line hemodiafiltration (OL-HDF) is popular but expensive; double-highflux hemodiafiltration (DHF-HDF) and push-pull hemodiafiltration (PP-HDF), special types of HDF, are very efficient treatments without the need for ultrapure substitution fluid. In DHF-HDF two high-flux dialyzers are connected in series by blood and dialysate lines. In the first dialyzer mixed diffusion convection removes fluid and solutes; in the second dialyzer backfiltration of sterile dialysate occurs, resembling the post-dilution OL-HDF mode. The PP-HDF method alternates rapid convection of body fluids and rapid backfiltration of sterile pyrogen-free dialysate using a high-flux membrane and a double-pump system. These treatments require an elevated blood flow and have the advantage that they use dialysis fluid instead of ultrapure fluid. Several studies have shown an elevated removal rate of middle molecules and reduction of dialysis-related amyloidosis symptoms like back and shoulder pain, restless leg syndrome, and carpal tunnel syndrome.

On push-forward representations in the standard gyrokinetic model

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

Miyato, N., E-mail: miyato.naoaki@jaea.go.jp; Yagi, M.; Scott, B. D.

2015-01-15

Two representations of fluid moments in terms of a gyro-center distribution function and gyro-center coordinates, which are called push-forward representations, are compared in the standard electrostatic gyrokinetic model. In the representation conventionally used to derive the gyrokinetic Poisson equation, the pull-back transformation of the gyro-center distribution function contains effects of the gyro-center transformation and therefore electrostatic potential fluctuations, which is described by the Poisson brackets between the distribution function and scalar functions generating the gyro-center transformation. Usually, only the lowest order solution of the generating function at first order is considered to explicitly derive the gyrokinetic Poisson equation. This ismore » true in explicitly deriving representations of scalar fluid moments with polarization terms. One also recovers the particle diamagnetic flux at this order because it is associated with the guiding-center transformation. However, higher-order solutions are needed to derive finite Larmor radius terms of particle flux including the polarization drift flux from the conventional representation. On the other hand, the lowest order solution is sufficient for the other representation, in which the gyro-center transformation part is combined with the guiding-center one and the pull-back transformation of the distribution function does not appear.« less

Loads produced by a suited subject performing tool tasks without the use of foot restraints

NASA Technical Reports Server (NTRS)

Rajulu, Sudhakar L.; Poliner, Jeffrey; Klute, Glenn K.

1993-01-01

With an increase in the frequency of extravehicular activities (EVA's) aboard the Space Shuttle, NASA is interested in determining the capabilities of suited astronauts while performing manual tasks during an EVA, in particular the situations in which portable foot restraints are not used to stabilize the astronauts. Efforts were made to document the forces that are transmitted to spacecraft while pushing and pulling an object as well as while operating a standard wrench and an automatic power tool. The six subjects studied aboard the KC-135 reduced gravity aircraft were asked to exert a maximum torque and to maintain a constant level of torque with a wrench, to push and pull an EVA handrail, and to operate a Hubble Space Telescope (HST) power tool. The results give an estimate of the forces and moments that an operator will transmit to the handrail as well as to the supporting structure. In general, it was more effective to use the tool inwardly toward the body rather than away from the body. There were no differences in terms of strength capabilities between right and left hands. The power tool was difficult to use. It is suggested that ergonomic redesigning of the power tool may increase the efficiency of power tool use.

Bright and photostable push-pull pyrene dye visualizes lipid order variation between plasma and intracellular membranes.

PubMed

Niko, Yosuke; Didier, Pascal; Mely, Yves; Konishi, Gen-ichi; Klymchenko, Andrey S

2016-01-11

Imaging lipid organization in cell membranes requires advanced fluorescent probes. Here, we show that a recently synthesized push-pull pyrene (PA), similarly to popular probe Laurdan, changes the emission maximum as a function of lipid order, but outperforms it by spectroscopic properties. In addition to red-shifted absorption compatible with common 405 nm diode laser, PA shows higher brightness and much higher photostability than Laurdan in apolar membrane environments. Moreover, PA is compatible with two-photon excitation at wavelengths >800 nm, which was successfully used for ratiometric imaging of coexisting liquid ordered and disordered phases in giant unilamellar vesicles. Fluorescence confocal microscopy in Hela cells revealed that PA efficiently stains the plasma membrane and the intracellular membranes at >20-fold lower concentrations, as compared to Laurdan. Finally, ratiometric imaging using PA reveals variation of lipid order within different cellular compartments: plasma membranes are close to liquid ordered phase of model membranes composed of sphingomyelin and cholesterol, while intracellular membranes are much less ordered, matching well membranes composed of unsaturated phospholipids without cholesterol. These differences in the lipid order were confirmed by fluorescence lifetime imaging (FLIM) at the blue edge of PA emission band. PA probe constitutes thus a new powerful tool for biomembrane research.

Research and Development for an Alternative RF Source Using Magnetrons in CEBAF

NASA Astrophysics Data System (ADS)

Jacobs, Andrew

2016-09-01

At Jefferson Lab, klystrons are currently used as a radiofrequency (RF) power source for the 1497 MHz Continuous Electron Beam Accelerator Facility (CEBAF) Continuous Wave (CW) system. A drop-in replacement for the klystrons in the form of a system of magnetrons is being developed. The klystron DC-RF efficiency at CEBAF is 35-51% while the estimated magnetron efficiency is 80-90%. Thus, the introduction of magnetrons to CEBAF will have enormous benefits in terms of electrical power saving. The primary focus of this project was to characterize a magnetron's frequency pushing and pulling curves at 2.45 GHz with stub tuner and anode current adjustments so that a Low Level RF controller for a new 1.497 GHz magnetron can be built. A Virtual Instrument was created in LabVIEW, and data was taken. The resulting data allowed for the creation of many constant lines of frequency and output power. Additionally, the results provided a characterization of magnetron oven temperature drift over the operation time and the relationship between anode current and frequency. Using these results, the control model of different variables and their feedback or feedforward that affect the frequency pushing and pulling of the magnetron is better developed. Department of Energy, Science Undergraduate Laboratory Internships, and Jefferson Lab.

Optical and Photovoltaic Properties of Thieno[3,2-b]thiophene-Based Push-Pull Organic Dyes with Different Anchoring Groups for Dye-Sensitized Solar Cells.

PubMed

Fernandes, Sara S M; Castro, M Cidália R; Pereira, Ana Isabel; Mendes, Adélio; Serpa, Carlos; Pina, João; Justino, Licínia L G; Burrows, Hugh D; Raposo, M Manuela M

2017-12-31

The effect of anchoring groups on the optical and electrochemical properties of triphenylamine-thienothiophenes, and on the photovoltaic performance of DSSCs photosensitized with the prepared dyes, was studied using newly synthesized compounds with cyanoacetic acid or rhodanine-3-acetic acid groups. Precursor aldehydes were synthesized through Suzuki cross-coupling, whereas Knoevenagel condensation of these with 2-cyanoacetic acid or rhodanine-3-acetic acid afforded the final push-pull dyes. A comprehensive photophysical study was performed in solution and in the solid state. The femtosecond time-resolved transient absorption spectra for the synthesized dyes were obtained following photoexcitation in solution and for the dyes adsorbed to TiO 2 mesoporous films. Information on conformation, electronic structure, and electron distribution was obtained by density functional theory (DFT) and time-dependent DFT calculations. Triphenylamine-thienothiophene functionalized with a cyanoacetic acid anchoring group displayed the highest conversion efficiency (3.68%) as the dye sensitizer in nanocrystalline TiO 2 solar cells. Coadsorption studies were performed for this dye with the ruthenium-based N719 dye, and they showed dye power conversion efficiencies enhanced by 20-64%. The best cell performance obtained with the coadsorbed N719 and cyanoacetic dye showed an efficiency of 6.05%.

Precision Sensing by Two Opposing Gradient Sensors: How Does Escherichia coli Find its Preferred pH Level?

PubMed Central

Hu, Bo; Tu, Yuhai

2013-01-01

It is essential for bacteria to find optimal conditions for their growth and survival. The optimal levels of certain environmental factors (such as pH and temperature) often correspond to some intermediate points of the respective gradients. This requires the ability of bacteria to navigate from both directions toward the optimum location and is distinct from the conventional unidirectional chemotactic strategy. Remarkably, Escherichia coli cells can perform such a precision sensing task in pH taxis by using the same chemotaxis machinery, but with opposite pH responses from two different chemoreceptors (Tar and Tsr). To understand bacterial pH sensing, we developed an Ising-type model for a mixed cluster of opposing receptors based on the push-pull mechanism. Our model can quantitatively explain experimental observations in pH taxis for various mutants and wild-type cells. We show how the preferred pH level depends on the relative abundance of the competing sensors and how the sensory activity regulates the behavioral response. Our model allows us to make quantitative predictions on signal integration of pH and chemoattractant stimuli. Our study reveals two general conditions and a robust push-pull scheme for precision sensing, which should be applicable in other adaptive sensory systems with opposing gradient sensors. PMID:23823247

Femtosecond Fluorescence Upconversion Study of a Naphthalimide-Bithiophene-Triphenylamine Push-Pull Dye in Solution.

PubMed

Maffeis, Valentin; Brisse, Romain; Labet, Vanessa; Jousselme, Bruno; Gustavsson, Thomas

2018-06-13

There is a high interest in the development of new push-pull dyes for the use in dye sensitized solar cells. The pronounced charge transfer character of the directly photoexcited state is in principle favorable for a charge injection. Here, we report a time-resolved fluorescence study of a triphenylamine-bithiophene-naphthalimide dye in four solvents of varying polarity using fluorescence upconversion. The recording of femtosecond time-resolved fluorescence spectra corrected for the group velocity dispersion allows for a detailed analysis discriminating between spectral shifts and total intensity decays. After photoexcitation, the directly populated state (S 1 /FC) evolves toward a relaxed charge transfer state (S 1 /CT). This S 1 /CT state is characterized by a lower radiative transition moment and a higher nonradiative quenching. The fast dynamic shift of the fluorescence band is well described by solvation dynamics in polar solvents, but less so in nonpolar solvents, hinting that the excited-state relaxation process occurs on a free energy surface whose topology is strongly governed by the solvent polarity. This study underlines the influence of the environment on the intramolecular charge transfer (ICT) process, and the necessity to analyze time-resolved data in detail when solvation and ICT occur simultaneously.

Characterization of SiC (SCS-6) Fiber Reinforced Reaction-Formed Silicon Carbide Matrix Composites

NASA Technical Reports Server (NTRS)

Singh, Mrityunjay; Dickerson, Robert M.

1995-01-01

Silicon carbide (SCS-6) fiber reinforced-reaction formed silicon carbide matrix composites were fabricated using NASA's reaction forming process. Silicon-2 at a percent of niobium alloy was used as an infiltrant instead of pure silicon to reduce the amount of free silicon in the matrix after reaction forming. The matrix primarily consists of silicon carbide with a bi-modal grain size distribution. Minority phases dispersed within the matrix are niobium disilicide (NbSi2), carbon and silicon. Fiber push-out tests on these composites determined a debond stress of approx. 67 MPa and a frictional stress of approx. 60 MPa. A typical four point flexural strength of the composite is 297 MPa (43.1 KSi). This composite shows tough behavior through fiber pull out.

Casingless down-hole for sealing an ablation volume and obtaining a sample for analysis

DOEpatents

Noble, D.T.; Braymen, S.D.; Anderson, M.S.

1996-10-01

A casing-less down hole sampling system for acquiring a subsurface sample for analysis using an inductively coupled plasma system is disclosed. The system includes a probe which is pushed into the formation to be analyzed using a hydraulic ram system. The probe includes a detachable tip member which has a soil point and a barb, with the soil point aiding the penetration of the earth, and the barb causing the tip member to disengage from the probe and remain in the formation when the probe is pulled up. The probe is forced into the formation to be tested, and then pulled up slightly, to disengage the tip member and expose a column of the subsurface formation to be tested. An instrumentation tube mounted in the probe is then extended outward from the probe to longitudinally extend into the exposed column. A balloon seal mounted on the end of the instrumentation tube allows the bottom of the column to be sealed. A source of laser radiation is emitted from the instrumentation tube to ablate a sample from the exposed column. The instrumentation tube can be rotated in the probe to sweep the laser source across the surface of the exposed column. An aerosol transport system carries the ablated sample from the probe to the surface for testing in an inductively coupled plasma system. By testing at various levels in the down-hole as the probe is extracted from the soil, a profile of the subsurface formation may be obtained. 9 figs.

In situ mobility of uranium in the presence of nitrate following sulfate-reducing conditions.

PubMed

Paradis, Charles J; Jagadamma, Sindhu; Watson, David B; McKay, Larry D; Hazen, Terry C; Park, Melora; Istok, Jonathan D

2016-04-01

Reoxidation and mobilization of previously reduced and immobilized uranium by dissolved-phase oxidants poses a significant challenge for remediating uranium-contaminated groundwater. Preferential oxidation of reduced sulfur-bearing species, as opposed to reduced uranium-bearing species, has been demonstrated to limit the mobility of uranium at the laboratory scale yet field-scale investigations are lacking. In this study, the mobility of uranium in the presence of nitrate oxidant was investigated in a shallow groundwater system after establishing conditions conducive to uranium reduction and the formation of reduced sulfur-bearing species. A series of three injections of groundwater (200 L) containing U(VI) (5 μM) and amended with ethanol (40 mM) and sulfate (20 mM) were conducted in ten test wells in order to stimulate microbial-mediated reduction of uranium and the formation of reduced sulfur-bearing species. Simultaneous push-pull tests were then conducted in triplicate well clusters to investigate the mobility of U(VI) under three conditions: 1) high nitrate (120 mM), 2) high nitrate (120 mM) with ethanol (30 mM), and 3) low nitrate (2 mM) with ethanol (30 mM). Dilution-adjusted breakthrough curves of ethanol, nitrate, nitrite, sulfate, and U(VI) suggested that nitrate reduction was predominantly coupled to the oxidation of reduced-sulfur bearing species, as opposed to the reoxidation of U(IV), under all three conditions for the duration of the 36-day tests. The amount of sulfate, but not U(VI), recovered during the push-pull tests was substantially more than injected, relative to bromide tracer, under all three conditions and further suggested that reduced sulfur-bearing species were preferentially oxidized under nitrate-reducing conditions. However, some reoxidation of U(IV) was observed under nitrate-reducing conditions and in the absence of detectable nitrate and/or nitrite. This suggested that reduced sulfur-bearing species may not be fully effective at limiting the mobility of uranium in the presence of dissolved and/or solid-phase oxidants. The results of this field study confirmed those of previous laboratory studies which suggested that reoxidation of uranium under nitrate-reducing conditions can be substantially limited by preferential oxidation of reduced sulfur-bearing species. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

In situ mobility of uranium in the presence of nitrate following sulfate-reducing conditions

DOE PAGES

Paradis, Charles J.; Jagadamma, Sindhu; Watson, David B.; ...

2016-02-11

Reoxidation and mobilization of previously reduced and immobilized uranium by dissolved phase oxidants poses a significant challenge for remediating uranium-contaminated groundwater. Preferential oxidation of reduced sulfur-bearing species, as opposed to reduced uranium bearing species, has been demonstrated to limit the mobility of uranium at the laboratory scale yet field-scale investigations are lacking. Here in this study, the mobility of uranium in the presence of nitrate oxidant was investigated in a shallow groundwater system after establishing conditions conducive to uranium reduction and the formation of reduced sulfur-bearing species. A series of three injections of groundwater (200 L) containing U(VI) (5 μM)more » and amended with ethanol (40 mM) and sulfate (20 mM) were conducted in ten test wells in order to stimulate microbial mediated reduction of uranium and the formation of reduced sulfur-bearing species. Simultaneous push-pull tests were then conducted in triplicate well clusters to investigate the mobility of U(VI) under three conditions: 1) high nitrate (120 mM), 2) high nitrate (120 mM) with ethanol (30 mM), and 3) low nitrate (2 mM) with ethanol (30 mM). Dilution-adjusted breakthrough curves of ethanol, nitrate, nitrite, sulfate, and U(VI) suggested that nitrate reduction was predominantly coupled to the oxidation of reduced-sulfur bearing species, as opposed to the reoxidation of U(IV), under all three conditions for the duration of the 36-day tests. The amount of sulfate, but not U(VI), recovered during the push-pull tests was substantially more than injected, relative to bromide tracer, under all three conditions and further suggested that reduced sulfur-bearing species were preferentially oxidized under nitrate-reducing conditions. However, some reoxidation of U(IV) was observed under nitrate-reducing conditions and in the absence of detectable nitrate and/or nitrite. This suggested that reduced sulfur-bearing species may not be fully effective at limiting the mobility of uranium in the presence of dissolved and/or solid-phase oxidants. Lastly, the results of this field study confirmed those of previous laboratory studies which suggested that reoxidation of uranium under nitrate-reducing conditions can be substantially limited by preferential oxidation of reduced sulfur-bearing species.« less

Determinants of the Egyptian labour migration.

PubMed

Kandil, M; Metwally, M

1992-03-01

The objective is to summarize the pattern of Egyptian migration to Arab oil-producing countries (AOPC), to review some factors that are important determinants of labor movement based on theory, and to empirically model the migration rate to AOPC and to Saudi Arabia. Factors are differentiated as to their relative importance. Push factors are the low wages, high inflation rate, and high population density in Egypt; pull factors are higher wages. It is predicted that an increase in income from destination countries has a significant positive impact on the migration rate. An increase in population density stimulates migration. An increase in inflation acts to increase out-migration with a 2-year lag, which accommodates departure preparation. Egypt's experience with labor migration is described for the pre-oil boom, and the post-oil boom. Several estimates of labor migration are given. Government policy toward migration is positive. Theory postulates migration to be determined by differences in the availability of labor, labor rewards between destination and origin, and the cost of migration. In the empirical model, push factors are population density, the current inflation rate, and the ratio of income/capita in AOPC to Egypt. The results indicate that the ratio of income/capita had a strong pull impact and population density had a strong push impact. The inflation rate has a positive impact with a lag estimated at 2 years. Prior to the Camp David Accord, there was a significant decrease in the number of Egyptian migrants due to political tension. The findings support the classical theory of factor mobility. The consequences of migration on the Egyptian economy have been adverse. Future models should disaggregate data because chronic shortages exist in some parts of the labor market. Manpower needs assessment would be helpful for policy makers.

Light-Induced Pulling and Pushing by the Synergic Effect of Optical Force and Photophoretic Force

NASA Astrophysics Data System (ADS)

Lu, Jinsheng; Yang, Hangbo; Zhou, Lina; Yang, Yuanqing; Luo, Si; Li, Qiang; Qiu, Min

2017-01-01

Optical force, coming from momentum exchange during light-matter interactions, has been widely utilized to manipulate microscopic objects, though mostly in vacuum or in liquids. By contrast, due to the light-induced thermal effect, photophoretic force provides an alternative and effective way to transport light-absorbing particles in ambient gases. However, in most cases these forces work independently. Here, by employing the synergy of optical force and photophoretic force, we propose and experimentally demonstrate a configuration which can drive a micron-size metallic plate moving back and forth on a tapered fiber with supercontinuum light in ambient air. Optical pulling and oscillation of the metallic plate are experimentally realized. The results might open exhilarating possibilities in applications of optical driving and energy conversion.

Drawbar Pull

DTIC Science & Technology

2017-01-26

Includes procedures for hard surface, soil , and water tests. Discusses vehicle preparation, instrumentation method of computing results, data reduction...and amphibious vehicles. 15. SUBJECT TERMS Bollard pull Soft- soil mobility Drawbar pull Vehicle, amphibious Drawbar horsepower Vehicle...4.3 Drawbar Pull in Soft Soil ................................................. 8 4.4 Amphibious Vehicle Tests (Drawbar Pull in Water and Bollard Pull

Smart Push, Smart Pull, Sensor to Shooter in a Multi-Level Secure/Safe (MLS) Infrastructure

DTIC Science & Technology

2006-05-04

policy violation with respect to: Security Safety Financial Posture Infrastructure The IATF identifies five levels: V1: Negligible effect V2: Minimal...MLS) Infrastructure Step 2: Determine Threat Levels Best practices also in the IATF Threats are ranked by assessing: Capability Resources Motivation...Risk Willingness The IATF identifies seven levels: T1: Inadvertent or accidental events Tripping over a power cord T2: Minimal resources – willing to

Urban Land Use by Illegal Armed Groups in Medellin

DTIC Science & Technology

2011-10-17

Medellín, in Colombia‘s northwest, is surrounded by one of Colombia‘s most densely populated rural areas, but itself sets at a disproportionately greater...of labor opportunity. Those who migrated to the city, whether they compelled or not, did not necessarily find a peaceful alternative to their rural ...Especially while rural violence pushed, and illicit money pulled people to the city, smaller areas of terrain within the metropolitan area became

4D-π-1A type β-substituted ZnII-porphyrins: ideal green sensitizers for building-integrated photovoltaics.

PubMed

Covezzi, A; Orbelli Biroli, A; Tessore, F; Forni, A; Marinotto, D; Biagini, P; Di Carlo, G; Pizzotti, M

2016-10-18

Two novel green β-substituted Zn II -porphyrins, G1 and G2, based on a 4D-π-1A type substitution pattern have been synthesized. Their enhanced push-pull character, by reduction of H-L energy gaps, promotes broadening and red-shifting of absorption bands. The effective synthetic pathway and the remarkable spectroscopic properties make G2 ideal for BIPV application.

Close up view of switchboard panel operator's station #1; panel ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Close up view of switchboard panel operator's station #1; panel contains 1200 push-pull button switches which control poer to red, green, and white indicating lights on the model board; white lights indicate that power is off; green lights indicate that equipment (switch breaker or transformer) is off; red lights indicate that equipment is on - Thirtieth Street Station, Power Director Center, Thirtieth & Market Streets in Amtrak Railroad Station, Philadelphia, Philadelphia County, PA

Characterization and Performance Comparison of Low-Voltage, High-Speed, Push-Pull and Traveling-Wave Silicon Mach-Zehnder Modulators

DTIC Science & Technology

2014-03-27

2Fieeexplore.ieee.org%2Fxpls%2Fabs all.jsp%3Farnumber%3D5875447 [7] D. Marris- Morini , L. Vivien, G. Rasigade, J.-M. Fedeli, E. Cassan, X. Le Roux, P. Crozat...3rd ed., B. Zobrist, Ed. Wiley, 2002. [26] M. Ziebell, D. Marris- Morini , G. Rasigade, P. Crozat, J.-M. Fedeli, E. Cassan, and L. Vivien, “Low-loss and