Influence of "J"-Curve Spring Stiffness on Running Speeds of Segmented Legs during High-Speed Locomotion.

PubMed

Wang, Runxiao; Zhao, Wentao; Li, Shujun; Zhang, Shunqi

2016-01-01

Both the linear leg spring model and the two-segment leg model with constant spring stiffness have been broadly used as template models to investigate bouncing gaits for legged robots with compliant legs. In addition to these two models, the other stiffness leg spring models developed using inspiration from biological characteristic have the potential to improve high-speed running capacity of spring-legged robots. In this paper, we investigate the effects of "J"-curve spring stiffness inspired by biological materials on running speeds of segmented legs during high-speed locomotion. Mathematical formulation of the relationship between the virtual leg force and the virtual leg compression is established. When the SLIP model and the two-segment leg model with constant spring stiffness and with "J"-curve spring stiffness have the same dimensionless reference stiffness, the two-segment leg model with "J"-curve spring stiffness reveals that (1) both the largest tolerated range of running speeds and the tolerated maximum running speed are found and (2) at fast running speed from 25 to 40/92 m s -1 both the tolerated range of landing angle and the stability region are the largest. It is suggested that the two-segment leg model with "J"-curve spring stiffness is more advantageous for high-speed running compared with the SLIP model and with constant spring stiffness.

Influence of “J”-Curve Spring Stiffness on Running Speeds of Segmented Legs during High-Speed Locomotion

PubMed Central

2016-01-01

Both the linear leg spring model and the two-segment leg model with constant spring stiffness have been broadly used as template models to investigate bouncing gaits for legged robots with compliant legs. In addition to these two models, the other stiffness leg spring models developed using inspiration from biological characteristic have the potential to improve high-speed running capacity of spring-legged robots. In this paper, we investigate the effects of “J”-curve spring stiffness inspired by biological materials on running speeds of segmented legs during high-speed locomotion. Mathematical formulation of the relationship between the virtual leg force and the virtual leg compression is established. When the SLIP model and the two-segment leg model with constant spring stiffness and with “J”-curve spring stiffness have the same dimensionless reference stiffness, the two-segment leg model with “J”-curve spring stiffness reveals that (1) both the largest tolerated range of running speeds and the tolerated maximum running speed are found and (2) at fast running speed from 25 to 40/92 m s−1 both the tolerated range of landing angle and the stability region are the largest. It is suggested that the two-segment leg model with “J”-curve spring stiffness is more advantageous for high-speed running compared with the SLIP model and with constant spring stiffness. PMID:28018127

Accurate Calibration and Uncertainty Estimation of the Normal Spring Constant of Various AFM Cantilevers

PubMed Central

Song, Yunpeng; Wu, Sen; Xu, Linyan; Fu, Xing

2015-01-01

Measurement of force on a micro- or nano-Newton scale is important when exploring the mechanical properties of materials in the biophysics and nanomechanical fields. The atomic force microscope (AFM) is widely used in microforce measurement. The cantilever probe works as an AFM force sensor, and the spring constant of the cantilever is of great significance to the accuracy of the measurement results. This paper presents a normal spring constant calibration method with the combined use of an electromagnetic balance and a homemade AFM head. When the cantilever presses the balance, its deflection is detected through an optical lever integrated in the AFM head. Meanwhile, the corresponding bending force is recorded by the balance. Then the spring constant can be simply calculated using Hooke’s law. During the calibration, a feedback loop is applied to control the deflection of the cantilever. Errors that may affect the stability of the cantilever could be compensated rapidly. Five types of commercial cantilevers with different shapes, stiffness, and operating modes were chosen to evaluate the performance of our system. Based on the uncertainty analysis, the expanded relative standard uncertainties of the normal spring constant of most measured cantilevers are believed to be better than 2%. PMID:25763650

Determining the elastic properties of aptamer-ricin single molecule multiple pathway interactions

NASA Astrophysics Data System (ADS)

Wang, Bin; Park, Bosoon; Kwon, Yongkuk; Xu, Bingqian

2014-05-01

We report on the elastic properties of ricin and anti-ricin aptamer interactions, which showed three stable binding conformations, each of which has its special elastic properties. These different unbinding pathways were investigated by the dynamic force spectroscopy. A series-spring model combining the worm-like-chain model and Hook's law was used to estimate the apparent spring constants of the aptamer and linker molecule polyethylene glycol. The aptamer in its three different unbinding pathways showed different apparent spring constants. The two reaction barriers in the unbinding pathways also influence the apparent spring constant of the aptamer. This special elastic behavior of aptamer was used to distinguish its three unbinding pathways under different loading rates. This method also offered a way to distinguish and discard the non-specific interactions in single molecule experiments.

Note: Improved calibration of atomic force microscope cantilevers using multiple reference cantilevers.

PubMed

Sader, John E; Friend, James R

2015-05-01

Overall precision of the simplified calibration method in J. E. Sader et al., Rev. Sci. Instrum. 83, 103705 (2012), Sec. III D, is dominated by the spring constant of the reference cantilever. The question arises: How does one take measurements from multiple reference cantilevers, and combine these results, to improve uncertainty of the reference cantilever's spring constant and hence the overall precision of the method? This question is addressed in this note. Its answer enables manufacturers to specify of a single set of data for the spring constant, resonant frequency, and quality factor, from measurements on multiple reference cantilevers. With this data set, users can trivially calibrate cantilevers of the same type.

Experimental determination of micromachined discrete and continuous device spring constants using nanoindentation method

NASA Astrophysics Data System (ADS)

Chan, M. L.; Tay, Francis E.; Logeeswaran, V. J.; Zeng, Kaiyang; Shen, Lu; Chau, Fook S.

2002-04-01

A rapid and accurate static and quasi-static method for determining the out-of-plane spring constraints of cantilevers and a micromachined vibratory sensor is presented. In the past, much of the effort in nanoindentation application was to investigate the thin-film mechanical properties. In this paper, we have utilized the nanoindentation method to measure directly some micromachined device (e.g. microgyroscope) spring constants. The cantilevers and devices tested were fabricated using the MUMPS process and an SOI process (patent pending). Spring constants are determined using a commercial nanoindentation apparatus UMIS-2000 configured with both Berkovich and spherical indenter tip that can be placed onto the device with high accuracy. Typical load resolution is 20micrometers N to 0.5N and a displacement resolution of 0.05nm. Information was deduced from the penetration depth versus load curves during both loading and unloading.

Variable gas spring for matching power output from FPSE to load of refrigerant compressor

DOEpatents

Chen, Gong; Beale, William T.

1990-01-01

The power output of a free piston Stirling engine is matched to a gas compressor which it drives and its stroke amplitude is made relatively constant as a function of power by connecting a gas spring to the drive linkage from the engine to the compressor. The gas spring is connected to the compressor through a passageway in which a valve is interposed. The valve is linked to the drive linkage so it is opened when the stroke amplitude exceeds a selected limit. This allows compressed gas to enter the spring, increase its spring constant, thus opposing stroke increase and reducing the phase lead of the displacer ahead of the piston to reduce power output and match it to a reduced load power demand.

Variable gas spring for matching power output from FPSE to load of refrigerant compressor

DOEpatents

Chen, G.; Beale, W.T.

1990-04-03

The power output of a free piston Stirling engine is matched to a gas compressor which it drives and its stroke amplitude is made relatively constant as a function of power by connecting a gas spring to the drive linkage from the engine to the compressor. The gas spring is connected to the compressor through a passageway in which a valve is interposed. The valve is linked to the drive linkage so it is opened when the stroke amplitude exceeds a selected limit. This allows compressed gas to enter the spring, increase its spring constant, thus opposing stroke increase and reducing the phase lead of the displacer ahead of the piston to reduce power output and match it to a reduced load power demand. 6 figs.

Precise and direct method for the measurement of the torsion spring constant of the atomic force microscopy cantilevers

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

Jarząbek, D. M., E-mail: djarz@ippt.pan.pl

2015-01-15

A direct method for the evaluation of the torsional spring constants of the atomic force microscope cantilevers is presented in this paper. The method uses a nanoindenter to apply forces at the long axis of the cantilever and in the certain distance from it. The torque vs torsion relation is then evaluated by the comparison of the results of the indentations experiments at different positions on the cantilever. Next, this relation is used for the precise determination of the torsional spring constant of the cantilever. The statistical analysis shows that the standard deviation of the calibration measurements is equal tomore » approximately 1%. Furthermore, a simple method for calibration of the photodetector’s lateral response is proposed. The overall procedure of the lateral calibration constant determination has the accuracy approximately equal to 10%.« less

Note: Improved calibration of atomic force microscope cantilevers using multiple reference cantilevers

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

Sader, John E., E-mail: jsader@unimelb.edu.au; Friend, James R.

2015-05-15

Overall precision of the simplified calibration method in J. E. Sader et al., Rev. Sci. Instrum. 83, 103705 (2012), Sec. III D, is dominated by the spring constant of the reference cantilever. The question arises: How does one take measurements from multiple reference cantilevers, and combine these results, to improve uncertainty of the reference cantilever’s spring constant and hence the overall precision of the method? This question is addressed in this note. Its answer enables manufacturers to specify of a single set of data for the spring constant, resonant frequency, and quality factor, from measurements on multiple reference cantilevers. Withmore » this data set, users can trivially calibrate cantilevers of the same type.« less

Adaptive vibration suppression system: an iterative control law for a piezoelectric actuator shunted by a negative capacitor.

PubMed

Kodejska, Milos; Mokry, Pavel; Linhart, Vaclav; Vaclavik, Jan; Sluka, Tomas

2012-12-01

An adaptive system for the suppression of vibration transmission using a single piezoelectric actuator shunted by a negative capacitance circuit is presented. It is known that by using a negative-capacitance shunt, the spring constant of a piezoelectric actuator can be controlled to extreme values of zero or infinity. Because the value of spring constant controls a force transmitted through an elastic element, it is possible to achieve a reduction of transmissibility of vibrations through the use of a piezoelectric actuator by reducing its effective spring constant. Narrow frequency range and broad frequency range vibration isolation systems are analyzed, modeled, and experimentally investigated. The problem of high sensitivity of the vibration control system to varying operational conditions is resolved by applying an adaptive control to the circuit parameters of the negative capacitor. A control law that is based on the estimation of the value of the effective spring constant of a shunted piezoelectric actuator is presented. An adaptive system which achieves a self-adjustment of the negative capacitor parameters is presented. It is shown that such an arrangement allows the design of a simple electronic system which offers a great vibration isolation efficiency under variable vibration conditions.

Study of scratch drive actuator force characteristics

NASA Astrophysics Data System (ADS)

Li, Lijie; Brown, J. Gordon; Uttamchandani, Deepak

2002-11-01

Microactuators are one of the key components in MEMS technology, and various designs have been realized through different fabrication processes. One type of microactuator commonly used is the scratch drive actuator (SDA) that is frequently fabricated by surface micromachining processes. An experimental investigation has been conducted on the force characteristics of SDAs fabricated using the JDSU Microsystems MUMPs process. One-, two-, three- and four-plate SDAs connected to box-springs have been designed and fabricated for these experiments using MUMPs run 44. The spring constant for the box-springs has been calculated by FEM using ANSYS software. The product of the spring constant and spring extension is used to measure the forces produced by these SDAs. It is estimated that the forces produced exceed 250 μN from a one-plate SDA and 850 μN from a four-plate SDA.

Effects of mucosal loading on vocal fold vibration.

PubMed

Tao, Chao; Jiang, Jack J

2009-06-01

A chain model was proposed in this study to examine the effects of mucosal loading on vocal fold vibration. Mucosal loading was defined as the loading caused by the interaction between the vocal folds and the surrounding tissue. In the proposed model, the vocal folds and the surrounding tissue were represented by a series of oscillators connected by a coupling spring. The lumped masses, springs, and dampers of the oscillators modeled the tissue properties of mass, stiffness, and viscosity, respectively. The coupling spring exemplified the tissue interactions. By numerically solving this chain model, the effects of mucosal loading on the phonation threshold pressure, phonation instability pressure, and energy distribution in a voice production system were studied. It was found that when mucosal loading is small, phonation threshold pressure increases with the damping constant R(r), the mass constant R(m), and the coupling constant R(mu) of mucosal loading but decreases with the stiffness constant R(k). Phonation instability pressure is also related to mucosal loading. It was found that phonation instability pressure increases with the coupling constant R(mu) but decreases with the stiffness constant R(k) of mucosal loading. Therefore, it was concluded that mucosal loading directly affects voice production.

Effects of mucosal loading on vocal fold vibration

NASA Astrophysics Data System (ADS)

Tao, Chao; Jiang, Jack J.

2009-06-01

A chain model was proposed in this study to examine the effects of mucosal loading on vocal fold vibration. Mucosal loading was defined as the loading caused by the interaction between the vocal folds and the surrounding tissue. In the proposed model, the vocal folds and the surrounding tissue were represented by a series of oscillators connected by a coupling spring. The lumped masses, springs, and dampers of the oscillators modeled the tissue properties of mass, stiffness, and viscosity, respectively. The coupling spring exemplified the tissue interactions. By numerically solving this chain model, the effects of mucosal loading on the phonation threshold pressure, phonation instability pressure, and energy distribution in a voice production system were studied. It was found that when mucosal loading is small, phonation threshold pressure increases with the damping constant Rr, the mass constant Rm, and the coupling constant Rμ of mucosal loading but decreases with the stiffness constant Rk. Phonation instability pressure is also related to mucosal loading. It was found that phonation instability pressure increases with the coupling constant Rμ but decreases with the stiffness constant Rk of mucosal loading. Therefore, it was concluded that mucosal loading directly affects voice production.

The Influence of Spring Length on the Physical Parameters of Simple Harmonic Motion

ERIC Educational Resources Information Center

Triana, C. A.; Fajardo, F.

2012-01-01

The aim of this work is to analyse the influence of spring length on the simple harmonic motion of a spring-mass system. In particular, we study the effect of changing the spring length on the elastic constant "[kappa]", the angular frequency "[omega]" and the damping factor "[gamma]" of the oscillations. To characterize the behaviour of these…

50 CFR 92.30 - General overview of regulations.

Code of Federal Regulations, 2013 CFR

2013-10-01

... Governing Subsistence Harvest § 92.30 General overview of regulations. These regulations establish a spring... hunting regulations in the Federal Register in the spring for seasons beginning September 1 of that year... 92.39 provide for the annual harvest of migratory birds and their eggs during spring and summer for...

50 CFR 92.30 - General overview of regulations.

Code of Federal Regulations, 2014 CFR

2014-10-01

... Governing Subsistence Harvest § 92.30 General overview of regulations. These regulations establish a spring... hunting regulations in the Federal Register in the spring for seasons beginning September 1 of that year... 92.39 provide for the annual harvest of migratory birds and their eggs during spring and summer for...

NiTi Alloy Negator Springs for Long-Stroke Constant-Force Shape Memory Actuators: Modeling, Simulation and Testing

NASA Astrophysics Data System (ADS)

Spaggiari, Andrea; Dragoni, Eugenio; Tuissi, Ausonio

2014-07-01

This work aims at the experimental characterization and modeling validation of shape memory alloy (SMA) Negator springs. According to the classic engineering books on springs, a Negator spring is a spiral spring made of strip of metal wound on the flat with an inherent curvature such that, in repose, each coil wraps tightly on its inner neighbor. The main feature of a Negator springs is the nearly constant force displacement behavior in the unwinding of the strip. Moreover the stroke is very long, theoretically infinite, as it depends only on the length of the initial strip. A Negator spring made in SMA is built and experimentally tested to demonstrate the feasibility of this actuator. The shape memory Negator spring behavior can be modeled with an analytical procedure, which is in good agreement with the experimental test and can be used for design purposes. In both cases, the material is modeled as elastic in austenitic range, while an exponential continuum law is used to describe the martensitic behavior. The experimental results confirms the applicability of this kind of geometry to the shape memory alloy actuators, and the analytical model is confirmed to be a powerful design tool to dimension and predict the spring behavior both in martensitic and austenitic range.

Scalability of an endoluminal spring for distraction enterogenesis.

PubMed

Rouch, Joshua D; Huynh, Nhan; Scott, Andrew; Chiang, Elvin; Wu, Benjamin M; Shekherdimian, Shant; Dunn, James C Y

2016-12-01

Techniques of distraction enterogenesis have been explored to provide increased intestinal length to treat short bowel syndrome (SBS). Self-expanding, polycaprolactone (PCL) springs have been shown to lengthen bowel in small animal models. Their feasibility in larger animal models is a critical step before clinical use. Juvenile mini-Yucatan pigs underwent jejunal isolation or blind ending Roux-en-y jejunojejunostomy with insertion of either a PCL spring or a sham PCL tube. Extrapolated from our spring characteristics in rodents, proportional increases in spring constant and size were made for porcine intestine. Jejunal segments with 7mm springs with k between 9 and 15N/m demonstrated significantly increased lengthening in isolated segment and Roux-en-y models. Complications were noted in only two animals, both using high spring constant k>17N/m. Histologically, lengthened segments in the isolated and Roux models demonstrated significantly increased muscularis thickness and crypt depth. Restoration of lengthened, isolated segments back into continuity was technically feasible after 6weeks. Self-expanding, endoluminal PCL springs, which exert up to 0.6N force, safely achieve significant intestinal lengthening in a translatable, large-animal model. These spring characteristics may provide a scalable model for the treatment of SBS in children. Copyright © 2016 Elsevier Inc. All rights reserved.

Variable resistance constant tension and lubrication device. [using oil-saturated leather wiper

NASA Technical Reports Server (NTRS)

Smith, H. J. (Inventor)

1974-01-01

A variable resistance device is described which includes a cylindrical housing having elongated resistance wires. A movable arm having a supporting block carried on the outer end is rotatably carried by the cylindrical housing. An arcuate steel spring member is pivotally supported by the movable arm. A leather wiper member is carried adjacent to one end of the spring steel member, and an electrically conductive surface is carried adjacent to the other end. The supporting block maintains the spring steel member in compression so that a constant pressure is applied to the conductive end of the spring steel member and the leather wiper. The leather wiper is saturated with a lubricating oil for maintaining the resistance wire clean as the movable arm is manipulated.

Experimenting with Inexpensive Plastic Springs

ERIC Educational Resources Information Center

Perez, Leander; Marques, Adriana; Sánchez, Iván

2014-01-01

Acommon undergraduate laboratory experience is the determination of the elastic constant of a spring, whether studying the elongation under a static load or studying the damped harmonic motion of the spring with a suspended mass. An alternative approach to this laboratory experience has been suggested by Menezes et al., aimed at studying the…

Apparatus for Teaching Physics: Linearizing a Nonlinear Spring.

ERIC Educational Resources Information Center

Wagner, Glenn

1995-01-01

Describes a method to eliminate the nonlinearity from a spring that is used in experimental verification of Hooke's Law where students are asked to determine the force constant and the linear equation that describes the extension of the spring as a function of the mass placed on it. (JRH)

Compartmentalized storage tank for electrochemical cell system

NASA Technical Reports Server (NTRS)

Piecuch, Benjamin Michael (Inventor); Dalton, Luke Thomas (Inventor)

2010-01-01

A compartmentalized storage tank is disclosed. The compartmentalized storage tank includes a housing, a first fluid storage section disposed within the housing, a second fluid storage section disposed within the housing, the first and second fluid storage sections being separated by a movable divider, and a constant force spring. The constant force spring is disposed between the housing and the movable divider to exert a constant force on the movable divider to cause a pressure P1 in the first fluid storage section to be greater than a pressure P2 in the second fluid storage section, thereby defining a pressure differential.

Nonharmonic oscillations of nanosized cantilevers due to quantum-size effects

NASA Astrophysics Data System (ADS)

Olsen, Martin; Gradin, Per; Lindefelt, Ulf; Olin, Håkan

2010-02-01

Using a one-dimensional jellium model and standard beam theory we calculate the spring constant of a vibrating nanowire cantilever. By using the asymptotic energy eigenvalues of the standing electron waves over the nanometer-sized cross-section area, the change in the grand canonical potential is calculated and hence the force and the spring constant. As the wire is bent more electron states fits in its cross section. This has an impact on the spring “constant” which oscillates slightly with the bending of the wire. In this way we obtain an amplitude-dependent resonance frequency of the oscillations that should be detectable.

Apparatus measures swelling of membranes in electrochemical cells

NASA Technical Reports Server (NTRS)

Hennigan, T. J.

1965-01-01

Apparatus consisting of a pressure plate unit, four springs of known spring constant and a micrometer measures the swelling and force exerted by the polymer membranes of alkaline electrochemical cells.

Biomechanical analysis of cervical distraction.

PubMed

Miller, L S; Cotler, H B; De Lucia, F A; Cotler, J M; Hume, E L

1987-11-01

A biomechanical analysis of cervical distraction is presented, and a model comparing closed reduction of cervical spine dislocations to spring mechanics is developed. Behavior of a spring may be described as F = k delta x where F = distraction force; delta x = elongation of the spring; and k = spring constant. The records and roentgenograms of 24 cervical spine dislocations were reviewed retrospectively. Evaluation of cervical distraction vs traction weight indicates that Ftraction = kneck delta x; where F = traction weight and x = distraction at the injured level. The constant, kneck, is different for bilateral and unilateral dislocations (P less than .001) and is a function of magnitude of injury and neck morphology. As determined in this study, traction weight needed for reduction of facet dislocations may be estimated using the formulae: Ftx = 107.1 lbs/cm (x) unilateral, and Ftx = 76.4 lbs/cm (x) bilateral.

Elongation measurement using 1-dimensional image correlation method

NASA Astrophysics Data System (ADS)

Phongwisit, Phachara; Kamoldilok, Surachart; Buranasiri, Prathan

2016-11-01

Aim of this paper was to study, setup, and calibrate an elongation measurement by using 1- Dimensional Image Correlation method (1-DIC). To confirm our method and setup correctness, we need calibration with other methods. In this paper, we used a small spring as a sample to find a result in terms of spring constant. With a fundamental of Image Correlation method, images of formed and deformed samples were compared to understand the difference between deformed process. By comparing the location of reference point on both image's pixel, the spring's elongation were calculated. Then, the results have been compared with the spring constants, which were found from Hooke's law. The percentage of 5 percent error has been found. This DIC method, then, would be applied to measure the elongation of some different kinds of small fiber samples.

Cyanobacteria in Sulfidic Spring Microbial Mats Can Perform Oxygenic and Anoxygenic Photosynthesis Simultaneously during an Entire Diurnal Period.

PubMed

Klatt, Judith M; de Beer, Dirk; Häusler, Stefan; Polerecky, Lubos

2016-01-01

We used microsensors to study the regulation of anoxygenic and oxygenic photosynthesis (AP and OP, respectively) by light and sulfide in a cyanobacterium dominating microbial mats from cold sulfidic springs. Both photosynthetic modes were performed simultaneously over all H 2 S concentrations (1-2200 μM) and irradiances (4-52 μmol photons m -2 s -1 ) tested. AP increased with H 2 S concentration while the sum of oxygenic and anoxygenic photosynthetic rates was constant at each light intensity. Thus, the total photosynthetically driven electron transport rate was solely controlled by the irradiance level. The partitioning between the rates of these two photosynthetic modes was regulated by both light and H 2 S concentration. The plastoquinone pool (PQ) receives electrons from sulfide:quinone:reductase (SQR) in AP and from photosystem II (PSII) in OP. It is thus the link in the electron transport chain where both pathways intersect, and the compound that controls their partitioning. We fitted our data with a model of the photosynthetic electron transport that includes the kinetics of plastoquinone reduction and oxidation. The model results confirmed that the observed partitioning between photosynthetic modes can be explained by a simple kinetic control based on the affinity of SQR and PSII toward PQ. The SQR enzyme and PSII have similar affinities toward PQ, which explains the concurrent OP and AP over an astonishingly wide range of H 2 S concentrations and irradiances. The elegant kinetic control of activity makes the cyanobacterium successful in the fluctuating spring environment. We discuss how these specific regulation mechanisms may have played a role in ancient H 2 S-rich oceans.

Cyanobacteria in Sulfidic Spring Microbial Mats Can Perform Oxygenic and Anoxygenic Photosynthesis Simultaneously during an Entire Diurnal Period

PubMed Central

Klatt, Judith M.; de Beer, Dirk; Häusler, Stefan; Polerecky, Lubos

2016-01-01

We used microsensors to study the regulation of anoxygenic and oxygenic photosynthesis (AP and OP, respectively) by light and sulfide in a cyanobacterium dominating microbial mats from cold sulfidic springs. Both photosynthetic modes were performed simultaneously over all H2S concentrations (1–2200 μM) and irradiances (4–52 μmol photons m-2 s-1) tested. AP increased with H2S concentration while the sum of oxygenic and anoxygenic photosynthetic rates was constant at each light intensity. Thus, the total photosynthetically driven electron transport rate was solely controlled by the irradiance level. The partitioning between the rates of these two photosynthetic modes was regulated by both light and H2S concentration. The plastoquinone pool (PQ) receives electrons from sulfide:quinone:reductase (SQR) in AP and from photosystem II (PSII) in OP. It is thus the link in the electron transport chain where both pathways intersect, and the compound that controls their partitioning. We fitted our data with a model of the photosynthetic electron transport that includes the kinetics of plastoquinone reduction and oxidation. The model results confirmed that the observed partitioning between photosynthetic modes can be explained by a simple kinetic control based on the affinity of SQR and PSII toward PQ. The SQR enzyme and PSII have similar affinities toward PQ, which explains the concurrent OP and AP over an astonishingly wide range of H2S concentrations and irradiances. The elegant kinetic control of activity makes the cyanobacterium successful in the fluctuating spring environment. We discuss how these specific regulation mechanisms may have played a role in ancient H2S-rich oceans. PMID:28018309

Spring operated accelerator and constant force spring mechanism therefor

NASA Technical Reports Server (NTRS)

Shillinger, G. L., Jr. (Inventor)

1977-01-01

A spring assembly consisting of an elongate piece of flat spring material formed into a spiral configuration and a free running spool in circumscribing relation to which this spring is disposed was developed. The spring has a distal end that is externally accessible so that when the distal end is drawn along a path, the spring unwinds against a restoring force present in the portion of the spring that resides in a transition region between a relatively straight condition on the path and a fully wound condition on the spool. When the distal end is released, the distal end is accelerated toward the spool by the force existing at the transition region which force is proportional to the cross-sectional area of the spring.

Spring constant of a tuning-fork sensor for dynamic force microscopy

PubMed Central

Lange, Manfred; Schmuck, Merlin; Schmidt, Nico; Möller, Rolf

2012-01-01

Summary We present an overview of experimental and numerical methods to determine the spring constant of a quartz tuning fork in qPlus configuration. The simple calculation for a rectangular cantilever is compared to the values obtained by the analysis of the thermal excitation and by the direct mechanical measurement of the force versus displacement. To elucidate the difference, numerical simulations were performed taking account of the real geometry including the glue that is used to mount the tuning fork. PMID:23365793

Are black holes springlike?

NASA Astrophysics Data System (ADS)

Good, Michael R. R.; Ong, Yen Chin

2015-02-01

A (3 +1 )-dimensional asymptotically flat Kerr black hole angular speed Ω+ can be used to define an effective spring constant, k =m Ω+2. Its maximum value is the Schwarzschild surface gravity, k =κ , which rapidly weakens as the black hole spins down and the temperature increases. The Hawking temperature is expressed in terms of the spring constant: 2 π T =κ -k . Hooke's law, in the extremal limit, provides the force F =1 /4 , which is consistent with the conjecture of maximum force in general relativity.

Energy analysis of a DEAP based cylindrical actuator coupled with a radial negative stiffness spring

NASA Astrophysics Data System (ADS)

Chavanne, Jonathan; Civet, Yoan; Perriard, Yves

2017-04-01

The main problem to obtain considerable deformation with dielectric electro-active polymer based technology is the electrical breakdown. A simple solution consists in pre-stretching the elastomer before activating it which cancels the snap-through effect and thus avoid reaching the electrical limit. Due to the stress characteristic of the DEAP, it could be demonstrated that a spring with a negative stiffness provides the best strain. In this paper, a new design of a monostable spring with a negative stiffness is suggested for a DEAP tubular shape actuator. The particularity of the proposed solution is the radial direction of the displacement with a special load characteristic. In order to determine the performance of the system, the mechanical and electrical behaviour are investigated through analytical models with the assumption that the axial stretch stays constant. A finite element method is used to validate these latter and maximal error lower than 2% is reported. The energy chain conversion is developed in detail which allows studying all the energies transferred from both the electrical input and any pre-stretch solution to the membrane during a cycle of activation. From these models, the negative stiffness spring is compared to the common solution, i.e a constant pressure or a linear positive spring, to pre-stretch a cylindrical EAP. The results show that the linear spring always removes the snap-through behaviour contrary to the constant pressure. Depending on the geometry, the monostable solution cancels also this latter and owns a better energy transfer from the power supply to the elastomer (around 50% against 40% for the linear spring) or a better stroke compared to the linear spring. Furthermore, due to the hollow in its stress characteristic, the cylindrical shaped actuator associated to a linear spring or the proposed spring allows increasing the strain. Through the different analytical models, the definition of the electrical breakdown and the analysis of the limits of the stresses, a qualitative study of the performance is given for the different pre-stretches.

Pumping tests of well Campbell et al. No. 2, Gila Hot Springs, Grant County, New Mexico

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

Schwab, G.E.; Summers, W.K.; Colpitts, R.M. Jr.

1982-03-01

Well Campbell et al. No. 2 near Gila Hot Springs in southwestern New Mexico (Section 5, Township 13 South, Range 13 West) was pumped for a five-step test and a 48-hour constant-rate test during October 1981. Measurements included depth to water in the pumping well and two observation wells, and discharge rates at the pumping well and two springs. The water level in the pumping well responded during both tests. However, water-level changes in the observation wells were too small for analytical use and discharge rates from the springs showed no change. Chemical analyses of water samples collected from twomore » springs and the pumping well show very similar water chemistries. Estimates of hydraulic properties show transmissivity from 12,000 to 14,000 gpd/ft and a storativity of 0.05. Combining these parameters with well data gives the first-year optimum discharge rate as 50 gpm with 20 feet of drawdown. Pumping this well at 50 gpm for forty years should produce only small water-level changes in wells a few hundred feet away. It would diminish the flow of the springs, and for planning purposes the combined discharge of the springs and well should be considered constant.« less

Variable stiffness torsion springs

NASA Astrophysics Data System (ADS)

Alhorn, Dean C.; Polites, Michael E.

1994-05-01

In a torsion spring the spring action is a result of the relationships between the torque applied in twisting the spring, the angle through which the torsion spring twists, and the modulus of elasticity of the spring material in shear. Torsion springs employed industrially have been strips, rods, or bars, generally termed shafts, capabable of being flexed by twisting their axes. They rely on the variations in shearing forces to furnish an internal restoring torque. In the torsion springs herein the restoring torque is external and therefore independent of the shearing modulus of elasticity of the torsion spring shaft. Also provided herein is a variable stiffness torsion spring. This torsion spring can be so adjusted as to have a given spring constant. Such variable stiffness torsion springs are extremely useful in gimballed payloads such as sensors, telescopes, and electronic devices on such platforms as a space shuttle or a space station.

Variable stiffness torsion springs

NASA Technical Reports Server (NTRS)

Alhorn, Dean C. (Inventor); Polites, Michael E. (Inventor)

1995-01-01

In a torsion spring the spring action is a result of the relationships between the torque applied in twisting the spring, the angle through which the torsion spring twists, and the modulus of elasticity of the spring material in shear. Torsion springs employed industrially have been strips, rods, or bars, generally termed shafts, capabable of being flexed by twisting their axes. They rely on the variations in shearing forces to furnish an internal restoring torque. In the torsion springs herein the restoring torque is external and therefore independent of the shearing modulus of elasticity of the torsion spring shaft. Also provided herein is a variable stiffness torsion spring. This torsion spring can be so adjusted as to have a given spring constant. Such variable stiffness torsion springs are extremely useful in gimballed payloads such as sensors, telescopes, and electronic devices on such platforms as a space shuttle or a space station.

Variable stiffness torsion springs

NASA Astrophysics Data System (ADS)

Alhorn, Dean C.; Polites, Michael E.

1995-08-01

In a torsion spring the spring action is a result of the relationships between the torque applied in twisting the spring, the angle through which the torsion spring twists, and the modulus of elasticity of the spring material in shear. Torsion springs employed industrially have been strips, rods, or bars, generally termed shafts, capabable of being flexed by twisting their axes. They rely on the variations in shearing forces to furnish an internal restoring torque. In the torsion springs herein the restoring torque is external and therefore independent of the shearing modulus of elasticity of the torsion spring shaft. Also provided herein is a variable stiffness torsion spring. This torsion spring can be so adjusted as to have a given spring constant. Such variable stiffness torsion springs are extremely useful in gimballed payloads such as sensors, telescopes, and electronic devices on such platforms as a space shuttle or a space station.

Variable stiffness torsion springs

NASA Technical Reports Server (NTRS)

Alhorn, Dean C. (Inventor); Polites, Michael E. (Inventor)

1994-01-01

In a torsion spring the spring action is a result of the relationships between the torque applied in twisting the spring, the angle through which the torsion spring twists, and the modulus of elasticity of the spring material in shear. Torsion springs employed industrially have been strips, rods, or bars, generally termed shafts, capabable of being flexed by twisting their axes. They rely on the variations in shearing forces to furnish an internal restoring torque. In the torsion springs herein the restoring torque is external and therefore independent of the shearing modulus of elasticity of the torsion spring shaft. Also provided herein is a variable stiffness torsion spring. This torsion spring can be so adjusted as to have a given spring constant. Such variable stiffness torsion springs are extremely useful in gimballed payloads such as sensors, telescopes, and electronic devices on such platforms as a space shuttle or a space station.

Self-assembly of suspended graphene wrinkles with high pre-tension and elastic property

NASA Astrophysics Data System (ADS)

Yang, Liusi; Niu, Tianxiao; Zhang, Hui; Xu, Wenjing; Zou, Mingchu; Xu, Lu; Cao, Guoxin; Cao, Anyuan

2017-12-01

Wrinkles exist universally in graphene-based structures, yet their controlled fabrication remains challenging; most graphene wrinkles have been produced either in attachment to elastic substrates or limited in small single sheets. Here, we utilize the phenomenon of gel-cracking to generate uniaxial strains locally on solution-precipitated graphene oxide (GO) sheets, thus creating suspended and aligned wrinkles over the trenches between cracked TiO2 islands. In particular, those GO wrinkles are subjected to a high pre-tension, which is important for making stable suspended configuration, as confirmed by theoretical calculations based on the wrinkle geometry and measured spring constants, respectively. As a result, in situ atomic force microscope indentation reveals elastic deformation with tunable spring constants depending on the gap width. We further obtain chemically reduced GO wrinkles with enhanced spring constants and reversible behavior after 1000 indentation cycles. Our suspended and aligned graphene wrinkles have potential applications in many areas such as sensors, actuators, and micro/nano electromechanical systems.

Effect of cantilever geometry on the optical lever sensitivities and thermal noise method of the atomic force microscope.

PubMed

Sader, John E; Lu, Jianing; Mulvaney, Paul

2014-11-01

Calibration of the optical lever sensitivities of atomic force microscope (AFM) cantilevers is especially important for determining the force in AFM measurements. These sensitivities depend critically on the cantilever mode used and are known to differ for static and dynamic measurements. Here, we calculate the ratio of the dynamic and static sensitivities for several common AFM cantilevers, whose shapes vary considerably, and experimentally verify these results. The dynamic-to-static optical lever sensitivity ratio is found to range from 1.09 to 1.41 for the cantilevers studied - in stark contrast to the constant value of 1.09 used widely in current calibration studies. This analysis shows that accuracy of the thermal noise method for the static spring constant is strongly dependent on cantilever geometry - neglect of these dynamic-to-static factors can induce errors exceeding 100%. We also discuss a simple experimental approach to non-invasively and simultaneously determine the dynamic and static spring constants and optical lever sensitivities of cantilevers of arbitrary shape, which is applicable to all AFM platforms that have the thermal noise method for spring constant calibration.

40 CFR 211.210-2 - Labeling requirements.

Code of Federal Regulations, 2010 CFR

2010-07-01

... constant); (ii) Ear cup volume or shape; (iii) Mounting of ear cup on head band; (iv) Ear cushion; (v... tension (spring constant); (ii) Mounting of plug on head band; (iii) Shape of plug; (iv) Material...

Exercise support for therapy

NASA Technical Reports Server (NTRS)

Long, M. J.; Irick, S. C.

1976-01-01

Constant-value weight-relieving apparatus, which moves on rollers on overhead track, supports weight of walking, stooping, squatting, or standing patient with combination of multiple pulleys and spring clusters. Individually preselected support force is constant for all movements.

Detection of Hb Constant Spring [α142, Term→Gln, TAA>CAA (α2)] in heterozygotes combined with β-thalassemia.

PubMed

Li, You-Qiong; Li, Ru; Li, Dong-Zhi

2013-01-01

Hb Constant Spring [Hb CS, α142, Term→Gln, TAA>CAA (α2)] is a nondeletional form of α-thalassemia (α-thal) that is most prevalent in Southern Chinese and Southeast Asian populations. We previously found that Hb CS trait could efficiently be screened using Sebia Capillarys2. In this study, we report that Hb CS heterozygotes combined with β-thal could not be detected by the Sebia Capillarys2 method due to the very small amount of Hb CS.

Airbag vent valve and system

NASA Technical Reports Server (NTRS)

Peterson, Leslie D. (Inventor); Zimmermann, Richard E. (Inventor)

2001-01-01

An energy absorbing airbag system includes one or more vent valve assemblies for controlling the release of airbag inflation gases to maintain inflation gas pressure within an airbag at a substantially constant pressure during a ride-down of an energy absorbing event. Each vent valve assembly includes a cantilever spring that is flat in an unstressed condition and that has a free end portion. The cantilever spring is secured to an exterior surface of the airbag housing and flexed to cause the second free end portion of the cantilever spring to be pressed, with a preset force, against a vent port or a closure covering the vent port to seal the vent port until inflation gas pressure within the airbag reaches a preselected value determined by the preset force whereupon the free end portion of the cantilever spring is lifted from the vent port by the inflation gases within the airbag to vent the inflation gases from within the airbag. The resilience of the cantilever spring maintains a substantially constant pressure within the airbag during a ride-down portion of an energy absorbing event by causing the cantilever spring to vent gases through the vent port whenever the pressure of the inflation gases reaches the preselected value and by causing the cantilever spring to close the vent port whenever the pressure of the inflation gases falls below the preselected value.

Application of spring tabs to elevator controls

NASA Technical Reports Server (NTRS)

Phillips, William H

1944-01-01

Equations are presented for calculating the stick-force characteristics obtained with a spring-tab type of elevator control. The main problems encountered in the design of a satisfactory elevator spring tab are to provide stick forces in the desired range, to maintain the force per g sufficiently constant throughout the speed range, to avoid undesirable "feel" of the control in ground handling or in flight at low airspeeds, and to prevent flutter. Examples are presented to show the design features of spring tabs required to solve these problems for airplanes of various sizes.

A Constant-Force Resistive Exercise Unit

NASA Technical Reports Server (NTRS)

Colosky, Paul; Ruttley, Tara

2010-01-01

A constant-force resistive exercise unit (CFREU) has been invented for use in both normal gravitational and microgravitational environments. In comparison with a typical conventional exercise machine, this CFREU weighs less and is less bulky: Whereas weight plates and associated bulky supporting structures are used to generate resistive forces in typical conventional exercise machines, they are not used in this CFREU. Instead, resistive forces are generated in this CFREU by relatively compact, lightweight mechanisms based on constant-torque springs wound on drums. Each such mechanism is contained in a module, denoted a resistive pack, that includes a shaft for making a torque connection to a cable drum. During a stroke of resistive exercise, the cable is withdrawn from the cable drum against the torque exerted by the resistance pack. The CFREU includes a housing, within which can be mounted one or more resistive pack(s). The CFREU also includes mechanisms for engaging any combination of (1) one or more resistive pack(s) and (2) one or more spring(s) within each resistive pack to obtain a desired level of resistance.

Influence of adhesive rough surface contact on microswitches

NASA Astrophysics Data System (ADS)

Wu, Ling; Rochus, V.; Noels, L.; Golinval, J. C.

2009-12-01

Stiction is a major failure mode in microelectromechanical systems (MEMS). Undesirable stiction, which results from contact between surfaces, threatens the reliability of MEMS severely as it breaks the actuation function of MEMS switches, for example. Although it may be possible to avoid stiction by increasing restoring forces using high spring constants, it follows that the actuation voltage has also to be increased significantly, which reduces the efficiency. In our research, an electrostatic-structural analysis is performed to estimate the proper design range of the equivalent spring constant, which is the main factor of restoring force in MEMS switches. The upper limit of equivalent spring constant is evaluated based on the initial gap width, the dielectric thickness, and the expected actuation voltage. The lower limit is assessed on the value of adhesive forces between the two contacting rough surfaces. The MEMS devices studied here are assumed to work in a dry environment. In these operating conditions only the van der Waals forces have to be considered for adhesion. A statistical model is used to simulate the rough surface, and the Maugis's model is combined with Kim's expansion to calculate adhesive forces. In the resulting model, the critical value of the spring stiffness depends on the material and surface properties, such as the elastic modulus, surface energy, and surface roughness. The aim of this research is to propose simple rules for design purposes.

In Vivo Force Decay of Niti Closed Coil Springs

PubMed Central

Cox, Crystal; Nguyen, Tung; Koroluk, Lorne; Ko, Ching-Chang

2014-01-01

Introduction Nickel-titanium (NiTi) closed coil springs are purported to deliver constant forces over extended ranges of activation and working times. In vivo studies supporting this claim are limited. The objective of this study is to evaluate changes in force decay properties of NiTi closed coil springs after clinical use. Methods Pseudoelastic force-deflection curves for 30 NiTi coil springs (used intra-orally) and 15 matched laboratory control springs (simulated intra-oral conditions - artificial saliva, 37°C) were tested pre- and post-retrieval via Dynamic Mechanical Analysis (DMA) and the Instron machine, respectively, to evaluate amount of force loss and hysteresis change following 4, 8, or 12 weeks of working time (n=10 per group). Effect of the oral environment and clinical use on force properties were evaluated by comparing in vivo and in vitro data. Results The springs studied showed a statistically significant decrease in force (~12%) following 4 weeks of clinical use (p<0.01), with a further significant decrease (~7%) from 4–8 weeks (p=0.03) and force levels appearing to remain steady thereafter. Clinical space closure at an average rate of 0.91mm per month was still observed despite this decrease in force. In vivo and in vitro force loss data were not statistically different. Conclusions NiTi closed coil springs do not deliver constant forces when used intra-orally, but they still allow for space closure rates of ~1mm/month. PMID:24703289

Quantitative comparison of two independent lateral force calibration techniques for the atomic force microscope.

PubMed

Barkley, Sarice S; Deng, Zhao; Gates, Richard S; Reitsma, Mark G; Cannara, Rachel J

2012-02-01

Two independent lateral-force calibration methods for the atomic force microscope (AFM)--the hammerhead (HH) technique and the diamagnetic lateral force calibrator (D-LFC)--are systematically compared and found to agree to within 5 % or less, but with precision limited to about 15 %, using four different tee-shaped HH reference probes. The limitations of each method, both of which offer independent yet feasible paths toward traceable accuracy, are discussed and investigated. We find that stiff cantilevers may produce inconsistent D-LFC values through the application of excessively high normal loads. In addition, D-LFC results vary when the method is implemented using different modes of AFM feedback control, constant height and constant force modes, where the latter is more consistent with the HH method and closer to typical experimental conditions. Specifically, for the D-LFC apparatus used here, calibration in constant height mode introduced errors up to 14 %. In constant force mode using a relatively stiff cantilever, we observed an ≈ 4 % systematic error per μN of applied load for loads ≤ 1 μN. The issue of excessive load typically emerges for cantilevers whose flexural spring constant is large compared with the normal spring constant of the D-LFC setup (such that relatively small cantilever flexural displacements produce relatively large loads). Overall, the HH method carries a larger uncertainty, which is dominated by uncertainty in measurement of the flexural spring constant of the HH cantilever as well as in the effective length dimension of the cantilever probe. The D-LFC method relies on fewer parameters and thus has fewer uncertainties associated with it. We thus show that it is the preferred method of the two, as long as care is taken to perform the calibration in constant force mode with low applied loads.

Volusia Blue Spring - A Hydrological Treasure

USGS Publications Warehouse

German, Edward R.

2008-01-01

Springs are natural openings in the ground through which water beneath the surface discharges into hydrologic features such as lakes, rivers, or the ocean. The beautiful springs and spring rivers are among Florida's most valued natural resources; their gemlike refreshing waters have been a focal point of life from prehistoric times to the present (2008). The steady flow of freshwater at a nearly constant water temperature attracted animals now long absent from Florida's landscape. Fossil remains and human artifacts, discovered by divers from many spring runs, attest to the importance of springs to the State's earliest inhabitants. Explorers of Florida, from Ponce de Leon to John and William Bartram and others, often mentioned the springs that were scattered across central and northern Florida. As colonists and settlers began to inhabit Florida, springs continued to be the focus of human activity, becoming sites of missions, towns, and steamboat landings.

Fast antibody fragment motion: flexible linkers act as entropic spring

PubMed Central

Stingaciu, Laura R.; Ivanova, Oxana; Ohl, Michael; Biehl, Ralf; Richter, Dieter

2016-01-01

A flexible linker region between three fragments allows antibodies to adjust their binding sites to an antigen or receptor. Using Neutron Spin Echo Spectroscopy we observed fragment motion on a timescale of 7 ns with motional amplitudes of about 1 nm relative to each other. The mechanistic complexity of the linker region can be described by a spring model with Brownian motion of the fragments in a harmonic potential. Displacements, timescale, friction and force constant of the underlying dynamics are accessed. The force constant exhibits a similar strength to an entropic spring, with friction of the fragment matching the unbound state. The observed fast motions are fluctuations in pre-existing equilibrium configurations. The Brownian motion of domains in a harmonic potential is the appropriate model to examine functional hinge motions dependent on the structural topology and highlights the role of internal forces and friction to function. PMID:27020739

Fast antibody fragment motion: flexible linkers act as entropic spring

DOE PAGES

Stingaciu, Laura R.; Ivanova, Oxana; Ohl, Michael; ...

2016-03-29

A flexible linker region between three fragments allows antibodies to adjust their binding sites to an antigen or receptor. Using Neutron Spin Echo Spectroscopy we observed fragment motion on a timescale of 7 ns with motional amplitudes of about 1 nm relative to each other. The mechanistic complexity of the linker region can be described by a spring model with Brownian motion of the fragments in a harmonic potential. Displacements, timescale, friction and force constant of the underlying dynamics are accessed. The force constant exhibits a similar strength to an entropic spring, with friction of the fragment matching the unboundmore » state. The observed fast motions are fluctuations in pre-existing equilibrium configurations. In conclusion, the Brownian motion of domains in a harmonic potential is the appropriate model to examine functional hinge motions dependent on the structural topology and highlights the role of internal forces and friction to function.« less

Fast antibody fragment motion: flexible linkers act as entropic spring.

PubMed

Stingaciu, Laura R; Ivanova, Oxana; Ohl, Michael; Biehl, Ralf; Richter, Dieter

2016-03-29

A flexible linker region between three fragments allows antibodies to adjust their binding sites to an antigen or receptor. Using Neutron Spin Echo Spectroscopy we observed fragment motion on a timescale of 7 ns with motional amplitudes of about 1 nm relative to each other. The mechanistic complexity of the linker region can be described by a spring model with Brownian motion of the fragments in a harmonic potential. Displacements, timescale, friction and force constant of the underlying dynamics are accessed. The force constant exhibits a similar strength to an entropic spring, with friction of the fragment matching the unbound state. The observed fast motions are fluctuations in pre-existing equilibrium configurations. The Brownian motion of domains in a harmonic potential is the appropriate model to examine functional hinge motions dependent on the structural topology and highlights the role of internal forces and friction to function.

Seventeen-year trends in spring and autumn phenophases of Betula pubescens in a boreal environment.

PubMed

Poikolainen, Jarmo; Tolvanen, Anne; Karhu, Jouni; Kubin, Eero

2016-08-01

Trends in the timing of spring and autumn phenophases of Betula pubescens were investigated in the southern, middle, and northern boreal zones in Finland. The field observations were carried out at 21 sites in the Finnish National Phenological Network in 1997-2013. The effective temperature sum of the thermal growth period, i.e. the sum of the positive differences between diurnal mean temperatures and 5 °C (ETS1), increased annually on average by 6-7 degree day units. Timing of bud burst remained constant in the southern and middle boreal zones but advanced annually by 0.5 day in the northern boreal zone. The effective temperature sum at bud burst (ETS2) showed no trend in the southern and middle boreal zones, whereas ETS2 increased on average from 20-30 to 50 degree day units in the northern boreal zone, almost to the same level as in the other zones. Increase in ETS2 indicates that the trees did not start their growth in very early spring despite warmer spring temperatures. The timing of leaf colouring and leaf fall remained almost constant in the southern boreal zones, whereas these advanced annually by 0.3 and 0.6 day in the middle boreal zone and by 0.6 and 0.4 day in the northern boreal zone, respectively. The duration of the growth period remained constant in all boreal zones. The results indicate high buffering capacity of B. pubescens against temperature changes. The study also shows the importance of the duration of phenological studies: some trends in spring phenophases had levelled out, while new trends in autumn phases had emerged after earlier studies in the same network for a shorter observation period.

Research on the response characteristics of solenoid valve of the air-jet loom by simulation

NASA Astrophysics Data System (ADS)

Jin, Yuzhen; Deng, Ruoyu; Jin, Yingzi; Hu, Xudong

2013-12-01

Solenoid valve is one of the executive parts of weft insertion control system. According to the response characteristics of the solenoid valve, an improved design becomes a necessity. Firstly, the numerical model was established after analyzing the solenoid valve during its start-up and shut-down. Comparing the simulation data with the practical data, it is verified that the numerical simulation model has a high feasibility. Secondly, excitation voltage and spring pre-compression were adjusted respectively, and the response rules after adjusting were investigated. The research of the study shows: the response time tends to be inverse proportional to the excitation voltage during start-up, and it becomes a constant value with the increase of the excitation voltage; the response time is proportional to the spring pre-compression when the solenoid valve starts up, it is inverse proportional to spring pre-compression when the solenoid valve shuts down. And the total response time is a constant value with the increase of the spring pre-compression. Therefore, the value of the excitation voltage and the spring pre-compression should be selected when the curve is becoming flatten. The results of the research can provide the reference to the further development of the solenoid valve.

Implementation of the glacial rebound prestress advection correction in general-purpose finite element analysis software: Springs versus foundations

NASA Astrophysics Data System (ADS)

Schmidt, Peter; Lund, Björn; Hieronymus, Christoph

2012-03-01

When general-purpose finite element analysis software is used to model glacial isostatic adjustment (GIA), the first-order effect of prestress advection has to be accounted for by the user. We show here that the common use of elastic foundations at boundaries between materials of different densities will produce incorrect displacements, unless the boundary is perpendicular to the direction of gravity. This is due to the foundations always acting perpendicular to the surface to which they are attached, while the body force they represent always acts in the direction of gravity. If prestress advection is instead accounted for by the use of elastic spring elements in the direction of gravity, the representation will be correct. The use of springs adds a computation of the spring constants to the analysis. The spring constant for a particular node is defined by the product of the density contrast at the boundary, the gravitational acceleration, and the area supported by the node. To be consistent with the finite element formulation, the area is evaluated by integration of the nodal shape functions. We outline an algorithm for the calculation and include a Python script that integrates the shape functions over a bilinear quadrilateral element. For linear rectangular and triangular elements, the area supported by each node is equal to the element area divided the number of defining nodes, thereby simplifying the computation. This is, however, not true in the general nonrectangular case, and we demonstrate this with a simple 1-element model. The spring constant calculation is simple and performed in the preprocessing stage of the analysis. The time spent on the calculation is more than compensated for by a shorter analysis time, compared to that for a model with foundations. We illustrate the effects of using springs versus foundations with a simple two-dimensional GIA model of glacial loading, where the Earth model has an inclined boundary between the overlying elastic layer and the lower viscoelastic layer. Our example shows that the error introduced by the use of foundations is large enough to affect an analysis based on high-accuracy geodetic data.

Fluorescence-based multi-parameter approach to characterize dynamics of organic carbon, faecal bacteria and particles at alpine karst springs.

PubMed

Frank, Simon; Goeppert, Nadine; Goldscheider, Nico

2018-02-15

Karst springs, especially in alpine regions, are important for drinking water supply but also vulnerable to contamination, especially after rainfall events. This high variability of water quality requires rapid quantification of contamination parameters. Here, we used a fluorescence-based multi-parameter approach to characterize the dynamics of organic carbon, faecal bacteria, and particles at three alpine karst springs. We used excitation emission matrices (EEMs) to identify fluorescent dissolved organic material (FDOM). At the first system, peak A fluorescence and total organic carbon (TOC) were strongly correlated (Spearman's r s of 0.949), indicating that a large part of the organic matter is related to humic-like substances. Protein-like fluorescence and cultivation-based determination of coliform bacteria also had a significant correlation with r s =0.734, indicating that protein-like fluorescence is directly related to faecal pollution. At the second system, which has two spring outlets, the absolute values of all measured water-quality parameters were lower; there was a significant correlation between TOC and humic-like fluorescence (r s =0.588-0.689) but coliform bacteria and protein-like fluorescence at these two springs were not correlated. Additionally, there was a strong correlation (r s =0.571-0.647) between small particle fractions (1.0 and 2.0μm), a secondary turbidity peak and bacteria. At one of these springs, discharge was constant despite the reaction of all other parameters to the rainfall event. Our results demonstrated that i) all three springs showed fast and marked responses of all investigated water-quality parameters after rain events; ii) a constant discharge does not necessarily mean constant water quality; iii) at high contamination levels, protein-like fluorescence is a good indicator of bacterial contamination, while at low contamination levels no correlation between protein-like fluorescence and bacterial values was detected; and iv) a combination of fluorescence measurements and particle-size analysis is a promising approach for a rapid assessment of organic contamination, especially relative to time-consuming conventional bacterial determination methods. Copyright © 2017 Elsevier B.V. All rights reserved.

4. INTERIOR OF DRAFT REGULATOR & MIXING DAMPER COMBINATION. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

4. INTERIOR OF DRAFT REGULATOR & MIXING DAMPER COMBINATION. - Hot Springs National Park, Bathhouse Row, Lamar Bathhouse: Mechanical & Piping Systems, State Highway 7, 1 mile north of U.S. Highway 70, Hot Springs, Garland County, AR

In-vivo force decay of nickel-titanium closed-coil springs.

PubMed

Cox, Crystal; Nguyen, Tung; Koroluk, Lorne; Ko, Ching-Chang

2014-04-01

Nickel-titanium closed-coil springs are purported to deliver constant forces over extended ranges of activation and working times. In-vivo studies supporting this claim are limited. The objective of this study was to evaluate changes in force-decay properties of nickel-titanium closed-coil springs after clinical use. Pseudoelastic force-deflection curves for 30 nickel-titanium coil springs (used intraorally) and 15 matched laboratory control springs (simulated intraoral conditions: artificial saliva, 37°C) were tested before and after retrieval via dynamic mechanical analysis and a testing machine, respectively, to evaluate the amounts of force-loss and hysteresis change after 4, 8, or 12 weeks of working time (n = 10 per group). The effects of the oral environment and clinical use on force properties were evaluated by comparing in-vivo and in-vitro data. The springs studied showed a statistically significant decrease in force (approximately 12%) after 4 weeks of clinical use (P <0.01), with a further significant decrease (approximately 7%) from 4 to 8 weeks (P = 0.03), and force levels appearing to remain steady thereafter. Clinical space closure at an average rate of 0.91 mm per month was still observed despite this decrease in force. In-vivo and in-vitro force-loss data were not statistically different. Nickel-titanium closed-coil springs do not deliver constant forces when used intraorally, but they still allow for space-closure rates of approximately 1 mm per month. Copyright © 2014 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

Wrap spring clutch syringe ram and frit mixer

DOEpatents

Simpson, Frank B.

2006-07-25

A wrap spring clutch syringe ram pushes at least one syringe with virtually instantaneous starting and stopping, and with constant motion at a defined velocity during the intervening push. The wrap spring clutch syringe ram includes an electric motor, a computer, a flywheel, a wrap spring clutch, a precision lead screw, a slide platform, and syringe reservoirs, a mixing chamber, and a reaction incubation tube. The electric motor drives a flywheel and the wrap spring clutch couples the precision lead screw to the flywheel when a computer enables a solenoid of the wrap spring clutch. The precision lead screw drives a precision slide which causes syringes to supply a portion of solution into the mixing chamber and the incubation tube. The wrap spring clutch syringe ram is designed to enable the quantitative study of solution phase chemical and biochemical reactions, particularly those reactions that occur on the subsecond time scale.

Differential regulation of sodium-potassium pump isoforms during smolt development and seawater exposure of Atlantic salmon

USGS Publications Warehouse

McCormick, Stephen D.; Regish, Amy M.; Christensen, Arne K.; Björnsson, Björn Thrandur

2013-01-01

Freshwater and seawater isoforms of the alpha subunit of Na+/K+-ATPase (NKA) have previously been identified in gill ionocytes of Atlantic salmon (Salmo salar). In the present study we examine the abundance and cellular localization of these isoforms during the parr–smolt transformation, a developmental process that is preparatory for seawater entry. The abundance of NKAα1a was lower in smolts than in parr, remained relatively constant during spring and decreased in summer. NKAα1b increased tenfold in smolts during spring, peaking in late April, coincident with downstream migration and increased salinity tolerance. NKAα1b increased a further twofold after seawater exposure of smolts, whereas NKAα1a decreased by 98%. The abundance of NKAα1b-positive, and NKAα1b and NKAα1a co-labeled ionocytes increased during smolt development, whereas the number of NKAα1a cells decreased. After seawater exposure of smolts, NKAα1b-positive ionocytes increased, NKAα1a-positive cells decreased, and co-labeled cells disappeared. Plasma growth hormone and cortisol increased during spring in smolts, but not in parr, peaking just prior to the highest levels of NKAα1b. The results indicate that the increase in the abundance of NKAα1b during smolt development is directly linked to the increase in salinity tolerance that occurs at this stage, but that significant changes also occur after seawater exposure. Spring increases in circulating levels of growth hormone and cortisol indicate that these hormones may be instrumental in upregulating NKAα1b during smolt development.

PLENUM INTERIOR, SHOWING ARRANGEMENT OF DRAFT REGULATORS AND FLUES. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

PLENUM INTERIOR, SHOWING ARRANGEMENT OF DRAFT REGULATORS AND FLUES. - Hot Springs National Park, Bathhouse Row, Superior Bathhouse: Mechanical & Piping Systems, State Highway 7, 1 mile north of U.S. Highway 70, Hot Springs, Garland County, AR

Braking System for Wind Turbines

NASA Technical Reports Server (NTRS)

Krysiak, J. E.; Webb, F. E.

1987-01-01

Operating turbine stopped smoothly by fail-safe mechanism. Windturbine braking systems improved by system consisting of two large steel-alloy disks mounted on high-speed shaft of gear box, and brakepad assembly mounted on bracket fastened to top of gear box. Lever arms (with brake pads) actuated by spring-powered, pneumatic cylinders connected to these arms. Springs give specific spring-loading constant and exert predetermined load onto brake pads through lever arms. Pneumatic cylinders actuated positively to compress springs and disengage brake pads from disks. During power failure, brakes automatically lock onto disks, producing highly reliable, fail-safe stops. System doubles as stopping brake and "parking" brake.

Base excitation testing system using spring elements to pivotally mount wind turbine blades

DOEpatents

Cotrell, Jason; Hughes, Scott; Butterfield, Sandy; Lambert, Scott

2013-12-10

A system (1100) for fatigue testing wind turbine blades (1102) through forced or resonant excitation of the base (1104) of a blade (1102). The system (1100) includes a test stand (1112) and a restoring spring assembly (1120) mounted on the test stand (1112). The restoring spring assembly (1120) includes a primary spring element (1124) that extends outward from the test stand (1112) to a blade mounting plate (1130) configured to receive a base (1104) of blade (1102). During fatigue testing, a supported base (1104) of a blad (1102) may be pivotally mounted to the test stand (1112) via the restoring spring assembly (1120). The system (1100) may include an excitation input assembly (1140) that is interconnected with the blade mouting plate (1130) to selectively apply flapwise, edgewise, and/or pitch excitation forces. The restoring spring assemply (1120) may include at least one tuning spring member (1127) positioned adjacent to the primary spring element (1124) used to tune the spring constant or stiffness of the primary spring element (1124) in one of the excitation directions.

Convection currents enhancement of the spring constant in optical tweezers

NASA Astrophysics Data System (ADS)

Zenteno-Hernández, J. A.; Gómez-Vieyra, A.; Torres-Hurtado, S. A.; Ramirez-San-Juan, J. C.; Ramos-García, R.

2016-09-01

In this work we demonstrate the increasing of the trap stiffness (spring constant) constant of an optical trap of particles suspended in water by laser-induced convection currents. These currents are the result of thermal gradients created by a light absorption in a thin layer of hydrogenated amorphous silicon (a:Si-H) deposited at the bottom of cell. Since convection currents (and therefore drag forces) are symmetric around the beam focus particles trapped by the beam are further contained. Around the focus the drag force is directed upwards and partially compensated by radiation pressure depending on the laser power increasing the stiffness of the optical trapping increases significatively so a particle trapped could dragged (by moving the translation stage leaving the beam fixed) at velocities as high as 90μm/s without escaping the trap, whereas with no a:Si-H film, the particle escapes from the trap at lower velocities (30μm/s).

3. PLENUM INTERIOR, SHOWING DRAFT REGULATOR ARRANGEMENT AND STARTER MOTOR. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

3. PLENUM INTERIOR, SHOWING DRAFT REGULATOR ARRANGEMENT AND STARTER MOTOR. - Hot Springs National Park, Bathhouse Row, Lamar Bathhouse: Mechanical & Piping Systems, State Highway 7, 1 mile north of U.S. Highway 70, Hot Springs, Garland County, AR

Effective Elastic Modulus as a Function of Angular Leaf Span for Curved Leaves of Pyrolytic Boron Nitride

NASA Technical Reports Server (NTRS)

Kaforey, M. L.; Deeb, C. W.; Matthiesen, D. H.

1999-01-01

A theoretical equation was derived to predict the spring constant (load/deflection) for a simply supported cylindrical section with a line force applied at the center. Curved leaves of PBN were mechanically deformed and the force versus deflection data was recorded and compared to the derived theoretical equation to yield an effective modulus for each leaf. The effective modulus was found to vary from the pure shear modulus for a flat plate to a mixed mode for a half cylinder as a function of the sine of one half the angular leaf span. The spring constants of individual PBN leaves were usually predicted to within 30%.

A calibration method for the higher modes of a micro-mechanical cantilever

NASA Astrophysics Data System (ADS)

Shatil, N. R.; Homer, M. E.; Picco, L.; Martin, P. G.; Payton, O. D.

2017-05-01

Micro-mechanical cantilevers are increasingly being used as a characterisation tool in both material and biological sciences. New non-destructive applications are being developed that rely on the information encoded within the cantilever's higher oscillatory modes, such as atomic force microscopy techniques that measure the non-topographic properties of a sample. However, these methods require the spring constants of the cantilever at higher modes to be known in order to quantify their results. Here, we show how to calibrate the micro-mechanical cantilever and find the effective spring constant of any mode. The method is uncomplicated to implement, using only the properties of the cantilever and the fundamental mode that are straightforward to measure.

The role of the US Great Plains low-level jet in nocturnal migrant behavior

NASA Astrophysics Data System (ADS)

Wainwright, Charlotte E.; Stepanian, Phillip M.; Horton, Kyle G.

2016-10-01

The movements of aerial animals are under the constant influence of atmospheric flows spanning a range of spatiotemporal scales. The Great Plains nocturnal low-level jet is a large-scale atmospheric phenomenon that provides frequent strong southerly winds through a shallow layer of the airspace. The jet can provide substantial tailwind assistance to spring migrants moving northward, while hindering southward migration during autumn. This atmospheric feature has been suspected to play a prominent role in defining migratory routes, but the flight strategies used with respect to these winds are yet to be examined. Using collocated vertically pointing radar and lidar, we investigate the altitudinal selection behavior of migrants over Oklahoma during two spring and two autumn migration seasons. In general, migrants choose to fly within the jet in spring, often concentrating in the favorable wind speed maximum. Autumn migrants typically fly below the jet, although some will rapidly climb to reach altitudes above the inhibiting winds. The intensity of migration was relatively constant throughout the spring due to the predominantly favorable southerly jet winds. Conversely, autumn migrants were more apt to delay departure to wait for the relatively infrequent northerly winds.

Study of the dynamic properties and effects of temperature using a spring model for the bouncing ball

NASA Astrophysics Data System (ADS)

Wadhwa, Ajay

2013-05-01

We studied the motion of a bouncing ball by representing it through an equivalent mass-spring system executing damped harmonic oscillations. We represented the elasticity of the system through the spring constant ‘k’ and the viscous damping effect, causing loss of energy, through damping constant ‘c’. By including these two factors we formed a differential equation for the equivalent mass-spring system of the bouncing ball. This equation was then solved to study the elastic and dynamic properties of its motion by expressing them in terms of experimentally measurable physical quantities such as contact time, coefficient of restitution, etc. We used our analysis for different types of ball material: rubber (lawn-tennis ball, super ball, soccer ball and squash ball) and plastic (table-tennis ball) at room temperature. Since the effect of temperature on the bounce of a squash ball is significant, we studied the temperature dependence of its elastic properties. The experiments were performed using audio and surface-temperature sensors interfaced with a computer through a USB port. The work presented here is suitable for undergraduate laboratories. It particularly emphasizes the use of computer interfacing for conducting conventional physics experiments.

Extended-range tiltable micromirror

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

Allen, James J; Wiens, Gloria J; Bronson, Jessica R

A tiltable micromirror device is disclosed in which a micromirror is suspended by a progressive linkage with an electrostatic actuator (e.g. a vertical comb actuator or a capacitive plate electrostatic actuator) being located beneath the micromirror. The progressive linkage includes a pair of torsion springs which are connected together to operate similar to a four-bar linkage with spring joints. The progressive linkage provides a non-linear spring constant which can allow the micromirror to be tilted at any angle within its range substantially free from any electrostatic instability or hysteretic behavior.

Localization Algorithm Based on a Spring Model (LASM) for Large Scale Wireless Sensor Networks.

PubMed

Chen, Wanming; Mei, Tao; Meng, Max Q-H; Liang, Huawei; Liu, Yumei; Li, Yangming; Li, Shuai

2008-03-15

A navigation method for a lunar rover based on large scale wireless sensornetworks is proposed. To obtain high navigation accuracy and large exploration area, highnode localization accuracy and large network scale are required. However, thecomputational and communication complexity and time consumption are greatly increasedwith the increase of the network scales. A localization algorithm based on a spring model(LASM) method is proposed to reduce the computational complexity, while maintainingthe localization accuracy in large scale sensor networks. The algorithm simulates thedynamics of physical spring system to estimate the positions of nodes. The sensor nodesare set as particles with masses and connected with neighbor nodes by virtual springs. Thevirtual springs will force the particles move to the original positions, the node positionscorrespondingly, from the randomly set positions. Therefore, a blind node position can bedetermined from the LASM algorithm by calculating the related forces with the neighbornodes. The computational and communication complexity are O(1) for each node, since thenumber of the neighbor nodes does not increase proportionally with the network scale size.Three patches are proposed to avoid local optimization, kick out bad nodes and deal withnode variation. Simulation results show that the computational and communicationcomplexity are almost constant despite of the increase of the network scale size. The time consumption has also been proven to remain almost constant since the calculation steps arealmost unrelated with the network scale size.

Spring plant phenology and false springs in the conterminous US during the 21st century

USGS Publications Warehouse

Allstadt, Andrew J.; Vavrus, Stephen J.; Heglund, Patricia J.; Pidgeon, Anna M.; Thogmartin, Wayne E.; Radeloff, Volker C.

2015-01-01

The onset of spring plant growth has shifted earlier in the year over the past several decades due to rising global temperatures. Earlier spring onset may cause phenological mismatches between the availability of plant resources and dependent animals, and potentially lead to more false springs, when subsequent freezing temperatures damage new plant growth. We used the extended spring indices to project changes in spring onset, defined by leaf out and by first bloom, and predicted false springs until 2100 in the conterminous United States (US) using statistically-downscaled climate projections from the Coupled Model Intercomparison Project 5 ensemble. Averaged over our study region, the median shift in spring onset was 23 days earlier in the Representative Concentration Pathway 8.5 scenario with particularly large shifts in the Western US and the Great Plains. Spatial variation in phenology was due to the influence of short-term temperature changes around the time of spring onset versus season long accumulation of warm temperatures. False spring risk increased in the Great Plains and portions of the Midwest, but remained constant or decreased elsewhere. We conclude that global climate change may have complex and spatially variable effects on spring onset and false springs, making local predictions of change difficult.

Experimental Investigation of a Preloaded Spring-tab Flutter Model

NASA Technical Reports Server (NTRS)

Smith, N H; Clevenson, S A; Barmby, J G

1947-01-01

An experimental investigation was made of a preloaded spring-tab flutter model to determine the effects on flutter speed of aspect ratio, tab frequency, and preloaded spring constant. The rudder was mass-balanced, and the flutter mode studied was essentially one of three degrees of freedom (fin bending coupled with rudder and tab oscillations). Inasmuch as the spring was preloaded, the tab-spring system was a nonlinear one. Frequency of the tab was the most significant parameter in this study, and an increase in flutter speed with increasing frequency is indicated. At a given frequency, the tab of high aspect ratio is shown to have a slightly lower flutter speed than the one of low aspect ratio. Because the frequency of the preloaded spring tab was found to vary radically with amplitude, the flutter speed decreased with increase in initial displacement of the tab.

A spring-mass-damper system dynamics-based driver-vehicle integrated model for representing heterogeneous traffic

NASA Astrophysics Data System (ADS)

Munigety, Caleb Ronald

2018-04-01

The traditional traffic microscopic simulation models consider driver and vehicle as a single unit to represent the movements of drivers in a traffic stream. Due to this very fact, the traditional car-following models have the driver behavior related parameters, but ignore the vehicle related aspects. This approach is appropriate for homogeneous traffic conditions where car is the major vehicle type. However, in heterogeneous traffic conditions where multiple vehicle types are present, it becomes important to incorporate the vehicle related parameters exclusively to account for the varying dynamic and static characteristics. Thus, this paper presents a driver-vehicle integrated model hinged on the principles involved in physics-based spring-mass-damper mechanical system. While the spring constant represents the driver’s aggressiveness, the damping constant and the mass component take care of the stability and size/weight related aspects, respectively. The proposed model when tested, behaved pragmatically in representing the vehicle-type dependent longitudinal movements of vehicles.

Automated Microwave Dielectric Constant Measurement

DTIC Science & Technology

1987-03-01

IJSWC TR 86-46 AD.-A 184 182 AUTOMATED MICROWAVE DIELECTRIC CONSTANT MEASUREMENT SYTIEM BY B. C. GLANCY A. KRALL PESEARCH AND TECHNOLOGY DEPARTMENT...NO0. NO. ACCESSION NO. Silver Spring, Maryland 20903-500061152N ZROO1 ZRO131 R1AA29 11. TITLE (Include Security Classification) AUTOMATED MICROWAVE ...constants as a funct on of microwave frequency has been simplified using an automated testing apparatus. This automated procedure is based on the use of a

A classification of large amplitude oscillations of a spring-pendulum system

NASA Technical Reports Server (NTRS)

Broucke, R.

1977-01-01

We present a detailed classification of large amplitude oscillations of a non-integrable autonomous system with two degrees of freedom: the spring pendulum system. The classification is made with the method of invariant curves. The results show the importance of three types of motion: periodic, quasi-periodic and semi-ergodic. The numerical results are given for nine different values of the energy constant.

Beaver herbivory of willow under two flow regimes: A comparative study on the Green and Yampa rivers

USGS Publications Warehouse

Breck, Stewart W.; Wilson, Kenneth R.; Andersen, Douglas C.

2003-01-01

The effect of flow regulation on plant-herbivore ecology has received very little attention, despite the fact that flow regulation can alter both plant and animal abundance and environmental factors that mediate interactions between them. To determine how regulated flows have impacted beaver (Castor canadensis) and sandbar willow (Salix exigua) ecology, we first quantified the abundance and mapped the spatial distribution of sandbar willow on alluvial sections of the flow-regulated Green River and free-flowing Yampa River in northwestern Colorado. We then established 16 and 15 plots (1 m × 2.7 m) in patches of willow on the Green and Yampa Rivers, respectively, to determine whether rates of beaver herbivory of willow differed between rivers (Green versus Yampa River), seasons (fall-winter versus spring-summer), and years (spring 1998-spring 1999 versus spring 1999-spring 2000). Areal extent of willow was similar on each river, but Green River willow patches were smaller and more numerous. Beavers cut more stems during fall and winter than spring and summer and cut over 6 times more stems (percentage basis) on the Green River than on the Yampa River. We attribute the between-river difference in herbivory to higher availability of willow, greater beaver density, and lower availability of young Fremont cottonwood (Populus deltoides subsp. wislizenii; an alternative food source) on the Green River. Flow regulation increased willow availability to beaver by promoting the formation of island patches that are continuously adjacent to water and feature a perimeter with a relatively high proportion of willow interfacing with water.

Combined pressure regulator and shutoff valve

NASA Technical Reports Server (NTRS)

Koch, E. F. (Inventor)

1974-01-01

A remotely operable pressure regulator and shutoff valve particularly suited for achieving high resolution and flow control, and positive shutoff is described. The valve is characterized by a spring-loaded ball coaxially aligned with a fluid port to be sealed, a spring-loaded pintle extended through the port into engagement with the ball, for controlling the position, a spring-loaded diaphragm for controlling the position of the pintle, and an axially displaceable spring supported by a movable stop which, in turn, is repositioned by a selectively operable stepper motor. Thus, the pressure-response characteristics for the valve can be varied through a selective repositioning of the stop.

The Pneumatic Actuators As Vertical Dynamic Load Simulators On Medium Weighted Wheel Suspension Mechanism

NASA Astrophysics Data System (ADS)

Ka'ka, Simon; Himran, Syukri; Renreng, Ilyas; Sutresman, Onny

2018-02-01

Almost all of road damage can be caused by dynamic loads of vehicles that fluctuate according to the type of vehicle that passes through. This study aims to calculate the vertical dynamic load of the vehicle actually occurs on road construction by the mechanism of vehicle wheel suspension. Pneumatic cylinders driven by pressurized air directly load the spring and shock absorber installed on the wheels of the vehicle. The load fluctuations of the medium weight categorized vehicles are determined by the regulation of the amount of pressurized air that enters into the pneumatic cylinder chamber, pushing the piston and connecting rods. The displacement that occurs during compression on the spring and shock absorber, is substituted into the equation of vehicle dynamic load while taking into account the spring stiffness constant, and the fluid or damper gas coefficient. The results show that the magnitude of the displacement when the compression force works has significant influences to the amount of vertical dynamic load of the vehicle that overlies the road construction. The presence of dynamic load of vehicles that fluctuates and repeats, also affects on the reduction of road ability to receive the load. Experimental results using pneumatic actuators instead of real dynamic vehicle loads illustrate the characteristics of the relationship between work pressure and dynamic load. If the working pressure of P2 (bar) is greater, the vertical dynamic load Ft (N) that overloads the road structure is also greater. The associate graphs show that the shock absorber has a greater ability to reduce dynamic load vertically that burden the road structure when compared with the ability of screw spring.

Fast shuttling of a particle under weak spring-constant noise of the moving trap

NASA Astrophysics Data System (ADS)

Lu, Xiao-Jing; Ruschhaupt, A.; Muga, J. G.

2018-05-01

We investigate the excitation of a quantum particle shuttled in a harmonic trap with weak spring-constant colored noise. The Ornstein-Uhlenbeck model for the noise correlation function describes a wide range of possible noises, in particular for short correlation times the white-noise limit examined by Lu et al. [Phys. Rev. A 89, 063414 (2014)], 10.1103/PhysRevA.89.063414 and, by averaging over correlation times, "1 /f flicker noise." We find expressions for the excitation energy in terms of static (independent of trap motion) and dynamical sensitivities, with opposite behavior with respect to shuttling time, and demonstrate that the excitation can be reduced by proper process timing and design of the trap trajectory.

Analysis of effect of internal and operating variables on performance of SVDS constraint model (ABIND)

NASA Technical Reports Server (NTRS)

Pendergrass, J. R.; Walsh, R. L.

1975-01-01

An examination of the factors which modify the simulation of a constraint in the motion of the aft attach points of the orbiter and external tank during separation has been made. The factors considered were both internal (spring and damper constants) and external (friction coefficient and dynamic pressure). The results show that an acceptable choice of spring/damper constant combinations exist over the expected range of the external factors and that the choice is consistent with a practical integration interval. The constraint model is shown to produce about a 10 percent increase in the relative body pitch angles over the unconstrained case whereas the MDC-STL constraint model is shown to produce about a 38 percent increase.

Slip-Size Distribution and Self-Organized Criticality in Block-Spring Models with Quenched Randomness

NASA Astrophysics Data System (ADS)

Sakaguchi, Hidetsugu; Kadowaki, Shuntaro

2017-07-01

We study slowly pulling block-spring models in random media. Second-order phase transitions exist in a model pulled by a constant force in the case of velocity-strengthening friction. If external forces are slowly increased, nearly critical states are self-organized. Slips of various sizes occur, and the probability distributions of slip size roughly obey power laws. The exponent is close to that in the quenched Edwards-Wilkinson model. Furthermore, the slip-size distributions are investigated in cases of Coulomb friction, velocity-weakening friction, and two-dimensional block-spring models.

Hot embossing and thermal bonding of poly(methyl methacrylate) microfluidic chips using positive temperature coefficient ceramic heater.

PubMed

Wang, Xia; Zhang, Luyan; Chen, Gang

2011-11-01

As a self-regulating heating device, positive temperature coefficient ceramic heater was employed for hot embossing and thermal bonding of poly(methyl methacrylate) microfluidic chip because it supplied constant-temperature heating without electrical control circuits. To emboss a channel plate, a piece of poly(methyl methacrylate) plate was sandwiched between a template and a microscopic glass slide on a positive temperature coefficient ceramic heater. All the assembled components were pressed between two elastic press heads of a spring-driven press while a voltage was applied to the heater for 10 min. Subsequently, the embossed poly(methyl methacrylate) plate bearing negative relief of channel networks was bonded with a piece of poly(methyl methacrylate) cover sheet to obtain a complete microchip using a positive temperature coefficient ceramic heater and a spring-driven press. High quality microfluidic chips fabricated by using the novel embossing/bonding device were successfully applied in the electrophoretic separation of three cations. Positive temperature coefficient ceramic heater indicates great promise for the low-cost production of poly(methyl methacrylate) microchips and should find wide applications in the fabrication of other thermoplastic polymer microfluidic devices.

Spring-mediated distraction enterogenesis in-continuity.

PubMed

Huynh, Nhan; Rouch, Joshua D; Scott, Andrew; Chiang, Elvin; Wu, Benjamin M; Shekherdimian, Shant; Dunn, James C Y

2016-12-01

Distraction enterogenesis has been investigated as a novel treatment for patients with short bowel syndrome (SBS) but has been limited by loss of intestinal length during restoration and need for multiple bowel surgeries. The feasibility of in-continuity, spring-mediated intestinal lengthening has yet to be demonstrated. Juvenile mini-Yucatan pigs underwent in-continuity placement of polycaprolactone (PCL) degradable springs within jejunum. Methods used to anchor the spring ends to the intestine included full-thickness sutures and a high-friction surface spring. Spring constant (k) was 6-15N/m. Bowel was examined for length and presence of spring at 1 to 4weeks. Animals tolerated in-continuity lengthening without bowel obstruction for up to 29days. In-continuity jejunum with springs demonstrated intestinal lengthening by 1.47-fold ±0.11. Five springs had detached prematurely, and lengthening could not be assessed. Histologically, in-continuity jejunum showed significantly increased crypt depth and muscularis thickness in comparison to normal jejunum. Self-expanding endoluminal springs placed in continuity could lengthen intestine without obstruction in a porcine model. This is the first study showing safety and efficacy of a self-expanding endoluminal device for distraction enterogenesis. This is proof-of-concept that in-continuity spring lengthening is feasible and demonstrates its therapeutic potential in SBS. Level 3. Copyright © 2016 Elsevier Inc. All rights reserved.

Method and apparatus for sensing the natural frequency of a cantilevered body

DOEpatents

Duncan, Michael G.

2000-01-01

A method and apparatus for measuring the natural resonant frequency of a spring element by monitoring a phase difference between an output signal from the spring element and an input signal to the spring element and by adjusting frequency of the input signal until a detected phase difference signals that the natural resonant frequency has been reached. The method and apparatus are applied to a micro-cantilevered elements used to measure gas compositions and concentrations. Such elements are provided with coatings that absorb gas to cause deflections and changes in the mass or spring constant of the cantilevered element. These changes correspond to changes in the natural resonant frequency of the cantilevered element which are measured using the method and apparatus described herein.

Phytoplankton bloom dynamics in temperate, turbid, stressed estuaries: a model study

NASA Astrophysics Data System (ADS)

de Swart, Huib E.; Liu, Bo; de Jonge, Victor

2017-04-01

To gain insight into mechanisms underlying phytoplankton bloom dynamics in temperature, turbid estuaries, experiments were conducted with an idealised model that couples physical and biological processes. Results show that the model is capable of producing the main features of the observed blooms in the Ems estuary (Northwest Germany), viz. in the lower reach a spring bloom occur, which is followed by a secondary bloom in autumn. The along-estuary distribution of suspended sediment concentration (SSC) and the along-estuary distance between the nutrient source and the seaward bound of the turbidity zone control both the along-estuary locations and intensities of the blooms. Results of further sensitivity studies reveal that in a shallow, well-mixed estuary, under temporally-constant suspended sediment conditions, the seasonally-varying water temperature has larger impact on the timing of spring blooms than the seasonally-varying incident light intensity. The occurrence of the secondary bloom is caused by the fact that the growth rate of phytoplankton attains a maximum at an optimum water temperature. Bloom intensities are also modulated by the advective processes related to subtidal current because the latter regulates the seaward transport of nutrient from riverine source. Large-scale deepening of navigation channels leads to later spring blooms due to increased mixing depth. Finally, phytoplankton blooms are unlikely to occur in the upper reach due to the elevated SSC and the landward expansion of turbidity zone related to large-scale deepening.

Oscillations studied with the smartphone ambient light sensor

NASA Astrophysics Data System (ADS)

Sans, J. A.; Manjón, F. J.; Pereira, A. L. J.; Gomez-Tejedor, J. A.; Monsoriu, J. A.

2013-11-01

This paper makes use of a smartphone's ambient light sensor to analyse a system of two coupled springs undergoing either simple or damped oscillatory motion. The period, frequency and stiffness of the spring, together with the damping constant and extinction time, are extracted from light intensity curves obtained using a free Android application. The results demonstrate the instructional value of mobile phone sensors as a tool in the physics laboratory.

Design of Ceramic Springs for Use in Semiconductor Crystal Growth in Microgravity

NASA Technical Reports Server (NTRS)

Kaforey, M. F.; Deeb, C. W.; Matthiesen, D. H.

1999-01-01

Segregation studies can be done in microgravity to reduce buoyancy driven convection and investigate diffusion-controlled growth during the growth of semiconductor crystals. During these experiments, it is necessary to prevent free surface formation in order to avoid surface tension driven convection (Marangoni convection). Semiconductor materials such as gallium arsenide and germanium shrink upon melting, so a spring is necessary to reduce the volume of the growth chamber and prevent the formation of a free surface when the sample melts. A spring used in this application must be able to withstand both the high temperature and the processing atmosphere. During the growth of gallium arsenide crystals during the GTE Labs/USAF/NASA GaAs GAS Program and during the CWRU GaAs programs aboard the First and Second United States microgravity Laboratories, springs made of pyrolytic boron nitride (PBN) leaves were used. The mechanical properties of these PBN springs have been investigated and springs having spring constants ranging from 0.25 N/mm to 25 N/mm were measured. With this improved understanding comes the ability to design springs for more general applications, and guidelines are given for optimizing the design of PBN springs for crystal growth applications.

Wide-temperature integrated operational amplifier

NASA Technical Reports Server (NTRS)

Mojarradi, Mohammad (Inventor); Levanas, Greg (Inventor); Chen, Yuan (Inventor); Cozy, Raymond S. (Inventor); Greenwell, Robert (Inventor); Terry, Stephen (Inventor); Blalock, Benjamin J. (Inventor)

2009-01-01

The present invention relates to a reference current circuit. The reference circuit comprises a low-level current bias circuit, a voltage proportional-to-absolute temperature generator for creating a proportional-to-absolute temperature voltage (VPTAT), and a MOSFET-based constant-IC regulator circuit. The MOSFET-based constant-IC regulator circuit includes a constant-IC input and constant-IC output. The constant-IC input is electrically connected with the VPTAT generator such that the voltage proportional-to-absolute temperature is the input into the constant-IC regulator circuit. Thus the constant-IC output maintains the constant-IC ratio across any temperature range.

Constant-Differential-Pressure Two-Fluid Accumulator

NASA Technical Reports Server (NTRS)

Piecuch, Benjamin; Dalton, Luke T.

2010-01-01

A two-fluid accumulator has been designed, built, and demonstrated to provide an acceptably close approximation to constant differential static pressure between two fluids over the full ranges of (1) accumulator stroke, (2) rates of flow of the fluids, and (3) common static pressure applied to the fluids. Prior differential- pressure two-fluid accumulators are generally not capable of maintaining acceptably close approximations to constant differential pressures. The inadequacies of a typical prior differential-pressure two-fluid accumulator can be summarized as follows: The static differential pressure is governed by the intrinsic spring rate (essentially, the stiffness) of an accumulator tank. The spring rate can be tailored through selection of the tank-wall thickness, selection of the number and/or shape of accumulator convolutions, and/or selection of accumulator material(s). Reliance on the intrinsic spring rate of the tank results in three severe limitations: (1) The spring rate and the expulsion efficiency tend to be inversely proportional to each other: that is to say, as the stiffness (and thus the differential pressure) is increased, the range of motion of the accumulator is reduced. (2) As the applied common static pressure increases, the differential pressure tends to decrease. An additional disadvantage, which may or may not be considered limiting, depending on the specific application, is that an increase in stiffness entails an increase in weight. (3) The additional weight required by a low expulsion efficiency accumulator eliminates the advantage given to such gas storage systems. The high expulsion efficiency provided by this two-fluid accumulator allows for a lightweight, tightly packaged system, which can be used in conjunction with a fuel cell-based system.

The effect of muscle stiffness and damping on simulated impact force peaks during running.

PubMed

Nigg, B M; Liu, W

1999-08-01

It has been frequently reported that vertical impact force peaks during running change only minimally when changing the midsole hardness of running shoes. However, the underlying mechanism for these experimental observations is not well understood. An athlete has various possibilities to influence external and internal forces during ground contact (e.g. landing velocity, geometrical alignment, muscle tuning, etc.). The purpose of this study was to discuss one possible strategy to influence external impact forces acting on the athlete's body during running, the strategy to change muscle activity (muscle tuning). The human body was modeled as a simplified mass-spring-damper system. The model included masses of the upper and the lower bodies with each part of the body represented by a rigid and a non-rigid wobbling mass. The influence of mechanical properties of the human body on the vertical impact force peak was examined by varying the spring constants and damping coefficients of the spring-damper units that connected the various masses. Two types of shoe soles were modeled using a non-linear force deformation model with two sets of parameters based on the force-deformation curves of pendulum impact experiments. The simulated results showed that the regulation of the mechanical coupling of rigid and wobbling masses of the human body had an influence on the magnitude of the vertical impact force, but not on its loading rate. It was possible to produce the same impact force peaks altering specific mechanical properties of the system for a soft and a hard shoe sole. This regulation can be achieved through changes of joint angles, changes in joint angular velocities and/or changes in muscle activation levels in the lower extremity. Therefore, it has been concluded that changes in muscle activity (muscle tuning) can be used as a possible strategy to affect vertical impact force peaks during running.

Experimental investigation on the dissipative and elastic characteristics of a yaw colloidal damper destined to carbody suspension of a bullet train

NASA Astrophysics Data System (ADS)

Suciu, B.; Tomioka, T.

2016-09-01

Yaw damper represents a major source of excitation for flexural vibration of the railway carbody. In order to reduce transmissibility of such undesired excitation, yaw damper should allow for large force transmission at low working frequencies, but should behave as vibration isolator at high working frequencies. Unfortunately, the yaw oil damper (OD), which is nowadays in service, has poor intrinsic elastic capabilities and provides damping forces varying as a power function versus the piston speed. Since colloidal damper (CD) has intrinsic elastic capabilities and larger damping forces at lower excitation frequencies, it occurs as an attractive alternative solution to traditional yaw dampers. In this work, a yaw CD destined to carbody suspension of a bullet train was designed and manufactured; then, its dynamic characteristics, produced by both the frictional and colloidal effects, were evaluated from the experimental results, obtained during horizontal vibration tests, performed on a ball-screw shaker. Compared to the corresponding classical yaw OD, the trial yaw CD allowed for: weight reduction of 31.6%; large damping force, dissipated energy and spring constant at long piston stroke under low excitation frequency; low damping force, dissipated energy and spring constant at short piston stroke under high excitation frequency. Elastic properties were justified by introducing a model for the spring constant that included the effect of pore size distribution.

Development of a novel configuration for a MEMS transducer for low bias and high resolution imaging applications

NASA Astrophysics Data System (ADS)

Emadi, Tahereh Arezoo; Buchanan, Douglas A.

2014-03-01

A robust capacitive micromachined ultrasonic transducer has been developed. In this novel configuration, a stack of two deflectable membranes are suspended over a fixed bottom electrode. Similar to conventional capacitive ultrasonic transducers, a generated electrostatic force between the electrodes causes the membranes to deflect and vibrate. However, in this new configuration the transducer effective cavity height is reduced due to the deflection of two membranes. Therefore, the transducer spring constant is more susceptible to bias voltage, which in return reduces the required bias voltage. The transducers have been produced employing a MEMS sacrificial technique where two different membrane anchoring (curved- and flat- anchors) structures, with similar membrane radii were fabricated. Highly doped polysilicon was used as the membrane material. The resonant frequencies of the two transducers have been investigated. It was found that the transducers with curved membrane anchors exhibits a larger resonant frequency shift compared to the transducers with flat membranes for a given bias voltage. Comparison has been made between the spring constant of the flat membrane transducer and that of a conventional single membrane transducer. It is shown that the multiple moving membrane transducer exhibits a larger reduction in the spring constant compared to the conventional transducer, when driven with the same bias voltage. This results in a transducer with a higher power generation capability and sensitivity.

A bead-spring chain as a one-dimensional polyelectrolyte gel.

PubMed

Manning, Gerald S

2018-05-23

The physical principles underlying expansion of a single-chain polyelectrolyte coil caused by Coulomb repulsions among its ionized groups, and the expansion of a cross-linked polyelectrolyte gel, are probably the same. In this paper, we analyze a "one-dimensional" version of a gel, namely, a linear chain of charged beads connected by Hooke's law springs. In the Debye-Hückel range of relatively weak Coulomb strength, where counterion condensation does not occur, the springs are realistically stretched on a nanolength scale by the repulsive interactions among the beads, if we use a spring constant normalized by the inverse square of the solvent Bjerrum length. The persistence length and radius of gyration counter-intuitively decrease when Coulomb strength is increased, if analyzed in the framework of an OSF-type theory; however, a buckling theory generates the increase that is consistent with bead-spring simulations.

Springs of Florida

USGS Publications Warehouse

Rosenau, Jack C.; Faulkner, Glen L.; Hendry, Charles W.; Hull, Robert W.

1977-01-01

The first comprehensive report of Florida's springs, which contains both a story of the springs and a collection of facts about them, was published thirty years ago (Ferguson and others, 1947). Since then, much additional data on springs have been gathered and the current report, Springs of Florida, makes a wealth of information on springs available to the public. Springs of Florida, prepared by the U.S. Geological Survey in cooperation with the Bureau of Geology, Florida Department of Natural Resources, publishers, and the Bureau of Water Resources Management, Florida Department of Environmental Regulation, is intended to provide sufficient background information for a lucid understanding of the nature and occurrence of the springs in the State.

hsp90 and hsp47 appear to play an important role in minnow Puntius sophore for surviving in the hot spring run-off aquatic ecosystem.

PubMed

Mahanty, Arabinda; Purohit, Gopal Krishna; Yadav, Ravi Prakash; Mohanty, Sasmita; Mohanty, Bimal Prasanna

2017-02-01

Changes in the expression of a number of hsp genes in minnow Puntius sophore collected from a hot spring run-off (Atri hot spring in Odisha, India; 20 o 09'N 85 ° 18'E, 36-38 °C) were investigated to study the upper thermal acclimation response under heat stress, using same species from aquaculture ponds (water temperature 27 °C) as control. Expression of hsp genes was analyzed in both groups using RT-qPCR, which showed up-regulation of hsp90 (2.1-fold) and hsp47 (2.5-fold) in hot spring run-off fishes, whereas there was no alteration in expression of other hsps. As the fish inhabit the hot spring run-off area for very long duration, they could have adapted to the environment. To test this hypothesis, fishes collected from hot spring run-off were divided into two groups; one was heat-shocked at 41 °C/24 h, and the other was acclimatized at 27 °C/24 h. Up-regulation of all the hsps (except hsp78) was observed in the heat-shocked fishes, whereas expression of all hsps was found to be down-regulated to the basal level in fishes maintained at 27 °C/24 h. Pathway analysis showed that the expressions of all the hsps except hsp90 are regulated by the transcription factor heat shock factor 1 (Hsf1). This study showed that hsp90 and hsp47 play an important role in Puntius sophore for surviving in the high-temperature environment of the hot spring run-off. Additionally, we show that plasticity in hsp gene expression is not lost in the hot spring run-off population.

40 CFR 49.11071 - Identification of plan.

Code of Federal Regulations, 2011 CFR

2011-07-01

... Implementation Plan for the Confederated Tribes of the Warm Springs Reservation of Oregon § 49.11071... Confederated Tribes of the Warm Springs Reservation. This plan consists of a combination of Tribal rules and measures and Federal regulations and measures which apply within the Warm Springs Reservation. ...

40 CFR 49.11071 - Identification of plan.

Code of Federal Regulations, 2014 CFR

2014-07-01

... Implementation Plan for the Confederated Tribes of the Warm Springs Reservation of Oregon § 49.11071... Confederated Tribes of the Warm Springs Reservation. This plan consists of a combination of Tribal rules and measures and Federal regulations and measures which apply within the Warm Springs Reservation. ...

40 CFR 49.11071 - Identification of plan.

Code of Federal Regulations, 2010 CFR

2010-07-01

... the Confederated Tribes of the Warm Springs Reservation of Oregon § 49.11071 Identification of plan... Tribes of the Warm Springs Reservation. This plan consists of a combination of Tribal rules and measures and Federal regulations and measures which apply within the Warm Springs Reservation. ...

40 CFR 49.11071 - Identification of plan.

Code of Federal Regulations, 2012 CFR

2012-07-01

... Implementation Plan for the Confederated Tribes of the Warm Springs Reservation of Oregon § 49.11071... Confederated Tribes of the Warm Springs Reservation. This plan consists of a combination of Tribal rules and measures and Federal regulations and measures which apply within the Warm Springs Reservation. ...

40 CFR 49.11071 - Identification of plan.

Code of Federal Regulations, 2013 CFR

2013-07-01

... Implementation Plan for the Confederated Tribes of the Warm Springs Reservation of Oregon § 49.11071... Confederated Tribes of the Warm Springs Reservation. This plan consists of a combination of Tribal rules and measures and Federal regulations and measures which apply within the Warm Springs Reservation. ...

The RING Finger E3 Ligase SpRing is a Positive Regulator of Salt Stress Signaling in Salt-Tolerant Wild Tomato Species.

PubMed

Qi, Shilian; Lin, Qingfang; Zhu, Huishan; Gao, Fenghua; Zhang, Wenhao; Hua, Xuejun

2016-03-01

Protein ubiquitination in plants plays critical roles in many biological processes, including adaptation to abiotic stresses. Previously, RING finger E3 ligase has been characterized during salt stress response in several plant species, but little is known about its function in tomato. Here, we report that SpRing, a stress-inducible gene, is involved in salt stress signaling in wild tomato species Solanum pimpinellifolium 'PI365967'. In vitro ubiquitination assay revealed that SpRing is an E3 ubiquitin ligase and the RING finger conserved region is required for its activity. SpRing is expressed in all tissues of wild tomato and up-regulated by salt, drought and osmotic stresses, but repressed by low temperature. Green fluorescent protein (GFP) fusion analysis showed that SpRing is localized at the endoplasmic reticulum. Silencing of SpRing through a virus-induced gene silencing approach led to increased sensitivity to salt stress in wild tomato. Overexpression of SpRing in Arabidopsis thaliana resulted in enhanced salt tolerance during seed germination and early seedling development. The expression levels of certain key stress-related genes are altered both in SpRing-overexpressing Arabidopsis plants and virus-induced gene silenced tomato seedlings. Taken together, our results indicate that SpRing is involved in salt stress and functions as a positive regulator of salt tolerance. © The Author 2016. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

33 CFR 117.202 - Cold Spring Brook.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Cold Spring Brook. 117.202 Section 117.202 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Connecticut § 117.202 Cold Spring Brook. The draw of...

33 CFR 117.202 - Cold Spring Brook.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Cold Spring Brook. 117.202 Section 117.202 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Connecticut § 117.202 Cold Spring Brook. The draw of...

33 CFR 117.202 - Cold Spring Brook.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Cold Spring Brook. 117.202 Section 117.202 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Connecticut § 117.202 Cold Spring Brook. The draw of...

33 CFR 117.202 - Cold Spring Brook.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Cold Spring Brook. 117.202 Section 117.202 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Connecticut § 117.202 Cold Spring Brook. The draw of...

33 CFR 117.202 - Cold Spring Brook.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Cold Spring Brook. 117.202 Section 117.202 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Connecticut § 117.202 Cold Spring Brook. The draw of...

Using AFM Force Curves to Explore Properties of Elastomers

ERIC Educational Resources Information Center

Ferguson, Megan A.; Kozlowski, Joseph J.

2013-01-01

polydimethylsiloxane (PDMS) elastomers. Force curves are used to quantify the stiffness of elastomers prepared with different base-to-curing agent ratios. Trends in observed spring constants of the…

36 CFR 21.3 - Use of thermal water.

Code of Federal Regulations, 2010 CFR

2010-07-01

... SPRINGS NATIONAL PARK; BATHHOUSE REGULATIONS § 21.3 Use of thermal water. (a) The use of the thermal waters of Hot Springs National Park, for purposes other than those authorized by the Superintendent, is... Springs National Park is prohibited. (c) The introduction of any substance, chemical, or other material or...

36 CFR 21.3 - Use of thermal water.

Code of Federal Regulations, 2011 CFR

2011-07-01

... SPRINGS NATIONAL PARK; BATHHOUSE REGULATIONS § 21.3 Use of thermal water. (a) The use of the thermal waters of Hot Springs National Park, for purposes other than those authorized by the Superintendent, is... Springs National Park is prohibited. (c) The introduction of any substance, chemical, or other material or...

Muscle-spring dynamics in time-limited, elastic movements.

PubMed

Rosario, M V; Sutton, G P; Patek, S N; Sawicki, G S

2016-09-14

Muscle contractions that load in-series springs with slow speed over a long duration do maximal work and store the most elastic energy. However, time constraints, such as those experienced during escape and predation behaviours, may prevent animals from achieving maximal force capacity from their muscles during spring-loading. Here, we ask whether animals that have limited time for elastic energy storage operate with springs that are tuned to submaximal force production. To answer this question, we used a dynamic model of a muscle-spring system undergoing a fixed-end contraction, with parameters from a time-limited spring-loader (bullfrog: Lithobates catesbeiana) and a non-time-limited spring-loader (grasshopper: Schistocerca gregaria). We found that when muscles have less time to contract, stored elastic energy is maximized with lower spring stiffness (quantified as spring constant). The spring stiffness measured in bullfrog tendons permitted less elastic energy storage than was predicted by a modelled, maximal muscle contraction. However, when muscle contractions were modelled using biologically relevant loading times for bullfrog jumps (50 ms), tendon stiffness actually maximized elastic energy storage. In contrast, grasshoppers, which are not time limited, exhibited spring stiffness that maximized elastic energy storage when modelled with a maximal muscle contraction. These findings demonstrate the significance of evolutionary variation in tendon and apodeme properties to realistic jumping contexts as well as the importance of considering the effect of muscle dynamics and behavioural constraints on energy storage in muscle-spring systems. © 2016 The Author(s).

Errors in the determination of the solar constant by the Langley method due to the presence of volcanic aerosol

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

Schotland, R.M.; Hartman, J.E.

1989-02-01

The accuracy in the determination of the solar constant by means of the Langley method is strongly influenced by the spatial inhomogeneities of the atmospheric aerosol. Volcanos frequently inject aerosol into the upper troposphere and lower stratosphere. This paper evaluates the solar constant error that would occur if observations had been taken throughout the plume of El Chichon observed by NASA aircraft in the fall of 1982 and the spring of 1983. A lidar method is suggested to minimize this error. 15 refs.

Molecular screening of the Hbs Constant Spring (codon 142, TAA>CAA, α2) and Paksé (codon 142, TAA>TAT, α2) mutations in Thailand.

PubMed

Pichanun, Dalad; Munkongdee, Thongperm; Klamchuen, Sumonmaln; Butthep, Punnee; Winichagoon, Pranee; Fucharoen, Suthat; Svasti, Saovaros

2010-01-01

Hb Constant Spring [Hb CS, α142(H19)Term] and Hb Paksé [α142(H19)Term] occur from the mutation in the termination codon of the α2-globin gene, TAA>CAA (→Gln) and TAA>TAT (→Tyr), respectively. They are the most common nondeletional α-thalassemia (α-thal) variants causing Hb H disease in Southeast Asia. In this study, 587 cord blood samples were screened for the Hb CS and Hb Paksé mutations by a dot-blot hybridization technique using oligonucleotide probes specific for each mutation. The results showed that the prevalence of Hb CS and Hb Paksé in Central Thailand are 5.80 and 0.51%, respectively, which is in concordance with the results from previous studies.

Fore and aft elastic response characteristics of size 34x9.9, type 7, 14 ply-rated aircraft tires of bias ply, bias belted, and radial belted design. M.S. Thesis - George Washington Univ., Washington, D. C.

NASA Technical Reports Server (NTRS)

Tanner, J. A.

1973-01-01

An investigation was conducted to determine the fore-and-aft elastic response characteristics of aircraft tires of bias ply, bias-belted, and radial-belted design. The investigation consisted of: (1)static and rolling tests, (2)a statistical analysis which related the measured tire elastic characteristics to variations in the vertical load, inflation pressure, braking force and/or tire vertical deflection, and (3) a semi-empirical analysis which related the tire elastic behavior to measured wheel slippage during a steady-state braking. The results of this investigation indicate that the bias-belted tire has the largest spring constant value for most loading conditions and the radial-belted tire has the smallest spring constant value.

36 CFR 7.18 - Hot Springs National Park.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Hot Springs National Park. 7.18 Section 7.18 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.18 Hot Springs National Park. (a) Commercial...

36 CFR 7.18 - Hot Springs National Park.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 36 Parks, Forests, and Public Property 1 2011-07-01 2011-07-01 false Hot Springs National Park. 7.18 Section 7.18 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.18 Hot Springs National Park. (a) Commercial...

36 CFR 7.18 - Hot Springs National Park.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 36 Parks, Forests, and Public Property 1 2012-07-01 2012-07-01 false Hot Springs National Park. 7.18 Section 7.18 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.18 Hot Springs National Park. (a) Commercial...

36 CFR 7.18 - Hot Springs National Park.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 36 Parks, Forests, and Public Property 1 2014-07-01 2014-07-01 false Hot Springs National Park. 7.18 Section 7.18 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.18 Hot Springs National Park. (a) Commercial...

36 CFR 7.18 - Hot Springs National Park.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 36 Parks, Forests, and Public Property 1 2013-07-01 2013-07-01 false Hot Springs National Park. 7.18 Section 7.18 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.18 Hot Springs National Park. (a) Commercial...

Fault stability under conditions of variable normal stress

USGS Publications Warehouse

Dieterich, J.H.; Linker, M.F.

1992-01-01

The stability of fault slip under conditions of varying normal stress is modelled as a spring and slider system with rate- and state-dependent friction. Coupling of normal stress to shear stress is achieved by inclining the spring at an angle, ??, to the sliding surface. Linear analysis yields two conditions for unstable slip. The first, of a type previously identified for constant normal stress systems, results in instability if stiffness is below a critical value. Critical stiffness depends on normal stress, constitutive parameters, characteristic sliding distance and the spring angle. Instability of the first type is possible only for velocity-weakening friction. The second condition yields instability if spring angle ?? <-cot-1??ss, where ??ss is steady-state sliding friction. The second condition can arise under conditions of velocity strengthening or weakening. Stability fields for finite perturbations are investigated by numerical simulation. -Authors

Nonhydrodynamic Characteristics of the Oscillating Screen Viscometer

NASA Technical Reports Server (NTRS)

Berg, Robert F.; Moldover, Michael R.

1993-01-01

Extraction of the viscosity from the oscillating screen's response function requires knowledge of it resonance frequency omega(sub 0) and of the prefactor k(sub tr)/k(theta), where k(sub tr) is a transducer coefficient and k(sub theta) is the torsion spring constant. The determination of these parameters is described. The effect of a possible anomaly in the dielectric constant near the critical point of xenon will be negligible.

Flows in forward deformable roll coating gaps: Comparison between spring and plane-strain models of roll cover

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

Carvalho, M.S.; Scriven, L.E.

1997-12-01

In this report the flow between rigid and a deformable rotating rolls fully submerged in a liquid pool is studied. The deformation of compliant roll cover is described by two different models (1) independent, radially oriented springs that deform in response to the traction force applied at the extremity of each or one-dimensional model, and (2) a plane-strain deformation of an incompressible Mooney-Rivlin material or non-linear elastic model. Based on the flow rate predictions of both models, an empirical relation between the spring constant of the one dimensional model and the roll cover thickness and elastic modulus is proposed.

Simple Harmonics Motion experiment based on LabVIEW interface for Arduino

NASA Astrophysics Data System (ADS)

Tong-on, Anusorn; Saphet, Parinya; Thepnurat, Meechai

2017-09-01

In this work, we developed an affordable modern innovative physics lab apparatus. The ultrasonic sensor is used to measure the position of a mass attached on a spring as a function of time. The data acquisition system and control device were developed based on LabVIEW interface for Arduino UNO R3. The experiment was designed to explain wave propagation which is modeled by simple harmonic motion. The simple harmonic system (mass and spring) was observed and the motion can be realized using curve fitting to the wave equation in Mathematica. We found that the spring constants provided by Hooke’s law and the wave equation fit are 9.9402 and 9.1706 N/m, respectively.

36 CFR 21.4 - Registration of physicians.

Code of Federal Regulations, 2013 CFR

2013-07-01

... INTERIOR HOT SPRINGS NATIONAL PARK; BATHHOUSE REGULATIONS § 21.4 Registration of physicians. Physicians desiring to prescribe the thermal waters of Hot Springs National Park must first be registered at the...

36 CFR 21.4 - Registration of physicians.

Code of Federal Regulations, 2012 CFR

2012-07-01

... INTERIOR HOT SPRINGS NATIONAL PARK; BATHHOUSE REGULATIONS § 21.4 Registration of physicians. Physicians desiring to prescribe the thermal waters of Hot Springs National Park must first be registered at the...

36 CFR 21.4 - Registration of physicians.

Code of Federal Regulations, 2011 CFR

2011-07-01

... INTERIOR HOT SPRINGS NATIONAL PARK; BATHHOUSE REGULATIONS § 21.4 Registration of physicians. Physicians desiring to prescribe the thermal waters of Hot Springs National Park must first be registered at the...

36 CFR 21.4 - Registration of physicians.

Code of Federal Regulations, 2014 CFR

2014-07-01

... INTERIOR HOT SPRINGS NATIONAL PARK; BATHHOUSE REGULATIONS § 21.4 Registration of physicians. Physicians desiring to prescribe the thermal waters of Hot Springs National Park must first be registered at the...

36 CFR 21.4 - Registration of physicians.

Code of Federal Regulations, 2010 CFR

2010-07-01

... INTERIOR HOT SPRINGS NATIONAL PARK; BATHHOUSE REGULATIONS § 21.4 Registration of physicians. Physicians desiring to prescribe the thermal waters of Hot Springs National Park must first be registered at the...

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

Benedek, George; Casparay, Alfred H.

In this project, we are developing a new system for measuring forces within and between nanoscale biological molecules based on mesoscopic springs made of cholesterol helical ribbons. These ribbons self-assemble in a wide variety of complex fluids containing sterol, a mixture of surfactants and water [1] and have spring constants in the range from 0.5 to 500 pN/nm [2-4]. By the end of this project, we have demonstrated that the cholesterol helical ribbons can be used for measuring forces between biological objects and for mapping the strain fields in hydrogels.

Optimal Design of Spring Characteristics of Damper for Subharmonic Vibration in Automatic Transmission Powertrain

NASA Astrophysics Data System (ADS)

Nakae, T.; Ryu, T.; Matsuzaki, K.; Rosbi, S.; Sueoka, A.; Takikawa, Y.; Ooi, Y.

2016-09-01

In the torque converter, the damper of the lock-up clutch is used to effectively absorb the torsional vibration. The damper is designed using a piecewise-linear spring with three stiffness stages. However, a nonlinear vibration, referred to as a subharmonic vibration of order 1/2, occurred around the switching point in the piecewise-linear restoring torque characteristics because of the nonlinearity. In the present study, we analyze vibration reduction for subharmonic vibration. The model used herein includes the torque converter, the gear train, and the differential gear. The damper is modeled by a nonlinear rotational spring of the piecewise-linear spring. We focus on the optimum design of the spring characteristics of the damper in order to suppress the subharmonic vibration. A piecewise-linear spring with five stiffness stages is proposed, and the effect of the distance between switching points on the subharmonic vibration is investigated. The results of our analysis indicate that the subharmonic vibration can be suppressed by designing a damper with five stiffness stages to have a small spring constant ratio between the neighboring springs. The distances between switching points must be designed to be large enough that the amplitude of the main frequency component of the systems does not reach the neighboring switching point.

Direct current force sensing device based on compressive spring, permanent magnet, and coil-wound magnetostrictive/piezoelectric laminate.

PubMed

Leung, Chung Ming; Or, Siu Wing; Ho, S L

2013-12-01

A force sensing device capable of sensing dc (or static) compressive forces is developed based on a NAS106N stainless steel compressive spring, a sintered NdFeB permanent magnet, and a coil-wound Tb(0.3)Dy(0.7)Fe(1.92)/Pb(Zr, Ti)O3 magnetostrictive∕piezoelectric laminate. The dc compressive force sensing in the device is evaluated theoretically and experimentally and is found to originate from a unique force-induced, position-dependent, current-driven dc magnetoelectric effect. The sensitivity of the device can be increased by increasing the spring constant of the compressive spring, the size of the permanent magnet, and/or the driving current for the coil-wound laminate. Devices of low-force (20 N) and high-force (200 N) types, showing high output voltages of 262 and 128 mV peak, respectively, are demonstrated at a low driving current of 100 mA peak by using different combinations of compressive spring and permanent magnet.

Relation between flow and temporal variations of nitrate and pesticides in two karst springs in northern Alabama

USGS Publications Warehouse

Kingsbury, J.A.

2008-01-01

Two karst springs in the Mississippian Carbonate Aquifer of northern Alabama were sampled between March 1999 and March 2001 to characterize the variability in concentration of nitrate, pesticides, selected pesticide degradates, water temperature, and inorganic constituents. Water temperature and inorganic ion data for McGeehee Spring indicate that this spring represents a shallow flow system with a relatively short average ground-water residence time. Water issuing from the larger of the two springs, Meridianville Spring, maintained a constant temperature, and inorganic ion data indicate that this water represents a deeper flow system having a longer average ground-water residence time than McGeehee Spring. Although water-quality data indicate differing short-term responses to rainfall at the two springs, the seasonal variation of nitrate and pesticide concentrations generally is similar for the two springs. With the exception of pesticides detected at low concentrations, the coefficient of variation for most constituent concentrations was less than that of flow at both springs, with greater variability in concentration at McGeehee Spring. Degradates of the herbicides atrazine and fluometuron were detected at concentrations comparable to or greater than the parent pesticides. Decreases in concentration of the principal degradate of fluometuron from about July to November indicate that the degradation rate may decrease as fluometuron (demethylfluometuron) moves deeper into the soil after application. Data collected during the study show that from about November to March when recharge rates increase, nitrate and residual pesticides in the soil, unsaturated zone, and storage within the aquifer are transported to the spring discharges. Because of the increase in recharge, fluometuron loads discharged from the springs during the winter were comparable to loads discharged at the springs during the growing season. ?? 2008 American Water Resources Association.

77 FR 35617 - Amendment of Class C Airspace; Colorado Springs, CO

Federal Register 2010, 2011, 2012, 2013, 2014

2012-06-14

... 44 U.S.C. 1510. #0; #0;The Code of Federal Regulations is sold by the Superintendent of Documents. #0...; Airspace Docket No. 12-AWA-4] Amendment of Class C Airspace; Colorado Springs, CO AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule. SUMMARY: This action modifies the Colorado Springs, CO, Class C...

A piecewise mass-spring-damper model of the human breast.

PubMed

Cai, Yiqing; Chen, Lihua; Yu, Winnie; Zhou, Jie; Wan, Frances; Suh, Minyoung; Chow, Daniel Hung-Kay

2018-01-23

Previous models to predict breast movement whilst performing physical activities have, erroneously, assumed uniform elasticity within the breast. Consequently, the predicted displacements have not yet been satisfactorily validated. In this study, real time motion capture of the natural vibrations of a breast that followed, after raising and allowing it to fall freely, revealed an obvious difference in the vibration characteristics above and below the static equilibrium position. This implied that the elastic and viscous damping properties of a breast could vary under extension or compression. Therefore, a new piecewise mass-spring-damper model of a breast was developed with theoretical equations to derive values for its spring constants and damping coefficients from free-falling breast experiments. The effective breast mass was estimated from the breast volume extracted from a 3D body scanned image. The derived spring constant (k a  = 73.5 N m -1 ) above the static equilibrium position was significantly smaller than that below it (k b  = 658 N m -1 ), whereas the respective damping coefficients were similar (c a  = 1.83 N s m -1 , c b  = 2.07 N s m -1 ). These values were used to predict the nipple displacement during bare-breasted running for validation. The predicted and experimental results had a 2.6% or less root-mean-square-error of the theoretical and experimental amplitudes, so the piecewise mass-spring-damper model and equations were considered to have been successfully validated. This provides a theoretical basis for further research into the dynamic, nonlinear viscoelastic properties of different breasts and the prediction of external forces for the necessary breast support during different sports activities. Copyright © 2017 Elsevier Ltd. All rights reserved.

Educators' emotion regulation strategies and their physiological indicators of chronic stress over 1 year.

PubMed

Katz, Deirdre A; Harris, Alexis; Abenavoli, Rachel; Greenberg, Mark T; Jennings, Patricia A

2018-04-01

Studies show teaching is a highly stressful profession and that chronic work stress is associated with adverse health outcomes. This study analysed physiological markers of stress and self-reported emotion regulation strategies in a group of middle school teachers over 1 year. Chronic physiological stress was assessed with diurnal cortisol measures at three time points over 1 year (fall, spring, fall). The aim of this longitudinal study was to investigate the changes in educators' physiological level of stress. Results indicate that compared to those in the fall, cortisol awakening responses were blunted in the spring. Further, this effect was ameliorated by the summer break. Additionally, self-reported use of the emotion regulation strategy reappraisal buffered the observed blunting that occurred in the spring. Copyright © 2017 John Wiley & Sons, Ltd.

Effect of temperature on the orthodontic clinical applications of niti closed-coil springs

PubMed Central

Espinar-Escalona, Eduardo; Llamas-Carreras, José M.; Barrera-Mora, José M.; Abalos-Lasbrucci, Camilo

2013-01-01

NiTi spring coils were used to obtain large deformation under a constant force. The device consists on a NiTi coil spring, superelastic at body temperature, in order to have a stress plateau during the austenitic retransformation during the unloading. The temperature variations induced changes in the spring force. Objectives: The aim of this study is to investigate the effect of the temperature variations in the spring forces and corrosion behaviour simulating the ingestion hot/cold drinks and food. Study Design: The springs were subjected to a tensile force using universal testing machine MTS-Adamel (100 N load cell). All tests were performed in artificial saliva maintained at different temperatures. The corrosion tests were performed according to the ISO-standard 10993-15:2000. Results: The increase in temperature of 18oC induced an increase in the spring force of 30%. However, when the temperature returns to 37oC the distraction force recovers near the initial level. After cooling down the spring to 15oC, the force decreased by 46%. This investigation show as the temperature increase, the corrosion potential shifts towards negative values and the corrosion density is rising. Conclusions: The changes of the temperatures do not modify the superelastic behaviour of the NiTi closed-coil springs. The corrosion potential of NiTi in artificial saliva is decreasing by the rise of the temperatures. Key words:Superelasticity, NiTi, springs, orthodontic, coils, recovery, temperature. PMID:23722142

Noninvasive determination of optical lever sensitivity in atomic force microscopy

NASA Astrophysics Data System (ADS)

Higgins, M. J.; Proksch, R.; Sader, J. E.; Polcik, M.; Mc Endoo, S.; Cleveland, J. P.; Jarvis, S. P.

2006-01-01

Atomic force microscopes typically require knowledge of the cantilever spring constant and optical lever sensitivity in order to accurately determine the force from the cantilever deflection. In this study, we investigate a technique to calibrate the optical lever sensitivity of rectangular cantilevers that does not require contact to be made with a surface. This noncontact approach utilizes the method of Sader et al. [Rev. Sci. Instrum. 70, 3967 (1999)] to calibrate the spring constant of the cantilever in combination with the equipartition theorem [J. L. Hutter and J. Bechhoefer, Rev. Sci. Instrum. 64, 1868 (1993)] to determine the optical lever sensitivity. A comparison is presented between sensitivity values obtained from conventional static mode force curves and those derived using this noncontact approach for a range of different cantilevers in air and liquid. These measurements indicate that the method offers a quick, alternative approach for the calibration of the optical lever sensitivity.

Changes in leg spring behaviour, plantar loading and foot mobility magnitude induced by an exhaustive treadmill run in adolescent middle-distance runners.

PubMed

Fourchet, François; Girard, Olivier; Kelly, Luke; Horobeanu, Cosmin; Millet, Grégoire P

2015-03-01

This study aimed to determine adjustments in spring-mass model characteristics, plantar loading and foot mobility induced by an exhaustive run. Within-participants repeated measures. Eleven highly-trained adolescent middle-distance runners ran to exhaustion on a treadmill at a constant velocity corresponding to 95% of velocity associated with VO₂max (17.8 ± 1.4 kmh(-1), time to exhaustion=8.8 ± 3.4 min). Contact time obtained from plantar pressure sensors was used to estimate spring-mass model characteristics, which were recorded (during 30 s) 1 min after the start and prior to exhaustion using pressure insoles. Foot mobility magnitude (a composite measure of vertical and medial-lateral mobility of the midfoot) was measured before and after the run. Mean contact area (foot to ground), contact time, peak vertical ground reaction force, centre of mass vertical displacement and leg compression increased significantly with fatigue, while flight time, leg stiffness and mean pressure decreased. Leg stiffness decreased because leg compression increased to a larger extent than peak vertical ground reaction forces. Step length, step frequency and foot mobility magnitude did not change at exhaustion. The stride pattern of adolescents when running on a treadmill at high constant velocity deteriorates near exhaustion, as evidenced by impaired leg-spring behaviour (leg stiffness) and altered plantar loading. Copyright © 2014 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Modeling and performance improvement of the constant power regulator systems in variable displacement axial piston pump.

PubMed

Park, Sung Hwan; Lee, Ji Min; Kim, Jong Shik

2013-01-01

An irregular performance of a mechanical-type constant power regulator is considered. In order to find the cause of an irregular discharge flow at the cut-off pressure area, modeling and numerical simulations are performed to observe dynamic behavior of internal parts of the constant power regulator system for a swashplate-type axial piston pump. The commercial numerical simulation software AMESim is applied to model the mechanical-type regulator with hydraulic pump and simulate the performance of it. The validity of the simulation model of the constant power regulator system is verified by comparing simulation results with experiments. In order to find the cause of the irregular performance of the mechanical-type constant power regulator system, the behavior of main components such as the spool, sleeve, and counterbalance piston is investigated using computer simulation. The shape modification of the counterbalance piston is proposed to improve the undesirable performance of the mechanical-type constant power regulator. The performance improvement is verified by computer simulation using AMESim software.

Mechanical energy absorber

NASA Technical Reports Server (NTRS)

Wesselski, Clarence J. (Inventor)

1993-01-01

An energy absorbing system for controlling the force where a moving object engages a stationary stop and where the system utilized telescopic tubular members, energy absorbing diaphragm elements, force regulating disc springs, and a return spring to return the telescoping member to its start position after stroking is presented. The energy absorbing system has frusto-conical diaphragm elements frictionally engaging the shaft and are opposed by a force regulating set of disc springs. In principle, this force feedback mechanism serves to keep the stroking load at a reasonable level even if the friction coefficient increases greatly. This force feedback device also serves to desensitize the singular and combined effects of manufacturing tolerances, sliding surface wear, temperature changes, dynamic effects, and lubricity.

Engineered elastomeric proteins with dual elasticity can be controlled by a molecular regulator.

PubMed

Cao, Yi; Li, Hongbin

2008-08-01

Elastomeric proteins are molecular springs that confer excellent mechanical properties to many biological tissues and biomaterials. Depending on the role performed by the tissue or biomaterial, elastomeric proteins can behave as molecular springs or shock absorbers. Here we combine single-molecule atomic force microscopy and protein engineering techniques to create elastomeric proteins that can switch between two distinct types of mechanical behaviour in response to the binding of a molecular regulator. The proteins are mechanically labile by design and behave as entropic springs with an elasticity that is governed by their configurational entropy. However, when a molecular regulator binds to the protein, it switches into a mechanically stable state and can act as a shock absorber. These engineered proteins effectively mimic and combine the two extreme forms of elastic behaviour found in natural elastomeric proteins, and thus represent a new type of smart nanomaterial that will find potential applications in nanomechanics and material sciences.

Working Ni-Mn-Ga Single Crystals in a Magnetic Field Against a Spring Load

NASA Astrophysics Data System (ADS)

Lindquist, P. G.; Müllner, P.

2015-03-01

This research characterizes ferromagnetic shape memory elements for use as mechanical actuators. A single crystal of Ni-Mn-Ga was pre-strained in compression from 0 to 6 % and then the shape was recovered with a magnetic field perpendicular to the loading direction while working against a pair of springs. The magnetic field was raised from 0 to 0.64 MA/m and then reduced to zero field. Eight pairs of springs with combined spring constants ranging from 14.3 to 269.4 N/mm were used. When the magnetic field was on, the sample expanded against the springs due to magnetic field-induced strain. When the magnetic field was turned off, the springs compressed the sample back to the initial size before the next cycle. During each cycle, force and displacement were measured and the specific work was computed. Specific work increased with the applied magnetic field and the pre-strain, with a maximum of 14 kJ/m3 at 4.5 % pre-strain and 0.64 MA/m. This value is five times less than the values suggested in the literature which were inferred from stress-strain curves measured under various magnetic fields. The spring prescribes the load-displacement path of the magnetic shape memory element and controls the work output of the actuator.

Human hopping on damped surfaces: strategies for adjusting leg mechanics.

PubMed

Moritz, Chet T; Farley, Claire T

2003-08-22

Fast-moving legged animals bounce along the ground with spring-like legs and agilely traverse variable terrain. Previous research has shown that hopping and running humans maintain the same bouncing movement of the body's centre of mass on a range of elastic surfaces by adjusting their spring-like legs to exactly offset changes in surface stiffness. This study investigated human hopping on damped surfaces that dissipated up to 72% of the hopper's mechanical energy. On these surfaces, the legs did not act like pure springs. Leg muscles performed up to 24-fold more net work to replace the energy lost by the damped surface. However, considering the leg and surface together, the combination appeared to behave like a constant stiffness spring on all damped surfaces. By conserving the mechanics of the leg-surface combination regardless of surface damping, hoppers also conserved centre-of-mass motions. Thus, the normal bouncing movements of the centre of mass in hopping are not always a direct result of spring-like leg behaviour. Conserving the trajectory of the centre of mass by maintaining spring-like mechanics of the leg-surface combination may be an important control strategy for fast-legged locomotion on variable terrain.

Human hopping on damped surfaces: strategies for adjusting leg mechanics.

PubMed Central

Moritz, Chet T; Farley, Claire T

2003-01-01

Fast-moving legged animals bounce along the ground with spring-like legs and agilely traverse variable terrain. Previous research has shown that hopping and running humans maintain the same bouncing movement of the body's centre of mass on a range of elastic surfaces by adjusting their spring-like legs to exactly offset changes in surface stiffness. This study investigated human hopping on damped surfaces that dissipated up to 72% of the hopper's mechanical energy. On these surfaces, the legs did not act like pure springs. Leg muscles performed up to 24-fold more net work to replace the energy lost by the damped surface. However, considering the leg and surface together, the combination appeared to behave like a constant stiffness spring on all damped surfaces. By conserving the mechanics of the leg-surface combination regardless of surface damping, hoppers also conserved centre-of-mass motions. Thus, the normal bouncing movements of the centre of mass in hopping are not always a direct result of spring-like leg behaviour. Conserving the trajectory of the centre of mass by maintaining spring-like mechanics of the leg-surface combination may be an important control strategy for fast-legged locomotion on variable terrain. PMID:12965003

Zeaxanthin-independent energy quenching and alternative electron sinks cause a decoupling of the relationship between the photochemical reflectance index (PRI) and photosynthesis in an evergreen conifer during spring

PubMed Central

Fréchette, Emmanuelle; Wong, Christopher Y. S.; Junker, Laura Verena; Chang, Christine Yao-Yun; Ensminger, Ingo

2015-01-01

In evergreen conifers, the winter down-regulation of photosynthesis and its recovery during spring are the result of a reorganization of the chloroplast and adjustments of energy-quenching mechanisms. These phenological changes may remain undetected by remote sensing, as conifers retain green foliage during periods of photosynthetic down-regulation. The aim was to assess if the timing of the spring recovery of photosynthesis and energy-quenching characteristics are accurately monitored by the photochemical reflectance index (PRI) in the evergreen conifer Pinus strobus. The recovery of photosynthesis was studied using chlorophyll fluorescence, leaf gas exchange, leaf spectral reflectance, and photosynthetic pigment measurements. To assess if climate change might affect the recovery of photosynthesis, seedlings were exposed to cold spring conditions or warm spring conditions with elevated temperature. An early spring decoupling of the relationship between photosynthesis and PRI in both treatments was observed. This was caused by differences between the timing of the recovery of photosynthesis and the timing of carotenoid and chlorophyll pool size adjustments which are the main factors controlling PRI during spring. It was also demonstrated that zeaxanthin-independent NPQ mechanisms undetected by PRI further contributed to the early spring decoupling of the PRI–LUE relationship. An important mechanism undetected by PRI seems to involve increased electron transport around photosystem I, which was a significant energy sink during the entire spring transition, particularly in needles exposed to a combination of high light and cold temperatures. PMID:26386258

A Study of Wall Jets and Tangentially Blown Wings

DTIC Science & Technology

1981-07-01

Blowing coefficient C Chapman’constant CFF Far field constant CL Lift coefficient SCp Pressure coefficient D Reduced exit height E Normalized stagnation...that the wave interactiop zone there is (6(4/ 3 ). 74 C3471A/jos Oil % Rockwell International Science Cenier SC5055.21FR TABLE 4 - PARAMETRIC SUIMMY OF...34Analysis of Embedded Shock Waves Calculated by Relaxation Methods," Proc. Computational Fluid Dynamics Conference, Palm Springs, Calif., July 19-20, 1973, pp

Regulation of step frequency in transtibial amputee endurance athletes using a running-specific prosthesis.

PubMed

Oudenhoven, Laura M; Boes, Judith M; Hak, Laura; Faber, Gert S; Houdijk, Han

2017-01-25

Running specific prostheses (RSP) are designed to replicate the spring-like behaviour of the human leg during running, by incorporating a real physical spring in the prosthesis. Leg stiffness is an important parameter in running as it is strongly related to step frequency and running economy. To be able to select a prosthesis that contributes to the required leg stiffness of the athlete, it needs to be known to what extent the behaviour of the prosthetic leg during running is dominated by the stiffness of the prosthesis or whether it can be regulated by adaptations of the residual joints. The aim of this study was to investigate whether and how athletes with an RSP could regulate leg stiffness during distance running at different step frequencies. Seven endurance runners with an unilateral transtibial amputation performed five running trials on a treadmill at a fixed speed, while different step frequencies were imposed (preferred step frequency (PSF) and -15%, -7.5%, +7.5% and +15% of PSF). Among others, step time, ground contact time, flight time, leg stiffness and joint kinetics were measured for both legs. In the intact leg, increasing step frequency was accompanied by a decrease in both contact and flight time, while in the prosthetic leg contact time remained constant and only flight time decreased. In accordance, leg stiffness increased in the intact leg, but not in the prosthetic leg. Although a substantial contribution of the residual leg to total leg stiffness was observed, this contribution did not change considerably with changing step frequency. Amputee athletes do not seem to be able to alter prosthetic leg stiffness to regulate step frequency during running. This invariant behaviour indicates that RSP stiffness has a large effect on total leg stiffness and therefore can have an important influence on running performance. Nevertheless, since prosthetic leg stiffness was considerably lower than stiffness of the RSP, compliance of the residual leg should not be ignored when selecting RSP stiffness. Copyright © 2016 Elsevier Ltd. All rights reserved.

INTERNAL CUTTING DEVICE

DOEpatents

Russell, W.H. Jr.

1959-06-30

A device is described for removing material from the interior of a hollow workpiece so as to form a true spherical internal surface in a workpiece, or to cut radial slots of an adjustable constant depth in an already established spherical internal surface. This is accomplished by a spring loaded cutting tool adapted to move axially wherein the entire force urging the tool against the workpiece is derived from the spring. Further features of importance involve the provision of a seal between the workpiece and the cutting device and a suction device for carrying away particles of removed material.

Flow and habitat effects on juvenile fish abundance in natural and altered flow regimes

USGS Publications Warehouse

Freeman, Mary C.; Bowen, Z.H.; Bovee, K.D.; Irwin, E.R.

2001-01-01

Conserving biological resources native to large river systems increasingly depends on how flow-regulated segments of these rivers are managed. Improving management will require a better understanding of linkages between river biota and temporal variability of flow and instream habitat. However, few studies have quantified responses of native fish populations to multiyear (>2 yr) patterns of hydrologic or habitat variability in flow-regulated systems. To provide these data, we quantified young-of-year (YOY) fish abundance during four years in relation to hydrologic and habitat variability in two segments of the Tallapoosa River in the southeastern United States. One segment had an unregulated flow regime, whereas the other was flow-regulated by a peak-load generating hydropower dam. We sampled fishes annually and explored how continuously recorded flow data and physical habitat simulation models (PHABSIM) for spring (April-June) and summer (July-August) preceding each sample explained fish abundances. Patterns of YOY abundance in relation to habitat availability (median area) and habitat persistence (longest period with habitat area continuously above the long-term median area) differed between unregulated and flow-regulated sites. At the unregulated site, YOY abundances were most frequently correlated with availability of shallow-slow habitat in summer (10 species) and persistence of shallow-slow and shallow-fast habitat in spring (nine species). Additionally, abundances were negatively correlated with 1-h maximum flow in summer (five species). At the flow-regulated site, YOY abundances were more frequently correlated with persistence of shallow-water habitats (four species in spring; six species in summer) than with habitat availability or magnitude of flow extremes. The associations of YOY with habitat persistence at the flow-regulated site corresponded to the effects of flow regulation on habitat patterns. Flow regulation reduced median flows during spring and summer, which resulted in median availability of shallow-water habitats comparable to the unregulated site. However, habitat persistence was severely reduced by flow fluctuations resulting from pulsed water releases for peak-load power generation. Habitat persistence, comparable to levels in the unregulated site, only occurred during summer when low rainfall or other factors occasionally curtailed power generation. As a consequence, summer-spawning species numerically dominated the fish assemblage at the flow-regulated site; five of six spring-spawning species occurring at both study sites were significantly less abundant at the flow-regulated site. Persistence of native fishes in flow-regulated systems depends, in part, on the seasonal occurrence of stable habitat conditions that facilitate reproduction and YOY survival.

Modeling and Performance Improvement of the Constant Power Regulator Systems in Variable Displacement Axial Piston Pump

PubMed Central

Park, Sung Hwan; Lee, Ji Min; Kim, Jong Shik

2013-01-01

An irregular performance of a mechanical-type constant power regulator is considered. In order to find the cause of an irregular discharge flow at the cut-off pressure area, modeling and numerical simulations are performed to observe dynamic behavior of internal parts of the constant power regulator system for a swashplate-type axial piston pump. The commercial numerical simulation software AMESim is applied to model the mechanical-type regulator with hydraulic pump and simulate the performance of it. The validity of the simulation model of the constant power regulator system is verified by comparing simulation results with experiments. In order to find the cause of the irregular performance of the mechanical-type constant power regulator system, the behavior of main components such as the spool, sleeve, and counterbalance piston is investigated using computer simulation. The shape modification of the counterbalance piston is proposed to improve the undesirable performance of the mechanical-type constant power regulator. The performance improvement is verified by computer simulation using AMESim software. PMID:24282389

Endoscopic add-on stiffness probe for real-time soft surface characterisation in MIS.

PubMed

Faragasso, A; Stilli, A; Bimbo, J; Noh, Y; Liu, H; Nanayakkara, T; Dasgupta, P; Wurdemann, H A; Althoefer, K

2014-01-01

This paper explores a novel stiffness sensor which is mounted on the tip of a laparoscopic camera. The proposed device is able to compute stiffness when interacting with soft surfaces. The sensor can be used in Minimally Invasive Surgery, for instance, to localise tumor tissue which commonly has a higher stiffness when compared to healthy tissue. The purely mechanical sensor structure utilizes the functionality of an endoscopic camera to the maximum by visually analyzing the behavior of trackers within the field of view. Two pairs of spheres (used as easily identifiable features in the camera images) are connected to two springs with known but different spring constants. Four individual indenters attached to the spheres are used to palpate the surface. During palpation, the spheres move linearly towards the objective lens (i.e. the distance between lens and spheres is changing) resulting in variations of their diameters in the camera images. Relating the measured diameters to the different spring constants, a developed mathematical model is able to determine the surface stiffness in real-time. Tests were performed using a surgical endoscope to palpate silicon phantoms presenting different stiffness. Results show that the accuracy of the sensing system developed increases with the softness of the examined tissue.

Effective medium model for a granular monolayer on an elastic substrate

NASA Astrophysics Data System (ADS)

Maznev, Alexei

Effective medium models have been shown to work well in describing experimental observations of the interaction of surface Rayleigh waves with contact vibrations of a monolayer of microspheres . However, these models contain intrinsic conceptual problems: for example, the local displacement of the substrate at the contact point is equated to the effective medium average value of the surface displacement. I will present a rigorous derivation of the effective medium model for a random arrangement of mass-spring oscillators on an elastic half-space using elastodynamic surface Green's function formalism. We will see that the model equating the local surface displacement to the effective medium displacement is indeed valid if the spring constant of the oscillators is modified to include the stiffness of the contact calculated in the quasistatic approximation. In the case of contact vibrations of microspheres, this means using the spring constant calculated using the Hertzian contact model. Thus the results obtained in the prior work were correct despite the apparent inconsistencies in the model. The presented analysis will provide a solid foundation for effective medium models used to describe dynamics of microparticle arrays adhered to a solid substrate. This work was supported by the U. S. Army Research Office through the Institute for Soldier Nanotechnologies under Grant W911NF-13-D-0001.

Spatially resolved quantitative mapping of thermomechanical properties and phase transition temperatures using scanning probe microscopy

DOEpatents

Jesse, Stephen; Kalinin, Sergei V; Nikiforov, Maxim P

2013-07-09

An approach for the thermomechanical characterization of phase transitions in polymeric materials (polyethyleneterephthalate) by band excitation acoustic force microscopy is developed. This methodology allows the independent measurement of resonance frequency, Q factor, and oscillation amplitude of a tip-surface contact area as a function of tip temperature, from which the thermal evolution of tip-surface spring constant and mechanical dissipation can be extracted. A heating protocol maintained a constant tip-surface contact area and constant contact force, thereby allowing for reproducible measurements and quantitative extraction of material properties including temperature dependence of indentation-based elastic and loss moduli.

A new analysis of the unwinding ribbon as a delayed arming device

NASA Astrophysics Data System (ADS)

Dunn, W. P.

1982-06-01

The objective of this work was to formulate theoretical methods to enable engineers to design unwinding ribbons for use as delay arming mechanisms with reasonable accuracy and a minimum development effort. The unwinding ribbon considered here is a "wrapped' spring, which is a spiral spring made from flat metal stock closely wound. In the unstressed condition all the coils of the spring are touching. The results of the analysis are given and compared with the experimental results obtained by T. B. Alfriend. This is a more complete study than that of Alfriend since no assumptions are made concerning the moment of inertia of the coil and hub or the tension force in the ribbon bridge. Hence, two empirical constants in Alfriend's analysis were dropped in favor of exact expressions.

Zeaxanthin-independent energy quenching and alternative electron sinks cause a decoupling of the relationship between the photochemical reflectance index (PRI) and photosynthesis in an evergreen conifer during spring.

PubMed

Fréchette, Emmanuelle; Wong, Christopher Y S; Junker, Laura Verena; Chang, Christine Yao-Yun; Ensminger, Ingo

2015-12-01

In evergreen conifers, the winter down-regulation of photosynthesis and its recovery during spring are the result of a reorganization of the chloroplast and adjustments of energy-quenching mechanisms. These phenological changes may remain undetected by remote sensing, as conifers retain green foliage during periods of photosynthetic down-regulation. The aim was to assess if the timing of the spring recovery of photosynthesis and energy-quenching characteristics are accurately monitored by the photochemical reflectance index (PRI) in the evergreen conifer Pinus strobus. The recovery of photosynthesis was studied using chlorophyll fluorescence, leaf gas exchange, leaf spectral reflectance, and photosynthetic pigment measurements. To assess if climate change might affect the recovery of photosynthesis, seedlings were exposed to cold spring conditions or warm spring conditions with elevated temperature. An early spring decoupling of the relationship between photosynthesis and PRI in both treatments was observed. This was caused by differences between the timing of the recovery of photosynthesis and the timing of carotenoid and chlorophyll pool size adjustments which are the main factors controlling PRI during spring. It was also demonstrated that zeaxanthin-independent NPQ mechanisms undetected by PRI further contributed to the early spring decoupling of the PRI-LUE relationship. An important mechanism undetected by PRI seems to involve increased electron transport around photosystem I, which was a significant energy sink during the entire spring transition, particularly in needles exposed to a combination of high light and cold temperatures. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Estimation of uptake rate constants for PCB congeners accumulated by semipermeable membrane devices and brown treat (Salmo trutta)

USGS Publications Warehouse

Meadows, J.C.; Echols, K.R.; Huckins, J.N.; Borsuk, F.A.; Carline, R.F.; Tillitt, D.E.

1998-01-01

The triolein-filled semipermeable membrane device (SPMD) is a simple and effective method of assessing the presence of waterborne hydrophobic chemicals. Uptake rate constants for individual chemicals are needed to accurately relate the amounts of chemicals accumulated by the SPMD to dissolved water concentrations. Brown trout and SPMDs were exposed to PCB- contaminated groundwater in a spring for 28 days to calculate and compare uptake rates of specific PCB congeners by the two matrixes. Total PCB congener concentrations in water samples from the spring were assessed and corrected for estimated total organic carbon (TOC) sorption to estimate total dissolved concentrations. Whole and dissolved concentrations averaged 4.9 and 3.7 ??g/L, respectively, during the exposure. Total concentrations of PCBs in fish rose from 0.06 to 118.3 ??g/g during the 28-day exposure, while concentrations in the SPMD rose from 0.03 to 203.4 ??g/ g. Uptake rate constants (k1) estimated for SPMDs and brown trout were very similar, with k1 values for SPMDs ranging from one to two times those of the fish. The pattern of congener uptake by the fish and SPMDs was also similar. The rates of uptake generally increased or decreased with increasing K(ow), depending on the assumption of presence or absence of TOC.The triolein-filled semipermeable membrane device (SPMD) is a simple and effective method of assessing the presence of waterborne hydrophobic chemicals. Uptake rate constants for individual chemicals are needed to accurately relate the amounts of chemicals accumulated by the SPMB to dissolved water concentrations. Brown trout and SPMDs were exposed to PCB-contaminated groundwater in a spring for 28 days to calculate and compare uptake rates of specific PCB congeners by the two matrixes. Total PCB congener concentrations in water samples from the spring were assessed and corrected for estimated total organic carbon (TOC) sorption to estimate total dissolved concentrations. Whole and dissolved concentrations averaged 4.9 and 3.7 ??g/L, respectively, during the exposure. Total concentrations of PCBs in fish rose from 0.06 to 118.3 ??g/g during the 28-day exposure, while concentrations in the SPMD rose from 0.03 to 203.4 ??g/g. Uptake rate constants (k1) estimated for SPMDs and brown trout were very similar, with k1 values for SPMDs ranging from one to two times those of the fish. The pattern of congener uptake by the fish and SPMBs was also similar. The rates of uptake generally increased or decreased with increasing KOW, depending on the assumption of presence or absence of TOC.

High-intensity sprint fatigue does not alter constant-submaximal velocity running mechanics and spring-mass behavior.

PubMed

Morin, Jean-Benoit; Tomazin, Katja; Samozino, Pierre; Edouard, Pascal; Millet, Guillaume Y

2012-04-01

We investigated the changes in constant velocity spring-mass behavior after high intensity sprint fatigue in order to better interpret the results recently reported after ultra-long distance (ULD) exercises. Our hypothesis was that after repeated sprints (RS), subjects may likely experience losses of force such as after ULD, but the necessity to modify their running pattern to attenuate the overall impact at each step (such as after ULD) may not be present. Eleven male subjects performed four sets of five 6-s sprints with 24-s recovery between sprints and 3 min between sets, on a sprint treadmill and on a bicycle ergometer. For each session, their running mechanics and spring-mass characteristics were measured at 10 and 20 km h(-1) on an instrumented treadmill before and after RS. Two-way (period and velocity) ANOVAs showed that high-intensity fatigue did not induce any change in the constant velocity running pattern at low or high velocity, after both running and cycling RS, despite significant decreases (P < 0.001) in maximal power (-27.1 ± 8.2% after running RS and -15.4 ± 11.5 % after cycling RS) and knee extensors maximal voluntary force (-18.8 ± 6.7 % after running RS and -15.0 ± 7.6 % after cycling RS). These results bring indirect support to the hypothesis put forward in recent ULD studies that the changes in running mechanics observed after ULD are likely not related to the decrease in strength capabilities, but rather to the necessity for subjects to adopt a protective running pattern.

Genetic and Molecular Analysis of the Mechanisms by which TSC Regulates Neuronal Differentiation

DTIC Science & Technology

2009-03-01

2004 Programmed autophagy in the Drosophila fat body is in- duced by ecdysone through regulation of the PI3K pathway. Dev. Cell 7: 179–192. Sarbassov...embryonic Drosophila CNS. Mech. Dev. 64: 137–151. Scott, R. C., O. Schuldiner and T. P. Neufeld, 2004 Role and reg- ulation of starvation-induced autophagy ...in The Development of Drosophila melanogaster , edited by M. Bates and A. Martinez-Arias. Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY

Modeling and Evaluation of Canted Coil Springs as High Temperature Seal Preloading Devices

NASA Technical Reports Server (NTRS)

Oswald, Jay J.; Mullen, Robert L.; Dunlap, Patrick H., Jr.; Steinetz, Bruce M.

2004-01-01

Future reusable launch vehicles will require advanced structural seals. This includes propulsion seals along edges and hinge lines in hypersonic engines, and control surface seals for movable flaps and elevons on proposed reentry vehicles. Seals must remain in sealing engagement with opposing surfaces, for multiple missions, even though the seal gap may be opening and closing due to thermal and structural loads. To meet this requirement either the seals themselves must be resilient or there must be a resilient structural element behind the seals. Case Western Reserve University is working with NASA s Glenn Research Center to develop more resilient high temperature seal components and preloading devices. Results are presented for a finite element analysis of a canted coil spring that is being considered as a high temperature seal preloading device. This type of spring is a leading candidate due to its ability to provide nearly constant force over a large deflection. The finite element analyses were verified by comparing them to experimental results of canted coil springs of three different stiffnesses, measured at Glenn Research Center. Once validated the parameterized model was combined with a scripting algorithm to assess the effects of key spring design variables (wire diameter, coils per inch, cant amplitude, eccentricity, and spring width) on spring stiffness and maximum Von Mises stress to aid in subsequent design.

HATCH CONNECTING TEMPERED AIR CHAMBER AND HOT AIR CHAMBER OF ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

HATCH CONNECTING TEMPERED AIR CHAMBER AND HOT AIR CHAMBER OF PLENUM WITH ATTACHED DRAFT REGULATOR. - Hot Springs National Park, Bathhouse Row, Superior Bathhouse: Mechanical & Piping Systems, State Highway 7, 1 mile north of U.S. Highway 70, Hot Springs, Garland County, AR

Detection of short-term changes in vegetation cover by use of LANDSAT imagery. [Arizona

NASA Technical Reports Server (NTRS)

Turner, R. M. (Principal Investigator); Wiseman, F. M.

1975-01-01

The author has identified the following significant results. By using a constant band 6 to band 5 radiance ratio of 1.25, the changing pattern of areas of relatively dense vegetation cover was detected for the semiarid region in the vicinity of Tucson, Arizona. Electronically produced binary thematic masks were used to map areas with dense vegetation. The foliar cover threshold represented by the ratio was not accurately determined but field measurements show that the threshold lies in the range of 10 to 25 percent foliage cover. Montana evergreen forests with constant dense cover were correctly shown to exceed the threshold on all dates. The summer active grassland exceeded the threshold in the summer unless rainfall was insufficient. Desert areas exceeded the threshold during the spring of 1973 following heavy rains; the same areas during the rainless spring of 1974 did not exceed threshold. Irrigated fields, parks, golf courses, and riparian communities were among the habitats most frequently surpassing the threshold.

The Dependency in the Elasticity of the Saccharomyces cerevisiae Cell Wall upon Cell Viability and Membrane Integrity

NASA Astrophysics Data System (ADS)

McPherson, Dacia; Zhu, Chenhui; Yi, Youngwoo; Clark, Noel

2007-03-01

In this study the elastic spring constant of the yeast cell wall is probed with the atomic force microscope (AFM) under variable conditions. Cells were sequentially analyzed in rich growth medium (YPD), a 0.8 M NaCl rich growth medium solution and an injection of 0.01% sodium azide solution. Cells in late log phase, which have variable diameters within three to five microns, were immobilized on a patterned silicon substrate with holes approximately 3.8um in diameter and 1.5um deep that was functionalized with polyethylenimine prior to cell application. Force curves were taken moving laterally across the cell in one dimension after exposure to each medium. Spring constants of the cells, calculated from force curves, displayed a positional dependency and marked differences in high osmolarity medium and after the injection of sodium azide. This study demonstrates the ability of the AFM to investigate changes in cell morphology and correlate those findings to underlying physiological processes.

An experimental study of the effect of mooring systems on the dynamics of a SPAR buoy-type floating offshore wind turbine

NASA Astrophysics Data System (ADS)

Hong, Sinpyo; Lee, Inwon; Park, Seong Hyeon; Lee, Cheolmin; Chun, Ho-Hwan; Lim, Hee Chang

2015-09-01

An experimental study of the effect of mooring systems on the dynamics of a SPAR buoy-type floating offshore wind turbine is presented. The effects of the Center of Gravity (COG), mooring line spring constant, and fair-lead location on the turbine's motion in response to regular waves are investigated. Experimental results show that for a typical mooring system of a SPAR buoy-type Floating Offshore Wind Turbine (FOWT), the effect of mooring systems on the dynamics of the turbine can be considered negligible. However, the pitch decreases notably as the COG increases. The COG and spring constant of the mooring line have a negligible effect on the fairlead displacement. Numerical simulation and sensitivity analysis show that the wind turbine motion and its sensitivity to changes in the mooring system and COG are very large near resonant frequencies. The test results can be used to validate numerical simulation tools for FOWTs.

Periodic spring-mass running over uneven terrain through feedforward control of landing conditions.

PubMed

Palmer, Luther R; Eaton, Caitrin E

2014-09-01

This work pursues a feedforward control algorithm for high-speed legged locomotion over uneven terrain. Being able to rapidly negotiate uneven terrain without visual or a priori information about the terrain will allow legged systems to be used in time-critical applications and alongside fast-moving humans or vehicles. The algorithm is shown here implemented on a spring-loaded inverted pendulum model in simulation, and can be configured to approach fixed running height over uneven terrain or self-stable terrain following. Offline search identifies unique landing conditions that achieve a desired apex height with a constant stride period over varying ground levels. Because the time between the apex and touchdown events is directly related to ground height, the landing conditions can be computed in real time as continuous functions of this falling time. Enforcing a constant stride period reduces the need for inertial sensing of the apex event, which is nontrivial for physical systems, and allows for clocked feedfoward control of the swing leg.

Non-collinear valve actuator

NASA Technical Reports Server (NTRS)

Richard, James A. (Inventor)

2012-01-01

A non-collinear valve actuator includes a primary actuating system and a return spring system with each applying forces to a linkage system in order to regulate the flow of a quarter-turn valve. The primary actuating system and return spring system are positioned non-collinearly, which simply means the primary actuating system and return spring system are not in line with each other. By positioning the primary actuating system and return spring system in this manner, the primary actuating system can undergo a larger stroke while the return spring system experiences significantly less displacement. This allows the length of the return spring to be reduced due to the minimization of displacement thereby reducing the weight of the return spring system. By allowing the primary actuating system to undergo longer strokes, the weight of the primary actuating system may also be reduced. Accordingly, the weight of the non-collinear valve actuator is reduced.

Antarctic Phytoplankton down-regulate Their Carbon-Concentrating Mechanisms under High CO2 with no Change in Growth Rates

NASA Astrophysics Data System (ADS)

Kranz, S. A.; Young, J. N.; Goldman, J.; Tortell, P. D.; Morel, F. M.

2016-02-01

High-latitude oceans, in particular the coastal Western Antarctic Peninsula (WAP) region of the Southern Ocean, are experiencing a rapidly changing environment due to rising surface ocean temperatures and CO2 concentrations. However, the direct effect of increasing CO2 on polar ocean primary production is unclear, with a number of experiments showing conflicting results. It has been hypothesized that increased CO2 may cause a reduction of the energy-intensive carbon concentrating mechanism (CCM) in phytoplankton, and these energy savings may lead to increased productivity. To test this hypothesis, we incubated natural phytoplankton communities in the WAP under high (800 ppm), current (400 ppm) and low (100 ppm) CO2 for 2 to 3 wk during the austral spring-summer of 2012/2013. In 2 incubations with diatom-dominated phytoplankton assemblages, high CO2 led to a clear down-regulation of CCM activity, as evidenced by an increase in half-saturation constants for CO2, a decrease in external carbonic anhydrase activity and a higher biological fractionation of stable carbon isotopes. In a third incubation, there was no observable regulation of the CCM. We did not observe a significant effect of CO2 on growth rates or community composition in the diatom-dominated communities. The lack of a measureable effect on growth despite CCM down-regulation is likely explained by a very small energetic requirement to concentrate CO2 and saturate Rubisco at low temperatures.

Feasibility and scalability of spring parameters in distraction enterogenesis in a murine model.

PubMed

Huynh, Nhan; Dubrovsky, Genia; Rouch, Joshua D; Scott, Andrew; Stelzner, Matthias; Shekherdimian, Shant; Dunn, James C Y

2017-07-01

Distraction enterogenesis has been investigated as a novel treatment for short bowel syndrome (SBS). With variable intestinal sizes, it is critical to determine safe, translatable spring characteristics in differently sized animal models before clinical use. Nitinol springs have been shown to lengthen intestines in rats and pigs. Here, we show spring-mediated intestinal lengthening is scalable and feasible in a murine model. A 10-mm nitinol spring was compressed to 3 mm and placed in a 5-mm intestinal segment isolated from continuity in mice. A noncompressed spring placed in a similar fashion served as a control. Spring parameters were proportionally extrapolated from previous spring parameters to accommodate the smaller size of murine intestines. After 2-3 wk, the intestinal segments were examined for size and histology. Experimental group with spring constants, k = 0.2-1.4 N/m, showed intestinal lengthening from 5.0 ± 0.6 mm to 9.5 ± 0.8 mm (P < 0.0001), whereas control segments lengthened from 5.3 ± 0.5 mm to 6.4 ± 1.0 mm (P < 0.02). Diameter increased similarly in both groups. Isolated segment perforation was noted when k ≥ 0.8 N/m. Histologically, lengthened segments had increased muscularis thickness and crypt depth in comparison to normal intestine. Nitinol springs with k ≤ 0.4 N/m can safely yield nearly 2-fold distraction enterogenesis in length and diameter in a scalable mouse model. Not only does this study derive the safe ranges and translatable spring characteristics in a scalable murine model for patients with short bowel syndrome, it also demonstrates the feasibility of spring-mediated intestinal lengthening in a mouse, which can be used to study underlying mechanisms in the future. Copyright © 2017 Elsevier Inc. All rights reserved.

A novel constant-force scanning probe incorporating mechanical-magnetic coupled structures.

PubMed

Wang, Hongxi; Zhao, Jian; Gao, Renjing; Yang, Yintang

2011-07-01

A one-dimensional scanning probe with constant measuring force is designed and fabricated by utilizing the negative stiffness of the magnetic coupled structure, which mainly consists of the magnetic structure, the parallel guidance mechanism, and the pre-stressed spring. Based on the theory of material mechanics and the equivalent surface current model for computing the magnetic force, the analytical model of the scanning probe subjected to multi-forces is established, and the nonlinear relationship between the measuring force and the probe displacement is obtained. The practicability of introducing magnetic coupled structure in the constant-force probe is validated by the consistency of the results in numerical simulation and experiments.

Rapid estimation of glucosinolate thermal degradation rate constants in leaves of Chinese kale and broccoli (Brassica oleracea) in two seasons.

PubMed

Hennig, Kristin; Verkerk, Ruud; Bonnema, Guusje; Dekker, Matthijs

2012-08-15

Kinetic modeling was used as a tool to quantitatively estimate glucosinolate thermal degradation rate constants. Literature shows that thermal degradation rates differ in different vegetables. Well-characterized plant material, leaves of broccoli and Chinese kale plants grown in two seasons, was used in the study. It was shown that a first-order reaction is appropriate to model glucosinolate degradation independent from the season. No difference in degradation rate constants of structurally identical glucosinolates was found between broccoli and Chinese kale leaves when grown in the same season. However, glucosinolate degradation rate constants were highly affected by the season (20-80% increase in spring compared to autumn). These results suggest that differences in glucosinolate degradation rate constants can be due to variation in environmental as well as genetic factors. Furthermore, a methodology to estimate rate constants rapidly is provided to enable the analysis of high sample numbers for future studies.

Groundwater, surface-water, and water-chemistry data, Black Mesa area, northeastern Arizona—2013–2015

USGS Publications Warehouse

Macy, Jamie P.; Mason, Jon P.

2017-12-07

The Navajo (N) aquifer is an extensive aquifer and the primary source of groundwater in the 5,400-square-mile Black Mesa area in northeastern Arizona. Availability of water is an important issue in northeastern Arizona because of continued water requirements for industrial and municipal use by a growing population and because of low precipitation in the arid climate of the Black Mesa area. Precipitation in the area typically is between 6 and 16 inches per year.The U.S. Geological Survey water-monitoring program in the Black Mesa area began in 1971 and provides information about the long-term effects of groundwater withdrawals from the N aquifer for industrial and municipal uses. This report presents results of data collected as part of the monitoring program in the Black Mesa area from January 2013 to December 2015. The monitoring program includes measurements of (1) groundwater withdrawals (pumping), (2) groundwater levels, (3) spring discharge, (4) surface-water discharge, and (5) groundwater chemistry.In 2013, total groundwater withdrawals were 3,980 acre-feet (ft), in 2014 total withdrawals were 4,170 acre-ft, and in 2015 total withdrawals were 3,970 acre-ft. From 2013 to 2015 total withdrawals varied by less than 5 percent.From 2014 to 2015, annually measured water levels in the Black Mesa area declined in 9 of 15 wells that were available for comparison in the unconfined areas of the N aquifer, and the median change was -0.1 feet. Water levels declined in 3 of 16 wells measured in the confined area of the aquifer. The median change for the confined area of the aquifer was 0.6 feet. From the prestress period (prior to 1965) to 2015, the median water-level change for 34 wells in both the confined and unconfined areas was -13.2 feet; the median water-level changes were -1.7 feet for 16 wells measured in the unconfined areas and -42.3 feet for 18 wells measured in the confined area.Spring flow was measured at four springs in 2014. Flow fluctuated during the period of record for Burro Spring and Unnamed Spring near Dennehotso, but a decreasing trend was statistically significant (p<0.05) at Moenkopi School Spring and Pasture Canyon Spring. Discharge at Burro Spring has remained relatively constant since it was first measured in the 1980s and discharge at Unnamed Spring near Dennehotso has fluctuated for the period of record. Trend analysis for discharge at Moenkopi and Pasture Canyon Springs yielded a slope significantly different (p<0.05) from zero.Continuous records of surface-water discharge in the Black Mesa area were collected from streamflow-gaging stations at the following sites: Moenkopi Wash at Moenkopi 09401260 (1976 to 2015), Dinnebito Wash near Sand Springs 09401110 (1993 to 2015), Polacca Wash near Second Mesa 09400568 (1994 to 2015), and Pasture Canyon Springs 09401265 (2004 to 2015). Median winter flows (November through February) of each water year were used as an index of the amount of groundwater discharge at the above-named sites. For the period of record of each streamflow-gaging station, the median winter flows have generally remained constant, which suggests no change in groundwater discharge.In 2014, water samples collected from four springs in the Black Mesa area were analyzed for selected chemical constituents, and the results were compared with previous analyses. Dissolved solids, chloride, and sulfate concentrations increased at Moenkopi School Spring during the more than 25 years of record at that site. Concentrations of dissolved solids, chloride, and sulfate at Pasture Canyon Spring have not varied significantly (p>0.05) since the early 1980s, and there is no increasing or decreasing trend in those data. Concentrations of dissolved solids, chloride, and sulfate at Burro Spring and Unnamed Spring near Dennehotso have varied for the period of record, but there is no increasing or decreasing statistical trend in the data.

75 FR 21749 - Spring 2010 Semiannual Agenda of Regulations

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-26

...In compliance with Executive Order 12866, entitled ``Regulatory Planning and Review,'' and the Regulatory Flexibility Act, as amended, the Department of Commerce (Department), in the spring and fall of each year, publishes in the Federal Register an agenda of regulations under development of review over the next 12 months. Rulemaking actions are grouped according to prerulemaking, proposed rules, final rules, long-term actions, and rulemaking actions completed since the fall 2009 agenda. The purpose of the agenda is to provide information to the public on regulations currently under review, being proposed, or issued by the Department. The agenda is intended to facilitate comments and views by interested members of the public.

Effects of Chemistry and Processing on the Fracture Related Properties of P/M Alloy CT91.

DTIC Science & Technology

1985-08-01

Paris- Erdogan equation [151]. da/dN = AAk’ (8) where A and m are material constants. Stage II is generally characterized by a continuum mechanism...1. Paris and Erdogan [151] da/dN = CAKm (15) where da/dN = crack growth per cycle C, m = material constants AK = stress intensity parameter range The...extensometer was placed on two strips of masking tape to avoid notching the specimen and was carefully attached by two springs. A plastic bag was placed

Analysis of flowpath dynamics in a steep unchannelled hollow in the Tanakami Mountains of Japan

NASA Astrophysics Data System (ADS)

Uchida, Taro; Asano, Yuko; Ohte, Nobuhito; Mizuyama, Takahisa

2003-02-01

Simultaneous measurements of runoff, soil pore water pressure, soil temperature, and water chemistry were taken to evaluate the spatial and temporal nature of flowpaths in a steep 0·1 ha unchannelled hollow in the Tanakami Mountains of central Japan. Tensiometers showed that a saturated area formed and a downward hydraulic gradient existed continuously in the area near a spring. The amplitude of the soil-bedrock interface temperature difference near the spring was smaller than that in the upper hollow, although soil depth near the spring was smaller than in the upper hollow. This suggests that, in the small perennially saturated area near the spring, water percolates through the vadose zone mixed with water emerging from the bedrock. During summer rainstorms, the soil-bedrock interface temperature increased as the ground became saturated. Silica and sodium concentrations in the transient saturated groundwater during these episodes were significantly lower than those in the perennial groundwater, suggesting that both rainwater and shallow soil water had important effects on the formation of transient saturated groundwater on the upper slope. In this case, the streamflow varied with the soil pore water pressure on the upper slope; the soil pore water pressure in the area near the spring remained nearly constant. Moreover, the spring water temperature was almost the same as the transient groundwater temperature on the upper slope. This indicates that the transient groundwater in the upper slope flowed to the spring via lateral preferential paths. The relative inflow of bedrock groundwater to the spring decreased as rainfall increased.

Numerical investigation on the implications of spring temperature and discharge rate with respect to the geothermal background in a fault zone

NASA Astrophysics Data System (ADS)

Jiang, Zhenjiao; Xu, Tianfu; Mariethoz, Gregoire

2018-04-01

Geothermal springs are some of the most obvious indicators of the existence of high-temperature geothermal resources in the subsurface. However, geothermal springs can also occur in areas of low average subsurface temperatures, which makes it difficult to assess exploitable zones. To address this problem, this study quantitatively analyzes the conditions associated with the formation of geothermal springs in fault zones, and numerically investigates the implications that outflow temperature and discharge rate from geothermal springs have on the geothermal background in the subsurface. It is concluded that the temperature of geothermal springs in fault zones is mainly controlled by the recharge rate from the country rock and the hydraulic conductivity in the fault damage zone. Importantly, the topography of the fault trace on the land surface plays an important role in determining the thermal temperature. In fault zones with a permeability higher than 1 mD and a lateral recharge rate from the country rock higher than 1 m3/day, convection plays a dominant role in the heat transport rather than thermal conduction. The geothermal springs do not necessarily occur in the place having an abnormal geothermal background (with the temperature at certain depth exceeding the temperature inferred by the global average continental geothermal gradient of 30 °C/km). Assuming a constant temperature (90 °C here, to represent a normal geothermal background in the subsurface at a depth of 3,000 m), the conditions required for the occurrence of geothermal springs were quantitatively determined.

Gradual Introduction of Some Aspects of Quantum Mechanics in a High School Curriculum.

ERIC Educational Resources Information Center

Cuppari, A.; Rinaudo, G.; Robutti, O.; Violino, P.

1997-01-01

Suggests that the basic concepts of quantum mechanics can be introduced at the high school level by considering the action of classical mechanics, then introducing Planck's constant as the granularity of that action. Uses the periodic motion of a spring as a practical example. (AIM)

Device induces lungs to maintain known constant pressure

NASA Technical Reports Server (NTRS)

Lippitt, M. W.; Reed, J. H.

1964-01-01

This device requires the use of thoracic muscles to maintain prescribed air pressure in the lungs for brief periods. It consists of a clear plastic hollow cylinder fitted with a mouthpiece, a spring-loaded piston, and a small vent for escaping air when exhalation into the mouthpiece displaces the piston.

Analysis of Fluctuating Friction Version in Sheet Metallic Designing

NASA Astrophysics Data System (ADS)

Ambarayil Joy, Jithin; Jung, Dong Won

2018-02-01

Conservative Coulomb method indicates steady constant of rub in thin metal panel making that appears or feels close to the real thing. It contributes to describing attainable future event too high shear pressure in making ahead in the position of high R-value steel (AHRS). The study is conducted by pretend the making and spring back of a specific panel to understand the characteristic of the stamping procedure. Corresponding of the describe probable future results with (i) physical force-dependent changeable rub method, (ii) perpetual rub method, and the conclusion of exploratory facts point out a significant upgrading of spring back forecast with the prospective method.

Seal Apparatus and Methods to Manufacture Thereof

NASA Technical Reports Server (NTRS)

Richard, James A. (Inventor)

2013-01-01

In some implementations, apparatus and methods are provided through which a dynamic cryogenic seal is manufactured. In some implementations, the seal includes a retainer and a spring-seal assembly, the assembly being comprised of a main spring housing and fluorine-containing polymer seals. In some implementations, either a radial seal, or an axial (or "piston seal") is provided. In some implementations, methods of manufacturing the dynamic cryogenic seal are also provided. In some implementations, the methods include assembling the components while either heated or cooled, taking advantage of thermal expansion and contraction, such that there is a strong interference fit between the components at room temperature. In some implementations, this process ensures that the weaker fluorine-containing polymer seal is forced to expand and contract with the stronger retainer and spring and is under constant preload. In some implementations, the fluorine-containing polymer is therefore fluidized and retained, and can not lift off.

Almost-dispersionless pulse transport in long quasiuniform spring-mass chains: A different kind of Newton's cradle

NASA Astrophysics Data System (ADS)

Vaia, Ruggero

2018-04-01

Almost-dispersionless pulse transfer between the extremal masses of a uniform harmonic spring-mass chain of arbitrary length can be induced by suitably modifying two masses and their spring's elastic constant at both extrema of the chain. It is shown that a deviation (or a pulse) imposed to the first mass gives rise to a wave packet that, after a time of the order of the chain length, almost perfectly reproduces the same deviation (pulse) at the opposite end, with an amplitude loss that is as small as 1.3% in the infinite-length limit; such a dynamics can continue back and forth again for several times before dispersion cleared the effect. The underlying coherence mechanism is that the initial condition excites a bunch of normal modes with almost equal frequency spacing. This constitutes a possible mechanism for efficient energy transfer, e.g., in nanofabricated structures.

A study on a wheel-based stair-climbing robot with a hopping mechanism

NASA Astrophysics Data System (ADS)

Kikuchi, Koki; Sakaguchi, Keisuke; Sudo, Takayuki; Bushida, Naoki; Chiba, Yasuhiro; Asai, Yuji

2008-08-01

In this study, we propose a simple hopping mechanism using the vibration of a two-degree-of-freedom system for a wheel-based stair-climbing robot. The robot, consisting of two bodies connected by springs and a wire, hops by releasing energy stored in the springs and quickly travels using wheels mounted in its lower body. The trajectories of the bodies during hopping change in accordance with the design parameters, such as the reduced mass of the two bodies, the mass ratio between the upper and lower bodies, the spring constant, the control parameters such as the initial contraction of the spring and the wire tension. This property allows the robot to quickly and economically climb up and down stairs, leap over obstacles, and landing softly without complex control. In this paper, the characteristics of hopping motion for the design and control parameters are clarified by both numerical simulations and experiments. Furthermore, using the robot design based on the results the abilities to hop up and down a step, leap over a cable, and land softly are demonstrated.

Groundwater, surface-water, and water-chemistry data, Black Mesa area, northeastern Arizona—2012–2013

USGS Publications Warehouse

Macy, Jamie P.; Truini, Margot

2016-03-02

The Navajo (N) aquifer is an extensive aquifer and the primary source of groundwater in the 5,400-square-mile Black Mesa area in northeastern Arizona. Availability of water is an important issue in northeastern Arizona because of continued water requirements for industrial and municipal use by a growing population and because of low precipitation in the arid climate of the Black Mesa area. Precipitation in the area typically is between 6 and 14 inches per year.The U.S. Geological Survey water-monitoring program in the Black Mesa area began in 1971 and provides information about the long-term effects of groundwater withdrawals from the N aquifer for industrial and municipal uses. This report presents results of data collected as part of the monitoring program in the Black Mesa area from January 2012 to September 2013. The monitoring program includes measurements of (1) groundwater withdrawals, (2) groundwater levels, (3) spring discharge, (4) surface-water discharge, and (5) groundwater chemistry.In calendar year 2012, total groundwater withdrawals were 4,010 acre-ft, industrial withdrawals were 1,370 acre-ft, and municipal withdrawals were 2,640 acre-ft. Total withdrawals during 2012 were about 45 percent less than total withdrawals in 2005 because of Peabody Western Coal Company’s discontinued use of water to transport coal in a coal slurry pipeline. From 2011 to 2012 total withdrawals decreased by 10 percent; industrial withdrawals decreased by approximately 1 percent, and total municipal withdrawals decreased by 15 percent.From 2012 to 2013, annually measured water levels in the Black Mesa area declined in 6 of 16 wells that were available for comparison in the unconfined areas of the N aquifer, and the median change was 0.8 feet. Water levels declined in 5 of 16 wells measured in the confined area of the aquifer. The median change for the confined area of the aquifer was 0.3 feet. From the prestress period (prior to 1965) to 2013, the median water-level change for 34 wells in both the confined and unconfined areas was -13.5 feet; the median water-level changes were -0.8 feet for 16 wells measured in the unconfined areas and -51.0 feet for 16 wells measured in the confined area.Spring flow was measured at four springs in 2013; Burro, Unnamed Spring near Dennehotso, Moenkopi School, and Pasture Canyon Springs. Flow fluctuated during the period of record for Burro and Unnamed Springs near Dennehotso, but a decreasing trend was apparent at Moenkopi School Spring and Pasture Canyon Spring. Discharge at Burro Spring has remained relatively constant since it was first measured in the 1980s and discharge at Unnamed Spring near Dennehotso has fluctuated for the period of record at each spring. Trend analysis for discharge at Moenkopi School and Pasture Canyon Springs showed a decreasing trend.Continuous records of surface-water discharge in the Black Mesa area were collected from streamflow-gaging stations at the following sites: Moenkopi Wash at Moenkopi 09401260 (1976 to 2013), Dinnebito Wash near Sand Springs 09401110 (1993 to 2013), Polacca Wash near Second Mesa 09400568 (1994 to 2013), and Pasture Canyon Springs 09401265 (2004 to 2013). Median winter flows (November through February) from these sites for each water year were used as an index of the amount of groundwater discharge. For the period of record of each streamflow-gaging station, the median winter flows have generally remained constant, which suggests no change in groundwater discharge.In 2013, water samples collected from 12 wells and 4 springs in the Black Mesa area were analyzed for selected chemical constituents, and the results were compared with previous analyses. Concentrations of dissolved solids, chloride, and sulfate have varied at all 12 wells for the period of record, but neither increasing nor decreasing trends over time were found. Dissolved solids, chloride, and sulfate concentrations increased at Moenkopi School Spring during the more than 13 years of record at that site. Concentrations of dissolved solids, chloride, and sulfate at Pasture Canyon Spring have not varied significantly since the early 1980s. Concentrations of dissolved solids, chloride, and sulfate at Burro Spring and Unnamed Spring near Dennehotso have varied for the period of record with no increasing or decreasing trend in the data.

Ethics or Choosing Complexity in Music Relations

ERIC Educational Resources Information Center

Schmidt, Patrick

2012-01-01

The hardship and pleasure of a life in ethics, as in music, springs not from a commitment to the veneration of stability, refinement and consistency, as some political and aesthetic discourses often suggest. Rather, the productive tensions of ethical living arise from a restless interaction between constant motion and adaptability; both marks of…

Pneumatic shutoff and time-delay valve operates at controlled rate

NASA Technical Reports Server (NTRS)

Horning, J. L.; Tomlinson, L. E.

1966-01-01

Shutoff and time delay valve, which incorporates a metering spool that moves at constant velocity under pneumatic pressure and spring compression, increases fluid-flow area at a uniform rate. Diaphragm areas, control cavity volume, and bleed-orifice size may be varied to give any desired combination of time delay and spool travel time.

Not Dressing the Part, and Other Interview Mistakes

ERIC Educational Resources Information Center

Barden, Dennis M.

2013-01-01

Spring is interview season for aspiring presidents, provosts, and deans. It's when search consultants spend a lot of time sitting in meeting rooms at airport hotels watching candidates engage with hiring committees in the ritual dance of the preliminary interview. Even after 15 years of that, the author is constantly surprised by the approaches…

Relationship between neighbor number and vibrational spectra in disordered colloidal clusters with attractive interactions

NASA Astrophysics Data System (ADS)

Yunker, Peter J.; Zhang, Zexin; Gratale, Matthew; Chen, Ke; Yodh, A. G.

2013-03-01

We study connections between vibrational spectra and average nearest neighbor number in disordered clusters of colloidal particles with attractive interactions. Measurements of displacement covariances between particles in each cluster permit calculation of the stiffness matrix, which contains effective spring constants linking pairs of particles. From the cluster stiffness matrix, we derive vibrational properties of corresponding "shadow" glassy clusters, with the same geometric configuration and interactions as the "source" cluster but without damping. Here, we investigate the stiffness matrix to elucidate the origin of the correlations between the median frequency of cluster vibrational modes and average number of nearest neighbors in the cluster. We find that the mean confining stiffness of particles in a cluster, i.e., the ensemble-averaged sum of nearest neighbor spring constants, correlates strongly with average nearest neighbor number, and even more strongly with median frequency. Further, we find that the average oscillation frequency of an individual particle is set by the total stiffness of its nearest neighbor bonds; this average frequency increases as the square root of the nearest neighbor bond stiffness, in a manner similar to the simple harmonic oscillator.

Clausius inequality beyond the weak-coupling limit: the quantum Brownian oscillator.

PubMed

Kim, Ilki; Mahler, Günter

2010-01-01

We consider a quantum linear oscillator coupled at an arbitrary strength to a bath at an arbitrary temperature. We find an exact closed expression for the oscillator density operator. This state is noncanonical but can be shown to be equivalent to that of an uncoupled linear oscillator at an effective temperature T*(eff) with an effective mass and an effective spring constant. We derive an effective Clausius inequality deltaQ*(eff)< or =T*(eff)dS , where deltaQ*(eff) is the heat exchanged between the effective (weakly coupled) oscillator and the bath, and S represents a thermal entropy of the effective oscillator, being identical to the von-Neumann entropy of the coupled oscillator. Using this inequality (for a cyclic process in terms of a variation of the coupling strength) we confirm the validity of the second law. For a fixed coupling strength this inequality can also be tested for a process in terms of a variation of either the oscillator mass or its spring constant. Then it is never violated. The properly defined Clausius inequality is thus more robust than assumed previously.

High Speed Video Measurements of a Magneto-optical Trap

NASA Astrophysics Data System (ADS)

Horstman, Luke; Graber, Curtis; Erickson, Seth; Slattery, Anna; Hoyt, Chad

2016-05-01

We present a video method to observe the mechanical properties of a lithium magneto-optical trap. A sinusoidally amplitude-modulated laser beam perturbed a collection of trapped ce7 Li atoms and the oscillatory response was recorded with a NAC Memrecam GX-8 high speed camera at 10,000 frames per second. We characterized the trap by modeling the oscillating cold atoms as a damped, driven, harmonic oscillator. Matlab scripts tracked the atomic cloud movement and relative phase directly from the captured high speed video frames. The trap spring constant, with magnetic field gradient bz = 36 G/cm, was measured to be 4 . 5 +/- . 5 ×10-19 N/m, which implies a trap resonant frequency of 988 +/- 55 Hz. Additionally, at bz = 27 G/cm the spring constant was measured to be 2 . 3 +/- . 2 ×10-19 N/m, which corresponds to a resonant frequency of 707 +/- 30 Hz. These properties at bz = 18 G/cm were found to be 8 . 8 +/- . 5 ×10-20 N/m, and 438 +/- 13 Hz. NSF #1245573.

Reply to Comment on ‘The motion of an arbitrarily rotating spherical projectile and its application to ball games’

NASA Astrophysics Data System (ADS)

Robinson, Garry; Robinson, Ian

2014-06-01

Jensen (2014 Phys. Scr. 89 067001) presents arguments that the expressions that we have used in our recent paper (Robinson and Robinson 2013 Phys. Scr. 88 018101) for the lift force and possibly the drag force acting on a rotating spherical projectile are dimensionally incorrect and therefore cannot be valid. We acknowledge that the alternative equations suggested by Jensen are dimensionally correct, and may well be borne out by future experimental results. However, we demonstrate that our equations are in fact also dimensionally correct, the key concept being that of having the appropriate dimensions for the multiplying constants, an extensively used practice with experimentally determined laws. After a detailed discussion of the situation, a simple illustrative example of Hooke's law for the restoring force, F, due to a mass attached to a spring displaced by a distance x from its equilibrium position is presented, where the spring constant, k, has such units as to render the equation dimensionally correct. Finally we discuss the implications of some relevant existing experimental results for the lift force.

Finding the Effective Mass and Spring Constant of a Force Probe from Simple Harmonic Motion

NASA Astrophysics Data System (ADS)

Greene, Nathaniel R.; Gill, Tom; Eyerly, Stephen

2016-03-01

Force probes are versatile tools in the physics lab, but their internal workings can introduce artifacts when measuring rapidly changing forces. The Dual-Range Force Sensor by Vernier (Fig. 1) uses strain gage technology to measure force, based on the bending of a beam. Strain gages along the length of the beam change resistance as the beam bends (Fig. 2). The elasticity of the beam leads to oscillations that persist after being excited by an impulsive force. How quickly the force probe freely returns to zero is thus related to the rigidity of the beam and the total mass attached to it. By varying the added mass and measuring the resulting frequency of the probe's internal free oscillations, the effective mass and spring constant of the probe's moveable parts can be found. Weighing of the probe parts and conducting a Hooke's law experiment provide static verification of these parameters. Study of the force sensor's behavior helps students to learn about damped harmonic motion, mathematical modeling, and the limitations of measuring devices.

Direct manipulation of metallic nanosheets by shear force microscopy.

PubMed

Bi, Z; Cai, W; Wang, Y; Shang, G

2018-05-15

Micro/nanomanipulation is a rapidly growing technology and holds promising applications in various fields, including photonic/electronic devices, chemical/biosensors etc. In this work, we present that shear force microscopy (ShFM) can be exploited to manipulate metallic nanosheets besides imaging. The manipulation is realized via controlling the shear force sensor probe position and shear force magnitude based on our homemade ShFM system under an optical microscopy for in situ observation. The main feature of the ShFM system is usage of a piezoelectric bimorph sensor, which has the ability of self-excitation and detection. Moreover, the shear force magnitude as a function of the spring constant of the sensor and setpoint is obtained, which indicates that operation modes can be switched between imaging and manipulation through designing the spring constant before experiment and changing the setpoint during manipulation process, respectively. We believe that this alternative manipulation technique could be used to assemble other nanostructures with different shapes, sizes and compositions for new properties and wider applications. © 2018 The Authors Journal of Microscopy © 2018 Royal Microscopical Society.

A low power, microvalve regulated architecture for drug delivery systems.

PubMed

Evans, Allan Thomas; Park, Jong M; Chiravuri, Srinivas; Gianchandani, Yogesh B

2010-02-01

This paper describes an actively-controlled architecture for drug delivery systems that offers high performance and volume efficiency through the use of micromachined components. The system uses a controlled valve to regulate dosing by throttling flow from a mechanically pressurized reservoir, thereby eliminating the need for a pump. To this end, the valve is fabricated from a glass wafer and silicon-on-insulator wafer for sensor integration. The valve draws a maximum power of 1.68 μW| (averaged over time); with the existing packaging scheme, it has a volume of 2.475 cm3. The reservoirs are assembled by compressing polyethylene terephthalate polymer balloons with metal springs. The metal springs are fabricated from Elgiloy® using photochemical etching. The springs pressurize the contents of 37 mLchambers up to 15 kPa. The system is integrated with batteries and a control circuit board within a 113 cm3 metal casing. This system has been evaluated in different control modes to mimic clinical applications. Bolus deliveries of1.5 mL have been regulated as well as continuous flows of 0.15 mL/day with accuracies of 3.22%. The results suggest that this device can be used in an implant to regulate intrathecal drug delivery

Dynamics in cyanobacterial communities from a relatively stable environment in an urbanised area (ambient springs in Central Poland).

PubMed

Nowicka-Krawczyk, Paulina; Żelazna-Wieczorek, Joanna

2017-02-01

Ambient springs are often cited as an example of an ecosystem with stable environmental conditions. A static biotope fosters the development of constant communities with a stable qualitative and relatively stable quantitative structure. Two years of studying cyanobacteria in different microhabitats of the rheocrenic and limnocrenic ambient springs located in urban areas showed that there is a high degree of cyanobacterial diversity and spatial and seasonal dynamics in communities. Spatial heterogeneity in relation to the type of spring and the type of microhabitat is reflected not only by a change in the quantitative structure (the number of species and their biomass), but also by a change in the composition of species. Seasonal changes depended on the type of spring and the type of microhabitat, where weather conditions influenced the communities by different degrees. Cyanobacterial communities of limnocrenes were more diverse in terms of composition and biomass, but they revealed a low seasonal dynamic in contrast to the communities of rheocrenes. The classification of springs based on their environmental conditions revealed that some springs were similar. The resemblance stemmed from the origin of human impact, which was reflected to a high degree in changes in the natural hydrochemical conditions of the springs. For the purpose of understanding which environmental factors had the greatest influence on cyanobacterial communities, a BIO-ENV procedure was performed. The procedure revealed that of most importance was a group of ions not related to the nature of the spring environment - NH 4 + , NO 2 - , NO 3 - , and PO 4 3- . The presence of these ions in groundwater was a result of direct and indirect human activity in the area of aquifers. The dynamics in communities in the studied springs were accelerated by human impact and weather conditions. Copyright © 2016 Elsevier B.V. All rights reserved.

Responses of ecosystem water use efficiency to spring snow and summer water addition with or without nitrogen addition in a temperate steppe

PubMed Central

Zhai, Penghui; Huang, Jianhui; Zhao, Xiang; Dong, Kuanhu

2018-01-01

Water use efficiency (WUE) is an important indicator of ecosystem functioning but how ecosystem WUE responds to climate change including precipitation and nitrogen (N) deposition increases is still unknown. To investigate such responses, an experiment with a randomized block design with water (spring snowfall or summer water addition) and nitrogen addition was conducted in a temperate steppe of northern China. We investigated net ecosystem CO2 production (NEP), gross ecosystem production (GEP) and evapotranspiration (ET) to calculate ecosystem WUE (WUEnep = NEP/ET or WUEgep = GEP/ET) under spring snow and summer water addition with or without N addition from 2011 to 2013. The results showed that spring snow addition only had significant effect on ecosystem WUE in 2013 and summer water addition showed positive effect on ecosystem WUE in 2011 and 2013, as their effects on NEP and GEP is stronger than ET. N addition increased ecosystem WUE in 2012 and 2013 both in spring snow addition and summer water addition for its increasing effects on NEP and GEP but no effect on ET. Summer water addition had less but N addition had greater increasing effects on ecosystem WUE as natural precipitation increase indicating that natural precipitation regulates ecosystem WUE responses to water and N addition. Moreover, WUE was tightly related with atmospheric vapor-pressure deficit (VPD), photosynthetic active radiation (PAR), precipitation and soil moisture indicating the regulation of climate drivers on ecosystem WUE. In addition, it also was affected by aboveground net primary production (ANPP). The study suggests that ecosystem WUE responses to water and N addition is determined by the change in carbon process rather than that in water process, which are regulated by climate change in the temperate steppe of northern China. PMID:29529082

Responses of ecosystem water use efficiency to spring snow and summer water addition with or without nitrogen addition in a temperate steppe.

PubMed

Zhang, Xiaolin; Zhai, Penghui; Huang, Jianhui; Zhao, Xiang; Dong, Kuanhu

2018-01-01

Water use efficiency (WUE) is an important indicator of ecosystem functioning but how ecosystem WUE responds to climate change including precipitation and nitrogen (N) deposition increases is still unknown. To investigate such responses, an experiment with a randomized block design with water (spring snowfall or summer water addition) and nitrogen addition was conducted in a temperate steppe of northern China. We investigated net ecosystem CO2 production (NEP), gross ecosystem production (GEP) and evapotranspiration (ET) to calculate ecosystem WUE (WUEnep = NEP/ET or WUEgep = GEP/ET) under spring snow and summer water addition with or without N addition from 2011 to 2013. The results showed that spring snow addition only had significant effect on ecosystem WUE in 2013 and summer water addition showed positive effect on ecosystem WUE in 2011 and 2013, as their effects on NEP and GEP is stronger than ET. N addition increased ecosystem WUE in 2012 and 2013 both in spring snow addition and summer water addition for its increasing effects on NEP and GEP but no effect on ET. Summer water addition had less but N addition had greater increasing effects on ecosystem WUE as natural precipitation increase indicating that natural precipitation regulates ecosystem WUE responses to water and N addition. Moreover, WUE was tightly related with atmospheric vapor-pressure deficit (VPD), photosynthetic active radiation (PAR), precipitation and soil moisture indicating the regulation of climate drivers on ecosystem WUE. In addition, it also was affected by aboveground net primary production (ANPP). The study suggests that ecosystem WUE responses to water and N addition is determined by the change in carbon process rather than that in water process, which are regulated by climate change in the temperate steppe of northern China.

[Effect of light regimens on the age dynamics of estrous function and serum prolactin level in rats].

PubMed

Vinogradova, I A; Chernova, I V

2006-01-01

The effect of different light regimens (standard 12 h. light : 12 h. darkness LD; 24-hour constant light LL, light deprivation DD, natural light regimen of the North-West of Russia NL) on the age dynamics of estrous function and on the serum prolactin in female LIO rats has been studied for two years. The rats were maintained at the one of above-mentioned regimes from the age of 25 days. The cytological monitoring of the estrous cycle was conducted every three months. The level of prolactin was studied at the age of 6, 12, 18 and 24 months. It has been found out that the regimen of constant light (LL) and the spring-summer period lead to earlier maturation, premature age-related changes of the rats' estrous cycle and to the increase of the level of serum prolactin in comparison with those in rats kept at the LD regimen. Light deprivation (DD) leads to the opposite changes. It has been noted that the exposure to constant light during the whole year is accompanied by more expressed and earlier developed age-related changes of estrous cycle in comparison with the natural light of the North-West of Russia with its peculiar year photoperiodicity (short day in autumn-winter period and white nights in spring-summer period).

Determination of the force constant of a single-beam gradient trap by measurement of backscattered light

NASA Astrophysics Data System (ADS)

Friese, M. E. J.; Rubinsztein-Dunlop, H.; Heckenberg, N. R.; Dearden, E. W.

1996-12-01

A single-beam gradient trap could potentially be used to hold a stylus for scanning force microscopy. With a view to development of this technique, we modeled the optical trap as a harmonic oscillator and therefore characterized it by its force constant. We measured force constants and resonant frequencies for 1 4- m-diameter polystyrene spheres in a single-beam gradient trap using measurements of backscattered light. Force constants were determined with both Gaussian and doughnut laser modes, with powers of 3 and 1 mW, respectively. Typical values for spring constants were measured to be between 10 6 and 4 10 6 N m. The resonant frequencies of trapped particles were measured to be between 1 and 10 kHz, and the rms amplitudes of oscillations were estimated to be around 40 nm. Our results confirm that the use of the doughnut mode for single-beam trapping is more efficient in the axial direction.

Shape memory thermal conduction switch

NASA Technical Reports Server (NTRS)

Krishnan, Vinu (Inventor); Vaidyanathan, Rajan (Inventor); Notardonato, William U. (Inventor)

2010-01-01

A thermal conduction switch includes a thermally-conductive first member having a first thermal contacting structure for securing the first member as a stationary member to a thermally regulated body or a body requiring thermal regulation. A movable thermally-conductive second member has a second thermal contacting surface. A thermally conductive coupler is interposed between the first member and the second member for thermally coupling the first member to the second member. At least one control spring is coupled between the first member and the second member. The control spring includes a NiTiFe comprising shape memory (SM) material that provides a phase change temperature <273 K, a transformation range <40 K, and a hysteresis of <10 K. A bias spring is between the first member and the second member. At the phase change the switch provides a distance change (displacement) between first and second member by at least 1 mm, such as 2 to 4 mm.

Comportement d'une source karstique soumise à une sécheresse prolongée : la source Bittit (Maroc)

NASA Astrophysics Data System (ADS)

Amraoui, Fouad; Razack, Moumtaz; Bouchaou, Lhoussaine

2004-09-01

The behaviour of a karstic spring (Bittit spring, Middle Atlas, Morocco) subjected to a prolonged drought (>20 yr), is analysed using spring hydrographs analysis methods and correlation and spectral methods. Two series of discharges, corresponding to a normal rainfall period and a drought period, are analysed. The results show that the karstic system is inertial, with very significant storage. However, in spite of the great regulating capacity of the storage, the long drought period significantly reduced the spring discharges, due to less diversified inputs, and to the karstic system storage depletion. To cite this article: F. Amraoui et al., C. R. Geoscience 336 (2004).

The role of tributary mixing in chemical variations at a karst spring, Milandre, Switzerland

NASA Astrophysics Data System (ADS)

Perrin, J.; Jeannin, P.-Y.; Cornaton, F.

2007-01-01

SummarySolute concentration variations during flood events were investigated in a karst aquifer of the Swiss Jura. Observations were made at the spring, and at the three main subterraneous tributaries feeding the spring. A simple transient flow and transport numerical model was able to reproduce chemographs and hydrographs observed at the spring, as a result of a mixing of the concentration and discharge of the respective tributaries. Sensitivity analysis carried out with the model showed that it is possible to produce chemical variations at the spring even if all tributaries have constant (but different for each of them) solute concentrations. This process is called tributary mixing. The good match between observed and modelled curves indicate that, in the phreatic zone, tributary mixing is probably an important process that shapes spring chemographs. Chemical reactions and other mixing components (e.g. from low permeability volumes) have a limited influence. Dissolution-related (calcium, bicarbonate, specific conductance) and pollution-related parameters (nitrate, chloride, potassium) displayed slightly different behaviours: during moderate flood events, the former showed limited variations compared to the latter. During large flood events, both presented chemographs with significant changes. No significant event water participates in moderate flood events and tributary mixing will be the major process shaping chemographs. Variations are greater for parameters with higher spatial variability (e.g. pollution-related). Whereas for large flood events, the contribution of event water becomes significant and influences the chemographs of all the parameters. As a result, spring water vulnerability to an accidental pollution is low during moderate flood events and under base flow conditions. It strongly increases during large flood events, because event water contributes to the spring discharge.

The springs of Lake Pátzcuaro: chemistry, salt-balance, and implications for the water balance of the lake

USGS Publications Warehouse

Bischoff, James L.; Israde-Alcántara, Isabel; Garduno-Monroy, Victor H.; Shanks, Wayne C.

2004-01-01

Lake Pa??tzcuaro, the center of the ancient Tarascan civilization located in the Mexican altiplano west of the city of Morelia, has neither river input nor outflow. The relatively constant lake-salinity over the past centuries indicates the lake is in chemical steady state. Springs of the south shore constitute the primary visible input to the lake, so influx and discharge must be via sub-lacustrine ground water. The authors report on the chemistry and stable isotope composition of the springs, deeming them representative of ground-water input. The springs are dominated by Ca, Mg and Na, whereas the lake is dominated by Na. Combining these results with previously published precipitation/rainfall measurements on the lake, the authors calculate the chemical evolution from spring water to lake water, and also calculate a salt balance of the ground-water-lake system. Comparing Cl and ??18O compositions in the springs and lake water indicates that 75-80% of the spring water is lost evaporatively during evolution toward lake composition. During evaporation Ca and Mg are lost from the water by carbonate precipitation. Each liter of spring water discharging into the lake precipitates about 18.7 mg of CaCO3. Salt balance calculations indicate that ground water input to the lake is 85.9??106 m3/a and ground water discharge from the lake is 23.0??106 m3/a. Thus, the discharge is about 27% of the input, with the rest balanced by evaporation. A calculation of time to reach steady-state ab initio indicates that the Cl concentration of the present day lake would be reached in about 150 a. ?? 2004 Elsevier Ltd. All rights reserved.

Portrait of a Geothermal Spring, Hunter's Hot Springs, Oregon.

PubMed

Castenholz, Richard W

2015-01-27

Although alkaline Hunter's Hot Springs in southeastern Oregon has been studied extensively for over 40 years, most of these studies and the subsequent publications were before the advent of molecular methods. However, there are many field observations and laboratory experiments that reveal the major aspects of the phototrophic species composition within various physical and chemical gradients of these springs. Relatively constant temperature boundaries demark the upper boundary of the unicellular cyanobacterium, Synechococcus at 73-74 °C (the world-wide upper limit for photosynthesis), and 68-70 °C the upper limit for Chloroflexus. The upper limit for the cover of the filamentous cyanobacterium, Geitlerinema (Oscillatoria) is at 54-55 °C, and the in situ lower limit at 47-48 °C for all three of these phototrophs due to the upper temperature limit for the grazing ostracod, Thermopsis. The in situ upper limit for the cyanobacteria Pleurocapsa and Calothrix is at ~47-48 °C, which are more grazer-resistant and grazer dependent. All of these demarcations are easily visible in the field. In addition, there is a biosulfide production in some sections of the springs that have a large impact on the microbiology. Most of the temperature and chemical limits have been explained by field and laboratory experiments.

Portrait of a Geothermal Spring, Hunter’s Hot Springs, Oregon

PubMed Central

Castenholz, Richard W.

2015-01-01

Although alkaline Hunter’s Hot Springs in southeastern Oregon has been studied extensively for over 40 years, most of these studies and the subsequent publications were before the advent of molecular methods. However, there are many field observations and laboratory experiments that reveal the major aspects of the phototrophic species composition within various physical and chemical gradients of these springs. Relatively constant temperature boundaries demark the upper boundary of the unicellular cyanobacterium, Synechococcus at 73–74 °C (the world-wide upper limit for photosynthesis), and 68–70 °C the upper limit for Chloroflexus. The upper limit for the cover of the filamentous cyanobacterium, Geitlerinema (Oscillatoria) is at 54–55 °C, and the in situ lower limit at 47–48 °C for all three of these phototrophs due to the upper temperature limit for the grazing ostracod, Thermopsis. The in situ upper limit for the cyanobacteria Pleurocapsa and Calothrix is at ~47–48 °C, which are more grazer-resistant and grazer dependent. All of these demarcations are easily visible in the field. In addition, there is a biosulfide production in some sections of the springs that have a large impact on the microbiology. Most of the temperature and chemical limits have been explained by field and laboratory experiments. PMID:25633225

Heat tolerance and expression of protein synthesis elongation factors, EF-Tu and EF-1a, in spring wheat

USDA-ARS?s Scientific Manuscript database

Protein elongation factors, EF-Tu and EF-1a, have been implicated in cell response to heat stress. In spring wheat, EF-Tu displays chaperone activity and reduces thermal aggregation of Rubisco activase. Similarly, in mammalian cells, EF-1a displays chaperone-like activity and regulates the expressio...

Design and fabrication of advanced fiber alignment structures for field-installable fiber connectors

NASA Astrophysics Data System (ADS)

Van Erps, Jürgen; Vervaeke, Michael; Sánchez Martínez, Alberto; Beri, Stefano; Debaes, Christof; Watté, Jan; Thienpont, Hugo

2012-06-01

Fiber-To-The-Home (FTTH) networks have been adopted as a potential replacement of traditional electrical connections for the 'last mile' transmission of information at bandwidths over 1Gb/s. However, the success and adoption of optical access networks critically depend on the quality and reliability of connections between optical fibers. In particular a further reduction of insertion loss of field-installable connectors must be achieved without a significant increase in component cost. This requires precise alignment of fibers that can differ in terms of ellipticity, eccentricity or diameter and seems hardly achievable using today's widespread ferrule-based alignment systems. Novel low-cost structures for bare fiber alignment with outstanding positioning accuracies are strongly desired as they would allow reducing loss beyond the level achievable with ferrule-bore systems. However, the realization of such alignment system is challenging as it should provide sufficient force to position the fiber with sub-micron accuracy required in positioning the fiber. In this contribution we propose, design and prototype a bare-fiber alignment system which makes use of deflectable/compressible micro-cantilevers. Such cantilevers behave as springs and provide self-centering functionality to the structure. Simulations of the mechanical properties of the cantilevers are carried out in order to get an analytical approximation and a mathematical model of the spring constant and stress in the structure. Elastic constants of the order of 104 to 105N/m are found out to be compatible with a proof stress of 70 MPa. Finally a first self-centering structure is prototyped in PMMA using our Deep Proton Writing technology. The spring constants of the fabricated cantilevers are in the range of 4 to 6 × 104N/m and the stress is in the range 10 to 20 MPa. These self-centering structures have the potential to become the basic building blocks for a new generation of field-installable connectors.

Seasonal changes of nucleotides in mussel (Mytilus galloprovincialis) mantle tissue.

PubMed

Blanco, S L; Suárez, M P; San Juan, F

2006-03-01

Seasonal variations of nucleotides in Mytilus galloprovincialis mantle tissue were analyzed. Separation and quantification was achieved by reversed-phase high-performance liquid chromatography. Total nucleotides show a pronounced seasonal variation with maximum and minimum values in autumn and spring, respectively. Adenine nucleotides accounted for the major part in spring and summer, guanosine and cytidine nucleotides in winter; uridine nucleotides were relatively constant throughout the year. Their inverse variation suggests inter-conversion among them and the maintenance of the potential cell energy in winter by other triphosphate nucleotides different from ATP. These results reflect environmental and nutritional conditions, and also the reserves and gametogenic cycles taking place in M. galloprovincialis mantle tissue.

A simple accurate chest-compression depth gauge using magnetic coils during cardiopulmonary resuscitation

NASA Astrophysics Data System (ADS)

Kandori, Akihiko; Sano, Yuko; Zhang, Yuhua; Tsuji, Toshio

2015-12-01

This paper describes a new method for calculating chest compression depth and a simple chest-compression gauge for validating the accuracy of the method. The chest-compression gauge has two plates incorporating two magnetic coils, a spring, and an accelerometer. The coils are located at both ends of the spring, and the accelerometer is set on the bottom plate. Waveforms obtained using the magnetic coils (hereafter, "magnetic waveforms"), which are proportional to compression-force waveforms and the acceleration waveforms were measured at the same time. The weight factor expressing the relationship between the second derivatives of the magnetic waveforms and the measured acceleration waveforms was calculated. An estimated-compression-displacement (depth) waveform was obtained by multiplying the weight factor and the magnetic waveforms. Displacements of two large springs (with similar spring constants) within a thorax and displacements of a cardiopulmonary resuscitation training manikin were measured using the gauge to validate the accuracy of the calculated waveform. A laser-displacement detection system was used to compare the real displacement waveform and the estimated waveform. Intraclass correlation coefficients (ICCs) between the real displacement using the laser system and the estimated displacement waveforms were calculated. The estimated displacement error of the compression depth was within 2 mm (<1 standard deviation). All ICCs (two springs and a manikin) were above 0.85 (0.99 in the case of one of the springs). The developed simple chest-compression gauge, based on a new calculation method, provides an accurate compression depth (estimation error < 2 mm).

36 CFR 21.3 - Use of thermal water.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 36 Parks, Forests, and Public Property 1 2012-07-01 2012-07-01 false Use of thermal water. 21.3 Section 21.3 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR HOT SPRINGS NATIONAL PARK; BATHHOUSE REGULATIONS § 21.3 Use of thermal water. (a) The use of the thermal waters of Hot Springs National Park, for...

36 CFR 21.3 - Use of thermal water.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 36 Parks, Forests, and Public Property 1 2014-07-01 2014-07-01 false Use of thermal water. 21.3 Section 21.3 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR HOT SPRINGS NATIONAL PARK; BATHHOUSE REGULATIONS § 21.3 Use of thermal water. (a) The use of the thermal waters of Hot Springs National Park, for...

Pattern and process of clonal growth in a common cattail (Typha latifolia L. ) population

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

Dickerman, J.A.

1982-01-01

A detailed analysis of individually identified Typha latifolia shoots quantified the births, deaths, life histories and productivities of the shoots. Three levels of plant structure were addressed: Inter-shoot relationships, individual shoot behavior and leaf dynamics. Shoots emerged in three major emergence pulses each year, and were grouped by these pulses into three major cohorts. The first cohort emerged in early spring, grew throughout the growing season, and died in late autumn. The second cohort emerged in midsummer; 70 to 80 percent of these shoots died in autumn, while the remainder resumed growth in the following spring. The third cohort emergedmore » in late summer and early autumn; 80 to 90 percent of all third cohort shoots resumed growth the following spring. An intrinsic or self-regulation of density through reallocation of assimilates between shoots and rhizomes adequately explained the density patterns. This regulation is based on the growth pattern and the differing roles of the cohorts: The first and third cohorts are predominately regenerative, while the second cohort is proliferative, and fills in shoot density if, in early spring, density is below a shoot saturation level that apparently effectively holds marsh space.« less

Machine finishes balls to high degree of roundness

NASA Technical Reports Server (NTRS)

Angele, W.; Hill, J. P., Jr.

1972-01-01

Machine was developed to finish ball to roundness within 12.5 nm (half a microinch) from any types of hard material. Grinding and polishing to this tolerance is accomplished by lapping elements on four to six motor-driven spindles. Spindles are adjustably spring-loaded to ensure constant contact pressure on ball and are driven by variable speed electric motors.

Biogeographic congruency among bacterial communities from terrestrial sulfidic springs

PubMed Central

Headd, Brendan; Engel, Annette S.

2014-01-01

Terrestrial sulfidic springs support diverse microbial communities by serving as stable conduits for geochemically diverse and nutrient-rich subsurface waters. Microorganisms that colonize terrestrial springs likely originate from groundwater, but may also be sourced from the surface. As such, the biogeographic distribution of microbial communities inhabiting sulfidic springs should be controlled by a combination of spring geochemistry and surface and subsurface transport mechanisms, and not necessarily geographic proximity to other springs. We examined the bacterial diversity of seven springs to test the hypothesis that occurrence of taxonomically similar microbes, important to the sulfur cycle, at each spring is controlled by geochemistry. Complementary Sanger sequencing and 454 pyrosequencing of 16S rRNA genes retrieved five proteobacterial classes, and Bacteroidetes, Chlorobi, Chloroflexi, and Firmicutes phyla from all springs, which suggested the potential for a core sulfidic spring microbiome. Among the putative sulfide-oxidizing groups (Epsilonproteobacteria and Gammaproteobacteria), up to 83% of the sequences from geochemically similar springs clustered together. Abundant populations of Hydrogenimonas-like or Sulfurovum-like spp. (Epsilonproteobacteria) occurred with abundant Thiothrix and Thiofaba spp. (Gammaproteobacteria), but Arcobacter-like and Sulfurimonas spp. (Epsilonproteobacteria) occurred with less abundant gammaproteobacterial populations. These distribution patterns confirmed that geochemistry rather than biogeography regulates bacterial dominance at each spring. Potential biogeographic controls were related to paleogeologic sedimentation patterns that could control long-term microbial transport mechanisms that link surface and subsurface environments. Knowing the composition of a core sulfidic spring microbial community could provide a way to monitor diversity changes if a system is threatened by anthropogenic processes or climate change. PMID:25250021

A novel stiffness control method for series elastic actuator

NASA Astrophysics Data System (ADS)

Lin, Guangmo; Zhao, Xingang; Han, Jianda

2017-01-01

Compliance plays an important role in human-robot cooperation. However, fixed compliance, or fixed stiffness, is difficult to meet the growing needs of human machine collaboration. As a result, the robot actuator is demanded to be able to adjust its stiffness. This paper presents a stiffness control scheme for a single DOF series elastic actuator (SEA) with a linear spring mounted in series in the mechanism. In this proposed method, the output angle of the spring is measured and used to calculate the input angle of the spring, thus the equivalent stiffness of the robot actuator revealed to the human operator can be rendered in accordance to the desired stiffness. Since the techniques used in this method only involve the position information of the system, there is no need to install an expensive force/torque sensor on the actuator. Further, the force/torque produced by the actuator can be estimated by simply multiplying the deformation angle of the spring and its constant stiffness coefficient. The analysis of the stiffness controller is provided. Then a simulation that emulates a human operates the SEA while the stiffness controller is running is carried out and the results also validate the proposed method.

Model-based interpretation of sediment concentration and vertical flux measurements in a shallow estuarine environment

USGS Publications Warehouse

Brand, Andreas; Lacy, Jessica R.; Gladding, Steve; Holleman, Rusty; Stacey, Mark

2015-01-01

A one-dimensional numerical model describing tidally varying vertical mixing and settling was used to interpret sediment concentrations and vertical fluxes observed in the shoals of South San Francisco Bay by two acoustic Doppler velocimeters (ADVs) at elevations of 0.36 m and 0.72 m above bed. Measured sediment concentrations changed by up to 100 g m−3 over the semidiurnal tidal cycle. These dynamics were dominated by local resuspension and settling. Multiple particle class models suggested the existence of a class with fast settling velocities (ws of 9.0 × 10−4 m s−1 in spring and 5.8 × 10−4 m s−1 in fall) and a slowly settling particle fraction (ws of <1 × 10−7 m s−1 in spring and 1.4 × 10−5 m s−1 in fall). Modeled concentrations of slowly settling particles at 0.36 m were as high as 20 g m−3 during fall and varied with the spring-neap cycle while fine sediment concentrations in spring were constant around 5 g m−3. Analysis of in situ water column floc size distributions suggested that floc properties in the lower part of the water column were most likely governed by particle-size distribution on the bed and not by coagulation, validating our multiple particle size approach. A comparison of different sediment bed models with respect to model performance, sensitivity, and identifiability suggested that the use of a sediment erosion model linear in bottom shear stress τb (E = M (τb − τc)) was the most appropriate choice to describe the field observations when the critical shear stress τc and the proportionality factor M were kept constant.

Long-term climate impacts on breeding bird phenology in Pennsylvania, USA.

PubMed

McDermott, Molly E; DeGroote, Lucas W

2016-10-01

Climate change is influencing bird phenology worldwide, but we still lack information on how many species are responding over long temporal periods. We assessed how climate affected passerine reproductive timing and productivity at a constant effort mist-netting station in western Pennsylvania using a model comparison approach. Several lines of evidence point to the sensitivity of 21 breeding passerines to climate change over five decades. The trends for temperature and precipitation over 53 years were slightly positive due to intraseasonal variation, with the greatest temperature increases and precipitation declines in early spring. Regardless of broodedness, migration distance, or breeding season, 13 species hatched young earlier over time with most advancing >3 days per decade. Warm springs were associated with earlier captures of juveniles for 14 species, ranging from 1- to 3-day advancement for every 1 °C increase. This timing was less likely to be influenced by spring precipitation; nevertheless, higher rainfall was usually associated with later appearance of juveniles and breeding condition in females. Temperature and precipitation were positively related to productivity for seven and eleven species, respectively, with negative relations evident for six and eight species. We found that birds fledged young earlier with increasing spring temperatures, potentially benefiting some multibrooded species. Indeed, some extended the duration of breeding in these warm years. Yet, a few species fledged fewer juveniles in warmer and wetter seasons, indicating that expected future increases could be detrimental to locally breeding populations. Although there were no clear relationships between life history traits and breeding phenology, species-specific responses to climate found in our study provide novel insights into phenological flexibility in songbirds. Our research underscores the value of long-term monitoring studies and the importance of continuing constant effort sampling in the face of climate change. © 2016 John Wiley & Sons Ltd.

Groundwater, surface-water, and water-chemistry data, Black Mesa area, northeastern Arizona: 2011-2012

USGS Publications Warehouse

Macy, Jamie P.; Unema, Joel A.

2014-01-01

The Navajo (N) aquifer is an extensive aquifer and the primary source of groundwater in the 5,400-square-mile Black Mesa area in northeastern Arizona. Availability of water is an important issue in northeastern Arizona because of continued water requirements for industrial and municipal use by a growing population and because of low precipitation in the arid climate of the Black Mesa area. Precipitation in the area typically is between 6 and 14 inches per year. The U.S. Geological Survey water-monitoring program in the Black Mesa area began in 1971 and provides information about the long-term effects of groundwater withdrawals from the N aquifer for industrial and municipal uses. This report presents results of data collected as part of the monitoring program in the Black Mesa area from January 2011 to September 2012. The monitoring program includes measurements of (1) groundwater withdrawals, (2) groundwater levels, (3) spring discharge, (4) surface-water discharge, and (5) groundwater chemistry. In 2011, total groundwater withdrawals were 4,480 acre-ft, industrial withdrawals were 1,390 acre-ft, and municipal withdrawals were 3,090 acre-ft. Total withdrawals during 2011 were about 39 percent less than total withdrawals in 2005 because of Peabody Western Coal Company’s discontinued use of water to transport coal in a slurry. From 2010 to 2011 total withdrawals increased by 11 percent; industrial withdrawals increased by approximately 19 percent, and total municipal withdrawals increased by 8 percent. From 2011 to 2012, annually measured water levels in the Black Mesa area declined in 8 of 15 wells that were available for comparison in the unconfined areas of the N aquifer, and the median change was -0.1 feet. Water levels declined in 9 of 18 wells measured in the confined area of the aquifer. The median change for the confined area of the aquifer was 0.0 feet. From the prestress period (prior to 1965) to 2012, the median water-level change for 34 wells in both the confined and unconfined areas was -13.4 feet; the median water-level changes were -2.1 feet for 16 wells measured in the unconfined areas and -39.1 feet for 18 wells measured in the confined area. Spring flow was measured at four springs in 2012. Flow fluctuated during the period of record for Burro and Unnamed Spring near Dennehotso, but a decreasing trend was apparent at Moenkopi School Spring and Pasture Canyon Spring. Discharge at Burro Spring has remained relatively constant since it was first measured in the 1980s and discharge at Unnamed Spring near Dennehotso has fluctuated for the period of record. Trend analysis for discharge at Moenkopi and Pasture Canyon Springs yielded a slope significantly different from zero. Continuous records of surface-water discharge in the Black Mesa area were collected from streamflow-gaging stations at the following sites: Moenkopi Wash at Moenkopi 09401260 (1976 to 2010), Dinnebito Wash near Sand Springs 09401110 (1993 to 2010), Polacca Wash near Second Mesa 09400568 (1994 to 2010), and Pasture Canyon Springs 09401265 (2004 to 2010). Median winter flows (November through February) of each water year were used as an index of the amount of groundwater discharge at the above-named sites. For the period of record of each streamflow-gaging station, the median winter flows have generally remained constant, and there are no significant statistical trends in groundwater discharge. In 2012, water samples collected from 10 wells and 4 springs in the Black Mesa area were analyzed for selected chemical constituents, and the results were compared with previous analyses. Concentrations of dissolved solids, chloride, and sulfate have varied at all 10 wells for the period of record, but neither increasing nor decreasing trends over time were found. Dissolved solids, chloride, and sulfate concentrations increased at Moenkopi School Spring during the more than 12 years of record at that site. Concentrations of dissolved solids, chloride, and sulfate at Pasture Canyon Spring have not varied significantly since the early 1980s, and there is no increasing or decreasing trend in those data. Concentrations of dissolved solids, chloride, and sulfate at Burro Spring and Unnamed Spring near Dennehotso have varied for the period of record, but there is no increasing or decreasing trend in the data.

Arsenic and antimony in geothermal waters of Yellowstone National Park, Wyoming, USA

USGS Publications Warehouse

Stauffer, R.E.; Thompson, J.M.

1984-01-01

A total of 268 thermal spring samples were analyzed for total soluble As using reduced molybdenum-blue; 27 of these samples were also analyzed for total Sb using flame atomic absorption spectrometry. At Yellowstone the Cl As atomic ratio is nearly constant among neutral-alkaline springs with Cl > 100 mg L-1, and within restricted geographic areas, indicating no differential effects of adiabatic vs. conductive cooling on arsenic. The Cl As ratio increases with silica and decreases with decreasing Cl ??CO3; the latter relationship is best exemplified for springs along the extensively sampled SE-NW trend within the Lone Star-Upper-Midway Basin region. The relationship between Cl As and Cl ??CO3 at Yellowstone suggests a possible rock leaching rather than magmatic origin for much of the Park's total As flux. Condensed vapor springs are low in both As and Cl. Very high Cl As ratios ( > 1000) are associated exclusively with highly diluted (Cl < 100 mg L-1) mixed springs in the Norris and Shoshone Basins and in the Upper White Creek and Firehole Lake areas of Lower Basin. The high ratios are associated with acidity and/or oxygen and iron; they indicate precipitation of As following massive dilution of the Asbearing high-Cl parent water. Yellowstone Sb ranged from 0.009 at Mammoth to 0.166 mg L-1 at Joseph's Coat Spring. Within basins, the Cl Sb ratio increases as the Cl ??CO3 ratio decreases, in marked contrast to As. Mixed springs also have elevated Cl Sb ratios. White (1967) and Weissberg (1969) previously reported stibnite (Sb2S3), but not orpiment (As2S3), precipitating in the near surface zone of alkaline geothermal systems. ?? 1984.

Carbon Source Preference in Chemosynthetic Hot Spring Communities

PubMed Central

Urschel, Matthew R.; Kubo, Michael D.; Hoehler, Tori M.; Peters, John W.

2015-01-01

Rates of dissolved inorganic carbon (DIC), formate, and acetate mineralization and/or assimilation were determined in 13 high-temperature (>73°C) hot springs in Yellowstone National Park (YNP), Wyoming, in order to evaluate the relative importance of these substrates in supporting microbial metabolism. While 9 of the hot spring communities exhibited rates of DIC assimilation that were greater than those of formate and acetate assimilation, 2 exhibited rates of formate and/or acetate assimilation that exceeded those of DIC assimilation. Overall rates of DIC, formate, and acetate mineralization and assimilation were positively correlated with spring pH but showed little correlation with temperature. Communities sampled from hot springs with similar geochemistries generally exhibited similar rates of substrate transformation, as well as similar community compositions, as revealed by 16S rRNA gene-tagged sequencing. Amendment of microcosms with small (micromolar) amounts of formate suppressed DIC assimilation in short-term (<45-min) incubations, despite the presence of native DIC concentrations that exceeded those of added formate by 2 to 3 orders of magnitude. The concentration of added formate required to suppress DIC assimilation was similar to the affinity constant (Km) for formate transformation, as determined by community kinetic assays. These results suggest that dominant chemoautotrophs in high-temperature communities are facultatively autotrophic or mixotrophic, are adapted to fluctuating nutrient availabilities, and are capable of taking advantage of energy-rich organic substrates when they become available. PMID:25819970

Observations and analysis of a stratification-destratification event in a tropical estuary

NASA Astrophysics Data System (ADS)

Uncles, R. J.; Ong, J. E.; Gong, W. K.

1990-11-01

A data set comprising 31 continuous tidal cycles was collected in the Sungai Merbok Estuary, Malaysia, in June 1987 as part of an ecological study of nutrient fluxes from a tropical mangrove estuary. Currents, salinity and salinity stratification at a deep-channel (15 m) station near the mouth of the Merbok Estuary showed a pronounced spring-neap variability. The slow currents and weak vertical mixing at neap tides favoured the formation of a stratified water column and generated a neap-spring cycle of water column stabilization and destabilization. A strong stratification event occurred during the period of observations. This was partly driven by a modest freshwater spate which coincided with neap tides. An eddy viscosity-diffusivity model of the stratification, which assumed a constant, longitudinal salinity gradient, demonstrated a pronounced stratification-destratification cycle due to neap-spring variations in vertical mixing. Larger and more realistic stratification was modelled when the estimated, time-varying longitudinal salinity gradient was incorporated. This gradient maximized in response to the peak in freshwater runoff. The measured and modelled density-driven circulations showed qualitative similarities and were of the order of 10 cm s -1 at neap tides. The circulation was weaker during spring tides. The tidally-filtered salt transport due to vertical shear was directed up-estuary and was an order of magnitude smaller during spring tides. The results are discussed in terms of their relevance to mangrove system oceanography.

Robust stability of second-order systems

NASA Technical Reports Server (NTRS)

Chuang, C.-H.

1995-01-01

It has been shown recently how virtual passive controllers can be designed for second-order dynamic systems to achieve robust stability. The virtual controllers were visualized as systems made up of spring, mass and damping elements. In this paper, a new approach emphasizing on the notion of positive realness to the same second-order dynamic systems is used. Necessary and sufficient conditions for positive realness are presented for scalar spring-mass-dashpot systems. For multi-input multi-output systems, we show how a mass-spring-dashpot system can be made positive real by properly choosing its output variables. In particular, sufficient conditions are shown for the system without output velocity. Furthermore, if velocity cannot be measured then the system parameters must be precise to keep the system positive real. In practice, system parameters are not always constant and cannot be measured precisely. Therefore, in order to be useful positive real systems must be robust to some degrees. This can be achieved with the design presented in this paper.

Networks with fourfold connectivity in two dimensions.

PubMed

Tessier, Frédéric; Boal, David H; Discher, Dennis E

2003-01-01

The elastic properties of planar, C4-symmetric networks under stress and at nonzero temperature are determined by simulation and mean field approximations. Attached at fourfold coordinated junction vertices, the networks are self-avoiding in that their elements (or bonds) may not intersect each other. Two different models are considered for the potential energy of the elements: either Hooke's law springs or flexible tethers (square well potential). For certain ranges of stress and temperature, the properties of the networks are captured by one of several models: at large tensions, the networks behave like a uniform system of square plaquettes, while at large compressions or high temperatures, they display many characteristics of an ideal gas. Under less severe conditions, mean field models with more general shapes (parallelograms) reproduce many essential features of both networks. Lastly, the spring network expands without limit at a two-dimensional tension equal to the force constant of the spring; however, it does not appear to collapse under compression, except at zero temperature.

Nanomechanics of biocompatible hollow thin-shell polymer microspheres.

PubMed

Glynos, Emmanouil; Koutsos, Vasileios; McDicken, W Norman; Moran, Carmel M; Pye, Stephen D; Ross, James A; Sboros, Vassilis

2009-07-07

The nanomechanical properties of biocompatible thin-shell hollow polymer microspheres with approximately constant ratio of shell thickness to microsphere diameter were measured by nanocompression tests in aqueous conditions. These microspheres encapsulate an inert gas and are used as ultrasound contrast agents by releasing free microbubbles in the presence of an ultrasound field as a result of free gas leakage from the shell. The tests were performed using an atomic force microscope (AFM) employing the force-distance curve technique. An optical microscope, on which the AFM was mounted, was used to guide the positioning of tipless cantilevers on top of individual microspheres. We performed a systematic study using several cantilevers with spring constants varying from 0.08 to 2.3 N/m on a population of microspheres with diameters from about 2 to 6 microm. The use of several cantilevers with various spring constants allowed a systematic study of the mechanical properties of the microsphere thin shell at different regimes of force and deformation. Using thin-shell mechanics theory for small deformations, the Young's modulus of the thin wall material was estimated and was shown to exhibit a strong size effect: it increased as the shell became thinner. The Young's modulus of thicker microsphere shells converged to the expected value for the macroscopic bulk material. For high applied forces, the force-deformation profiles showed a reversible and/or irreversible nonlinear behavior including "steps" and "jumps" which were attributed to mechanical instabilities such as buckling events.

Parameter Estimation of Spacecraft Fuel Slosh Model

NASA Technical Reports Server (NTRS)

Gangadharan, Sathya; Sudermann, James; Marlowe, Andrea; Njengam Charles

2004-01-01

Fuel slosh in the upper stages of a spinning spacecraft during launch has been a long standing concern for the success of a space mission. Energy loss through the movement of the liquid fuel in the fuel tank affects the gyroscopic stability of the spacecraft and leads to nutation (wobble) which can cause devastating control issues. The rate at which nutation develops (defined by Nutation Time Constant (NTC can be tedious to calculate and largely inaccurate if done during the early stages of spacecraft design. Pure analytical means of predicting the influence of onboard liquids have generally failed. A strong need exists to identify and model the conditions of resonance between nutation motion and liquid modes and to understand the general characteristics of the liquid motion that causes the problem in spinning spacecraft. A 3-D computerized model of the fuel slosh that accounts for any resonant modes found in the experimental testing will allow for increased accuracy in the overall modeling process. Development of a more accurate model of the fuel slosh currently lies in a more generalized 3-D computerized model incorporating masses, springs and dampers. Parameters describing the model include the inertia tensor of the fuel, spring constants, and damper coefficients. Refinement and understanding the effects of these parameters allow for a more accurate simulation of fuel slosh. The current research will focus on developing models of different complexity and estimating the model parameters that will ultimately provide a more realistic prediction of Nutation Time Constant obtained through simulation.

Force and Stress along Simulated Dissociation Pathways of Cucurbituril-Guest Systems.

PubMed

Velez-Vega, Camilo; Gilson, Michael K

2012-03-13

The field of host-guest chemistry provides computationally tractable yet informative model systems for biomolecular recognition. We applied molecular dynamics simulations to study the forces and mechanical stresses associated with forced dissociation of aqueous cucurbituril-guest complexes with high binding affinities. First, the unbinding transitions were modeled with constant velocity pulling (steered dynamics) and a soft spring constant, to model atomic force microscopy (AFM) experiments. The computed length-force profiles yield rupture forces in good agreement with available measurements. We also used steered dynamics with high spring constants to generate paths characterized by a tight control over the specified pulling distance; these paths were then equilibrated via umbrella sampling simulations and used to compute time-averaged mechanical stresses along the dissociation pathways. The stress calculations proved to be informative regarding the key interactions determining the length-force profiles and rupture forces. In particular, the unbinding transition of one complex is found to be a stepwise process, which is initially dominated by electrostatic interactions between the guest's ammoniums and the host's carbonyl groups, and subsequently limited by the extraction of the guest's bulky bicyclooctane moiety; the latter step requires some bond stretching at the cucurbituril's extraction portal. Conversely, the dissociation of a second complex with a more slender guest is mainly driven by successive electrostatic interactions between the different guest's ammoniums and the host's carbonyl groups. The calculations also provide information on the origins of thermodynamic irreversibilities in these forced dissociation processes.

Children's Engagement within the Preschool Classroom and Their Development of Self-Regulation

ERIC Educational Resources Information Center

Williford, Amanda P.; Vick Whittaker, Jessica E.; Vitiello, Virginia E.; Downer, Jason T.

2013-01-01

This study used an observational measure to examine how individual children's engagement with teachers, peers, and tasks was associated with gains in self-regulation. A sample of 341 preschoolers was observed, and direct assessments and teacher reports of self-regulation were obtained in the fall and spring of the preschool year. Research…

Measure synchronization in a Huygens's non-dissipative two-pendulum clocks system

NASA Astrophysics Data System (ADS)

Tian, Jing; Chen, ZiChen; Qiu, HaiBo; Xi, XiaoQiang

2018-01-01

In this paper, we characterize measure synchronization (MS) in a four-degrees-of-freedom Huygens's two-pendulum clocks system. The two-pendulum clocks are connected by a massless spring with stiffness constant k. We find that with the stiffness constant k increasing, the coupled pendulums system achieves MS above a threshold value of k c . The energy characteristics of measure synchronization have been discussed, it is found that averaged energy of each pendulum system provide us an easy way to characterize MS transition. Furthermore, we discuss the dependence of the critical value for MS transition on initial conditions and the characteristic parameters of the system.

Acclimation of killifish to thermal extremes of hot spring: Transcription of gonadal and liver heat shock genes.

PubMed

Akbarzadeh, Arash; Leder, Erica H

2016-01-01

In this study, we explored the hypothesis that killifish acclimate to thermal extremes through regulation of genes involved in stress and metabolism. We examined the liver and gonadal transcription of heat shock proteins (hsp70, hsp90a, hsp90b), glucokinase (gck), and high mobility group b1 (hmgb1) protein in wild killifish species from hot springs and rivers using quantitative real-time PCR. Moreover, we exposed a river killifish species to a long-term thermal regime of hot spring (37-40°C) and examined the liver transcription of the heat shock genes. Our results showed that hot spring killifish showed a significant, strong upregulation of liver hsp90a. Moreover, the testicular transcript levels of hsp90a, hsp90b, and hsp70 were higher in hot spring killifish than the river ones. The results of the common garden experiments showed that the transcripts of hsp70, hsp90b, and hmgb1 were mildly induced (> twofold) at the time when temperature reached to 37-40°C, while the transcripts of hsp90a were strongly induced (17-fold increase). The level of hsp90a was dramatically more upregulated when fish were maintained in thermal extreme (42-fold change higher than in ambient temperature). Moreover, a significant downregulation of gck transcripts was observed at the time when temperature was raised to 37-40°C (80-fold decrease) and during exposure to long-term thermal extreme (56-fold decrease). It can be concluded that the regulation of heat shock genes particularly hsp90a might be a key factor of the acclimation of fish to high temperature environments like hot springs. Copyright © 2015 Elsevier Inc. All rights reserved.

A wide-frequency-range air-jet shaker

NASA Technical Reports Server (NTRS)

Herr, Robert W

1957-01-01

This paper presents a description of a simple air-jet shaker. Its force can be calibrated statically and appears to be constant with frequency. It is relatively easy to use, and it has essentially massless characteristics. This shaker is applied to define the unstable branch of a frequency-response curve obtained for a nonlinear spring with a single degree of freedom.

A Simple Experiment for Determining the Elastic Constant of a Fine Wire

ERIC Educational Resources Information Center

Freeman, W. Larry; Freda, Ronald F.

2007-01-01

Many general physics laboratories involve the use of springs to demonstrate Hooke's law, and much ado is made about how this can be used as a model for describing the elastic characteristics of materials at the molecular or atomic level. In recent years, the proliferation of computers, and appropriate sensors, have made it possible to demonstrate…

Numerical performance analysis of quartz tuning fork-based force sensors

NASA Astrophysics Data System (ADS)

Dagdeviren, Omur E.; Schwarz, Udo D.

2017-01-01

Quartz tuning fork-based force sensors where one prong is immobilized onto a holder while the other one is allowed to oscillate freely (‘qPlus’ configuration) are in widespread use for high-resolution scanning probe microscopy applications. Due to the small size of the tuning forks (≈3 mm) and the complexity of the sensor assemblies, the reliable and repeatable manufacturing of the sensors has been challenging. In this paper, we investigate the contribution of the amount and location of the epoxy glue used to attach the tuning fork to its holder on the sensor’s performance. Towards this end, we use finite element analysis to model the entire sensor assembly and to perform static and dynamic numerical simulations. Our analysis reveals that increasing the thickness of the epoxy layer between prong and holder results in a decrease of the sensor’s spring constant, eigenfrequency, and quality factor while showing an increasing deviation from oscillation in its primary modal shape. Adding epoxy at the sides of the tuning fork also leads to a degradation of the quality factor even though in this case, spring constant and eigenfrequency rise in tandem with a lessening of the deviation from its ideal modal shape.

Changes of Photochemical Properties of Dissolved Organic Matter During a Hydrological Year

NASA Astrophysics Data System (ADS)

Porcal, P.; Dillon, P. J.

2009-05-01

The fate of dissolved organic matter (DOM) in lakes and streams is significantly affected by photochemical transformation of DOM. A series of laboratory photochemical experiments has been conducted to describe long term changes in photochemical properties of DOM. The stream samples used in this study originated from three different watersheds in Dorset area (Ontario, Canada), the first watershed has predominantly coniferous cove, the second one is dominated by maple and birch, and a large wetland dominates to the third one. The first order kinetic constant rate was used as a suitable characteristic of photochemical properties of DOM. The higher rates were observed in samples from watershed dominated by coniferous forest while the lower rates were determined in deciduous forest. Kinetic rates from all three watersheds showed sinusoidal pattern during the hydrological year. The rates increased steadily during autumn and winter and decreased during spring and summer. The highest values were observed during the spring melt events when the fresh DOM was flushed out from terrestrial sources. The minimum rate constants were in summer when the discharge was lower. The photochemical properties of DOM changes during the hydrological year and correspond to the seasonal cycles of terrestrial organic matter.

A new phase of disordered phonons modelled by random matrices

NASA Astrophysics Data System (ADS)

Schmittner, Sebastian; Zirnbauer, Martin

2015-03-01

Starting from the clean harmonic crystal and not invoking two-level systems, we propose a model for phonons in a disordered solid. In this model the strength of mass and spring constant disorder can be increased separately. Both types of disorder are modelled by random matrices that couple the degrees of freedom locally. Treated in coherent potential approximation (CPA), the speed of sound decreases with increasing disorder until it reaches zero at finite disorder strength. There, a critical transition to a strong disorder phase occurs. In this novel phase, we find the density of states at zero energy in three dimensions to be finite, leading to a linear temperature dependence of the heat capacity, as observed experimentally for vitreous systems. For any disorder strength, our model is stable, i.e. masses and spring constants are positive, and there are no runaway dynamics. This is ensured by using appropriate probability distributions, inspired by Wishart ensembles, for the random matrices. The CPA self-consistency equations are derived in a very accessible way using planar diagrams. The talk focuses on the model and the results. The first author acknowledges financial support by the Deutsche Telekom Stiftung.

Gravity-independent constant force resistive exercise unit

NASA Technical Reports Server (NTRS)

Colosky, Jr., Paul E. (Inventor); Ruttley, Tara M. (Inventor)

2004-01-01

This invention describes a novel gravity-independent exercise unit designed for use in microgravity, or on the ground, as a means by which to counter muscle atrophy and bone degradation due to disuse or underuse. Modular resistive packs comprising constant torque springs provide constant force opposing the withdrawal of an exercise cable from the device. In addition to uses within the space program, the compact resistive packs of the CFREU allow the unit to be small enough for easy use as a home gym for personal use, or as a supplement for rehabilitation programs. Resistive packs may be changed conveniently out of the CFREU according to the desired exercise regimen. Thus, the resistive packs replace the need for expensive, heavy, and bulky traditional weight plates. The CFREU may be employed by hospitals, rehabilitation and physical therapy clinics, and other related professional businesses.

Simple constant-current-regulated power supply

NASA Technical Reports Server (NTRS)

Priebe, D. H. E.; Sturman, J. C.

1977-01-01

Supply incorporates soft-start circuit that slowly ramps current up to set point at turn-on. Supply consists of full-wave rectifier, regulating pass transistor, current feedback circuit, and quad single-supply operational-amplifier circuit providing control. Technique is applicable to any system requiring constant dc current, such as vacuum tube equipment, heaters, or battery charges; it has been used to supply constant current for instrument calibration.

Granular rheology: measuring boundary forces with laser-cut leaf springs

NASA Astrophysics Data System (ADS)

Tang, Zhu; Brzinski, Theodore A.; Daniels, Karen E.

2017-06-01

In granular physics experiments, it is a persistent challenge to obtain the boundary stress measurements necessary to provide full a rheological characterization of the dynamics. Here, we describe a new technique by which the outer boundary of a 2D Couette cell both confines the granular material and provides spatially- and temporally- resolved stress measurements. This key advance is enabled by desktop laser-cutting technology, which allows us to design and cut linearly-deformable walls with a specified spring constant. By tracking the position of each segment of the wall, we measure both the normal and tangential stress throughout the experiment. This permits us to calculate the amount of shear stress provided by basal friction, and thereby determine accurate values of μ(I).

Stress optimization of leaf-spring crossed flexure pivots for an active Gurney flap mechanism

NASA Astrophysics Data System (ADS)

Freire Gómez, Jon; Booker, Julian D.; Mellor, Phil H.

2015-04-01

The EU's Green Rotorcraft programme is pursuing the development of a functional and airworthy Active Gurney Flap (AGF) for a full-scale helicopter rotor blade. Interest in the development of this `smart adaptive rotor blade' technology lies in its potential to provide a number of aerodynamic benefits, which would in turn translate into a reduction in fuel consumption and noise levels. The AGF mechanism selected employs leaf-spring crossed flexure pivots. These provide important advantages over bearings as they are not susceptible to seizing and do not require maintenance (i.e. lubrication or cleaning). A baseline design of this mechanism was successfully tested both in a fatigue rig and in a 2D wind tunnel environment at flight-representative deployment schedules. For full validation, a flight test would also be required. However, the severity of the in-flight loading conditions would likely compromise the mechanical integrity of the pivots' leaf-springs in their current form. This paper investigates the scope for stress reduction through three-dimensional shape optimization of the leaf-springs of a generic crossed flexure pivot. To this end, a procedure combining a linear strain energy formulation, a parametric leaf-spring profile definition and a series of optimization algorithms is employed. The resulting optimized leaf-springs are proven to be not only independent of the angular rotation at which the pivot operates, but also linearly scalable to leaf-springs of any length, minimum thickness and width. Validated using non-linear finite element analysis, the results show very significant stress reductions relative to pivots with constant cross section leaf-springs, of up to as much as 30% for the specific pivot configuration employed in the AGF mechanism. It is concluded that shape optimization offers great potential for reducing stress in crossed flexure pivots and, consequently, for extending their fatigue life and/or rotational range.

Groundwater, Surface-Water, and Water-Chemistry Data, Black Mesa Area, Northeastern Arizona-2008-2009

USGS Publications Warehouse

Macy, Jamie P.

2010-01-01

The N aquifer is an extensive aquifer and the primary source of groundwater in the 5,400-square-mile Black Mesa area in northeastern Arizona. Availability of water is an important issue in northeastern Arizona because of continued water requirements for industrial and municipal use by a growing population and because of low precipitation in the arid climate of the Black Mesa area, which is typically about 6 to 14 inches per year. The U.S. Geological Survey water-monitoring program in the Black Mesa area began in 1971 and provides information about the long-term effects of groundwater withdrawals from the N aquifer for industrial and municipal uses. This report presents results of data collected as part of the monitoring program in the Black Mesa area from January 2008 to September 2009. The monitoring program includes measurements of (1) groundwater withdrawals, (2) groundwater levels, (3) spring discharge, (4) surface-water discharge, and (5) groundwater chemistry. In 2008, total groundwater withdrawals were 4,110 acre-feet, industrial withdrawals were 1,210 acre-ft, and municipal withdrawals were 2,900 acre-ft. Total withdrawals during 2008 were about 44 percent less than total withdrawals in 2005. From 2007 to 2008 total withdrawals decreased by 4 percent, industrial withdrawals increased by approximately 3 percent, but total municipal withdrawals decreased by 6 percent. From 2008 to 2009, annually measured water levels in the Black Mesa area declined in 8 of 15 wells that were available for comparison in the unconfined areas of the N aquifer, and the median change was -0.1 feet. Water levels declined in 11 of 18 wells measured in the confined area of the aquifer. The median change for the confined area of the aquifer was -0.2 feet. From the prestress period (prior to 1965) to 2009, the median water-level change for 34 wells in both the confined and unconfined area was -11.8 feet. Also, from the prestress period to 2009, the median water-level changes were -1.6 feet for 16 wells measured in the unconfined areas and -36.7 feet for 18 wells measured in the confined area. Spring flow was measured at three springs in 2009. Flow fluctuated during the period of record, but a decreasing trend was apparent at Moenkopi School Spring and Pasture Canyon Spring. Discharge at Burro spring has remained constant since it was first measured in 1998. Continuous records of surface-water discharge in the Black Mesa area were collected from streamflow-gaging stations at the following sites: Moenkopi Wash at Moenkopi 09401260 (1976 to 2008), Dinnebito Wash near Sand Springs 09401110 (1993 to 2008), Polacca Wash near Second Mesa 09400568 (1994 to 2008), and Pasture Canyon Springs 09401265 (August 2004 to 2008). Median winter flows (November through February) of each water year were used as an index of the amount of groundwater discharge at the above-named sites. For the period of record of each streamflow-gaging station, the median winter flows have generally remained constant, which suggests no change in groundwater discharge. In 2009, water samples collected from 6 wells and 3 springs in the Black Mesa area were analyzed for selected chemical constituents, and the results were compared with previous analyses. Concentrations of dissolved solids, chloride, and sulfate have varied at all 6 wells for the period of record, but neither increasing nor decreasing trends over time were found. Dissolved-solids, chloride, and sulfate concentrations increased at Moenkopi School Spring during the more than 12 years of record at that site. Concentrations of dissolved solids, chloride, and sulfate at Pasture Canyon Spring have not varied much since the early 1980s, and there is no trend in those data. Concentrations of dissolved solids, chloride, and sulfate at Burro Spring have varied for the period of record, but there is no trend in the data.

Credits for Combined Heat and Power (CHP) in Output-Based Environmental Regulations (OBR), USCHPA 2012 Spring Policy Forum (Presentation) – May 16, 2012

EPA Pesticide Factsheets

This presentation describes the importance of output-based regulations in recognizing the environmental and energy benefits of CHP, and how OBR can be designed appropriately to incorporate the characteristics of CHP systems.

Pacing the ARRA changes. Tackling the ARRA rules and regulations as they come.

PubMed

Featheringham, Meg

2010-08-01

Through the winter and spring healthcare waited for the next round of ARRA-related regulations. Now they are here, and organizations are tagged with implementing compliant programs. How do you get started when it seems that everything needs doing at once?

Concentrations of selected trace elements in mineral and spring bottled waters on the Serbian market.

PubMed

Ristić, M; Popović, I; Pocajt, V; Antanasijević, D; Perić-Grujić, A

2011-01-01

Eight selected trace elements, which are generally included in regulations, were analyzed in 23 types of bottled waters. Ten mineral and seven spring bottled waters were from the Serbian market and six mineral bottled waters were obtained in different EU countries. For the purpose of comparison, selected tap waters were also analyzed. Inductively coupled plasma mass spectrometry (ICP-MS) was used for the analysis of trace elements (arsenic, cadmium, copper, manganese, nickel, lead and antimony). Results were compared with the Serbian regulations for bottled water, EU regulations and guideline values set by the World Health Organization for drinking water. With few exceptions, the trace element levels of most bottled waters were below the guideline values. However, a higher content of antimony was observed in waters from polyethylene terephthalate (PET) containers, indicating a potential leaching of this element from the plastic packaging.

Finding the Effective Mass and Spring Constant of a Force Probe from Simple Harmonic Motion

ERIC Educational Resources Information Center

Greene, Nathaniel R.; Gill, Tom; Eyerly, Stephen

2016-01-01

Force probes are versatile tools in the physics lab, but their internal workings can introduce artifacts when measuring rapidly changing forces. The Dual-Range Force Sensor by Vernier uses strain gage technology to measure force, based on the bending of a beam. Strain gages along the length of the beam change resistance as the beam bends. The…

The Shock and Vibration Digest. Volume 16, Number 12

DTIC Science & Technology

1984-12-01

speed, spring constant of meshing gear teeth, and mass of the Dept. of Applied Mathematical Studies , Univ of rotating years. All of these factors are...interest that stress concentration factors in civil, mechanical, naval, and aeronautical Most graduate engineers have learned that conformal structural...branes. Conformal mapping has also been used Applcaton f th coforal appig tchnque recently to study the vibration characteristics of is straightforward

Groundwater, surface-water, and water-chemistry data, Black Mesa area, northeastern Arizona—2009–10

USGS Publications Warehouse

Macy, Jamie P.; Brown, Christopher R.

2011-01-01

The Navajo (N) aquifer is an extensive aquifer and the primary source of groundwater in the 5,400-square-mile Black Mesa area in northeastern Arizona. Availability of water is an important issue in northeastern Arizona because of continued water requirements for industrial and municipal use by a growing population and because of low precipitation in the arid climate of the Black Mesa area. Precipitation in the area is typically between 6 and 14 inches per year. The U.S. Geological Survey water-monitoring program in the Black Mesa area began in 1971 and provides information about the long-term effects of groundwater withdrawals from the N aquifer for industrial and municipal uses. This report presents results of data collected as part of the monitoring program in the Black Mesa area from January 2009 to September 2010. The monitoring program includes measurements of (1) groundwater withdrawals, (2) groundwater levels, (3) spring discharge, (4) surface-water discharge, and (5) groundwater chemistry. In 2009, total groundwater withdrawals were 4,230 acre-ft, industrial withdrawals were 1,390 acre-ft, and municipal withdrawals were 2,840 acre-ft. Total withdrawals during 2009 were about 42 percent less than total withdrawals in 2005 because of Peabody Western Coal Company's discontinued use of water in a coal slurry used for transporting coal. From 2008 to 2009 total withdrawals increased by 3 percent and industrial withdrawals increased by approximately 15 percent, but total municipal withdrawals decreased by 2 percent. From 2009 to 2010, annually measured water levels in the Black Mesa area declined in 7 of 16 wells that were available for comparison in the unconfined areas of the N aquifer, and the median change was 0.1 foot. Water levels declined in 12 of 18 wells measured in the confined area of the aquifer. The median change for the confined area of the aquifer was -0.3 foot. From the prestress period (prior to 1965) to 2010, the median water-level change for 34 wells in both the confined and unconfined area was -13.9 feet. Also, from the prestress period to 2009, the median water-level changes were -0.8 foot for 16 wells measured in the unconfined areas and -38.7 feet for 18 wells measured in the confined area. Spring flow was measured at four springs in 2010. Flow fluctuated during the period of record, but a decreasing trend was apparent at Moenkopi School Spring and Pasture Canyon Spring. Discharge at Burro Spring and Unnamed Spring near Dennehotso has remained relatively constant since they were first measured in the 1980s. Continuous records of surface-water discharge in the Black Mesa area were collected from streamflow-gaging stations at the following sites: Moenkopi Wash at Moenkopi 09401260 (1976 to 2009), Dinnebito Wash near Sand Springs 09401110 (1993 to 2009), Polacca Wash near Second Mesa 09400568 (1994 to 2009), and Pasture Canyon Springs 09401265 (2004 to 2009). Median winter flows (November through February) of each water year were used as an index of the amount of groundwater discharge at the above-named sites. For the period of record of each streamflow-gaging station, the median winter flows have generally remained constant, which suggests no change in groundwater discharge. In 2010, water samples collected from 11 wells and 4 springs in the Black Mesa area were analyzed for selected chemical constituents, and the results were compared with previous analyses. Concentrations of dissolved solids, chloride, and sulfate have varied at all 11 wells for the period of record, but neither increasing nor decreasing trends over time were found. Dissolved-solids, chloride, and sulfate concentrations increased at Moenkopi School Spring during the more than 12 years of record at that site. Concentrations of dissolved solids, chloride, and sulfate at Pasture Canyon Spring have not varied much since the early 1980s, and there is no increasing or decreasing trend in those data. Concentrations of dissolved solids, chloride, and sulfate at Burro Spring and Unnamed Spring near Dennehotso have varied for the period of record, but there is no increasing or decreasing trend in the data.

The Thermal Waters of Jordan

NASA Astrophysics Data System (ADS)

Sass, I.; Schäffer, R.

2012-04-01

In a recent field campaign all known natural hot spring areas of Jordan were investigated. Their hydrochemical properties including some fundamental isotopes were measured. Jordan's thermal springs can be classified into four thermal provinces (Nahr Al-Urdun, Hammamat Ma'in, Zara and Wadi Araba province), with similar hydrochemical and geologicalsettings. Thermal springs of Hammamat Ma'in and Zara province are situated on prominent faults. Reservoir temperature estimation with the Mg-corrected Na-K-Ca geothermometer indicates temperatures between 61 °C and 82 °C. Even taking into account the increased geothermal gradient at Dead Sea's east coast, the water's origin has to be considered mainly in deeper formations. Carbon dioxide, emitted by tertiary basalts situated close to the springs, may be responsible for gas lift. Mineralisation and δ18O-values indicate, that the spring water's origin is mostly fossil, i.e. not part of the global water cycle. It is shown, that ground water mining led to a shift within δ18O-ratio during the last 30 years due to a reduction of shallow water portion in addition to a dislocation of the catchment area. Ground water mining will impact the thermal spring productivity and quality anyway in the future. Present-day precipitation rates and catchment areas in Dead Sea region are by far not sufficient to explain relative high discharge. For the Hammamat Ma'in Province is documented, that discharge and maximal spring water temperatures are constant during the last 50 years, showing marginal seasonal oscillation and negligible influence by short-term climatic changes. The water characteristics of Hammamat Ma'in and Zara province are related. However, Zara waters feature systematically less ion concentration and lower temperatures due to a stronger influence of vadose water. The springs of Nahr Al-Urdun province are recharged mainly by shallow groundwater. Thus temperature and mineralisation is lower than at the springs at the Dead Sea. Thermal waters of Wadi Araba province show the lowest mineralisation due to their origin of mostly sandstones. The main ion's proportion and δ18O-ratio indicate a mixture of fossil and vadose groundwater.

Changes in DOM Character and Composition during Spring Snow Melt in the Jemez River Basin Critical Zone Observatory.

NASA Astrophysics Data System (ADS)

Thompson, M.; Olshansky, Y.; Chorover, J.

2017-12-01

Dynamics of dissolved organic matter (DOM) in stream waters are important indicators of internal processes in the critical zone, such as decomposition and mobilization of soil organic matter, hydrologic flow paths, potential for metal mobilization and nutrient redistribution. Previous studies indicate that DOM concentration was highest during peak snow melt in the La Jara catchment located in the Jemez River Basin Critical Zone Observatory (Perdrial et al., 2014). We postulate that the molecular composition and character of DOM changes with the advance of spring snow melt. Water samples were collected from two flumes located at the outlets of the La Jara Creek and from a zero order basin within this catchment through the spring snowmelt from March 1 to May 15 2017. DOM concentration increased with stream discharge. Quantification of molecular changes was conducted using Fourier transform infrared spectroscopy (FTIR), which showed the variation in carboxyl abundance (wavenumbers 1680, 1600 and 1410 cm-1) correlated with dissolved organic carbon concentration, indicating that this component is relatively a constant fraction of the organic carbon exported through the stream during spring snowmelt. In contrast, amide vibrations (3550, 1640 and 670 cm-1) were shown to decrease with the advance of spring snowmelt. This trend further corresponded to a decrease in the ratio of carboxylic acid (above) to aromatic (1622, 1490, 955 cm-1) moieties, suggesting either a flush of compounds accumulated prior to spring snow melt, or increased decomposition of plant derived material in the soil that was then transported to the stream. Aliphatic components (2965, 2925 and 2865 cm-1) decreased from the beginning to the middle of sampling period, then showed an increase toward the end of snowmelt. O-Alkyl peak (1150 and 1073 cm-1) varied without a clear trend during the spring snowmelt. These changes in O-Alkyl and aliphatic compounds may be related to microbial derived compounds and indicate changes in microbial activity during the spring snowmelt. These results will be combined with concentration discharge analysis and data from fluorescence and UV-vis spectroscopy for evaluation and modeling of CZ processes dominated by spring snowmelt.

Calculation of total free energy yield as an alternative approach for predicting the importance of potential chemolithotrophic reactions in geothermal springs.

PubMed

Dodsworth, Jeremy A; McDonald, Austin I; Hedlund, Brian P

2012-08-01

To inform hypotheses regarding the relative importance of chemolithotrophic metabolisms in geothermal environments, we calculated free energy yields of 26 chemical reactions potentially supporting chemolithotrophy in two US Great Basin hot springs, taking into account the effects of changing reactant and product activities on the Gibbs free energy as each reaction progressed. Results ranged from 1.2 × 10(-5) to 3.6 J kg(-1) spring water, or 3.7 × 10(-5) to 11.5 J s(-1) based on measured flow rates, with aerobic oxidation of CH(4) or NH4 + giving the highest average yields. Energy yields calculated without constraining pH were similar to those at constant pH except for reactions where H(+) was consumed, which often had significantly lower yields when pH was unconstrained. In contrast to the commonly used normalization of reaction chemical affinities per mole of electrons transferred, reaction energy yields for a given oxidant varied by several orders of magnitude and were more sensitive to differences in the activities of products and reactants. The high energy yield of aerobic ammonia oxidation is consistent with previous observations of significant ammonia oxidation rates and abundant ammonia-oxidizing archaea in sediments of these springs. This approach offers an additional lens through which to view the thermodynamic landscape of geothermal springs. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Evaluating the influence of shallow magma degassing on the groundwater temperature distribution in volcanic system

NASA Astrophysics Data System (ADS)

Chen, K.; Zhan, H.; Burns, E. R.; Ingebritsen, S.

2017-12-01

The temperature and geochemical composition at the springs of La Soufrière of Guadeloupe have been monitored for more than three decades since the latest major eruption in 1976-1977. The breakthrough curves (BTCs) of the chloride and temperature exhibit distinctive difference. For the proximal spring ( 75 m to the volcanic dome), the BTC of chloride is very spiky, demonstrating the pulsatory magma degassing. However, the BTC of temperature is smooth while dropping from 70 C to 20 C. For a distal spring ( 3km), the BTC of chloride shows the characteristic of advective and dispersive transport, but the BTC of temperature is nearly constant. To explain the difference between the BTCs of chloride and temperature, a semi-analytical solution is proposed to describe the heat transport in the groundwater. The model considers one-dimensional heat conduction and convection along the flowpath and one-dimensional heat conduction to vadose zone and underlying layers. It is found that the pulse signal released from the recharge face of groundwater attenuates fast with the heat flux to the adjacent layers in consideration. The thermal response of groundwater is strongly dependent on the duration of injected pulse. A one-year pulse of 90 °C will attenuate to 33 °C at the proximal spring. For the temperature of proximal spring to reach 90 °C, the pulse duration is at the timescale of thousand years.

Method and apparatus for steady-state magnetic measurement of poloidal magnetic field near a tokamak plasma

DOEpatents

Woolley, R.D.

1998-09-08

A method and apparatus are disclosed for the steady-state measurement of poloidal magnetic field near a tokamak plasma, where the tokamak is configured with respect to a cylindrical coordinate system having z, phi (toroidal), and r axes. The method is based on combining the two magnetic field principles of induction and torque. The apparatus includes a rotor assembly having a pair of inductive magnetic field pickup coils which are concentrically mounted, orthogonally oriented in the r and z directions, and coupled to remotely located electronics which include electronic integrators for determining magnetic field changes. The rotor assembly includes an axle oriented in the toroidal direction, with the axle mounted on pivot support brackets which in turn are mounted on a baseplate. First and second springs are located between the baseplate and the rotor assembly restricting rotation of the rotor assembly about its axle, the second spring providing a constant tensile preload in the first spring. A strain gauge is mounted on the first spring, and electronic means to continually monitor strain gauge resistance variations is provided. Electronic means for providing a known current pulse waveform to be periodically injected into each coil to create a time-varying torque on the rotor assembly in the toroidal direction causes mechanical strain variations proportional to the torque in the mounting means and springs so that strain gauge measurement of the variation provides periodic magnetic field measurements independent of the magnetic field measured by the electronic integrators. 6 figs.

Method and apparatus for steady-state magnetic measurement of poloidal magnetic field near a tokamak plasma

DOEpatents

Woolley, Robert D.

1998-01-01

A method and apparatus for the steady-state measurement of poloidal magnetic field near a tokamak plasma, where the tokamak is configured with respect to a cylindrical coordinate system having z, phi (toroidal), and r axes. The method is based on combining the two magnetic field principles of induction and torque. The apparatus includes a rotor assembly having a pair of inductive magnetic field pickup coils which are concentrically mounted, orthogonally oriented in the r and z directions, and coupled to remotely located electronics which include electronic integrators for determining magnetic field changes. The rotor assembly includes an axle oriented in the toroidal direction, with the axle mounted on pivot support brackets which in turn are mounted on a baseplate. First and second springs are located between the baseplate and the rotor assembly restricting rotation of the rotor assembly about its axle, the second spring providing a constant tensile preload in the first spring. A strain gauge is mounted on the first spring, and electronic means to continually monitor strain gauge resistance variations is provided. Electronic means for providing a known current pulse waveform to be periodically injected into each coil to create a time-varying torque on the rotor assembly in the toroidal direction causes mechanical strain variations proportional to the torque in the mounting means and springs so that strain gauge measurement of the variation provides periodic magnetic field measurements independent of the magnetic field measured by the electronic integrators.

Bacterial and archeal community composition in hot springs from Indo-Burma region, North-east India.

PubMed

Panda, Amrita Kumari; Bisht, Satpal Singh; De Mandal, Surajit; Kumar, Nachimuthu Senthil

2016-12-01

Bacterial and archaeal diversity of two alkaline Indian hot springs, Jakrem (Meghalaya) and Yumthang (Sikkim), were studied. Thirteen major bacterial phyla were identified of which Firmicutes, Chloroflexi and Thermi were dominant in Jakrem and Proteobacteria in Yumthang. The dominant genera were Clostridium, Chloroflexus and Meiothermus at Jakrem (water temperature 46 °C, pH 9) and Thiobacillus, Sulfuritalea at Yumthang (water temperature 39 °C, pH 8) hot springs. The four Euryarchaeota taxa that were observed in both the hot springs were Methanoculleus, Methanosaeta, Methanosarcina and Methanocorposculum. Elstera litoralis, Thiovirga sp., Turneriella sp. were observed for the first time in association with hot springs along with Tepidibacter sp., Ignavibacterium sp., Teribacillus sp. and Dechloromonas sp. Individual bacterial phyla were found to be specifically correlated with certain physico-chemical factors such as temperature, dissolved SiO 2 , elemental S, total sulphide, calcium concentrations in hot spring water. Bacterial reads involved in sulfur cycle were identified in both16S rRNA gene library and sulfur metabolism may play key physiological functions in this hot spring. Members within Desulfobacterales and Thermodesulfovibrionaceae were identified and hypothesized their role in regulating sulfur cycle. The presence of many taxonomically unsolved sequences in the 16S rRNA gene tag datasets from these hot springs could be a sign of novel microbe richness in these less known hot water bodies of Northeastern India.

Hydrological response and thermal effect of karst springs linked to aquifer geometry and recharge processes

NASA Astrophysics Data System (ADS)

Luo, Mingming; Chen, Zhihua; Zhou, Hong; Zhang, Liang; Han, Zhaofeng

2018-03-01

To be better understand the hydrological and thermal behavior of karst systems in South China, seasonal variations in flow, hydrochemistry and stable isotope ratios of five karst springs were used to delineate flow paths and recharge processes, and to interpret their thermal response. Isotopic data suggest that mean recharge elevations are 200-820 m above spring outlets. Springs that originate from high elevations have lower NO3 - concentrations than those originating from lower areas that have more agricultural activity. Measured Sr2+ concentrations reflect the strontium contents of the host carbonate aquifer and help delineate the spring catchment's saturated zone. Seasonal variations of NO3 - and Sr2+ concentrations are inversely correlated, because the former correlates with event water and the latter with baseflow. The mean annual water temperatures of springs were only slightly lower than the local mean annual surface temperature at the outlet elevations. These mean spring temperatures suggest a vertical gradient of 6 °C/vertical km, which resembles the adiabatic lapse rate of the Earth's stable atmosphere. Seasonal temperature variations in the springs are in phase with surface air temperatures, except for Heilongquan (HLQ) spring. Event-scale variations of thermal response are dramatically controlled by the circulation depth of karst systems, which determines the effectiveness of heat exchange. HLQ spring undergoes the deepest circulation depth of 820 m, and its thermal responses are determined by the thermally effective regulation processes at higher elevations and the mixing processes associated with thermally ineffective responses at lower elevations.

Fixture for holding testing transducer

DOEpatents

Wagner, T.A.; Engel, H.P.

A fixture for mounting an ultrasonic transducer against the end of a threaded bolt or stud to test the same for flaws. A base means threadedly secured to the side of the bolt has a rotating ring thereon. A post rising up from the ring (parallel to the axis of the workpiece) pivotally mounts a variable length cross arm, on the inner end of which is mounted the transducer. A spring means acts between the cross arm and the base to apply the testing transducer against the workpiece at a constant pressure. The device maintains constant for successive tests the radial and circumferential positions of the testing transducer and its contact pressure against the end of the workpiece.

Fixture for holding testing transducer

DOEpatents

Wagner, Thomas A.; Engel, Herbert P.

1984-01-01

A fixture for mounting an ultrasonic transducer against the end of a threaded bolt or stud to test the same for flaws. A base means threadedly secured to the side of the bolt has a rotating ring thereon. A post rising up from the ring (parallel to the axis of the workpiece) pivotally mounts a variable length cross arm, on the inner end of which is mounted the transducer. A spring means acts between the cross arm and the base to apply the testing transducer against the workpiece at a constant pressure. The device maintains constant for successive tests the radial and circumferential positions of the testing transducer and its contact pressure against the end of the workpiece.

Foot pedal operated fluid type exercising device

NASA Technical Reports Server (NTRS)

Crum, G. W.; Sauter, R. J. (Inventor)

1973-01-01

A foot pedal operated exercising device is reported that contains a dynamometer formed of a pair of cylinders each containing a piston. The pistons are linked to each other. The upper portions of the two cylinders are joined together by a common opening to provide a common fluid reservoir and each piston is provided with a one way check valve to maintain an adequate supply of working fluid. Fluid from the driven cylinder is transmitted to the other cylinder through separate constant force spring biased valves each valve takes the predominant portion of the pressure drop thereby providing a constant force hydraulic dynamometer. A device is provided to determine the amount of movement of piston travel.

Behavioral Regulations and Dispositional Flow in Exercise among American College Students Relative to Stages of Change and Gender

ERIC Educational Resources Information Center

Ersöz, Gözde; Eklund, Robert C.

2017-01-01

Objective: The purpose of this study was to examine behavioral regulations and dispositional flow in exercise among university students in terms of gender and stage of change. Participants: Data were collected from American college students (N = 257; M[subscript age] ± SD = 23.02 ± 4.05) in Spring 2013. Methods: Behavioral regulations and…

The dynamics and optimal control of spinning spacecraft with movable telescoping appendages. Part C: Effect of flexibility during boom deployment

NASA Technical Reports Server (NTRS)

Bainum, P. M.; James, P. K.

1977-01-01

The dynamics of a spinning symmetrical spacecraft system during the deployment (or retraction) of flexible boom-type appendages were investigated. The effect of flexibility during boom deployment is treated by modelling the deployable members as compound spherical pendula of varying length (according to a control law). The orientation of the flexible booms with respect to the hub, is described by a sequence of two Euler angles. The boom members contain a flexural stiffness which can be related to an assumed effective restoring linear spring constant, and structural damping which effects the entire system. Linearized equations of motion for this system, when the boom length is constant, involve periodic coefficients with the frequency of the hub spin. A bounded transformation is found which converts this system into a kinematically equivalent one involving only constant coefficients.

Generalized rules for the optimization of elastic network models

NASA Astrophysics Data System (ADS)

Lezon, Timothy; Eyal, Eran; Bahar, Ivet

2009-03-01

Elastic network models (ENMs) are widely employed for approximating the coarse-grained equilibrium dynamics of proteins using only a few parameters. An area of current focus is improving the predictive accuracy of ENMs by fine-tuning their force constants to fit specific systems. Here we introduce a set of general rules for assigning ENM force constants to residue pairs. Using a novel method, we construct ENMs that optimally reproduce experimental residue covariances from NMR models of 68 proteins. We analyze the optimal interactions in terms of amino acid types, pair distances and local protein structures to identify key factors in determining the effective spring constants. When applied to several unrelated globular proteins, our method shows an improved correlation with experiment over a standard ENM. We discuss the physical interpretation of our findings as well as its implications in the fields of protein folding and dynamics.

Bayes-Turchin Analysis of Overlapping L-Edges EXAFS Data of Iron

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

Rossner, H. H.; Schmitz, D.; Imperia, P.

2007-02-02

Spin polarized and spin averaged extended x-ray absorption fine structure ((M)EXAFS) data were measured at temperatures of 180 K and 296 K in the soft x-ray energy regime of the overlapping L-edges of an iron film grown on V(110). The absorption coefficients were analyzed with the Bayes-Turchin procedure. The analysis yields the correction function to the atomic-like background-absorption coefficient calculated by FEFF8 and reveals components of atomic EXAFS oscillations. The EXAFS Debye-Waller (DW) parameters were determined. Their split into a thermal and a structural contribution was not possible without theoretical input since the two temperatures in this experiment were notmore » sufficiently far apart from each other and the k range of the data was too small. The a priori values of the thermal contribution to the DW parameters were therefore derived from a force-field model with two spring constants. They were adjusted to DW parameters calculated from Born-von Karman force constants which had been obtained from inelastic neutron scattering. Those two spring constants also nicely reproduce the unprojected vibrational density of states deduced from phonon dispersion curves. The MEXAFS oscillations can be described by the rigid-band model and the L2- and L3-EXAFS components. A negative exchange-related energy is obtained by fitting the MEXAFS signal in the extended energy region. This is in contrast to the predictions of the Hedin-Lundquist functional and the Dirac-Hara functional used in the FEFF8 code.« less

Evolution of Mars' northern polar seasonal CO2 deposits: Variations in surface brightness and bulk density

NASA Astrophysics Data System (ADS)

Mount, Christopher P.; Titus, Timothy N.

2015-07-01

Small-scale variations of seasonal ice are explored at different geomorphic units on the Northern Polar Seasonal Cap (NPSC). We use seasonal rock shadow measurements, combined with visible and thermal observations, to calculate density over time. The coupling of volume density and albedo allows us to determine the microphysical state of the seasonal CO2 ice. We find two distinct end-members across the NPSC: (1) Snow deposits may anneal to form an overlying slab layer that fractures. These low-density deposits maintain relatively constant densities over springtime. (2) Porous slab deposits likely anneal rapidly in early spring and fracture in late spring. These high-density deposits dramatically increase in density over time. The end-members appear to be correlated with latitude.

Results of Accelerated Life Testing of LCLS-II Cavity Tuner Motor

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

Huque, Naeem; Daly, Edward; Pischalnikov, Yuriy

An Accelerated Life Test (ALT) of the Phytron stepper motor used in the LCLS-II cavity tuner has been conducted at JLab. Since the motor will reside inside the cryomodule, any failure would lead to a very costly and arduous repair. As such, the motor was tested for the equivalent of 30 lifetimes before being approved for use in the production cryomodules. The 9-cell LCLS-II cavity is simulated by disc springs with an equivalent spring constant. Plots of the motor position vs. tuner position ' measured via an installed linear variable differential transformer (LVDT) ' are used to measure motor motion.more » The titanium spindle was inspected for loss of lubrication. The motor passed the ALT, and is set to be installed in the LCLS-II cryomodules.« less

Evolution of Mars’ Northern Polar Seasonal CO2 deposits: variations in surface brightness and bulk density

USGS Publications Warehouse

Mount, Christopher P.; Titus, Timothy N.

2015-01-01

Small scale variations of seasonal ice are explored at different geomorphic units on the Northern Polar Seasonal Cap (NPSC). We use seasonal rock shadow measurements, combined with visible and thermal observations, to calculate density over time. The coupling of volume density and albedo allows us to determine the microphysical state of the seasonal CO2 ice. We find two distinct endmembers across the NPSC: 1) Snow deposits may anneal to form an overlying slab layer that fractures. These low density deposits maintain relatively constant densities over springtime. 2) Porous slab deposits likely anneal rapidly in early spring and fracture in late spring. These high density deposits dramatically increase in density over time. The endmembers appear to be correlated with latitude.

RESULTS OF ACCELERATED LIFE TESTING OF LCLS-II CAVITY TUNER MOTOR

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

Huque, Naeem; Daly, Edward F.; Pischalnikov, Yuriy

An Accelerated Life Test (ALT) of the Phytron stepper motor used in the LCLS-II cavity tuner has been conducted at JLab. Since the motor will reside inside the cryomodule, any failure would lead to a very costly and arduous repair. As such, the motor was tested for the equivalent of 30 lifetimes before being approved for use in the production cryomodules. The 9-cell LCLS-II cavity is simulated by disc springs with an equivalent spring constant. Plots of the motor position vs. tuner position ' measured via an installed linear variable differential transformer (LVDT) ' are used to measure motor motion.more » The titanium spindle was inspected for loss of lubrication. The motor passed the ALT, and is set to be installed in the LCLS-II cryomodules.« less

Progress Toward a Bulk Micromachined Tunneling Tip Microaccelerometer

NASA Technical Reports Server (NTRS)

Frank T. Hartley, Ben Dolgen, Paul M. Zavracky

1995-01-01

Ultrasensitive accelerometers are needed for microgravity measurement of orbital drag and active isolation systems. We have designed an accelerometer capable of measuring accelerations of the order of 10(i) g. A tunneling tip sensor can be used as a position sensor with a potential performance advantage of two orders of magnitude over capacitive sensors. In this paper, we disclose our progress in the fabrication and measurement of a bulk microaccelerometer which employs a tunneling tip. Fully assembled accelerometers consisting of four separate die have been fabricated. The device employs a unique folded spring system with a low spring constant. To protect the tunneling tip, we have employed electrostatic clamping. Stiction has not been observed, but the required clamping voltage is greater than expected. We have developed a simple model to analyze our results.

A low-cost experiment to visualise the Fourier series: video analysis of a real plucked coiled spring

NASA Astrophysics Data System (ADS)

de Jesus, V. L. B.; Haubrichs, C.; de Oliveira, A. L.; Sasaki, D. G. G.

2018-03-01

In the present work, we develop a low-cost and simple experiment to visualise Fourier’s synthesis using a short, soft, and light plastic coiled spring oscillating in a horizontal plane, and a basic camera (120 fps). It is shown that the spring obeys a linear wave differential equation, as gravitational influence is neglected. A nonlinear criterion is evaluated to determine if magnitudes of the parameters in the initial conditions satisfy the linear wave equation. Our setup promotes some desirable characteristics that make Fourier’s synthesis experiments feasible, visual, and enlightening: (i) it requires few, common, and cheap resources, and the experiment can be carried out even in a high-school laboratory; (ii) since the spring’s tension is small (∼1 N, on average), the frequencies of normal modes are low (close to 2 Hz), and therefore, it is possible to record the oscillations just with the camera and extract a considerable number of position and time data in just one cycle; (iii) when the video is loaded in the Tracker free software, it can be reproduced in slow motion. Since the frequencies involved are low, an interesting and instructive temporal sequence of images of the spring displaying the typical trapezoidal shape appears clearly; (iv) the tools associated with the Tracker software tools can yield the relevant oscillation parameters, such as the damping constant, amplitudes, frequencies, and phases; and (v) it is possible to carry out superposition of a snapshot of the spring in Tracker at any time, and to draw the related Fourier synthesis graphs. The visual match between the shape of the spring and the theoretical graph is remarkable, and can be enhanced by adding the damping term.

Sliding contact on the interface of elastic body and rigid surface using a single block Burridge-Knopoff model

NASA Astrophysics Data System (ADS)

Amireghbali, A.; Coker, D.

2018-01-01

Burridge and Knopoff proposed a mass-spring model to explore interface dynamics along a fault during an earthquake. The Burridge and Knopoff (BK) model is composed of a series of blocks of equal mass connected to each other by springs of same stiffness. The blocks also are attached to a rigid driver via another set of springs that pulls them at a constant velocity against a rigid substrate. They studied dynamics of interface for an especial case with ten blocks and a specific set of fault properties. In our study effects of Coulomb and rate-state dependent friction laws on the dynamics of a single block BK model is investigated. The model dynamics is formulated as a system of coupled nonlinear ordinary differential equations in state-space form which lends itself to numerical integration methods, e.g. Runge-Kutta procedure for solution. The results show that the rate and state dependent friction law has the potential of triggering dynamic patterns that are different from those under Coulomb law.

Identification of Object Dynamics Using Hand Worn Motion and Force Sensors

PubMed Central

Kortier, Henk G.; Schepers, H. Martin; Veltink, Peter H.

2016-01-01

Emerging microelectromechanical system (MEMS)-based sensors become much more applicable for on-body measurement purposes lately. Especially, the development of a finger tip-sized tri-axial force sensor gives the opportunity to measure interaction forces between the human hand and environmental objects. We have developed a new prototype device that allows simultaneous 3D force and movement measurements at the finger and thumb tips. The combination of interaction forces and movements makes it possible to identify the dynamical characteristics of the object being handled by the hand. With this device attached to the hand, a subject manipulated mass and spring objects under varying conditions. We were able to identify and estimate the weight of two physical mass objects (0.44 kg: 29.3%±18.9% and 0.28 kg: 19.7%±10.6%) and the spring constant of a physical spring object (16.3%±12.6%). The system is a first attempt to quantify the interactions of the hand with the environment and has many potential applications in rehabilitation, ergonomics and sports. PMID:27898040

INSTRUMENTATION AND TECHNIQUES. A SELF-CONTAINED, REGULATED, BURST-FIRING CONSTANT-CURRENT AC SHOCK GENERATOR

EPA Science Inventory

A line- and load-regulated constant-current ac shock generator has been designed for animal behavior experiments. The self-contained unit has four operating modes, amplitude adjustment, and a leakage current detection circuit. A unique feature of this generator is that the good l...

Academic Motivation and Self-Regulated Learning in Predicting Academic Achievement in College

ERIC Educational Resources Information Center

Çetin, Baris

2015-01-01

The purpose of this study was to determine whether academic motivation and academic self-regulated learning predicted students' GPAs in the Early Childhood Education Department. The study participants consisted of 166 early childhood education majors enrolled in the 2014 spring semester at Georgia Southern University, USA. Data were gathered using…

Challenging a 15-year-old claim: The North Atlantic Oscillation index as a predictor of spring migration phenology of birds.

PubMed

Haest, Birgen; Hüppop, Ommo; Bairlein, Franz

2018-04-01

Many migrant bird species that breed in the Northern Hemisphere show advancement in spring arrival dates. The North Atlantic Oscillation (NAO) index is one of the climatic variables that have been most often investigated and shown to be correlated with these changes in spring arrival. Although the NAO is often claimed to be a good predictor or even to have a marked effect on interannual changes in spring migration phenology of Northern Hemisphere breeding birds, the results on relations between spring migration phenology and NAO show a large variety, ranging from no, over weak, to a strong association. Several factors, such as geographic location, migration phase, and the NAO index time window, have been suggested to partly explain these observed differences in association. A combination of a literature meta-analysis, and a meta-analysis and sliding time window analysis of a dataset of 23 short- and long-distance migrants from the constant-effort trapping garden at Helgoland, Germany, however, paints a completely different picture. We found a statistically significant overall effect size of the NAO on spring migration phenology (coefficient = -0.14, SE = 0.054), but this on average only explains 0%-6% of the variance in spring migration phenology across all species. As such, the value and biological meaning of the NAO as a general predictor or explanatory variable for climate change effects on migration phenology of birds, seems highly questionable. We found little to no definite support for previously suggested factors, such as geographic location, migration phenology phase, or the NAO time window, to explain the heterogeneity in correlation differences. We, however, did find compelling evidence that the lack of accounting for trends in both time series has led to strongly inflated (spurious) correlations in many studies (coefficient = -0.13, SE = 0.019). © 2017 John Wiley & Sons Ltd.

Design of a constant tension thermocouple rake suitable for flame studies

NASA Technical Reports Server (NTRS)

Ahuja, Sandeep; Miller, David L.

1993-01-01

An improved, spring-loaded thermocouple rake, suitable for studying flame structure, has been designed. This design keeps the thermocouple under tension thereby ensuring that the thermocouple does not droop due to the thermal expansion of the sensing wire when inserted in the flame. The present design allows the usage of thermocouple wire as small as 0.0508 mm and relative ease in changing thermocouple wire.

Molecular mechanisms of continuous light inhibition of Atlantic salmon parr-smolt transformation

USGS Publications Warehouse

Stefansson, S.O.; Nilsen, Tom O.; Ebbesson, Lars O.E.; Wargelius, A.; Madsen, Steffen S.; Bjornsson, B. Th; McCormick, S.D.

2007-01-01

Atlantic salmon (Salmo salar) rely on changes in photoperiod for the synchronization of the developmental events constituting the parr-smolt transformation. In the absence of photoperiod cues, parr-smolt transformation is incomplete, and such 'pseudo-smolts' normally fail to adapt to seawater. The present study addresses the endocrine and molecular mechanisms controlling the development of hypo-osmoregulatory ability and how artificial photoperiod can disrupt these changes. Juvenile Atlantic salmon reared under constant light (LL) from first feeding, were separated into two groups, and exposed to either LL or simulated natural photoperiod (LDN) from October, eight months prior to the expected completion of smoltification. Juveniles reared on LL grew well, but failed to show the smolt-related reduction in condition factor in spring. Gill mRNA levels of Na+, K+-ATPase (NKA) isoform ??1a decreased in LDN fish through completion of parr-smolt transformation, while levels remained unchanged in the LL group. In contrast, ??1b expression increased 6-fold in the LDN group between February and May, again with no change in the LL group. Further, Na+, K+, 2Cl- co-transporter (NKCC) showed a transient increase in expression in smolts on LDN between February and May, while no changes in mRNA levels were seen in juveniles under LL. Consequently, gill NKA activity and NKA ?? and NKCC protein abundance were significantly lower in juveniles on LL than in smolts on LDN. LL fish in spring had lower circulating levels of thyroid hormones (THs), growth hormone (GH) and cortisol. Gill GH-receptor mRNA levels, determined by quantitative PCR, were less than 50% of controls. In contrast, circulating levels of IGF-1 and gill IGF-1 receptor expression, were comparable to controls. Our findings show that continuous light prevents the completion of parr-smolt transformation at a very basic level, disrupting the natural up-regulation of key elements of the endocrine system involved in the regulation of the parr-smolt transformation, and consequently inhibiting the smoltification-related increase in expression, abundance and activity of gill ion transport proteins. ?? 2007 Elsevier B.V. All rights reserved.

Visco-Elastic Membrane Tethers Extracted from Escherichia coli by Optical Tweezers

PubMed Central

Jauffred, Liselotte; Callisen, Thomas Hønger; Oddershede, Lene Broeng

2007-01-01

Tethers were created between a living Escherichia coli bacterium and a bead by unspecifically attaching the bead to the outer membrane and pulling it away using optical tweezers. Upon release, the bead returned to the bacterium, thus showing the existence of an elastic tether between the bead and the bacterium. These tethers can be tens of microns long, several times the bacterial length. Using mutants expressing different parts of the outer membrane structure, we have shown that an intact core lipopolysaccharide is a necessary condition for tether formation, regardless of whether the beads were uncoated polystyrene or beads coated with lectin. A physical characterization of the tethers has been performed yielding visco-elastic tether force-extension relationships: for first pull tethers, a spring constant of 10–12 pN/μm describes the tether visco-elasticity, for subsequent pulls the spring constant decreases to 6–7 pN/μm, and typical relaxation timescales of hundreds of seconds are observed. Studies of tether stability in the presence of proteases, lipases, and amylases lead us to propose that the extracted tether is primarily composed of the asymmetric lipopolysaccharide containing bilayer of the outer membrane. This unspecific tethered attachment mechanism could be important in the initiation of bacterial adhesion. PMID:17704145

[Urodynamics foundations: contractile potency and urethral doppler].

PubMed

Benítez Navío, Julio; Caballero Gómez, Pilar; Delgado Elipe, Ildefonso

2002-12-01

To calculate the bladder softening factor, elastic constant and contractile potency. For the analysis we considered bladder behavior like that of a spring. See articles 1 and 2 published in this issue. Using flowmetry, Doppler ultrasound and abdominal pressure (Transrectal pressure register catheter) an analytical solution that permits calculation of factors defining bladder behavior was looked for. Doppler ultrasound allows us to know urine velocity through the prostatic urethra and, therefore, to calculate bladder contractile potency. Equations are solved reaching an analytical solution that allows calculating those factors that define bladder behavior: Bladder contractile potency, detrusor elastic constant, considering it behaves like a spring, and calculation of muscle resistance to movement. All thanks to Doppler ultrasound that allows to know urine speed. The bladder voiding phase is defined with the aforementioned factors; storage phase behavior can be indirectly inferred. Only uroflowmetry curves, Doppler ultrasound and abdominal pressure value are used. We comply with the so called non invasive urodynamics although for us it is just another phase in the biomechanical study of the detrusor muscle. Main conclusion is the addition of Doppler ultrasound to the urodynamist armamentarium as an essential instrument for the comprehension of bladder dynamics and calculation of bladder behavior defining factors. It is not a change in the focus but in the methods, gaining knowledge and diminishing invasion.

Observations of sound-speed fluctuations in the western Philippine Sea in the spring of 2009.

PubMed

Colosi, John A; Van Uffelen, Lora J; Cornuelle, Bruce D; Dzieciuch, Matthew A; Worcester, Peter F; Dushaw, Brian D; Ramp, Steven R

2013-10-01

As an aid to understanding long-range acoustic propagation in the Philippine Sea, statistical and phenomenological descriptions of sound-speed variations were developed. Two moorings of oceanographic sensors located in the western Philippine Sea in the spring of 2009 were used to track constant potential-density surfaces (isopycnals) and constant potential-temperature surfaces (isotherms) in the depth range 120-2000 m. The vertical displacements of these surfaces are used to estimate sound-speed fluctuations from internal waves, while temperature/salinity variability along isopycnals are used to estimate sound-speed fluctuations from intrusive structure often termed spice. Frequency spectra and vertical covariance functions are used to describe the space-time scales of the displacements and spiciness. Internal-wave contributions from diurnal and semi-diurnal internal tides and the diffuse internal-wave field [related to the Garrett-Munk (GM) spectrum] are found to dominate the sound-speed variability. Spice fluctuations are weak in comparison. The internal wave and spice frequency spectra have similar form in the upper ocean but are markedly different below 170-m depth. Diffuse internal-wave mode spectra show a form similar to the GM model, while internal-tide mode spectra scale as mode number to the minus two power. Spice decorrelates rapidly with depth, with a typical correlation scale of tens of meters.

Groundwater, surface-water, and water-chemistry data, Black Mesa area, northeastern Arizona - 2010-2011

USGS Publications Warehouse

Macy, Jamie P.; Brown, Christopher R.; Anderson, Jessica R.

2012-01-01

The Navajo (N) aquifer is an extensive aquifer and the primary source of groundwater in the 5,400-square-mile Black Mesa area in northeastern Arizona. Availability of water is an important issue in northeastern Arizona because of continued water requirements for industrial and municipal use by a growing population and because of low precipitation in the arid climate of the Black Mesa area. Precipitation in the area is typically between 6 to 14 inches per year. The U.S. Geological Survey water-monitoring program in the Black Mesa area began in 1971 and provides information about the long-term effects of groundwater withdrawals from the N aquifer for industrial and municipal uses. This report presents results of data collected as part of the monitoring program in the Black Mesa area from January 2010 to September 2011. The monitoring program includes measurements of (1) groundwater withdrawals, (2) groundwater levels, (3) spring discharge, (4) surface-water discharge, and (5) groundwater chemistry. In 2010, total groundwater withdrawals were 4,040 acre-ft, industrial withdrawals were 1,170 acre-ft, and municipal withdrawals were 2,870 acre-ft. Total withdrawals during 2010 were about 42 percent less than total withdrawals in 2005 because of Peabody Western Coal Company's discontinued use of water to transport coal in a slurry. From 2009 to 2010 total withdrawals decreased by 5 percent; industrial withdrawals decreased by approximately 16 percent, and total municipal withdrawals increased by 1 percent. From 2010 to 2011, annually measured water levels in the Black Mesa area declined in 7 of 15 wells that were available for comparison in the unconfined areas of the N aquifer, and the median change was 0.0 foot. Water levels declined in 11 of 18 wells measured in the confined area of the aquifer. The median change for the confined area of the aquifer was -0.7 foot. From the prestress period (prior to 1965) to 2011, the median water-level change for 33 wells in both the confined and unconfined areas was -15.0 feet. Also, from the prestress period to 2011, the median water-level changes were -1.2 foot for 15 wells measured in the unconfined areas and -41.2 feet for 18 wells measured in the confined area. Spring flow was measured at three springs in 2011. Flow fluctuated during the period of record, but a decreasing trend was apparent at Moenkopi School Spring and Pasture Canyon Spring. Discharge at Burro Spring has remained relatively constant since it was first measured in the 1980s. Continuous records of surface-water discharge in the Black Mesa area were collected from streamflow-gaging stations at the following sites: Moenkopi Wash at Moenkopi 09401260 (1976 to 2010), Dinnebito Wash near Sand Springs 09401110 (1993 to 2010), Polacca Wash near Second Mesa 09400568 (1994 to 2010), and Pasture Canyon Springs 09401265 (2004 to 2010). Median winter flows (November through February) of each water year were used as an index of the amount of groundwater discharge at the above-named sites. For the period of record of each streamflow-gaging station, the median winter flows have generally remained constant, which suggests no change in groundwater discharge. In 2011, water samples collected from 11 wells and 4 springs in the Black Mesa area were analyzed for selected chemical constituents, and the results were compared with previous analyses. Concentrations of dissolved solids, chloride, and sulfate have varied at all 11 wells for the period of record, but neither increasing nor decreasing trends over time were found. Dissolved-solids, chloride, and sulfate concentrations increased at Moenkopi School Spring during the more than 12 years of record at that site. Concentrations of dissolved solids, chloride, and sulfate at Pasture Canyon Spring have not varied much since the early 1980s, and there is no increasing or decreasing trend in those data. Concentrations of dissolved solids, chloride, and sulfate at Burro Spring and Unnamed Spring near Dennehotso have varied for the period of record, but there is no increasing or decreasing trend in the data.

A Link between Dimerization and Autophosphorylation of the Response Regulator PhoB*

PubMed Central

Creager-Allen, Rachel L.; Silversmith, Ruth E.; Bourret, Robert B.

2013-01-01

Response regulator proteins within two-component signal transduction systems are activated by phosphorylation and can catalyze their own covalent phosphorylation using small molecule phosphodonors. To date, comprehensive kinetic characterization of response regulator autophosphorylation is limited to CheY, which follows a simple model of phosphodonor binding followed by phosphorylation. We characterized autophosphorylation of the response regulator PhoB, known to dimerize upon phosphorylation. In contrast to CheY, PhoB time traces exhibited an initial lag phase and gave apparent pseudo-first order rate constants that increased with protein concentration. Furthermore, plots of the apparent autophosphorylation rate constant versus phosphodonor concentration were sigmoidal, as were PhoB binding isotherms for the phosphoryl group analog BeF3−. Successful mathematical modeling of the kinetic data necessitated inclusion of the formation of a PhoB heterodimer (one phosphorylated and one unphosphorylated monomer) with an enhanced rate of phosphorylation. Specifically, dimerization constants for the PhoB heterodimer and homodimer (two phosphorylated monomers) were similar, but the rate constant for heterodimer phosphorylation was ∼10-fold higher than for the monomer. In a test of the model, disruption of the known PhoBN dimerization interface by mutation led to markedly slower and noncooperative autophosphorylation kinetics. Furthermore, phosphotransfer from the sensor kinase PhoR was enhanced by dimer formation. Phosphorylation-mediated dimerization allows many response regulators to bind to tandem DNA-binding sites and regulate transcription. Our data challenge the notion that response regulator dimers primarily form between two phosphorylated monomers and raise the possibility that response regulator heterodimers containing one phosphoryl group may participate in gene regulation. PMID:23760278

Force probe simulations of a reversibly rebinding system: Impact of pulling device stiffness

NASA Astrophysics Data System (ADS)

Jaschonek, Stefan; Diezemann, Gregor

2017-03-01

We present a detailed study of the parameter dependence of force probe molecular dynamics (FPMD) simulations. Using a well studied calix[4]arene catenane dimer as a model system, we systematically vary the pulling velocity and the stiffness of the applied external potential. This allows us to investigate how the results of pulling simulations operating in the constant velocity mode (force-ramp mode) depend on the details of the simulation setup. The system studied has the further advantage of showing reversible rebinding meaning that we can monitor the opening and the rebinding transition. Many models designed to extract kinetic information from rupture force distributions work in the limit of soft springs and all quantities are found to depend solely on the so-called loading rate, the product of spring stiffness and pulling velocity. This approximation is known to break down when stiff springs are used, a situation often encountered in molecular simulations. We find that while some quantities only depend on the loading rate, others show an explicit dependence on the spring constant used in the FPMD simulation. In particular, the force versus extension curves show an almost stiffness independent rupture force but the force jump after the rupture transition does depend roughly linearly on the value of the stiffness. The kinetic rates determined from the rupture force distributions show a dependence on the stiffness that can be understood in terms of the corresponding dependence of the characteristic forces alone. These dependencies can be understood qualitatively in terms of a harmonic model for the molecular free energy landscape. It appears that the pulling velocities employed are so large that the crossover from activated dynamics to diffusive dynamics takes place on the time scale of our simulations. We determine the effective distance of the free energy minima of the closed and the open configurations of the system from the barrier via an analysis of the hydrogen-bond network with results in accord with earlier simulations. We find that the system is quite brittle in the force regime monitored in the sense that the barrier is located near to the closed state.

15 CFR 922.102 - Prohibited or otherwise regulated activities.

Code of Federal Regulations, 2010 CFR

2010-01-01

... Trade (Continued) NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE OCEAN AND..., including such devices known as Hawaiian slings, pole spears, arbalettes, pneumatic and spring-loaded...

15 CFR 922.102 - Prohibited or otherwise regulated activities.

Code of Federal Regulations, 2011 CFR

2011-01-01

... Trade (Continued) NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE OCEAN AND..., including such devices known as Hawaiian slings, pole spears, arbalettes, pneumatic and spring-loaded...

40 CFR 86.519-90 - Constant volume sampler calibration.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 19 2013-07-01 2013-07-01 false Constant volume sampler calibration... Regulations for 1978 and Later New Motorcycles; Test Procedures § 86.519-90 Constant volume sampler calibration. (a) The CVS (Constant Volume Sampler) is calibrated using an accurate flowmeter and restrictor...

40 CFR 86.519-90 - Constant volume sampler calibration.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 19 2012-07-01 2012-07-01 false Constant volume sampler calibration... Regulations for 1978 and Later New Motorcycles; Test Procedures § 86.519-90 Constant volume sampler calibration. (a) The CVS (Constant Volume Sampler) is calibrated using an accurate flowmeter and restrictor...

40 CFR 86.519-90 - Constant volume sampler calibration.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 18 2011-07-01 2011-07-01 false Constant volume sampler calibration... Regulations for 1978 and Later New Motorcycles; Test Procedures § 86.519-90 Constant volume sampler calibration. (a) The CVS (Constant Volume Sampler) is calibrated using an accurate flowmeter and restrictor...

40 CFR 86.519-90 - Constant volume sampler calibration.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 19 2014-07-01 2014-07-01 false Constant volume sampler calibration... Regulations for 1978 and Later New Motorcycles; Test Procedures § 86.519-90 Constant volume sampler calibration. (a) The CVS (Constant Volume Sampler) is calibrated using an accurate flowmeter and restrictor...

40 CFR 86.519-90 - Constant volume sampler calibration.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 18 2010-07-01 2010-07-01 false Constant volume sampler calibration... Regulations for 1978 and Later New Motorcycles; Test Procedures § 86.519-90 Constant volume sampler calibration. (a) The CVS (Constant Volume Sampler) is calibrated using an accurate flowmeter and restrictor...

Shape memory alloy resetable spring lift for pedestrian protection

NASA Astrophysics Data System (ADS)

Barnes, Brian M.; Brei, Diann E.; Luntz, Jonathan E.; Strom, Kenneth; Browne, Alan L.; Johnson, Nancy

2008-03-01

Pedestrian protection has become an increasingly important aspect of automotive safety with new regulations taking effect around the world. Because it is increasingly difficult to meet these new regulations with traditional passive approaches, active lifts are being explored that increase the "crush zone" between the hood and rigid under-hood components as a means of mitigating the consequences of an impact with a non-occupant. Active lifts, however, are technically challenging because of the simultaneously high forces, stroke and quick timing resulting in most of the current devices being single use. This paper introduces the SMArt (Shape Memory Alloy ReseTable) Spring Lift, an automatically resetable and fully reusable device, which couples conventional standard compression springs to store the energy required for a hood lift, with Shape Memory Alloys actuators to achieve both an ultra high speed release of the spring and automatic reset of the system for multiple uses. Each of the four SMArt Device subsystems, lift, release, lower and reset/dissipate, are individually described. Two identical complete prototypes were fabricated and mounted at the rear corners of the hood, incorporated within a full-scale vehicle testbed at the SMARTT (Smart Material Advanced Research and Technology Transfer) lab at University of Michigan. Full operational cycle testing of a stationary vehicle in a laboratory setting confirms the ultrafast latch release, controlled lift profile, gravity lower to reposition the hood, and spring recompression via the ratchet engine successfully rearming the device for repeat cycles. While this is only a laboratory demonstration and extensive testing and development would be required for transition to a fielded product, this study does indicate that the SMArt Lift has promise as an alternative approach to pedestrian protection.

Timing of spring wild turkey hunting in relation to nest incubation

USGS Publications Warehouse

Casalena, Mary Jo; Everett, Rex; Vreeland, Wendy C.; Gregg, Ian D.; Diefenbach, Duane R.

2016-01-01

State wildlife agencies are often requested to open spring wild turkey (Meleagris gallopavo; hereafter, turkey) hunting seasons earlier to increase hunter satisfaction by hunters hearing more gobbling male turkeys. Timing of spring turkey hunting season in several states, including Pennsylvania, has been established to open, on average, near median date of incubation initiation of turkey nests. This is believed to reduce illegal and undesired hen harvest and possibly nest abandonment, while maintaining hunter satisfaction of hearing male turkeys when most hens are incubating eggs. However, Pennsylvania’s spring season structure was established in 1968. Given earlier spring phenology, and potentially more variation in spring weather due to climate change, there is concern that timing of nest incubation for turkeys in Pennsylvania could be changing. Therefore, our objective was to determine if nest incubation and opening of spring turkey hunting in Pennsylvania have continued to coincide. We attached satellite transmitters to 254 female turkeys during 2010–2014 and estimated median incubation initiation date to be 2 May, which was 2 days earlier than median date during a statewide study during 1953–1963 and 9 days earlier than during a smaller scale study in south–central Pennsylvania during 2000–2001. However, incubation initiation varied greatly among years and individual hens during all 3 studies. During 4 of 5 years of our study, Pennsylvania’s spring season opened 3 to 8 days prior to median date of incubation initiation. Over the 5 years, estimated initiation of incubation for first nesting attempts, measured from earliest date of incubation initiation to latest, was >2 months and maximum proportion of hens beginning incubation at any one time differed by several days to >1 week. Consequently, in years of late incubation, a constant season opening date set near the long-term median date of incubation initiation exposes few additional hens to risk and hunter satisfaction is likely maintained at greater levels than would be seen with a more conservative approach of opening the season later. Long-term and large scale studies using GPS transmitters that provide precise determination of incubation initiation will be useful to study environmental influences on initiation of incubation.

Seasonal differences in extinction and colonization drive occupancy dynamics of an imperilled amphibian.

PubMed

Randall, Lea A; Smith, Des H V; Jones, Breana L; Prescott, David R C; Moehrenschlager, Axel

2015-01-01

A detailed understanding of the population dynamics of many amphibian species is lacking despite concerns about declining amphibian biodiversity and abundance. This paper explores temporal patterns of occupancy and underlying extinction and colonization dynamics in a regionally imperiled amphibian species, the Northern leopard frog (Lithobates pipiens) in Alberta. Our study contributes to elucidating regional occupancy dynamics at northern latitudes, where climate extremes likely have a profound effect on seasonal occupancy. The primary advantage of our study is its wide geographic scale (60,000 km2) and the use of repeat visual surveys each spring and summer from 2009-2013. We find that occupancy varied more dramatically between seasons than years, with low spring and higher summer occupancy. Between spring and summer, colonization was high and extinction low; inversely, colonization was low and extinction high over the winter. The dynamics of extinction and colonization are complex, making conservation management challenging. Our results reveal that Northern leopard frog occupancy was constant over the last five years and thus there is no evidence of decline or recovery within our study area. Changes to equilibrium occupancy are most sensitive to increasing colonization in the spring or declining extinction in the summer. Therefore, conservation and management efforts should target actions that are likely to increase spring colonization; this could be achieved through translocations or improving the quality or access to breeding habitat. Because summer occupancy is already high, it may be difficult to improve further. Nevertheless, summer extinction could be reduced by predator control, increasing water quality or hydroperiod of wetlands, or increasing the quality or quantity of summer habitat.

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

Zhuang, Jinda; Ju, Y. Sungtaek, E-mail: just@seas.ucla.edu

One major challenge in incorporating flexible electronics or optoelectronics on curved surfaces is the requirement of significant stretchability. We report a tunable platform for incorporating flexible and yet non-stretching device layers on a hemisphere. In this configuration, an array of planar petals contractively maps onto the surface of an inflatable hemisphere through elastocapillary interactions mediated by an interface liquid. A mechanical model is developed to elucidate the dependence of the conformality of the petal structures on their elastic modulus and thickness and the liquid surface tension. The modeling results are validated against experimental results obtained using petal structures of differentmore » thicknesses, restoring elastic spring elements of different spring constants, and liquids with different surface tension coefficients. Our platform will enable facile integration of non-stretching electronic and optoelectronic components prepared using established planar fabrication techniques on tunable hemispherical surfaces.« less

THE EFFECTS OF MAINTENANCE ACTIONS ON THE PFDavg OF SPRING OPERATED PRESSURE RELIEF VALVES

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

Harris, S.; Gross, R.

2014-04-01

The safety integrity level (SIL) of equipment used in safety instrumented functions is determined by the average probability of failure on demand (PFDavg) computed at the time of periodic inspection and maintenance, i.e., the time of proof testing. The computation of PFDavg is generally based solely on predictions or estimates of the assumed constant failure rate of the equipment. However, PFDavg is also affected by maintenance actions (or lack thereof) taken by the end user. This paper shows how maintenance actions can affect the PFDavg of spring operated pressure relief valves (SOPRV) and how these maintenance actions may be accountedmore » for in the computation of the PFDavg metric. The method provides a means for quantifying the effects of changes in maintenance practices and shows how these changes impact plant safety.« less

Classical Mechanics Experiments using Wiimotes

NASA Astrophysics Data System (ADS)

Lopez, Alexander; Ochoa, Romulo

2010-02-01

The Wii, a video game console, is a very popular device. Although computationally it is not a powerful machine by today's standards, to a physics educator the controllers are its most important components. The Wiimote (or remote) controller contains a three-axis accelerometer, an infrared detector, and Bluetooth connectivity at a relatively low price. Thanks to available open source code, such as GlovePie, any PC or Laptop with Bluetooth capability can detect the information sent out by the Wiimote. We present experiments that use two or three Wiimotes simultaneously to measure the variable accelerations in two mass systems interacting via springs. Normal modes are determined from the data obtained. Masses and spring constants are varied to analyze their impact on the accelerations of the systems. We present the results of our experiments and compare them with those predicted using Lagrangian mechanics. )

The Effects of Maintenance Actions on the PFDavg of Spring Operated Pressure Relief Valves

DOE PAGES

Harris, S.; Gross, R.; Goble, W; ...

2015-12-01

The safety integrity level (SIL) of equipment used in safety instrumented functions is determined by the average probability of failure on demand (PFDavg) computed at the time of periodic inspection and maintenance, i.e., the time of proof testing. The computation of PFDavg is generally based solely on predictions or estimates of the assumed constant failure rate of the equipment. However, PFDavg is also affected by maintenance actions (or lack thereof) taken by the end user. This paper shows how maintenance actions can affect the PFDavg of spring operated pressure relief valves (SOPRV) and how these maintenance actions may be accountedmore » for in the computation of the PFDavg metric. The method provides a means for quantifying the effects of changes in maintenance practices and shows how these changes impact plant safety.« less

Adding Some Gas Can Completely Change How an Object in a Liquid-Filled Housing Responds to Vibration

NASA Astrophysics Data System (ADS)

Torczynski, J. R.; O'Hern, T. J.; Clausen, J. R.

2015-11-01

Adding a little gas can completely change the motion of an object in a liquid-filled housing during vibration. A common system exhibiting this behavior is a spring-supported piston in a liquid-filled cylinder, where the gaps between them are narrow and depend on the piston position. When gas is absent, the piston's vibrational response is highly overdamped due to forcing viscous liquid through narrow gaps. When a small amount of gas is added, Bjerknes forces cause some of the gas to migrate below the piston. The resulting two gas regions form a pneumatic spring that enables the liquid to move with the piston, with the result that very little liquid is forced through the narrow gaps. This ``Couette mode'' has low damping and thus has a strong resonance near the frequency given by the pneumatic spring constant and the piston mass. At this frequency, the piston response is large, and the nonlinearity from the gap geometry produces a net force on the piston. This ``rectified'' force can be many times the piston's weight and can cause the piston to compress its supporting spring. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Crackling to periodic transition in a granular stick-slip experiment

NASA Astrophysics Data System (ADS)

Abed Zadeh, Aghil; BaréS, Jonathan; Behringer, Robert

We perform a stick-slip experiment to characterize avalanches in time and space for granular materials. In our experiment, a constant speed stage pulls a slider which rests on a vertical bed of circular photo-elastic particles in a 2D system. The stage is connected to the slider by a spring. We measure the force on the spring by a force sensor attached to the spring. We study the avalanche size statistics, and other seismicity laws of slip avalanches. Using the power spectrum of the force signal and avalanche statistics, we analyze the effect of the loading speed and of the spring stiffness and we capture a transition from crackling to periodic regime by changing these parameters. From a more local point of view and by using a high speed camera and the photo-elastic properties of our particles, we characterize the local stress change and flow of particles during slip avalanches. By image processing, we detect the local avalanches as connected components in space and time, and we study the avalanche size probability density functions (PDF). The PDF of avalanches obey power laws both at global and local scales, but with different exponents. We try to understand the correlation of local avalanches in space and the way they coarse grain to the global avalanches. NSF Grant DMR-1206351, NASA Grant NNX15AD38G, and the William M. Keck Foundation.

Onset of photosynthesis in spring speeds up monoterpene synthesis and leads to emission bursts

PubMed Central

Porcar‐Castell, A.; Atherton, J.; Kolari, P.; Pohja, T.; Hari, P.; Nikinmaa, E.; PetÄJÄ, T.; Bäck, J.

2015-01-01

Abstract Emissions of biogenic volatile organic compounds (BVOC) by boreal evergreen trees have strong seasonality, with low emission rates during photosynthetically inactive winter and increasing rates towards summer. Yet, the regulation of this seasonality remains unclear. We measured in situ monoterpene emissions from Scots pine shoots during several spring periods and analysed their dynamics in connection with the spring recovery of photosynthesis. We found high emission peaks caused by enhanced monoterpene synthesis consistently during every spring period (monoterpene emission bursts, MEB). The timing of the MEBs varied relatively little between the spring periods. The timing of the MEBs showed good agreement with the photosynthetic spring recovery, which was studied with simultaneous measurements of chlorophyll fluorescence, CO 2 exchange and a simple, temperature history‐based proxy for state of photosynthetic acclimation, S. We conclude that the MEBs were related to the early stages of photosynthetic recovery, when the efficiency of photosynthetic carbon reactions is still low whereas the light harvesting machinery actively absorbs light energy. This suggests that the MEBs may serve a protective functional role for the foliage during this critical transitory state and that these high emission peaks may contribute to atmospheric chemistry in the boreal forest in springtime. PMID:25850935

Onset of photosynthesis in spring speeds up monoterpene synthesis and leads to emission bursts.

PubMed

Aalto, J; Porcar-Castell, A; Atherton, J; Kolari, P; Pohja, T; Hari, P; Nikinmaa, E; Petäjä, T; Bäck, J

2015-11-01

Emissions of biogenic volatile organic compounds (BVOC) by boreal evergreen trees have strong seasonality, with low emission rates during photosynthetically inactive winter and increasing rates towards summer. Yet, the regulation of this seasonality remains unclear. We measured in situ monoterpene emissions from Scots pine shoots during several spring periods and analysed their dynamics in connection with the spring recovery of photosynthesis. We found high emission peaks caused by enhanced monoterpene synthesis consistently during every spring period (monoterpene emission bursts, MEB). The timing of the MEBs varied relatively little between the spring periods. The timing of the MEBs showed good agreement with the photosynthetic spring recovery, which was studied with simultaneous measurements of chlorophyll fluorescence, CO2 exchange and a simple, temperature history-based proxy for state of photosynthetic acclimation, S. We conclude that the MEBs were related to the early stages of photosynthetic recovery, when the efficiency of photosynthetic carbon reactions is still low whereas the light harvesting machinery actively absorbs light energy. This suggests that the MEBs may serve a protective functional role for the foliage during this critical transitory state and that these high emission peaks may contribute to atmospheric chemistry in the boreal forest in springtime. © 2015 John Wiley & Sons Ltd.

Chemical characteristics of ground-water discharge along the south rim of Grand Canyon in Grand Canyon National Park, Arizona, 2000-2001

USGS Publications Warehouse

Monroe, Stephen A.; Antweiler, Ronald C.; Hart, Robert J.; Taylor, Howard E.; Truini, Margot; Rihs, John R.; Felger, Tracey J.

2005-01-01

Springs flowing from the south rim of Grand Canyon are an important resource of Grand Canyon National Park, offering refuge to endemic and exotic terrestrial wildlife species and maintaining riparian areas. Population growth on the Coconino Plateau has increased the demand for additional development of ground-water resources, and such development could reduce spring discharge and affect the sustainability of riparian areas within the park. In addition, springs are an important source of drinking water for hikers and are culturally and economically important to Native Americans living in the region. Water samples were collected from May 2000 to September 2001 from 20 spring and creek sites that discharge water from the Redwall-Muav Limestone aquifer along the south rim of Grand Canyon. Sample collection sites were described and samples were analyzed for major ions, nutrients, trace elements, radioactivity, and selected isotopes, and potential sources of ground-water flow to the springs. Rock samples representing the major stratigraphic units of Grand Canyon were collected near the Bright Angel Fault and analyzed for mineralogy, strontium-87/strontium-86, and carbon-13/carbon-12. The chemical composition of water samples collected from a given spring did not vary appreciably over the course of the study. Although water at each spring had a temporally constant composition, the composition was chemically distinct from that of every other spring sampled, indicating spatial variability in the ground-water composition. Most samples had a calcium magnesium bicarbonate composition; a few had a substantial sulfate component. Concentrations of arsenic, nitrate, selenium, uranium, and gross alpha approached or exceeded U.S. Environmental Protection Agency Maximum Contaminant Levels in water discharging from some springs. Oxygen and hydrogen isotopic compositions varied little among samples, and for most sites the isotopic data plot close to the global meteoric water line or below the local meteoric water line. Isotopic enrichment indicates fractionation due to evaporation occurs at some sites. The evaporative process may occur prior to recharge or post-discharge. Flow paths are differentiated between the eastern part of the study area where strontium-87/strontium-86 values for water from springs and creeks are more radiogenic than strontium-87/strontium-86 values for water that discharges from sites farther west. Tritium and carbon isotope analyses indicate that residence time of ground-water discharge from springs and creeks ranges from less than 50 years to about 3,400 years. Water with a residence time of less than 50 years is absent at several sites. Discharge of most springs and creeks is a mixture of younger and older waters.

40 CFR 52.320 - Identification of plan.

Code of Federal Regulations, 2010 CFR

2010-07-01

....6 and introductory text of Section III.C.2.a of Regulation 1 adopted by the Colorado Air Quality... Fort Collins-Loveland, Colorado Springs, and Boulder-Denver Metropolitan Statistical Areas (MSA) as...

Energy management that generates terrain following versus apex-preserving hopping in man and machine.

PubMed

Kalveram, Karl Theodor; Haeufle, Daniel F B; Seyfarth, André; Grimmer, Sten

2012-01-01

While hopping, 12 subjects experienced a sudden step down of 5 or 10 cm. Results revealed that the hopping style was "terrain following". It means that the subjects pursued to keep the distance between maximum hopping height (apex) and ground profile constant. The spring-loaded inverse pendulum (SLIP) model, however, which is currently considered as template for stable legged locomotion would predict apex-preserving hopping, by which the absolute maximal hopping height is kept constant regardless of changes of the ground level. To get more insight into the physics of hopping, we outlined two concepts of energy management: "constant energy supply", by which in each bounce--regardless of perturbations--the same amount of mechanical energy is injected, and "lost energy supply", by which the mechanical energy that is going to be dissipated in the current cycle is assessed and replenished. When tested by simulations and on a robot testbed capable of hopping, constant energy supply generated stable and robust terrain following hopping, whereas lost energy supply led to something like apex-preserving hopping, which, however, lacks stability as well as robustness. Comparing simulated and machine hopping with human hopping suggests that constant energy supply has a good chance to be used by humans to generate hopping.

75 FR 21729 - Semiannual Regulatory Agenda, Spring 2010

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-26

...This agenda provides summary descriptions of significant and not significant regulations being developed in agencies of the U.S. Department of Agriculture (USDA) in conformance with Executive Order 12866 ``Regulatory Planning and Review.''

A mathematical description of a growing cell colony based on the mechanical bidomain model

NASA Astrophysics Data System (ADS)

Auddya, Debabrata; Roth, Bradley J.

2017-03-01

The mechanical bidomain model is used to describe a colony of cells growing on a substrate. Analytical expressions are derived for the intracellular and extracellular displacements. Mechanotransduction events are driven by the difference between the displacements in the two spaces, corresponding to the force acting on integrins. The equation for the displacement consists of two terms: one proportional to the radius that is the same in the intracellular and extracellular spaces (the monodomain term) and one that is proportional to a modified Bessel function that is responsible for mechanotransduction (the bidomain term). The model predicts that mechanotransduction occurs within a few length constants of the colony’s edge, and an expression for the length constant contains the intracellular and extracellular shear moduli and the spring constant of the integrins coupling the two spaces. The model predictions are qualitatively consistent with experiments on human embryonic stem cell colonies, in which differentiation is localized near the edge.

Dynamic flow modeling of riverine amphibian habitat with application to regulated flow management

Treesearch

S. Yarnell; A. Lind; J. Mount

2012-01-01

In regulated rivers, relicensing of hydropower projects can provide an opportunity to change flow regimes and reduce negative effects on sensitive aquatic biota. The volume of flow, timing and ramping rate of spring spills, and magnitude of aseasonal pulsed flows have potentially negative effects on the early life stages of amphibians, such as the Foothill yellow-...

Development of groundwater vulnerability zones in a data-scarce eogenetic karst area using Head-Guided Zonation and particle-tracking simulation methods.

PubMed

Klaas, Dua K S Y; Imteaz, Monzur Alam; Arulrajah, Arul

2017-10-01

Delineation of groundwater vulnerability zones based on a valid groundwater model is crucial towards an accurate design of management strategies. However, limited data often restrain the development of a robust groundwater model. This study presents a methodology to develop groundwater vulnerability zones in a data-scarce area. The Head-Guided Zonation (HGZ) method was applied on the recharge area of Oemau Spring in Rote Island, Indonesia, which is under potential risk of contamination from rapid land use changes. In this method the model domain is divided into zones of piecewise constant into which the values of subsurface properties are assigned in the parameterisation step. Using reverse particle-tracking simulation on the calibrated and validated groundwater model, the simulation results (travel time and pathline trajectory) were combined with the potential groundwater contamination risk from human activities (land use type and current practice) to develop three vulnerability zones. The corresponding preventive management strategies were proposed to protect the spring from contamination and to ensure provision of safe and good quality water from the spring. Copyright © 2017 Elsevier Ltd. All rights reserved.

Wide operation frequency band magnetostrictive vibration power generator using nonlinear spring constant by permanent magnet

NASA Astrophysics Data System (ADS)

Furumachi, S.; Ueno, T.

2016-04-01

We study magnetostrictive vibration based power generator using iron-gallium alloy (Galfenol). The generator is advantages over conventional, such as piezoelectric material in the point of high efficiency highly robust and low electrical impedance. Generally, the generator exhibits maximum power when its resonant frequency matches the frequency of ambient vibration. In other words, the mismatch of these frequencies results in significant decrease of the output. One solution is making the spring characteristics nonlinear using magnetic force, which distorts the resonant peak toward higher or lower frequency side. In this paper, vibrational generator consisting of Galfenol plate of 6 by 0.5 by 13 mm wound with coil and U shape-frame accompanied with plates and pair of permanent magnets was investigated. The experimental results show that lean of resonant peak appears attributed on the non-linear spring characteristics, and half bandwidth with magnets is 1.2 times larger than that without. It was also demonstrated that the addition of proof mass is effective to increase the sensitivity but also the bandwidth. The generator with generating power of sub mW order is useful for power source of wireless heath monitoring for bridge and factory machine.

Vibration characteristics and optimization for panel elastically supported in mobile phone

NASA Astrophysics Data System (ADS)

Kaito, Y.; Honda, S.; Narita, Y.

2016-09-01

In recent years, usage of smartphones and tablet terminals have spread around the world. These devices using touchscreen as a user interface are currently mainstream. Also, in order to let information of input or output surely know to users, there are some types of equipment having vibrational function in touchscreen. Here, the material of touchscreen consists of glass and the glass panel is fixed to a mobile phone's body by adhesive tapes along the edge of the panel. However, due to the difficulty of design of vibration, it needs investigation with a vast number of manufacturing prototypes. Moreover, the vibration characteristic of panels is not enough regarding intensity and a tactile impression. Therefore, in this study, the authors consider the vibration characteristic of glass panel elastically fixed by adhesive tapes along edges. First, they show modeling of adhesive tapes along edges of panel by using translational and rotational springs. Second, they show formulating vibration characteristic by using an energy method. Third, they optimize spring constants of translational and rotational springs by using Genetic Algorithm(GA) from the obtained expression. Finally, they consider natural frequencies and eigenmodes which were acquired from experiments and simulations.

Are Sierran Lakes Warming as a Result of Climate Change? The Effects of Climate Warming and Variation in Precipitation on Water Temperature in a Snowmelt-Dominated Lake

NASA Astrophysics Data System (ADS)

Sadro, S.; Melack, J. M.; Sickman, J. O.; Skeen, K.

2016-12-01

Water temperature regulates a broad range of fundamental ecosystem processes in lakes. While climate can be an important factor regulating lake temperatures, heterogeneity in the warming response of lakes is large, and variation in precipitation is rarely considered. We analyzed three decades of climate and water temperature data from a high-elevation catchment in the southern Sierra Nevada of California to illustrate the magnitude of warming taking place during different seasons and the role of precipitation in regulating lake temperatures. Significant climate warming trends were evident during all seasons except spring. Nighttime rates of climate warming were approximately 25% higher than daytime rates. Spatial patterns in warming were elevation dependent, with rates of temperature increase higher at sites above 2800 m.a.s.l. than below. Although interannual variation in snow deposition was high, the frequency and severity of recent droughts has contributed to a significant 3.4 mm year -1 decline in snow water equivalent over the last century. Snow accumulation, more than any other climate factor, regulated lake temperature; 94% of variation in summer lake temperature was regulated by precipitation as snow. For every 100 mm decrease in snow water equivalent there was a 0.62 ° increase in lake temperature. Drought years amplify warming in lakes by reducing the role of cold spring meltwaters in lake energy budgets and prolonging the ice-free period during which lakes warm. The combination of declining winter snowpack and warming air temperatures has the capacity to amplify the effect of climate warming on lake temperatures during drought years. Interactions among climatic factors need to be considered when evaluating ecosystem level effects, especially in mountain regions. For mountain lakes already affected by drought, continued climate warming during spring and autumn has the greatest potential to impact mean lake temperatures.

Vertical distribution of total carbon, nitrogen and phosphorus in sediments of Drug Spring Lake, Wudalianchi

NASA Astrophysics Data System (ADS)

Zeng, Ying; Yang, Chen

2018-02-01

The content of total organic carbon, total nitrogen and total phosphorus in sediments of Drug Spring Lake was detected and their vertical distribution characteristic was analysed. Results showed that there were significant changes to the content of total organic carbon, total nitrogen and total phosphorus in different depth of the columnar sediments. Their highest content both appeared in the interval of 10cm to 25cm corresponding to the period of 1980s to 1990s, when the tourism of Wudalianchi scenic area began to develop. It reflected the impact of human activities on the Drug Spring Lake. That means the regulation was still not enough, although a series of pollution control measures adopted by the government in recent years had initial success.

Instream flow assessment of streams draining the Arbuckle-Simpson Aquifer

USGS Publications Warehouse

Seilheimer, Titus S.; Fisher, William L.

2008-01-01

The availability of high quality water is critical to both humans and ecosystems. A recent proposal was made by rapidly expanding municipalities in central Oklahoma to begin transferring groundwater from the Arbuckle-Simpson aquifer, a sensitive sole-source aquifer in south-central Oklahoma. Concerned citizens and municipalities living on and getting their drinking water from the Arbuckle-Simpson lobbied the legislature to pass a temporary moratorium on groundwater transfer to allow for a comprehensive study of the aquifer and its ecosystems. We conducted an instream flow assessment using Physical Habitat Simulation (PHABSIM) on springs and streams with four spring-dependent species: two minnows, southern redbelly dace (Phoxinus erthyrogaster) and redspot chub (Nocomis asper); and two darters, least darter (Etheostoma microperca) and orangethroat darter (Etheostoma spectabile). Spring habitats are unique compared to other river habitats because they have constant flow and temperature, small and isolated habitat patches, and a general lack of predators. Our study sites included two spring-fed streams, one larger stream with high groundwater inputs, and a river with both groundwater and surface water inputs that is adjacent to the small spring-fed streams. These habitats meet the criteria for groundwater dependent ecosystems because they would not exist without the surface expression of groundwater. A total of 99 transects in all four sites were surveyed for channel elevation, and three sets of water surface elevation and water velocity were measured. Habitat suitability criteria were derived for the species at each site using nonparametric confidence limits based on underwater observations made by snorkelers. Simulations of flow were focused on declines in discharge, which is the expected effect of the proposed groundwater diversion. Our results show that only a small proportion of the total available area in each habitat is considered to be preferred habitat (Weighted Usable Area [WUA]) by the four target species. In the spring habitats, a maximum of 10% of the total area is preferred habitat and that dropped to as little as 3% with decreased flows. The quantity of WUA decreased when lower discharges were simulated for all the target species. Declines in the small amount of habitat that is already available would likely degrade these populations of fishes. In the larger river habitat, the highest WUA occurred at the lowest discharge, which leads us to conclude that in the event of dewatering of the spring habitats, the river should provide some refuge habitat for spring dependent species. Based on the findings of this study, groundwater removal from the aquifer near springs may have adverse impacts on fish habitat availability for spring dependent fish populations if seasonal trends in spring discharge are not maintained (higher in winter and lower in late summer). Quantifying the relationship of streamflow between gaged and ungaged springs in the Arbuckle-Simpson is a possible method to monitor and maintain flows in springs.

The influence of felling season and log-soaking temperature on the wetting and phenol formaldehyde adhesive bonding characteristics of birch veneer

Treesearch

Anti Rohumaa; Christopher G. Hunt; Charles R. Frihart; Pekka Saranpää; Martin Ohlmeyer; Mark Hughes

2014-01-01

Most adhesive studies employing wood veneer as the substrate assume that it is a relatively uniform material if wood species and veneer thickness are constant. In the present study, veneers from rotary cut birch (Betula pendula Roth) were produced from logs harvested in spring, autumn and winter, and soaked at 20°C and 70°C prior to peeling. Firstly...

Acquisition Review Quarterly. Vol. 2, No. 2, Spring 1995

DTIC Science & Technology

1995-01-01

alchemists , the people who tried to make gold for themselves and for the kings. They tried it until young science at the beginning of the age of the...the story of the alchemists and the inventors of the perpetual motion machine because of a rather astounding fact. Constant failures to achieve those...talking about the alchemists and the inventor of the perpetu-mobile. Applicable to the balanced budget, we may ask the impertinent ques- tion; if all

The Coast Guard Proceedings of the Marine Safety and Security Council. Volume 72, Number 1, Spring 2015

DTIC Science & Technology

2015-01-01

vapor-tight protection). This allows the team to make continuous entries into a contaminated area for at least 72 hours, before they need to restock...to secure a contamination source or to minimize human health or environmental impact. Tailored Response All NSF hazmat technicians are procient in...to identify unknown atmo- spheres and quantify contamination . The NSF also constantly evaluates new technology and advanced instru- ments that

Simultaneous detection of Hb constant spring (α142, TAA>CAA, α2) and the α2 IVS-I donor site (-TGAGG) deletion by a simple polymerase chain reaction-based method in Iran.

PubMed

Akhavan-Niaki, Haleh; Banihashemi, Ali; Mostafazadeh, Amrollah; Kholghi Oskooei, Vahid; Azizi, Mandana; Youssefi Kamangar, Reza; Elmi, Maryam Mitra

2012-01-01

Hb Constant Spring (Hb CS, codon 142, TAA>CAA, α2) (HBA2:c.427T>C) and α2 IVS-I donor site (GAGGTGAGG>GAGG - - - - -) (HBA2:c.95+2_95+6delTGAGG) are nondeletional α-thalassemia (α-thal) mutations found all over the world. Identification of α-thal genotypes in at-risk couples for severe anemia or in highly heterogeneous populations requires rapid, accurate and cost-effective genotyping methods. In this study, a pair of primers were used to specifically amplify an 883 bp fragment from the α2-globin gene in order to simultaneously identify these two mutations by a PCR-RFLP (polymerase chain reaction-restriction fragment length polymorphism) method. We determined the genotypic frequencies of Hb CS and the α2 IVS-I donor site mutations after amplification and enzymatic digestion with Tru9I in 238 northern Iranian samples referred for α-thal testing. Hb CS and the α2 IVS-I donor site mutations accounted for 21 (8.8%) and 29 (12.2%) of the nondeletional cases. This genotyping assay has proven to be a rapid, reliable and useful diagnostic tool for simultaneous detection of these two anomalies for genetic counseling or further prenatal diagnosis.

Comparison between capillary electrophoresis and high performance liquid chromatography for detection and quantification of Hb constant spring [Hb CS; α142, Term→Gln (TAA>CAA IN α2)].

PubMed

Waneesorn, Jarurin; Panyasai, Sitthichai; Kongthai, Kanyakan; Singboottra, Panthong; Pornprasert, Sakorn

2011-01-01

Hb Constant Spring [Hb CS; α142, Term→Gln (TAA>CAA in α2)] is often missed by routine laboratory testing since its mRNA as well as gene product are unstable and presented at a low level in peripheral blood. This study aimed to analyze the efficacy of capillary electrophoresis (CE) and high performance liquid chromatography (HPLC) for detecting and quantifying Hb CS in 19 heterozygotes and 14 homozygotes with Hb CS as well as 10 Hb H-CS disease subjects who were detected by molecular analysis. In the CE electrophoregram, Hb CS was seen at zone 2 and was observed in all samples, while the chromatogram of Hb CS peaks was found in 26.32% heterozygotes, 42.86% homozygotes and 90% Hb H-CS disease subjects, respectively. In addition, the Hb CS levels in each group of subjects quantified by CE were significantly higher than those quantified by HPLC. Based on the CE method, the lowest Hb CS level was found in the heterozygotes, whereas the highest level was found in the Hb H-CS disease patients. Therefore, the CE method was superior to the HPLC method for detecting Hb CS. Furthermore, the level of Hb CS quantified by CE proved useful in screening heterozygotes and homozygotes with Hb CS as well as Hb H-CS disease.

Changes over 50 years in fish fauna of a temperate coastal sea: Degradation of trophic structure and nursery function

NASA Astrophysics Data System (ADS)

van der Veer, Henk W.; Dapper, Rob; Henderson, Peter A.; Jung, A. Sarina; Philippart, Catharina J. M.; Witte, Johannes IJ.; Zuur, Alain F.

2015-03-01

The ongoing daily sampling programme of the fish fauna in the Dutch Wadden Sea using fixed gear was analysed for the years 1960-2011. Spring sampling caught immigrating fish from the coastal zone and autumn samples reflected emigration of young-of-the-year. In total 82 fish species were caught with no clear trend in biodiversity. In both spring and autumn total daily catch fluctuated and peaked in the late 1970s. From 1980 to the present catches of both pelagic and demersal species showed a 10-fold decrease in total biomass. Mean individual biomass decreased in spring between 1980 and the present from about 150 to 20 g wet weight. No trend was found in autumn mean individual biomass which fluctuated around 20 g wet weight. The trophic structure remained constant for both the demersal and benthopelagic fish fauna from 1980 to 2011, whilst the trophic position of pelagic fish in spring fell from about 3.9 to 3.1. Min/max auto-correlation factor analysis showed similar trends in spring and autumn species biomass time series: the first axis represented a decrease from the 1960s followed by stabilization from the mid-1990s. The second trend showed an increase with a maximum around 1980 followed by a steady decrease in spring and a decrease and stabilization from 2000 in autumn. It is argued that the most likely explanatory variables are a combination of external factors: increased water temperature, habitat destruction in the coastal zone (sand dredging and beach nourishment, fishing) and increased predation by top predators for the first trend, and large-scale hydrodynamic circulation for the second trend. We conclude that both the trophic structure of the coastal zone fauna and the nursery function of the Wadden Sea have been reduced since the 1980s. Our findings corroborate that ecological change in coastal ecosystems has not only occurred in the past but still continues.

Variation in spring migration routes and breeding distribution of northern pintails Anas acuta that winter in Japan

USGS Publications Warehouse

Hupp, Jerry W.; Yamaguchi, Noriyuki; Flint, Paul L.; Pearce, John M.; Tokita, Ken-ichi; Shimada, Tetsuo; Ramey, Andrew M.; Kharitonov, Sergei; Higuchi, Hiroyoshi

2011-01-01

In North America, spring migration routes and breeding distribution of northern pintails Anas acuta vary because some individuals opportunistically nest at mid-latitudes in years when ephemeral prairie wetlands are available, whereas others regularly nest in arctic and sub-arctic regions where wetland abundance is more constant. Less was known about migration routes and breeding distribution of pintails in East Asia. From 2007–2009 we marked 198 pintails on their wintering areas in Japan with satellite transmitters to: 1) document spring migration routes and summer distribution, 2) evaluate migratory connections and breeding season sympatry with North American pintails, and 3) determine if pintails used the same migration routes in fall as in spring. Most pintails (67%) migrated to the Kamchatka or Chukotka peninsulas in eastern Russia either directly from Japan or via Sakhalin Island, Russia. Remaining pintails primarily migrated to the Magadan region or Kolyma River Basin in eastern Russia via Sakhalin Island. The Chukotka Peninsula was the most common summer destination, with highest densities in the Anadyr Lowlands; a region also used by pintails that migrate from North America. One pintail migrated to St. Lawrence Island, Alaska, in spring and another briefly migrated to the western coast of Alaska in fall. Autumn migration routes generally mirrored spring migration although most pintails bypassed Sakhalin Island in fall. Compared to North American pintails, pintails that winter in Japan exhibited less variation in migration routes and breeding distribution, and nested at higher latitudes. In the Russian Far East there is no region with habitats comparable in extent to the ephemeral mid-latitude wetlands of North America. Consequently, East Asian pintails mainly nest in arctic and sub-arctic regions where annual consistency in wetlands promotes constancy in migration routes and breeding distribution. Breeding season sympatry between pintails from different continents results more from North American pintails migrating to eastern Russia than from Japanese pintails migrating to North America.

[Frequencies of airborne moulds in Zagreb].

PubMed

Segvić, Maja; Pepeljnjak, Stjepan

2004-06-01

Airborne fungi are sometimes associated with several respiratory diseases and allergies. This paper describes a study of qualitative and quantitative variations in the occurrence of airborne moulds in Zagreb area on three locations: centre of the city (C), Pharmaceutical Botanical Garden "Fran Kusan" (BG) and the mountain Medvednica (M) during autumn, winter, spring and summer 2002-03. Lower concentrations of airborne moulds were found in all three locations in autumn (up to 76.88 CFU/m3) and winter (31.46 CFU/m3), with significantly higher levels in C and BG than in M (P<0.001). In spring and summer, these concentrations were much higher in all sampling sites and were significantly higher in C (160.00 CFU/m3) and BG (134.00 CFU/m3) in spring than in M (90.07 CFU/m3) (P<0.001). In summer, significantly higher concentration was found in C (237.5 CFU/m3) than in BG (186.50 CFU/m3) (P<0.01), while concentrations in C and M (216.70 CFU/m3) were similar. Airspora belonging to 29 fungal genera were identified, and allergologicaly significant moulds, Cladosporium (up to 79.5%) and Alternaria (up to 59.4%) dominated in all sampling sites. Penicillium, Fusarium and Aspergillus were also constant fungal entities (43.0-70.5%), but in much lower concentrations than Cladosporium and Alternaria. Airsporas of Cladosporium and Alternaria were more frequent in spring and summer in all locations, with significantly higher concentrations in C and BG (P<0.05). The risk from allergies increases with higher airspora concentrations in spring and summer due to an increase in Cladosporium and Alternaria.

Participation in the Mars Data Analysis Program: Analysis of cloud forms in Viking and Mariner 9 images

NASA Technical Reports Server (NTRS)

Gierasch, P.; Kahn, R. A.

1985-01-01

The first systematic account of the climate of Mars, based upon observations was produced. Cloud data were used to determine spatially and temporally varying near-surface wind direction, relative wind speed, static stability, and humidity conditions on a global scale. Existing models of meteorological processes were critically reexamined in light of the data, and more stringent constraints were set on global processes. Several discoveries were made, including the large extent and seasonal variability of the Mars equatorial Hadley cell, the failure of high latitude winds to reverse direction in early northern spring, the change in meridional wind component in southern midautum, and the almost constant cloud cover in the northern hemisphere, during spring and summer primarily by condensate clouds and in fall and winter by condensates and dust. The implications of these observations are discussed.

Hydrodynamic impact of a system with a single elastic mode I : theory and generalized solution with an application to an elastic airframe

NASA Technical Reports Server (NTRS)

Mayo, Wilbur L

1952-01-01

Solutions of impact of a rigid prismatic float connected by a massless spring to a rigid upper mass are presented. The solutions are based on hydrodynamic theory which has been experimentally confirmed for a rigid structure. Equations are given for defining the spring constant and the ratio of the sprung mass to the lower mass so that the two-mass system provides representation of the fundamental mode of an airplane wing. The forces calculated are more accurate than the forces which would be predicted for a rigid airframe since the effect of the fundamental mode on the hydrodynamic force is taken into account. In a comparison of the theoretical data with data for a severe flight-test landing impact, the effect of the fundamental mode on the hydrodynamic force is considered and response data are compared with experimental data.

Analysis and experimental evaluation of a Stewart platform-based force/torque sensor

NASA Technical Reports Server (NTRS)

Nguyen, Charles C.; Antrazi, Sami S.

1992-01-01

The kinematic analysis and experimentation of a force/torque sensor whose design is based on the mechanism of the Stewart Platform are discussed. Besides being used for measurement of forces/torques, the sensor also serves as a compliant platform which provides passive compliance during a robotic assembly task. It consists of two platforms, the upper compliant platform (UCP) and the lower compliant platform (LCP), coupled together through six spring-loaded pistons whose length variations are measured by six linear voltage differential transformers (LVDT) mounted along the pistons. Solutions to the forward and inverse kinematics of the force sensor are derived. Based on the known spring constant and the piston length changes, forces/torques applied to the LCP gripper are computed using vector algebra. Results of experiments conducted to evaluate the sensing capability of the force sensor are reported and discussed.

Users manual: Dynamics of two bodies connected by an elastic tether, six degrees of freedom forebody and five degrees of freedom decelerator

NASA Technical Reports Server (NTRS)

Doyle, G. R., Jr.; Burbick, J. W.

1974-01-01

The equations of motion and a computer program for the dynamics of a six degree of freedom body joined to a five degree of freedom body by a quasilinear elastic tether are presented. The forebody is assumed to be a completely general rigid body with six degrees of freedom; the decelerator is also assumed to be rigid, but with only five degrees of freedom (symmetric about its longitudinal axis). The tether is represented by a spring and dashpot in parallel, where the spring constant is a function of tether elongation. Lagrange's equation is used to derive the equations of motion with the Lagrange multiplier technique used to express the constraint provided by the tether. A computer program is included which provides a time history of the dynamics of both bodies and the tension in the tether.

Information Control: Preventing a Vietnamese Spring?

DTIC Science & Technology

2013-11-01

challenges with labor market tensions and land management corruption continue to plague the Party and demonstrate their inability to effectively...the 1997 regulation in 2001. The 2001 regulation provided for a “partial liberalisation of the internet market ” while placing a “more stringent...Vietnam increased. This increase resulted in market competition and lower prices for internet service, broadening the availability of the internet to

Riparian Cottonwood Ecosystems and Regulated Flows in Kootenai and Yakima Sub-Basins : Volume II Yakima (Overview, Report, Appendices).

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

Jamieson, Bob; Braatne, Jeffrey H.

Riparian vegetation and especially cottonwood and willow plant communities are dependent on normative flows and especially, spring freshette, to provide conditions for recruitment. These plant communities therefore share much in common with a range of fish species that require natural flow conditions to stimulate reproduction. We applied tools and techniques developed in other areas to assess riparian vegetation in two very different sub-basins within the Columbia Basin. Our objectives were to: Document the historic impact of human activity on alluvial floodplain areas in both sub-basins; Provide an analysis of the impacts of flow regulation on riparian vegetation in two systemsmore » with very different flow regulation systems; Demonstrate that altered spring flows will, in fact, result in recruitment to cottonwood stands, given other land uses impacts on each river and the limitations imposed by other flow requirements; and Assess the applicability of remote sensing tools for documenting the distribution and health of cottonwood stands and riparian vegetation that can be used in other sub-basins.« less

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

Jones, B.; Renaut, R.W.

Complex calcite crystals are an integral component of precipitates that form around the orifices of the Loburu and Mawe Moto hot springs on the shores of Lake bogoria, Kenya. Two types of large (up to 4 cm long) noncrystallographic dendrites are important components of these deposits. Feather dendrites are characterized by multiple levels of branching with individual branches developed through crystal splitting and spherulitic growth. Scandulitic (from Latin meaning shingle) dendrites are formed of stacked calcite crystals and are generally more compact than feather dendrites. These developed through the incremental stacking of rectangular-shaped calcite crystals that initially grew as skeletalmore » crystals. Feather and scandulitic dendrites precipitated from the same waters in the same springs. The difference in morphology is therefore related to microenvironments in which they grew. Feather dendrites grew in any direction in pools of free-standing water provided that they were in constant contact with the solute. Conversely, scandulitic dendrites grew on rims of dams where water flowed over the surface in concert with the pulses of spring water. Thus, each calcite crystal in these dendrites represents one episode of crystal growth. The orientation of the component crystals in scandulitic dendrites is controlled by the topography of the dam or surface, not crystallographic criteria. The noncrystallographic dendrites formed from spring waters with initial temperatures of 90--99 C. Surficial water cooling, loss of CO{sub 2}, and presence of other elements that can interfere with crystal growth contributed to the formation of these unusual crystals.« less

MEMS squeezer for the measurement of single cell rupture force, stiffness change, and hysteresis

NASA Astrophysics Data System (ADS)

Barazani, B.; Warnat, S.; Fine, A.; Hubbard, T.

2017-02-01

A MEMS squeezer able to compress single living cells underwater until rupture was designed and tested. The relatively large motion range of the device in aqueous media (~2.5 µm) allows provoking cell disruption while measuring cell mechanical properties before and after membrane rupture. An AC driven electrothermal micro actuator with mechanical amplification pressed single cells against a reference back spring. Deformations of the cell and the reference spring were measured with nanoscale resolution using optical Fourier transform techniques. The motion of the reference spring divided by the cell deformation provides the cell stiffness relative to the reference spring constant. An abrupt change in the cell stiffness and the appearance of cracks indicated the cell wall rupture force was reached. A total of 22 baker’s yeast cells (Saccharomyces cerevisiae) were squeezed with the micro device. The average force necessary to rupture the cell membrane was 0.47  ±  0.1 µN. Before rupture the cells had an average stiffness of 9.3  ±  3.1 N m-1 the post-rupture stiffness dropped to 0.94  ±  0.57 N m-1. Cell hysteresis was also measured: cells squeezed and released before reaching the rupture force showed residual deformations below 100 nm, while cells squeezed past the rupture force and then released showed residual deformations between 490 and 990 nm.

A positive relationship between spring temperature and productivity in 20 songbird species in the boreal zone.

PubMed

Meller, Kalle; Piha, Markus; Vähätalo, Anssi V; Lehikoinen, Aleksi

2018-03-01

Anthropogenic climate warming has already affected the population dynamics of numerous species and is predicted to do so also in the future. To predict the effects of climate change, it is important to know whether productivity is linked to temperature, and whether species' traits affect responses to climate change. To address these objectives, we analysed monitoring data from the Finnish constant effort site ringing scheme collected in 1987-2013 for 20 common songbird species together with climatic data. Warm spring temperature had a positive linear relationship with productivity across the community of 20 species independent of species' traits (realized thermal niche or migration behaviour), suggesting that even the warmest spring temperatures remained below the thermal optimum for reproduction, possibly due to our boreal study area being closer to the cold edge of all study species' distributions. The result also suggests a lack of mismatch between the timing of breeding and peak availability of invertebrate food of the study species. Productivity was positively related to annual growth rates in long-distance migrants, but not in short-distance migrants. Across the 27-year study period, temporal trends in productivity were mostly absent. The population sizes of species with colder thermal niches had decreasing trends, which were not related to temperature responses or temporal trends in productivity. The positive connection between spring temperature and productivity suggests that climate warming has potential to increase the productivity in bird species in the boreal zone, at least in the short term.

Finite element analysis of stress transfer mechanism from matrix to the fiber in SWCN reinforced nanocomposites

NASA Astrophysics Data System (ADS)

Günay, E.

2017-02-01

This study defined as micromechanical finite element (FE) approach examining the stress transfer mechanism in single-walled carbon nanotube (SWCN) reinforced composites. In the modeling, 3D unit-cell method was evaluated. Carbon nanotube reinforced composites were modeled as three layers which comprises CNT, interface and matrix material. Firstly; matrix, fiber and interfacial materials all together considered as three layered cylindrical nanocomposite. Secondly, the cylindrical matrix material was assumed to be isotropic and also considered as a continuous medium. Then, fiber material was represented with zigzag type SWCNs. Finally, SWCN was combined with the elastic medium by using springs with different constants. In the FE modeling of SWCN reinforced composite model springs were modeled by using ANSYS spring damper element COMBIN14. The developed interfacial van der Waals interaction effects between the continuous matrix layer and the carbon nanotube fiber layer were simulated by applying these various spring stiffness values. In this study, the layered composite cylindrical FE model was presented as the equivalent mechanical properties of SWCN structures in terms of Young's modulus. The obtained results and literature values were presented and discussed. Figures, 16, 17, and 18 of the original article PDF file, as supplied to AIP Publishing, were affected by a PDF-processing error. Consequently, a solid diamond symbol appeared instead of a Greek tau on the y axis labels for these three figures. This article was updated on 17 March 2017 to correct the PDF-processing error, with the scientific content remaining unchanged.

ANISOTROPY DETERMINATIONS IN EXCHANGE SPRING MAGNETS.

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

LEWIS,L.H.; HARLAND,C.L.

2002-08-18

Ferromagnetic nanocomposites, or ''exchange spring'' magnets, possess a nanoscaled microstructure that allows intergrain magnetic exchange forces to couple the constituent grains and alter the system's effective magnetic anisotropies. While the effects of the anisotropy alterations are clearly seen in macroscopic magnetic measurement, it is extremely difficult to determine the detailed effects of the system's exchange coupling, such as the interphase exchange length, the inherent domain wall widths or the effective anisotropies of the system. Clarification of these materials parameters may be obtained from the ''micromagnetic'' phenomenological model, where the assumption of magnetic reversal initiating in the magnetically-soft regions of themore » exchange-spring maqet is explicitly included. This approach differs from that typically applied by other researchers and allows a quantitative estimate of the effective anisotropies of an exchange spring system. Hysteresis loops measured on well-characterized nanocomposite alloys based on the composition Nd{sub 2}Fe{sub 14}B + {alpha}-Fe at temperatures above the spin reorientation temperature were analyzed within the framework of the micromagnetic phenomenological model. Preliminary results indicate that the effective anisotropy constant in the material is intermediate to that of bulk {alpha}-Fe and bulk Nd{sub 2}Fe{sub 14}B and increases with decreasing temperature. These results strongly support the idea that magnetic reversal in nanocomposite systems initiates in the lower-anisotropy regions of the system, and that the soft-phase regions become exchange-hardened by virtue of their proximity to the magnetically-hard regions.« less

Estimates of annual survival probabilities for adult Florida manatees (Trichechus manatus latirostris)

USGS Publications Warehouse

Langtimm, C.A.; O'Shea, T.J.; Pradel, R.; Beck, C.A.

1998-01-01

The population dynamics of large, long-lived mammals are particularly sensitive to changes in adult survival. Understanding factors affecting survival patterns is therefore critical for developing and testing theories of population dynamics and for developing management strategies aimed at preventing declines or extinction in such taxa. Few studies have used modern analytical approaches for analyzing variation and testing hypotheses about survival probabilities in large mammals. This paper reports a detailed analysis of annual adult survival in the Florida manatee (Trichechus manatus latirostris), an endangered marine mammal, based on a mark-recapture approach. Natural and boat-inflicted scars distinctively 'marked' individual manatees that were cataloged in a computer-based photographic system. Photo-documented resightings provided 'recaptures.' Using open population models, annual adult-survival probabilities were estimated for manatees observed in winter in three areas of Florida: Blue Spring, Crystal River, and the Atlantic coast. After using goodness-of-fit tests in Program RELEASE to search for violations of the assumptions of mark-recapture analysis, survival and sighting probabilities were modeled under several different biological hypotheses with Program SURGE. Estimates of mean annual probability of sighting varied from 0.948 for Blue Spring to 0.737 for Crystal River and 0.507 for the Atlantic coast. At Crystal River and Blue Spring, annual survival probabilities were best estimated as constant over the study period at 0.96 (95% CI = 0.951-0.975 and 0.900-0.985, respectively). On the Atlantic coast, where manatees are impacted more by human activities, annual survival probabilities had a significantly lower mean estimate of 0.91 (95% CI = 0.887-0.926) and varied unpredictably over the study period. For each study area, survival did not differ between sexes and was independent of relative adult age. The high constant adult-survival probabilities estimated for manatees in the Blue Spring and Crystal River areas were consistent with current mammalian life history theory and other empirical data available for large, long-lived mammals. Adult survival probabilities in these areas appeared high enough to maintain growing populations if other traits such as reproductive rates and juvenile survival were also sufficiently high lower and variable survival rates on the Atlantic coast are cause for concern.

Recurrence and interoccurrence behavior of self-organized complex phenomena

NASA Astrophysics Data System (ADS)

Abaimov, S. G.; Turcotte, D. L.; Shcherbakov, R.; Rundle, J. B.

2007-08-01

The sandpile, forest-fire and slider-block models are said to exhibit self-organized criticality. Associated natural phenomena include landslides, wildfires, and earthquakes. In all cases the frequency-size distributions are well approximated by power laws (fractals). Another important aspect of both the models and natural phenomena is the statistics of interval times. These statistics are particularly important for earthquakes. For earthquakes it is important to make a distinction between interoccurrence and recurrence times. Interoccurrence times are the interval times between earthquakes on all faults in a region whereas recurrence times are interval times between earthquakes on a single fault or fault segment. In many, but not all cases, interoccurrence time statistics are exponential (Poissonian) and the events occur randomly. However, the distribution of recurrence times are often Weibull to a good approximation. In this paper we study the interval statistics of slip events using a slider-block model. The behavior of this model is sensitive to the stiffness α of the system, α=kC/kL where kC is the spring constant of the connector springs and kL is the spring constant of the loader plate springs. For a soft system (small α) there are no system-wide events and interoccurrence time statistics of the larger events are Poissonian. For a stiff system (large α), system-wide events dominate the energy dissipation and the statistics of the recurrence times between these system-wide events satisfy the Weibull distribution to a good approximation. We argue that this applicability of the Weibull distribution is due to the power-law (scale invariant) behavior of the hazard function, i.e. the probability that the next event will occur at a time t0 after the last event has a power-law dependence on t0. The Weibull distribution is the only distribution that has a scale invariant hazard function. We further show that the onset of system-wide events is a well defined critical point. We find that the number of system-wide events NSWE satisfies the scaling relation NSWE ∝(α-αC)δ where αC is the critical value of the stiffness. The system-wide events represent a new phase for the slider-block system.

North Dakota Floods

NASA Image and Video Library

2009-04-19

The Spring, 2009 floods along the Red River between North Dakota and Minnesota affected cities in the two states, especially Fargo and Whitehead. NASA Terra spacecraft acquired this image on April 9, 2009. This image shows the flood waters north of the towns spilling over into farmlands. Residents were on constant flood alert, filling sandbags, and hoping that the water level would finally recede. Standing water appears in shades of dark green and brown, wet ground is dark grey, and snow is white. http://photojournal.jpl.nasa.gov/catalog/PIA11989

Cyber-Physical Systems to Understand the Dynamics of Nonlinear Aeroelastic Systems for Flexible MAVs and Energy Harvesting Applications

DTIC Science & Technology

2015-09-28

release. Rotary encoder Brushless servo motor Wind tunnel bottom wall Stainless steel shaft Shaft coupling Wind tunnel top wall Titanium flat plate...illustrating the flat plate mounted to a virtual spring-damper system in the wind tunnel test section. 2 DISTRIBUTION A: Distribution approved for...non-dimensional ratios. For example the non-dimensional stiffness, k∗ = 2k/(ρU2∞c 2h), can be kept constant even if the wind speed, U∞, chord, c, and

NMC stratospheric analyses during the 1987 Antarctic expedition

NASA Technical Reports Server (NTRS)

Gelman, Melvyn E.; Newman, Paul A.

1988-01-01

Stratospheric constant pressure analyses of geopotential height and temperature, produced as part of regular operations at the National Meteorological Center (NMC), were used by several participants of the Antarctic Ozone Expedition. A brief decription is given of the NMC stratospheric analyses and the data that are used to derive them. In addition, comparisons of the analysis values at the locations of radiosonde and aircraft data are presented to provide indications for assessing the representativeness of the NMC stratospheric analyses during the 1987 Antarctic winter-spring period.

Unaccounted source of systematic errors in measurements of the Newtonian gravitational constant G

NASA Astrophysics Data System (ADS)

DeSalvo, Riccardo

2015-06-01

Many precision measurements of G have produced a spread of results incompatible with measurement errors. Clearly an unknown source of systematic errors is at work. It is proposed here that most of the discrepancies derive from subtle deviations from Hooke's law, caused by avalanches of entangled dislocations. The idea is supported by deviations from linearity reported by experimenters measuring G, similarly to what is observed, on a larger scale, in low-frequency spring oscillators. Some mitigating experimental apparatus modifications are suggested.

Proceedings of the Annual Meeting, Aquatic Plant Control Research Program (25th) Held in Orlando, Florida on 26-30 November 1990

DTIC Science & Technology

1991-06-01

to locate and treat pioneering aquatic plants in late spring to assist in populations prior to their rapid expansion the formulation of treatment... Demography Wulff, R. D. 1986a. "Seed Size Variation in and Its Consequences for Potamogeton Desmodium paniculatum; I. Factors Af- pectinatus L...formed by the confluence of the include longevity of the method, constant fish- Wateree and Congaree Rivers. The Wateree feeding activity against

Finger-Circumference-Measuring Device

NASA Technical Reports Server (NTRS)

Le, Suy

1995-01-01

Easy-to-use device quickly measures circumference of finger (including thumb) on human hand. Includes polytetrafluoroethylene band 1/8 in. wide, bent into loop and attached to tab that slides on scale graduated in millimeters. Sliding tab preloaded with constant-force tension spring, which pulls tab toward closure of loop. Designed to facilitate measurements at various points along fingers to obtain data for studies of volumetric changes of fingers in microgravity. Also used in normal Earth gravity studies of growth and in assessment of diseases like arthritis.

Current Regulator For Sodium-Vapor Lamps

NASA Technical Reports Server (NTRS)

Mclyman, W. T.

1989-01-01

Regulating circuit maintains nearly-constant alternating current in sodium-vapor lamp. Regulator part of dc-to-ac inverter circuit used to supply power to street lamp from battery charged by solar-cell array.

Regulator for intravenous feeding

NASA Technical Reports Server (NTRS)

Dimeff, J.

1975-01-01

Float valve maintains constant level of solution, providing constant drop rate as long as solution can flow into patient's vein. Second float valve allows solution to enter vein, but prevents entry of air.

The beneficial effect of the sap of Acer mono in an animal with low-calcium diet-induced osteoporosis-like symptoms.

PubMed

Lee, Geun-Shik; Byun, Hyuk-Soo; Kim, Man-Hee; Lee, Bo-Mi; Ko, Sang-Hwan; Jung, Eui-Man; Gwak, Ki-Seob; Choi, In-Gyu; Kang, Ha-Young; Jo, Hyun-Jin; Lee, Hak-Ju; Jeung, Eui-Bae

2008-11-01

The sap of Acer mono has been called 'bone-benefit-water' in Korea because of its mineral and sugar content. In particular, the calcium concentration of the sap of A. mono is 37.5 times higher than commercial spring water. In the current study, we examined whether A. mono sap could improve or prevent osteoporosis-like symptoms in a mouse model. Male mice (3 weeks old) were fed a low-calcium diet supplemented with 25, 50 or 100 % A. mono sap, commercial spring water or a high calcium-containing solution as a beverage for 7 weeks. There were no differences in weekly weight gain and food intake among all the groups. Mice that were given a low-calcium diet supplemented with commercial spring water developed osteoporosis-like symptoms. To assess the effect of sap on osteoporosis-like symptoms, we examined serum calcium concentration, and femur density and length, and carried out a histological examination. Serum calcium levels were significantly lower in mice that received a low-calcium diet supplemented with commercial spring water (the negative control group), and in the 25 % sap group compared to mice fed a normal diet, but were normal in the 50 and 100 % sap and high-calcium solution groups. Femur density and length were significantly reduced in the negative control and 25 % sap groups. These results indicate that a 50 % sap solution can mitigate osteoporosis-like symptoms induced by a low-calcium diet. We also examined the regulation of expression of calcium-processing genes in the duodenum and kidney. Duodenal TRPV6 and renal calbindin-D9k were up-regulated dose-dependently by sap, and the levels of these factors were higher than those attained in the spring water-treated control. The results demonstrate that the sap of A. mono ameliorates the low bone density induced by a low-calcium diet, most likely by increasing calcium ion absorption.

[Features of seasonal reorganizations of the central mechanisms of regulation in children northerners with different level of social risk].

PubMed

Soroko, S I; Rozhkov, V P; Bekshaev, S S

2013-12-01

The paper presents a comparative analysis of frequency, spatial-temporal parameters and three-dimensional localization of EEG sources that characterize changes of cortical-subcortical interactions processes in autumn and spring periods at northern schoolchildren living in satisfactory and disadvantaged (risk group) conditions of the social (family) environment. Seasonal rearrangement of interaction between wave components of main EEG rhythms was revealed. School students present regressive changes in the EEG pattern temporal organization in spring compared to autumn, and this effect was more expressed at adolescents from group of risk. Data EEDS-tomography showed increased activity in the prefrontal, cingular and subcallosal areas of the cortex in the autumn period that could be related to the mechanisms of season depression caused by the significant reduction of the day length in the North. The increased activity of the limbic system structures which is persisted in the spring in adolescents from risk group narrows the range of regulation of adaptive reactions. Unfavorable conditions of the family environment are an additional stress factor to increased load on the regulatory mechanisms that have a negative impact on the emotional-motivation behavior of children and adolescents, thus increasing the risk of the school and of social disadaptation.

Constant voltage electro-slag remelting control

DOEpatents

Schlienger, Max E.

1996-01-01

A system for controlling electrode gap in an electro-slag remelt furnace has a constant regulated voltage and an eletrode which is fed into the slag pool at a constant rate. The impedance of the circuit through the slag pool is directly proportional to the gap distance. Because of the constant voltage, the system current changes are inversely proportional to changes in gap. This negative feedback causes the gap to remain stable.

Exploring the Role of Peer Advice in Self-Regulated Learning: Metacognitive, Social, and Environmental Factors.

PubMed

Rashid, Hanin; Lebeau, Robert; Saks, Norma; Cianciolo, Anna T; Artino, Anthony R; Shea, Judy A; Ten Cate, Olle

2016-01-01

This Conversation Starters article presents a selected research abstract from the 2016 Association of American Medical Colleges Northeast Region Group on Educational Affairs annual spring meeting. The abstract is paired with the integrative commentary of three experts who shared their thoughts stimulated by the pilot study. These thoughts explore the metacognitive, social, and environmental mechanisms whereby advice plays a role in self-regulated learning.

[Kinetic study of neutrophil and macrophage cell reproduction and differentiation in the common frog at different seasons of the year].

PubMed

Goryshina, E N

1980-07-01

A supposed life-span of hemosiderin-containing macrophages in the frog spleen has been described on the basis of their morphology, changes in the number of nuclei, and results of autoradiographic studies of DNA synthesis in various seasons. The hibernating stages of the lines are hemocytoblasts, mononuclear and moderately polynuclear macrophages, which renew the phagocytosis and nuclear division at the beginning of spring. A new population of monomuclear macrophages develops from hemocytoblasts during spring. Large polynuclear forms appear during spring and summer, reach their maximal size and erythrophagocytotic activity towards the end of summer, and die in winter. The most part of the stored pigments is removed from the spleen. DNA synthesis and division occur asynchronously in the nuclei of one cell. Some pathologic forms of macrophages are described. The similarity in the proliferation cell kinetics of neutrophilic and macrophagal lines confirms a close relation between the two. The role of temperature and photoperiod in the regulations of proliferative activity of these cells during spring is discussed.

The photochemical reflectance index provides an optical indicator of spring photosynthetic activation in evergreen conifers.

PubMed

Wong, Christopher Y S; Gamon, John A

2015-04-01

In evergreens, the seasonal down-regulation and reactivation of photosynthesis is largely invisible and difficult to assess with remote sensing. This invisible phenology may be changing as a result of climate change. To better understand the mechanism and timing of these hidden physiological transitions, we explored several assays and optical indicators of spring photosynthetic activation in conifers exposed to a boreal climate. The photochemical reflectance index (PRI), chlorophyll fluorescence, and leaf pigments for evergreen conifer seedlings were monitored over 1 yr of a boreal climate with the addition of gas exchange during the spring. PRI, electron transport rate, pigment levels, light-use efficiency and photosynthesis all exhibited striking seasonal changes, with varying kinetics and strengths of correlation, which were used to evaluate the mechanisms and timing of spring activation. PRI and pigment pools were closely timed with photosynthetic reactivation measured by gas exchange. The PRI provided a clear optical indicator of spring photosynthetic activation that was detectable at leaf and stand scales in conifers. We propose that PRI might provide a useful metric of effective growing season length amenable to remote sensing and could improve remote-sensing-driven models of carbon uptake in evergreen ecosystems. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

Temperature and frequency dependence of anelasticity in a nickel oscillator

NASA Astrophysics Data System (ADS)

Berg, Robert F.

1995-09-01

The frequency dependence of the real and imaginary parts of a nickel oscillator's transfer function is described over 3 decades in frequency by the use of simple expressions. These expressions incorporate only the resonance frequency ω0, the quality factor Q, and a characteristic exponent β determined by a single measurement of creep. They are based on the ansatz φ(ω)=Q-1(ω/ω0)-β, where φ is the imaginary part of the spring constant. Over a 100 K range of temperature T, the exponent β≂0.18 was constant even though Q(T) changed by a factor of 8. These expressions are potentially useful for accurately describing a mechanical oscillator whose transfer function must be modeled at frequencies far below ω0. Examples include accelerometers based on a flexure element and suspensions for interferometric gravitational wave detectors.

Design, Analysis and Implementation of an Experimental System to Harvest Energy From Atmospheric Temperature Variations Using Ethyl Chloride Filled Bellows

NASA Astrophysics Data System (ADS)

Ali, Gibran

The increase in global warming and the dwindling supplies of fossil fuels have shifted the focus from traditional to alternate sources of energy. This has resulted in a concerted effort towards finding new energy sources as well as better understanding traditional renewable energy sources such as wind and solar power. In addition to the shift in focus towards alternate energy, the last two decades have offered a dramatic rise in the use of digital technologies such as wireless sensor networks that require small but isolated power supplies. Energy harvesting, a method to gather energy from ambient sources including sunlight, vibrations, heat, etc., has provided some success in powering these systems. One of the unexplored areas of energy harvesting is the use of atmospheric temperature variations to obtain usable energy. This thesis investigates an innovative mechanism to extract energy from atmospheric variations using ethyl chloride filled mechanical bellows. The energy harvesting process was divided into two parts. The first part consisted of extracting energy from the temperature variations and converting it into the potential energy stored in a linear coil spring. This was achieved by designing and fabricating an apparatus that consisted of an ethyl chloride filled bellows working against a mechanical spring in a closed and controlled environment. The bellows expanded/contracted depending upon the ambient temperature and the energy harvested was calculated as a function of the bellows' length. The experiments showed that 6 J of potential energy may be harvested for a 23°C change in temperature. The numerical results closely correlated to the experimental data with an error magnitude of 1%. In regions with high diurnal temperature variation, such an apparatus may yield approximately 250 microwatts depending on the diurnal temperature range. The second part of the energy harvesting process consisted of transforming linear expansion of the bellows into electric power. A system was designed and simulated using Mathworks Simulink and SimDriveline packages that converted the linear oscillations of the bellows into electric power. This was achieved in two steps; a gear train was designed that would convert the linear displacement of the bellows into potential energy stored in a spiral spring. The spiral spring would then periodically engage to a small generator producing electric power. The electrical power generated was found to depend solely on the potential energy stored in the spring. It was discovered that for a sinusoidal force with constant amplitude and frequency, the potential energy stored in the spring depended on the duration of force input and the parameters of the drivetrain such as the spring stiffness, the gear ratios, and the pinion radii. After simulating the system for different parameters, an optimal set of values was presented to maximize the electrical energy output for a given duration of time. For constant amplitude (120 N) sinusoidal force input with a time period of T seconds, the system stored 37 J, 65 J, and 90 J after a time of 3T, 5T, and 7T, respectively. The electric power output was 7.14 microwatts for a conversion efficiency of 5%. The next step is building a physical geartrain generator assembly based on the design presented in the thesis. The physical system will first be verified by simulating the force input using a pneumatic cylinder. The two parts of the research experiment can then be integrated into one system that would generate electric power directly from temporal temperature and pressure variations.

Classification of Thermal Patterns at Karst Springs and Cave Streams

USGS Publications Warehouse

Luhmann, A.J.; Covington, M.D.; Peters, Albert J.; Alexander, S.C.; Anger, C.T.; Green, J.A.; Runkel, Anthony C.; Alexander, E.C.

2011-01-01

Thermal patterns of karst springs and cave streams provide potentially useful information concerning aquifer geometry and recharge. Temperature monitoring at 25 springs and cave streams in southeastern Minnesota has shown four distinct thermal patterns. These patterns can be divided into two types: those produced by flow paths with ineffective heat exchange, such as conduits, and those produced by flow paths with effective heat exchange, such as small fractures and pore space. Thermally ineffective patterns result when water flows through the aquifer before it can equilibrate to the rock temperature. Thermally ineffective patterns can be either event-scale, as produced by rainfall or snowmelt events, or seasonal scale, as produced by input from a perennial surface stream. Thermally effective patterns result when water equilibrates to rock temperature, and the patterns displayed depend on whether the aquifer temperature is changing over time. Shallow aquifers with seasonally varying temperatures display a phase-shifted seasonal signal, whereas deeper aquifers with constant temperatures display a stable temperature pattern. An individual aquifer may display more than one of these patterns. Since karst aquifers typically contain both thermally effective and ineffective routes, we argue that the thermal response is strongly influenced by recharge mode. ?? 2010 The Author(s). Journal compilation ?? 2010 National Ground Water Association.

Large displacement spring-like electro-mechanical thermal actuators with insulator constraint beams

NASA Astrophysics Data System (ADS)

Luo, J. K.; Fu, Y. Q.; Flewitt, A. J.; Spearing, S. M.; Fleck, N. A.; Milne, W. I.

2005-07-01

A number of in-plane spring-like micro-electro-thermal-actuators with large displacements were proposed. The devices take the advantage of the large difference in the thermal expansion coefficients between the conductive arms and the insulator clamping beams. The constraint beams in one type (the spring) of these devices are horizontally positioned to restrict the expansion of the active arms in the x-direction, and to produce a displacement in the y-direction only. In other two types of actuators (the deflector and the contractor), the constraint beams are positioned parallel to the active arms. When the constraint beams are on the inside of the active arms, the actuator produces an outward deflection in the y-direction. When they are on the outside of the active arms, the actuator produces an inward contraction. Analytical model and finite element analysis were used to simulate the performances. It showed that at a constant temperature, analytical model is sufficient to predict the displacement of these devices. The displacements are all proportional to the temperature and the number of the chevron sections. A two-mask process is under development to fabricate these devices, using Si3N4 as the insulator beams, and electroplated Ni as the conductive beams.

Lighting Condition Analysis for Mars' Moon Phobos

NASA Technical Reports Server (NTRS)

Li, Zu Qun; de Carufel, Guy; Crues, Edwin Z.; Bielski, Paul

2016-01-01

This study used high fidelity computer simulation to investigate the lighting conditions, specifically the solar radiation flux over the surface, on Phobos. Ephemeris data from the Jet Propulsion Laboratory (JPL) DE405 model was used to model the state of the Sun, Earth, Moon, and Mars. An occultation model was developed to simulate Phobos' self-shadowing and its solar eclipses by Mars. The propagated Phobos state was compared with data from JPL's Horizon system to ensure the accuracy of the result. Results for Phobos lighting conditions over one Martian year are presented, which include the duration of solar eclipses, average solar radiation intensity, surface exposure time, and radiant exposure for both sun tracking and fixed solar arrays. The results show that: Phobos' solar eclipse time varies throughout the Martian year, with longer eclipse durations during the Martian northern spring and fall seasons and no eclipses during the Martian northern summer and winter seasons; solar radiation intensity is close to minimum in late spring and close to maximum in late fall; exposure time per orbit is relatively constant over the surface during the spring and fall but varies with latitude during the summer and winter; and Sun tracking solar arrays generate more energy than a fixed solar array. A usage example of the result is also present in this paper to demonstrate the utility.

TALEs from a spring--superelasticity of Tal effector protein structures.

PubMed

Flechsig, Holger

2014-01-01

Transcription activator-like effectors (TALEs) are DNA-related proteins that recognise and bind specific target sequences to manipulate gene expression. Recently determined crystal structures show that their common architecture reveals a superhelical overall structure that may undergo drastic conformational changes. To establish a link between structure and dynamics in TALE proteins we have employed coarse-grained elastic-network modelling of currently available structural data and implemented a force-probe setup that allowed us to investigate their mechanical behaviour in computer experiments. Based on the measured force-extension curves we conclude that TALEs exhibit superelastic dynamical properties allowing for large-scale global conformational changes along their helical axis, which represents the soft direction in such proteins. For moderate external forcing the TALE models behave like linear springs, obeying Hooke's law, and the investigated structures can be characterised and compared by a corresponding spring constant. We show that conformational flexibility underlying the large-scale motions is not homogeneously distributed over the TALE structure, but instead soft spot residues around which strain is accumulated and which turn out to represent key agents in the transmission of conformational motions are identified. They correspond to the RVD loop residues that have been experimentally determined to play an eminent role in the binding process of target DNA.

TALEs from a Spring – Superelasticity of Tal Effector Protein Structures

PubMed Central

Flechsig, Holger

2014-01-01

Transcription activator-like effectors (TALEs) are DNA-related proteins that recognise and bind specific target sequences to manipulate gene expression. Recently determined crystal structures show that their common architecture reveals a superhelical overall structure that may undergo drastic conformational changes. To establish a link between structure and dynamics in TALE proteins we have employed coarse-grained elastic-network modelling of currently available structural data and implemented a force-probe setup that allowed us to investigate their mechanical behaviour in computer experiments. Based on the measured force-extension curves we conclude that TALEs exhibit superelastic dynamical properties allowing for large-scale global conformational changes along their helical axis, which represents the soft direction in such proteins. For moderate external forcing the TALE models behave like linear springs, obeying Hooke's law, and the investigated structures can be characterised and compared by a corresponding spring constant. We show that conformational flexibility underlying the large-scale motions is not homogeneously distributed over the TALE structure, but instead soft spot residues around which strain is accumulated and which turn out to represent key agents in the transmission of conformational motions are identified. They correspond to the RVD loop residues that have been experimentally determined to play an eminent role in the binding process of target DNA. PMID:25313859

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

Oyunbaatar, Nomin-Erdene; Choi, Young Soo; Lee, Dong-Weon, E-mail: mems@jnu.ac.kr

This paper describes a self-adjustable four-point probe (S4PP) system with a square configuration. The S4PP system consists of 3D polymer coil springs for the independent operation of each tungsten (W) probe, microfluidic channels filled with a nontoxic liquid metal, and a LabView-based control system. The 3D coil springs made by PMMA are fabricated with a 3D printer and are positioned in a small container filled with the non-toxic liquid metal. This unique configuration allows independent self-adjustment of the probe heights for precise measurements of the electrical properties of both flexible and large-step-height microsamples. The feasibility of the fabricated S4PP systemmore » is evaluated by measuring the specific resistance of Cr and Au thin films deposited on silicon wafers. The system is then employed to evaluate the electrical properties of a Au thin film deposited onto a flexible and easily breakable silicon diaphragm (spring constant: ∼3.6 × 10{sup −5} N/m). The resistance of the Cr thin films (thickness: 450 nm) with step heights of 60 and 90 μm is also successfully characterized. These experimental results indicate that the proposed S4PP system can be applied to common metals and semiconductors as well as flexible and large-step-height samples.« less

Constant voltage electro-slag remelting control

DOEpatents

Schlienger, M.E.

1996-10-22

A system for controlling electrode gap in an electro-slag remelt furnace has a constant regulated voltage and an electrode which is fed into the slag pool at a constant rate. The impedance of the circuit through the slag pool is directly proportional to the gap distance. Because of the constant voltage, the system current changes are inversely proportional to changes in gap. This negative feedback causes the gap to remain stable. 1 fig.

(abstract) Characterization of Tree Water Status and Dielectric Constant Changes of North American Boreal Forests in Combination with Synthetic Aperture Radar Remote Sensing

NASA Technical Reports Server (NTRS)

McDonald, K. C.; Zimmerman, R.; Way, J. B.

1994-01-01

The occurrence and magnitude of temporal and spatial tree water status changes in the boreal environment were studied in a floodplain forest in Alaska and in four forest types of Central Canada. Under limited water supply conditions from the rooted soil zone in early spring (freeze/thaw transition) and during summer, trees show declining water potentials. Coincidental change in tree water potential, tree transpiration and tree dielectric constant had been observed in previous studies performed in Mediterranean ecotones. If radar is sensitive to chances in tree water status as reflected through changes in dielectric constant, then radar remote sensing could be used to monitor the water status of forests. The SAR imagery is examined to determine the response of the radar backscatter to the ground based observations of the water status of forest canopies. Comparisons are made between stands and also along the large North-South gradient between sites. Data from SAR are used to examine the radar response to canopy physiological state as related to vegetation freeze/thaw and growing season length.

Cell-flow technique.

PubMed

Hess, George P; Lewis, Ryan W; Chen, Yongli

2014-10-01

Various devices have been used to flow neurotransmitter solutions over cells containing receptors (e.g., ligand-gated ion channels) for whole-cell current recordings. With many of the devices, the orientation between the porthole of the flow device and the cell is not maintained absolutely constant. Orientation is critical for reproducibility in kinetic experiments. To be able to change the composition of the flowing solution during an experiment and still maintain a constant orientation, we use the cell-flow device described here. A peristaltic pump, a stainless steel U-tube, two different sizes of peristaltic tubing, and a solenoid valve are required to create a simple solution exchange system that can rapidly apply and remove solutions over the surface of a cell in tens of milliseconds. This system allows one to test multiple conditions on a cell containing the receptor of interest while constantly "washing" the cell with extracellular buffer solution between experimental applications. The use of the solenoid valve allows for the application of solutions to be precisely timed and controlled by a computer during electrophysiological current recording. © 2014 Cold Spring Harbor Laboratory Press.

Design of a resistive exercise device for use on the Space Shuttle

NASA Technical Reports Server (NTRS)

Carlson, Dennis L.; Durrani, Mohammed; Redilla, Christi L.

1992-01-01

The National Aeronautics and Space Administration in conjunction with the Universities Space Research Association sponsored the design of a Resistive Exercise Device (RED) for use on the Space Shuttle. The device must enable the astronauts to perform a number of exercises to prevent skeletal muscle atrophy and neuromuscular deconditioning in microgravity environments. The RED must fit the requirements for limited volume and weight and must provide a means of restraint during exercise. The design team divided the functions of the device into three major groups: methods of supplying force, methods of adjusting force, and methods of transmitting the force to the user. After analyzing the three main functions of the RED and developing alternatives for each, the design team used a comparative decision process to choose the most feasible components for the overall design. The design team selected the constant force spring alternative for further embodiment. The device consists of an array of different sized constant force springs which can be pinned in different combinations to produce the required output forces. The force is transmitted by means of a shaft and gear system. The final report is divided into four sections. An introduction section discusses the sponsor background, problem background and requirements of the device. The second section covers the alternative designs for each of the main functions. The design solution and pertinent calculations comprises the third section. The final section contains design conclusions and recommendations including topics of future work.

MEMS based Low Cost Piezoresistive Microcantilever Force Sensor and Sensor Module

PubMed Central

Pandya, H. J.; Kim, Hyun Tae; Roy, Rajarshi; Desai, Jaydev P.

2014-01-01

In the present work, we report fabrication and characterization of a low-cost MEMS based piezoresistive micro-force sensor with SU-8 tip using laboratory made silicon-on-insulator (SOI) substrate. To prepare SOI wafer, silicon film (0.8 µm thick) was deposited on an oxidized silicon wafer using RF magnetron sputtering technique. The films were deposited in Argon (Ar) ambient without external substrate heating. The material characteristics of the sputtered deposited silicon film and silicon film annealed at different temperatures (400–1050°C) were studied using atomic force microscopy (AFM) and X-ray diffraction (XRD) techniques. The residual stress of the films was measured as a function of annealing temperature. The stress of the as-deposited films was observed to be compressive and annealing the film above 1050°C resulted in a tensile stress. The stress of the film decreased gradually with increase in annealing temperature. The fabricated cantilevers were 130 µm in length, 40 µm wide and 1.0 µm thick. A series of force-displacement curves were obtained using fabricated microcantilever with commercial AFM setup and the data were analyzed to get the spring constant and the sensitivity of the fabricated microcantilever. The measured spring constant and sensitivity of the sensor was 0.1488N/m and 2.7mV/N. The microcantilever force sensor was integrated with an electronic module that detects the change in resistance of the sensor with respect to the applied force and displays it on the computer screen. PMID:24855449

MEMS based Low Cost Piezoresistive Microcantilever Force Sensor and Sensor Module.

PubMed

Pandya, H J; Kim, Hyun Tae; Roy, Rajarshi; Desai, Jaydev P

2014-03-01

In the present work, we report fabrication and characterization of a low-cost MEMS based piezoresistive micro-force sensor with SU-8 tip using laboratory made silicon-on-insulator (SOI) substrate. To prepare SOI wafer, silicon film (0.8 µm thick) was deposited on an oxidized silicon wafer using RF magnetron sputtering technique. The films were deposited in Argon (Ar) ambient without external substrate heating. The material characteristics of the sputtered deposited silicon film and silicon film annealed at different temperatures (400-1050°C) were studied using atomic force microscopy (AFM) and X-ray diffraction (XRD) techniques. The residual stress of the films was measured as a function of annealing temperature. The stress of the as-deposited films was observed to be compressive and annealing the film above 1050°C resulted in a tensile stress. The stress of the film decreased gradually with increase in annealing temperature. The fabricated cantilevers were 130 µm in length, 40 µm wide and 1.0 µm thick. A series of force-displacement curves were obtained using fabricated microcantilever with commercial AFM setup and the data were analyzed to get the spring constant and the sensitivity of the fabricated microcantilever. The measured spring constant and sensitivity of the sensor was 0.1488N/m and 2.7mV/N. The microcantilever force sensor was integrated with an electronic module that detects the change in resistance of the sensor with respect to the applied force and displays it on the computer screen.

Seasonal changes in circulating gonadal steroid levels and physiological evidence for the presence of intrinsic circannual reproductive cycles in captive finless porpoises Neophocaena asiaeorientalis from the western Inland Sea, Japan.

PubMed

Funasaka, Noriko; Yoshioka, Motoi; Ishibashi, Toshiaki; Tatsukawa, Toshiyuki; Shindo, Hideaki; Takada, Koji; Nakamura, Masayuki; Iwata, Tomohiko; Fujimaru, Kaoru; Tanaka, Taira

2018-04-13

We monitored annual fluctuations of gonadal steroid levels in three sexually mature captive finless porpoises (Neophocaena asiaeorientalis; two males and one female) from two different facilities over 56-91 months. Two animals (one male and one female) were held in an indoor tank with a sunroof (facility A) and the other male was held in an indoor tank without a sunroof (facility B). Water temperatures in both facilities reflected seasonal changes during the study period with a minor difference in the fluctuation pattern. Testosterone levels of the male in facility A were higher from spring to summer every year and exhibited a 12-month cycle. The female showed estrus cycles in 1-month intervals from summer to winter, excluding 2 anestrus years. In contrast, the period of higher testosterone levels of the male in facility B gradually initiated earlier over the years under a constant photoperiod (11.5L:12.5D) and exhibited a 9-month cycle during the first 52 months. After changing the light conditions to a natural photoperiod, its testosterone levels were high from early spring to summer for 3 consecutive years and exhibited a 12-month cycle. Our results showed that under a constant artificial photoperiod, the male in facility B failed to recognize the seasonal changes of a natural external environment, resulting in a 9-month, free-running hormone cycle.

Time response analysis in suspension system design of a high-speed car

NASA Astrophysics Data System (ADS)

Pagwiwoko, Cosmas Pandit

2010-03-01

A land speed record vehicle is designed to run on a flat surface like salt lake where the wheels are normally made from solid metal with a special suspension system. The suspension is designed to provide a stable platform to keep the wheel treads on tract, to insulate the car and the driver from the surface irregularities and to take part of good handling properties. The surface condition of the lake beds is basically flat without undulations but with inconsistent surface textures and ridges. Spring with nonlinear rate is used with the reason that the resistance builds up roughly proportional to the aerodynamic download for keeping the height more nearly constant. The objective of the work is to produce an efficient method for assisting the design of suspension system. At the initial step, the stiffness and the damping constants are determined based on RMS optimization by following the optimization strategy i.e. to minimize the absolute acceleration respect to the relative displacement of the suspension. Power bond graph technique is then used to model the nonlinearity of the components i.e. spring and dashpot of the suspension system. This technique also enables to incorporate the interactions of dynamic response of the vehicle's body with aerodynamic flow as a result of the base excitation of the ground to the wheels. The simulation is conducted on the platform of Simulink-MATLAB and the interactions amongst the components within the system are observed in time domain to evaluate the effectiveness of the suspension.

Intra-ocular pressure normalization technique and equipment

NASA Technical Reports Server (NTRS)

Baehr, E. F. (Inventor)

1979-01-01

A method and apparatus is described for safely reducing abnormally high intraocular pressure in an eye during a predetermined time interval. This allows maintenance of normal intraocular pressure during glaucoma surgery. A pressure regulator of the spring-biassed diaphragm type is provided with additional bias by a column of liquid. The hypodermic needle can be safely inserted into the anterior chamber of the eye. Liquid is then bled out of the column to reduce the bias on the diaphragm of the pressure regulator and, consequently, the output pressure of the regulator. This lowering pressure of the regulator also occurs in the eye by means of a small second bleed path provided between the pressure regulator and the hypodermic needle.

Recent (2008-10) water quality in the Barton Springs segment of the Edwards aquifer and its contributing zone, central Texas, with emphasis on factors affecting nutrients and bacteria

USGS Publications Warehouse

Mahler, Barbara J.; Musgrove, MaryLynn; Sample, Thomas L.; Wong, Corinne I.

2011-01-01

The Barton Springs zone, which comprises the Barton Springs segment of the Edwards aquifer and the watersheds to the west that contribute to its recharge, is in south-central Texas, an area with rapid growth in population and increasing amounts of land area affected by development. During November 2008-March 2010, an investigation of factors affecting the fate and transport of nutrients and bacteria in the Barton Springs zone was conducted by the U.S. Geological Survey (USGS), in cooperation with the Texas Commission on Environmental Quality. The primary objectives of the study were to characterize occurrence of nutrients and bacteria in the Barton Springs zone under a range of flow conditions; to improve understanding of the interaction between surface-water quality and groundwater quality; and to evaluate how factors such as streamflow variability and dilution affect the fate and transport of nutrients and bacteria in the Barton Springs zone. The USGS collected and analyzed water samples from five streams (Barton, Williamson, Slaughter, Bear, and Onion Creeks), two groundwater wells (Marbridge and Buda), and the main orifice of Barton Springs in Austin, Texas. During the period of the study, during which the hydrologic conditions transitioned from exceptional drought to wetter than normal, water samples were collected routinely (every 3 to 4 weeks) from the streams, wells, and spring and, in response to storms, from the streams and spring. All samples were analyzed for major ions, nutrients, the bacterium Escherichia coli, and suspended sediment. During the dry period, the geochemistry of groundwater at the two wells and at Barton Springs was dominated by flow from the aquifer matrix and was relatively similar and unchanging at the three sites. At the onset of the wet period, when the streams began to flow, the geochemistry of groundwater samples from the Marbridge well and Barton Springs changed rapidly, and concentrations of most major ions and nutrients and densities of Escherichia coli became more similar to those of samples from the streams relative to concentrations and densities during the dry period. Geochemical modeling indicated that the proportion of Barton Springs discharge composed of stream recharge increased from about 0-8 percent during the dry period to about 80 percent during the wet period. The transition from exceptional drought to wetter-than-normal conditions resulted in a number of marked changes that highlight factors affecting the fate and transport of nutrients and bacteria and the strong influence of stream recharge on water quality in the Barton Springs segment of the Edwards aquifer and had a pronounced effect on the fate of nitrogen species. Organic nitrogen loaded to and stored in soils during the dry period was nitrified to nitrate when the soils were rewetted, resulting in elevated concentrations of nitrate plus nitrite in streams as these constituents were progressively leached during continued wet weather. Estimated mean monthly loads of organic nitrogen and nitrate plus nitrite in stream recharge and Barton Springs discharge, which were relatively low and constant during the dry period, increased during the wet period. Loads of organic nitrogen, on average, were about six times greater in stream recharge than in Barton Springs discharge, indicating that organic nitrogen likely was being converted to nitrate within the aquifer. Loads of total nitrogen (organic nitrogen plus ammonia and nitrate plus nitrite) in stream recharge (162 kilograms per day) and in Barton Springs discharge (157 kilograms per day) for the period of the investigation were not significantly different. Dilution was not an important factor affecting concentrations of nitrate plus nitrite in the streams or in Barton Springs during the period of this investigation: Concentrations of nitrate plus nitrite did not decrease in streams with increasing stream discharge, and nitrate plus nitrite concentrations measured at Barton

Laminae development in opal-A precipitates associated with seasonal growth of the form-genus Calothrix (Cyanobacteria), Rehai geothermal area, Tengchong, Yunnan Province, China

NASA Astrophysics Data System (ADS)

Jones, Brian; Peng, Xiaotong

2015-04-01

The western discharge apron at Meinuquan (Rehai geothermal area, Yunnan Province, China), which incorporates the upper terrace, terrace front, and lower terrace, is covered with laminated opal-A precipitates that have formed from the spring waters that flow across its surface. Laminae are formed of silicified Calothrix mats or featureless opal-A that contains no microbes, scattered spherical and rod-shaped microbes, and/or rare Calothrix. Rapid silicification of the Calothrix led to preservation of their basal heterocysts, vegetative cells, trichomes, tapering filaments, and laminated and splayed sheaths. The Calothrix mats grew during the dry season when there was maximum sunlight because of low cloud cover. During this time, the mats grew under stable conditions because the water that flowed across the discharge apron was sourced from the springs, and temperature and water geochemistry was more or less constant. Growth of the Calothrix mats decreased during the wet season (April to late September) when sunlight is reduced due to the extensive cloud cover associated with the monsoonal rains. During the wet season, water flowing over the discharge apron is a mixture of rainwater, runoff from the surrounding hillsides, and spring water. Such variable flow conditions, water temperatures, and water geochemistry curtailed microbe growth and impacted silica precipitation. The precipitates at Meinuquan are like those associated with some Icelandic hot springs. Although growth of Calothrix is controlled by sunlight in both settings, the periods of maximum sunlight in China (October-March) and Iceland (June-August) are at different times of the year because of their geographic locations.

Problems with the application of hydrogeological science to regulation of Australian mining projects: Carmichael Mine and Doongmabulla Springs

NASA Astrophysics Data System (ADS)

Currell, Matthew J.; Werner, Adrian D.; McGrath, Chris; Webb, John A.; Berkman, Michael

2017-05-01

Understanding and managing impacts from mining on groundwater-dependent ecosystems (GDEs) and other groundwater users requires development of defensible science supported by adequate field data. This usually leads to the creation of predictive models and analysis of the likely impacts of mining and their accompanying uncertainties. The identification, monitoring and management of impacts on GDEs are often a key component of mine approvals, which need to consider and attempt to minimise the risks that negative impacts may arise. Here we examine a case study where approval for a large mining project in Australia (Carmichael Coal Mine) was challenged in court on the basis that it may result in more extensive impacts on a GDE (Doongmabulla Springs) of high ecological and cultural significance than predicted by the proponent. We show that throughout the environmental assessment and approval process, significant data gaps and scientific uncertainties remained unresolved. Evidence shows that the assumed conceptual hydrogeological model for the springs could be incorrect, and that at least one alternative conceptualisation (that the springs are dependent on a deep fault) is consistent with the available field data. Assumptions made about changes to spring flow as a consequence of mine-induced drawdown also appear problematic, with significant implications for the spring-fed wetlands. Despite the large scale of the project, it appears that critical scientific data required to resolve uncertainties and construct robust models of the springs' relationship to the groundwater system were lacking at the time of approval, contributing to uncertainty and conflict. For this reason, we recommend changes to the approval process that would require a higher standard of scientific information to be collected and reviewed, particularly in relation to key environmental assets during the environmental impact assessment process in future projects.

Spring-mass behavior during exhaustive run at constant velocity in elite triathletes.

PubMed

Rabita, Giuseppe; Slawinski, Jean; Girard, Olivier; Bignet, Frank; Hausswirth, Christophe

2011-04-01

The aims of this study were i) to evaluate changes in leg-spring behavior during an exhaustive run in elite triathletes and ii) to determine whether these modifications were related to an increase in the energy cost of running (Cr). Nine elite triathletes ran to exhaustion on an indoor track at a constant velocity corresponding to 95% of the velocity associated with the maximal oxygen uptake (mean ± SD = 5.1 ± 0.3 m·s(-1), time to exhaustion = 10.7 ± 2.6 min). Vertical and horizontal ground reaction forces were measured every lap (200 m) by a 5-m-long force platform system. Cr was measured from pulmonary gas exchange using a breath-by-breath portable gas analyzer. Leg stiffness (-13.1%, P < 0.05) and peak vertical (-9.2%, P < 0.05) and propulsive (-7.5%, P < 0.001) forces decreased significantly with fatigue, whereas vertical stiffness did not change significantly. Leg and vertical stiffness changes were positively related with modifications of aerial time (R(2) = 0.66, P < 0.01 and R(2) = 0.72, P < 0.01, respectively) and negatively with contact time (R(2) = 0.71, P < 0.01 and R(2) = 0.74, P < 0.01, respectively). Alterations of vertical forces were related with the decrease of the angle of velocity vector at toe off (R(2) = 0.73, P < 0.01). When considering mean values of oxygen uptake, no change was observed from 33% to 100% of the time to exhaustion. However, between one-third and two-thirds of the fatiguing run, negative correlations were observed between oxygen consumption and leg stiffness (R(2) = 0.83, P < 0.001) or vertical stiffness (R(2) = 0.50, P < 0.03). During a constant run to exhaustion, the fatigue induces a stiffness adaptation that modifies the stride mechanical parameters and especially decreases the maximal vertical force. This response to fatigue involves greater energy consumption.

Information and Communications Technology Industry. Industry Study, Spring 2008

DTIC Science & Technology

2008-01-01

notification of developing hazards, contributed to coordination failures in public service emergencies and unnecessary endangerment of public safety...or practices are enacted in areas like finance and child safety, resulting in a sectoral approach that relies on a mix of legislation, regulation

40 CFR 52.329 - Rules and regulations.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 14, 1993, the Governor of Colorado submitted revisions to the State's nonattainment new source review... Springs, and Fort Collins moderate carbon monoxide nonattainment areas, the Greeley not classified carbon monoxide nonattainment area, and the Denver transitional ozone nonattainment area. (b) On January 14, 1993...

Larvae of related Diptera species from thermally contrasting habitats exhibit continuous up-regulation of heat shock proteins and high thermotolerance.

PubMed

Garbuz, David G; Zatsepina, Olga G; Przhiboro, Andrey A; Yushenova, Irina; Guzhova, Irina V; Evgen'ev, Michael B

2008-11-01

A population of Stratiomys japonica, a species belonging to the family Stratiomyidae (Diptera), common name 'soldier flies', occurs in a hot volcanic spring, which is apparently among the most inhospitable environments for animals because of chemical and thermal conditions. Larvae of this species, which naturally often experience temperatures more than 40 degrees C, have constitutively high concentrations of the normally inducible heat-shock protein Hsp70, but very low level of corresponding mRNA. Larvae of three other species of the same family, Stratiomys singularior, Nemotelus bipunctatus and Oxycera pardalina, are confined to different type semi-aquatic habitats with contrasting thermal regime. However, all of them shared the same pattern of Hsp70 expression. Interestingly, heat-shock treatment of S. japonica larvae activates heat-shock factor and significantly induces Hsp70 synthesis, whereas larvae of O. pardalina, a species from constant cold environment, produce significantly less Hsp70 in response to heat shock. Adults of the four species also exhibit lower, but detectable levels of Hsp70 without heat shock. Larvae of all species studied have very high tolerance to temperature stress in comparison with other Diptera species investigated, probably representing an inherent adaptive feature of all Stratiomyidae enabling successful colonization of highly variable and extreme habitats.

Dynamic Characteristics of The DSI-Type Constant-Flow Valves

NASA Astrophysics Data System (ADS)

Kang, Yuan; Hu, Sheng-Yan; Chou, Hsien-Chin; Lee, Hsing-Han

Constant flow valves have been presented in industrial applications or academic studies, which compensate recess pressures of a hydrostatic bearing to resist load fluctuating. The flow rate of constant-flow valves can be constant in spite of the pressure changes in recesses, however the design parameters must be specified. This paper analyzes the dynamic responses of DSI-type constant-flow valves that is designed as double pistons on both ends of a spool with single feedback of working pressure and regulating restriction at inlet. In this study the static analysis presents the specific relationships among design parameters for constant flow rate and the dynamic analyses give the variations around the constant flow rate as the working pressure fluctuates.

Investigations of the effects of particle properties on the wear resistance of the particle reinforced composites using a novel wear model

NASA Astrophysics Data System (ADS)

Prabhu, T. Ram

2016-08-01

A wear model is developed based on the discrete lattice spring-mass approach to study the effects of particle volume fraction, size, and stiffness on the wear resistance of particle reinforced composites. To study these effects, we have considered three volume fractions (10%, 20% and 30%), two sizes (10 × 10 and 4 × 4 sites), and two different stiffness of particles embedded in the matrix in a regular pattern. In this model, we have discretized the composite system (400 × 100 sites) into the lumped masses connected with interaction spring elements in two dimensions. The interaction elements are assumed as linear elastic and ideal plastic under applied forces. Each mass is connected to its first and second nearest neighbors by springs. The matrix and particles sites are differentiated by choosing the different stiffness values. The counter surface is simulated as a rigid body that moves on the composite material at a constant sliding speed along the horizontal direction. The governing equations are formed by equating the spring force between the pair of sites given by Hooke’s law plus external contact forces and the force due to the motion of the site given by the equation of motion. The equations are solved for the plastic strain accumulated in the springs using an explicit time stepping procedure based on a finite difference form of the above equations. If the total strain accumulated in the spring elements connected to a lump mass site exceeds the failure strain, the springs are considered to be broken, and the mass site is removed or worn away from the lattice and accounts as a wear loss. The model predicts that (i) increasing volume fraction, reducing particle size and increasing particle stiffness enhance the wear resistance of the particle reinforced composites, (ii) the particle stiffness is the most significant factor affecting the wear resistance of the composites, and (iii) the wear resistance reduced above the critical volume fraction (Vc), and Vc increases with increasing particle size. Finally, we have qualitatively compared the model results with our previously published experimental results to prove the effectiveness of the model to analysis the complex wear systems.

Seasonal variation in the behaviour of a short-lived rodent.

PubMed

Eccard, Jana A; Herde, Antje

2013-11-15

Short lived, iteroparous animals in seasonal environments experience variable social and environmental conditions over their lifetime. Animals can be divided into those with a "young-of-the-year" life history (YY, reproducing and dying in the summer of birth) and an "overwinter" life history (OW, overwintering in a subadult state before reproducing next spring).We investigated how behavioural patterns across the population were affected by season and sex, and whether variation in behaviour reflects the variation in life history patterns of each season. Applications of pace-of-life (POL) theory would suggest that long-lived OW animals are shyer in order to increase survival, and YY are bolder in order to increase reproduction. Therefore, we expected that in winter and spring samples, when only OW can be sampled, the animals should be shyer than in summer and autumn, when both OW and YY animals can be sampled.We studied common vole (Microtus arvalis) populations, which express typical, intra-annual density fluctuation. We captured a total of 492 voles at different months over 3 years and examined boldness and activity level with two standardised behavioural experiments. Behavioural variables of the two tests were correlated with each other. Boldness, measured as short latencies in both tests, was extremely high in spring compared to other seasons. Activity level was highest in spring and summer, and higher in males than in females. Being bold in laboratory tests may translate into higher risk-taking in nature by being more mobile while seeking out partners or valuable territories. Possible explanations include asset-protection, with OW animals being rather old with low residual reproductive value in spring. Therefore, OW may take higher risks during this season. Offspring born in spring encounter a lower population density and may have higher reproductive value than offspring of later cohorts. A constant connection between life history and animal personality, as suggested by the POL theory, however, was not found. Nevertheless, correlations of traits suggest the existence of animal personalities. In conclusion, complex patterns of population dynamics, seasonal variation in life histories, and variability of behaviour due to asset-protection may cause complex seasonal behavioural dynamics in a population.

Acid-base regulation during heating and cooling in the lizard, Varanus exanthematicus.

PubMed

Wood, S C; Johansen, K; Glass, M L; Hoyt, R W

1981-04-01

Current concepts of acid-base balance in ectothermic animals require that arterial pH vary inversely with body temperature in order to maintain a constant OH-/H+ and constant net charge on proteins. The present study evaluates acid-base regulation in Varanus exanthematicus under various regimes of heating and cooling between 15 and 38 degrees C. Arterial blood was sampled during heating and cooling at various rates, using restrained and unrestrained animals with and without face masks. Arterial pH was found to have a small temperature dependence, i.e., pH = 7.66--0.005 (T). The slope (dpH/dT = -0.005), while significantly greater than zero (P less than 0.05), is much less than that required for a constant OH-/H+ or a constant imidazole alphastat (dpH/dT congruent to 0.018). The physiological mechanism that distinguishes this species from most other ectotherms is the presence of a ventilatory response to temperature-induced changes in CO2 production and O2 uptake, i.e., VE/VO2 is constant. This results in a constant O2 extraction and arterial saturation (approx. 90%), which is adaptive to the high aerobic requirements of this species.

ncreasing altitudinal spring phenology gradient of vegetation over the last decade in Qinghai-Tibetan Plateau

NASA Astrophysics Data System (ADS)

Shen, M.; Piao, S.

2013-12-01

Vegetation spring phenology in temperate and cold regions is widely expected to advance with temperature elevation and is often used as an indicator of regional climatic change. The Qinghai-Tibetan Plateau (QTP) has experienced intensive warming recently, but substantial contradictions exist about the changes of vegetation spring phenology. We investigated spatiotemporal variations in green-up dates in the QTP from 2000 to 2011 determined through five methods using four satellite-derived datasets including the normalized difference vegetation index (NDVI) from the Advanced Very High Resolution Radiometer (AVHRR), Système Pour l'Observation de la Terre, and MODerate resolution Imaging Spectroradiometer (MODIS), and the enhanced vegetation index from MODIS. On regional scale, no significant temporal trends (all P > 0.05) were found in the green-up dates, consistently among all the vegetation indices and methods. This insignificance was resulted from the substantial spatial heterogeneity of trends in green-up date, with delay by greater than 0.5 day yr-1 in the southwest region, and extensive advance in the other areas, although the temperature elevation was region-wide. These changes doubled the altitudinal gradient of green-up date, from 0.63 day 100m-1 in the early 2000s to 1.30 days 100m-1 in the early 2010s. The delay in the southwest region and high altitudes was likely caused by the decline in spring precipitation, despite the increasing spring temperature. This study suggests that spring precipitation is an important regulator of phenological response to climatic warming in QTP, and that, even in cold region, delay of vegetation spring phenology does not necessarily indicate spring cooling. Besides, the phenological changes retrieved from the widely used AVHRR NDVI differed from those from the other 3 vegetation indices, necessitating the use of multi-datasets while monitoring vegetation dynamics from space.

Effects of ground-water withdrawals on flow in the Sauk River Valley Aquifer and on streamflow in the Cold Spring area, Minnesota

USGS Publications Warehouse

Lindgren, R.J.

2001-01-01

The simulated contributing areas for selected watersupply wells in the Cold Spring area generally extend to and possibly beyond the model boundaries to the north and to the southeast. The contributing areas for the Gold'n Plump Poultry Processing Plant supply wells extend: (1) to the Sauk River, (2) to the north to and possibly beyond to the northern model boundary, and (3) to the southeast to and possibly beyond the southeastern model boundary. The primary effects of projected increased ground-water withdrawals of 0.23 cubic feet per second (7.5 percent increase) were to: (1) decrease outflow from the Sauk River Valley aquifer through constant-head boundaries and (2) decrease leakage from the valley unit of the Sauk River Valley aquifer to the streams. No appreciable differences were discernible between the simulated steady-state contributing areas to wells with 1998 pumpage and those with the projected pumpage.

Bespoke optical springs and passive force clamps from shaped dielectric particles

NASA Astrophysics Data System (ADS)

Simpson, S. H.; Phillips, D. B.; Carberry, D. M.; Hanna, S.

2013-09-01

By moulding optical fields, holographic optical tweezers are able to generate structured force fields with magnitudes and length scales of great utility for experiments in soft matter and biological physics. It has recently been noted that optically induced force fields are determined not only by the incident optical field, but by the shape and composition of the particles involved [Gluckstad J. Optical manipulation: sculpting the object. Nat Photonics 2011;5:7-8]. Indeed, there are desirable but simple attributes of a force field, such as orientational control, that cannot be introduced by sculpting optical fields alone. With this insight in mind, we show, theoretically, how relationships between force and displacement can be controlled by optimizing particle shapes. We exhibit a constant force optical spring, made from a tapered microrod and discuss methods by which it could be fabricated. In addition, we investigate the optical analogue of streamlining, and show how objects can be shaped so as to reduce the effects of radiation pressure, and hence switch from non-trapping to trapping regimes.

Molecular Simulations of The Formation of Gold-Molecule-Gold Junctions

NASA Astrophysics Data System (ADS)

Wang, Huachuan

2013-03-01

We perform classical molecular simulations by combining grand canonical Monte Carlo (GCMC) sampling with molecular dynamics (MD) simulation to explore the dynamic gold nanojunctions in a Alkenedithiol (ADT) solvent. With the aid of a simple driving-spring model, which can reasonably represent the long-range elasticity of the gold electrode, the spring forces are obtained during the dynamic stretching procedure. A specific multi-time-scale double reversible reference system propagator (double-RESPA) algorithm has been designed for the metal-organic complex in MD simulations to identify the detailed metal-molecule bonding geometry at metal-molecule-metal interface. We investigate the variations of bonding sites of ADT molecules on gold nanojunctions at Au (111) surface at a constant chemical potential. Simulation results show that an Au-ADT-Au interface is formed on Au nanojunctions, bond-breaking intersection is at 1-1 bond of the monatomic chain of the cross-section, instead of at the Au-S bond. Breaking force is around 1.5 nN. These are consistent with the experimental measurements.

Transport properties of elastically coupled fractional Brownian motors

NASA Astrophysics Data System (ADS)

Lv, Wangyong; Wang, Huiqi; Lin, Lifeng; Wang, Fei; Zhong, Suchuan

2015-11-01

Under the background of anomalous diffusion, which is characterized by the sub-linear or super-linear mean-square displacement in time, we proposed the coupled fractional Brownian motors, in which the asymmetrical periodic potential as ratchet is coupled mutually with elastic springs, and the driving source is the external harmonic force and internal thermal fluctuations. The transport mechanism of coupled particles in the overdamped limit is investigated as the function of the temperature of baths, coupling constant and natural length of the spring, the amplitude and frequency of driving force, and the asymmetry of ratchet potential by numerical stimulations. The results indicate that the damping force involving the information of historical velocity leads to the nonlocal memory property and blocks the traditional dissipative motion behaviors, and it even plays a cooperative role of driving force in drift motion of the coupled particles. Thus, we observe various non-monotonic resonance-like behaviors of collective directed transport in the mediums with different diffusion exponents.

Inertia-Controlled Twinning in Ni-Mn-Ga Actuators: A Discrete Twin-Boundary Dynamics Study

NASA Astrophysics Data System (ADS)

Faran, Eilon; Riccardi, Leonardo; Shilo, Doron

2017-09-01

A discrete twin-boundary modeling approach is applied for simulating the dynamic magnetomechanical response of a Ni-Mn-Ga actuator over a wide frequency range. The model is based on experimentally measured kinetic relation of individual twin boundaries and takes into account inertial forces due to acceleration of the actuator's mass. The calculated results show good agreement with experimental measurements performed on a specially designed Ni-Mn-Ga linear spring-mass actuator. In addition, the simulation reveals several new effects that have not been considered before and can be applied to the design of improved actuators. It is identified that the demagnetization effect plays a role of an "effective spring" and results in a resonance-type response. The effects of the actuator's mass and the twin-boundary density on the resonance response and the actuator performance are explored numerically. In particular, it is shown that mass-inertia poses an inherent upper limit over the actuator's bandwidth, which is approximately constant and equals to about 200 Hz.

Altered regulation of TERMINAL FLOWER 1 causes the unique vernalisation response in an arctic woodland strawberry accession.

PubMed

Koskela, Elli A; Kurokura, Takeshi; Toivainen, Tuomas; Sønsteby, Anita; Heide, Ola M; Sargent, Daniel J; Isobe, Sachiko; Jaakola, Laura; Hilmarsson, Hrannar; Elomaa, Paula; Hytönen, Timo

2017-11-01

Vernalisation requirement is an agriculturally important trait that postpones the development of cold-sensitive floral organs until the spring. The family Rosaceae includes many agriculturally important fruit and berry crops that suffer from crop losses caused by frost injury to overwintering flower buds. Recently, a vernalisation-requiring accession of the Rosaceae model woodland strawberry (Fragaria vesca) has been identified in northern Norway. Understanding the molecular basis of the vernalisation requirement in this accession would advance the development of strawberry cultivars better adapted to temperate climate. We use gene silencing, gene expression analysis, genetic mapping and population genomics to study the genetic basis of the vernalisation requirement in woodland strawberry. Our results indicate that the woodland strawberry vernalisation requirement is endemic to northern Norwegian population, and mapping data suggest the orthologue of TERMINAL FLOWER1 (FvTFL1) as the causal floral repressor. We demonstrate that exceptionally low temperatures are needed to downregulate FvTFL1 and to make these plants competent to induce flowering at low postvernalisation temperatures in the spring. We show that altered regulation of FvTFL1 in the northern Norwegian woodland strawberry accession postpones flower induction until the spring, allowing plants to avoid winter injuries of flower buds that commonly occur in temperate regions. © 2017 The Authors New Phytologist © 2017 New Phytologist Trust.

Damping element for reducing the vibration of an airfoil

DOEpatents

Campbell, Christian X; Marra, John J

2013-11-12

An airfoil (10) is provided with a tip (12) having an opening (14) to a center channel (24). A damping element (16) is inserted within the opening of the center channel, to reduce an induced vibration of the airfoil. The mass of the damping element, a spring constant of the damping element within the center channel, and/or a mounting location (58) of the damping element within the center channel may be adjustably varied, to shift a resonance frequency of the airfoil outside a natural operating frequency of the airfoil.

Surface and through crack problems in orthotropic plates

NASA Technical Reports Server (NTRS)

Erdogan, F.; Wu, B.-H.

1988-01-01

The present treatment of the general mode I crack problem in bending- and membrane-loaded orthotropic plates proceeds by formulating the bending problem for a series of planar and through-cracks; by independently varying the six independent constants, the effect of material orthotropy on the stress intensity factor is determined. The surface-crack problem is then formulated by means of the line-spring model, using a transverse-shear theory of plate bending. Attention is given to composite laminates with through-cracks or semielliptic surface cracks. A significant effect is noted for material orthotropy.

(DARPA) Optical Radiation Cooling and Heating In Integrated Devices: Circuit cavity optomechanics for cooling and amplification on a silicon chip

DTIC Science & Technology

2015-07-16

0.02(λ/ n )3 modal volumes while preserving optical cavity Q up to5×106 [Fig. 4(f)-(i)]. The mechanical mode is modeled to have fundamental resonance Qm...addition, a 30.64-MHz resonance is observed and identified as one of the wineglass modes (circumferential number n = 4, “square” mode [40]) with a measured...main challenge is that mechanical resonators operating at high frequencies are extremely stiff, having spring constant on the order of 107 N /m. This

High-temperature fiber optic pressure sensor

NASA Technical Reports Server (NTRS)

Berthold, J. W.

1984-01-01

Attention is given to a program to develop fiber optic methods to measure diaphragm deflection. The end application is intended for pressure transducers capable of operating to 540 C. In this paper are reported the results of a laboratory study to characterize the performance of the fiber-optic microbend sensor. The data presented include sensitivity and spring constant. The advantages and limitations of the microbend sensor for static pressure measurement applications are described. A proposed design is presented for a 540 C pressure transducer using the fiber optic microbend sensor.

Glass transition temperature of polymer nano-composites with polymer and filler interactions

NASA Astrophysics Data System (ADS)

Hagita, Katsumi; Takano, Hiroshi; Doi, Masao; Morita, Hiroshi

2012-02-01

We systematically studied versatile coarse-grained model (bead spring model) to describe filled polymer nano-composites for coarse-grained (Kremer-Grest model) molecular dynamics simulations. This model consists of long polymers, crosslink, and fillers. We used the hollow structure as the filler to describe rigid spherical fillers with small computing costs. Our filler model consists of surface particles of icosahedra fullerene structure C320 and a repulsive force from the center of the filler is applied to the surface particles in order to make a sphere and rigid. The filler's diameter is 12 times of beads of the polymers. As the first test of our model, we study temperature dependence of volumes of periodic boundary conditions under constant pressures through NPT constant Andersen algorithm. It is found that Glass transition temperature (Tg) decrease with increasing filler's volume fraction for the case of repulsive interaction between polymer and fillers and Tg weakly increase for attractive interaction.

Stress drop with constant, scale independent seismic efficiency and overshoot

USGS Publications Warehouse

Beeler, N.M.

2001-01-01

To model dissipated and radiated energy during earthquake stress drop, I calculate dynamic fault slip using a single degree of freedom spring-slider block and a laboratory-based static/kinetic fault strength relation with a dynamic stress drop proportional to effective normal stress. The model is scaled to earthquake size assuming a circular rupture; stiffness varies inversely with rupture radius, and rupture duration is proportional to radius. Calculated seismic efficiency, the ratio of radiated to total energy expended during stress drop, is in good agreement with laboratory and field observations. Predicted overshoot, a measure of how much the static stress drop exceeds the dynamic stress drop, is higher than previously published laboratory and seismic observations and fully elasto-dynamic calculations. Seismic efficiency and overshoot are constant, independent of normal stress and scale. Calculated variation of apparent stress with seismic moment resembles the observational constraints of McGarr [1999].

36 CFR 21.7 - Health examinations.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 36 Parks, Forests, and Public Property 1 2014-07-01 2014-07-01 false Health examinations. 21.7... SPRINGS NATIONAL PARK; BATHHOUSE REGULATIONS § 21.7 Health examinations. No employee who comes in direct... health examination, or remain in such employment without undergoing periodic health examinations, as...

36 CFR 21.7 - Health examinations.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 36 Parks, Forests, and Public Property 1 2013-07-01 2013-07-01 false Health examinations. 21.7... SPRINGS NATIONAL PARK; BATHHOUSE REGULATIONS § 21.7 Health examinations. No employee who comes in direct... health examination, or remain in such employment without undergoing periodic health examinations, as...

36 CFR 21.7 - Health examinations.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Health examinations. 21.7... SPRINGS NATIONAL PARK; BATHHOUSE REGULATIONS § 21.7 Health examinations. No employee who comes in direct... health examination, or remain in such employment without undergoing periodic health examinations, as...

36 CFR 21.7 - Health examinations.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 36 Parks, Forests, and Public Property 1 2011-07-01 2011-07-01 false Health examinations. 21.7... SPRINGS NATIONAL PARK; BATHHOUSE REGULATIONS § 21.7 Health examinations. No employee who comes in direct... health examination, or remain in such employment without undergoing periodic health examinations, as...

36 CFR 21.7 - Health examinations.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 36 Parks, Forests, and Public Property 1 2012-07-01 2012-07-01 false Health examinations. 21.7... SPRINGS NATIONAL PARK; BATHHOUSE REGULATIONS § 21.7 Health examinations. No employee who comes in direct... health examination, or remain in such employment without undergoing periodic health examinations, as...

77 FR 34349 - Endangered and Threatened Species; Take of Anadromous Fish

Federal Register 2010, 2011, 2012, 2013, 2014

2012-06-11

... and Threatened Species; Take of Anadromous Fish AGENCY: National Marine Fisheries Service (NMFS... Department of Fish and Wildlife (ODFW) pursuant to the protective regulations promulgated for Pacific salmon... hatchery fish to support fishing opportunities while minimizing potential risks to natural-origin spring...

Effects of bedrock geology on source and flowpath of runoff water in steep unchanneled hollows

NASA Astrophysics Data System (ADS)

Uchida, T.; Asano, Y.; Kosugi, K.; Ohte, N.; Mizuyama, T.

2001-05-01

Simultaneous measurements of runoff, soil pore water pressure and soil temperature were taken to evaluate the spatial and temporal nature of flowpaths and flow sources in steep unchanneled hollows in central Japan. Two small hollows were monitored; one is underlain by granite and one is underlain by Paleozoic shale. In both catchments, tensiometers showed that a saturated area formed in the areas near a spring. The soil temperature suggests that in the small perennially saturated area near the spring, water percolating through the vadose zone mixed with water emerging from the bedrock. During rainstorms, the streamflow varied with the soil pore water pressure on the upper slope; the soil pore water pressure in the area near the spring remained nearly constant._@ Moreover, the spring water temperature was almost the same as the transient groundwater temperature on the upper slope. This indicates that the transient groundwater in the upper slope flowed to the spring via lateral preferential paths in both catchments. During summer rainstorms, the soil-bedrock interface temperature increased as the ground became saturated in the granite hollow, suggesting that both rainwater and shallow soil water had important effects on the formation of transient saturated groundwater on the upper slope. That is, it can be concluded that the contribution of the bedrock groundwater to the streamflow was relatively small in the granite hollow during storm runoff. The area where the bedrock groundwater seeped into the soil mantle did not grow in size as the contributing area for the streamflow extended to the upper hollow in the granite catchment. In contrast, the soil temperature indicated that after heavy rainfall (77.5 mm), bedrock groundwater played an important role in the formation of the transient groundwater in the Paleozoic shale hollow. Consequently, the contribution of the bedrock groundwater to the streamflow was relatively large in the shale hollow after heavy rainfall.

Bacterial Activity and Geochemical Reactions in Submerged Cave Development -- Impact on Karst Aquifers in Florida

NASA Astrophysics Data System (ADS)

Herman, J. S.; Franklin, R. B.; Mills, A. L.; Giannotti, A. L.; Tysall, T. N.

2008-05-01

Elucidation of coupled mechanisms of sulfide oxidation and biomass generation supports an improved understanding the driving forces behind acid production, calcite dissolution, cave development, and karst aquifers characterization. Wekiwa Springs Cave and DeLeon Springs Cave, located in central Florida, both contain prolific bacterial mats from which sulfur-oxidizing bacteria have been identified. Wekiwa Springs Cave, a submerged cave developed in the Hawthorne Formation and located near Orlando, Florida, has groundwater discharge from the Floridian aquifer system, with some contribution from surficial and intermediate aquifers. The spring is the headwater of the Wekiwa River and releases a total of 170,000 m3 of water per day. The ceiling and walls are heavily covered (10 cm thick) with three morphologically distinct types of microbial mats largely comprising sulfur-oxidizing bacteria. Analysis of nearby groundwater collected from wells confirms sulfide concentrations in the regional groundwater of ~ 1.5 mg/L, though sulfide concentrations for water collected in the cave are below detection. Dissolved oxygen concentration in the water is low (<0.5 mg/L). DeLeon Springs Cave, a submerged cave located in Volusia County, Florida, is a single conduit with an average discharge of ~ 70,000 m3 of water per day, and water chemistry data suggest the presence of a saline seep in the system. Dense microbial mats cover the rock surfaces of the cave; the mats are highly filamentous, with long white streamers that often extend 1-2 feet from the cave wall. Microscopic analysis has confirmed the presence of sulfur granules within these bacterial cells, similar to those observed in the Wekiwa cave organisms. The water chemistry in DeLeon Springs Cave, however, is distinct from that of Wekiwa Springs Cave. Though DO, Fetotal, and HS- values are similar for the two sites, the concentration of ions such as Cl-, Na+, and SO42- are considerably higher at DeLeon. A similar contrast exists for the other major cations (Ca2+, Mg2+, K+), although the difference is less pronounced. An important difference between the two cave systems is the considerable spatial variability associated with water chemistry along the flowpath in the DeLeon system, whereas water chemistry is fairly constant at all locations sampled in Wekiwa Springs Cave. Microbial communities were characterized based on the on overall genetic similarity between whole-community DNA samples as compared using T-RFLP analysis of 16S rRNA genes. The microbial communities found at each sampling station in the Wekiwa Springs Cave are relatively similar to one another, while the communities found at the different sampling stations in the DeLeon Springs Cave are distinct from one another and from the Wekiwa community. This examination of submerged caves with respect to the specific speleogenic mechanisms and the importance of biological processes in their generation informs our understanding of caves and karst environments.

Proteomic Analysis of Albumins and Globulins from Wheat Variety Chinese Spring and Its Fine Deletion Line 3BS-8

PubMed Central

Ma, Chao-Ying; Gao, Li-Yan; Li, Ning; Li, Xiao-Hui; Ma, Wu-Jun; Appels, Rudi; Yan, Yue-Ming

2012-01-01

The relationship between chromosome deletion in wheat and protein expression were investigated using Chinese Spring and fine deletion line 3BS-8. Through 2-DE (2-D electrophoresis) analysis, no differentially expressed proteins (DEPs) were found in leaf samples; however, 47 DEPs showed at least two-fold abundance variation (p < 0.05) in matured wheat grains and 21 spots were identified by tandem MALDI-TOF/TOF-MS. Among the identified spots, four were cultivar-specific, including three (spots B15, B16, and B21) in Chinese Spring and one in 3BS-8 (spot B10). Among variety-different DEPs between Chinese Spring and 3BS-8, most spots showed a higher express profile in CS; only four spots showed up-regulated expression tendency in 3BS-8. An interesting observation was that more than half of the identified protein spots were involved in storage proteins, of which 11 spots were identified as globulins. According to these results, we can presume that the encoded genes of protein spots B15, B16, and B21 were located on the chromosome segment deleted in 3BS-8. PMID:23202959

Inventory of thermal springs and wells within a one-mile radius of Yucca Lodge, Truth or Consequences, New Mexico

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

Schwab, G.E.

1982-02-01

Equity Management Corporation proposes (1) to build about 30 condominiums at the present site of the Yucca Lodge, Truth or Consequences, New Mexico and (2) to heat the condominiums with the natural thermal waters that discharge from the property. To do so the corporation must satisfy the rules and regulations of four state and federal agencies. To satisfy some of the data requirements of these agencies and to provide basic data on the geohydrology of the area this report provides the results of a field inventory of the springs and wells within one mile of the lodge. Table 1 summarizesmore » the data for eight springs and three sites where springs once issued. Table 2 summarizes the data on forty-four operable wells and thirty wells that are unusable in their present condition. Appendices list (1) wells presumed to be in the area but not located during field inspection and (2) wells that could be in the area, but were found to be beyond the one-mile radius. Temperature and specific conductance of the water show only minor variation within the recognized hot-water.« less

Hardware Model of a Shipboard Generator

DTIC Science & Technology

2009-05-19

controller output PM motor power RM motor resistance Td derivative time constant Tf1 fuel valve time constant Tg1 governor time constant Tg2 governor...in speed, sending a response signal to the fuel valve that regulates gas turbine power. At this point, there is an inherent variation between the...basic response analysis [5]. 29 Electrical Power Rotor Inertia Amplifiers Fuel Valve Turbine Dynamics Rotational Friction and Windage

Lack of circadian regulation of melatonin rhythms in the sockeye salmon (Oncorhynchus nerka) in vivo and in vitro.

PubMed

Iigo, Masayuki; Azuma, Teruo; Iwata, Munehico

2007-01-01

Melatonin profiles were determined in the plasma in vivo and in the pineal organ in vitro of the sockeye salmon (Oncorhynchus nerka) under various light conditions to test whether they are under circadian regulation. When serial blood samples were taken at 4-h intervals for 3 days via a cannula inserted into the dorsal aorta, plasma melatonin exhibited significant fluctuation under a light-dark cycle, with higher levels during the dark phase than during the light phase. No rhythmic fluctuations persisted under either constant dark or constant light, with constant low and high levels, respectively. Melatonin release from the pineal organ in flow-through culture exhibited a similar pattern in response to the change in light conditions, with high and low release associated with the dark and light phases, respectively. These results indicate that melatonin production in the sockeye salmon is driven by light and darkness but lacks circadian regulation.

Circadian rhythms of temperature and activity in obese and lean Zucker rats

NASA Technical Reports Server (NTRS)

Murakami, D. M.; Horwitz, B. A.; Fuller, C. A.

1995-01-01

The circadian timing system is important in the regulation of feeding and metabolism, both of which are aberrant in the obese Zucker rat. This study tested the hypothesis that these abnormalities involve a deficit in circadian regulation by examining the circadian rhythms of body temperature and activity in lean and obese Zucker rats exposed to normal light-dark cycles, constant light, and constant dark. Significant deficits in both daily mean and circadian amplitude of temperature and activity were found in obese Zucker female rats relative to lean controls in all lighting conditions. However, the circadian period of obese Zucker rats did not exhibit differences relative to lean controls in either of the constant lighting conditions. These results indicate that although the circadian regulation of temperature and activity in obese Zucker female rats is in fact depressed, obese rats do exhibit normal entrainment and pacemaker functions in the circadian timing system. The results suggest a deficit in the process that generates the amplitude of the circadian rhythm.

Tactual discrimination of softness.

PubMed

Srinivasan, M A; LaMotte, R H

1995-01-01

1. We investigated the ability of humans to tactually discriminate the softness of objects, using novel elastic objects with deformable and rigid surfaces. For objects with deformable surfaces, we cast transparent rubber specimens with variable compliances. For objects with rigid surfaces ("spring cells") we fabricated telescoping hollow cylinders with the inner cylinder supported by several springs. To measure the human discriminability and to isolate the associated information-processing mechanisms, we performed psychophysical experiments under three conditions: 1) active touch with the normal finger, where both tactile and kinesthetic information was available to the subject: 2) active touch with local cutaneous anesthesia, so that only kinesthetic information was available; and 3) passive touch, where a computer-controlled mechanical stimulator brought down the compliant specimens onto the passive fingerpad of the subject, who therefore had only tactile information. 2. We first characterized the mechanical behavior of the human fingerpad and the test objects by determining the relationship between the depth and force of indentation during constant-velocity indentations by a rigid probe. The fingerpad exhibited a pronounced nonlinear behavior in the indentation depth versus force trace such that compliance, as indicated by the local slope of the trace, decreased with increases in indentation depth. The traces for all the rubber specimens were approximately linear, indicating a constant but distinct value of compliance for each specimen. The fingerpad was more compliant than each of the rubber specimens. 3. All the human subjects showed excellent softness discriminability in ranking the rubber specimens by active touch, and the subjective perception of softness correlated one-to-one with the objectively measured compliance. The ability of subjects to discriminate the compliance of spring cells was consistently poorer compared with that of the rubber specimens. 4. For pairwise discrimination of a selected set of rubber specimens, kinesthetic information alone was insufficient. However, tactile information alone was sufficient, even when the velocities and forces of specimen application were randomized. In contrast, for discriminating pairs of spring cells, tactile information alone was insufficient, and both tactile and kinesthetic information were found to be necessary. 5. The differences in the sufficiency of tactile information for the discrimination of the two types of objects can be explained by the mechanics of contact of the fingerpad and its effect on tactile information. For objects with deformable surfaces, the spatial pressure distribution within the contact region depends on both the force applied and the specimen compliance.(ABSTRACT TRUNCATED AT 250 WORDS)

36 CFR 21.10 - Losses.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Losses. 21.10 Section 21.10 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR HOT SPRINGS NATIONAL PARK; BATHHOUSE REGULATIONS § 21.10 Losses. A bathhouse receiving deposits of jewelry, money, or...

36 CFR 21.9 - Solicitation by employees.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 36 Parks, Forests, and Public Property 1 2011-07-01 2011-07-01 false Solicitation by employees. 21.9 Section 21.9 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR HOT SPRINGS NATIONAL PARK; BATHHOUSE REGULATIONS § 21.9 Solicitation by employees. Soliciting by...

36 CFR 21.8 - Employee certification.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 36 Parks, Forests, and Public Property 1 2012-07-01 2012-07-01 false Employee certification. 21.8 Section 21.8 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR HOT SPRINGS NATIONAL PARK; BATHHOUSE REGULATIONS § 21.8 Employee certification. (a) Employees engaged as...

36 CFR 21.5 - Therapeutic bathing requirements.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Therapeutic bathing requirements. 21.5 Section 21.5 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR HOT SPRINGS NATIONAL PARK; BATHHOUSE REGULATIONS § 21.5 Therapeutic bathing requirements. Baths...

36 CFR 21.8 - Employee certification.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 36 Parks, Forests, and Public Property 1 2013-07-01 2013-07-01 false Employee certification. 21.8 Section 21.8 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR HOT SPRINGS NATIONAL PARK; BATHHOUSE REGULATIONS § 21.8 Employee certification. (a) Employees engaged as...

36 CFR 21.5 - Therapeutic bathing requirements.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 36 Parks, Forests, and Public Property 1 2012-07-01 2012-07-01 false Therapeutic bathing requirements. 21.5 Section 21.5 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR HOT SPRINGS NATIONAL PARK; BATHHOUSE REGULATIONS § 21.5 Therapeutic bathing requirements. Baths...

36 CFR 21.8 - Employee certification.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 36 Parks, Forests, and Public Property 1 2011-07-01 2011-07-01 false Employee certification. 21.8 Section 21.8 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR HOT SPRINGS NATIONAL PARK; BATHHOUSE REGULATIONS § 21.8 Employee certification. (a) Employees engaged as...

36 CFR 21.9 - Solicitation by employees.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Solicitation by employees. 21.9 Section 21.9 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR HOT SPRINGS NATIONAL PARK; BATHHOUSE REGULATIONS § 21.9 Solicitation by employees. Soliciting by...

36 CFR 21.2 - Penalties.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 36 Parks, Forests, and Public Property 1 2014-07-01 2014-07-01 false Penalties. 21.2 Section 21.2 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR HOT SPRINGS NATIONAL PARK; BATHHOUSE REGULATIONS § 21.2 Penalties. Any person convicted of violating any provision of...

36 CFR 21.2 - Penalties.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Penalties. 21.2 Section 21.2 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR HOT SPRINGS NATIONAL PARK; BATHHOUSE REGULATIONS § 21.2 Penalties. Any person convicted of violating any provision of...

36 CFR 21.2 - Penalties.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 36 Parks, Forests, and Public Property 1 2011-07-01 2011-07-01 false Penalties. 21.2 Section 21.2 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR HOT SPRINGS NATIONAL PARK; BATHHOUSE REGULATIONS § 21.2 Penalties. Any person convicted of violating any provision of...

36 CFR 21.8 - Employee certification.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Employee certification. 21.8 Section 21.8 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR HOT SPRINGS NATIONAL PARK; BATHHOUSE REGULATIONS § 21.8 Employee certification. (a) Employees engaged as...

36 CFR 21.5 - Therapeutic bathing requirements.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 36 Parks, Forests, and Public Property 1 2014-07-01 2014-07-01 false Therapeutic bathing requirements. 21.5 Section 21.5 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR HOT SPRINGS NATIONAL PARK; BATHHOUSE REGULATIONS § 21.5 Therapeutic bathing requirements. Baths...

36 CFR 21.2 - Penalties.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 36 Parks, Forests, and Public Property 1 2012-07-01 2012-07-01 false Penalties. 21.2 Section 21.2 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR HOT SPRINGS NATIONAL PARK; BATHHOUSE REGULATIONS § 21.2 Penalties. Any person convicted of violating any provision of...

36 CFR 21.9 - Solicitation by employees.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 36 Parks, Forests, and Public Property 1 2013-07-01 2013-07-01 false Solicitation by employees. 21.9 Section 21.9 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR HOT SPRINGS NATIONAL PARK; BATHHOUSE REGULATIONS § 21.9 Solicitation by employees. Soliciting by...

36 CFR 21.9 - Solicitation by employees.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 36 Parks, Forests, and Public Property 1 2014-07-01 2014-07-01 false Solicitation by employees. 21.9 Section 21.9 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR HOT SPRINGS NATIONAL PARK; BATHHOUSE REGULATIONS § 21.9 Solicitation by employees. Soliciting by...

36 CFR 21.5 - Therapeutic bathing requirements.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 36 Parks, Forests, and Public Property 1 2013-07-01 2013-07-01 false Therapeutic bathing requirements. 21.5 Section 21.5 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR HOT SPRINGS NATIONAL PARK; BATHHOUSE REGULATIONS § 21.5 Therapeutic bathing requirements. Baths...

36 CFR 21.10 - Losses.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 36 Parks, Forests, and Public Property 1 2012-07-01 2012-07-01 false Losses. 21.10 Section 21.10 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR HOT SPRINGS NATIONAL PARK; BATHHOUSE REGULATIONS § 21.10 Losses. A bathhouse receiving deposits of jewelry, money, or...

36 CFR 21.10 - Losses.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 36 Parks, Forests, and Public Property 1 2014-07-01 2014-07-01 false Losses. 21.10 Section 21.10 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR HOT SPRINGS NATIONAL PARK; BATHHOUSE REGULATIONS § 21.10 Losses. A bathhouse receiving deposits of jewelry, money, or...

36 CFR 21.5 - Therapeutic bathing requirements.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 36 Parks, Forests, and Public Property 1 2011-07-01 2011-07-01 false Therapeutic bathing requirements. 21.5 Section 21.5 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR HOT SPRINGS NATIONAL PARK; BATHHOUSE REGULATIONS § 21.5 Therapeutic bathing requirements. Baths...

36 CFR 21.10 - Losses.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 36 Parks, Forests, and Public Property 1 2013-07-01 2013-07-01 false Losses. 21.10 Section 21.10 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR HOT SPRINGS NATIONAL PARK; BATHHOUSE REGULATIONS § 21.10 Losses. A bathhouse receiving deposits of jewelry, money, or...

36 CFR 21.10 - Losses.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 36 Parks, Forests, and Public Property 1 2011-07-01 2011-07-01 false Losses. 21.10 Section 21.10 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR HOT SPRINGS NATIONAL PARK; BATHHOUSE REGULATIONS § 21.10 Losses. A bathhouse receiving deposits of jewelry, money, or...

36 CFR 21.2 - Penalties.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 36 Parks, Forests, and Public Property 1 2013-07-01 2013-07-01 false Penalties. 21.2 Section 21.2 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR HOT SPRINGS NATIONAL PARK; BATHHOUSE REGULATIONS § 21.2 Penalties. Any person convicted of violating any provision of...

36 CFR 21.8 - Employee certification.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 36 Parks, Forests, and Public Property 1 2014-07-01 2014-07-01 false Employee certification. 21.8 Section 21.8 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR HOT SPRINGS NATIONAL PARK; BATHHOUSE REGULATIONS § 21.8 Employee certification. (a) Employees engaged as...

36 CFR 21.9 - Solicitation by employees.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 36 Parks, Forests, and Public Property 1 2012-07-01 2012-07-01 false Solicitation by employees. 21.9 Section 21.9 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR HOT SPRINGS NATIONAL PARK; BATHHOUSE REGULATIONS § 21.9 Solicitation by employees. Soliciting by...

A dynamic leaf gas-exchange strategy is conserved in woody ...

EPA Pesticide Factsheets

Rising atmospheric [CO2], ca, is expected to affect stomatal regulation of leaf gas-exchange of woody plants, thus influencing energy fluxes as well as carbon (C), water and nutrient cycling of forests. Researchers have reported that stomata regulate leaf gas-exchange around “set points” that include a constant leaf internal [CO2], ci, a constant drawdown in CO2 (ca - ci), and a constant ci/ca. Because these set points can result in drastically different consequences for leaf gas-exchange, it will be essential for the accuracy of Earth systems models that generalizable patterns in leaf gas-exchange responses to ca be identified if any do exist. We hypothesized that the concept of optimal stomatal behavior, exemplified by woody plants shifting along a continuum of these set point strategies, would provide a unifying framework for understanding leaf gas-exchange responses to ca. We analyzed studies reporting C stable isotope ratio (δ13C) or photosynthetic discrimination (∆13C) from woody plant taxa that grew across ca spanning at least 100 ppm for each species investigated. From these data we calculated ci, and in combination with known or estimated ca, leaf gas-exchange regulation strategies were assessed. Overall, our analyses does not support the hypothesis that trees are canalized towards any of the proposed set points, particularly so for a constant ci. Rather, the results are consistent with the hypothesis that stomatal optimization regulates leaf gas

Direct measurements of forces between different charged colloidal particles and their prediction by the theory of Derjaguin, Landau, Verwey, and Overbeek (DLVO)

NASA Astrophysics Data System (ADS)

Ruiz-Cabello, F. Javier Montes; Maroni, Plinio; Borkovec, Michal

2013-06-01

Force measurements between three types of latex particles of diameters down to 1 μm with sulfate and carboxyl surface functionalities were carried out with the multi-particle colloidal probe technique. The experiments were performed in monovalent electrolyte up to concentrations of about 5 mM. The force profiles could be quantified with the theory of Derjaguin, Landau, Verwey, and Overbeek (DLVO) by invoking non-retarded van der Waals forces and the Poisson-Boltzmann description of double layer forces within the constant regulation approximation. The forces measured in the symmetric systems were used to extract particle and surface properties, namely, the Hamaker constant, surface potentials, and regulation parameters. The regulation parameter is found to be independent of solution composition. With these values at hand, the DLVO theory is capable to accurately predict the measured forces in the asymmetric systems down to distances of 2-3 nm without adjustable parameters. This success indicates that DLVO theory is highly reliable to quantify interaction forces in such systems. However, charge regulation effects are found to be important, and they must be considered to obtain correct description of the forces. The use of the classical constant charge or constant potential boundary conditions may lead to erroneous results. To make reliable predictions of the force profiles, the surface potentials must be extracted from direct force measurements too. For highly charged surfaces, the commonly used electrophoresis techniques are found to yield incorrect estimates of this quantity.

Direct measurements of forces between different charged colloidal particles and their prediction by the theory of Derjaguin, Landau, Verwey, and Overbeek (DLVO).

PubMed

Montes Ruiz-Cabello, F Javier; Maroni, Plinio; Borkovec, Michal

2013-06-21

Force measurements between three types of latex particles of diameters down to 1 μm with sulfate and carboxyl surface functionalities were carried out with the multi-particle colloidal probe technique. The experiments were performed in monovalent electrolyte up to concentrations of about 5 mM. The force profiles could be quantified with the theory of Derjaguin, Landau, Verwey, and Overbeek (DLVO) by invoking non-retarded van der Waals forces and the Poisson-Boltzmann description of double layer forces within the constant regulation approximation. The forces measured in the symmetric systems were used to extract particle and surface properties, namely, the Hamaker constant, surface potentials, and regulation parameters. The regulation parameter is found to be independent of solution composition. With these values at hand, the DLVO theory is capable to accurately predict the measured forces in the asymmetric systems down to distances of 2-3 nm without adjustable parameters. This success indicates that DLVO theory is highly reliable to quantify interaction forces in such systems. However, charge regulation effects are found to be important, and they must be considered to obtain correct description of the forces. The use of the classical constant charge or constant potential boundary conditions may lead to erroneous results. To make reliable predictions of the force profiles, the surface potentials must be extracted from direct force measurements too. For highly charged surfaces, the commonly used electrophoresis techniques are found to yield incorrect estimates of this quantity.

Stream temperature medelling and fibre optic distributed temperature sensing to quantify groundwater discharge in the Ngongotaha Stream, New Zealand

NASA Astrophysics Data System (ADS)

Moridnejad, Maryam; Cameron, Stewart; Shamseldin, Asaad; Ward, Nick Dudley; Verhagen, Floris

2015-04-01

To characterize stream/groundwater interaction, fibre optic distributed temperature sensing (FODTS) was deployed over a 1 km reach in the Ngongotaha Stream, Rotorua, New Zealand in January 2013. The cable was deployed at the streambed near the left and right banks as the groundwater fed springs discharge laterally at both banks. Temperature profiles measured by FODTS were used to identify the location of springs using a constant temperature method (20 min averaged temperature data) (Lowry et al., 2007; Matheswaran et al., 2014; Selker et al., 2006a) and a standard deviation of diurnal temperature method (Lowry et al., 2007; Matheswaran et al., 2014). Both methods identified 13 individual springs at the right and left banks in an approximately 115 m reach. The left and right bank temperature profiles showed that full mixing of the spring and stream water does not occur between most of the springs due to their close spacing. Groundwater discharge quantification based on FODTS data is typically made using a simple steady state thermal mixing model (Briggs et al., 2012a; Selker et al.,2006a; Westhoff et al., 2007). This formula is not applicable in streams like the Ngongotaha where springs are closely spaced and groundwater and surface water are not well mixed between springs. To address this issue, a new approach was developed in this study in which a one dimensional heat transport model was fitted to the FODTS measurements, where the main calibration parameters of interest were the unknown spring discharges. Datasets of measured temperatures at the left and right bank were transformed to a new single dataset using a weighted average where the weights reflect the degree of mixing downstream of a spring. Model calibration helped to find the optimum value of the weights in the springs section. For a spring on the left bank the weighted average was skewed towards the left bank data, and vice-versa for a right bank spring. Upstream of the spring section, a non-weighted average was applied. Streamflow gauging upstream and downstream of the study reach showed that the stream gains ~ 500 L/s from groundwater which was used to find the mixing ratios of the left and right banks. The new model allowed the spring discharge to be quantified in the complex hydrogeological setting. The results showed consistency with the findings of previous study in the Ngongotaha Stream catchment (Kov'ǎcov'a et al., 2008). Refrences Briggs, M. A., Lautz, L. K., McKenzie, J. M., 2012a. A comparison of fibre-optic distributed temperature sensing to traditional methods of evaluating groundwater inflow to streams. Hydrological Processes 26 (9), 1277-1290. Kov'ǎcov'a, E., White, P., (N.Z.), G. S., Staff, G. S. N., 2008. Groundwater Catchments for Individual Springs in Ngongotaha andWaiowhiro Surface Catchments, Lake Rotorua. GNS Science report. GNS Science. Lowry, C. S., Walker, J. F., Hunt, R. J., Anderson, M. P., 2007. Identifying spatial variability of groundwater discharge in a wetland stream using a distributed temperature sensor. Water Resources Research 43 (10). Matheswaran, K., Blemmer, M., Rosbjerg, D., Boegh, E., 2014. Seasonal variations in groundwater upwelling zones in a danish lowland stream analyzed using distributed temperature sensing (dts). Hydrological Processes 28 (3), 1422-1435. Selker, J., van de Giesen, N., Westhoff, M., Luxemburg, W., Parlange, M. B., 2006a. Fiber optics opens window on stream dynamics. Geophysical Research Letters 33 (24). Westhoff, M. C., Savenije, H. H. G., Luxemburg, W. M. J. ., Stelling, G. S., van de Giesen, N. C., Selker, J. S., Pfister, L., Uhlenbrook, S., 2007. A distributed stream temperature model using high resolution temperature observations. Hydrology and Earth System Sciences 11 (4), 1469-1480.

Constant pH Accelerated Molecular Dynamics Investigation of the pH Regulation Mechanism of Dinoflagellate Luciferase.

PubMed

Donnan, Patrick H; Ngo, Phong D; Mansoorabadi, Steven O

2018-01-23

The bioluminescence reaction in dinoflagellates involves the oxidation of an open-chain tetrapyrrole by the enzyme dinoflagellate luciferase (LCF). The activity of LCF is tightly regulated by pH, where the enzyme is essentially inactive at pH ∼8 and optimally active at pH ∼6. Little is known about the mechanism of LCF or the structure of the active form of the enzyme, although it has been proposed that several intramolecularly conserved histidine residues in the N-terminal region are important for the pH regulation mechanism. Here, constant pH accelerated molecular dynamics was employed to gain insight into the conformational activation of LCF induced by acidification.

Methods for estimating selected spring and fall low-flow frequency statistics for ungaged stream sites in Iowa, based on data through June 2014

USGS Publications Warehouse

Eash, David A.; Barnes, Kimberlee K.; O'Shea, Padraic S.

2016-09-19

A statewide study was led to develop regression equations for estimating three selected spring and three selected fall low-flow frequency statistics for ungaged stream sites in Iowa. The estimation equations developed for the six low-flow frequency statistics include spring (April through June) 1-, 7-, and 30-day mean low flows for a recurrence interval of 10 years and fall (October through December) 1-, 7-, and 30-day mean low flows for a recurrence interval of 10 years. Estimates of the three selected spring statistics are provided for 241 U.S. Geological Survey continuous-record streamgages, and estimates of the three selected fall statistics are provided for 238 of these streamgages, using data through June 2014. Because only 9 years of fall streamflow record were available, three streamgages included in the development of the spring regression equations were not included in the development of the fall regression equations. Because of regulation, diversion, or urbanization, 30 of the 241 streamgages were not included in the development of the regression equations. The study area includes Iowa and adjacent areas within 50 miles of the Iowa border. Because trend analyses indicated statistically significant positive trends when considering the period of record for most of the streamgages, the longest, most recent period of record without a significant trend was determined for each streamgage for use in the study. Geographic information system software was used to measure 63 selected basin characteristics for each of the 211streamgages used to develop the regional regression equations. The study area was divided into three low-flow regions that were defined in a previous study for the development of regional regression equations.Because several streamgages included in the development of regional regression equations have estimates of zero flow calculated from observed streamflow for selected spring and fall low-flow frequency statistics, the final equations for the three low-flow regions were developed using two types of regression analyses—left-censored and generalized-least-squares regression analyses. A total of 211 streamgages were included in the development of nine spring regression equations—three equations for each of the three low-flow regions. A total of 208 streamgages were included in the development of nine fall regression equations—three equations for each of the three low-flow regions. A censoring threshold was used to develop 15 left-censored regression equations to estimate the three fall low-flow frequency statistics for each of the three low-flow regions and to estimate the three spring low-flow frequency statistics for the southern and northwest regions. For the northeast region, generalized-least-squares regression was used to develop three equations to estimate the three spring low-flow frequency statistics. For the northeast region, average standard errors of prediction range from 32.4 to 48.4 percent for the spring equations and average standard errors of estimate range from 56.4 to 73.8 percent for the fall equations. For the northwest region, average standard errors of estimate range from 58.9 to 62.1 percent for the spring equations and from 83.2 to 109.4 percent for the fall equations. For the southern region, average standard errors of estimate range from 43.2 to 64.0 percent for the spring equations and from 78.1 to 78.7 percent for the fall equations.The regression equations are applicable only to stream sites in Iowa with low flows not substantially affected by regulation, diversion, or urbanization and with basin characteristics within the range of those used to develop the equations. The regression equations will be implemented within the U.S. Geological Survey StreamStats Web-based geographic information system application. StreamStats allows users to click on any ungaged stream site and compute estimates of the six selected spring and fall low-flow statistics; in addition, 90-percent prediction intervals and the measured basin characteristics for the ungaged site are provided. StreamStats also allows users to click on any Iowa streamgage to obtain computed estimates for the six selected spring and fall low-flow statistics.

Demographic analysis of dormancy and survival in the terrestrial orchid Cypripedium reginae

USGS Publications Warehouse

Kery, Marc; Gregg, Katharine B.

2004-01-01

1. We use capture-recapture models to estimate the fraction of dormant ramets, survival and state transition rates, and to identify factors affecting these rates, for the terrestrial orchid Cypripedium reginae. We studied two populations in West Virginia, USA, for 11 years and investigated relationships between grazing and demography. Abe Run's population was small, with moderate herbivory by deer and relatively constant population size. The population at Big Draft was of medium size, with heavy deer grazing, and a sharply declining number of flowering plants up to the spring before our study started, when the population was fenced. 2. We observed dormant episodes lasting from 1 to 4 years. At Abe Run and Big Draft, 32.5% and 7.4% of ramets, respectively, were dormant at least once during the study period for an average of 1.6 and 1.3 years, respectively. We estimated the annual fraction of ramets in the dormant state at 12.3% (95% CI 9.5-15.8%) at Abe Run and at 1.8% (95% CI 1.2-2.6%) at Big Draft. Transition rates between the dormant, vegetative and flowering life-states did not vary between years in either population. Most surviving ramets remained in the same state from one year to the next. Survival rates were constant at Abe Run (0.96, 95% CI 0.93-0.97), but varied between years at Big Draft (0.89-0.99, mean 0.95). 3. At Big Draft, we found neither a temporal trend in survival after cessation of grazing, nor relationships between survival and the number of spring frost days or cumulative precipitation during the current or the previous 12 months. However, analysis of precipitation on a 3-month basis revealed a positive relationship between survival and precipitation during the spring (March-May) of the previous year. 4. Relationship between climate and the population dynamics of orchids may have to be studied with a fine temporal resolution, and considering possible time lags. Capture-recapture modelling provides a comprehensive and flexible framework for demographic analysis of plants with dormancy.

An efficient biological pathway layout algorithm combining grid-layout and spring embedder for complicated cellular location information

PubMed Central

2010-01-01

Background Graph drawing is one of the important techniques for understanding biological regulations in a cell or among cells at the pathway level. Among many available layout algorithms, the spring embedder algorithm is widely used not only for pathway drawing but also for circuit placement and www visualization and so on because of the harmonized appearance of its results. For pathway drawing, location information is essential for its comprehension. However, complex shapes need to be taken into account when torus-shaped location information such as nuclear inner membrane, nuclear outer membrane, and plasma membrane is considered. Unfortunately, the spring embedder algorithm cannot easily handle such information. In addition, crossings between edges and nodes are usually not considered explicitly. Results We proposed a new grid-layout algorithm based on the spring embedder algorithm that can handle location information and provide layouts with harmonized appearance. In grid-layout algorithms, the mapping of nodes to grid points that minimizes a cost function is searched. By imposing positional constraints on grid points, location information including complex shapes can be easily considered. Our layout algorithm includes the spring embedder cost as a component of the cost function. We further extend the layout algorithm to enable dynamic update of the positions and sizes of compartments at each step. Conclusions The new spring embedder-based grid-layout algorithm and a spring embedder algorithm are applied to three biological pathways; endothelial cell model, Fas-induced apoptosis model, and C. elegans cell fate simulation model. From the positional constraints, all the results of our algorithm satisfy location information, and hence, more comprehensible layouts are obtained as compared to the spring embedder algorithm. From the comparison of the number of crossings, the results of the grid-layout-based algorithm tend to contain more crossings than those of the spring embedder algorithm due to the positional constraints. For a fair comparison, we also apply our proposed method without positional constraints. This comparison shows that these results contain less crossings than those of the spring embedder algorithm. We also compared layouts of the proposed algorithm with and without compartment update and verified that latter can reach better local optima. PMID:20565884

21 CFR 868.2700 - Pressure regulator.

Code of Federal Regulations, 2010 CFR

2010-04-01

... purposes and that is used to convert a medical gas pressure from a high variable pressure to a lower, more constant working pressure. This device includes mechanical oxygen regulators. (b) Classification. Class I...

Dust aerosols above the south polar cap of Mars as seen by OMEGA

NASA Astrophysics Data System (ADS)

Vincendon, M.; Langevin, Y.; Poulet, F.; Bibring, J.-P.; Gondet, B.; Jouglet, D.; Omega Team

2008-08-01

The time evolution of atmospheric dust at high southern latitudes on Mars has been determined using observations of the south seasonal cap acquired in the near infrared (1-2.65 μm) by OMEGA/Mars Express in 2005. Observations at different solar zenith angles and one EPF sequence demonstrate that the reflectance in the 2.64 μm saturated absorption band of the surface CO 2 ice is mainly due to the light scattered by aerosols above most places of the seasonal cap. We have mapped the total optical depth of dust aerosols in the near-IR above the south seasonal cap of Mars from mid-spring to early summer with a time resolution ranging from one day to one week and a spatial resolution of a few kilometers. The optical depth above the south perennial cap is determined on a longer time range covering southern spring and summer. A constant set of optical properties of dust aerosols is consistent with OMEGA observations during the analyzed period. Strong variations of the optical depth are observed over small horizontal and temporal scales, corresponding in part to moving dust clouds. The late summer peak in dust opacity observed by Opportunity in 2005 propagated to the south pole contrarily to that observed in mid spring. This may be linked to evidence for dust scavenging by water ice-rich clouds circulating at high southern latitudes at this season.

Modelling of human walking to optimise the function of ankle-foot orthosis in Guillan-Barré patients with drop foot.

PubMed

Jamshidi, N; Rostami, M; Najarian, S; Menhaj, M B; Saadatnia, M; Firooz, S

2009-04-01

This paper deals with the dynamic modelling of human walking. The main focus of this research was to optimise the function of the orthosis in patients with neuropathic feet, based on the kinematics data from different categories of neuropathic patients. The patient's body on the sagittal plane was modelled for calculating the torques generated in joints. The kinematics data required for mathematical modelling of the patients were obtained from the films of patients captured by high speed camera, and then the films were analysed through a motion analysis software. An inverse dynamic model was used for estimating the spring coefficient. In our dynamic model, the role of muscles was substituted by adding a spring-damper between the shank and ankle that could compensate for their weakness by designing ankle-foot orthoses based on the kinematics data obtained from the patients. The torque generated in the ankle was varied by changing the spring constant. Therefore, it was possible to decrease the torque generated in muscles which could lead to the design of more comfortable and efficient orthoses. In this research, unlike previous research activities, instead of studying the abnormal gait or modelling the ankle-foot orthosis separately, the function of the ankle-foot orthosis on the abnormal gait has been quantitatively improved through a correction of the torque.

Kineto-dynamic design optimisation for vehicle-specific seat-suspension systems

NASA Astrophysics Data System (ADS)

Shangguan, Wen-Bin; Shui, Yijie; Rakheja, Subhash

2017-11-01

Designs and analyses of seat-suspension systems are invariably performed considering effective vertical spring rate and damping properties, while neglecting important contributions due to kinematics of the widely used cross-linkage mechanism. In this study, a kineto-dynamic model of a seat-suspension is formulated to obtain relations for effective vertical suspension stiffness and damping characteristics as functions of those of the air spring and the hydraulic damper, respectively. The proposed relations are verified through simulations of the multi-body dynamic model of the cross-linkage seat-suspension in the ADAMS platform. The validity of the kineto-dynamic model is also demonstrated through comparisons of its vibration transmission response with the experimental data. The model is used to identify optimal air spring coordinates to attain nearly constant natural frequency of the suspension, irrespective of the seated body mass and seated height. A methodology is further proposed to identify optimal damping requirements for vehicle-specific suspension designs to achieve minimal seat effective amplitude transmissibility (SEAT) and vibration dose value (VDV) considering vibration spectra of different classes of earthmoving vehicles. The shock and vibration isolation performance potentials of the optimal designs are evaluated under selected vehicle vibration superimposed with shock motions. Results show that the vehicle-specific optimal designs could provide substantial reductions in the SEAT and VDV values for the vehicle classes considered.

Hydrogeology and hydrogeochemistry at a site of strategic importance: the Pareja Limno-reservoir drainage basin (Guadalajara, central Spain)

NASA Astrophysics Data System (ADS)

Molina-Navarro, Eugenio; Sastre-Merlín, Antonio; Vicente, Rosa; Martínez-Pérez, Silvia

2014-08-01

A small calcareous basin in central Spain was studied to establish the role of groundwater in the Pareja Limno-reservoir. Limno-reservoirs aim to preserve a constant water level in the riverine zone of large reservoirs to mitigate the impacts arising from their construction. Groundwater flow contribution (mean 60 %) was derived by recharge estimation. In situ measurements (spring discharge, electrical conductivity and sulfate) were undertaken and spring discharge was compared with a drought index. Twenty-eight springs were monitored and three hydrogeological units (HGUs) were defined: a carbonate plateau (HGU1), the underlying aquitard (HGU2), and the gypsum-enriched HGU3. HGU1 is the main aquifer and may play a role in the preservation of the limno-reservoir water level. Hydrogeochemical sampling was conducted and the code PHREEQC used to describe the main geochemical processes. Weathering and dissolution of calcite and gypsum seem to control the hydrogeochemical processes in the basin. Water progresses from Ca2+-HCO3 - in the upper basin to Ca2+-SO4 2- in the lower basin, where HGU3 outcrops. A clear temporal pattern was observed in the limno-reservoir, with salinity decreasing in winter and increasing in summer. This variation was wider at the river outlet, but the mixing of the river discharge with limno-reservoir water buffered it.

How important is hydrotherapy? Effects of dynamic action of hot spring water as a rehabilitative treatment for burn patients in Switzerland.

PubMed

Moufarrij, S; Deghayli, L; Raffoul, W; Hirt-Burri, N; Michetti, M; de Buys Roessingh, A; Norberg, M; Applegate, L A

2014-12-31

Burn rehabilitation using hydrotherapy can have multiple benefits for the burn patient. The therapy uses specific mineral enriched hot spring water and water jets with varied hydro-pressure to combat hypertrophy, inflammatory reaction signs, abnormal pigmentation, and, more specifically, redness and scarring. Standard operating procedures for burn rehabilitation have been developed and integrated into the Standard of Care at the CHUV hospital using localized hydro-mechanical stimulation of burn sites (20 minutes of alternating anatomical sites) followed by constant pressure large-bore and filiform showers targeting specific scarred areas. These therapeutic regimens are repeated daily for 2 to 3 weeks. Patients showed lasting effects from this regimen (up to 3-6 months), the results becoming permanent with more uniform skin structure, color and visco-elasticity in addition to a decrease in pruritus. The specifications of clinical protocols are described herein along with the virtues of hot spring hydro-pressure therapy for burn rehabilitation. The use of hydrotherapy, which has been a controversial topic among burn units across the world, is also discussed. In North America, hydrotherapy is defined only within the scope of in-patient wound cleansing and is thought to lead to microbial auto-contamination and bacterial resistance. In Switzerland and France the emphasis of hydrotherapy is on rehabilitation after the wound has closed.

How important is hydrotherapy? Effects of dynamic action of hot spring water as a rehabilitative treatment for burn patients in Switzerland

PubMed Central

Moufarrij, S.; Deghayli, L.; Raffoul, W.; Hirt-Burri, N.; Michetti, M.; de Buys Roessingh, A.; Norberg, M.; Applegate, L.A.

2014-01-01

Summary Burn rehabilitation using hydrotherapy can have multiple benefits for the burn patient. The therapy uses specific mineral enriched hot spring water and water jets with varied hydro-pressure to combat hypertrophy, inflammatory reaction signs, abnormal pigmentation, and, more specifically, redness and scarring. Standard operating procedures for burn rehabilitation have been developed and integrated into the Standard of Care at the CHUV hospital using localized hydro-mechanical stimulation of burn sites (20 minutes of alternating anatomical sites) followed by constant pressure large-bore and filiform showers targeting specific scarred areas. These therapeutic regimens are repeated daily for 2 to 3 weeks. Patients showed lasting effects from this regimen (up to 3-6 months), the results becoming permanent with more uniform skin structure, color and visco-elasticity in addition to a decrease in pruritus. The specifications of clinical protocols are described herein along with the virtues of hot spring hydro-pressure therapy for burn rehabilitation. The use of hydrotherapy, which has been a controversial topic among burn units across the world, is also discussed. In North America, hydrotherapy is defined only within the scope of in-patient wound cleansing and is thought to lead to microbial auto-contamination and bacterial resistance. In Switzerland and France the emphasis of hydrotherapy is on rehabilitation after the wound has closed. PMID:26336365

A study of the response of nonlinear springs

NASA Technical Reports Server (NTRS)

Hyer, M. W.; Knott, T. W.; Johnson, E. R.

1991-01-01

The various phases to developing a methodology for studying the response of a spring-reinforced arch subjected to a point load are discussed. The arch is simply supported at its ends with both the spring and the point load assumed to be at midspan. The spring is present to off-set the typical snap through behavior normally associated with arches, and to provide a structure that responds with constant resistance over a finite displacement. The various phases discussed consist of the following: (1) development of the closed-form solution for the shallow arch case; (2) development of a finite difference analysis to study (shallow) arches; and (3) development of a finite element analysis for studying more general shallow and nonshallow arches. The two numerical analyses rely on a continuation scheme to move the solution past limit points, and to move onto bifurcated paths, both characteristics being common to the arch problem. An eigenvalue method is used for a continuation scheme. The finite difference analysis is based on a mixed formulation (force and displacement variables) of the governing equations. The governing equations for the mixed formulation are in first order form, making the finite difference implementation convenient. However, the mixed formulation is not well-suited for the eigenvalue continuation scheme. This provided the motivation for the displacement based finite element analysis. Both the finite difference and the finite element analyses are compared with the closed form shallow arch solution. Agreement is excellent, except for the potential problems with the finite difference analysis and the continuation scheme. Agreement between the finite element analysis and another investigator's numerical analysis for deep arches is also good.

Estimation of survival of adult Florida manatees in the Crystal River, at Blue Spring, and on the Atlantic Coast

USGS Publications Warehouse

O'Shea, Thomas J.; Langtimm, Catherine A.; O'Shea, Thomas J.; Ackerman, B.B.; Percival, H. Franklin

1995-01-01

We applied Cormack-Jolly-Seber open population models to manatee (Trichechus manatus latirostris) photo-identification databases to estimate adult survival probabilities. The computer programs JOLLY and RECAPCO were used to estimate survival of 677 individuals in three study areas: Crystal River (winters 1977-78 to 1990-91), Blue Spring (winters 1977-78 to 1990-91), and the Atlantic Coast (winters 1984-85 to 1990-91). We also estimated annual survival from observations of 111 manatees tagged for studies with radiotelemetry. Survival estimated from observations with telemetry had broader confidence intervals than survival estimated with the Cormack-Jolly-Seber models. Annual probabilities of capture based on photo-identification records were generally high. The mean annual adult survival estimated from sighting-resighting records was 0.959-0.962 in the Crystal River and 0.936-0.948 at Blue Spring and may be high enough to permit population growth, given the values of other life-history parameters. On the Atlantic Coast, the estimated annual adult survival (range of means = 0.877-0.885) may signify a declining population. However, for several reasons, interpretation of data from the latter study group should be tempered with caution. Adult survivorship seems to be constant with age in all three study groups. No strong differences were apparent between adult survival ofmales and females in the Crystal River or at Blue Spring; the basis of significant differences between sexes on the Atlantic Coast is unclear. Future research into estimating survival with photo-identification and the Cormack-Jolly-Seber models should be vigorously pursued. Estimates of annual survival can provide an additional indication of Florida manatee population status with a stronger statistical basis than aerial counts and carcass totals.

Low-Velocity Impact Response of Sandwich Beams with Functionally Graded Core

NASA Technical Reports Server (NTRS)

Apetre, N. A.; Sankar, B. V.; Ambur, D. R.

2006-01-01

The problem of low-speed impact of a one-dimensional sandwich panel by a rigid cylindrical projectile is considered. The core of the sandwich panel is functionally graded such that the density, and hence its stiffness, vary through the thickness. The problem is a combination of static contact problem and dynamic response of the sandwich panel obtained via a simple nonlinear spring-mass model (quasi-static approximation). The variation of core Young's modulus is represented by a polynomial in the thickness coordinate, but the Poisson's ratio is kept constant. The two-dimensional elasticity equations for the plane sandwich structure are solved using a combination of Fourier series and Galerkin method. The contact problem is solved using the assumed contact stress distribution method. For the impact problem we used a simple dynamic model based on quasi-static behavior of the panel - the sandwich beam was modeled as a combination of two springs, a linear spring to account for the global deflection and a nonlinear spring to represent the local indentation effects. Results indicate that the contact stiffness of thc beam with graded core Increases causing the contact stresses and other stress components in the vicinity of contact to increase. However, the values of maximum strains corresponding to the maximum impact load arc reduced considerably due to grading of thc core properties. For a better comparison, the thickness of the functionally graded cores was chosen such that the flexural stiffness was equal to that of a beam with homogeneous core. The results indicate that functionally graded cores can be used effectively to mitigate or completely prevent impact damage in sandwich composites.

Influence of running velocity on vertical, leg and joint stiffness : modelling and recommendations for future research.

PubMed

Brughelli, Matt; Cronin, John

2008-01-01

Human running can be modelled as either a spring-mass model or multiple springs in series. A force is required to stretch or compress the spring, and thus stiffness, the variable of interest in this paper, can be calculated from the ratio of this force to the change in spring length. Given the link between force and length change, muscle stiffness and mechanical stiffness have been areas of interest to researchers, clinicians, and strength and conditioning practitioners for many years. This review focuses on mechanical stiffness, and in particular, vertical, leg and joint stiffness, since these are the only stiffness types that have been directly calculated during human running. It has been established that as running velocity increases from slow-to-moderate values, leg stiffness remains constant while both vertical stiffness and joint stiffness increase. However, no studies have calculated vertical, leg or joint stiffness over a range of slow-to-moderate values to maximum values in an athletic population. Therefore, the effects of faster running velocities on stiffness are relatively unexplored. Furthermore, no experimental research has examined the effects of training on vertical, leg or joint stiffness and the subsequent effects on running performance. Various methods of training (Olympic style weightlifting, heavy resistance training, plyometrics, eccentric strength training) have shown to be effective at improving running performance. However, the effects of these training methods on vertical, leg and joint stiffness are unknown. As a result, the true importance of stiffness to running performance remains unexplored, and the best practice for changing stiffness to optimize running performance is speculative at best. It is our hope that a better understanding of stiffness, and the influence of running speed on stiffness, will lead to greater interest and an increase in experimental research in this area.

Estimating Colloidal Contact Model Parameters Using Quasi-Static Compression Simulations.

PubMed

Bürger, Vincent; Briesen, Heiko

2016-10-05

For colloidal particles interacting in suspensions, clusters, or gels, contact models should attempt to include all physical phenomena experimentally observed. One critical point when formulating a contact model is to ensure that the interaction parameters can be easily obtained from experiments. Experimental determinations of contact parameters for particles either are based on bulk measurements for simulations on the macroscopic scale or require elaborate setups for obtaining tangential parameters such as using atomic force microscopy. However, on the colloidal scale, a simple method is required to obtain all interaction parameters simultaneously. This work demonstrates that quasi-static compression of a fractal-like particle network provides all the necessary information to obtain particle interaction parameters using a simple spring-based contact model. These springs provide resistances against all degrees of freedom associated with two-particle interactions, and include critical forces or moments where such springs break, indicating a bond-breakage event. A position-based cost function is introduced to show the identifiability of the two-particle contact parameters, and a discrete, nonlinear, and non-gradient-based global optimization method (simplex with simulated annealing, SIMPSA) is used to minimize the cost function calculated from deviations of particle positions. Results show that, in principle, all necessary contact parameters for an arbitrary particle network can be identified, although numerical efficiency as well as experimental noise must be addressed when applying this method. Such an approach lays the groundwork for identifying particle-contact parameters from a position-based particle analysis for a colloidal system using just one experiment. Spring constants also directly influence the time step of the discrete-element method, and a detailed knowledge of all necessary interaction parameters will help to improve the efficiency of colloidal particle simulations.

53. VIEW OF TIRRILL VOLTAGE REGULATOR LOCATED ON SOUTH WALL ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

53. VIEW OF TIRRILL VOLTAGE REGULATOR LOCATED ON SOUTH WALL OF CONTROL ROOM. THE SOLENOID COILS AT THE TOP RIGHT OF THE PHOTOGRAPH DETECT VARIATIONS IN VOLTAGE AND CURRENT. THE ARMATURES OF THESE COILS ACT ON A SPRING LOADED BEAM. MOVEMENT OF THIS BEAM INDIRECTLY CONTROL SWITCHES WHICH CAUSE RESISTANCE GRIDS TO BE SWITCHED IN OR OUT OF THE EXCITER GENERATOR FIELD COILS (SEE CT-142A-95). - New York, New Haven & Hartford Railroad, Cos Cob Power Plant, Sound Shore Drive, Greenwich, Fairfield County, CT

Unmasking Hb Paksé (codon 142, TAA>TAT, α2) and its combinations in patients also carrying Hb Constant Spring (codon 142, TAA>CAA, α2) in northern Thailand.

PubMed

Pornprasert, Sakorn; Panyasai, Sitthichai; Treesuwan, Kallayanee

2012-01-01

The incidence of Hb Paksé (codon 142, TAA>TAT, α2) might have been underestimated due to misidentifying some cases as Hb Constant Spring (Hb CS, codon 142, TAA>CAA, α2) since both abnormal hemoglobins (Hbs) migrate to the same position on Hb electrophoresis or chromatography. Multiplex asymmetric allele-specific polymerase chain reaction (PCR) for identification of Hb CS and Hb Paksé, and a real-time PCR (ReTi-PCR) with SYBR Green1 high resolution melting (HRM) analysis, for detection of the α-thalassemia-1 (α-thal-1) Southeast Asian (- -(SEA)/) type deletion, were performed on 114 blood samples collected from subjects who lived in northern Thailand. These samples were previously identified as carrying Hb CS by capillary electrophoresis (CE) or high performance liquid chromatography (HPLC). Five out of 114 (4.4%) samples were found to carry Hb Paksé with four different genotypes including Hb Paksé trait, compound Hb CS/Hb Paksé, Hb H-Hb Paksé disease and Hb H-Hb Paksé-Hb E disease. These results suggested that Hb Paksé and its various combinations can be misidentified as Hb CS. Although the clinical symptoms of Hb Paksé and Hb CS are similar, to prevent erroneous epidemiological data on Hb CS as well as underestimating the prevalence of Hb Paksé in northern Thailand, DNA analysis is recommended to be performed in all cases when peaks of Hb CS/Hb Paksé are detected on CE or HPLC.

Force spectroscopy of membrane hardness of SH-SY5Y neuroblastoma cells before and after differentiation

NASA Astrophysics Data System (ADS)

Kwon, Sangwoo; Yang, Woochul; Choi, Yun Kyong; Park, Jung Keuck

2014-05-01

Atomic force microscopy (AFM) is utilized in many studies for measuring the structure and the physical characteristics of soft and bio materials. In particular, the force spectroscopy function in the AFM system allows us to explore the mechanical properties of bio cells. In this study, we probe the variation in the membrane hardness of human neuroblastoma SH-SY5Y cells (SH-cells) before and after differentiation by using force spectroscopy. The SH-cell, which is usually differentiated by using a chemical treatment with retinoic acid (RA), is a neuronal cell line employed widely as an in-vitro model for neuroscience research. In force spectroscopy, the force-distance curves are obtained from both the original and the RA-treated cells while the AFM tip approaches and pushes on the cell membranes. The slope deduced from linear region in the force-distance curve is the spring constant and corresponds to the hardness of the cell membrane. The spring constant of the RA-treated cells (0.597 ± 0.010 nN/nm) was smaller than that of the original cells (0.794 ± 0.010 nN/nm), reflecting a hardness decrease in the cells differentiated with the RA treatments. The results clearly demonstrated that the differentiated cells are softer than the original cells. The change in the elasticity of the differentiated cells might be caused by morphological modification during differentiation process. We suggest that force spectroscopy can be employed as a novel method to determine the degree of differentiation of stem cells into various functional cells.

Modified cantilevers to probe unambiguously out-of-plane piezoresponse

NASA Astrophysics Data System (ADS)

Alyabyeva, Natalia; Ouvrard, Aimeric; Lindfors-Vrejoiu, Ionela; Kolomiytsev, Alexey; Solodovnik, Maxim; Ageev, Oleg; McGrouther, Damien

2018-06-01

We demonstrate and investigate the coupling of contributions from both in-plane (IP) polarization and out-of-plane (OP) components in BiFeO3 (BFO) thin-film polarization probed by piezoresponse force microscopy (PFM). Such coupling leads to image artifacts which prevent the correct determination of OP polarization vector directions and the corresponding piezoelectric coefficient d33. Using material strength theory with a one-dimensional modeling of the cantilever oscillation amplitude under electrostatic and elastic forces as a function of the tip length, we have evidenced the impact of IP piezoresponse to the OP signal for tip length longer than 4 μm. The IP polarization vector induces a significant longitudinal bending of the cantilever, due to the small spring constant of long tips, which provokes a normal deviation superimposed to the OP piezoresponse. These artifacts can be reduced by increasing the longitudinal spring constant of the cantilever by shortening the tip length. Standard cantilevers with 15-μm-long tips were modified to reach the desired tip length, using focused ion-beam techniques and tested using PFM on the same BFO thin film. Tip length shortening has strongly reduced IP artifacts as expected, while the impact of nonlocal electrostatic forces, becoming predominant for tips shorter than 1 μm, has led to a non-negligible deflection offset. For shorter tips, a strong electric field from a cantilever beam can induce polarization switching as observed for a 0.5-μm-long tip. Tip length ranging from 1 to 4 μm allowed minimizing both artifacts to probe unambiguously OP piezoresponse and quantify the d33 piezoelectric coefficient.

The Self-Regulating Brain: Cortical-Subcortical Feedback and the Development of Intelligent Action

ERIC Educational Resources Information Center

Lewis, Marc D.; Todd, Rebecca M.

2007-01-01

To speak of cognitive regulation versus emotion regulation may be misleading. However, some forms of regulation are carried out by executive processes, subject to voluntary control, while others are carried out by "automatic" processes that are far more primitive. Both sets of processes are in constant interaction, and that interaction gives rise…

In vivo testing of a magnetically suspended centrifugal pump designed for long-term use.

PubMed

Yamada, T; Nishimura, K; Akamatsu, T; Tsukiya, T; Park, C H; Kono, S; Matsuda, K; Ban, T

1997-10-01

The life of currently-available centrifugal pumps is limited to no more than three days. As a magnetically suspended centrifugal pump (MSCP) contains no shaft or seal, it could be expected to have a longer life expectancy. The MSCP was evaluated in a chronic animal model using eight adult sheep. Left ventricular assist with the MSCP was instituted between the left atrium and the descending aorta. The flow rates ranged from 2.5 to 6.0 L/min. The duration of the experiments ranged from 14 to 60 days. No mechanical failure occurred. The plasma free hemoglobin levels remained within an acceptable range (3-19 mg/dL). No reduction in the counts of red blood cells or platelets was observed. Thrombus formation within the MSCP was recognized in one pump. The main reason for termination was thromboembolism derived from the circuits. Three types of regulation methods (constant rotational speed, constant motor current, and controlled motor current) were also investigated. Regulation by a constant motor current mode altered the pressure-flow (P-Q) characteristics, and thereby, a steadier pump flow was obtained compared with regulation in the constant rotational speed mode. Moreover, the controlled motor current mode can change the P-Q relationship. These results demonstrate that the MSCP is a promising device for long-term use.

System analysis of the dynamic response of the coronary circulation to a sudden change in heart rate.

PubMed

Dankelman, J; Stassen, H G; Spaan, J A

1990-03-01

In this study the response of driving pressure/flow ration on an abrupt change in heart rate was analysed. The difference between the response obtained with constant pressure and constant flow perfusion was also studied. The responses show a fast initial reversed phase followed by a slow phase caused by regulation. To test whether the initial phase could be the result of mechanical changes in the coronary circulation, a model for regulation was extended by the addition of four different mechanical models originating from the literature. These extended models were able to explain the fast initial phase. However, the mechanical model consisting of an intramyocardial compliance (C = 0.08 ml mm Hg-1 100 g-1) with a variable venous resistance, and the model consisting of a waterfall and a small compliance (C = 0.007 ml mm Hg-1 100g-1) both explained these responses best. The analysis showed that there is no direct relationship between rate of change of vascular tone and rate of change of pressure/flow ratio. However, on the basis of the two extended models, it can be predicted that the half-time for the response of regulation to be complete is about 9s with constant pressure perfusion and 15 s with constant flow perfusion.

Communications--Getting the Act Together.

ERIC Educational Resources Information Center

Canadian Communications Research Information Centre, Ottawa (Ontario).

This document provides a discussion of the policy implications of a proposed bill introduced in the Canadian House of Commons in Spring 1977 relating to the regulation of telecommunications in Canada. This act, which can be viewed as an attempt to make telecommunications more responsive to changing technology and to provincial concerns, seeks to…

77 FR 60179 - Endangered and Threatened Wildlife and Plants; 12-Month Petition Finding, Listing of the Spring...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-10-02

... fluctuating water levels and temperature changes. The incremental and cumulative groundwater recharge effects... quality parameters such as oxygen and temperature, along with changes in water quantity, such as increased... effects in fish species, affecting the immune system, hormone regulation, reproduction, and developmental...

18 CFR 430.7 - Determination of protected areas and restriction on water use.

Code of Federal Regulations, 2010 CFR

2010-04-01

... DELAWARE RIVER BASIN COMMISSION SPECIAL REGULATIONS GROUND WATER PROTECTION AREA: PENNSYLVANIA § 430.7... a protected area within the meaning and for the purpose of Article 10 of the Delaware River Basin.... Boroughs Elverson, Malvern, Phoenixville, Spring City, West Chester. Townships Lehigh County Lower Milford...

21 CFR 812.19 - Address for IDE correspondence.

Code of Federal Regulations, 2011 CFR

2011-04-01

... and Radiological Health, Document Mail Center, 10903 New Hampshire Ave., Bldg. 66, rm. G609, Silver Spring, MD 20993-0002. (2) For devices regulated by the Center for Biologics Evaluation and Research, send it to the Document Control Center (HFM-99), Center for Biologics Evaluation and Research, Food and...

36 CFR 21.11 - Redemption of bath tickets.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 36 Parks, Forests, and Public Property 1 2013-07-01 2013-07-01 false Redemption of bath tickets. 21.11 Section 21.11 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR HOT SPRINGS NATIONAL PARK; BATHHOUSE REGULATIONS § 21.11 Redemption of bath tickets. Unused...

36 CFR 21.11 - Redemption of bath tickets.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 36 Parks, Forests, and Public Property 1 2014-07-01 2014-07-01 false Redemption of bath tickets. 21.11 Section 21.11 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR HOT SPRINGS NATIONAL PARK; BATHHOUSE REGULATIONS § 21.11 Redemption of bath tickets. Unused...

36 CFR 21.11 - Redemption of bath tickets.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Redemption of bath tickets. 21.11 Section 21.11 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR HOT SPRINGS NATIONAL PARK; BATHHOUSE REGULATIONS § 21.11 Redemption of bath tickets. Unused...

36 CFR 21.6 - Use of therapeutic pools.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Use of therapeutic pools. 21.6 Section 21.6 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR HOT SPRINGS NATIONAL PARK; BATHHOUSE REGULATIONS § 21.6 Use of therapeutic pools. Persons undergoing...

36 CFR 21.11 - Redemption of bath tickets.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 36 Parks, Forests, and Public Property 1 2012-07-01 2012-07-01 false Redemption of bath tickets. 21.11 Section 21.11 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR HOT SPRINGS NATIONAL PARK; BATHHOUSE REGULATIONS § 21.11 Redemption of bath tickets. Unused...

36 CFR 21.6 - Use of therapeutic pools.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 36 Parks, Forests, and Public Property 1 2011-07-01 2011-07-01 false Use of therapeutic pools. 21.6 Section 21.6 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR HOT SPRINGS NATIONAL PARK; BATHHOUSE REGULATIONS § 21.6 Use of therapeutic pools. Persons undergoing...

36 CFR 21.6 - Use of therapeutic pools.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 36 Parks, Forests, and Public Property 1 2012-07-01 2012-07-01 false Use of therapeutic pools. 21.6 Section 21.6 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR HOT SPRINGS NATIONAL PARK; BATHHOUSE REGULATIONS § 21.6 Use of therapeutic pools. Persons undergoing...

36 CFR 21.6 - Use of therapeutic pools.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 36 Parks, Forests, and Public Property 1 2014-07-01 2014-07-01 false Use of therapeutic pools. 21.6 Section 21.6 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR HOT SPRINGS NATIONAL PARK; BATHHOUSE REGULATIONS § 21.6 Use of therapeutic pools. Persons undergoing...

36 CFR 21.6 - Use of therapeutic pools.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 36 Parks, Forests, and Public Property 1 2013-07-01 2013-07-01 false Use of therapeutic pools. 21.6 Section 21.6 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR HOT SPRINGS NATIONAL PARK; BATHHOUSE REGULATIONS § 21.6 Use of therapeutic pools. Persons undergoing...

36 CFR 21.11 - Redemption of bath tickets.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 36 Parks, Forests, and Public Property 1 2011-07-01 2011-07-01 false Redemption of bath tickets. 21.11 Section 21.11 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR HOT SPRINGS NATIONAL PARK; BATHHOUSE REGULATIONS § 21.11 Redemption of bath tickets. Unused...

77 FR 68716 - Proposed Amendment of Class E Airspace; Hot Springs, SD

Federal Register 2010, 2011, 2012, 2013, 2014

2012-11-16

... comments through the Internet at http://www.regulations.gov . You may review the public docket containing... 9:00 a.m. and 5:00 p.m., Monday through Friday, except Federal holidays. The Docket Office... regulatory, aeronautical, economic, environmental, and energy-related aspects of the proposal. Communications...

DNA methylation/demethylation programming during peach flower bud dormancy release, development and blooming

USDA-ARS?s Scientific Manuscript database

Peach flower bud development undergoes a long, complex and temperature-dependent regulation process with cessation of growth in response to cool temperatures in late fall, a slow but gradual development during the chilling period in winter, and eventually blooming in early spring. It has been demon...

Soil temperature regulates nitrogen loss from lysimeters following fall and winter manure application

USDA-ARS?s Scientific Manuscript database

Many producers practice fall and winter manure spreading for economic and practical reasons. In order to minimize the risk of nitrogen loss between application and crop uptake in the spring, university extension publications and industry professionals often make recommendations based on soil tempera...

Expression of FcFT1, a FLOWERING LOCUS T-like gene, is regulated by light and associated with inflorescence differentiation in fig (Ficus carica L.).

PubMed

Ikegami, Hidetoshi; Nogata, Hitoshi; Inoue, Yoshiaki; Himeno, Shuichi; Yakushiji, Hiroshi; Hirata, Chiharu; Hirashima, Keita; Mori, Masashi; Awamura, Mitsuo; Nakahara, Takao

2013-12-16

Because the floral induction occurs in many plants when specific environmental conditions are satisfied, most plants bloom and bear fruit during the same season each year. In fig, by contrast, the time interval during which inflorescence (flower bud, fruit) differentiation occurs corresponds to the shoot elongation period. Fig trees thus differ from many species in their reproductive growth characteristics. To date, however, the molecular mechanisms underlying this unorthodox physiology of floral induction and fruit setting in fig trees have not been elucidated. We isolated a FLOWERING LOCUS T (FT)-like gene from fig and examined its function, characteristics, and expression patterns. The isolated gene, F. carica FT (FcFT1), is single copy in fig and shows the highest similarity at the amino acid level (93.1%) to apple MdFT2. We sequenced its upstream region (1,644 bp) and identified many light-responsive elements. FcFT1 was mainly expressed in leaves and induced early flowering in transgenic tobacco, suggesting that FcFT1 is a fig FT ortholog. Real-time reverse-transcription PCR analysis revealed that FcFT1 mRNA expression occurred only in leaves at the lower nodes, the early fruit setting positions. mRNA levels remained a constant for approximately 5 months from spring to autumn, corresponding almost exactly to the inflorescence differentiation season. Diurnal variation analysis revealed that FcFT1 mRNA expression increased under relative long-day and short-day conditions, but not under continuous darkness. These results suggest that FcFT1 activation is regulated by light conditions and may contribute to fig's unique fruit-setting characteristics.

Space shuttle OMS helium regulator design and development

NASA Technical Reports Server (NTRS)

Wichmann, H.; Kelly, T. L.; Lynch, R.

1974-01-01

Analysis, design, fabrication and design verification testing was conducted on the technological feasiblity of the helium pressurization regulator for the space shuttle orbital maneuvering system application. A prototype regulator was fabricated which was a single-stage design featuring the most reliable and lowest cost concept. A tradeoff study on regulator concepts indicated that a single-stage regulator with a lever arm between the valve and the actuator section would offer significant weight savings. Damping concepts were tested to determine the amount of damping required to restrict actuator travel during vibration. Component design parameters such as spring rates, effective area, contamination cutting, and damping were determined by test prior to regulator final assembly. The unit was subjected to performance testing at widely ranging flow rates, temperatures, inlet pressures, and random vibration levels. A test plan for propellant compatibility and extended life tests is included.

Chemistry of Hot Spring Pool Waters in Calamba and Los Banos and Potential Effect on the Water Quality of Laguna De Bay

NASA Astrophysics Data System (ADS)

Balangue, M. I. R. D.; Pena, M. A. Z.; Siringan, F. P.; Jago-on, K. A. B.; Lloren, R. B.; Taniguchi, M.

2014-12-01

Since the Spanish Period (1600s), natural hot spring waters have been harnessed for balneological purposes in the municipalities of Calamba and Los Banos, Laguna, south of Metro Manila. There are at more than a hundred hot spring resorts in Brgy. Pansol, Calamba and Tadlac, Los Banos. These two areas are found at the northern flanks of Mt. Makiling facing Laguna de Bay. This study aims to provide some insights on the physical and chemical characteristics of hot spring resorts and the possible impact on the lake water quality resulting from the disposal of used water. Initial ocular survey of the resorts showed that temperature of the pool water ranges from ambient (>300C) to as high as 500C with an average pool size of 80m3. Water samples were collected from a natural hot spring and pumped well in Los Banos and another pumped well in Pansol to determine the chemistry. The field pH ranges from 6.65 to 6.87 (Pansol springs). Cation analysis revealed that the thermal waters belonged to the Na-K-Cl-HCO3 type with some trace amount of heavy metals. Methods for waste water disposal are either by direct discharge down the drain of the pool or by discharge in the public road canal. Both methods will dump the waste water directly into Laguna de Bay. Taking in consideration the large volume of waste water used especially during the peak season, the effect on the lake water quality would be significant. It is therefore imperative for the environmental authorities in Laguna to regulate and monitor the chemistry of discharges from the pool to protect both the lake water as well as groundwater quality.

Spring Hydrology Determines Summer Net Carbon Uptake in Northern Ecosystems

NASA Technical Reports Server (NTRS)

Yi, Yonghong; Kimball, John; Reichle, Rolf H.

2014-01-01

Increased photosynthetic activity and enhanced seasonal CO2 exchange of northern ecosystems have been observed from a variety of sources including satellite vegetation indices (such as the Normalized Difference Vegetation Index; NDVI) and atmospheric CO2 measurements. Most of these changes have been attributed to strong warming trends in the northern high latitudes (greater than or equal to 50N). Here we analyze the interannual variation of summer net carbon uptake derived from atmospheric CO2 measurements and satellite NDVI in relation to surface meteorology from regional observational records. We find that increases in spring precipitation and snow pack promote summer net carbon uptake of northern ecosystems independent of air temperature effects. However, satellite NDVI measurements still show an overall benefit of summer photosynthetic activity from regional warming and limited impact of spring precipitation. This discrepancy is attributed to a similar response of photosynthesis and respiration to warming and thus reduced sensitivity of net ecosystem carbon uptake to temperature. Further analysis of boreal tower eddy covariance CO2 flux measurements indicates that summer net carbon uptake is positively correlated with early growing-season surface soil moisture, which is also strongly affected by spring precipitation and snow pack based on analysis of satellite soil moisture retrievals. This is attributed to strong regulation of spring hydrology on soil respiration in relatively wet boreal and arctic ecosystems. These results document the important role of spring hydrology in determining summer net carbon uptake and contrast with prevailing assumptions of dominant cold temperature limitations to high-latitude ecosystems. Our results indicate potentially stronger coupling of boreal/arctic water and carbon cycles with continued regional warming trends.

Influence of season of birth on growth and reproductive development of Brahman bulls.

PubMed

Tatman, Shawn R; Neuendorff, Don A; Wilson, Timothy W; Randel, Ronald D

2004-07-01

Seasonal effects on reproduction are more dramatic in Bos indicus than Bos taurus cattle. This experiment evaluated reproductive development of fall- (n=7) versus spring- (n = 10) born Brahman bulls to determine if season of birth affects reproductive development. Measurements of growth and reproductive development began after weaning and continued at bi-weekly intervals until each bull reached sexual maturity. Different stages of sexual development were classified according to characteristics of the ejaculate and included first sperm in the ejaculate, puberty (> 50 x 10(6) sperm/ejaculate), and sexual maturity (two ejaculates with > 500 = 10(6) sperm/ejaculate). Average daily increases in all measured traits were similar in fall- and spring-born bulls and there were no differences in age, body weight, scrotal circumference, or paired testis volume between groups at first sperm or puberty. However, fall-born bulls were older (P < 0.05) than spring-born bulls at sexual maturity (553 days versus 481 days, respectively) as the interval between puberty and sexual maturity was longer (P < 0.05) in fall- than in spring-born bulls (82 days versus 54 days, respectively). The prolonged interval between puberty and sexual maturity in fall-born calves coincided with a short photoperiod (winter) whereas the short interval between puberty and sexual maturity in spring-born calves coincided with a long photoperiod (summer). In conclusion, season of birth affected sexual development; photoperiod might be involved in regulating testicular function immediately after puberty in Brahman bulls.

Tidal variability of nutrients in a coastal coral reef system influenced by groundwater

NASA Astrophysics Data System (ADS)

Wang, Guizhi; Wang, Shuling; Wang, Zhangyong; Jing, Wenping; Xu, Yi; Zhang, Zhouling; Tan, Ehui; Dai, Minhan

2018-02-01

To investigate variation in nitrite, nitrate, phosphate, and silicate in a spring-neap tide in a coral reef system influenced by groundwater discharge, we carried out a time-series observation of these nutrients and 228Ra, a tracer of groundwater discharge, in the Luhuitou fringing reef at Sanya Bay in the South China Sea. The maximum 228Ra, 45.3 dpm 100 L-1, appeared at low tide and the minimum, 14.0 dpm 100 L-1, appeared during a flood tide in the spring tide. The activity of 228Ra was significantly correlated with water depth and salinity in the spring-neap tide, reflecting the tidal-pumping feature of groundwater discharge. Concentrations of all nutrients exhibited strong diurnal variation, with a maximum in the amplitude of the diel change for nitrite, nitrate, phosphate, and silicate in the spring tide of 0.46, 1.54, 0.12, and 2.68 µM, respectively. Nitrate and phosphate were negatively correlated with water depth during the spring tide but showed no correlation during the neap tide. Nitrite was positively correlated with water depth in the spring and neap tide due to mixing of nitrite-depleted groundwater and nitrite-rich offshore seawater. They were also significantly correlated with salinity (R2 ≥ 0.9 and P < 0.05) at the ebb flow of the spring tide, negative for nitrate and phosphate and positive for nitrite, indicating the mixing of nitrite-depleted, nitrate- and phosphate-rich less saline groundwater and nitrite-rich, nitrate- and phosphate-depleted saline offshore seawater. We quantified variation in oxidized nitrogen (NOx) and phosphate contributed by biological processes based on deviations from mixing lines of these nutrients. During both the spring and neap tide biologically contributed NOx and phosphate were significantly correlated with regression slopes of 4.60 (R2 = 0.16) in the spring tide and 13.4 (R2 = 0.75) in the neap tide, similar to the composition of these nutrients in the water column, 5.43 (R2 = 0.27) and 14.2 (R2 = 0.76), respectively. This similarity indicates that the composition of nutrients in the water column of the reef system was closely related with biological processes during both tidal periods, but the biological influence appeared to be less dominant, as inferred from the less significant correlations (R2 = 0.16) during the spring tide when groundwater discharge was more prominent. Thus, the variability of nutrients in the coral reef system was regulated mainly by biological uptake and release in a spring-neap tide and impacted by mixing of tidally driven groundwater and offshore seawater during spring tide.

Circuit Regulates Speed Of dc Motor

NASA Technical Reports Server (NTRS)

Weaver, Charles; Padden, Robin; Brown, Floyd A., Jr.

1990-01-01

Driving circuit regulates speed of small dc permanent-magnet motor in tape recorder. Two nested feedback loops maintain speed within 1 percent of constant value. Inner loop provides coarse regulation, while outer loop removes most of variation in speed that remains in the presence of regulation by the inner loop. Compares speed of motor with commanded speed and adjusts current supplied to motor accordingly.

System analysis of force feedback microscopy

NASA Astrophysics Data System (ADS)

Rodrigues, Mario S.; Costa, Luca; Chevrier, Joël; Comin, Fabio

2014-02-01

It was shown recently that the Force Feedback Microscope (FFM) can avoid the jump-to-contact in Atomic force Microscopy even when the cantilevers used are very soft, thus increasing force resolution. In this letter, we explore theoretical aspects of the associated real time control of the tip position. We take into account lever parameters such as the lever characteristics in its environment, spring constant, mass, dissipation coefficient, and the operating conditions such as controller gains and interaction force. We show how the controller parameters are determined so that the FFM functions at its best and estimate the bandwidth of the system under these conditions.

High-Q enhancement of attractive and repulsive optical forces between coupled whispering-gallery- mode resonators.

PubMed

Povinelli, Michelle; Johnson, Steven; Lonèar, Marko; Ibanescu, Mihai; Smythe, Elizabeth; Capasso, Federico; Joannopoulos, J

2005-10-03

We have calculated the optically-induced force between coupled high-Q whispering gallery modes of microsphere resonators. Attractive and repulsive forces are found, depending whether the bi-sphere mode is symmetric or antisymmetric. The magnitude of the force is linearly proportional to the total power in the spheres and consequently linearly enhanced by Q. Forces on the order of 100 nN are found for Q=108, large enough to cause displacements in the range of 1mum when the sphere is attached to a fiber stem with spring constant 0.004 N/m.

Analysis of Piston Slap Motion

NASA Astrophysics Data System (ADS)

Narayan, S.

2015-05-01

Piston slap is the major force contibuting towards noise levels in combustion engines.This type of noise depends upon a number of factors such as the piston-liner gap, type of lubricant used, number of piston pins as well as geometry of the piston. In this work the lateral and rotary motion of the piston in the gap between the cylinder liner and piston has been analyzed. A model that can predict the forces and response of the engine block due to slap has been dicussed. The parameters such as mass, spring and damping constant have been predicted using a vibrational mobility model.

Spatial Light Modulators and Applications: Summaries of Papers Presented at the Spatial Light Modulators and Applications Topical Meeting Held on March 15-17, 1993 in Palm Springs, California

DTIC Science & Technology

1993-03-17

modulator: Number of Elements 16 x 16 Pixel Size 1 mmxl mm Area Fill Factor > 90% Reflectance > 90% Phase Shift 900 Frame Rate > 1 kHz Operational Spectral...electro-optic constants. By using reflected light from the second interface a factor of two increase in phase shift is obtained for an applied voltage vs...wavelengths in general require thinner PLZT wafers. One of the objectives of the SLM design was to maximize pixel area fill factor and thereby the

Exogenous application of molybdenum affects the expression of CBF14 and the development of frost tolerance in wheat.

PubMed

Al-Issawi, Mohammed; Rihan, Hail Z; Woldie, Wondwossen Abate; Burchett, Stephen; Fuller, Michael P

2013-02-01

Wheat is able to cold acclimate in response to low temperatures and thereby increase its frost tolerance and the extent of this acclimation is greater in winter genotypes compared to spring genotypes. Such up-regulation of frost tolerance is controlled by Cbf transcription factors. Molybdenum (Mo) application has been shown to enhance frost tolerance of wheat and this study aimed to investigate the effect of Mo on the development of frost tolerance in winter and spring wheat. Results showed that Mo treatment increased the expression of Cbf14 in wheat under non-acclimating condition but did not alter frost tolerance. However, when Mo was applied in conjunction with exposure of plants to low temperature, Mo increased the expression of Cbf14 and enhanced frost tolerance in both spring and winter genotypes but the effect was more pronounced in the winter genotype. It was concluded that the application of Mo could be useful in situations where enhanced frost resistance is required. Further studies are proposed to elucidate the effect of exogenous of applications of Mo on frost resistance in spring and winter wheat at different growth stages. Crown Copyright © 2012. Published by Elsevier Masson SAS. All rights reserved.

Effect of the Winter Wheat Cheyenne 5A Substituted Chromosome on Dynamics of Abscisic Acid and Cytokinins in Freezing-Sensitive Chinese Spring Genetic Background

PubMed Central

Kalapos, Balázs; Novák, Aliz; Dobrev, Petre; Vítámvás, Pavel; Marincs, Ferenc; Galiba, Gábor; Vanková, Radomira

2017-01-01

The effect of short- and long-term cold treatment on the abscisic acid (ABA) and cytokinin (CK) metabolism, and their main biosynthesis- and signaling-related genes were investigated in freezing-sensitive and freezing-tolerant wheat genotypes. Varieties Cheyenne and Chinese Spring substituted with the 5A Cheyenne chromosome, which represented freezing-tolerant genotypes, were compared with the freezing-sensitive Chinese Spring. Hormone levels and gene expression data indicated that the short- and long-term cold treatments are associated with specific regulation of the accumulation of cold-protective proteins and phytohormone levels, as well as the expression profiles of the hormone-related genes. The significant differences were observed between the genotypes, and between their leaf and crown tissues, too. The level of dehydrins, including WCS120 protein, and expression of WCS120 gene were considerably higher in the freezing-tolerant genotypes after 21 days of cold treatment. Expression of Cor14b and CBF14, cold-responsive regulator genes, was increased by cold treatment in all genotypes, to higher extent in freezing-tolerant genotypes. Cluster analysis revealed that the tolerant genotypes had a similar response to cold treatment, regarding expression of the ABA and CK metabolic genes, as well as hormone levels in leaves. As far as hormone levels in crowns are concerned, however, the strongly freezing-tolerant Cheyenne variety clustered separately from the Chinese Spring and the substitution line, which were more similar to each other after both 1 and 21 days of cold treatment than to Cheyenne. Based on these results we concluded that the 5A chromosome of wheat might have both a direct and an indirect impact on the phytohormone-dependent cold-induced freezing tolerance. Based on the gene expression data, novel genetic markers could be developed, which may be used to determine the freezing tolerance level in a wide range of wheat varieties. PMID:29238355

21 CFR 1250.42 - Water systems; constant temperature bottles.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Water systems; constant temperature bottles. 1250.42 Section 1250.42 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) REGULATIONS UNDER CERTAIN OTHER ACTS ADMINISTERED BY THE FOOD AND DRUG ADMINISTRATION...