Simultaneous Pumping Research Articles

Sequential and simultaneous breast pumping: a comparison

This study compared sequential single-breast pumping with simultaneous double-breast pumping using an interrupted time series design to determine if (a) milk volume differed by pumping regimen; (b) the time needed to pump the breasts differed by pumping regimen; and (c) the milk fat concentrations differed by pumping regimen. In both limited and unlimited pumping sessions, the simultaneous double pumping option obtained higher mean milk volumes, reaching statistical significance in three of the four comparisons. Differences in milk fat concentrations were not statistically significant, when simultaneous breast pumping occurred, as compared with sequential pumping. Mothers' preferences regarding pumping regimen influenced mean milk volumes obtained in the direction of the women's preferences.

Production of full intensity, highly nuclear spin polarized alkali-metal ( 23Na) beams by a double resonance technique

Simultaneous optical pumping with a laser and induction of rf transitions within the hyperfine levels of alkali-metal ( 23Na) ground states allow to pump all atoms of an atomic beam into one hyperfine component ( F = 2, m F = +2 or −2). The technique used is briefly described. The effect of coherent coupling between atomic states (Autler-Townes or dynamical Stark effect) is discussed in some detail, in particular how to avoid drawbacks of this effect on the optical pumping process.

A simple theoretical model of steady-state electrogenic transfer of reactive species across membranes

Transfer across membranes is treated for simultaneous active pumping and passive flow of the main ionic constituents of plant cells. The chemical equilibrium conditions for H2CO3 and H2O dissociation prevailing in the external and internal solutions are taken into account. Our model assumes steady-state conditions, zero electrical current, electroneutrality inside the membrane and, in both solutions, finite space charge densities in two diffuse regions in contact with both sides of the membrane. A computer program has been developed for the integration of a set of flux equations. The results are displayed in terms of ionic flux parameters, each proportional to the ionic pump flow and to the reciprocal of the passive ionic mobility. The discussion emphasizes the role of anion inward pumping and of non-diffusible anions. The cationic pumps serve to establish different ionic balances in the cell. Transmembrane (bulk to bulk) proton pumping affects essentially the pH regulation in the cell.

Modeling Two‐Well System in a Stratified Aquifer

A mathematical model and computational methods were developed for the flow behavior analysis of a stratified aquifer in response to simultaneous pumping of two fluids from both sides of the interface. A typical application may be found in coastal aquifers for suppressing the salinity upconing often encountered by the single well pumping. Using two numerical methods, the boundary element method and the finite element method, two‐dimensional steady state conditions were simulated for the two‐well system. The computed results were compared with bench scale experiments and the Dupuit approximation theory.

Simulation of Two‐Fluid Response in Vicinity of Recovery Wells

A dense fluid in an unconfined aquifer is usually removed by pumping a recovery well screened in the region of the aquifer occupied by the fluid. For many problems, the transition zone separating the dense fluid from the overlying water can be modeled as a sharp interface. When pumping begins, the interface is drawn downward, allowing water to enter the well. The recovery process is improved if a second well is drilled and screened in the zone occupied by the water. The simultaneous pumping of water tends to cause the interface to move upward, allowing the dense fluid to be recovered at an increased rate without water entering the recovery well. The boundary integral equation method (BIEM) is used to solve the problem of the response of a dense fluid near a recovery well in a ground‐water aquifer. The axisymmetric problems considered here are time‐dependent and involve a nonlinear boundary condition along the free surface, as well as a nonlinear, moving interfacial boundary. The entire boundary, including the moving boundaries, are discretized into axisymmetric finite elements for evaluating the required boundary integrations. Numerical examples include pumping both fluids simultaneously as well as separately. The model is used to illustrate the design of a recovery system for the efficient removal of the dense fluid.

Coupled laser-induced fluorescence series (CLIFS) in 7Li 2

In this letter we demonstrate the enhancement of a fluorescence series by simultaneous pumping of a second coupled series at the same frequency. Using a Kr + laser (568.2 nm) and 7Li 2 molecules, we have observed four fluorescence series and enhanced emission from B 1 Π u ( v′ = 9, J′ = 25). This enhancement results from the coupling of an A-X series and a B-X series through the level X 1 σ + g ( v″ = 16, J″ = 25). This level is populated primarily through the A-X fluorescence and at the same time is the lower level for the excitation of the B-X series.

Observation of direct infrared multiphoton pumping of the triplet manifold of biacetyl

Direct collisionless multiphoton (MP) excitation of the triplet vibronic manifold of biacetyl is reported. Following a dye laser pulse which prepares some of the biacetyl molecules in the triplet metastable state, the system is irradiated by an intense 20 ns 9.6μ CO2 pulse. The CO2 radiation induces fast quenching of the phosphorescence emission from the 3Au excited molecules. It also induces an emission signal in the fluorescence spectral region of biacetyl. This signal is related to an inverse electronic relaxation (IER) from excited triplet vibronic levels into isoenergetic singlet 1Au vibronic levels. Analysis of the induced luminescence signals provides information on the collisionless MP prompted vibrational distribution. Excitation with 10.6μ CO2 pulses leads to the simultaneous MP pumping of both the ground and triplet manifolds. The generation of blue emission signals in this experiment bears a close resemblance to recent observations of prompt visible emission due to MP pumping of ground state molecules. General expressions for the emission intensities are derived with special emphasis on the specific features of MP vibrational distributions. The detectability of MP induced emission signals is discussed.

Atrial Pacing during Intraaortic Balloon Pumping

Intraaortic balloon pumping and atrial pacing are both useful in treating postoperative low output syndrome. However, the electrocardiographic atrial pacing spike can interfere with the electrocardiogram tracking mechanism of many balloon consoles. Bipolar epicardial pacing can avoid this problem and allow simultaneous atrial pacing and intraaortic balloon pumping.

Dual-frequency optical pumping for spin-polarizing a lithium atomic beam

A lithium-6 atomic beam is spin-polarized by means of optical pumping with a single-mode dye laser operating on the resonance transition. Simultaneous pumping of both hyperfine substates is achieved by frequency-splitting the laser light with an acousto-optic modulator. A polarization dependent signal, obtained by probing the optical activity of the beam with linearly polarized light, is utilized in a microprocessor-controlled laser stabilization scheme. The polarization is analyzed with a sextupole magnet and its overall value is 0.70 for an intensity of 1×1014 atms s−1. By reversing the sense of circular polarization of the pumping light the atomic beam polarization is easily reversed in direction.

A double-channel nitrogen laser

A compact double-channel nitrogen laser which permits the simultaneous pumping of two dye lasers, or a dye laser oscillator and a dye amplifier, is described. The characteristics of each emitted pulse are typically 200 kW and 5 ns.

Capillary isotachophoresis: continuous sampling technique in the analyses of low-concentration samples

A method has been developed for sampling that permits an increase in the total amounts of sample components in an isotachophoretic system so that the zones which originate can be detected and evaluated. This method is based on the simultaneous pumping of the leading electrolyte and the sample in an isotachophoretic column. It is shown that the continuous sampling technique is quantitative and that it increases the operational capability of isotachophoresis at least by 1/2-2 orders of magnitude towards lower concentrations. As an illustration, the simultaneous analysis of chlorides and sulphates in a mineral water is reported and the results are compared with those of titrimetric, gravimetric and previous isotachophoresis analyses.

Spatial hole burning and oligo-mode distance control in CW dye lasers

Spatial hole burning at the position of the dye cell is identified to be responsible for stable double-, triple-, and higher oligo-mode action in a narrow-band CW dye laser. This may be exploited systematically to control the mode distances by arranging the positions of both resonator end mirrors. A total output power up to over 100 mW is obtainable for double- or triple-mode action. Special conditions are described to obtain stable double-mode action with 1772-MHz mode spacing, as needed for simultaneous optical pumping of the two sodium hyperfine ground states.

Simultaneous pumping of fresh and salt water from a coastal aquifer

When fresh water is pumped from an aquifer which is open to a recharging salt-water body, care must be taken to avoid the encroachment of salt water into the well. A measure which sometimes may be taken when there is also a demand for filtered salt water is to supplement the fresh-water well by a salt-water well, located between the fresh-water well and the coast, and to pump both wells at comparable rates. This paper analyzes the idealized case where the aquifer is confined, thin, homogeneous and isotropic, semi-infinite in areal extent, and bounded on one side by a straight recharge boundary; it is furthermore assumed that the nonpumping piezometric surface of the aquifer has a steady, uniform slope towards the boundary. As a result of the analysis a relation is established between the distances from each of the wells to the boundary, the ratio between the pumping rates of the two wells, and the maximum pumping rate at which no salt water is induced into the fresh-water well; this relation can be used in the selection of the optimum location of the pair of wells.

Measurement of V-V transfer rate from HF v = 3 using simultaneous optical pumping on the HF v = 2 → 1 and v = 1 → 0 bands

A measurement of the (predominantly) vibration-vibration (V-V) decay rate of the v = 3 level in HF gas yields a value of 1.6×106 sec−1 Torr−1. The technique utilized was to optically pump the HF sample with the output of a pulsed HF laser oscillating simultaneously on a line in both the v = 2 → 1 and v = 1 → 0 bands. An analytic description of the time behavior of the v = 1, v = 2, and v = 3 levels using a treatment based on simplified rate equations is described.

Extending the Tuning Range of Tunable Oscillators by Upconversion

The operation of a doubly resonant LiIO3 parametric oscillator is described. Simultaneous pumping of this oscillator and a LiIO3 upconverter by a single ruby-laser beam was employed to extend the tuning range of the parametric oscillator down to the 4200–5100-Å range. Up to 10 kW of upconverted power with a 1-MW ruby-laser pump was observed; with an intracavity upconverter, a substantial increase in the over-all efficiency should be achievable.

Diffusion across a Semiconductor-Vapour Interface

General boundary conditions associated with diffusion across a solid - vapour interface are considered in detail and the diffusion equation is solved subject to these boundary conditions. Analytic solutions are derived for: (a) diffusion outwards of an impurity into a finite volume with or without simultaneous pumping; (b) diffusion inwards from a limited source of impurity, initially in the vapour phase, in a closed system. These results are discussed with reference to the diffusion of Group III and V elements across germanium and silicon surfaces.