Time markers

The Time Marker bar with associated Time Markers at the bottom of the timeline. 

To add a Time marker, position the timeline cursor at the location where you want to drop a marker. Then, from the Insert menu, select Time Marker. You can also press the H key as a keyboard shortcut. 

As with other kinds of markers, you can rename and delete Time markers by right-clicking them to access the context menu. Time markers can be dragged to a new location and can be used for navigational purposes as well (again from the context menu). 

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Deciphering the cause(s) of the Late Wisconsin dust interval will be the subject of many future studies, but the interval serves as a useful time marker at present. Koerner and Fisher [34] have used elevated microparticle concentrations in the Devon Island ice core as an indicator of Wisconsin-aged ice. Similarly high continental dust concentrations are expected in the recently recovered cores from the East Antarctic plateau. 

Other events, evidence of which has not yet been detected in polar ice, may also eventually serve as useful time markers in the future. Large meteors or meteor swarms that ablated in the upper atmosphere may have left a significant chemical impact on succeeding snowfalls. The same may be true for cometary collisions or brushes with a comet s tail. As with ancient volcanic eruptions, such events need not have been historically documented. If identified and accurately dated in one ice core, these events will serve as useful time horizons in other cores. 

Glaciochemical horizons not only provide checks on depth-age relationships but are of great intrinsic interest. Continuous chemical analysis of a well-dated core promises to greatly extend and refine the record of explosive volcanism [13]. Each well-dated eruption or other horizon then becomes of use as a time marker for cores where the dating is less precise. 

The lung volume level for measurement of MEF40% and MEF40%(P) is shown by the dashed vertical line. Point of maximum inspiration is indicated by the zero point on volume axis. The v shaped pen deflection near full expiration on MEFV curve is the one second time marker for measurement of FEV, . The entire expiration-inspiration-expiration maneuver was recorded uninterrupted. 

Fig. 4 Depth-age relationship of the ice cores from Fiescherhom glacier [12] and Colle Gnifetti [13, 14], Besides annual layer counting and radiocarbon ( C) dating, two types of time markers were used Saharan dust events (labeled by the year only) and volcanic eruptions (labeled by year and name of volcano). Depth is given in water equivalent. This is the amount of water contained in the ice core which is calculated using fim and ice density, respectively, both increasing with depth...

C-values of limestones vary mostly within a band of 0 3%c since at least 3.5 Ga (Veizer and Hoefs 1976). The longer term C-isotope trend for carbonates has be punctuated by sudden shifts over short time intervals named carbon isotope events , which are considered to represent characteristic features, and have been used as time markers for stratigraphic correlations. 

Coupling a screening system with an analytical fraction collector can be helpful when very small amounts (submilligrams to single-digit milligrams) are required. It often also provides the first opportunity to isolate enriched samples for further use in the method development, for example, as retention time markers. The choice of stationary phases in the method development system can be based on... 

Oumada, R Z., Roses, M., and Bosch, E. Inorganic salts as hold-up time markers in C18 columns, Talanta, 53(3), 667-677, 2000. 

I. Sampling and Flow. In the absence of a timing marker on the record, it is possible to provide a visual reference of the division between... 

The TAC/MCPHA combination must be calibrated to give the time interval per channel. This can be achieved in a number of different ways [47] and is a particularly simple process if a mode-locked laser is used as the excitation source. Since the mode-locker frequency should be stable and well known, then the spacing between laser pulses is also well defined. By scattering the laser pulses so that they can be detected by the photon counting system, accurate time markers can be obtained. 

Figure 10 Effect of buffer concentration and temperature on EOF in CEC. Column CEC-Hypersil C18, 3 pm, 250 (350) X 0.1 mm mobile phase 80% acetonitrile/ Tris-HCI, pH 8, buffer concentration and temperature given in the figure voltage, 20 kV dead-time marker, thiourea. (Reprinted with permission from Ref. 47, copyright 1997, Wiley.)...

Signals in most if not all positron experiments are transmitted along coaxial cables in the form of current pulses—i.e., a charge dq in time dr, where dr is in the range lO -lO3 ns. The pulses are used for counting, to locate events, to measure energy, as time markers, and so on. 

Scientific, Darien, IL). Five compounds—ascorbic acid (dead time marker), hydroquinone, resorcinol, catechol, and 4-methyl catechol—were eluted with a 10/90 (v/v) acetonitrile/water mobile phase containing 0.1 % TFA and were detected with amperometric detection (+1.0V versus Ag/AgCl). The chromatogram was obtained near the optimum linear velocity at a run pressure of 3000 bar. All compounds eluted in less than 8 minutes, with efficiencies ranging from a low of 244,000 plates for 4-methyl catechol to as high as 330,000 plates for hydroquinone. These correspond to about 570,000 and 770,000 plates/m, respectively—much higher than the 150,000 plates/m typically seen with conventional columns. 

Fig.4 Concentration dependence of the ratio of relaxatitm time (markers) and the ratio of viscosity (solid curves).

Time-markers for tying short-lived chronometers to an absolute timescale can potentially be provided by early planetary differentiates. The basic requirements are that appropriately ancient samples would have to have evolved from a reservoir (magma) that had achieved isotopic equilibrium with respect to daughter elements of... 

Skelton A., Annersten H., and Valley J. (2002) and yttrium zoning in garnet time markers for fluid flow ... 

Robertson, D.S., Basel Proterozoic units as fossil time markers and their use in uranium prospection in formation of uranium ore deposits, pp. 495-512. Proceedings of a Symposium, Athens, Inti. Atom. Energy Agency, Vienna, 1974. 

Coincident with this new technique for procurement of human bone biopsies was the development of quantitive methods of bone analysis.12 These methods include histochemical analysis of both decalcified and unde-calcified42 48 bone sections, microradiography,44 tetracycline labeling45 and autoradiography.42 The latter two techniques require administration of a tetracycline antibiotic or isotopic tracer prior to procurement of the biopsy. Undecalcified thin sections, prepared with the use of a Jung microtome after the bone core is fixed, dehydrated and embedded in methacrylate,45 are analyzed by intersect and point count methods46 47 which permit three-dimensional assessment.48 49 Tetracycline antibiotics deposit in vivo in sites of bone formation constituting markers which can be studied in undecalcified sections by fluorescence microscopy.45 47 This represents the safest and best tissue time marker for microscopic measurement of bone formation dynamics. 

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