Monitoring Population Changes

Some laboratory personnel elect to follow the progress of starter cultures as a function of MLF and, therefore, utilize paper chromatographic separation (detecting changes from malate to lactate) as they would normally use in monitoring MLF in wine. However, conversion of malic to lactic acid does not necessarily correspond to population increases resulting from utilization of fermentable sugars hence, the technique may not be a valid indicator. 

Inoculation into the main volume of fermentation or wine should correspond to stationary-phase growth. This is the point at which the culture is relatively immune (compared with younger cells) to the activity of bacteriophage. In the case of Leuc, oenos, stationary-phase growth is microscopically visualized by the presence of LAB in often twisted chains of 5 cells (see Fig. 1-3). 

At the end of the incubation period, starter cell titer should be near 10 CFU/mL. Assuming one wished to inoculate at a level of 10 CFU/mL (or a 100-fold dilution), 10 gal of prepared starter is sufficient to inoculate 1000 gal of wine or fermenting juice. 

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Fig. 12. Experimental measurement of multiphonon up-pumping in nitromethane (NM), reproduced from ref. [127]. Phonons are generated using a picosecond pulse to excite a dye molecular heater. Anti-Stokes Raman spectroscopy is used to monitor population changes that can be converted to vibrational quasitemperatures. The 657 cm 1 doorway vibration is pumped faster than the instrument resolution of 25 ps. The 918 cm C-N stretch, which must be activated to break a C-N bond, is excited 25 ps later.

The third kind of assessment was hazard testing conducted in the field either by using domesticated non-Apis bees maintained in artificial domiciles or by monitoring native populations in their natural habitat. The drawback of these methods is that standardization is not possible since the exposure of experimental insects to test compounds is not controlled. In the case of native population monitoring, the main difficulty is the interpretation of data due to the number of factors involved in population changes during seasons and years. 

The aim of the present study was to monitor the changes in PSII heterogeneity during exposure of attached leaves to high light at different temperatures and secondly to elucidate the sensitivity of different PSII populations to photoinhibition in vivo ... 

Cocolin, L., M. Manzano, S. Rebecca, and G. CoMi. 2002. Monitoring of yeast population changes during a continuous wine fermentation by molecular methods. Am.J. Enol. Vitic. 53 24-27. 

The possible direct monitoring of the population change of different vibrational levels of relaxing molecules using kinetic spectroscopy will also be mentioned. 

Of wide use are now various kinetic spectroscopic methods which permit to follow the time evolution of the intensity of a particular optical or infrared transition. This provides direct measurements of the relaxation rate constants. Also, the double resonance technique should be mentioned. It uses one laser for the population of a particular vibrational molecular level and another (of a much lower intensity and of a quite different frequency) to monitor the population change of this and the neighbouring levels caused by relaxing transitions. 

During the AF, the LAB population changes drastically, depending on numerous factors (Lonvaud-Funel 2006). At the end of AF, the LAB cell count is about 10 CFU/ml, and then it reaches approximately 10 CFU/ml when the MLF is clearly visible. A few days or even several months can separate the end of the AF and the start of MLF. During this time, the wine must be monitored because yeast... 

The condensed phases also are important to the physical processes of the atmosphere however, their role in climate poses an almost entirely open set of scientific questions. The highest sensitivity of physical processes to atmospheric composition lies within the process of cloud nucleation. In turn, the albedo (or reflectivity for solar light) of clouds is sensitive to the number population and properties of CCN (Twomey, 1977). At this time, it appears impossible to predict how much the temperature of the Earth might be expected to increase (or decrease in some places) due to known changes in the concentrations of gases because aerosol and cloud effects cannot yet be predicted. In addition, since secular trends in the appropriate aerosol properties are not monitored very extensively there is no way to know... 

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