Population control

The ability to create and observe coherent dynamics in heterostructures offers the intriguing possibility to control the dynamics of the charge carriers. Recent experiments have shown that control in such systems is indeed possible. For example, phase-locked laser pulses can be used to coherently amplify or suppress THz radiation in a coupled quantum well [5]. The direction of a photocurrent can be controlled by exciting a structure with a laser field and its second harmonic, and then varying the phase difference between the two fields [8,9]. Phase-locked pulses tuned to excitonic resonances allow population control and coherent destruction of heavy hole wave packets [10]. Complex filters can be designed to enhance specific characteristics of the THz emission [11,12]. These experiments are impressive demonstrations of the ability to control the microscopic and macroscopic dynamics of solid-state systems. 

In an early study in 1971, Cole22 found an association between coffee drinking and lower urinary tract cancer based on a case-control study of 445 cancer patients (345 men, 100 women) and 451 population controls who were matched for age and sex. The analyses had controlled for cigarette smoking and occupation however, there was no consistent dose response relation, and the summary risks were significant only in women,... 

Defect populations and physical properties such as electronic conductivity can be altered and controlled by manipulation of the surrounding atmosphere. To specify the exact electronic conductivity of such a material, it is necessary to specify its chemical composition, the defect types and populations present, the temperature of the crystal, and the surrounding partial pressures of all the constituents. Brouwer diagrams display the defect concentrations present in a solid as a function of the partial pressure of one of the components. Because the defect populations control such properties as electronic and ionic conductivity, it is generally easy to determine how these vary as the partial pressure varies. 

Presently we observe the ideologisation of the discussion of practically all ecological and social problems, be it population control, migration, multicultural coexistence,... 

Significant ethnic variability is observed with many pharmacogenetic markers (38). Consequently, the demographics of the study population need to be taken into account when performing power analyses to determine the appropriate sample size. If the frequency of the polymorphism to be studied is unknown in any of the ethnic groups included in the study, the polymorphism should be screened in relevant population controls to determine their allele frequency. This will help to narrow down the number of polymorphisms to be included and prevent using finite patient DNA to assess markers that may have low frequency or be absent from the study population. 

GM Geometric mean 5th Percentile NSth Percentile Exposed populations Control populations... 

In an abstract, Freudenheim et al. (1997) presented the results of a study conducted in western New York, United States, on 134 premenopausal and 181 postmenopausal cases of breast cancer and 356 population controls. Heavy alcohol intake was associated with an increased risk for premenopausal breast cancer (odds ratio, 3.5 95% CI, 1.3-9.2) among ADHj subjects but not among women with ADHj or ADH32-2 genotypes. This association was not observed for postmenopausal breast cancer. 

Using data collected in the population-based case-control study of cancer among male residents of Montreal, Canada, described in the monograph on dichloromethane (see this volume), Gerin et al. (1998) carried out an analysis focusing on cancer risks in relation to benzene, toluene, xylene (see this volume) and styrene exposure. For these analyses, the control group for each case series consisted of a combination of the 533 population controls with 533 cancer controls selected at random from the pool of eligible cancer controls. Fifteen per cent of the entire study population had been exposed to toluene at... 

Quantum control beyond spectral interference and population control Can resonant intense laser pulses freeze the population ... 

In this contribution recent results [13] on the control of the quantum mechanical phase of an atomic state in strong laser fields studied using the Autler-Townes (AT) effect [14] in the photoionization of the K (4p) state are discussed. We demonstrate quantum control beyond (i) population control and (ii) spectral interference, (i) We show, that for suitable combinations of the laser intensity of the first pulse and the time delay the second resonant intense laser pulse leaves the excited state population unchanged. However, the knowledge of the... 

We demonstrate coherent control in strong fields beyond (i) population control and (ii) spectral interference, since (i) control is achieved without altering the population during the second intense laser pulse, i.e., the population during the second laser pulse is frozen, and (ii) the quantum mechanical phase is controlled without changing the spectrum of the pulse sequence. The control mechanism relies on the interplay of the quantum mechanical phase set by the intensity of the first pulse and the phase of the second pulse determined by the time delay. 

What can be done to prevent atherosclerosis For persons with a high LDL level there is little doubt that a decreased dietary intake of cholesterol and a decrease in caloric intake are helpful. While such dietary restriction may be beneficial to the entire population, controlled studies of the effect of dietary modification on atherosclerosis have been disappointing and confusing.33 A diet that is unhealthy for some may be healthy for others. For example, an 88-year old man who ate 25 eggs a day for many years had a normal plasma cholesterol level of 150-200 mg / deciliter (3.9-5.2 mM) bb Comparisons of diets rich in unsaturated fatty acids, palmitic acid, or stearic acid have also been confusing.cc cd/dd Can it be true that palmitic acid from tropical oils and other plant sources promotes atherogenesis, but that both unsaturated fatty acids and stearic acid from animal fats are less dangerous ... 

Dose is an important factor, but these adverse effects have been described after low doses. The risk of hip fracture associated with glucocorticoid use has been studied in Denmark in a population-based case-control study in 6660 subjects with hip fractures and 33 272 age-matched population controls (215). Data on prescriptions for glucocorticoid within the last 5 years before the index date were retrieved from a population-based prescription database. Doses were recalculated to prednisolone... 

Integrating mating disruption techniques with microbial or chemical pesticides may prove efficacious. Epidemics could be suppressed with the pesticide, with the disruption technique being aimed at preventing reproduction in peripheral areas, keeping the population at low levels. The male annihilation concept, although yet to be proven in the field, offers another approach to population control. 

The use of nuclear family data in association studies was initially developed to avoid possible ethnic mismatching between patients and randomly ascertained controls (76). The parental marker alleles not transmitted to an affected child, or never transmitted to an affected sib pair, form the so-called AFBAC population (19,20) (Fig. 1). In a random mating population, when there is a marker association with disease, the AFBAC population provides an unbiased estimate of the overall population (control) marker alleles when the recombination fraction between the marker and disease genes is sufficiently small that it can be taken as zero (0 = 0), and differences between patient and AFBAC frequencies can be tested for example by a contingency table analysis for heterogeneity. 

A fundamental limitation to coherent population control is that it is impossible to transfer 100% of the population in a mixed state. That is, the maximum value of the population transferred cannot exceed the maximum of the initial population distribution of a system without any dissipative process such as spontaneous emission. This result can be simply verified using the unitary property of the density operator, pit) = U(t, to)pito)U t, to), where p(to) is the diagonalized density operator at t = to, Uit, to) is the time-evolution operator given by... 

We elected to study coherent up-pumping dynamics in solution-phase metal-hexacarbonyl systems because of their strong vibrational infrared absorption cross sections, relatively simple ground-state spectra, and small (ca. 15 cm ) anharmonic overtone shifts. It was felt that these systems are ideal candidates to demonstrate that population control could be achieved for polyatomic species in solution because the excited state population... 

As indicated earlier H. subflexa has recently become the subject of numerous pest control studies due to the potential for population control of H. virescens by a sterile hybrid release program. However, these two species maintain reproductive isolation despite broadly overlapping ranges and intersecting reproductive periods. Hence, barriers to interspecific gene flow are most likely due to differences in their respective sex pheromone communication systems and, as indicated earlier, there are considerable differences in the pheromone gland contents of each. 

---