The stellar and solar tracking system of the Geneva Observatory gondola

Sun and star trackers have been added to the latest version of the Geneva Observatory gondola. They perform an image motion compensation with an accuracy of plus or minus 1 minute of arc. The structure is held in the vertical position by gravity; the azimuth is controlled by a torque motor in the suspension bearing using solar or geomagnetic references. The image motion compensation is performed by a flat mirror, located in front of the telescope, controlled by pitch and yaw servo-loops. Offset pointing is possible within the solar disc and in a 3 degree by 3 degree stellar field. A T.V. camera facilitates the star identification and acquisition

Mars low albedo regions: Possible map of near-surface

A freeze/thaw desorption mechanism is proposed in certain low albedo areas which could be the factor that instigated dust storms. It is widely accepted that the bulk of the episodic gas evolution (not necessarily the oxygen release) experienced during the humidification process in the Viking Gas Exhange Experiment (GEX) was caused by a familiar process in which more polar H2O molecules replace large quantities of other preadsorbed gas molecules on adsorption sites. The author suggests that a similar process could produce high pore pressures in soil that could disrupt the soil and eject dust at high velocity. The author also argued that association of sites of dust storms initiated with high thermal inertial areas may simply reflect repeated dust depletion

Photochemical weathering and contemporary volatile loss on Mars

In an earlier series of papers by the author it was proposed that photochemical weathering of Fe(2+) in magnetite and in mafic silicates may be occurring in the contemporary surface environment with a resultant loss of O2 from the atmosphere. Morris and Lauer challenged the photochemical weathering model, proposing that oxidation by radiant heating rather than UV photoelectron emission induced oxidation may have dominated in the authors experiments. Subsequent laboratory studies of photochemical weathering of magnetite described here support the authors original proposal that UV illunimation can indeed drive the oxidation of magnetite under contemporary Martian surface conditions. The negative results of the Morris and Lauer study can now be explained

What Triggers Early Retirement ? Results from Swiss Pension Funds

Early retirement is predominantly considered as the result of incentives set by social security and the tax system. But people seem to retire early even in the absence of such distortions as the Swiss example demonstrates. We look for determinants of early retirement, in particular the role of lifetime income and family status, using individual data from a selection of Swiss pension funds. Our findings suggest that affordability is a key determinant in retirement decisions: More affuent men, and - to a much smaller extent - women, tend to leave the work force earlier. The fact that early retirement has become much more prevalent in the last 15 years is another indicator for the importance of affordability as Switzerland's funded pension system has matured over that period leading to higher effective replacement rates.occupational pension; retirement decision; duration models

Physicians' working practices : target income, altruistic objectives or a maximization problem ?

In traditional literature, a number of authors posit that physicians, like a consumer or a firm, adopt maximization behavior, while others claim that they are motivated by the attainment of a target income. These three approaches may seem contradictory, yet the present study aims to show that they are in fact complementary. This paper aims to highlight the overlapping of these approaches by using a theoretical model - the agent model. From this model, we deduce the income effect, the individualistic substitution effect, the monopolistic effect and their respective elasticities to detect target income behavior. We develop also two theoretical models of leisure and income renouncement to determine the priority which the physician gives to consumption and leisure. Unlike other models, our results show that about 20% of physicians prefer to reach an altruistic objective rather than a leisure or an target income. These last result implies a ranking of target priorities. Moreover, we observe that the Slutsky relation cannot be used to determine individualistic substitution, monopolistic substitution and income effects exactly when leisure is an inferior good. Nor can we confirm the adoption of a target income behavior when income and monopolistic elasticities are negative. Renouncement models indicate that between 60% and 67% of GPs have a clear consumption priority and that they accept a renouncement of their leisure in order to maintain their current level of income. Our results demonstrate that it would be necessary to introduce monopolistic power of physicians and their altruistic priority to test inducement demand.

Chemical frost weathering of olivine: Experimental study and implications

New experimental results are reported on the frost weathering of olivine. After first weathering, a decrease in Fe sup 2(+)M(2) absorption bands were noted. This decrease is related to the protonation of O(+) in the mineral. It is contented that this reaction may result in the regolith storage of 100 to 1000 m of H(sub 2) over the history of Mars

Why Forcing People to Save for Retirement may Backfire

If individuals are unable or unwilling to borrow, a higher than desired second pillar pension capital may induce people to retire earlier than they would have in the absence of such a scheme. Individuals thus leave the workforce as soon as the retirement income is deemed sufficient and the pension plan avails withdrawal of benefits. We provide evidence using individual data from a selection of Swiss pension funds, allowing us to perfectly control for pension scheme details. Our findings suggest that affordability is a key determinant in the retirement decisions. The higher the accumulated pension capital, the earlier individuals tend to leave the workforce.occupational pension, retirement decision, duration models

Why Forcing People to Save Retirement May Backfire

Early retirement is predominantly considered to be the result of incentives set by social security and the tax system. But the Swiss example demonstrates that the incidence of early retirement has dramatically increased even in the absence of institutional changes. We argue that an actuarially fair, but mandatory funded system may also distort optimal individual allocation. If individuals are credit constraint (or just reluctant to borrow), a higher than desired retirement capital induces people to retire earlier than they would have in the absence of such a scheme. Individuals thus retire as soon as the retirement income is deemed sufficient the pension plan avails withdrawal of benefits. We provide evidence using individual data from a selection of Swiss pension funds, allowing us to perfectly control for pension scheme details. Our findings suggest that affordability is indeed a key determinant in the retirement decisions. The fact that early retirement has become much more prevalent in the last 15 years is a strong indicator for the importance of affordability as the maturing the Swiss mandatory funded pension system over that period has led to an increase in the already high effective replacement rates. Moreover, even after controlling for the time trend, the higher the accumulated pension capital, the earlier men, and - to a smaller extent - women, tend to leave the work force.occupational pension; retirement decision; duration models

Estimation of multivariate probit models by exact maximum likelihood

In this paper, we develop a new numerical method to estimate a multivariate probit model. To this end, we derive a new decomposition of normal multivariate integrals that has two appealing properties. First, the decomposition may be written as the sum of normal multivariate integrals, in which the highest dimension of the integrands is reduced relative to the initial problem. Second, the domains of integration are bounded and delimited by the correlation coefficients. Application of a Gauss-Legendre quadrature rule to the exact likelihood function of lower dimension allows for a major reduction of computing time while simultaneously obtaining consistent and efficient estimates for both the slope and the scale parameters. A Monte Carlo study shows that the finite sample and asymptotic properties of our method compare extremely favorably to the maximum simulated likelihood estimator in terms of both bias and root mean squared error.Multivariate Probit Model, Simulated and Full Information Maximum Likelihood, Multivariate Normal Distribution, Simulations