The double slit experiment and the time reversed fire alarm

When both slits of the double slit experiment are open, closing one paradoxically increases the detection rate at some points on the detection screen. Feynman famously warned that temptation to "understand" such a puzzling feature only draws us into blind alleys. Nevertheless, we gain insight into this feature by drawing an analogy between the double slit experiment and a time reversed fire alarm. Much as closing the slit increases probability of a future detection, ruling out fire drill scenarios, having heard the fire alarm, increases probability of a past fire (using Bayesian inference). Classically, Bayesian inference is associated with computing probabilities of past events. We therefore identify this feature of the double slit experiment with a time reversed thermodynamic arrow. We believe that much of the enigma of quantum mechanics is simply due to some variation of time's arrow. In further support of this, we employ a plausible formulation of the thermodynamic arrow to derive an uncertainty in classical mechanics that is reminiscent of quantum uncertainty.Comment: Last two paragraphs of Discussion section are an addendum to the version accepted at Il Nuovo Cimento B

Exploring masses and CNO surface abundances of red giant stars

A grid of evolutionary sequences of stars in the mass range $1.2$-$7$ M$_{\odot}$, with solar-like initial composition is presented. We focus on this mass range in order to estimate the masses and calculate the CNO surface abundances of a sample of observed red giants. The stellar models are calculated from the zero-age main sequence till the early asymptotic giant branch (AGB) phase. Stars of M $\leqslant$ $2.2$M$_{\odot}$ are evolved through the core helium flash. In this work, an approach is adopted that improves the mass determination of an observed sample of 21 RGB and early AGB stars. This approach is based on comparing the observationally derived effective temperatures and absolute magnitudes with the calculated values based on our evolutionary tracks in the Hertzsprung-Russell diagram. A more reliable determination of the stellar masses is achieved by using evolutionary tracks extended to the range of observation. In addition, the predicted CNO surface abundances are compared to the observationally inferred values in order to show how far standard evolutionary calculation can be used to interpret available observations and to illustrate the role of convective mixing. We find that extra mixing beyond the convective boundary determined by the Schwarzschild criterion is needed to explain the observational oxygen isotopic ratios in low mass stars. The effect of recent determinations of proton capture reactions and their uncertainties on the $^{16}$O$/^{17}$O and $^{14}$N$/^{15}$N ratios is also shown. It is found that the $^{14}$N$($ p$,\gamma)^{15}$O reaction is important for predicting the $^{14}$N$/^{15}$N ratio in red giants.Comment: 12 pages, 10 figures, 3 tables, published in MNRA

MEASURING THE SUCCESS OF COUNTRY FOOTBALL CLUBS

Until the last quarter of the twentieth century, non-metropolitan Australian Rules football clubs prospered as volunteer organisations, operating in regions that were protected by distance from clubs in larger, competing leagues. They acted as places that people valued and were important components of social capital in their communities, and in turn, received subsidies from other community groups that reduced operating costs. Clubs appear to have measured success in terms of their ability to attract the talent needed to build a winning team that would boost the prestige of both the club and its local community. The Victorian Football League’s regulations about player payment and mobility gave country football clubs the opportunity to offer attractive terms to League players, and this prevented the game’s most powerful league, from crowding out its rivals. The circumstances that were favourable to country football clubs have changed with the formation of a major league, the Australian Football League. The televising of matches nationwide allowed people in even remote regions to watch AFL games. Economic and demographic decline in country areas, greater mobility and the lure of metropolitan jobs has made it difficult for clubs to retain players. In this challenging economic environment, many country football clubs have been unable to survive in their own right. This paper reports on a survey of administrators of Victorian country football clubs as to their perceptions of what constitutes ‘success’ in this new environment. It provides information about how individual clubs are responding to broad changes that are beyond their control, and offers evidence about the ability of local football clubs to continue to play their traditional role as places of importance and generators of social capital in regional communities.

Combinatorial Penalties: Which structures are preserved by convex relaxations?

We consider the homogeneous and the non-homogeneous convex relaxations for combinatorial penalty functions defined on support sets. Our study identifies key differences in the tightness of the resulting relaxations through the notion of the lower combinatorial envelope of a set-function along with new necessary conditions for support identification. We then propose a general adaptive estimator for convex monotone regularizers, and derive new sufficient conditions for support recovery in the asymptotic setting

Practical quantitative measurement of graticule misalignment relative to collimator axis of rotation.

We design a practical procedure for measuring translational and rotational misalignment of graticule with collimator axis of rotation and collimator jaws, respectively. The procedure's quantitative results are accurate to less than 0.2 mm (at isocenter) and do not assume alignment of radiation focal spot with collimator axis of rotation. When provided with these quantitative results, the manufacturer can custom-adjust graticules to the purchaser's collimator head

Zika, Pregnancy, and the Law

The public health emergency surrounding the spread of the Zika virus has resurrected and brought into sharp relief some of the most vexing questions surrounding the relationship between pregnancy and law: the appropriate circumstances, if any, in which fetal tissue research is permissible; when and how the government may sponsor statements intended to influence reproductive decisions; and how to balance the health and rights of both women and their unborn children when health threats target both