Group and individual time management tools: what you get is not what you need

Some studies of diaries and scheduling systems have considered how individuals use diaries with a view to proposing requirements for computerised time management tools. Others have focused on the criteria for success of group scheduling systems. Few have paid attention to how people use a battery of tools as an ensemble. This interview study reports how users exploit paper, personal digital assistants (PDAs) and a group scheduling system for their time management. As with earlier studies, we find many shortcomings of different technologies, but studying the ensemble rather than individual tools points towards a different conclusion: rather than aiming towards producing electronic time management tools that replace existing paper-based tools, we should be aiming to understand the relative strengths and weaknesses of each technology and look towards more seamless integration between tools. In particular, the requirements for scheduling and those for more responsive, fluid time management conflict in ways that demand different kinds of support

Introduction to the Symposium: Causal Inference and Public Health

Assessing the extent to which public health research findings can be causally interpreted continues to be a critical endeavor. In this symposium, we invited several researchers to review issues related to causal inference in social epidemiology and environmental science and to discuss the importance of external validity in public health. Together, this set of articles provides an integral overview of the strengths and limitations of applying causal inference frameworks and related approaches to a variety of public health problems, for both internal and external validity

On the Possibility of Optical Unification in Heterotic Strings

Recently J. Giedt discussed a mechanism, entitled optical unification, whereby string scale unification is facilitated via exotic matter with intermediate scale mass. This mechanism guarantees that a virtual MSSM unification below the string scale is extrapolated from the running of gauge couplings upward from M_Z^o when an intermediate scale desert is assumed. In this letter we explore the possibility of optical unification within the context of weakly coupled heterotic strings. In particular, we investigate this for models of free fermionic construction containing the NAHE set of basis vectors. This class is of particular interest for optical unification, because it provides a standard hypercharge embedding within SO(10), giving the standard k_Y = 5/3 hypercharge level, which was shown necessary for optical unification. We present a NAHE model for which the set of exotic SU(3)_C triplet/anti-triplet pairs, SU(2)_L doublets, and non-Abelian singlets with hypercharge offers the possibility of optical unification. Whether this model can realize optical unification is conditional upon these exotics not receiving Fayet-Iliopoulos (FI) scale masses when a flat direction of scalar vacuum expectation values is non-perturbatively chosen to cancel the FI D-term, xi, generated by the anomalous U(1)-breaking Green-Schwarz-Dine-Seiberg-Wittten mechanism. A study of perturbative flat directions and their phenomenological implications for this model is underway. This paper is a product of the NFS Research Experiences for Undergraduates and the NSF High School Summer Science Research programs at Baylor University.Comment: 16 pages. Standard Late

The practical application of scintillometers in determining the surface fluxes of heat, moisture and momentum

This thesis has collated one review chapter and five experiments concerned with addressing the question, 'how successful is the scintillometer method in determining the surface fluxes of heat, moisture and momentum and under what circumstances does it appear to fail?' Answering this question is important as a workable scintillation method provides the meteorologist with spatial integrated measurements of the surface fluxes at kilometre scales. With such a tool, ground-truth validation of remote sensing systems is possible, water balance studies can be conducted at catchment scales and energy balance experiments extended over slightly non-homogeneous terrain. Using electromagnetic scintillation to infer turbulence quantities is a fairly recent development. Although our interest lies in estimating the surface fluxes Chapter 3 makes it very clear that the foundation of the scintillation method is deeply rooted in at times questionable combination of turbulence and wave propagation theory. The novice must appreciate the important steps and assumptions in the scintillation method. Purchasing a scintillometer off-the-shelf is no guarantee of reliable measurements.How well this thesis has answered the treatise depends to an extent on the relative performance of the scintillometer method against some benchmark. For these scintillation experiments this benchmark was the eddy covariance method, selected for convenience and familiarity. In many ways this selection is a compromise as different temporal and spatial band-widths are used by each method. Scintillation measures the ensemble average of spatial fluctuations in the refractive-index along the propagation path. The eddy covariance technique makes measurements at one point in space as a function of time. The time average of the eddy covariance method is considered to be an ensemble average. Depending on atmospheric stability the eddy covariance method may require several tens of minutes to integrate the energy from all eddy scales contributing to the surface fluxes. In comparison, the scintillometer can provide statistically stable data within minutes because it only measures in the inertial-convective subrange of frequencies. In light of such differences any comparison between methods should be made with a tongue-in-cheek approach with the state of the atmosphere and surface conditions carefully scrutinised to explain any discrepancies. The strength of using the eddy covariance technique as a comparison is because it identifies any marked deviations from the norm experienced by the scintillation method. Success is in comprehending what caused these deviations not through obtaining the perfect half-hour correlation between methods. The five experiments in this thesis table such deviations and propose explanations for their particular scintillometer type and application. What follows, are the salient facts gleamed from this research.The experiments using the inner scale meter and the semiconductor laser diode highlighted the pluses and minuses ofdependence for laser scintillometers. This dependence required a correction to the measured signal variance using the spectra of Hill (1978), but it also provided information on the magnitude ofand ultimately a measure of. In the case of the semiconductor laser diode scintillometer,was indirectly determined using a measurement of average windspeed and crop height. This approach proved successful in the calculation of. In contrast, the inner scale meter measuredusing the difference in received signal variances between a gas laser and a large aperture scintillometer having littledependence. This latter approach was particularly sensitive to small signal differences and caused considerable scatter in thecomparisons. Despite a coarse result for,still compared favourably to. In addition to thedependence the laser scintillometers suffered from signal saturation in the presence of strong turbulence. This path limited the laser scintillometers and consequently the inner scale meter to operation over short distances ( L The near-infrared large aperture scintillometer was designed to overcome the shortcomings of the laser scintillometers. It is most suited to calculations ofand it successfully did so as a component of the inner scale meter. This scintillometer however performed poorly for the rice paddy experiment. Hereand at times up to 40% of the received signal variance could be attributed to correlated T-Q fluctuations. The rice paddy experiment highlighted the effect of absorption scintillations on the large aperture signal variance. This effect was also apparent in the test of the two-wavelength scintillometer at Ahipara (Chapter 7). Subsequent modification to the scintillometer's electronic filtering alleviated this problem. If large aperture near-infrared scintillometers are still being built based on the original design of Ochs and Cartwright (1980) then theoutput signal may contain the effect of absorption fluctuations in addition to refractive fluctuations.The optical wavelength scintillometers, whether they are the laser or the large aperture types, struggled to provide a measurement ofbecause they are less sensitive to humidity fluctuations than temperature fluctuations. This was confirmed by observations of the relative contributions made by,, andtoat visible to near-infrared wavelengths. The opposite was shown to be true at microwave wavelengths and so measuringrequires a microwave scintillometer. The two-wavelength combination of microwave and large aperture scintillometers proved successful in calculating bothand, provided the effect of low frequency path-averaged humidity fluctuations was filtered from the scintillometer signals. The microwave scintillometer was shown to be sensitive to inertial-convective fluctuations and capable of calculating.When mechanical turbulence is minimal and one is interested in unstable atmospheric conditions then the free convection formula developed for the two-wavelength scintillometer provided a reasonable estimate of. However measuring at height and under very unstable conditions means the scintillometer signal variance can be corrupted by the passage of the growing CBL. Because, the scintillometer signal variance can become very small and possibly undetectable from signal noise. Unpublished data from the Ahipara experiment showed the large aperture scintillometer operated at 10 m and can provide reliable estimates ofby also using a free convective scaling formula (De Bruin et al., 1995). This result is in-line with the observations of De Bruin et al. (1995) who also showed coarse measurements ofwere sufficient to ensure reasonable calculations ofand.Until microwave scintillometers were used in these experiments measurements were confined close to the ground. Microwave technology required installing the scintillometer at some minimum height to avoid surface reflection of the propagated signal. With increased height and distance so grew the requirements to preserve MOST. The valley experiment at Brancott was the first time the effect of advection was observed on the scintillation measurements. The scintillometer footprint was sensitive to the effects of the dry-to-wet transition and the entrainment of the dry and warm air into the newly formed surface boundary layer. Under these conditions the scintillometers could not distinguish the source of the additional signal variance and the scintillometer method failed. It was also highly unlikely under these circumstances the T-Q correlation held at the scintillometer beam height.In light of these summarised results we present here some recommendations.Laser scintillometers or scintillometers which incorporate lasers such as the inner scale meter are only useful over short distances as they are limited by signal saturation and a dependence on. Theoretical advances in describing the scintillometer signal variance in strong turbulence will still require a powerful and stable laser scintillometer to implement such advances if operation over kilometre distances is required.The near-infrared large aperture scintillometer is simple and inexpensive to construct. It has minimal dependence onand it can operate over kilometre distances without signal saturation. It probably is not suited to measurements over well-irrigated surfaces because it is most sensitive to temperature fluctuations. This scintillometer performs well in unstable conditions using free convective scaling.The microwave scintillometer and large aperture near-infrared scintillometer combination can provide reliable estimates ofand. They should be used over reasonable homogeneous terrain with sufficient fetch to guarantee reliable measurements. This two-wavelength combination can estimate bothandunder unstable conditions using free convective scaling.</p

Investigation of Quasi--Realistic Heterotic String Models with Reduced Higgs Spectrum

Quasi--realistic heterotic-string models in the free fermionic formulation typically contain an anomalous U(1), which gives rise to a Fayet-Iliopolous term that breaks supersymmetry at the one--loop level in string perturbation theory. Supersymmetry is restored by imposing F- and D-flatness on the vacuum. In Phys. Rev. D 78 (2008) 046009, we presented a three generation free fermionic standard-like model which did not admit stringent F- and D-flat directions, and argued that the all the moduli in the model are fixed. The particular property of the model was the reduction of the untwisted Higgs spectrum by a combination of symmetric and asymmetric boundary conditions with respect to the internal fermions associated with the compactified dimensions. In this paper we extend the analysis of free fermionic models with reduced Higgs spectrum to the cases in which the SO(10) symmetry is left unbroken, or is reduced to the flipped SU(5) subgroup. We show that all the models that we study in this paper do admit stringent flat directions. The only examples of models that do not admit stringent flat directions remain the strandard-like models of reference Phys. Rev. D 78 (2008) 046009.Comment: 38 pages, 1 figur

Public sector reforms, privatisation and regimes of control in a Chinese enterprise

The Chinese economic reform has recently become a major focus of attention around the world. The underlying rationale for the Chinese government's privatisation and public sector reforms is the view that reformed state enterprises and privately managed firms will demonstrate superior management control and better performance, and hence encourage economic growth and employment. There are very few intensive case studies published in English journals studying whether firms privatised in China have reversed previous losses and introduced better management controls, leading to increased investment, productivity, and overall organizational effectiveness and efficiency. The researchers do not seek to deny the control problems of Chinese SOEs, but question the consequences of the new controls installed during the post-privatisation period. The paper also reveals a declining tendency in employment; altered distributions of wealth ? especially to the state ? and labour, and a lack of improvements in the accountability of privatised companies. Overall, the paper argues, the aims of reform policies in China, including better control, increased profitability and an improved working life for Chinese people, have not materialized. The paper calls for more research on the above issues in the Chinese context

Tests of the Gravitational Inverse-Square Law

We review recent experimental tests of the gravitational inverse-square law and the wide variety of theoretical considerations that suggest the law may break down in experimentally accessible regions.Comment: 81 pages, 10 figures, submitted by permission of the Annual Review of Nuclear and Particle Science. Final version of this material is scheduled to appear in the Annual Review of Nuclear and Particle Science Vol. 53, to be published in December 2003 by Annual Reviews, http://AnnualReviews.or

Oscillons in dilaton-scalar theories

It is shown by both analytical methods and numerical simulations that extremely long living spherically symmetric oscillons appear in virtually any real scalar field theory coupled to a massless dilaton (DS theories). In fact such "dilatonic" oscillons are already present in the simplest non-trivial DS theory -- a free massive scalar field coupled to the dilaton. It is shown that in analogy to the previously considered cases with a single nonlinear scalar field, in DS theories there are also time periodic quasibreathers (QB) associated to small amplitude oscillons. Exploiting the QB picture the radiation law of the small amplitude dilatonic oscillons is determined analytically.Comment: extended discussion on stability, to appear in JHEP, 29 pages, 7 figure

Microbial impacts of CO2 transport in Sherwood Sandstone

Work carried out by BGS and the Japan Atomic Energy Authority (JAEA) has shown that microbial processes can have profound effects on the transport properties of host rock (i.e. the movement of fluids and contaminants through the host material) relevant to radioactive waste disposal. Recent research, performed as part of the BGS Radtran project, has examined Sherwood Sandstone samples in the context of radioactive waste disposal; this particular formation is also a potential reservoir for carbon dioxide storage in the UK. As part of the BGS opportunities fund programme, this project has, for the first time, evaluated interactions between fluids saturated with carbon dioxide/Sherwood Sandstone/microbes (Pseudomonas aeruginosa) in transport experiments, using BGS developed apparatus under pressurised subsurface conditions. This pilot study has highlighted the impacts of differences in the physical characteristics of core Sherwood Sandstone samples collected adjacent to each other in a core sample, and the ability of P. aeruginosa to survive in CO2 saturated artificial groundwater and the potential to form a biofilm in an environment suitable likely to be found at a carbon capture and storage location. These results demonstrate that in this short study, the injection of P. aeruginosa into the biotic experiment does not appear to impact on the physical transport properties of the Sherwood Sandstone, although the presence of CO2 appears to enhance the mobilisation of a number of chemical species. However, in other work which utilised the same organism and rock type but without introduction of CO2 saturated fluid, post-inoculation injection changes were observed. These included short but rapid saw-tooth like changes in the pressure profile (Wragg et al, 2012). These impacts were not observed in the current study which suggests that the CO2 saturated fluid was impacting on the ability of the microbes to alter permeability. This short study has, however, indicated the need to carry out longer term investigations to reproduce these initial findings

Modeling water waves beyond perturbations

In this chapter, we illustrate the advantage of variational principles for modeling water waves from an elementary practical viewpoint. The method is based on a `relaxed' variational principle, i.e., on a Lagrangian involving as many variables as possible, and imposing some suitable subordinate constraints. This approach allows the construction of approximations without necessarily relying on a small parameter. This is illustrated via simple examples, namely the Serre equations in shallow water, a generalization of the Klein-Gordon equation in deep water and how to unify these equations in arbitrary depth. The chapter ends with a discussion and caution on how this approach should be used in practice.Comment: 15 pages, 1 figure, 39 references. This document is a contributed chapter to an upcoming volume to be published by Springer in Lecture Notes in Physics Series. Other author's papers can be downloaded at http://www.denys-dutykh.com