Algebraic Geometry Approach in Gravity Theory and New Relations between the Parameters in Type I Low-Energy String Theory Action in Theories with Extra Dimensions

On the base of the distinction between covariant and contravariant metric tensor components, a new (multivariable) cubic algebraic equation for reparametrization invariance of the gravitational Lagrangian has been derived and parametrized with complicated non - elliptic functions, depending on the (elliptic) Weierstrass function and its derivative. This is different from standard algebraic geometry, where only two-dimensional cubic equations are parametrized with elliptic functions and not multivariable ones. Physical applications of the approach have been considered in reference to theories with extra dimensions. The s.c. "length function" l(x) has been introduced and found as a solution of quasilinear differential equations in partial derivatives for two different cases of "compactification + rescaling" and "rescaling + compactification". New physically important relations (inequalities) between the parameters in the action are established, which cannot be derived in the case $l=1$ of the standard gravitational theory, but should be fulfilled also for that case.Comment: 4 pages; no figures; Talk at the Grassmannian Conference in Fundamental Cosmology "Grasscosmofun'09" (14-19 September 2009, University of Szczecin, Poland); prepared for the Proceedings of the Conference, which will appear in a special issue of the journal "Annalen der Physik" (Leipzig); "Ann.der Phys." style files use

Inhomogeneous Cosmological Models with Flat Slices Generated from the Einstein-de Sitter Universe

A family of cosmological models is considered which in a certain synchronized system of reference possess flat slices t = const. They are generated from the Einstein-de Sitter universe by a suitable transformation. Under physically reasonable presumptions these transformed models fulfil certain energy conditions.Comment: 8 pages, LaTeX, no figur

The abstract boundary---a new approach to singularities of manifolds

A new scheme is proposed for dealing with the problem of singularities in General Relativity. The proposal is, however, much more general than this. It can be used to deal with manifolds of any dimension which are endowed with nothing more than an affine connection, and requires a family \calc\ of curves satisfying a {\em bounded parameter property} to be specified at the outset. All affinely parametrised geodesics are usually included in this family, but different choices of family \calc\ will in general lead to different singularity structures. Our key notion is the {\em abstract boundary\/} or {\em $a$-boundary\/} of a manifold, which is defined for any manifold \calm\ and is independent of both the affine connection and the chosen family \calc\ of curves. The $a$-boundary is made up of equivalence classes of boundary points of \calm\ in all possible open embeddings. It is shown that for a pseudo-Riemannian manifold (\calm,g) with a specified family \calc\ of curves, the abstract boundary points can then be split up into four main categories---regular, points at infinity, unapproachable points and singularities. Precise definitions are also provided for the notions of a {\em removable singularity} and a {\em directional singularity}. The pseudo-Riemannian manifold will be said to be singularity-free if its abstract boundary contains no singularities. The scheme passes a number of tests required of any theory of singularities. For instance, it is shown that all compact manifolds are singularity-free, irrespective of the metric and chosen family \calc.Comment: 40 pages (amslatex) + 5 uuencoded figures (A postscript version is also available on http://einstein.anu.edu.au/), CMA Maths. Research Report No. MRR028-9

Nemi arányok és a rokonszenvi választások kapcsolatának vizsgálata enyhén értelmi fogyatékos tanulókat integráló osztályokban

Tanulmányunkban enyhén értelmi fogyatékos gyermekeket integráló osztályközösségek állnak a középpontban. A vizsgálati mintát négy 20 főből álló osztály alkotta, melyek közül kettőben fiúk voltak többen, és az egyikben fiú, a másikban lány volt az integrált tanuló. A másik két közösségben a lányok képviselték a többséget, egy-egy fiú, illetve lány fogyatékos diákkal közöttük. Célunk a közösségek nemi arányainak és a rokonszenvi választások összefüggésének megfigyelése volt. Ennek érdekében minőségi fókuszú elemzést végeztünk. Módszerül a szociometriát alkalmaztuk, az adatok feldolgozása pedig a Smetry szoftverrel történt. Eredményeink közül kiemeljük, hogy a vizsgált közösségekben a nem viszonzott rokonszenvi választások közül az azonos nemek közöttiek voltak nagyobb számban, illetve az azonos vagy „közeli” szociometriai státuszú társ felől érkező kapcsolódási igény több esetben realizálódott a tanulók között. Az utolsó feltételezésünk – lány többségű osztályokban rosszabb a lányok pozíciója, különösen, ha integráltak - relevanciáját jól látható eredmények bizonyították. Abban az osztályban lett a legkedvezőtlenebb a lányok szociometriai helyzete, ahol ők képviselik a többséget és az integrált tanuló is lány

Timelike and null focusing singularities in spherical symmetry: a solution to the cosmological horizon problem and a challenge to the cosmic censorship hypothesis

Extending the study of spherically symmetric metrics satisfying the dominant energy condition and exhibiting singularities of power-law type initiated in SI93, we identify two classes of peculiar interest: focusing timelike singularity solutions with the stress-energy tensor of a radiative perfect fluid (equation of state: $p={1\over 3} \rho$) and a set of null singularity classes verifying identical properties. We consider two important applications of these results: to cosmology, as regards the possibility of solving the horizon problem with no need to resort to any inflationary scenario, and to the Strong Cosmic Censorship Hypothesis to which we propose a class of physically consistent counter-examples.Comment: 26 pages, 2 figures, LaTeX file. Submitted to Phys. Rev.

Gender and budget

Neoclassical approach to economics failed to recognize and evaluate the importance in producing the human capital, of work of households which is predominantly performed by women. Extensive research, however, indicates that neglecting such issues may lead to a lower growth rate, and at the same time aspects of human equity are seriously disregarded. To eliminate this deficiency, there is a stronger tendency in the world to involve gender sensitiveness into the process of budget-making. There is a wide range of tools in the process, extending from the gendered analysis of the impacts on beneficiaries of budget, to examining the gender-disaggregated impacts of expenditure or tax incidence. The involvement of participants of civil society helps to make the budgetmaking a more open, participatory process.heterodox economics, gender-sensitive budget, gender equality

“Getting the old limbs going”: Exploring the emotional and cognitive benefits of exercise and the barriers to participation in older adults

The aim of this thesis was to explore how community-based exercise brings cognitive and emotional benefits to older people and which barriers prevent the participation of inactive older adults. The thesis was designed into a series of 6 research studies. Chapter 2 synthesised the quantitative and qualitative evidence regarding the impact of community-based exercise programmes on cognitive function and emotional wellbeing. Although exercise positively impacts emotional wellbeing, there were few studies regarding cognitive benefits. Also, adherence was influenced by factors at different levels of the ecological model. Chapters 3 and 4 explored the perspectives of older adults actively engaged in community-based exercise programmes and their exercise instructors. These studies used qualitative methods to identify which factors participants perceive as crucial for short-term and long-term adherence. The results showed that the perspectives of older adults and their instructors were aligned; the instructors had an accurate understanding of the needs and preferences of older adults and purposefully targeted them. Program design and teaching style were key for successful sessions, and both skill development and socialising sustained the long-term engagement of older adults in exercise. Importantly, the recognition of benefits to cognitive function and emotional wellbeing also contributed to continued adherence. Chapters 5 and 6 focused on older adults who are inactive or who are transitioning to/from being inactive. Chapter 5 was a feasibility study for a randomised control design that included measures of adherence as well as pre-and post-intervention measures of cognitive function and emotional wellbeing. It followed previously inactive older adults who took part in a 12-week exercise programme, either indoor cycling or cheerleading. The findings demonstrated the positive impact of both programmes on emotional wellbeing, cognitive function, and blood pressure reactivity. Cheerleading, which was more cognitively challenging, also produced superior executive function and emotional resilience improvements than indoor cycling. Chapter 6 explored what may facilitate the engagement of inactive older adults. As this coincided with major changes happening at the policy, environmental and organisational levels, because of the Covid-19 pandemic, the study also explored how previously active older adults responded to the closure of community-based exercise programmes. Mixed methods were used to investigate the facilitators and barriers to physical activity in both inactive and previously active older adults. The interviews showed that having a sense of purpose was a key source of motivation to exercise. It was influenced by both the belief in the importance of exercise and the affective valence participants assigned to exercise. For previously inactive older adults, missing the social context of exercise led to inactivity. However, all participants found a renewed purpose in walking and outdoor activities as a response to the lockdown restrictions. Throughout the studies of this thesis, several characteristics of exercise programmes that suit the intrapersonal factors, health needs and preferences of older adults were identified, and recommendations were developed to improve current community-based services

Computer laboratory in medical education for medical students

Five generations of the second year students at the Zagreb University School of Medicine were interviewed through an anonymous questionnaire on their use of personal computers, Internet, computer laboratories and computer-assisted education in general. Results show advance in using the information and communication technology by medical students during the period from 1998/99 to 2002/03. However, their positive opinion about computer laboratory depends on installed capacities: the better technology in the computer laboratory – the more positive opinion of it