Cosmic Microwave Background Radiation Anisotropy Induced by Cosmic Strings

We report on a current investigation of the anisotropy pattern induced by cosmic strings on the cosmic microwave background radiation (MBR). We have numerically evolved a network of cosmic strings from a redshift of $Z = 100$ to the present and calculated the anisotropies which they induce. Based on a limited number of realizations, we have compared the results of our simulations with the observations of the COBE-DMR experiment. We have obtained a preliminary estimate of the string mass-per-unit-length $\mu$ in the cosmic string scenario.Comment: 8 pages of TeX - [Color] Postscript available by anonymous ftp at ftp://fnas08.fnal.gov:/pub/Publications/Conf-94-197-A, FERMILAB-Conf-94/197-

Home accidents amongst elderly people: A locality study in Scotland

Aim The aim of this locality study was to collect information on reported and unreported accidents amongst elderly people living in one locality in Scotland. Method Postal Survey- A postal questionnaire was sent to 3,757 men and women aged 65+ years living in one locality. The questionnaire asked respondents to indicate how many accidents they had experienced in the past twelve months, plus to indicate type and location. Information was gathered on living arrangements, ethnicity, gender, age and deprivation. Respondents were asked if they would be willing to take part in an interview study. Interview Study - One hundred elders who had had at least one accident in the previous twelve months were interviewed. Results Postal Survey - Over a third of the respondents in the postal survey reported having had an accident in the previous twelve months. Bumps and drops and falls were the most common type of accident. Most accidents happened in the kitchen. Women reported more falls than men and those living alone reported more accidents than those living with others. Age was associated with the prevalence of accidents, but the association was somewhat curvilinear, with accidents decreasing with age and then increasing again. Interview Study – Interviewees found it hard to differentiate one accident from another. Considerable reluctance to visit the GP after an accident was noted, with many not attending even for serious accidents. Almost forty percent were ‘very’ distressed after their accident, and a quarter reported a loss of confidence. However, most did not worry about accidents. Few thought that their age, health or medications were a cause of their accidents

Comments on scalar-tensor representation of nonlocally corrected gravity

The scalar-tensor representation of nonlocally corrected gravity is considered. Some special solutions of the vacuum background equations were obtained that indicate to the nonequivalence of the initial theory and its scalar-tensor representation.Comment: 6 pages, refs adde

On the width of the last scattering surface

We discuss the physical effects of some accelerated world models on the width of the last scattering surface (LSS) of the cosmic microwave background radiation (CMBR). The models considered in our analysis are X-matter (XCDM) and a Chaplygin type gas. The redshift of the LSS does not depend on the kind of dark energy (if XCDM of Chaplygin). Further, for a Chaplygin gas, the width of the LSS is also only weakly dependent on the kind of scenario (if we have dark energy plus cold dark matter or the unified picture).Comment: 10 pages, 1 figure, 2 tables, accepted to IJMP

Some FRW Models of Accelerating Universe with Dark Energy

The paper deals with a spatially homogeneous and isotropic FRW space-time filled with perfect fluid and dark energy components. The two sources are assumed to interact minimally, and therefore their energy momentum tensors are conserved separately. A special law of variation for the Hubble parameter proposed by Berman (1983) has been utilized to solve the field equations. The Berman's law yields two explicit forms of the scale factor governing the FRW space-time and constant values of deceleration parameter. The role of dark energy with variable equation of state parameter has been studied in detail in the evolution of FRW universe. It has been found that dark energy dominates the universe at the present epoch, which is consistent with the observations. The physical behavior of the universe is discussed in detail.Comment: 10 pages, 5 figure

Large Angular Scale CMB Anisotropy Induced by Cosmic Strings

We simulate the anisotropy in the cosmic microwave background (CMB) induced by cosmic strings. By numerically evolving a network of cosmic strings we generate full-sky CMB temperature anisotropy maps. Based on $192$ maps, we compute the anisotropy power spectrum for multipole moments $\ell \le 20$. By comparing with the observed temperature anisotropy, we set the normalization for the cosmic string mass-per-unit-length $\mu$, obtaining $G\mu/c^2=1.05 {}^{+0.35}_{-0.20} \times10^{-6}$, which is consistent with all other observational constraints on cosmic strings. We demonstrate that the anisotropy pattern is consistent with a Gaussian random field on large angular scales.Comment: 4 pages, RevTeX, two postscript files, also available at http://www.damtp.cam.ac.uk/user/defects/ to appear in Physical Review Letters, 23 September 199

Tele-operated high speed anthropomorphic dextrous hands with object shape and texture identification

This paper reports on the development of two number of robotic hands have been developed which focus on tele-operated high speed anthropomorphic dextrous robotic hands. The aim of developing these hands was to achieve a system that seamlessly interfaced between humans and robots. To provide sensory feedback, to a remote operator tactile sensors were developed to be mounted on the robotic hands. Two systems were developed, the first, being a skin sensor capable of shape reconstruction placed on the palm of the hand to feed back the shape of objects grasped and the second is a highly sensitive tactile array for surface texture identification

Parametrization of dark energy equation of state Revisited

A comparative study of various parametrizations of the dark energy equation of state is made. Astrophysical constraints from LSS, CMB and BBN are laid down to test the physical viability and cosmological compatibility of these parametrizations. A critical evaluation of the 4-index parametrizations reveals that Hannestad-M\"{o}rtsell as well as Lee parametrizations are simple and transparent in probing the evolution of the dark energy during the expansion history of the universe and they satisfy the LSS, CMB and BBN constraints on the dark energy density parameter for the best fit values.Comment: 11 page

Friction of Fabric Material and Bearing Metals

This thesis discusses the results obtained by experiments carried out on the friction of 'Fabric' material. It presents a general analysis of the suitability of cotton, asbestos, and metals as friction materials, and the combination of these materials in bonded form as brake and clutch linings. The tests to be described were carried out in order to determine the coefficient of friction, wear properties, and general behaviour of a few of the many fabric materials under varying conditions of load, rubbing speed, and temperature. Special study has been given to the variation of frictional resistance at speeds varying from 0.5 to 50 feet per minute. It has been shown, that with a cotton bonded fabric the frictional resistance is very high at crawl speeds, and gradually diminishes as the speed increases. The effect of temperature on the wear of fabric material and on the destruction of the binder used has also been studied. Throughout the experiments it has been noted that a thin film of iron oxide changes the value of the coefficient of friction almost as much as a film of oil