With the advent of hypertext it has become widely accepted that the departure from the so-called " linear " structure of paper increases the likelihood of readers or users becoming lost. In this paper we will discuss this aspect of hypertext in terms of its validity, the lessons to be learned from the psychology of navigation and the applicability of the navigation metaphor to the hypertext dom...

We report 60 and 90 µm observations of 7 millisecond pulsars with ISO. The pulsar PSR B1257+12 is orbited by three planets, and other millisecond pulsars may be orbited by dust disks that represent planets that failed to form or their residue. We do not detect any infrared emission from the 7 pulsars in our sample, and typical upper limits are 100 mJy. Using a simple model, we constrain the typ...

This study was carried out among urban, rural and refugee camp populations in three localities (Rimal, Jabalia Village, Jabalia Refugee Camp), in Gaza Governorates – Palestine. School children between 6 and 11 years old were examined. The prevalence of intestinal parasites among 309 school children was higher in the rural area (53.3%) and the Refugee Camp (48.0%) than in urban areas (33.0%). Ma...

OBJECTIVE To describe the behavior of mortality in Mexico through four indicators from 1990 to 2012. MATERIAL AND METHODS The official mortality and population records of Mexico were used. RESULTS An advance was achieved for children under five years of age, with a decrease in mortality, although there was an increase in the years of potential life lost (YPLL) from 2008 for this age group. ...

Pulsar spindown forms a reliable yet enigmatic prototype for the energy loss processes in many astrophysical objects including accretion disks and back holes. In this paper we review the physics of pulsar magnetospheres, concentrating on recent developmen ts in force-free modeling of the magnetospheric structure. In particular, we discuss a new method for solving the equations of time-dependent...

primary man in trying to find food went everywhere. but by forming ranching arranged a chain of places and became emigrant. by happening industrial revolution, human life was centralized on one place.  places that base on its advantages make different biologic and behavioral types. forming cities in seaboard, river shore, boundary of mountains and champaign cause to make different cultures that...