We introduce center-like subsets Z*(R,f), Z**(R,f) and Z1(R,f), where R is a ring and f is a map from R to R. For f a derivation or a non-identity epimorphism and R a suitably-chosen prime or semiprime ring, we prove that these sets coincide with the center of R.

We perceive a stable visual world, which enables successful interaction with our environment, despite movements of the eyes, head, and body. How are such perceptions formed? One possibility is that retino-centric visual input is transformed into representations at higher levels, such as head-, body-, or world-centered representations. We investigated this hypothesis using the tilt aftereffect i...

Coordinated movements of the eye, head, and body are used to redirect the axis of gaze between objects of interest. However, previous studies of eye-head gaze shifts in head-unrestrained primates generally assumed the contribution of body movement to be negligible. Here we characterized eye-head-body coordination during horizontal gaze shifts made by trained rhesus monkeys to visual targets whi...

The multiheaded one (mh-1) strain, isolated from inbred crossings of wild type Hydra magnipapillata, develops additional heads along the body axis. This strain reproduces asexually by budding like the wild type (wt) does. We found that young polyps have a wt-like shape and display wt-like properties. When they grow in size and before they produce extra heads along the body axis, the tissue betw...

Control of head position during postural responses is important to facilitate both the interpretation of vestibular signals and the stabilization of gaze. In these experiments, we compared head stabilization for two different postural tasks: 1) in response to perturbations at the head, and 2) in response to perturbations induced at the support surface, which perturb both body and head position....

The origin of the bilaterian head is a fundamental question for the evolution of animal body plans. The head of bilaterians develops at the anterior end of their primary body axis and is the site where the brain is located. Cnidarians, the sister group to bilaterians, lack brain-like structures and it is not clear whether the oral, the aboral, or none of the ends of the cnidarian primary body a...

background: adolescent pregnancy and childbirth are associated with increased risk and challenges for both mothers and birth outcomes. objective: to investigate the associations of growth change over time with parenting factors and to compare the differences between children born to adolescent and adult mothers in taiwan. materials and methods: the dataset retrieved from taiwan birth cohort stu...