Limits of end-state planning

Peer reviewedPreprin

Auditory critical periods: A review from system’s perspective

AbstractThe article reviews evidence for sensitive periods in the sensory systems and considers their neuronal mechanisms from the viewpoint of the system’s neuroscience. It reviews the essential cortical developmental steps and shows its dependence on experience. It differentiates feature representation and object representation and their neuronal mechanisms. The most important developmental effect of experience is considered to be the transformation of a naive cortical neuronal network into a network capable of categorization, by that establishing auditory objects. The control mechanisms of juvenile and adult plasticity are further discussed. Total absence of hearing experience prevents the patterning of the naive auditory system with subsequent extensive consequences on the auditory function. Additional to developmental changes in synaptic plasticity, other brain functions like corticocortical interareal couplings are also influenced by deprivation. Experiments with deaf auditory systems reveal several integrative effects of deafness and their reversibility with experience. Additional to developmental molecular effects on synaptic plasticity, a combination of several integrative effects of deprivation on brain functions, including feature representation (affecting the starting point for learning), categorization function, top–down interactions and cross-modal reorganization close the sensitive periods and may contribute to their critical nature. Further, non-auditory effects of auditory deprivation are discussed. To reopen critical periods, removal of molecular breaks in synaptic plasticity and focused training therapy on the integrative effects are required

Finitely forcible graphons with an almost arbitrary structure

Graphons are analytic objects representing convergent sequences of large graphs. A graphon is said to be finitely forcible if it is determined by finitely many subgraph densities, i.e., if the asymptotic structure of graphs represented by such a graphon depends only on finitely many density constraints. Such graphons appear in various scenarios, particularly in extremal combinatorics. Lovasz and Szegedy conjectured that all finitely forcible graphons possess a simple structure. This was disproved in a strong sense by Cooper, Kral and Martins, who showed that any graphon is a subgraphon of a finitely forcible graphon. We strenghten this result by showing for every $\varepsilon>0$ that any graphon spans a $1-\varepsilon$ proportion of a finitely forcible graphon

Scientific Reasoning and Achievement in a High School English Course

The hypothetical-deductive pattern of reasoning, an advanced reasoning model common to science, can be effectively transferred to the study of English and improve both English usage and reasoning skills. Though educators in the United States say that they already are teaching thinking and that the physical sciences and mathematics offer opportunities for learning higher-order reasoning skills, most observers agree that the goal of teaching students how to think has not been fulfilled. The reasons are varied. Perhaps the most serious deficiency is that teachers have never had a clear notion of just what advanced reasoning is--and just what to do to stimulate its development in students. My own search for effective ways to promote critical thinking during thirty years as a high school English teacher grew out of dissatisfaction with what was offered by various authors representing the humanities and behavioral and social sciences. Guided by my study of the paranormal and my association with college professors experimenting with various theories of intellectual devdopment, including those of Swiss psychologist Jean Piaget (known for his research of thought processes in children), I turned to the physical sciences for answers. Emphasizing the hypothetical-deductive pattern of reasoning in teaching critical thinking appeared feasible. So by means of a Piagetian-based, systematic instructional theory developed by Anton E. Lawson of Arizona State University, I used this reasoning model in my twelfth-grade English course at Grand Island Senior High in Grand Island, Nebraska, from 1982 to 1991. This reasoning model, common to science, can be effectivdy transferred to the field of English (and likely to other curriculum areas, as well as to everyday life); an academic discipline such as English can be used to help students develop higher-order thinking skills of a hypothetical-deductive nature

Scientific Reasoning and Achievement in a High School English Course

The hypothetical-deductive pattern of reasoning, an advanced reasoning model common to science, can be effectively transferred to the study of English and improve both English usage and reasoning skills. Though educators in the United States say that they already are teaching thinking and that the physical sciences and mathematics offer opportunities for learning higher-order reasoning skills, most observers agree that the goal of teaching students how to think has not been fulfilled. The reasons are varied. Perhaps the most serious deficiency is that teachers have never had a clear notion of just what advanced reasoning is--and just what to do to stimulate its development in students. My own search for effective ways to promote critical thinking during thirty years as a high school English teacher grew out of dissatisfaction with what was offered by various authors representing the humanities and behavioral and social sciences. Guided by my study of the paranormal and my association with college professors experimenting with various theories of intellectual devdopment, including those of Swiss psychologist Jean Piaget (known for his research of thought processes in children), I turned to the physical sciences for answers. Emphasizing the hypothetical-deductive pattern of reasoning in teaching critical thinking appeared feasible. So by means of a Piagetian-based, systematic instructional theory developed by Anton E. Lawson of Arizona State University, I used this reasoning model in my twelfth-grade English course at Grand Island Senior High in Grand Island, Nebraska, from 1982 to 1991. This reasoning model, common to science, can be effectivdy transferred to the field of English (and likely to other curriculum areas, as well as to everyday life); an academic discipline such as English can be used to help students develop higher-order thinking skills of a hypothetical-deductive nature

Cycles of length three and four in tournaments

Linial and Morgenstern conjectured that, among all $n$-vertex tournaments with $d\binom{n}{3}$ cycles of length three, the number of cycles of length four is asymptotically minimized by a random blow-up of a transitive tournament with all but one part of equal size and one smaller part. We prove the conjecture for $d\ge 1/36$ by analyzing the possible spectrum of adjacency matrices of tournaments. We also demonstrate that the family of extremal examples is broader than expected and give its full description for $d\ge 1/16$

In Vitro Flouride Resistance in a Cariogenic Streptococcus

Author Institution: Department of Botany and Microbiology, University of ArkansasStable fluoride-resistant mutants of Streptococcus mutans GS-5 were isolated with a stepwise selection procedure. First-step mutants were isolated at a frequency of 6.4 X 10~10 and demonstrated six maximal levels of resistance ranging from 400-1000 ug/ml sodium fluoride. Second-step mutants with higher levels of resistance were isolated at a frequency of 1.4 X 10~8. Second-step mutants demonstrated two maximal levels of resistance, 1600 and 3000 ug/ml sodium fluoride. Other than fluoride resistance, the characteristics of both first- and second-step mutants were similar to those of the parental strain. Growth rates did differ, however. First-step mutants exhibited slightly longer mass doubling times than the parental strain (average of 50 vs 45 min, respectively). Second-step mutants exhibited substantially longer mass doubling times (average of 71.5 min). The results suggest that fluoride resistance may be regulated by more than one gene, and that high levels of resistance may be due to a cumulative effect of at least two genes

Water-soluble sapphyrins

Sapphyrins are provided having appended functional groups that render the sapphyrin water-soluble. Such water-soluble sapphyrins are useful for photodynamic therapy, for example.Board of Regents, University of Texas Syste

Externally imposed electric field enhances plant root tip regeneration

In plants, shoot and root regeneration can be induced in the distinctive conditions of tissue culture (in vitro), but is also observed in intact individuals (in planta) recovering from tissue damage. Roots, for example, can regenerate their fully excised meristems in planta, even in mutants with impaired apical stem cell niches. Unfortunately, to date a comprehensive understanding of regeneration in plants is still missing. Here, we provide evidence that an imposed electric field can perturb apical root regeneration in Arabidopsis. Crucially, we explored both spatial and temporal competences of the stump to respond to electrical stimulation, respectively by varying the position of the cut and the time interval between excision and stimulation. Our data indicate that a brief pulse of an electric field parallel to the root is sufficient to increase by up to two-fold the probability of its regeneration, and to perturb the local distribution of the hormone auxin, as well as cell division regulation. Remarkably, the orientation of the root towards the anode or the cathode is shown to play a role