567 research outputs found
The Last Thing We Need Is Another Shelter
Segre suggests that family homelessness is merely the latest and most devastating example of America\u27s lack of commitment to children and families. The history of human services for children is presented to show that, both at the community and at the policy levels, this population and its needs have been neglected, subjected to fragmentation, and consistently downgraded on our lists of priorities. The societal values that have led to this situation are discussed and revealed as still reflecting an individualistic, frontier outlook, which is, however, becoming an anachronism. The need for a child/family policy is stressed, as is the urgency of reexamining and modifying some of our basic tenets in order to prevent the recurrence of such inhumane outcomes as homelessness
Recursiveness, Switching, and Fluctuations in a Replicating Catalytic Network
A protocell model consisting of mutually catalyzing molecules is studied in
order to investigate how chemical compositions are transferred recursively
through cell divisions under replication errors. Depending on the path rate,
the numbers of molecules and species, three phases are found: fast switching
state without recursive production, recursive production, and itinerancy
between the above two states. The number distributions of the molecules in the
recursive states are shown to be log-normal except for those species that form
a core hypercycle, and are explained with the help of a heuristic argument.Comment: 4 pages (with 7 figures (6 color)), submitted to PR
A Physicochemical evaluation of the Compressibility and Dewatering Behavior of Dredged Sediments
The dewatering of low percent solids wastes from tailings ponds, harbors, and waterways presents a challenge in the U.S. and abroad, given the vast amounts that need to be dewatered annually. The United Stated Corps of Engineers estimate about 8.5x109 ft3 of dredged sediments are removed annually in order to keep waterways functional. Dewatering may be achieved with the aid of high strength synthetic textiles, such as geotextiles, which may be sewn lengthwise to form a geotextile tube. Typically, dredged material is mixed with flocculants such as polyacrylamide (PAM), and then pumped into geotextile tubes. In doing so, the flocculants promote aggregation of the particulates, which increases the sedimentation rate and allows for water to drain more freely and quickly through the porous geotextile. The use of geotextile tubes and flocculants are well established in literature and practice, and although many studies have been carried out on sediment-flocculent interactions, few studies have considered role of sediment properties on its interactions with geotextile tubes, sedimentation behavior, compressibility of the sediments, and filtration within the context of geotextile tube dewatering.
In order to gain a more comprehensive understanding of the system, this study characterized 15 dredged sediments from across the U.S. and Canada, and 5 standard materials both chemically (zeta potential, particle charge density, carbon nitrogen ratio, pH, organic content, and cation exchange capacity), and physically (grain size distribution, specific gravity, specific surface area), and then conducted performance tests (sedimentation test, jar tests, centrifuge tests, and pressure filtration) as a way to understand how different sediment properties affect its performance within the context of geotextile tube dewatering. Additionally, the performance tests were conducted using the sediments with and without flocculants (low-, med- high- charge density PAM).
In conducting this study, the chemical properties of the sediments were not found to be prominent indicators of their performance as opposed to the physical parameters. Additionally, the use of flocculants were found to increase the compressibility of the sediments and hasten the dewatering rate, while at the same time slightly increasing the volume of the sediments
On the discrete Peyrard-Bishop model of DNA: stationary solutions and stability
As a first step in the search of an analytical study of mechanical
denaturation of DNA in terms of the sequence, we study stable, stationary
solutions in the discrete, finite and homogeneous Peyrard-Bishop DNA model. We
find and classify all the stationary solutions of the model, as well as
analytic approximations of them, both in the continuum and in the discrete
limits. Our results explain the structure of the solutions reported by
Theodorakopoulos {\em et al.} [Phys. Rev. Lett. {\bf 93}, 258101 (2004)] and
provide a way to proceed to the analysis of the generalized version of the
model incorporating the genetic information.Comment: 15 pages, 12 figure
Стратегическое планирование в высших учебных заведениях
« Les œuvres […] n’existent et ne durent que par l’activité interprétative de leurs publics successifs » Jean-Claude Passeron et Emmanuel Pedler Des inégalités d’accès aux mécanismes de réception Si, à n’en pas douter, l’avènement d’une sociologie des publics de la culture en France a constitué un moment décisif de l’histoire de la discipline, elle ne semble pas être parvenu à élargir son emprise au-delà de la question des déterminants sociaux et du périmètre proposé par la théorie de la lég..
Regulating the Regulators: The Post-Translational Code of Class I HDAC1 and HDAC2
Class I histone deacetylases (HDACs) are cellular enzymes expressed in many tissues and play crucial roles in differentiation, proliferation, and cancer. HDAC1 and HDAC2 in particular are highly homologous proteins that show redundant or specific roles in different cell types or in response to different stimuli and signaling pathways. The molecular details of this dual regulation are largely unknown. HDAC1 and HDAC2 are not only protein modifiers, but are in turn regulated by post-translational modifications (PTMs): phosphorylation, acetylation, ubiquitination, SUMOylation, nitrosylation, and carbonylation. Some of these PTMs occur and crosstalk specifically on HDAC1 or HDAC2, creating a rational “code” for a differential, context-related regulation. The global comprehension of this PTM code is central for dissecting the role of single HDAC1 and HDAC2 in physiology and pathology
Limited profit in predictable stock markets
It has been assumed that arbitrage profits are not possible in efficient
markets, because future prices are not predictable. Here we show that
predictability alone is not a sufficient measure of market efficiency. We
instead propose to measure inefficiencies of markets in terms of the maximal
profit an ideal trader can take out from a market. In a stock market model with
an evolutionary selection of agents this method reveals that the mean relative
amount of realizable profits is very limited and we find that it decays
with rising number of agents in the markets. Our results show that markets may
self-organize their collective dynamics such that it becomes very sensitive to
profit attacks which demonstrates that a high degree of market efficiency can
coexist with predictability.Comment: 4 pages, 4 figure
Communications 71 : Le parti pris du document. Littérature, photographie, cinéma et architecture au XXe siècle. Paris, CETSAH/Seuil, 2001, 463 p.
Ce numéro de Communications offre une pluralité de regards (portés par des écrivains, sociologues, cinéastes, historiens, architectes...) sur la réalité du parti pris du document, tel qu'il peut être livré par la photographie, le film, l'écrit ou l'architecture, à différentes périodes. Plusieurs questions fondamentales sont soulevées, auxquelles sont apportés des éléments de réponse au fil de l'ouvrage. Qu'est-ce qu'informer, documenter, montrer, rapporter les faits réels ? L'objectiv..
Catherine Capdeville-Zeng, Rites et rock à Pékin. Tradition et modernité de la musique rock dans la société chinoise
Catherine Capdeville-Zeng livre une étude monographique de la société du Cercle du rock à Pékin et, à travers elle, entend éclairer l’ensemble de la société chinoise et les oppositions qui la structurent. Se demandant si la Chine est caractérisée par l’idéologie holiste ou par une idéologie individualiste, propre aux sociétés modernes occidentales, l’auteure fait l’hypothèse qu’il existe bien un individu chinois, qui ne serait ni typiquement holiste ni typiquement individualiste, et qu’elle v..
- …