Uden, Holland: A Study of Community and Social Process

Throughout the history of mankind, individuals and all kinds of groups have existed together in localities. We refer to such combinations of individuals and groups as communities. As social units, communities are the focus for study by social scientists of various disciplines. The study of human interaction in the natural laboratory of a community is accomplished by use of the community study method. In this thesis, a case study of the town of Uden, Holland, is presented as an example of how members interacted with one another to foster the continuity of their community. Before presenting the analysis, however, it is necessary first to discuss the nature of communities, the methods for community study, and the ways that this study of Uden demonstrates both of these

Third Cumulant of the total Transmission of diffuse Waves

The probability distribution of the total transmission is studied for waves multiple scattered from a random, static configuration of scatterers. A theoretical study of the second and third cumulant of this distribution is presented. Within a diagrammatic approach a theory is developed which relates the third cumulant normalized to the average, $\langle \langle T_a^3 \rangle \rangle$, to the normalized second cumulant $\langle \langle T_a^2 \rangle \rangle$. For a broad Gaussian beam profile it is found that $\langle \langle T_a^3 \rangle \rangle= \frac{16}{5} \langle \langle T_a^2 \rangle \rangle^2$. This is in good agreement with data of optical experiments.Comment: 16 pages revtex, 8 separate postscript figure

Kinetics of lipase-mediated synthesis of butyl butyrate in n-hexane

This paper reports experimental and modeling work concerning alcoholysis reactions between butanol and ethyl butanoate, catalyzed by Lipozymee in n-hexane, using a batch stirred system at 608C. Description of the reaction kinetics was based on a postulated multisubstrate Ping Pong Bi Bi mechanism, and appropriate rate expressions were derived for all components in the reaction medium. Simplified models were fitted by nonlinear multiresponse regression analysis to data (experimental or calculated from mass balances, as appropriate) encompassing the concentrations of free butanol, ethyl butanoate, ethanol and butyl butanoate. Finally, incremental F-tests were performed to assess the simplest model form that was able to provide a statistically good fit throughout the entire reaction time frame

Comparison of the Role of 5′ Terminal Sequences of Alfalfa Mosaic Virus RNAs 1, 2, and 3 in Viral RNA Replication

AbstractThe 5′ untranslated regions (UTRs) of the genomic RNAs 1, 2, and 3 of alfalfa mosaic virus (AMV) are 100, 54, and 345 nucleotides (nt) long, respectively, and lack extensive sequence similarity to each other. RNA 3 encodes the movement protein P3 and the coat protein and can be replicated in transgenic tobacco plants expressing the replicase proteins P1 and P2 (P12 plants). 5′Cis-acting sequences involved in RNA 3 replication have been shown to be confined to the 5′ UTR. When the 5′ UTR of RNA 3 was replaced by the 5′ UTRs of RNAs 1 or 2, the recombinant RNA was not infectious to P12 plants. Also, when the P3 gene in RNA 3 was put under the control of a subgenomic promoter and the 5′ UTR of this RNA was replaced by 5′ terminal RNA 1 sequences of 103 to 860 nt long or RNA 2 sequences of 57 to 612 nt long, no accumulation of the hybrid RNAs was observed. Deletion of the 5′ 22 nucleotides of RNA 3 resulted in the accumulation of a major progeny that lacked the 5′ 79 nt. However, when the 5′ 22 nucleotides of RNA 3 were replaced by the complete 5′ UTR of RNA 1 or 5′ sequences of RNAs 1, 2, or 3 with a length of 5 to 15 nt, accumulation of the full-length mutant RNAs was observed. The effect of mutations in the 5′ viral sequences of 5 to 15 nt was analyzed. It is concluded that although elements within nucleotides 80–345 of the 5′ UTR of RNA 3 are sufficient for replication, a specific sequence of 3 to 5 nt is required to target the replicase to an initiation site corresponding to the 5′ end of the RNA

Lipase-catalyzed synthesis of butyl butyrate by alcoholysis in an integrated liquid-vapor system

This paper reports experimental work pertaining to alcoholysis between butanol and ethyl butanoate, catalyzed by an immobilized lipase in a liquid-vapor system where chemical reaction and physical separation are simultaneously carried out. The processing setup was tested for various compositions of the starting feedstock and operated under reduced pressure. Samples were withdrawn both from the boiler and the condenser, and they were chromatographically assayed for butyl butyrate. The integrated configuration tested is quite effective toward improvement of the final yield of the desired product

Feedback inhibition enables theta-nested gamma oscillations and grid firing fields

Cortical circuits are thought to multiplex firing rate codes with temporal codes that rely on oscillatory network activity, but the circuit mechanisms that combine these coding schemes are unclear. We establish with optogenetic activation of layer II of the medial entorhinal cortex that theta frequency drive to this circuit is sufficient to generate nested gamma frequency oscillations in synaptic activity. These nested gamma oscillations closely resemble activity during spatial exploration, are generated by local feedback inhibition without recurrent excitation, and have clock-like features suitable as reference signals for multiplexing temporal codes within rate-coded grid firing fields. In network models deduced from our data, feedback inhibition supports coexistence of theta-nested gamma oscillations with attractor states that generate grid firing fields. These results indicate that grid cells communicate primarily via inhibitory interneurons. This circuit mechanism enables multiplexing of oscillation-based temporal codes with rate-coded attractor states

Deviations from the Gaussian distribution of mesoscopic conductance fluctuations

The conductance distribution of metallic mesoscopic systems is considered. The variance of this distribution describes the universal conductance fluctuations, yielding a Gaussian distribution of the conductance. We calculate diagrammatically the third cumulant of this distribution, the leading deviation from the Gaussian. We confirm random matrix theory calculations that the leading contribution in quasi-one dimension vanishes. However, in quasi two dimensions the third cumulant is negative, whereas in three dimensions it is positive.Comment: 9 pages, Revtex, with eps figures,to appear in Phys Rev

Dendritic spine dynamics regulate the long-term stability of synaptic plasticity

Long-term synaptic plasticity requires postsynaptic influx of Ca²⁺ and is accompanied by changes in dendritic spine size. Unless Ca²⁺ influx mechanisms and spine volume scale proportionally, changes in spine size will modify spine Ca²⁺ concentrations during subsequent synaptic activation. We show that the relationship between Ca²⁺ influx and spine volume is a fundamental determinant of synaptic stability. If Ca²⁺ influx is undercompensated for increases in spine size, then strong synapses are stabilized and synaptic strength distributions have a single peak. In contrast, overcompensation of Ca²⁺ influx leads to binary, persistent synaptic strengths with double-peaked distributions. Biophysical simulations predict that CA1 pyramidal neuron spines are undercompensating. This unifies experimental findings that weak synapses are more plastic than strong synapses, that synaptic strengths are unimodally distributed, and that potentiation saturates for a given stimulus strength. We conclude that structural plasticity provides a simple, local, and general mechanism that allows dendritic spines to foster both rapid memory formation and persistent memory storage