cssi/SciSciGPT-SciSciNet huggingface dataset:
Cell commitment and differentiation in explants of embryonic rat neural retina. Comparison with the developmental potential of dissociated retina

Abstract The differentiation of presumptive neural retina following its isolation from rat embryos and growth in explant and monolayer culture has been studied to obtain information regarding the extent to which factors extrinsic and intrinsic to the retina participate in determining molecular and cytological differentiation. Explanted retinal epithelium retained the capacity for mitosis, as shown by [3H]thymidine incorporation, and from the undifferentiated neuroepithelium, retinal cell-types emerged and acquired a laminar organization resembling that in vivo. Characterization of rod photoreceptor cells at both the light and electron microscopic level showed that these cells exhibit differentiated structural features including inner segments, connecting cilia and membranous expansions suggestive of forming outer segments. Immunofluorescent labeling with an antibody to a synaptic vesicle protein, and electron microscopic identification of synaptic elements showed formation of synapses by the photoreceptor cells within the explant. Neurites extending from the explants exhibited growth on laminin, fibronectin and collagen substrates. Since the neurites immunolabeled with antibodies to the 140 kDa subunit of neurofilament and with antibodies to Thy-1, they could be identified as axons of ganglion cells. Antibodies to a variety of cell-type specific antigens showed that the cells expressed molecules associated with the fully differentiated cell. Furthermore, since our approach has been to explant embryonic retina at an age when the antigens are not yet expressed in vivo, the appearance of the antigens in culture represented de novo expression. In contrast, neural retinal cells in dissociated cultures did not exhibit de novo expression of differentiated molecular properties. Collectively, these results indicate that the isolated neural retina is capable of cell birth, commitment and differentiation when the cells are maintained together in explant culture, whereas the environment of monolayer cultures is apparently unable to promote the generation of mature neuronal phenotypes.
Recording shift-selective volume holograms in bacteriorhodopsin

The application of volume M-type holograms for building multichannel geometries in pattern recognition system is considered. The results of theoretical and experimental investigations of the hologram's parameters as a function of their recording parameters and their use as filters in correlation setups are presented. Multichannel correlation schemes where the processed signals have either different or the same wavelength are proposed. We have shown that all the correlation schemes proposed allow one to increase data throughput several times over single- channel BR-based correlators.
Scaling dynamics for solvable coagulation equations with dust and gel

We study limiting behavior of rescaled size distributions that evolve by Smoluchowski's rate equations for coagulation, with rate kernel K=2, x+y or xy. We find that the dynamics naturally extend to probability distributions on the half-line with zero and infinity appended, representing populations of clusters of zero and infinite size. The “scaling attractor” (set of subsequential limits) is compact and has a Levy-Khintchine-type representation that linearizes the dynamics and allows one to establish several signatures of chaos. In particular, for any given solution trajectory, there is a dense family of initial distributions (with the same initial tail) that yield scaling trajectories that shadow the given one for all time. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Divalent copper trans-1,4-cyclohexanedicarboxylate coordination polymers with isomeric dipyridylamide ligands: new pillared and self-penetrated binodal networks

Hydrothermal synthesis has afforded a pair of divalent copper coordination polymers containing trans-1,4-cyclohexanedicarboxylate (t-14cdc) and one of two isomeric dipyridylamides, 3-pyridylnicotinamide (3-pna) or 3-pyridylisonicotinamide (3-pina). Both of these materials feature unprecedented 3-D topologies. [Cu(t-14cdc)(3-pna)]n (1) manifests [Cu(t-14cdc)]n 4·82 layers featuring embedded anti–syn axial–equatorial bridged [Cu(OCO)]n chain motifs, pillared by anti-conformation 3-pna ligands into a new yet very simple binodal 3,5-connected (4·6·8)(4·66·83) network topology. {[Cu2(t-14cdc)2(3-pina)2(H2O)]·5H2O}n (2) shows two different copper/t14cdc chain motifs with isolated copper ions and {Cu2O2} dimeric units, respectively. These are linked together by 3-pina ligands to afford a new self-penetrated 4,6-connected binodal net with (4·64·8)2(42·612·8) topology. Variable temperature magnetic susceptibility experiments reveal very weak ferromagnetism (g = 2.01(1), J = 0.04(1) cm−1) along the [Cu(OCO)]n chains in 1 and weak antiferromagnetism (g = 1.906(3), J = −3.4(3) cm−1) within the {Cu2O2} dimeric units in 2. Thermal properties are also presented.
Renewable Hydrogen Carrier - Carbohydrate: Constructing the Carbon-Neutral Carbohydrate Economy

The hydrogen economy presents an appealing energy future but its implementation must solve numerous problems ranging from low-cost sustainable production, high-density storage, costly infrastructure, to eliminating safety concern. The use of renewable carbohydrate as a high-density hydrogen carrier and energy source for hydrogen production is possible due to emerging cell-free synthetic biology technology—cell-free synthetic pathway biotransformation (SyPaB). Assembly of numerous enzymes and co-enzymes in vitro can create complicated set of biological reactions or pathways that microorganisms or catalysts cannot complete, for example, C6H10O5 (aq) + 7 H2O (l) a 12 H2 (g) + 6 CO2 (g) (PLoS One 2007, 2:e456). Thanks to 100% selectivity of enzymes, modest reaction conditions, and high-purity of generated hydrogen, carbohydrate is a promising hydrogen carrier for end users. Gravimetric density of carbohydrate is 14.8 H2 mass% if water can be recycled from proton exchange membrane fuel cells or 8.33% H2 mass% without water recycling. Renewable carbohydrate can be isolated from plant biomass or would be produced from a combination of solar electricity/hydrogen and carbon dioxide fixation mediated by high-efficiency artificial photosynthesis mediated by SyPaB. The construction of this carbon-neutral carbohydrate economy would address numerous sustainability challenges, such as electricity and hydrogen storage, CO2 fixation and long-term storage, water conservation, transportation fuel production, plus feed and food production.
Model-based prediction of phalanx radiograph boundaries

In this study we use a strong model of the center of the phalanx in hand radiographs to predict continuation of the phalanx boundary. The center phalanx is robustly segmented using conventional approaches. Estimating tangents allows us to find the minimum width of the phalanx by parallel tangent lines. This in turn predicts the phalanx 'center'. The phalanx boundaries are modeled as cubic splines, and the coronal cross-section is modeled as a hemi- ellipse. Using initial localization from the phalanx center and the above parametric models, the model of radiographic imaging is used to predict the continuation of the boundary. Results are shown for least squared error of model spline fits to continuation of the phalanx boundary anchored by initial match on the center of the projected phalanx.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
The dynamic behavior of CheW from Thermotoga maritima in solution, as determined by nuclear magnetic resonance: implications for potential protein–protein interaction sites

Measurements of the 15N relaxation parameters have been used to characterize the backbone dynamics of CheW from Thermotoga maritima. The dynamic nature of residues that appeared disordered in our recent solution structure of CheW is confirmed by these dynamics measurements. We have interpreted the data in terms of the Lipari and Szabo 'model-free' approach. The derived order parameter, S(2), the [1H]-(15)N heteronuclear nuclear Overhauser effect (NOE) values, the chemical exchange rate, R(ex), and the internal correlation time, tau(e), show that CheW exhibits considerable motional freedom from the picosecond to millisecond time scales. These regions of the protein cluster within the framework of the three-dimensional structure and may indicate possible binding sites for other protein components of the bacterial chemotaxis receptor-signaling complex. The structure of CheW consists of two five-stranded beta-barrel domains that pack together with an extensive hydrophobic core between the domains. Regions highlighted by dynamics measurements co-localize to specific regions of the three-dimensional structure of CheW previously implicated in the formation of bacterial chemotaxis receptor signaling complex. The motional properties of domain 2 of CheW suggest that this domain may be able to experience structural rearrangements that allow the exposure of a hydrophobic surface area that could be used as a binding surface for the other members of the receptor complex. Residues within domain 2 have been implicated in binding interactions for two chemotaxis proteins, CheA and the receptor. We further propose that domain 1 interacts with other components of the chemotaxis machinery, such as CheZ, or in the formation of clusters of signaling components.
Surgery for appendicitis: is it necessary?

ABSTRACT Background: Appendectomy for acute appendicitis is an effective, universally accepted procedure performed more than 300,000 times annually in the United States. It is generally believed that appendicitis progresses invariably from early inflammation to later gangrene and perforation, and that appendectomy is required for surgical source control. Although non-operative management with antibiotics of uncomplicated diverticulitis, salpingitis, and neonatal enterocolitis is now established, the non-operative management of appendicitis remains largely unexplored. Methods: Systematic review of published literature and derived expert opinion. Results: Clinical, epidemiologic, radiologic, and pathologic evidence is presented for spontaneous resolution of uncomplicated acute appendicitis. The pathogenesis of appendicitis is reviewed with specific consideration of the role of bacterial infection in the pathogenesis. Evidence is also provided documenting the clinical success of non-operative management. Con...
Growth and Development

The purpose of this chapter is to explore the origins of tourism as a subject of study and to examine and explain the ways in which it has developed over the last 40 years or so. The chapter draws particularly on the experience of the UK, which is where some of the earliest programmes developed and to that extent it provides a national perspective. However, the issues and patterns that it presents are replicated, often with different timescales, in many other parts of the world.
Multiplex holography for space-variant processing: a transfer function sampling approach

Several techniques for the holographic representation of any bandlimited space-variant system by spatially sampling the input plane and multiplexing the respective system transfer functions have been previously described. This paper describes an alternative multiplexing technique in which the transfer functions are sampled in the Fourier plane to produce the multiplexed holograms. Various techniques for generating multiple copies of the input function that are required during playback are considered. Experimental results using computer-multiplexed holograms are also presented.
Freezing on a finned tube for either conduction-controlled or natural-convection-controlled heat transfer

Abstract Experiments were performed to study freezing on a finned vertical tube when either conduction in the solid or natural convection in the liquid controls the heat transfer. Conduction is the controlling mode when the liquid is at its fusion temperature, whereas natural convection controls when the liquid temperature is above the fusion value. The phase change medium was a paraffin, 99% pure n-eicosane, with a fusion temperature of 36.4°C. Auxiliary experiments were also performed with an unfinned tube to obtain comparison data. For conduction control, the enhancement of freezing due to finning is less than the area ratio of the finned and unfinned tubes, whereas for natural-convection control the enhancement is very nearly equal to the area ratio. The liquid-solid interface is a thicket of whisker-like crystals when conduction controls but is straight (i.e. vertical). On the other hand, the interface is smooth but tapered when natural convection controls—yielding bottom-heavy frozen specimens. When conduction controls, freezing continues more or less indefinitely, whereas natural convection severely retards the freezing and ultimately terminates it altogether.
Caloric balance, brain to body ratio, and the timing of menarche

Caloric availability regulates female reproductive function. Menses do not normally occur until the amount of stored fat is sufficient to meet the nutritional requirements of pregnancy. Unusual energy drains such as heavy exercise cause a reversible cessation of menses. The brain appears to monitor the balance between the availability of calories and their utilization, and reproduction is suppressed when the balance is unfavorable. We postulate that the juvenile human brain, with its unique metabolic requirements, constitutes an important energy drain in the premenarchal girl, and that caloric utilization by the brain may explain the delay of reproductive competence in man. It follows that the changing energy requirements of the brain relative to the body during normal premenarchal growth may play a key role in the timing of menarche. Pathological examples of altered brain to body ratios support this hypothesis: an increase of the brain to body ratio has been observed to delay menarche, a decrease of the brain to body ratio to advance menarche. We explore several clinical implications of this hypothesis and present suggestions for its experimental evaluation.
The Role of Experience in Prioritizing Adherence to SOPs in Police Agencies

Research has perennially substantiated the belief that experience is a crucial determinant of an officer’s ability to effectively use discretion in making decisions. Officers cite experience as “the best teacher”, and police managers are likely to agree, usually with an anecdote or two about their personal maturation experiences. This study is an attempt to investigate this question with a bit more subtlety. In the following sections, we will: (1) explain the theory behind the discretion-experience relationship we propose, as well as theoretical opposition to this notion, (2) hone in on the perceived importance of agency standard operating procedures as an influence on discretion, (3) demonstrate that the relationship between officer experience and the priority attributed to SOPs is parabolic, and (4) discuss our findings in the context of structural functional organizational theory.
Design Guidelines for Polyethylene Pipe Interface Shear Resistance

Polyethylene pipes are commonly used in pipeline systems. Current methods used to determine the pipe pullout capacity do not consider the effects of diameter changes and cyclic movements that the pipelines may experience. Laboratory tests were performed to study the interface shearing resistance of polyethylene pipes under varying conditions. The tests were performed in a temperature-controlled room, where properties were investigated for thermal variations expected in the field. Two types of tests were performed: pull/push tests and cyclic tests. Test results indicated that reductions in pipe diameter affect the interface shear resistance that develops between the pipe and soil. As the pipe diameter gets smaller, the normal contact stresses at the interface decreases, causing a reduction in the interface shearing resistance directly proportional to the normal stress changes. Cyclic pipe movements also cause significant reduction in pipe pullout resistance. The test results indicated that the polyethylene...
The extraterrestrials are coming

Abstract A number of systems using communications satellites to provide telephone and data services are reviewed and compared in terms of their features and orbital characteristics. Analyses are performed of their technological, financial, market and regulatory aspects. The conclusion is that the many low Earth-orbit systems have a very doubtful future.
Experimental and Theoretical Study of 1,5‐Diamino‐4‐H‐1,2,3,4‐Tetrazolium Perchlorate

Abstract : The synthesis and characterization of 1 ,5-diamino- 1,2,3 ,4-tetrazolium perchlorate were carried out. Experimental evidence strongly supports the protonation of a nitrogen atom of the tetrazole ring, including the structure observed in a single crystal x-ray diffraction study of the title compound. Quantum chemical calculations were performed at the CCSD(T)/6-311G(2df,p)//MP2/6-311G(d,p) level of theory to determine the relative energies of all possible N-protonated structures of the 1,5.-diamino- 1,2,3,4-tetrazole ring. The predicted geometry of the most stable isomer compares favorably with the experimentally observed structure.
Rotational period of comet Halley

Results are reported from ground-based photometric measurements of the variations in Comet Halley emissions at different wavelengths in order to calculate the comet rotation rate. The data, gathered at Cerro Tololo, included the OH, NH, CN, C3, CO(+) and C2 bands and continuum emissions at 3650 and 4845 A. Emphasis is placed on the C2 data at 5140 A. Both a periodic variation and a secular decrease was detected through March-April 1986. Light curves generated with the data support a rotational period just short of 7.4 days.
Coralline hydroxyapatite as an ocular implant

Fifty patients received a coralline hydroxyapatite sphere as a buried integrated ocular implant after enucleation or evisceration surgery. The surgical technique is described and the results discussed. All patients obtained final prosthetic motility superior to that possible with simple spherical methylmethacrylate implants. After a follow-up of 2 to 27 months (mean, 10.4 months) there have been no cases of migration or extrusion. Complications have been minimal and easily managed. The hydroxyapatite implant appears to offer excellent cosmetic reconstruction without the unacceptable infection and extrusion rates seen with other integrated implants.
Activation of factor VIII by thrombin increases its affinity for binding to synthetic phospholipid membranes and activated platelets.

Membrane-bound thrombin-activated factor VIII (fVIIIa) functions as a cofactor for factor IXa in the factor Xase complex. We found that binding of heterotrimeric fVIIIa (A1.A2.A3-C1-C2) to synthetic vesicles with a physiologic content of 4% phosphatidylserine (PS), 76% phosphatidylcholine, and 20% phosphatidylethanolamine occurs with a 10-fold higher affinity than that of factor VIII (fVIII). The increased affinity of fVIIIa for PS-containing membranes resulted from the reduced rate of fVIIIa dissociation from the vesicles compared with that of fVIII. Similar affinities of A3-C1-C2, A1.A2. A3-C1-C2, and A3-C1-C2.heavy chain for interaction with PS-containing membranes demonstrate that removal of the light chain (LCh) acidic region by thrombin is responsible for these increased affinities of fVIIIa and its derivatives. Similar kinetic parameters of fVIII and its LCh and C2 domain for binding to PS-containing membranes and to activated platelets indicated that the C2 domain is entirely responsible for the interaction of fVIII with membranes. We conclude that the increased fVIIIa affinity for PS-containing membranes is a result of conformational change(s) within the C2 domain upon removal of the acidic region of the LCh. This conclusion is based on the finding that binding of the monoclonal antibody ESH8 to the C2 domain, which is known to prevent this conformational transition, resulted in fVIIIa binding to PS/phosphatidylcholine/phosphatidylethanolamine vesicles (4/76/20) with a lower affinity similar to that of fVIII. In addition, stabilization of the low affinity binding conformation of the C2 domain of fVIIIa by this antibody led to an inhibition of the fVIIIa activity in the factor X activation complex.
The co-evolution of knowledge and event memory

We present a theoretical framework and a simplified simulation model for the co-evolution of knowledge and event memory, both termed SARKAE (Storing and Retrieving Knowledge and Events). Knowledge is formed through the accrual of individual events, a process that operates in tandem with the storage of individual event memories. In 2 studies, new knowledge about Chinese characters is trained over several weeks, different characters receiving differential training, followed by tests of episodic recognition memory, pseudo-lexical decision, and forced-choice perceptual identification. The large effects of training frequency in both studies demonstrated an important role of pure frequency in addition to differential context and differential similarity. The SARKAE theory provides a framework within which models for various tasks can be developed; we illustrate the way this could operate, and we make the verbal descriptions of the theory more precise with a simplified simulation model applied to the results.
Structure-activity relationships for the in vitro hematotoxicity of N-alkoxyacetic acids, the toxic metabolites of glycol ethers☆

Ethylene glycol mono-n-alkyl ethers are a major class of industrial chemicals which cause a wide range of toxic effects in laboratory animals including reproductive and developmental toxicity, as well as hematotoxicity. Alkoxyacetic acids are the major metabolites of ethylene glycol ethers and are considered to be the proximate toxic metabolites. The structure-toxicity relationships of these acids are well documented in the reproductive and developmental systems. Therefore, current studies were conducted to investigate the structure-activity relationships of these acids for hematotoxicity in rat blood in vitro. Results presented here indicate that the effects of various alkoxyacetic acids on rat erythrocytes are qualitatively similar and comprise early swelling followed by hemolysis. The ranking of the activity of these acids was as follows: butoxyacetic acid (BAA)>propoxyacetic acid ≅ pentoxyacetic acid > ethoxyacetic acid>methoxyacetic acid. Furthermore, this effect of alkoxyacetic acids was associated with a parallel decrease in blood ATP levels. It is currently unknown if swelling or ATP depletion is the primary effect of these acids. In addition, at equimolar concentrations neither heptanoic, butoxypropionic, nor propoxypropionic acids caused any significant effect on rat erythrocytes in vitro. This suggests that the presence and position of the ether linkage, as it is in BAA, are critical for the development of hematotoxicity. Studies of the relationship between the toxic effect of BAA and its partitioning between erythrocytes and plasma showed that the concentration of [14C]BAA in plasma remained relatively constant while that in the erythrocytes increased as a function of time. This pattern of BAA distribution between plasma and erythrocytes was parallel to erythrocyte swelling. Incubation of BAA with rat blood for 30 min followed by removal of BAA by washing the erythrocytes twice and then continuing the incubation revealed that erythrocyte swelling was not reversible, however, the rate of swelling declined significantly.
Game theoretic analysis of a cooperative communication system

We analyze a four node wireless network in which the transmit nodes help each other acting as relays during the periods in which they do not transmit their own information. In order to help the other node, each node has to use a part of its available power. The network is modeled as a non-cooperative game in which each player (node) maximizes its own utility function (information rate). The goal of the game designer (network provider) is to maximize the objective function (in this case the sum rate) in order to get better network efficiency. Here we analyze the so called price of anarchy, as the ratio between the objective function at the worst Nash equilibrium and the optimal objective function. In this scenario, the Nash equilibrium is achieved by selfish (non-cooperative) behavior between the players. In other words, in order to maximize its own utility function each node chooses a strategy to use its available power only for itself, and not helping the other node. Our results show that there is a big possibility for improvement of the sum rate at the Nash equilibrium if the players are ldquoencouragedrdquo to cooperate or to choose a strategy (power policy) that is not selfish. The network operator, therefore, can design a mechanism in which both players maximize their own utilities but also the sum rate at the Nash equilibrium is much closer to the optimal sum rate.
Mechanism based protein crosslinking of domains from the 6-deoxyerythronolide B synthase.

Abstract The critical role of protein–protein interactions in the chemistry of polyketide synthases is well established. However, the transient and weak nature of these interactions, in particular those involving the acyl carrier protein (ACP), has hindered efforts to structurally characterize these interactions. We describe a chemo-enzymatic approach that crosslinks the active sites of ACP and their cognate ketosynthase (KS) domains, resulting in the formation of a stable covalent adduct. This process is driven by specific protein–protein interactions between KS and ACP domains. Suitable manipulation of the reaction conditions enabled complete crosslinking of a representative KS and ACP, allowing isolation of a stable, conformationally constrained adduct suitable for high-resolution structural analysis.
Effects of Aerosol Ot on the Phase Separation Temperatures of Methanol/hydrocarbon/water Blends

ABSTRACT Methanol-gasoline blends have been under consideration for use as transportation fuels to help extend the current fuel supply. The use of these blends is limited, in part, because low temperatures and/or the presence of dissolved water can lead to phase separation. In this work, the effects 1 to 5 % w/v of a model twin-tailed surfactant, Aerosol OT (sulfosuccinic acid, bis[2-ethylhexyl] ester, [577-11-7]), on the phase separation temperature of a simulated gasoline-methanol fuel mixture doped with 0.1, 0.2, and 0.3% v/v dissolved water was studied. The Aerosol OT did lower the phase separation temperature substantially though not as much as straight chain surfactants examined in earlier work.
Barrier-fronted saltponds (Cape Cod, USA) and limans (NW Black Sea, Ukraine): Comparative morphostratigraphy and response to sea-level rise

Abstract Microtidal saltponds of the upper Cape Cod (MA, USA) and the limans of the non-tidal northwestern Black Sea are compared on the basis of their planimetric and barrier-stratigraphic characteristics. The shore-normal ellipticity value ( e n ) is defined as a means of distinguishing between shore-normal (valley-type) and shore-parallel (lagoon-type) trending water bodies, in addition to quantifying their overall morphology. Besides the differences in morphological response to relative sea-level rise of the bays with different e n values (greater impact of barrier retreat on bays with lower e n ), the size of the water bodies and barrier width and height are important factors in determining their response. Given simple landward barrier translation, an average liman with e n =−0.8 will have a 50% reduction in open-water area over approximately 1000 years, whereas less than 10% decrease is predicted for valley-type systems ( e n =0.8) over the same time interval. Similar retreat will take place in just 300 years for saltponds. Although relative sea level is rising at a slower rate along the south shore of Cape Cod than along NW Black Sea, it is expected to have a greater impact on saltpond water area reduction due to their smaller sizes and narrower barriers. Engineering structures make it difficult to predict the near-future behavior of individual coastal segments. Storm-driven flooding, overwash, and breaching of narrow and low barrier segments will be the likely morphodynamic response at both sites.
Social Desirability as Related to Convergence of Temporal Speech Patterns

Studies have suggested that the degree of “matching” or convergence of paralinguistic behavior in dyadic communication is related to various personality variables. This investigation sought to dete...
Evaluating levee failure susceptibility on the Mississippi River using logistic regression analysis

Abstract The goal of this investigation was to test the relative importance of geologic, geomorphic, and other physical factors that have led to levee failures through the past century along much of the Mississippi River. Logistic regression analysis assessed site characteristics at levee-failure locations identified in a database of historical levee failures along 685 km of the Middle and Lower Mississippi River (MMR and LMR). Levee site parameters were evaluated using geologic maps, soil survey maps, digital elevation models (DEMs), historic river maps, dredging reports, and field evaluations. Two statistical models were created for each river reach, one with a conservative ≥ 95% significance threshold, and another with a relaxed significance threshold (≥ 80% for the MMR, and ≥ 90% for the LMR). The conservative MMR model identified the presence/absence of channel fills as a significant and primary predictor of levee failures. The liberal MMR model identified several additional significant controls: location on a meander bend, channel width, land-cover type, and intensity of dredging. The conservative LMR model identified location of failure on a meander bend, land-cover type, channel constriction factor, and sinuosity of the channel as significant, while the liberal LMR model added: the presence of borrow pits, channel width, vegetative buffer width, and presence/absence of bank revetment. The results presented here could potentially assist engineers and decision-makers in choosing appropriate locations and designs for levees in the future.
Influence of Solvent on the Electrophoretic Mobility of Polystyrene Latex

Abstract Latices exhibit anomalous electrokinetic behavior. Instead of the expected decrease in mobility with increasing electrolyte concentration, a maximum occurs. Hairy layer models (HLM) and co-ion enrichment models (CEM) offer incomplete explanations for this. In order to understand the underlying mechanisms, electrophoresis and Fourier transform infrared spectroscopy-attenuated total reflection (FTIR-ATR) experiments were conducted using latex suspended in various solvents. Anomalous electrokinetic behavior, previously reported only for aqueous systems, was also observed in methanol. HLM describe electrokinetic behavior for electrolyte concentrations greater than 10-4M. Both solvation and electrical interactions influence hairy layer thickness. FTIR-ATR results suggest that methanol adsorbs onto latex, consistent with HLM. CEM describe electrokinetic behavior over the entire concentration range. FTIR-ATR results suggest that conditions suitable for hydrophobic adsorption exist. Adsorption maxima vary with the solvent in a manner consistent with the site dissociation model. Adsorption constants vary with the solvent, but the chemical components are similar, contrary to postulated hydrophobic adsorption mechanisms. Instead, the electrical component controls solvent effects. Although both models explain the results, the underlying mechanisms need clarification. HLM must consider solvation of the surface. Proposed hydrophobic adsorption mechanisms are incomplete. Further work is needed to understand the physical processes at latex-solvent interfaces.
Relative importance of meridional and zonal sea surface temperature gradients for the onset of the ice ages and Pliocene-Pleistocene climate evolution

Received 12 June 2009; revised 22 December 2009; accepted 13 January 2010; published 23 June 2010. [1] During the early Pliocene (roughly 4 Myr ago), the ocean warm water pool extended over most of the tropics. Subsequently, the warm pool gradually contracted toward the equator, while midlatitudes and subpolar regions cooled, establishing a meridional sea surface temperature (SST) gradient comparable to the modern about 2 Myr ago (as estimated on the eastern side of the Pacific). The zonal SST gradient along the equator, virtually nonexistent in the early Pliocene, reached modern values between 1 and 2 Myr ago. Here, we use an atmospheric general circulation model to investigate the relative roles of the changes in the meridional and zonal temperature gradients for the onset of glacial cycles and for Pliocene‐Pleistocene climate evolution in general. We show that the increase in the meridional SST gradient reduces air temperature and increases snowfall over most of North America, both factors favorable to ice sheet inception. The impacts of changes in the zonal gradient, while also important over North America, are somewhat weaker than those caused by meridional temperature variations. The establishment of the modern meridional and zonal SST distributions leads to roughly 3.2°C and 0.6°C decreases in global mean temperature, respectively. Changes in the two gradients also have large regional consequences, including aridification of Africa (both gradients) and strengthening of the Indian monsoon (zonal gradient). Ultimately, this study suggests that the growth of Northern Hemisphere ice sheets is a result of the global cooling of Earth’s climate since 4 Myr rather than its initial cause. Thus, reproducing the correct changes in the SST distribution is critical for a model to simulate the transition from the warm early Pliocene to a colder Pleistocene climate.
Trends and geographic patterns in drug-poisoning death rates in the U.S., 1999-2009.

Background: Drug poisoning mortality has increased substantially in the U.S. over the past 3 decades. Previous studies have described state-level variation and urban–rural differences in drugpoisoning deaths, but variation at the county level has largely not been explored in part because crude county-level death rates are often highly unstable. Purpose: The goal of the study was to use small-area estimation techniques to produce stable county-level estimates of age-adjusted death rates (AADR) associated with drug poisoning for the U.S., 1999–2009, in order to examine geographic and temporal variation. Methods: Population-based observational study using data on 304,087 drug-poisoning deaths in the U.S. from the 1999–2009 National Vital Statistics Multiple Cause of Death Files (analyzed in 2012). Because of the zero-inflated and right-skewed distribution of drug-poisoning death rates, a two-stage modeling procedure was used in which the first stage modeled the probability of observing a death for a given county and year, and the second stage modeled the log-transformed drugpoisoning death rate given that a death occurred. Empirical Bayes estimates of county-level drugpoisoning death rates were mapped to explore temporal and geographic variation. Results: Only 3% of counties had drug-poisoning AADRs greater than ten per 100,000 per year in 1999–2000, compared to 54% in 2008–2009. Drug-poisoning AADRs grew by 394% in rural areas compared to 279% for large central metropolitan counties, but the highest drug-poisoning AADRs were observed in central metropolitan areas from 1999 to 2009. Conclusions: There was substantial geographic variation in drug-poisoning mortality across the U.S.
Action of rat liver monoamine oxidase on multiple substrates.

Abstract It is concluded that tyramine, tryptamine, phenylethylamine, and probably i -amylamine are attacked by monoamine oxidase of washed rat liver mitochondrial fraction at the same reactive center(s) of the enzyme. In a mixture, each amine at saturation is oxidized relative to its affinity for the enzyme. Relative affinities manifest themselves at microgram concentrations of the substrate.
SS: Germany's federal election in september 2009: Elections in times of duress - Introduction

This paper introduces the special symposium. It provides (1) an overview of the broad campaign themes; (2) introduces several questions pertinent to German electoral politics; (3) highlights the broader theoretical implications of this symposium for the research literature.
Magnetic susceptibility of FeOCl

Abstract Magnetic susceptibility (χ) measurements on FeOCl are reported. The data were obtained on single crystals over the temperature range 7–400 K. A small but distinct singularity at the Neel temperature T N ≈ 84 K was observed; extensive short-range ordering above T N was also evident from these data. The present work suggests that the intrinsic χ ( T ) of FeOCl was masked by magnetic impurities in the two previous χ studies of this compound.
The 2002 legislative election in Cameroon: a retrospective on Cameroon's stalled democracy movement

This paper examines the impressive victory by President Paul Biya and his ruling Cameroon People's Democratic Movement (CPDM) in the 2002 Cameroon legislative election, especially in the light of the near collapse of the regime and the party in 1992, when it almost lost its parliamentary majority. It argues that several factors contributed to this turn of events including the president's skilful use of his power of incumbency to forestall the democratic process, the ineffectiveness of the opposition parties, and the lack of sustained support for genuine democratic change in Cameroon by France and other Western industrialised nations.
Intake differentiation by rats of equimolar sodium chloride and lithium chloride solutions

Sodium chloride solutions have been frequently used in taste-aversion and bait-shyness experiments as taste equivalents or control solutions for lithium chloride toxin. It was demonstrated that rats can readily discriminate between 0.12 M NaCl and equimolar LiCl when both solutions are continuously available in their home cages. Additional work indicated that the learned discrimination was based primarily upon taste cues but that place cues could also be utilized.
A new technique for the numerical simulation of periodic structures including EBGs, FSSs and Metamaterials

This paper describes a newly developed dipole moment (DM) approach, for modeling periodic structures. It is both memory- and time-efficient, and is applicable to arbitrarily shaped elements, whose material properties can also be arbitrary.
Mean value formula for the root vector functions of the Dirac operator

We consider the one-dimensional Dirac operator on an arbitrary interval and obtain a mean value formula for the root vector functions of this operator.
Chemical constraints of groundwater management in the Yucatan peninsula, Mexico☆

Two critical objectives of water management in the Yucatan are: (1) to develop regional groundwater supplies for an expanding population and tourism based on the Mayan archeological sites and excellent beaches; and (2) to control groundwater pollution in a chemically sensitive system made vulnerable by geologic conditions. The Yucatan peninsula is a coastal plain underlain by permeable limestone and has an annual rainfall of more than 1000 mm. Such a setting should provide abundant supplies of water; however, factors of climate and hydrogeology have combined to form a hydrologic system with chemical boundaries that decrease the amount of available fresh water. Management of water resources has long had a major influence on the cultural and economic development of the Yucatan. The Mayan culture of the northern Yucatan developed by extensive use of groundwater. The religion was water-oriented and the Mayan priests prayed to Chac, the water god, for assistance in water management primarily to decrease the severity of droughts. The Spaniards arrived in 1517 and augmented the supplies by digging wells, which remained the common practice for more than 300 years. Many wells now have been abandoned because of serious problems of pollution resulting from the use of a sewage disposal well adjacent to each supply well. The modern phase of water management began in 1959 when the Secretaria de Recursos Hidraulicos (S.R.H.) was charged with the responsibility for both scientific investigations and development programmes for water-supply and sewage-disposal systems for cities, villages and islands.
Determination of organotins in water by micro liquid chromatography–electrospray/ion trap mass spectrometry

Due to the varying toxicity the species of organotins in their widespread applications, it is important for analytical methods to address their speciation. Traditional methods call for the hydrolysis and subsequent derivatization of the organotins before analysis. These methods can be time-consuming, derivatization can be incomplete and high levels of background interference produce difficulties in identification and quantification. The use is described of a non-derivatization and non-hydrolysis micro-liquid chromatography–electrospray/ion trap mass spectrometry for separation and detection of the organotins. Copyright © 1999 John Wiley & Sons, Ltd.
Bolivia, coca, and US foreign policy

‘Source control’ is a major strategy of the US ‘war on drugs’. After describing how such a strategy was implemented in post 1952 Bolivia, this essay concentrates on the period 1982–1992, a decade in which Bolivia was one of the major suppliers of coca and thus a major recipient of US drug eradication/aid programs. The emergence and growth of the cocaine industry in Bolivia is described as a consequence of failed agricultural policies and US foreign policy in Bolivia. This description highlights events in the Chapare, the main coca growing region in Bolivia that has been subject to US intervention through attempts at policy enforcement and drug eradication. The essay concludes that US source control policy does not work; it has neither assisted in the economic recovery of Bolivia nor diminished the availability of illegal drugs. Drugs continue to be a national security issue for the United States, cocaine is readily available on American streets, and Bolivia is on, the brink of civil war. This essay thus raises a number of questions about US intervention in Bolivia specifically, but other regions of the globe more generally, in the name of ‘protecting US interests’.
Transmission electron microscopy of supported molybdenum and vanadium oxides

Transmission electron microscopy has been used to characterize dispersions of molybdena and vanadia on titania and silica supports. When silica spheres of controlled morphology were used as support, the dispersed “monolayer” phase of both oxides could be imaged due to characteristic changes in contrast. In addition to the dispersed phase, we could detect three-dimensional crystallites of V2O5 but in the case of MoO3 only two-dimensional islands were seen. On Degussa P-25 titania, there was no observable contrast change due to the presence of a monolayer of these dispersed oxides. However, exposure to the electron beam caused dramatic changes in the surface texture of the support. Such changes were not seen when blank TiO2 was similarly irradiated. These e-beam induced changes were more pronounced in the vanadia/titania catalysts leading to formation of 1–3 nm clusters of reduced VOx. However, on the MoO3/TiO2 sample, e-beam exposure caused only a pronounced change in texture but no well defined clusters could be detected.
An experimental study of the (Ti-6Al-4V)-xH phase diagram using in situ synchrotron XRD and TGA/DSC techniques

Abstract Hydrogen has been investigated for decades as a temporary alloying element to refine the microstructure of Ti–6Al–4V, and is now being used in a novel powder metallurgy method known as “hydrogen sintering and phase transformation”. Pseudo-binary phase diagrams of (Ti–6Al–4V)–xH have been studied and developed, but are not well established due to methodological limitations. In this paper, in situ studies of phase transformations during hydrogenation and dehydrogenation of (Ti–6Al–4V)–xH alloys were conducted using high-energy synchrotron X-ray diffraction (XRD), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The eutectoid phase transformation of β ↔ α + δ was observed in the (Ti–6Al–4V)–xH alloy via in situ synchrotron XRD at 211 °C with a hydrogen concentration of 37.5 at.% (measured using TGA–DSC). The relationships of hydrogen composition to partial pressure and temperature were investigated in the temperature range 450–900 °C. Based on these results, a partial pseudo-binary phase diagram of (Ti–6Al–4V)–xH is proposed for hydrogen compositions up to 60 at.% in the temperature range 100–900 °C. Using the data collected in real time under controlled parameters of temperature, composition and hydrogen partial pressure, this work characterizes relevant phase transformations and microstructural evolution for practical titanium–hydrogen technologies of Ti–6Al–4V.
Novel 4,4'-diether-2,2'-bipyridine cisplatin analogues are more effective than cisplatin at inducing apoptosis in cancer cell lines.

Abstract The synthesis and characterization of dichloro(4,4′-bis[methoxy]-2,2′-bipyridine)platinum ( 1 ) and dichloro(4,4′-bis[3-methoxy- n -propyl]-2,2′-bipyridine)platinum ( 2 ) are described. As analogues to CDDP, these 4,4′-disubstituted 2,2′-bipyridine complexes exhibit decreased EC 50 values of 10–100 times in cancer cell lines of the lung, prostate, and melanoma with several combinations of complex and cell line less than 10 μM. Flow cytometry data indicate ‘blocks’ of MDA-MD-435 cycle by 1 (G2/M) and 2 (S). Observed cell survival trends in the presence of 1 , 2 under ionizing radiation mimic those of CDDP. Preliminary structure activity relationships are discussed for the 4,4′-substitutions made on the bipyridine ring.
Unauthorized inferences in semistructured databases

In this paper we study the problem of providing controlled access to confidential data stored in semistructured databases. More specifically, we focus on privacy violations via data inferences that occur when domain knowledge is combined with non-private data. We propose a formal model, called Privacy Information Flow Model, to represent the information flow and the privacy requirements. These privacy requirements are enforced by the Privacy Mediator. Privacy Mediator guarantees that users are not be able to logically entail information that violates the privacy requirements. We present an inference algorithm that is sound and complete. The inference algorithm is developed for a tree-like, semistructured data model, selection-projection queries, and domain knowledge, represented as Horn-clause constraints.
Cytochrome P450 2E1 mRNA in the rat prostate: detection and quantitation by competitive reverse transcription and polymerase chain reaction

Cytochrome P450 2E1 plays a pivotal role in the metabolic activation of a wide variety of low molecular weight environmental toxicants and procarcinogens. In the present study, expression of the P450 2E1 gene in the rat prostate gland was quantitated by competitive reverse transcription and the polymerase chain reaction. To assess accurately the induction level of P450 2E1 mRNA in the prostate after pyridine treatment of rats, a recombinant standard RNA was generated that is homologous to the sequence of P450 2E1 mRNA except for an internal deletion of 100 bases. The data indicate that P450 2E1 mRNA is present in the prostate of untreated animals and is induced about four-fold by treatment with pyridine. The results suggest that exposure to certain environmental chemicals and procarcinogens may increase P450 2E1 levels in the prostate gland and thus could enhance formation of reactive, carcinogenic metabolites.