cssi/SciSciGPT-SciSciNet huggingface dataset:
Hand-held arthroscopic optical coherence tomography for in vivo high-resolution imaging of articular cartilage

We describe a novel hand-held polarization optical coherence tomographic (OCT) probe that can be inserted into mammalian joints to permit real-time cross-sectional imaging of articular cartilage. The transverse and axial resolutions of the arthroscopic OCT device are roughly 17 and 10 microm, respectively. Two-dimensional cross-sectional images of cartilage tissue with 500 x 1000 pixels covering an area 6 mm in length and 2.8 mm in depth can be acquired at nearly five frames/s and with over 100 dB of dynamic range. Design of an OCT as a hand-held device capable of providing such an optical biopsy of articular cartilage allows eventual in vivo detection of microstructural changes in articular cartilage that are not apparent using conventional arthroscopic cameras. The OCT probe can be easily incorporated in a conventional arthroscope for cartilage site guidance. The optical arrangement in the OCT scope minimizes specular back-reflection of the probe end face and absorption of body fluid in the path and ensures in-focus OCT imaging when it is in contact with the cartilage specimen to be examined. Successful application of in vivo arthroscopy to porcine articular cartilage demonstrates sufficient resolution and practicality for use in human joints.
Fluorescence resonance energy transfer imaging reveals that chemokine-binding modulates heterodimers of CXCR4 and CCR5 receptors.

Background Dimerization has emerged as an important feature of chemokine G-protein-coupled receptors. CXCR4 and CCR5 regulate leukocyte chemotaxis and also serve as a co-receptor for HIV entry. Both receptors are recruited to the immunological synapse during T-cell activation. However, it is not clear whether they form heterodimers and whether ligand binding modulates the dimer formation. Methodology/Principal Findings Using a sensitive Fluorescence Resonance Energy Transfer (FRET) imaging method, we investigated the formation of CCR5 and CXCR4 heterodimers on the plasma membrane of live cells. We found that CCR5 and CXCR4 exist as constitutive heterodimers and ligands of CCR5 and CXCR4 promote different conformational changes within these preexisting heterodimers. Ligands of CCR5, in contrast to a ligand of CXCR4, induced a clear increase in FRET efficiency, indicating that selective ligands promote and stabilize a distinct conformation of the heterodimers. We also found that mutations at C-terminus of CCR5 reduced its ability to form heterodimers with CXCR4. In addition, ligands induce different conformational transitions of heterodimers of CXCR4 and CCR5 or CCR5STA and CCR5Δ4. Conclusions/Significance Taken together, our data suggest a model in which CXCR4 and CCR5 spontaneously form heterodimers and ligand-binding to CXCR4 or CCR5 causes different conformational changes affecting heterodimerization, indicating the complexity of regulation of dimerization/function of these chemokine receptors by ligand binding.
Focus Issue—The Dynamics of Gene Expression

It is gene expression that defines a cell9s identity. Science , Science9s Science of Aging Knowledge Environment (SAGE KE), and Science9s STKE focus attention on the highly dynamic nature of gene expression. Mechanisms governing selective gene expression in multigene families, as well as those by which cis- and trans-acting factors contribute to regulation of gene expression, are topics under discussion. In addition, new methodologies allow researchers to gain insight into gene expression at the level of single cells and provide a glimpse at the real-time interactions among proteins and DNA.
Short peptides self-assemble to produce catalytic amyloids

Enzymes fold into unique three-dimensional structures, which underlie their remarkable catalytic properties. The requirement to adopt a stable, folded conformation is likely to contribute to their relatively large size (>10,000 Da). However, much shorter peptides can achieve well-defined conformations through the formation of amyloid fibrils. To test whether short amyloid-forming peptides might in fact be capable of enzyme-like catalysis, we designed a series of seven-residue peptides that act as Zn(2+)-dependent esterases. Zn(2+) helps stabilize the fibril formation, while also acting as a cofactor to catalyse acyl ester hydrolysis. These results indicate that prion-like fibrils are able to not only catalyse their own formation, but they can also catalyse chemical reactions. Thus, they might have served as intermediates in the evolution of modern-day enzymes. These results also have implications for the design of self-assembling nanostructured catalysts including ones containing a variety of biological and non-biological metal ions.
Shot noise in normal metal d-wave superconducting junctions

We present theoretical calculations and predictions for the shot noise in voltage-biased junctions of d x 2 - y 2 superconductors and normal metal counterelectrodes. In the clean limit for the d-wave superconductor the shotnoise vanishes at zero voltage because of resonant Andreev reflection by zero-energy surface bound states. We examine the sensitivity of this resonance to impurity scattering. We report theoretical results for the magnetic field dependence of the shot noise, as well as the fingerprints of subdominant s- and d x y pairing channels.
Stage-specific control of neuronal migration by somatostatin

Developing neurons transiently express somatostatin and its receptors1,2,3, but little is known about their function at these early stages. As we thought that endogenous somatostatin might control the migratory behaviour of immature neurons, we have examined the effects of somatostatin in cerebellar granule cells of early postnatal mice, because these cells express all five types of somatostatin receptors before the initiation of their migration4,5. Here we show that somatostatin has opposite and stage-specific effects on the migration of cerebellar granule cells. Activation of somatostatin receptors increases the rate of granule cell migration near their birthplace, but decreases the rate near their final destination. Furthermore, somatostatin enhances the size and frequency of spontaneous Ca2+ fluctuations in the early phase of migration, whereas it eliminates spike-like Ca2+ transients in the late phase. Somatostatin-induced changes at both early and late phases are reversed by a blockade of K+ channel activity. These results indicate that somatostatin may provide an essential cue for accelerating the movement of granule cells in the early phase and for terminating the movement in the late phase through altering intracellular Ca2+ concentrations and K+ channel activity.
An approach to establish and evaluate pricing business process in electronic commerce

There are a lot of illogical factors in traditional pricing business process, such as low level of information, automation and poor net, which decrease pricing efficiency, especially in electronic commerce. To solve this problem, traditional pricing business process is analyzed, valued and reengineered with a method of business process quantitative analysis based on process algebra. Then a new pricing business process that is suitable for electronic commerce environment is established according to the principles of business process reengineering and the characteristics of pricing in electronic commerce environment. The evaluation criterions before and after process reengineering are investigated, and the results are satisfied. The results verify that the methods are practical.
Effects of link annotations on search performance in layered and unlayered hierarchically organized information spaces

The effects of link annotations on user search performance in hypertext environments having deep (layered) and shallow link structures were investigated in this study. Four environments were tested ---- layered-annotated, layered-unannotated, shallow-annotated, and shallow-unannotated. A single document was divided into 48 sections, and layered and unlayered versions were created. Additional versions were created by adding annotations to the links in the layered and unlayered versions. Subjects were given three queries of varying difficulty and then asked to find the answers to the queries that were contained within the hypertext environment to which they were randomly assigned. Correspondence between the wording links and queries was used to define difficulty level. The results of the study confirmed previous research that shallow link structures are better than deep (layered) link structures. Annotations had virtually no effect on the search performance of the subjects. The subjects performed similarly in the annotated and unannotated environments, regardless of whether the link structures were shallow or deep. An analysis of question difficulty suggests that the wording in links has primacy over the wording in annotations in influencing user search behavior.
Particle size distribution analysis as a characterization method for gel particles produced in suspension reactors

For gel beads produced in suspension reactors, the properties are usually assumed to be independent of particle size over the range of sizes within a batch. However, differences in equilibrium swelling among different size fractions of particles can be distinguished by analysis of the particle size distributions (PSD) of particles in two different swollen states. The method was proven effective in revealing differences in swelling as a function of size for hydroxypropyl methylcellulose gel beads that were not otherwise apparent. Since solvent sorption controls the useful properties of gels like permeability and is a reflection of gel synthesis variables, the ability to determine variations in properties with particle size is important to predict gel performance or to modify gel synthesis conditions to improve particle uniformity.
Differentiation between hemangiomas and cysts of the liver with nonenhanced MR imaging: Efficacy of T2 values at 1.5 T

The authors studied the utility of non-contrast-agent-enhanced magnetic resonance (MR) imaging for differentiating cysts and cavernous hemangiomas of the liver. Nineteen patients with hemangiomas (51 lesions) and 16 with cysts (30 lesions) were studied with a 1.5-T MR imager. T2 values were calculated with the two-point method to evaluate the efficacy of T2 values in the differentiation between hemangiomas and cysts of the liver. For lesions larger than 1 cm, the mean T2 value of cysts (306 msec +/- 156) was significantly longer than that of hemangiomas (113 msec +/- 15) (P < .0001); there was no overlap of the ranges for T2 values of hemangiomas and cysts. All cysts larger than 1 cm could be differentiated from hemangiomas by using a threshold T2 value of 140 msec. This study suggests that calculated T2 values permit differentiation between hemangiomas and cysts larger than 1 cm at 1.5 T.
A Numerical Study of the Shape of the Surface Separating Flow Into Branches in Microvascular Bifurcations

The shape of the separating surface formed by the streamlines entering the branches of microvascular bifurcations plays a major role in determining the distribution of red blood cells and other blood constituents downstream from the bifurcation. Using the finite element method, we determined the shape of the surface through numerical solution of three dimensional Navier-Stokes equations for fluid flow at low Reynolds numbers in a T-type bifurcation of circular tubes. Calculations were done for a wide range of daughter branch to parent vessel diameter ratios and flow ratios. The effect of Reynolds number was also studied. Our numerical results are in good agreement with previously reported experimental data of Rong and Carr (Microvascular Research, Vol. 39, pp. 186-202, 1990). The numerical results of this study will be used to predict the concentration of blood constituents downstream from microvascular bifurcations providing that the inlet concentration profile is known.
Behavioral manipulations and protein metabolism of the brain: Effects of restricted and enriched environments on the utilization of leucine-H3

Abstract The utilization of systemically injected leucine-H 3 by nerve cells was investigated autoradiographically in rats reared in a restricted and enriched environment. Microdensitometric evaluation of autoradiographic grain density over single nerve cells in several brain regions indicated a significant increase in the utilization of the radiochemical by proteins of the brain in the restricted group of animals. This finding supports the hypothesis that the presumed activation of neuronal circuits by chronic behavioral engagement, represented by the enriched environment, need not lead to enhanced protein metabolism; instead, it is the stress produced by handling and the injection procedure in the previously unhandled, restricted animals that leads under these conditions to increased utilization of the labeled precursor of proteins.
Inactivation of Paenibacillus larvae endospores by a hydrogen peroxide/peroxyacetic acid biocide

(2011). Inactivation of Paenibacillus larvae endospores by a hydrogen peroxide/peroxyacetic acid biocide. Journal of Apicultural Research: Vol. 50, No. 2, pp. 173-175.
The medical-physiological potential of plasma-sprayed ceramic coatings

Abstract In this paper selected literature and experiments performed at the University of Illinois pertaining to the potential use of plasma-sprayed ceramic-coated metal systems as implant materials are reviewed. The nature of the coating-substrate bond is discussed. Adhesive and/or cohesive failure with regard to alumina-coated type 316L stainless steel and Ti-6Al-4V ELI substrates in physiological media is treated as a rate process. The issue of biocompatibility is addressed. Strategies for overcoming the problems uncovered are indicated.
A space-efficient on-line method of computing quantile estimates☆

Abstract The task of computing an estimate for the quantile ( ζ q ) for an unknown distribution F (i.e., F ( ζ q ) = q ) is usually performed by the “sample quantile” method, which computes the ⌊ Nq ⌋ + 1 smallest element from the set of N observations, and thus requires that all N samples be retained in memory. This paper introduces a recursive method of estimating ζ q based on the fact that if the terminal nodes of a uniform d -ary tree are assigned random values, independently drawn from a distribution F , then the minimax alue of the root node converges to a specified quantile of F for very tall trees. The new estimate is shown to be almost as precise as that produced by the sample quantile method and, like it, is guaranteed to converge to ζ q when the sample is large for any arbitrary distribution F . However, in contrast to the sample quantile computation the proposed method requires the retention in storage of at most log 2 N representative data points, where N is the number of samples observed in the past. Moreover, the estimate can be updated quickly using an average of 4, and a maximum of 2 log 2 N , comparisons with each new observation.
Expression of recombinant hepatitis C virus non-structural protein 5B in Escherichia coli

The hepatitis C virus (HCV) represents a major public health problem that can produce liver failure and hepatocellular carcinoma in chronically infected patients. Our goal was to express the HCV non-structural protein 5B (NS5B) protein of HCV genotype 1a in Escherichia coli and initiate studies of its role in HCV genomic replication. In this report we demonstrate that a recombinant NS5B protein with an amino terminal sequence of ASMSYSWTG has RNA-dependent RNA polymerase (RDRP) activity. This recombinant enzyme was active in poly(U) polymerase assays and produced template-sized RNA products when globin mRNA was used as a template. The polymerase activity of recombinant NS5B was primer-dependent and was active for at least 60 min of incubation at 30 degrees C. Deletion of the carboxyl terminal region of HCV NS5B resulted in a loss of RDRP activity indicating that the enzymatic activity observed was due to the full-length recombinant enzyme. Recombinant NS5B (RDRP) should assist in understanding the mechanism of HCV replication and the identification of specific enzyme inhibitors.
Solvent Effects on Electronic Coupling between Dialkylamino Groups in Aromatic Diamine Radical Cations

The transition energies (Eop) for the intervalence bands of the radical cations from N,N,N‘,N‘-tetramethyl-p-phenylenediamine, 1,4-bis(9‘-azabicyclo[3.3.1]non-3‘-one-9-yl)benzene, and N,N,N‘,N‘-tetramethyl-4,4‘-diaminobiphenyl have been determined in eleven solvents varying in polarity from chloroform to acetonitrile. Assuming the Marcus−Hush two state model Eop = 2Hop, where Hop is the matrix coupling element between the charge-bearing dialkylamino units of these delocalized systems. Hop is detectably sensitive to solvent, varying 140, 70, and 110 cm-1, respectively. A trend for dependence of Hop on the refractive index of the solvent (n) is observed, Hop increasing slightly as n-1/2 increases. Empirical fit to the observed Hop values suggests that in addition to the n effect, there is quite compound-specific sensitivity to solvent donor number. Sensitivity of H to solvent is of similar magnitude for the localized bis(hydrazine) intervalence cation 22H+, using Hush's method for evaluating H from the char...
Photoinduced Oxidation of Arsenite to Arsenate on Ferrihydrite

The photochemistry of an aqueous suspension of the iron oxyhydroxide, ferrihydrite, in the presence of arsenite has been investigated using attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), X-ray absorption near edge structure (XANES), and solution phase analysis. Both ATR-FTIR and XANES show that the exposure of ferrihydrite to arsenite in the dark leads to no change in the As oxidation state, but the exposure of this arsenite-bearing surface, which is in contact with pH 5 water, to light leads to the conversion of the majority of the adsorbed arsenite to the As(V) bearing species, arsenate. Analysis of the solution phase shows that ferrous iron is released into solution during the oxidation of arsenite. The photochemical reaction, however, shows the characteristics of a self-terminating reaction in that there is a significant suppression of this redox chemistry before 10% of the total iron making up the ferrihydrite partitions into solution as ferrous iron. The self-terminating behavior exhibited by this photochemical arsenite/ferrihydrite system is likely due to the passivation of the ferrihydrite surface by the strongly bound arsenate product.
Myeloma research goes 3D.

In this issue of Blood , Kirshner and colleagues describe the development of an exciting 3-dimensional model system that appears to support in vitro expansion of primary myeloma cells and provides a physiologically relevant platform on which to test the therapeutic efficacy of antimyeloma drugs.
Topological measurement of an A-tract bend angle: effect of magnesium.

Sequences of four to six adenine residues, termed A-tracts, have been shown to produce curvature in the DNA double helix. A-tracts have been used extensively as reference standards to quantify bending induced by other sequences as well as by DNA binding proteins when they bind to their sites. However, the ability of an A-tract to serve as such a standard is hampered by the wide variation of values reported for the amount of bend conferred by an A-tract. One experimental condition that differs in these studies is the presence of divalent cation. To evaluate this effect, a new application of a topological method, termed rotational variant analysis, is used here to measure for the first time the effect of the presence of magnesium ion on the bend angle conferred by an A-tract. This method, which has the unique ability to measure a bend angle in the presence or absence of magnesium ion, demonstrates that magnesium ion markedly increases the bend angle. For example, when measured in a commonly used gel electrophoretic buffer, the bend angle conferred by a tract of six adenine residues increases from about 7° in the absence of magnesium ion to 19° in the presence of 3.9 mM magnesium ion. This quantitative demonstration of substantial magnesium ion dependence has several important implications. First, it explains discrepancies among bend values reported in various previous studies, particularly those employing gel electrophoretic versus other solution methods. In addition, these findings necessitate substantial revisions of the conclusions in a large number of studies that have used A-tract DNA as the bend angle reference standard in comparison measurements. Finally, any such future studies employing this comparison methodology will need to use the same sequence analyzed in the original measurements as well as replicate the original measurement conditions (e.g. ionic composition and temperature).
Modulation of α-synuclein aggregation by the 70 kDa heat shock protein and its various domains

Molecular chaperones assist in maintenance of functional proteome in vivo and represent the first line of defense against protein misfolding and aggregation in the case of protein misfolding disease. The influence of the stress-induced protein Hsp70 on alpha synuclein aggregation, the primary component of Lewy body's involvement in Parkinson's disease, has been notably investigated. We present in this paper, the in vitro characterization of the effect of the constitutively expressed chaperone Hsc70 and its various domains on alpha synuclein aggregation using ThT assay, AFM, DLS and Cell viability assays. The results show that Hsc70 and C-terminal domains studied are able to inhibit the aggregation of alpha synuclein albeit at different rates and this indicating that efficiency the N-terminal ATPase domain is indispensable. We demonstrate the importance of the Hsc70 C-terminal lid for the full action of Hsc70. This lid might be necessary to bind to α-syn monomer and/or small aggregates and then retard the fibril elongation. We show also a reduced cellular toxicity of alpha synuclein in presence of Hsc70 and its domains with different rates.
Creativity and technological learning: the roles of organization architecture and crisis in large-scale projects

Abstract Creativity increasingly takes place in organizational settings best described as large-scale, long-time duration projects. Such projects, directed at the development of complex products such as aircraft, autos and computers, are characterized by high levels of complexity including ambiguity as to the ultimate outcome and design of the product. In developing these types of products, firms design organizational structures that are composed of many multi-functional teams, each responsible for the design of some sub-system of the overall project. Through a process of inductive theory building based on a case analysis of one such organization, we propose that creativity is affected by multiple levels of interdependence. We find that even the best attempts at developing an organizational architecture to handle such complexity are never complete and that periodically crises arise during the design process. These crises are significant events where creativity occurs and new technical knowledge is generated, allowing the organization to realize its project objectives. Although the case analysis centers on the relation of context to creativity, we argue that creativity leads to technological learning, which we define as a form of organizational learning.
A thermodynamic framework for constitutive modeling of time- and rate-dependent materials. Part I: Theory

A general thermodynamic-based framework for deriving coupled temperature-dependent viscoelasticity, viscoplasticity, viscodamage, and micro-damage healing constitutive models for constitutive modeling of time- and rate-dependent materials is presented. Principle of virtual power, Clausius–Duhem inequality, and the principle of maximum rate of dissipation are used to construct this general thermodynamic framework. A micro-damage healing natural configuration is introduced to enhance the continuum damage mechanics theories in modeling the healing phenomenon. This healing configuration can be considered as the extension of the well-known Kachanov’s effective (undamaged) configuration (Kachanov, 1958). The viscoplasticity loading condition is defined from the microforce balance derived directly from the principle of virtual power. Moreover, for the first time, viscoelasticity, viscodamage, and micro-damage healing microforce balances are derived directly from the principle of virtual power. It is also shown that the generalized non-associative plasticity/viscoplasticity theories can be a direct consequence of postulating the principle of virtual power. The emphasis in this paper is placed on the decomposition of thermodynamic conjugate forces into energetic and dissipative components. It is shown that this decomposition is necessary for accurate estimation of the rate of energy dissipation. The energetic components are related to the Helmholtz free energy, whereas the dissipative components are related to the rate of energy dissipation. This thermodynamic framework is used for deriving more comprehensive viscoelastic, viscoplastic, and viscodamage, and micro-damage healing constitutive models.
Survey of neonatologists’ attitudes toward limiting life-sustaining treatments in the neonatal intensive care unit

To understand neonatologists’ attitudes toward end-of-life (EOL) management in clinical scenarios, EOL ethical concepts and resource utilization. American Academy of Pediatrics (AAP) Perinatal section members completed an anonymous online survey. Respondents indicated preferences in limiting life-sustaining treatments in four clinical scenarios, ranked agreement with EOL-care ethics statements, indicated outside resources previously used and provided demographic information. In all, 451 surveys were analyzed. Across clinical scenarios and as general ethical concepts, withdrawal of mechanical ventilation in severely affected patients was most accepted by respondents; withdrawal of artificial nutrition and hydration was least accepted. One-third of neonatologists did not agree that non-initiation of treatment is ethically equivalent to withdrawal. Around 20% of neonatologists would not defer care if uncomfortable with a parent's request. Respondents’ resources included ethics committees, AAP guidelines and legal counsel/courts. Challenges to providing just, unified EOL care strategies are discussed, including deferring care, limiting artificial nutrition/hydration and conditions surrounding ventilator withdrawal.
Quantitative Relationships Between Lipophilic Character and Drug Metabolism

(1972). Quantitative Relationships Between Lipophilic Character and Drug Metabolism. Drug Metabolism Reviews: Vol. 1, No. 1, pp. 1-13.
Reading between the lines: an evaluation of WindowEyes screen reader as a reference tool for teaching and learning

WindowEyes Version 4.1 for Microsoft Windows 95, 98 and ME, was used in conjunction with three full‐text databases frequently accessed by undergraduate students at academic libraries: EBSCO Academic Search Premier, ProQuest Research Library and Lexis‐Nexis Academic Universe. The purpose of this study is to evaluate the accessibility of three widely used academic databases in conjunction with a screen reader, WindowEyes. In addition, this article also discusses general considerations for evaluating and selecting accessibility hardware and software.
Surface structural relaxation of silica glass: a possible mechanism of mechanical fatigue

The mechanical strength of glasses decreases with increasing time of a tensile stress application in the presence of a moist atmosphere. This mechanical fatigue of silica glasses is an important concern when long time usage of a silica glass product is intended, as in the case of silica glass optical fibers. Various different mechanisms of mechanical strength degradation have been proposed but questions still remain. It is proposed here that surface structural relaxation of the glass may be the mechanism of the mechanical fatigue, since the structural relaxation at low temperature produces glasses with lower mechanical strength. Compared with bulk structural relaxation, surface structural relaxation can take place much more rapidly. The kinetics of the surface structural relaxation of silica glass optical fibers (and plates) was investigated using the IR reflection method at various temperatures as a function of water vapor and applied stress. The kinetics of the surface structural relaxation was accelerated by water vapor pressure as well as by applied tensile stress. The results showed that the surface structural relaxation is a possible mechanism of mechanical fatigue.
Stable matching with preferences derived from a psychological model

We study a special case of the Stable Roommates problem in which preferences are derived from a psychological model common in social choice literature. When preferences are 'single-peaked' and 'narcissistic', there exists a unique stable matching, and it can be constructed in O(n) time. We also show how to recognize quickly, when a set of preferences is single-peaked.
Robust microstructures using UV Photopatternable Semiconductor Nanocrystals

We report an approach to produce predefined patterns of quantum dots and multipod nanocrystals using optical lithography for direct writing of films for optoelectronic and electronic devices. To obtain photopatternability, the nanostructures (for example, CdSe, CdTe, and PbSe nanocrystals) were functionalized by incorporation of the functional ligand t-butoxycarbonyl (t-BOC) which has an acid-labile moiety. This change in the surface chemistry results in the ability to photopattern the semiconductor nanocrystals where desired for a number of optoelectronic device geometries. We demonstrate that the ultimate resolution (line width and spacing) of this technique is below 5 μm (the limit of our optical apparatus used for writing).
Age-related decrease in apomorphine modulation of acetylcholine release from rat striatal slices

Release of [3H]acetylcholine ( [3H]ACh) was assessed in striatal slices from mature, middle-aged and senescent Wistar rats 8, 12 and 24 months of age, respectively. There was an age-related decline in basal release of [3H]ACh as a function of age which was correlated with a decline in accumulation of [3H]ACh. However, the most striking finding was the failure of apomorphine to inhibit KCl-induced [3H]ACh release in the senescent (24 months) animals. Striatal dopaminergic receptor losses in senescence apparently produce several subsequent changes in striatal function which ultimately result in the decline of motor-behavioral function.
Thermodynamic and kinetic constraints on reaction rates among minerals and aqueous solutions. III. Activated complexes and the pH-dependence of the rates of feldspar, pyroxene, wollastonite, and olivine hydrolysis

The stoichiometries of activated complexes responsible for controlling the kinetics of mineral dissolution can be inferred from experimental rate data. Constraints are provided by adsorption equilibria, surface ion exchange reactions, and the pH-dependence of the steady-state rates of surface detachment. Adsorption equilibria may lead to accelerated or decelerated rates of hydrolysis due to formation of surface species. They may also result in pH-independent dissolution rates at low pH as a consequence of hydrogen ion surface saturation. Surface exchange reactions of H+ or H3O+ for M(2) site cations in pyroxenes, Ca2+ in wollastonite, and alkali cations in feldspars go essentially to completion for dissolution in solutions that are appreciably undersaturated with respect to the reactant mineral. The rate of surface exchange is proportional to the fraction of exchangeable cations on the reacting surface, which leads to an integrated exponential relation for mass transfer as a function of time. The independence of detachment rates on the degree of surface exchange indicates approximately equivalent formation of activated complexes at both exchanged and unexchanged sites. The degree of hydration or protonation of activated complexes formed from surface species at active sites can be inferred from the dependence of the steady-state hydrolysis rates on pH.
Lifetime prevalence and pseudocomorbidity in psychiatric research.

Context Comorbidity is the rule rather than the exception with psychiatric disorders and is consequently of great interest to both researchers and clinicians. However, many studies of psychiatric comorbidity have been based on lifetime prevalence with mixed-age samples, a practice that (1) biases the assessment of epidemiologic comorbidity and (2) creates the appearance of comorbidity even when disorders are randomly associated. This bias is what we refer to aspseudocomorbidity. Objectives To clarify the source of the problem and to discuss strategies that might be adopted to deal hereafter with lifetime prevalence data. Methods A simulated example is presented to show that even when there is only random association between disorders, there will appear to be nonrandom comorbidity when lifetime prevalence is used with mixed-age samples. An actual example relating psychosis to phobia is presented to show the bias that can result and to illustrate one way of dealing with lifetime prevalence data. Conclusions Use of lifetime prevalence with mixed-age samples, used almost exclusively in psychiatric research, generates problematic results, especially when used for assessment of comorbidity, and should be viewed with some skepticism. Hereafter, we recommend that any future use of lifetime prevalence should require determination of the age of onset, even if only by retrospective report. Comorbidity then should be reported by age.
Aerodynamics of the Mars Microprobe Entry Vehicles

The selection of the unique aeroshell for the Mars Microprobes is discussed. A description of its aerodynamics in hypersonic rarefied, hypersonic continuum, supersonic, and transonic flow regimes is then presented. This description is compiled from Direct Simulation Monte Carlo simulations, computational fluid dynamics, wind tunnel data, and ballistic range data. The aeroshell is shown to possess the correct combination of aerodynamic stability and drag to convert the probe''s initial tumbling attitude at atmospheric-interface into the desired surface-impact orientation and velocity.
Failure of AZT: a molecular perspective.

Biochemical and molecular analyses of the Interaction of AZT monophosphate with thymldylate klnase provide novel Insights Into the limited clinical efficacy of AZT (pages 922–924).
Epidermal Growth Factor Enhances Expression of Connexin 43 Protein in Cultured Porcine Preantral Follicles

Connexin 43 (Cx43) and gap junctional coupling appear to play a critical role in early follicular development because absence of Cx43 disrupts progression of follicles beyond primary stages in transgenic mouse ovaries. Two experimental culture systems were used to determine whether epidermal growth factor (EGF) stimulates expression of Cx43 in early porcine follicular development. Ovarian explants were collected from 32- to 40-day-old gilts and cultured for 6 days on membrane inserts in Waymouth MB 752/1 medium supplemented with 0, 50, or 500 ng/ml mouse EGF. Western blot analysis demonstrated significant increases (P < 0.05) in relative amounts of Cx43 protein (both phosphorylated and nonphosphorylated) with 50 and 500 ng/ml of EGF as compared with control cultures. Preantral follicles were enzymatically isolated from 70- to 86-day-old gilts and cultured for 8 days in collagen matrices. Medium and EGF treatments were the same as previously described. Western blot analysis demonstrated a significant increase (P < 0.05) in relative amounts of Cx43 protein with 50 and 500 ng/ml of EGF as compared with control cultures. EGF increased expression of Cx43 protein in secondary preantral follicles in a dose-dependent manner, which suggests that EGF or similar growth factor molecules may modulate early folliculogenesis by stimulating expression of Cx43 gap junctions.
The potential energy functions of idealized models of fixed charge and dipole distributions as related to surface chemical phenomena

Abstract The potential energy functions are derived of idealized electrostatic models of fixed charge and dipole distributions on a surface of finite dimensions. The graphs of these functions when compared with the similar functions for a point charge, a point dipole, and a value of kT indicate that it is possible that long range (distances > 100 A) interactions may occur between surfaces and macromolecules in solution.
Succinct representation of regular languages by boolean automata II

Abstract Boolean automata are a generalization of finite automata in the sense that the next state (the result of the transition function, given a state and a letter) is not just a single state (deterministic automata) or a set of states (nondeterministic automata) but a boolean function of the states. Boolean automata accept precisely the regular languages; also, they correspond in a natural way to certain language equation involving complementation as well as to sequential networks. In a previous note we showed that for every n ⩾ 1, there exists a boolean automaton B n with n states such that the smallest deterministic automaton for the same language has 2 2 n states. In the present note we will show a precisely attainable lower bound on the succinctness of representing regular languages by boolean automata; namely, we will show that, for every n ⩾ 1, there exists a reduced automaton D n with n states such that the smallest boolean automaton accepting the same language has also n states.
Plasmoid observations in the distant plasma sheet boundary layer

Substorm associated large amplitude bipolar magnetic events occurred when ISEE 3 was in the distant geotail's plasma sheet boundary layer (PSBL). The characteristics of these events, their substorm association and their possible source mechanisms are examined. We propose that these PSBL events are signatures of a passing plasmoid in the plasma sheet, analogous to the traveling compression region model in the geomagnetic lobes.
Fludarabine Allows Dose Reduction for Total Body Irradiation in Pediatric Hematopoietic Stem Cell Transplantation

Purpose: To examine, in the setting of total body irradiation (TBI) for the preparation of pediatric hematopoietic stem cell transplantation (HSCT), whether TBI dose can be reduced without compromising the efficacy of a regimen consisting of fludarabine and radiotherapy; and whether there is any increased risk of pulmonary toxicity due to the radiosensitizing effect of fludarabine. Methods and Materials: A total of 52 pediatric patients with hematologic malignancies received TBI-based conditioning regimens in preparation for allogeneic HSCT. Twenty-three patients received 12 Gy in 4 daily fractions in combination with cyclophosphamide, either alone or with other chemotherapeutic and biologic agents. Twenty-nine patients received 9 Gy in 3 fractions in conjunction with fludarabine and melphalan. Clinical and radiation records were reviewed to determine engraftment, pulmonary toxicity (according to Radiation Therapy Oncology Group criteria), transplant-related mortality, recurrence of primary disease, and overall survival. Results: The two groups of patients had comparable pretransplant clinical characteristics. For the 12-Gy and 9-Gy regimens, the engraftment (89% and 93%; p = 0.82), freedom from life-threatening pulmonary events (65% and 79%; p = 0.33), freedom from relapse (60% and 73%; p = 0.24), and overall survival (26% and 47%; p = 0.09) were not statistically different. Conclusions: The addition of fludarabine and melphalan seems to allow the dose of TBI to be lowered to 9 Gy without loss of engraftment or antitumor efficacy.
The psychological causality implicit in language

We are concerned with the causality implicit in English verbs that name interactions, either mental or behavioral, between two persons, verbs such as like, notice (mental), and help, cheat (behavioral) in such a context as Ted—Paul. Using four different methods, we show that adult native speakers think of causality in such verbs as unequally apportioned between interactants. For behavioral (or action) verbs greater causal weight is given to the Agent argument of the verb (e.g., Ted in Ted helps Paul) than to the Patient argument (Paul). For mental (or state) verbs greater causal weight is given to the Stimulus argument of the verb (e.g., Paul in Ted likes Paul) than to the Experiencer argument (Ted). For English verbs of the type studied, derivational adjectives often exist (e.g., helpful, cheating, likable, noticeable). Such adjectives are attributive to one or the other argument of the verb base (Agent or Patient; Stimulus or Experiencer). We show that the direction of causal attribution in the adjective (e.g., helpful is attributive to Ted the Agent; likable is attributive to Paul the Stimulus) predicts the primary causal weightings assigned in our experimental tasks. We also show that in the English language adjectives derived from action verbs are almost attributive to the Agent and adjectives derived from state verbs to the Stimulus. Because certain facts about English morphology predict certain ways of thinking about causality, our main finding may seem to be a Whorfian one, a demonstration that language affects thought. However, we argue that it is not that but rather a demonstration that two modes of thought (the Agent-Patient Schema and the Stimulus-Experiencer Schema) affect language use. We suggest that the schemas are universals of human thought.
Seed Germination and Reproductive Strategies in Federally Endangered Harperella (Harperella nodosum Rose, Apiaceae)

ABSTRACT Harperella (Harperella nodosum) is a federally endangered plant with 26 known sites in the southeastern United States. Experiments in the greenhouse and observations in the wild demonstrated that harperella is an annual plant and its seeds can germinate immediately after seed maturation under warm-weather conditions in late summer. Harperella was observed to utilize two complementary reproductive strategies as important adaptations to survival in a frequently flooded, semiaquatic habitat, depending on flooding frequency and amplitude: (a) sexual reproduction during low-water years involving flowering and seed production and (b) asexual reproduction during high-water years involving viability of ramets produced at the nodes.
Two-Dimensional Simulation of Platelet Activation in the Hinge Region of a Mechanical Heart Valve

The proper functioning of the leaflets of a bi-leaflet mechanical valve requires the use of the hinge mechanism which lets the leaflets pivot to the valve housing and lets it rotate at a specified angle. It has been pointed that the hinge design directly affects the durability of the valve [1]. In Bi-leaflet valves the thrombus formation is mostly observed in the hinge region and also on the valve housing [2]. This may be due to the complex geometry presented by the hinge region, which makes the flow complex making the hinge region a potential site for thrombus formation and accumulation which could pose a threat to the efficient functioning of the valve itself. It was hypothesized that the flow fields with in the hinge region played a major role in thrombus accumulation in the Medtronic parallel valve [3]. Studies have demonstrated that fluid dynamics in the vicinity of valve leaflet and housing at the instant of valve closure may lead to large negative pressure transients across the leaflets [4]. These large pressure gradients present for a small duration of time induces very high velocity squeezed flow through the clearance region between the valve housing and the leaflet tip and through the gaps in the hinge region which has been provided for rotation of the leaflet and washout. The wall shear stress in these regions can be relatively high during the closure phase resulting in platelet activation. This study will focus on the flow through the hinge region and its effect on the platelet activation during the valve closure under Mitral conditions which is the harshest environment for a valve.Copyright © 2007 by ASME
Severe rectal complications after prostate brachytherapy

Abstract Purpose Some investigators have reported severe rectal complications after brachytherapy. Due to the low number of such events, their relationship to dosimetric parameters has not been well characterized. Methods and materials A total of 3126 patients were treated with low dose rate brachytherapy from 1998 through 2010. 2464 had implant alone, and 313 had implant preceded by 44–46Gy supplemental external beam radiation (EBRT). Post-implant dosimetry was based on a CT scan obtained on the day of implant, generally within 30min of the procedure. Every patient's record was reviewed for occurrence of rectal complications. Results Eight of 2464 patients (0.32%) treated with brachytherapy alone developed a radiation-related rectal fistula. Average prostatic and rectal dose parameters were moderately higher for fistula patients than for patients without a severe rectal complication. For instance, the average R100 was 1.2±0.75cc for fistula patients, versus 0.37±0.88cc for non-fistula patients. However, the fistula patients' values were well within the range of values for patients without a rectal complication. Four patients had some attempt at repair or reconstruction, but long-term functional outcomes were not favorable. Conclusions Rectal fistulas are a very uncommon potential complication of prostate brachytherapy, which can occur even in the setting of acceptable day 0 rectal doses. Their occurrence is not easily explained by standard dosimetric or clinical factors.
Clinical, metabolic and endocrinologic effects of abrupt cessation of maintenance cortisone acetate therapy in rheumatoid arthritis.

Three patients with rheumatoid arthritis who had been maintained on cortisone treatment for periods of at least two and one-half years, were subjected to detailed clinical and metabolic study immediately prior to and following abrupt cessation of cortisone therapy. Clinical manifestations resembling adrenal insufficiency could be differentiated from those of active rheumatoid arthritis. The latter were accompanied by striking sodium retention and evidences of increased plasma volume. Although the symptoms of adrenal insufficiency disappeared four days after stopping cortisone, steroid excretion studies indicated that reduced and abnormal adrenal cortical function persisted for a longer period than this and suggested that this could not entirely be attributed to a failure of pituitary response. Tres patientes con arthritis rheumatoide, qui habeva essite mantenite per un therapia a cortisona durante periodos de al minus duo annos e medie, esseva subjicite a detaliate studios clinic e metabolic ante e post le cessation abrupte del mentionate medication. Manifestationes clinic simile a illos de insufficientia adrenal poteva esser differentiate ab illos de active arthritis rheumatoide. Iste ultimes esseva accompaniate de marcate grados de retention de natrium e evidentia de augmentos del volumine de plasma. Ben que le symptomas de insufficientia adrenal dispareva quatro dies post le cessation del curso de cortisona, studios del excretion de steroides indicava que le reduction e anormalitate del function adreno-cortical persisteva plus longemente. Le datos suggereva que iste phenomeno non esseva integremente attribuibile al disfallimento del responsa pituitari.