cssi/SciSciGPT-SciSciNet huggingface dataset:
A silent epidemic of environmental metal poisoning

The main objective of this paper is to provoke and stimulate debate on the health effects of long-term, low-level exposure of human populations to toxic metals. Over one billion (10(9)) human guinea pigs are now being exposed to elevated levels of toxic metals and metalloids in the environment. The number of persons suffering from subclinical metal poisoning is believed to be several million. A large portion of the cases are in developed countries but the urban areas of developing countries have become 'hot-spots' of metal pollution, and the populations of such countries are particularly susceptible to environmental toxins. As a global problem, the potential health effects of metallic hazards should be a matter of public health concern, especially if the emissions of toxic metals into the environment continue at the current rate.
A Model of the Ingroup as a Social Resource

Drawing on theories of social comparison, realistic group conflict, and social identity, we present an integrative model designed to describe the psychological utility of social groups. We review diverse motivations that group membership may satisfy (e.g., the need for acceptance or ideological consensus) and attempt to link these particular needs to a global concern for self-worth. We then examine several factors hypothesized to influence an ingroup's utility in the eyes of its members. Attempting to unite our understanding of (a) why groups are needed and (b) what kinds of groups are useful in meeting those needs, a proposed model of the ingroup as a social resource (MISR) suggests that the dimensions of perceived value, entitativity, and identification interact to determine the overall psychological utility of an ingroup. We discuss empirical and theoretical support for this model, as well as its implications for intra- and intergroup attitudes.
Access problems in laparoscopic cholecystectomy: postoperative adhesions, obesity, and liver disorders.

In the decade since the clinical arrival of laparoscopic cholecystectomy, there have been gratifying improvements in imaging technology and instrumentation, and innovative techniques have evolved. Laboratory-simulator devices are available for basic skills exercises and can at least reasonably mimic the appearance of the gallbladder and some other organs or anatomic regions. Unfortunately, there is no satisfactory method to practice dealing with certain structural abnormalities or disease processes. Because of that, some operations will be particularly difficult and the outcomes will be favorable only with careful planning and capable execution. The experiences and skill level of the surgeon can be enhanced by appropriate mental preparation. As a result, the surgeon will have the opportunity to accomplish the task, both laparoscopically and safely, under circumstances that initially were thought to be inappropriate or impossible for laparoscopy.
Identifying network packets across translational boundaries

A translational boundary is any computer network system which performs network address translation in order to act as an intermediary between client requests and server responses. Since boundaries essentially hide networks from the world by acting on their behalf, a sensor monitoring traffic for malicious activity outside of a boundary would attribute the boundary itself as the target of an attack rather than the actual host affected behind the boundary. This challenge is exacerbated inside of tiered network architectures and drives the need for a capability to track network communications across boundaries. While several attempts have been made at addressing this problem space, existing approaches are often difficult to implement or fundamentally problematic. We propose a novel method for tracking communications across boundaries based on the fact that the message being transmitted must remain constant and intact in order for it to be successfully interpreted by a server. The proposed method leverages cryptographic hashing techniques applied towards the application layer payload of network packets from two different perspectives on the network, enabling correlation before and after the packet headers are modified by the boundary. The technique can be implemented atop open source technology on commodity hardware, and provides a stable foundation for building tiered enterprise network architectures with an inherent capability for pinpointing malicious activity.
Ion-surface interactions and electronically stimulated desorption of physisorbed atoms.

Diabatic potential-energy curves for ${\mathrm{Ar}}^{+}$ and ${\mathrm{Kr}}^{+}$ interacting with a metal surface are reported. At intermediate distances, the attractive force is considerably smaller than the classical result for an ion attracted to its image charge. This has a substantial impact on the dynamics of electronically stimulated desorption, and on the Franck-Condon broadening of photoemission lines. Quantum effects on ion motion are considered, and the validity of a classical treatment is discussed.
Some amino acid cobalt(III) complexes containing tetradentate macrocyclic amine ligands

Abstract The preparation and circular dichroism (CD) spectra of a series of complexes of the type trans-[Co([14] aneN 4 )(amH) 2 ] 3+ and trans-[Co(Me 4 [14]teteneN 4 ) (amH) 2 ] 3+ (amH = glycine, S-alanine, S-phenylalanine and S-leucine) are reported. Cis-[Co([14]aneN 4 ) ox]ClO 4 has been prepared and resolved. The optically active complexes trans-[Co([14]aneN 4 )X 2 ] n+ (X = Cl, glycine and S-alanine) were prepared via the oxalato complex. Comparison of CD spectra indicates that the transitions arising from the 1 A 1 → 1 E g (D 4h ) state in particular are influenced by the axial ligand.
Biomechanics of the Porcine Basilar Artery in Hypertension

Hypertension is a significant risk factor for diverse cerebrovascular diseases ranging from stroke to arteriovenous malformations and saccular aneurysms. Our increasing understanding of vascular mechanobiology reveals that changes in mechanical stimuli, such as increased blood pressure, alter basic cellular functions including the production and degradation of extracellular matrix as well as proliferation, migration, and apoptosis. Understanding changes in the biomechanical properties of the vascular wall is fundamental to correlating mechanobiological responses with the altered loads. In this paper, we present the first biomechanical data on a large cerebral artery in terms of the time of development of hypertension in maturity. Specifically, we report rapid changes in both the structural and the material stiffness of the passive basilar artery in a novel aortic-coarctation model of hypertension in the mini-pig. Histological measurements reveal associated increases in fibrillar collagens in the media and adventitia as well as increased smooth muscle in the media. That such dramatic changes occur within 2 weeks of the initiation of hypertension in maturity necessitates a detailed study of the early changes as well as the potential to reverse these changes at later times.
Using Technology-Assisted Instruction and Assessment to Reduce the Effect of Class Size on Student Outcomes in Undergraduate Mathematics Courses

The implementation of online texts, videos, homework, and tests has changed the process of instruction in introductory college mathematics courses. With this change, more of the students’ learning takes place outside of the traditional college classroom and in places such as tutoring centers and dorm rooms. A combination of chi-square tests—for independence with unordered categorical data—and Mann-Whitney two-sample rank-sum tests—for continuous data and ordered categorical data—were used to analyze student outcomes generated from College Algebra and Applied Calculus courses with class sizes ranging from 37 to 129, with common syllabi, homework, quizzes, and tests. These tests showed that medium classes (30–55 students) had little to no benefit over large classes (110–130 students) in student learning and student achievement, with large classes having small to medium positive-effect sizes over medium classes in the area of student satisfaction. The only area in which the small classes had a small positive...
Rotational Excitation of Diatomic Molecules by Electron Impact

Diatomic molecules rotational excitation calculated from electron molecule elastic scattering parameters in fixed nuclei approximation
Residues of Regge Poles in Different Channels

Conservation of the axial-vector current is assumed, together with the soft-$\ensuremath{\pi}$-meson hypothesis and the pole dominance of the vector and the axial-vector current. It is shown that there is a symmetry between the families of the residue functions of Regge poles in the $t$ channel and those in the $u$ channel for the $s$-channel helicity amplitude of the process ${\ensuremath{\rho}}^{+}({h}_{1})+{{A}_{1}}^{+}({h}_{2})\ensuremath{\rightarrow}{\ensuremath{\rho}}^{+}({h}^{\ensuremath{'}})+{{A}_{1}}^{+}({h}^{\ensuremath{'}})$. Here ${h}_{i}$ and ${h}^{\ensuremath{'}}$ are the helicities of the particles $\ensuremath{\rho}$ and ${A}_{1}$, and they are restricted to 1 or -1. The direct relation between this symmetry and a Veneziano-type formula is discussed. A relation between the residues of the $\ensuremath{\rho}$ and ${A}_{2}$ Regge poles is also given for the general helicity case.
Coagulation dynamics of fractal-like soot aggregates

Abstract How the self-preserving distribution for soot aggregate size evolves as the aerosol passes through the transition regime from free molecule to diffusion limited collision dynamics is experimentally studied over the range of fractal dimension from 1.9 ⩽ D f ⩽ 2.5 . To isolate coagulation from the nucleation and surface growth processes that normally coexist in the flame, soot from a premixed ethylene flame is rapidly sampled and cooled, and introduced into a residence time flow tube. At set distances downstream (corresponding to 0.5–20 s) particles are again sampled, diluted, and their size distribution recorded using a differential mobility analyzer (DMA). These measurements show that a self-preserving distribution is quickly established, but its shape varies as a function of the equivalence ratio and height in the flame from which the soot is sampled. A kinetic model based on the Smoluchowski equation, and employing collision kernels modified to describe the motion of fractal-like particles in the transition regime, reproduces very well both the shapes and temporal evolution of the soot size distributions. The model indicates that the fractal dimension decreases from D f = ∼ 2.5 for soot sampled from near the flame front of relatively lean flames ( Φ = 2.0 ) to a more conventional value of D f = 1.9 for heavier sooting flames ( Φ = 2.4 ) . Thermal desorption experiments and measurements of soot effective density suggest that these trends arise from a decrease in the semivolatile content of the soot present in the residence tube.
On Hearing the Word of God

E ACH time through a college course in Bible which I have taught for several years, the importance of a single figure of speech has grown in my mind. The figure of speech is this: God speaks and man listens and obeys. For the Bible the human response to God is to listen and obey, to hear and do. Since man is thus called by God into his service, religious experience is an experience of vocation, of being called, or put under orders, in such fashion that the whole meaning of one's existence consists in the quality of one's response to the orders. This paper is an attempt to understand some aspects of this experience, and of the metaphor which expresses the experience, particularly as we find it in the prophetic writings of the Old Testament. The biblical metaphor of audition stands in sharp contrast to that of vision which occurs frequently in Greek thought and in Oriental religions. To be sure, the Bible also sometimes speaks of seeing God. Isaiah saw God in the temple. Jesus taught that the pure in heart would see God. Paul saw as well as heard on the Damascus road. Conversely, in some documents of Asiatic religion the metaphor of audition is employed. Usage is likewise mixed in such traditional Christian writers as Augustine who describes the relation of man on this earth to God in terms of hearing and doing, but the state of final blessedness in terms of seeing God. But despite the variations and exceptions of usage, what I want to argue is that for theistic or biblical religion 'to hear and do' is normative, while for mystical or pantheistic religion 'to see and enjoy' is normative. Such a distinction corresponds roughly, I think, to the difference between a prophet and a mystic. In a similar way we may contrast religions which aim at contemplation with the biblical faith which involves the primacy of action. The will of God is for the Bible first and fore-
Coupled Stochastic Spatial and Non-Spatial Simulations of ErbB1 Signaling Pathways Demonstrate the Importance of Spatial Organization in Signal Transduction

Background The ErbB family of receptors activates intracellular signaling pathways that control cellular proliferation, growth, differentiation and apoptosis. Given these central roles, it is not surprising that overexpression of the ErbB receptors is often associated with carcinogenesis. Therefore, extensive laboratory studies have been devoted to understanding the signaling events associated with ErbB activation. Methodology/Principal Findings Systems biology has contributed significantly to our current understanding of ErbB signaling networks. However, although computational models have grown in complexity over the years, little work has been done to consider the spatial-temporal dynamics of receptor interactions and to evaluate how spatial organization of membrane receptors influences signaling transduction. Herein, we explore the impact of spatial organization of the epidermal growth factor receptor (ErbB1/EGFR) on the initiation of downstream signaling. We describe the development of an algorithm that couples a spatial stochastic model of membrane receptors with a nonspatial stochastic model of the reactions and interactions in the cytosol. This novel algorithm provides a computationally efficient method to evaluate the effects of spatial heterogeneity on the coupling of receptors to cytosolic signaling partners. Conclusions/Significance Mathematical models of signal transduction rarely consider the contributions of spatial organization due to high computational costs. A hybrid stochastic approach simplifies analyses of the spatio-temporal aspects of cell signaling and, as an example, demonstrates that receptor clustering contributes significantly to the efficiency of signal propagation from ligand-engaged growth factor receptors.
The Amalgamated Copper Company: A Closed Chapter in Corporation Finance

The original constituents of Amalgamated, 388. — Absorption of Boston & Montana and Butte & Boston, 389. — United Copper, 391. — Relations of United Metals, Utah Consolidated, and International Smelting and Refining Company, 392. — Purchase of properties by Anaconda, 395. — Expansion of International; its absorption and dissolution, 397. — Dissolution of Amalgamated, 402. — Conclusions, 406.
Feature subset selection for inferring relative importance of taxonomy

Examining the bacterial or functional differences between multiple habitats/populations/phenotypes plays an important role in making inferences about the roles that the taxonomy and functional profiles can take on in microbial ecology. It is therefore important to the field of comparative metagenomics, using α- & β-diversity, that methods or algorithms can detect the importance of particular subsets of variables that best differentiate the multiple phenotypes in the data. Given todays genomic data deluge efficient methods that can carry out these inferences cannot be understated enough. We assume observations are collected from a multitude of different environments (e.g., males vs. females, control vs. stimulus, etc.), and each observation is comprised of hundreds or thousands of different taxa/functional features (i.e., 16S or whole genome shotgun). Our goal in this work is to examine the role, assumptions, and inferences that feature subset selection can provide the field of microbial ecology and comparative metagenomics. Specifically we examine feature subset selection algorithms using embedded and filter approaches to infer taxa importance on data collected from the human gut microbiome We compare several widely adopted approaches from machine learning including greedy algorithms and l1 regularization methods, as well as some software tools provided with QIIME, on data collected from the American Gut Project and other canonical studies of the human gut microbiome. We find that there are very few OTUs that carry information in regards to predicting the sex of a gut sample, and that Bacteroidetes is quite frequently found in the top ranked OTUs.
Facilitation in the abstract selection task: The effects of attentional and instructional factors

The present study examined performance on Wason's four-card abstract selection task. Baseline performance is very poor, usually less than 10% correct; and this task has a long record of resistance to facilitation. It was hypothesized that the two primary sources of difficulty are selective encoding of the problem information and the lack of satisfactory analytic processing. Three experiments were conducted to test this hypothesis. In Experiment 1, performance was improved by explicating the implication rule. The majority of subjects, however, still failed to make the correct selection. Subjects were required in Experiment 2 to provide reasons for their selection or non-selection of each of the cards. This response procedure, paired with an explicated rule, led to further improvements in performance (over 50% correct selections). In Experiment 3, the influence of the type of selection instruction (true-false vs. violation) was examined. Paired with an explicated rule and the reasons response format, violat...
Novel resists with nontraditional compositions for EUV lithography

EUV lithography is to date the most promising NGL technology for the sub-50nm technology node. In this work, we have designed and synthesized several types of organoelement resists with low oxygen content for high transparency. Boron was incorporated in the resist structures to improve both etch resistance and transparency. Both negative-tone and positive-tone resists were made containing the carborane group. In a preliminary study, these polymers were imaged using a 248nm stepper to produce images with good resolution. The incorporation of a carborane structure provides these polymers with excellent oxygen etch resistance. Hall effect measurements were performed and no contamination was found in the substrate after applying boron-containing polymers.
Shaken Baby Syndrome

Unfortunately, head trauma caused by shaken baby syndrome is a common occurrence in infants and young children. The proper treatment and safety of these children can be enhanced by the nurse's ability to recognize features characteristic of this syndrome. If abuse is suspected, appropriate physicians, child-protective, and law-enforcement agencies should be notified immediately. Further research must be done to improve the understanding of the mechanisms associated with this disorder in the ultimate hope of improving the lives and outcome of infants and children.
Interactions between enzyme-forming systems during adaptation.

Experiments on enzymatic adaptations in yeast to galactose and maltose under various conditions are examined. The pertinent facts established may be summarized as follows:— 1. The presence of exogenous nitrogen stimulates the rate of adaptation and raises considerably the attainable level of enzyme activity. 2. This stimulation is absent if the cells are unable to assimilate the added nitrogen. 3. Competitive interactions can be exhibited between two adaptive enzyme systems induced either serially or simultaneously in the same cell. 4. A similar kind of interaction was observed between an adaptive and a so called "constitutive" enzyme. 5. The presence of exogenous nitrogen modifies greatly the nature and extent of the interaction between the enzyme-forming systems. The significance of these results to our understanding of the mechanism of the modification and maintenance of cellular enzymatic constitution is discussed. The validity of the distinction between "constitutive" and "adaptive" enzymes is reexamined in the light of the data presented.
Modeling Proteins and Small Molecules with Inhomogeneous Dielectric Function: Implementation in Delphi

Most implicit solvent models treat bio-molecules as homogeneous dielectric medium inside high dielectric water phase. However, the dielectric distribution inside biological macromolecules is non-homogeneous, which depends on various factors, such as amino acid composition, structure, packing and flexibility. Many approaches have been developed to model the inhomogeneous dielectric distribution in biomolecules, including amino acid specific dielectric constant, using non-typical probe radius in finite-difference algorithm or delivering the dielectric constant from Gaussian distribution of atomic densities. Here, in DelPhi program, we developed an inhomogeneous dielectric method based on Gaussian smooth function. We tested this new method on calculating the solvation energies of 504 small molecules and the results show the method achieves better accuracy of the solvation energy calculation than homogeneous dielectric methods. Other tests on real proteins demonstrate that our inhomogeneous dielectric method is more reliable than homogeneous dielectric method for pKa and electrostatic potential calculations.
An analysis of trends in oxidant air quality in the south coast air basin of California

Abstract Previous approaches for meteorological adjustment of oxidant trends were based on establishing a statistical or deterministic model between oxidant concentrations and meteorological parameters. This model was then used to remove the influence of meteorology. However, because of the simplistic forms of the models, they are not capable of removing meteorological effects for all years. To circumvent this problem, the daily peak oxidant trends have been determined based on fixed ranges of meteorological parameters, as well as on fixed parameter values using year-specific statistical models. Trends were determined for regional maxima, and at two specific sites Azusa and San Bernardino, over the high oxidant season from 1971 to 1979. The parameters selected to characterize the oxidant concentrations are the daily values of El Monte upperlevel temperature, maximum Ontario surface temperature, relative humidity, mixing height and wind speed. Fixed ranges or values of these parameters were further classified according to their high, moderate and low oxidant formation potential. Oxidant trends were determined for each classification. Between 1971 and 1979, for days with high oxidant formation potential, the oxidant trends are flat for Azusa, for San Bernardino and basinwide. For days with moderate and low oxidant formation potential, the trends are essentially flat, with minor variations depending on which approach is used to determine the trend.
Fetal and neonatal exposure to the endocrine disruptor, methoxychlor, reduces lean body mass and bone mineral density and increases cortical porosity.

Endogenous estrogen has beneficial effects on mature bone and negatively affects the developing skeleton, whereas the effect of environmental estrogens is not known. Methoxychlor (MXC) is a synthetic estrogen known as a persistent organochlorine and used as a pesticide. Methoxychlor and its metabolites display estrogenic, anti-estrogenic and anti-androgenic activity and may therefore influence bone. Fifty-eight male fetal and neonatal rats were exposed to either: a negative control (DMSO), 0.020, 100 mg/kg MXC, or 1 mg/kg β-estradiol-3-benzoate (EB; positive control). Rats were treated daily for 11 days, from embryonic day 19 to postnatal day (PND) 7 or for 4 days during the postnatal period (PND 0–7). All rats were analyzed at PND-84. Total body, femur, spine, and tibia areal bone mineral density (BMD) and content (BMC), lean body mass (LBM) and fat were measured by dual energy X-ray absorptiometry. Bone geometry and volumetric (v) BMD were measured using micro-computed tomography and biomechanical properties using three-point bending were assessed. Rats exposed to EB or MXC (at either the high and/or low dose), independent of exposure interval showed lower body weight, LBM, tibia and femur BMD and length, and total body BMD and BMC than DMSO control group (p ≤ 0.05). Methoxychlor and EB exposure increased cortical porosity compared to DMSO controls. Trabecular vBMD, number and separation, and cortical polar moment of inertia and cross-sectional area were lower due to EB exposure compared to control (p < 0.05). Early MXC exposure compromises cortical porosity and bone size at maturity, and could ultimately increase the risk of fracture with aging.
A Bias Estimator of the Environmental Resource Base in Diet Preference Studies with Fish

ABSTRACT An assessment of the resource base for determining dietary preference is obtained by using the pooled stomach content data derived from all fish collected at a study site. The assessment provides a different bias than is obtained by using standard independent environmental sampling methods, in that all food taken by the fish community is included in the preference estimates. An important characteristic of a preference index is its conservativeness.
Caenorhabditis elegans metabolic gene regulatory networks govern the cellular economy

Diet greatly impacts metabolism in health and disease. In response to the presence or absence of specific nutrients, metabolic gene regulatory networks sense the metabolic state of the cell and regulate metabolic flux accordingly, for instance by the transcriptional control of metabolic enzymes. Here, we discuss recent insights regarding metazoan metabolic regulatory networks using the nematode Caenorhabditis elegans as a model, including the modular organization of metabolic gene regulatory networks, the prominent impact of diet on the transcriptome and metabolome, specialized roles of nuclear hormone receptors (NHRs) in responding to dietary conditions, regulation of metabolic genes and metabolic regulators by miRNAs, and feedback between metabolic genes and their regulators.
Socioemotional development across cultures: context, complexity, and pathways.

Socioemotional Development Across Cultures needs to be examined with attention to cultural context, cultural complexity, and cultural pathways.
Prospective trial incorporating pre-/mid-treatment [18F]-misonidazole positron emission tomography for head-and-neck cancer patients undergoing concurrent chemoradiotherapy.

Purpose To report the results from a prospective study of a series of locoregionally advanced head-and-neck cancer patients treated with platinum-based chemotherapy and intensity-modulated radiotherapy and to discuss the findings of their pre-/mid-treatment [ 18 F]-misonidazole ( 18 F-FMISO) positron emission tomography (PET) scans. Methods and Materials A total of 28 patients agreed to participate in this study. Of these 28 patients, 20 (90% with an oropharyngeal primary cancer) were able to undergo the requirements of the protocol. Each patient underwent four PET scans: one pretreatment fluorodeoxyglucose PET/computed tomography scan, two pretreatment 18 F-FMISO PET/computed tomography scans, and a third 18 F-FMISO PET (mid-treatment) scan performed 4 weeks after the start of chemoradiotherapy. The 18 F-FMISO PET scans were acquired 2-3 h after tracer administration. Patients were treated with 2-3 cycles of platinum-based chemotherapy concurrent with definitive intensity-modulated radiotherapy. Results A heterogeneous distribution of 18 F-FMISO was noted in the primary and/or nodal disease in 90% of the patients. Two patients had persistent detectable hypoxia on their third mid-treatment 18 F-FMISO PET scan. One patient experienced regional/distant failure but had no detectable residual hypoxia on the mid-treatment 18 F-FMISO PET scan. Conclusion Excellent locoregional control was observed in this series of head-and-neck cancer patients treated with concurrent platinum-based chemotherapy and intensity-modulated radiotherapy despite evidence of detectable hypoxia on the pretreatment 18 F-FMISO PET/computed tomography scans of 18 of 20 patients. In this prospective study, neither the presence nor the absence of hypoxia, as defined by positive 18 F-FMISO findings on the mid-treatment PET scan, correlated with patient outcome. The results of this study have confirmed similar results reported previously.
On Weil-Petersson Volumes and Geometry of Random Hyperbolic Surfaces

This paper investigates the geometric properties of random hyperbolic surfaces with respect to the Weil-Petersson measure. We describe the relationship between the behavior of lengths of simple closed geodesics on a hyperbolic surface and properties of the moduli space of such surfaces. First, we study the asymptotic behavior of Weil-Petersson volumes of the moduli spaces of hyperbolic surfaces of genus g as g ! 1. Then we apply these asymptotic estimates to study the geometric properties of random hyperbolic surfaces, such as the length of the shortest simple closed geodesic of a given combinatorial type.
Anthracene electron-transfer photosensitizers for onium salt induced cationic photopolymerizations

This article describes the synthesis of several derivatives of anthracene (AN) and their evaluation as electron-transfer photosensitizers for onium salt induced cationic photopolymerizations. The synthetic methods that were employed involved straightforward and high yield routes to these derivatives. Using Fourier transform real-time infrared spectroscopy (FT-RTIR), the photoinduced polymerizations of several model epoxide and vinyl ether monomers were examined in the presence and absence of the anthracene photosensitizers. It was observed that anthracene derivatives bearing electron-donating substituents markedly accelerated the rates of all the UV irradiation induced photopolymerizations in which diaryliodonium, triarylsulfonium and dialkylphenacylsulfonium salt photoinitiators were used. In each case, the greatest acceleration of the rate of the polymerizations occurred when 9,10-dialkoxyanthracenes were employed as photosensitizers.
Unusual binding stoichiometries and cooperativity are observed during binary and ternary complex formation in the single active pore of R67 dihydrofolate reductase, a D2 symmetric protein.

R67 dihydrofolate reductase (DHFR) is an R-plasmid-encoded enzyme that confers resistance to the antibacterial drug, trimethoprim. This DHFR variant is not homologous in either sequence or structure to chromosomal DHFRs. A recent crystal structure of the active tetrameric species describes a single active site pore that traverses the length of the protein (Narayana et al., 1995). Related sites (due to a 222 symmetry element at the center of the active site pore) are used for binding of ligands, i.e., each half-pore can accommodate either the substrate, dihydrofolate, or the cofactor, NADPH, although dihydrofolate and NADPH are bound differently. Ligand binding in R67 DHFR was evaluated using time-resolved fluorescence anisotropy and isothermal titration calorimetry techniques. Under binary complex conditions, two molecules of either NADPH, folate, dihydrofolate, or N10 propargyl-5,8-dideazafolate (CB3717) can be bound. Binding of NADPH displays negative cooperativity, binding of either folate or dihydrofolate shows positive cooperativity, and binding of CB3717 shows two identical sites. Any asymmetry introduced by binding of one ligand is proposed to induce the cooperativity associated with binding of the second ligand. Evaluation of ternary complex formation demonstrates that one molecule of folate binds to a 1:1 mixture of R67 DHFR+NADPH. These binding results indicate a maximum of two ligands bind in the pore. A mechanism describing catalysis is proposed that is consistent with the binding results.
On the determination of polymer‐polymer interaction parameter by inverse gas chromatography

Dans l'expression de l'energie libre de Flory-Huggins, on introduit une dependance en composition phenomenologique
Construction of a vein-pouch aneurysm at a surgically created carotid bifurcation in the rat

Currently available animal models for the study of treatment of aneurysms are either expensive or yield unreliable results. An animal series was devised to address both of these problems by creating a new animal model. Twelve Sprague-Dawley rats were used to demonstrate that a vein-pouch aneurysm could be constructed at a surgically created carotid bifurcation. Patency rates, growth dynamics, and histologic morphology were studied at three time intervals. A 100% patency rate at the aneurysm orifice was achieved with one-third of the aneurysms showing varying degrees of partial apical thrombosis. A growth pattern was established over the study period. Magnetic resonance angiography and digital subtraction angiography were successfully employed to study a small number of additional aneurysms. Our conclusion is that a bifurcation aneurysm can be constructed in the rat with high patency rates and predictable saccular morphology which resembles most human intracranial aneurysms. This inexpensive animal model can be used to study novel modalities for the treatment of aneurysms.
Influence of asperities along subduction interfaces on the stressing and seismicity of adjacent areas

Abstract Dmowska, R. and Lovison, L.C., 1992. Influence of asperities along subduction interfaces on the stressing and seismicity of adjacent areas. In: T. Mikumo, K. Aki, M. Ohnaka, L.J. Ruff and P.K.P. Spudich (Editors), Earthquake Source Physics and Earthquake Precursors. Tectonophysics , 211: 23–43. We have investigated the influence of large-scale fault inhomogeneities in large subduction earthquakes on the style of deformation and seismic behavior of the incoming oceanic plate and slab at intermediate depths during the earthquake cycle. The zones of the large subduction events of Rat Islands 1965, Alaska 1964 and Valparaiso 1985 have been searched for earthquakes with m b ⩾ 5.0, if available, and for time periods as long as possible. It has been found that in general the seismicity in the incoming oceanic plate clusters in front of asperities ( areas of highest seismic moment release and strongest locking) and is positioned relative to them in the direction of plate motion. It is usually lacking in areas adjacent to non-asperities, that is to zones that slip during the main event but with appreciably smaller seismic moment release, and possibly slip seismically/aseismically during the whole cycle. Similar behavior occurs in the downgoing slab at intermediate depths, where seismicity during the cycle clusters (but less strongly than in the oceanic crust) next to asperities and down-dip from them. We infer that the locking of asperities causes higher stresses associated with the earthquake cycle itself to occur in areas adjacent to asperities, both up-dip and down-dip from them along the direction of plate motion, and that such stressing is much less pronounced in the areas adjacent to non-asperities. This opens the possibility of identifying the areas of highest seismic moment release in future subduction earthquakes, and carries implications for where the highest deformation and, possibly, precursory phenomena and/or nucleation of a future event might occur.
Procurement under uncertain supply lead times — A dual- sourcing technique could save costs

Abstract Inventory system costs tend to be higher if uncertainty prevails in the supply lead times and consequently in the demand during the lead time because of the possibility of shortages or the need to maintain larger safety stocks. In this paper we explore a dual-sourcing technique in which the replenishment order quantity for the inventoried item with stochastic lead times is split between two sources of supply, and split-orders are placed simultaneously. It is shown that this results in effective lead times with lower variability and hence savings in the inventory holding and shortage costs are possible. If these savings exceed the incremental ordering costs associated with procurement from two sources overall cost economies result. In this paper, the theoretical concepts underlying the dual-sourcing technique and its implications for implementation in procurement management are presented along with an overview of the recent research in the area of dual sourcing.
Behavioral interaction between cocaine and caffeine: A drug discrimination analysis in rats

The effects of caffeine upon the discriminative and rate-altering effects of cocaine were examined in rats. Using a food-reinforced two-lever operant procedure, 12 Sprague-Dawley male rats were trained to discriminate between 10 mg/kg cocaine and saline. Stimulus generalization tests with both cocaine and amphetamine resulted in a dose-related increase in cocaine-appropriate responding. A variable response rate topography was produced by cocaine. Caffeine also engendered a dose-related increase in cocaine-appropriate responding and resulted in a potency ratio of 15:1 when compared to cocaine. In contrast, increasing doses of caffeine produced a biphasic response rate function (first increases and then decreases). Response choice data suggested a potency relationship of amphetamine greater than cocaine greater than caffeine. Caffeine potentiated the discriminative stimulus properties of cocaine. Isobolographic analysis characterized this interaction as simple additivity. However, caffeine's effects upon the rate-altering effects of cocaine resulted in a biphasic interaction pattern. With low doses of cocaine in combination with various doses of caffeine, the interaction for rate reduction is best categorized as "supra-additive," in contrast, increasing either the cocaine dose or caffeine dose could change the interaction to simple additivity and/or infra-additivity.
Complexity and Counterterrorism: Thinking about Biometrics

Biometrics, which relies on physical characteristics to identify individuals, enjoys growing support as a counterterrorist tool. However, there is little evidence in this regard. On the contrary, one danger is that biometric systems, such as national identification cards, would create a new target for terrorists to strike, paralyzing critical infrastructure. Given these limitations, why are countries moving toward this questionable form of security? Advocates of biometrics have been able to make powerful claims that play to public perceptions of risk in general, and the threat of terrorism in particular. This article suggests decentralized methods of identification and verification.
Flow Estimation by Indicator Dilution (Bolus Injection)

Indicator dilution techniques used for the estimation of flow (F), mean transit time (t), dispersion (σ), and mean transit time volume (V) in the circulation are subject to error when (1) flow is not steady and (2) concentrations are obtained by sampling at a constant rate (time averaging) rather than at rates proportional to the instantaneous flow past the sampling site (volume averaging). Using a simple descriptive model for indicator transport, the effects of simulated aortic flow or of sinusoidal flow of widely variable frequency were assessed. Errors in estimates of F, t, σ, and V are greater with bolus injections than with constant-rate injections. Errors are roughly proportional to the amplitude of variation in flow. They are maximal when the period of flow fluctuation is similar to the passage time of the dilution curve, which, for the human central circulation, is about the time for one respiratory cycle. With sinusoidal flow between 50% and 150% of the mean flow, errors were at worst up to 60% i...
Electronic absorption spectroscopy for the investigation of the solution binding of gold, palladium, mercury and silver salts to the lower rim substituted calix[4]arenes 25,26,27,28-(2-N,N-dimethyldithiocarbamoylethoxy)calix[4]arene and 25,26,27,28-(2-methylthioethoxy)calix[4]arene

Abstract The two uncharged compounds 25,26,27,28-(2- N,N -di methyldithiocarbamoylethoxy)calix[4]arene ( 1 ) and 25,26,27,28- (2-methylthioethoxy)calix[4]arene ( 2 ) are effective extractants for transferring Hg(II), Ag(I), Pd(II) and Au(III) from aqueous solution into chloroform. The electronic absorption spectra of 1 and 2 show additional bands at long wavelength upon complexation with AuCl 4 − , PdCl 4 2− and PdBr 4 2− , and analogous bands for Hg 2+ and Ag + with 1 . For 1 these new bands are considered to be either of the charge transfer type or transitions within the C=S moiety. These new bands for the complexes with 2 are assigned to LMCT transitions of the S → M type. These spectral features are used to obtain information about the solution structures of the complexes that are formed between these metal ions and both 1 and 2 .
Synthesis, Structural Characterization, and Electronic Structure of Single-Crystalline CuxV2O5 Nanowires

Single-crystalline copper vanadium oxide nanowires β′-CuxV2O5 (x ∼ 0.60) have been synthesized by the hydrothermal reduction of bulk CuV2O6 using small-molecule aliphatic alcohols as reducing agents. The prepared copper vanadium bronze nanowires are metallic in nature and exhibit aspect ratios as high as 300. The recent discovery of superconductivity and charge disproportionation in bulk β′-CuxV2O5 has led to renewed interest in these one-dimensional metallic systems. Scaling these systems to nanoscale dimensions offers the potential for further tunability of electronic transport and Li-ion intercalation kinetics. A combination of spectroscopic and electrical measurement methods has been used to provide evidence for the metallic nature and the presence of room-temperature charge disproportionation in these nanowires.
Dynamic Admissible States, Negative Absolute Temperature, and the Entropy Maximum Principle

Gibbs ([1], p. 55) began his major memoir on thermostatics by the dictum of Clausius: “The energy of the universe is constant. The entropy of the universe tends to a maximum.” Replacing the “universe” of Clausius by a down-to-earth “isolated material system”, Gibbs saw the basis for what we now call his Entropy Maximum Principle, which he developed “as a foundation for the general theory of thermodynamic equilibrium” ([2], p. 354). Gibbs’s statement of his entropy principle was vague, but he also applied it (to be precise, here I should have said its companion Energy Minimum Principle, which Gibbs “preferred in general to use”) to a variety of systems. A general principle will assume appropriate specific forms in different concrete problems. On the other hand, after seeing how a vaguely worded, general principle has been used in various situations, we should be able to discern that which is in common. Thence it is no accident that van der Waals ([3], § 2) and Coleman & Noll ([4], § 16) should independently give the same formulation of the Entropy Maximum Principle for the same type of “isolated systems”, for what they gave is in essence Gibbs’s original formulation and they expressed it in the language of fields. The present essay is meant to be a critique of this formulation.
Wearable computing: a human-centered view of key concepts, application domains, and quality factors

This tutorial presents a human-centered view of the state-of-the-art of wearable computing. Considering scientific and industrial aspects, it provides key definitions in the domain, goes through practical applications and use case scenarios, and concludes with quality factors and best design practices. An interactive component will aid participants to apply the theoretical concepts presented.
Through the Looking Glass: Kingly Virtues in Safavid and Mughal Historiography

During the reigns of the Safavid Shah ‘Abbās I and the Mughal Emperor Akbar, two chroniclers, one from each dynasty, included in their texts lists of “kingly virtues.” This paper explores the possible historiographical precedents for this section in the chronicles, and places particular emphasis on the “mirrors for princes” literature. The paper concludes with a suggestion that reading the narrative portions of the chronicles in light of the mirrors for princes literature helps us understand why chroniclers may have included certain information in those sections.
Chronic obstructive pulmonary disease: Emergency care in acute exacerbation

Chronic obstructive pulmonary disease (COPD) is a preventable condition affecting more than 230 million people globally, and is expected to become the world's third largest cause of mortality by 2030. Despite this fact, it is thought to be widely underdiagnosed and underreported across the African continent. This presents a challenge to emergency medicine (EM) providers in the region, who are faced with treating large numbers of patients presenting with exacerbation of previously undiagnosed COPD. This is complicated by other factors, including lack of public awareness, high prevalence of other chronic respiratory illnesses, and difficulties in access to healthcare. The purpose of this paper is to outline the current state of research and international guidelines surrounding the management of acute exacerbation of COPD in the emergency centre. Strict adherence to international guidelines for management of acute exacerbation of COPD may be difficult for many African providers given factors affecting diagnosis, treatment, and access to care for many Africans suffering from COPD. Research looking into the role of the African EM practitioner in providing more cost-effective means of diagnosis and treatment of COPD is limited.
Saturn's main ring particle size distribution: An analytic approach

An analytic theory for Saturn's ring particle size distribution is developed using the so-called “dynamic ephemeral bodies” (or DEBs) model of ring particles (S.J. Weidenschilling, C.R. Chapman, D.R. Davis, and R. Greenberg, 1984, in Planetary Rings, pp. 367–416, Univ. of Arizona Press, Tucson). Accretion and erosion criteria are defined, and the fundamental integrodifferential equation describing the collisional evolution of the mass distribution function of ring particles is derived in the approximation that the ring velocity dispersion is independent of the particle size. A simple stationary solution of this equation is developed, which reproduces all the main features of the distributions determined from the Voyager I radio data (H.A. Zebker, E.A. Marouf, and G.L. Tyler, 1985, Icarus 64, 531–568). The main results of this work are the following: (i) the upper cutoff of the distribution can be explained by a relative enhancement of the erosion of the large particles; (ii) the power-law index of the distribution can be related to parameters characterizing the particle collisional properties; (iii) the model yields estimates for the particle life times and for the dispersion velocity in various unperturbed regions of the rings; (iv) “hard-sphere” ring particle models are most probably ruled out, because they lead to stationary distribution functions in disagreement with the Voyager results.
Aikido: A Model for Brief Strategic Therapy

Building on Watzlawick's observations of certain similarities between judo and brief strategic therapy, this paper develops theoretic and pragmatic parallels between brief strategic therapy and a sophisticated martial art system, Aikido. After presenting the contextual similarities of the two conceptual systems as parallel “challenges” to the therapist and Aikidoist to effect change, the similarities in basic principles of practice are presented. The similarities in the philosophical and attitudinal positions of these conceptual systems are then delineated, followed by a case example that integrates the various concepts in the paper.