cssi/SciSciGPT-SciSciNet huggingface dataset:
Nonlinear theory of electron neutralization waves in ion beams with dissipation

An analytical theory of nonlinear neutralization waves generated by injection of electrons from a grid in the direction of a homogeneous ion beam of uniform velocity and infinite extension is presented. The electrons are assumed to interact with the ions through the self‐consistent space charge field and by strong collective interactions, while diffusion in the pressure gradient is disregarded (zero‐temperature approximation). The associated nonlinear boundary‐value problem is solved in closed form by means of a von Mises transformation. It is shown that the electron gas moves into the ion space in the form of a discontinuous neutralization wave, which exhibits a periodic field structure (incomplete neutralization). This periodic wave structure is damped out by intercomponent momentum transfer, i.e., after a few relaxation lengths a quasineutral plasma results. The relaxation scale in space agrees with neutralization experiments of rarefied ion beams if the collective momentum transfer between the electron and ion streams is assumed to be of the Buneman type.
Fine‐structure mapping of genes providing susceptibility to asthma on chromosome 5q31–q33

Summary In summary, the fine-structure mapping of chromosome 5q31–q33 for genes providing susceptibility to asthma will involve multiple steps. High resolution linkage analyses, will better define the‘critical’ region harbouring a gene(s) determining risk factors such as BHR and elevated serum IgE in asthma. The chromosomal region specified will be subcloned (YACs) and assembled into overlapping fragments providing a physical map that includes the relative positions of markers and candidate genes. Gene candidates will be scrutinized for genetic mutations on the basis of their chromosomal location and the likelihood of their involvement in the pulmonary inflammatory response central to the patho-physiology of asthma. If none of the known candidate genes mapped to the critical region of chromosome 5q are shown to cause asthma, new genes expressed within cells in lung and potentially important in asthma will be identified by direct selection and exon trapping. These reagents and studies will facilitate the process of gene discovery in allergy and asthma, and lead to new diagnostic, preventive, and therapeutic approaches to this common disorder.
Importance of tuber eye posiion when indexing for the leafroll virus

Eyes were removed from the stem ends, middle position, and bud ends of leafroll-infected Kennebec, Norland, Red Pontiac, F91-2, and seedling potato tubers to determine which position is the most reliable for expressing leafroll symptoms in greenhouse plants grown from them. The bud end was found to be the most satisfactory.
Ablation Rate Estimates over the Greenland Ice Sheet from Microwave Radiometric Data

Scanning Multichannel Microwave Radiometer (SMMR) data are used to estimate the annual melt duration (number of days with melt) for elevation transects over the Greenland ice sheet during the period from 1979-1986. The annual melt duration is used to estimate the number of positive degree days (PDDs), which are used in a degree-day mass balance model to determine ablation rates and the equilibrium line altitude (ELA). The annual melt duration along two transects estimated with SMMR data compares favorably, particularly above the ELA, to melt duration calculated from surface temperature data for the same locations. The mass balance estimates and ELA locations along eight transects agree reasonably well with measurements reported in previous studies using surface temperature data. ELAs were within 10m of published values along two transects, and the root mean square error of SMMR-derived versus surface mass balance measurements was 43mm yr−1. The estimated error in SMMR-derived ablation is between ±15% and ...
Practical Clinical Pharmacology and Drug Interactions of Low-Dose Methotrexate Therapy in Rheumatoid Arthritis

The clinical pharmacology and clinically important drug interactions of methotrexate (MTX) are reviewed. The points discussed are as follows. (a) The bioavailability of oral preparations of MTX is approximately 15-20% lower than that of intramuscular or intravenous MTX, although there is great variability in relative bioavailability. (b) Protein-binding displacements are unlikely to be of importance with this low-to-medium protein-binding drug. Because MTX is polyglutamated and remains within cells, dialysis is unlikely to be an effective mode of elimination. The principal excretory pathway of MTX is via the kidneys, although some is also excreted through the bile. These facts imply that: (i) MTX needs to be used with extreme caution, if at all, in the face of renal insufficiency; (ii) cholestyramine may be used to enhance the biliary excretion of MTX; and (iii) probenecid may be a cost-effective way to increase the efficacy of MTX. (c) Although aspirin inhibits MTX clearance more than other non-steroidal anti-inflammatory drugs (NSAIDs), clinical toxicity of aspirin is not significantly greater than that of other NSAIDs. In all cases this negative interaction is very rare (although, of course, it needs to be considered at all times). (d) It is possible that corticosteroids inhibit MTX metabolism, although this requires significant research. (e) Trimethoprim-sulphamethoxazole (TS) toxicity is well documented and may be related to synergistic anti-folate effects of MTX and TS. (f) Folic acid decreases MTX toxicity, possibly through an effect on dihydrofolate reductase.
CONSIDERATIONS IN CALCULATING KINETIC PARAMETERS FROM EXPERIMENTAL DATA

Engineers require quantitative models to design and optimize processes. In the food industry, these process models become very complex because of the unique physical/chemical characteristics and variability of the raw material. Furthermore, frequently data describing rates of reactions and/or changes in foods are generated by food scientists who are not thoroughly familiar with reaction models. Analysis of those data to obtain parameters for reaction models thus becomes critical. In this paper, calculating kinetic parameters from experimental data is examined, and suggestions are presented for determining reaction rates and temperature dependence.
Global SunFarm data acquisition network, energy CRADLE, and time series analysis

Outdoor testing of photovoltaic (PV) modules plays a critical role in discovering the degradation modes, mechanisms and rates of materials, components and systems under real world climate conditions. The Solar Durability and Lifetime Extension (SDLE) center at Case Western Reserve University has established a highly instrumented outdoor test facility, the SDLE SunFarm. In order to study PV module performance under different climatic conditions, a global SunFarm network was established with nine PV outdoor test beds across the world. Energy CRADLE is an ontology driven database acquisition tool which is being developed to effectively store, analyze and query huge data sets generated by the SunFarms. The data collected from all these data sources will stream back to a MySQL database. A front end user interface was built for the purpose of data inquiry, equipment registration, maintenance, and metrology cross check. Design and characteristics of SunFarms are introduced. SunFarm informatics and two case studies will be discussed in this article.
Determination of organoarsenicals in the environment by solid-phase microextraction-gas chromatography-mass spectrometry.

The development of a method for the analysis of organoarsenic compounds that combines dithiol derivatization with solid-phase microextraction (SPME) sample preparation and gas chromatography-mass spectrometry (GC-MS) is described. Optimization focused on a SPME-GC-MS procedure for determination of 2-chlorovinylarsonous acid (CVAA), the primary decomposition product of the chemical warfare agent known as Lewisite. Two other organoarsenic compounds of environmental interest, dimethylarsinic acid and phenylarsonic acid, were also studied. A series of dithiol compounds was examined for derivatization of the arsenicals, and the best results were obtained either with 1,3-propanedithiol or 1,2-ethanedithiol. The derivatization procedure, fiber type, and extraction time were optimized. For CVAA, calibration curves were linear over three orders of magnitude and limits-of-detection were < 6.10(-9) M in solution, the latter a more than 400 x improvement compared to conventional solvent extraction GC-MS methods. A precision of < 10% R.S.D. was typical for the SPME-GC-MS procedure. The method was applied to a series of water samples and soil/sediment extracts, as well as to aged soil samples that had been contaminated with Lewisite.
Abstract 5331: The effect of heat shock protein 27 (HSP27) on prostate cancer cell adhesion, invasion and metastasis

Proceedings: AACR 103rd Annual Meeting 2012‐‐ Mar 31‐Apr 4, 2012; Chicago, IL Prostate cancer (PCa) is the most commonly diagnosed form of cancer among American men, and the second leading cause of all cancer-related deaths. PCa death is caused by the process of metastasis. In order to metastasize, tumor cells must acquire a series of phenotypic alterations, collectively known as the metastatic cascade. We have demonstrated that the small heat-shock protein, HSP27, affects key early steps of the metastatic cascade, and therefore may be a regulator of human PCa metastasis. HSP27 protein expression increases during PCa progression. It is phosphorylated in response to signaling from transforming growth factor-β (TGF-β), which in turn increases matrix metalloproteinase 2 (MMP-2) and cell invasion in vitro. We now demonstrate that HSP27 does not affect human PCa cell adhesion, cell detachment or cell migration, all of which contribute to the composite function of cell invasion. We went on to show that proteolysis by MMPs is necessary for HSP27-driven cell invasion by demonstrating that it was abrogated Marimastat, a broad-spectrum MMP inhibitor. By orthotopically implanting HSP27 variant human PCa cell lines, we demonstrated that HSP27 increases metastasis in a murine model. We also found that HSP27 increased tumor size. HSP27 increases human PCa metastasis and tumor growth in vivo. These findings provide a mechanistic explanation for the poor prognosis associated with increased HSP27 expression in human prostate tissue. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5331. doi:1538-7445.AM2012-5331
First Principles Molecular Dynamics Studies of Liquid and Solid Sodium

One of the outstanding problems in materials science is the lack of a fundamental theory of melting and freezing. Such a theory would be extremely useful in the search for new materials. For example, the high-temperature properties of alloys almost always limit the efficiency that can be achieved in an engine or power plant. Also the mechanical strength of materials is often determined by the distribution of impurities, which in turn is a result of the cooling or annealing that occurs during pro cessing. To address these problems we have used the technique of molecular dynamics simulation in which 50 to 100 atoms are followed on the computer as they move. From these simulations it is possible to calculate the important thermal properties such as the rate of dif fusion, the internal energy, the free energy, and the volume of the material above and below the melting temperature. These calculations make use of a new theory that combines molecular dynamics simulation with calculations of the electron states and therefore re quires no adjustable parameters as inputs.
Discharge of intrapulmonary chemoreceptors and its modulation by rapid F1CO2 changes in decerebrate ducks.

Abstract Single-unit activity was recorded from intrapulmonary chemoreceptors (IPC) in decerebrate ducks inspiring room air (fresh air or control breath), or a short pulse of room air preceded and followed by 5% CO2 (fresh air pulse or experimental breath). Of 36 IPC studied, 28 fired a burst of impulses of similar duration to the fresh air pulse; delaying the fresh air pulse until later and later in inspiration progressively delayed the IPC burst. The remaining 8 IPC did not respond discretely to the fresh air pulse, rather their discharge was reduced diffusely in one or both of the ventilatory phases. The average discharge of the IPC population had a cyclic character during control breathing, with peak discharge mid-way through inspiration and essentially a constant discharge during expiration. An experimental breath had a similar IPC discharge pattern but peak inspiratory discharge was reduced; delaying the fresh air pulse delayed the population IPC burst. The results indicate that IPC could mediate the previously reported changes in T i and T e that occur when the timing of a fresh air pulse is manipulated in conscious chickens [(Tallman et al. (1979). Am. J. Physiol. 237: R260–R265)].
Defining units in the quantum based SI

Possible changes to the International System of Units (SI) are being discussed, including a proposal to define the units by specifying the values of a set of fundamental constants. This note is an elementary guide to the algebra associated with unit exponents which can be used both to display the relationships between different sets of units and to provide simple tests of whether a particular set of constants provides combinations of units that form a complete set.
Six Innexins Contribute to Electrical Coupling of C. elegans Body-Wall Muscle

C. elegans body-wall muscle cells are electrically coupled through gap junctions. Previous studies suggest that UNC-9 is an important, but not the only, innexin mediating the electrical coupling. Here we analyzed junctional current (Ij) for mutants of additional innexins to identify the remaining innexin(s) important to the coupling. The results suggest that a total of six innexins contribute to the coupling, including UNC-9, INX-1, INX-10, INX-11, INX-16, and INX-18. The Ij deficiency in each mutant was rescued completely by expressing the corresponding wild-type innexin specifically in muscle, suggesting that the innexins function cell-autonomously. Comparisons of Ij between various single, double, and triple mutants suggest that the six innexins probably form two distinct populations of gap junctions with one population consisting of UNC-9 and INX-18 and the other consisting of the remaining four innexins. Consistent with their roles in muscle electrical coupling, five of the six innexins showed punctate localization at muscle intercellular junctions when expressed as GFP- or epitope-tagged proteins, and muscle expression was detected for four of them when assessed by expressing GFP under the control of innexin promoters. The results may serve as a solid foundation for further explorations of structural and functional properties of gap junctions in C. elegans body-wall muscle.
Partitioning multi-edge graphs

We introduce a new kind of graph called “multi-edge graph” which arises in many applications such as finite state Markov chains and broadcasting communication networks. A cluster in such a graph is a set of nodes such that for any ordered pair of nodes, there is a path of multi-edges from one to the other such that these edges remain within the same set. We give two algorithms to partition a multi-edge graph into maximal clusters. Both these algorithms are based on the depth-first search algorithm to find strongly connected components of the directed graph. We also discuss some applications of clustering in multi-edge graphs.
Dynamic stability investigations — On the selection of governor parameters

Abstract The selection of values of the governor parameters in dynamic stability studies has acquired importance. A procedure has been suggested by which upper limits of the values of governor parameters can be specified.
A Methodology for Design Ontology Modeling

Recent research has focused on the use of ontologies to promote the sharing of knowledge. Ontologies are becoming increasingly important because they provide the critical semantic foundation for the rapidly expanding field of knowledge. They are very useful for knowledge reuse, knowledge sharing, and enterprise modeling. A design ontology is a hierarchically structured set of terms for describing a design domain that can be used as a skeletal foundation for a knowledge base. It can help the collaborative design team by providing accurate design information and guidelines. This research develops a methodology called domain knowledge acquisition process (DKAP) for creating an ontology of product and process design using IDEF5 and generates a consistency matrix for checking the accuracy of captured information. DKAP is a step-by-step methodology, which captures the product & process design knowledge, stores this knowledge in a reusable format, and shares this knowledge across enterprises. DKAP addresses three critical aspects of a design ontology. It explores the availability of similar domain ontologies for reuse, checks the accuracy & consistency of captured knowledge, and allows the sharing of the captured knowledge.
Comparison of the myelin period of peripheral and central origin by electron microscopy.

The repeating radial periods of some peripheral and central nervous system myelin sheaths in albino rats were compared in an electron microscopic study. Essentially the peripheral myelin period appeared to be larger than the central by about 10%. This result confirmed earlier wide-angle X-ray diffraction data. Direction of sectioning was observed to affect the myelin period, probably proportionally to the hardness of the embedded tissue blocks. Microscopical procedures also tended to increase the spreading of the measurements provided the myelin period was assumed to be similar within the same part of the nervous system in the same animal species. This was elucidated by comparing differences obtained in the same and separate microscopy sessions. Possible causes of error were discussed.
Innovation, diffusion, and culture contact: The holocene archaeology of Ghana

Stressing recent research, this review of Ghana archaeology highlights what we know of the advent of sedentism, agriculture, iron technology, and urbanism in Ghana and examines how certain patterns in Ghanaian prehistory depart from the expectations of the progressive evolutionary model that has framed our understanding of world prehistory. It is also argued that the archaeology of Ghana has much to contribute to current debates on the relationship between material culture and identity, and the impact of the Atlantic economy on non-European peoples, and to our understanding of cultural diversity in the past.
Integrated Optical Resonators: Progress in 2011

We present a review of the research on integrated optical resonators published in 2011. In particular, we focus on microdisk and microring devices and discuss high-quality factor resonators, methods to tune and trim the resonance wavelength, as well as device applications in optical communications, frequency comb generation, all-optical signal processing, sensing, and single-mode lasers.
Evaluating the Potential for Halogen Bonding in the Oxyanion Hole of Ketosteroid Isomerase Using Unnatural Amino Acid Mutagenesis

There has recently been an increasing interest in controlling macromolecular conformations and interactions through halogen bonding. Halogen bonds are favorable electrostatic interactions between polarized, electropositive chlorine, bromine, or iodine atoms and electronegative atoms such as oxygen or nitrogen. These interactions have been likened to hydrogen bonds in terms of their favored acceptor molecules, their geometries, and their energetics. We asked whether a halogen bond could replace a hydrogen bond in the oxyanion hole of ketosteroid isomerase, using semisynthetic enzymes containing para-halogenated phenylalanine derivatives to replace the tyrosine hydrogen bond donor. Formation of a halogen bond to the oxyanion in the transition state would be expected to rescue the effects of mutation to phenylalanine, but all of the halogenated enzymes were comparable in activity to the phenylalanine mutant. We conclude that, at least in this active site, a halogen bond cannot functionally replace a hydrogen...
Radiation quality of californium-252.

The radiation quality of 252Cf has been determined in a tissue-equivalent phantom for simulated sample sizes of 1 and 2 μm. The measurements were made with a 2.54 cm spherical proportional counter of tissue-equivalent plastic with a source-to-counter distance of 7.8 cm. Event spectra have been obtained for lineal energy densities between 0.04 and 103 keV μm-1. The distributions in both lineal energy density and LET are presented. The dose mean of the distribution in lineal energy density is 38 keV μm-1 for the 1 μm site and 34 keV μm-1 for the 2 μm site. Correspondingly, the dose mean values of the distribution in LET are 34 and 30 keV μm-1 respectively. A mean quality factor of about six for 252Cf is obtained for the geometry used here. The absorbed dose rate per unit source mass was found to be 11 rad s-1 g-1, in substantial agreement with most previous measurements, and the ratio of absorbed dose due to protons and other heavy particles to that of electrons is approximately 0.9.
Effects of Multiple Scattering on Ultrasonic Velocity, Attenuation and Backscattering Noise in Polycrystals

Understanding the propagation of ultrasonic waves in polycrystals is important in nondestructive evaluation, both for the purpose of properly detecting or interpreting signals scattered from discrete flaws and for characterizing the microstructure itself. In this paper, the use of the unified theory for elastic wave propagation, developed by Stanke and Kino and based on the second order Keller approximation, is first discussed. After a brief review of the general formalism, recent extensions to the case of polycrystals with preferred grain orientation and elongation are presented. Particular attention is placed on a case commonly found in stainless steels in which the [001] crystallographic axes are aligned and the grains are elongated in the same direction. Techniques to predict the backscattered noise, based on single scattering approximation are then discussed and data motivating the need for extension to include multiple scattering is described. Finally, ways in which these theories can be used to provide improved characterizations of microstructures is indicated.
Relief of tension pneumocephalus with endotracheal intubation.

Abstract Background Pneumocephalus is commonly seen after neurosurgical procedures and is usually of little consequence. When an anatomical 1-way valve develops, there can be significant air entrapment, known as tension pneumocephalus. In cases of craniofacial resection, an iatrogenic ball-valve mechanism involving the nasopharynx can be created. Case Description In this case of craniofacial resection, we find that a tension pneumocephalus developed after surgery, resulting in a change in the patient's mental status. A latissimus dorsi muscle flap, which had been created during surgery, was found to pulsate with the patient's respirations. This flap, along with the patient's nasopharynx, created a ball valve mechanism which led to entrapment and accumulation of intracranial air. This case demonstrates the use of endotracheal intubation as a means of bypassing a 1-way valve of this nature. Conclusion Endotracheal intubation in conjunction with twist drill hole aspiration effectively resolves the pneumocephalus by both providing an outlet for trapped air and by removing the ball-valve mechanism from the circuit. Endotracheal intubation should be considered along with twist drill hole aspiration in the emergent management of tension pneumocephalus secondary to a nasopharyngeal ball-valve mechanism.
Photoisomerization of cis,cis-1,4-Diphenyl-1,3-butadiene in the Solid State: The Bicycle-Pedal Mechanism

The cis−trans photoisomerization of crystalline or powdered cis,cis-1,4-diphenyl-1,3-butadiene (cc-DPB) was studied at room temperature. The progress of the reaction was monitored by fluorescence spectroscopy, powder X-ray diffraction, 1H NMR and HPLC. High conversions (up to 90%) to the trans,trans isomer were observed in a crystal to crystal reaction. Formation of the cis,trans isomer, the sole product obtained in solution and in very viscous glassy media at 77 K is entirely suppressed in the solid state. The observed two-bond photoisomerization is explained by Warshel's bicycle-pedal photoisomerization mechanism (BP). The results are consistent with X-ray diffraction measurements, which have revealed that cc-DPB molecules exist in crystals in edge to face alternating arrays of two conformer structures whose phenyl rings deviate significantly from the plane of the central diene moiety (∼40°).1 One of the conformers has the two phenyls in parallel planes and the other in roughly perpendicular planes. Lea...
Impaired spatial memory in APP-overexpressing mice on a homocysteinemia-inducing diet.

Abstract Consumption of a diet that significantly elevates homocysteine (homocysteinemia) induces cell death in the CA3 hippocampal subfield in amyloid precursor protein (APP) over-expressing transgenic mice but not in wild-type controls. We assessed behavioral and other neuropathological effects of a homocysteinemia-inducing diet in aged APP-overexpressing mice. Starting at 16–18 months of age, mice were fed either a treatment diet lacking folate, choline, and methionine, and supplemented with homocysteine, or a control diet containing normal amounts of folate, choline and methionine but no homocysteine. After 5 months on the experimental diets, performance on a delayed non-matching-to-position working-memory task was unimpaired. In contrast, spatial reference memory in the water maze was impaired in transgenic mice on the treatment diet. Transgenic mice had higher homocysteine levels than wild-type mice even when fed the control diet, suggesting an effect of genotype on homocysteine metabolism. Methyl-donor deficiency did not alter amyloid deposition in the transgenic mice. These results suggest that disrupted homocysteine metabolism may induce Aβ-associated memory impairments and neurodegeneration in APP overexpressing mice.
Human Gene Targeting Favors Insertions Over Deletions

Gene targeting is a powerful technique for manipulating the human genome, but few studies have directly compared the targeting frequencies of various types of vector constructs. Here we show that similar targeting constructs are able to insert nucleotides at the homologous chromosomal target locus more efficiently than they can delete nucleotides, and combination insertion/deletion vectors appear to target at intermediate frequencies. This holds true for deletions ranging from 1 to 334 bp and insertions ranging from 1 to 1332 bp. In addition, vectors designed to inactivate the human hypoxanthine phosphoribosyltransferase gene (HPRT) by deleting nucleotides often produced rearrangements at the target locus that in many cases were due to insertions of multimerized vector constructs, effectively converting a deletion vector into an insertion vector. These findings were obtained when adeno-associated virus vectors were used to efficiently deliver single-stranded DNA targeting constructs, but the same phenomenon was also observed when transfecting linearized double-stranded plasmids. Thus human cells distinguish between deletion and insertion vectors and process their recombination intermediates differently, presumably at the heteroduplex stage, with implications for the design of gene-targeting vectors and the evolution of human genomes.
Effect of the depth and width of the urethral plate on tubularized incised plate urethroplasty

Purpose: We determined the effect of the depth and width of the urethral groove on tubularized incised plate urethroplasty for distal hypospadias.Materials and Methods: We retrospectively reviewed the records of 48 patients who underwent tubularized incised plate urethroplasty for distal hypospadias between September 1996 and December 1998 for whom preoperative evaluation of the depth and width of the urethral groove was available. Patients were examined by an independent clinician a median of 28 months after surgery when the neourethra was calibrated and urinary stream assessed.Results: Of the 48 patients 46 were available for clinical examination. The urinary stream was straight in 40 boys and angled in 8, while none sprayed. Urethral fistula developed in 6 patients with a urethral plate of less than 8 mm. wide (p = 0.001). The urethral groove was deep in 13 cases, moderate in 20 and shallow in 15. There were no differences among these 3 groups in regard to urinary stream direction or fistula rate. Of t...
Cytogenetics in the Practice of Pediatrics

The best known chromosomal abnormalities are alterations in the number of chromosomes. This type of chromosomal alteration is found in approximately 5% of all fetuses, most of whom are unable to survive pregnancy. Because of this selection process, only 0.6% of living newborns have a chromosomal abnormality. Approximately half of this group is grossly clinically abnormal. The remainder may not exhibit any clinical disturbance until later in childhood or at the time of reproduction. The pediatrician must have sufficient knowledge of the overt cytogenetic syndromes to suspect the probable diagnosis. The pediatrician must also be sufficiently informed of the origins of chromosomal abnormalities to participate in the genetic counseling of the parents. Further, many of the recently recognized cytogenetic abnormalities are subtle and difficult to detect. Their demonstration will only be possible if the pediatrician is alert to the clinical situations in which they are likely to occur. HUMAN CHROMOSOMES The chromosomes which are seen through the microscope are chromosomes that have replicated. They are bipartite bodies, each half (or sister chromatid) is identical with the other half (Fig 1). The process of preparing the chromosomes for examination involves arresting cell division so that the chromosome does not undergo the normal process of division. The two chromatids touch each other at the constricted region known as the centromere.
An analysis and computer simulation of using elastic strain energy to promote superconductivity

Both a model and a computer simulation are developed for superconducting electrons to move by releasing strain energy over mesoscopic distances. Rotation of a grain provides unique strain energy patterns to facilitate conduction. Numerical estimates are derived for the size of the force an electron could exert on the end of a grain to cause it to rotate. The numerical estimates take into account both electric fields and a quantum mechanical rate of change of momentum of the electrons. The force necessary to produce a torque to oscillate a grain at the same frequency of an electron wave packet is found to be in the same range. It is also shown that the magnetic field associated with a normal conducting current can disappear when a superconducting electron moves in the direction of a gradient in strain energy. A computer simulation in C++ shows that strain energy patterns from granular rotation can allow a high degree of electron movement through the center of a grain that has an aspect ratio from 8/7 to 2 and from 10 to 20. The range of tilt angle of the grain that allows electron movement is narrower and lower for higher aspect ratios.
Synthesis, characterization, and solvolysis of mono- and bis-S-(glutathionyl) adducts of methylene-bis-(phenylisocyanate) (MDI).

Bifunctional isocyanates are highly reactive compounds that undergo nucleophilic attack by a variety of functional groups available in the biological system. While the etiology of the respiratory disease caused by diisocyanates is not fully understood, a great deal of research has been performed to elucidate the chemical mechanisms involved in the direct and indirect effects of these compounds. Since adducts of isocyanates are found not only to proteins along the entire respiratory tree but also to proteins in the circulatory system, it is likely that a transport mechanism for the isocyanate from the respiratory to the circulatory system exists. The initial reaction of isocyanates with cellular thiols to form thiocarbamates, which are known to release the isocyanate under physiological conditions, is believed to provide a possible carrier mechanism for the isocyanate functional group. Previous work with aliphatic mono-isocyanates and the aromatic diisocyanate toluene diisocyanate has demonstrated the feas...
Calcium/Calmodulin‐Dependent Kinase II Phosphorylates Drosophila Visual Arrestin

Light activation of rhodopsin in the Drosophila photoreceptor induces a G protein-coupled signaling cascade that results in the influx of Ca 2+ into the photoreceptor cells. Immediately following light activation, phosphorylation of a photoreceptor-specific protein, phosrestin I, is detected. Strong sequence similarity to mammalian arrestin and electroretinograms of phosrestin mutants suggest that phosrestin I is involved in light inactivation. We are interested in identifying the protein kinase responsible for the phosphorylation of phosrestin I to link the transmembrane signaling to the light-adaptive response. Type II Ca 2+ /calmodulin-dependent kinase is one of the major classes of protein kinases that regulate cellular responses to transmembrane signals. We show here that partially purified phosrestin I kinase activity can be immunodepleted and immunodetected with antibodies to Ca 2+ /calmodulin-dependent kinase II and that the kinase activity exhibits regulatory properties that are unique to Ca 2+ /calmodulin-dependent kinase II such as Ca 2+ independence after autophosphorylation and inhibition by synthetic peptides containing the Ca 2+ /calmodulin-dependent kinase II autoinhibitory domain. We also show that Ca 2+ /calmodulin-dependent kinase KII activity is present in Drosophila eye preparations. These results are consistent with our hypothesis that Ca 2+ /calmodulin-dependent kinase II phosphorylates phosrestin I. We suggest that Ca 2+ /calmodulin-dependent kinase II plays a regulatory role in Drosophila photoreceptor light adaptation.
Relationship of tobacco mosaic virus (TMV) lesion number and concentration to the rate of lesion production on pinto bean.

IN experiments which required the daily counting of TMV lesions on pinto bean leaves (Phaseolus vulgaris L.) for the purpose of determining specific rates of lesion-appearance, it was noted that those leaves which had the greatest final number of lesions produced a greater percentage of their lesions earlier. Since comparisons of rates of lesion development could be seriously affected by differences arising from this, an attempt was made to determine its cause and extent.
Acarinaria in associations of apid bees (Hymenoptera) and chaetodactylid mites (Acari)

Acarinaria are specialised structures on the bodies of insects that harbour dispersing mites, providing a secure attachment place for the mites. The structures are best known among bees and wasps. Their presence remains enigmatic, however, since the associated mites often have negative or neutral effects on their hosts. A new hypothesis explaining the origin of the acarinarium as a specialised defence mechanism is proposed. In nests with partitions (as constructed by many bees and wasps), parasitic or cleptoparasitic mites are rarely found in all cells. They negatively interact only with host larvae developing in infested cells and apparently cannot disperse within the nest to attack others in the developing brood before bee emergence. Only when emerging bees break the partitions can the mites reach other hosts. We propose that acarinaria serve to concentrate unwanted mites, reducing the chance that they will disperse to other members of the brood as the infested host leaves the nest. Development of special mite pouches (acarinaria) by hymenopteran hosts presumably increases the likelihood that all mites will stay with the individual(s) with reduced fitness, thereby reducing their effect on other bees in the brood. This paper reviews the associations between chaetodactylid mites and long-tongued bees (Apidae and Megachilidae). Only apid bees (Apidae) have acarinaria; megachilid bees, which harbour species of Chaetodactylus that usually kill the bee larvae, do not possess acarinaria. The following associations involving previously undescribed acarinaria or mite species are reported: Achaetodactylus ceratinae (axillar acarinarium on Ceratina nigriceps); Roubikia latebrosa, sp. nov. (metasomal acarinarium on Tetrapedia sp.), Sennertia argentina (genital acarinarium on Xylocopa fimbriata), Sennertia devincta, sp. nov., Sennertia sayutara, sp. nov. (metasomal acarinaria on Ceratina (Zadontomerus) spp.), Sennertia lauta, sp. nov. and Sennertia ratiocinator, sp. nov. (incipient scutellar–metanotal acarinarium on Xylocopa (Zonohirsuta) spp.). In the latter case, the mites display a remarkable difference in the attachment sites between male and female hosts. In females, the mites are phoretic in a groove between the scutellum and metanotum (scutellar–metanotal acarinarium), whereas on males, mites attach to the hairs of the anterior scutum.
Open framework metal monocarboxylates: nickel cyclopropionates containing 16- and 18-membered rings

We have obtained two layered nickel cyclopropanecarboxylates by using hydrothermal synthesis: Ni 9 (OH) 2 (H 2 O) 6 (C 4 H 5 O 2 ) 8 ·2H 2 O ( 1 ) and Ni 5 (OH) 2 (C 4 H 5 O 2 ) 8 ( 2 ). The structures for both materials were solved using single-crystal XRD (( 1 ) Pbcn , a =14.810(3) A, b =24.246(5), c =24.607(5) A, V =8836(3) A 3 , R 1 =0.0575; ( 2 ) Pbca , a =19.406(4) A, b =18.466(4) A, c =21.579(4) A, V =7733(3) A 3 , R 1 =0.0593). Both structures consist of layers based on 2D Ni–O–Ni networks of NiO 6 octahedra decorated by cyclopropanecarboxylate. The layers in ( 1 ) are based on a network of corner- and edge-sharing NiO 6 octahedra forming sheets of 18-member rings, and those in ( 2 ) are based on corner-, edge- and face-sharing NiO 6 octahedra forming 16-membered rings. The synthesis of these materials further illustrates that open-framework hybrid materials with extended metal–oxygen–metal connectivity may be synthesized with monofunctional carboxylates.
Polymorphism of dihydrofolate reductase from a methotrexate-resistant subline of L1210 cells.

Abstract Dihydrofolate reductase, purified to homogeneity (as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis), from a subline of L1210 murine leukemia cells resistant to 10 −6 m methotrexate, was resolved into two principal forms ( 1 and 2 ) by polyacrylamide gel electrophoresis at pH 8.3 or isoelectric focusing. In the latter procedure, these forms had pI values of 7.4 and 8.2, respectively; both stained for protein and catalytic activity. Form 1 appears to be a single component, comprising ca. 10% of the total protein and at least 20% of the total catalytic activity. It is also more sensitive to inhibition by MTX, more heat-stable, and less susceptible to activation than form 2 . Multiple components of 2 were observed by narrowing the pH range in isoelectric focusing, and further resolution was achieved by urea denaturation. Substrate and inhibitor complexes of 1 and 2 , differentiated by polyacrylamide gel electrophoresis or isoelectric focusing, provided information about the ability of the enzyme to undergo conformational changes. Interconversion of 1 with one of the components of 2 may also involve conformational isomerism. These conclusions are consistent with the well-known ability of eukaryotic dihydrofolate reductases to exhibit increased catalytic activity (attributed to transformations to more open conformations) when treated with salts, chaotropes, or cysteine-modifying agents. Treatment of the L1210/R6 enzyme preparation with one of these activating agents, 5,5′-dithiobis(2-nitrobenzoic acid), derivatized both 1 and 2 (changing their pI values to 7.3 and 6.9, respectively) and altered the enzyme such that stoichiometric inhibition for MTX was observed.
Segmental resection of secretory carcinoma of the breast in a young woman: 14-year follow-up

Abstract A 21-year-old woman with a 5-cm secretory carcinoma of the breast was successfully treated by wide segmental excision, including removal of a portion of the nipple. At presentation, she had a 5-year history of predominantly yellow and occasionally bloody discharge from the nipple. The tumour had classical histological features of secretory carcinoma with surrounding hyaline fibrous tissue predominating, a feature previously associated with a good prognosis. Identification by frozen section of extension near the nipple led to intraoperative excision of a nipple segment. She is healthy with a satisfactory cosmetic result 14 years after excision and has breast fed two children from the affected breast.
Antiferromagnetic resonance in tetramethyltetrathiafulvalene bromide [(TMTTF) Br 2 ]

Observation of antiferromagnetic resonance in tetramethyltetrathiafulvalene bromide [(TMTTF)$_{2}\mathrm{Br}$] shows that the semiconducting ground state is antiferromagnetic, with a N\'eel temperature of 13\ifmmode\pm\else\textpm\fi{}1 K. Two modes are observed as a function of magnetic field, for orientations near the easy (${b}^{\ensuremath{'}}$) axis, at a fixed frequency of 9.3 GHz. At 4.2 K the zero-field modes are estimated to have frequencies of 11.7 and 18.2 GHz (4.3 and 6.6 kOe).
Dissolution kinetics: Catalysis by strong acids

The dissolution of silicate minerals in mixtures of hydrofluoric acid and strong acids such as HC1 is catalyzed by H + ions adsorbed at the mineral surface. Studies of the catalyzed dissolution of kaolinite, quartz, potassium feldspar, and sodium montmorillonite have shown that the rates of dissolution can be increased by as much as 900%. The dissolution process can be modeled as simultaneous catalyzed and uncatalyzed reactions, where the surface concentration of H + ions is determined by a Langmuir adsorption isotherm. The degree of catalysis is a strong function of the nature of the silicate surface, a fact which has application in the area of selective dissolution within mixed mineral systems.
Repeat Retinomax screening changes positive predictive value

Purpose To quantify changes in autorefraction measurement with repeated readings using the Retinomax autorefractor and to investigate the clinical implications of the results. Methods Children referred from a preschool vision screening program for a failed autorefraction screening test received repeat autorefraction as well as a comprehensive eye examination with cycloplegic retinoscopy at later follow-up. The intraclass correlation coefficient between initial and follow-up autorefraction was calculated to quantify changes in repeated measurements to determine whether the second autorefraction significantly changed the predictive value that a referred child would meet case definition. Cases were defined by AAPOS Vision Screening Committee amblyogenic risk factors under cycloplegic retinoscopy. Results Repeat Retinomax autorefraction had an intraclass correlation of 0.70 in the right eye and 0.70 in the left eye for mean sphere. Of 636 children who were referred on their initial screening, 169 (26.5%) passed a repeat screening and this subpopulation had 7 cases (4.1%). Of the 467 (73.5%) who again met referral criteria at repeat screening, 268 (57.4%) met case definition. The difference in case rates between these subgroups was highly significant (Fisher exact test, P Conclusions There was clinically significant variability when autorefraction measurements were repeated among those referred from initial screening, allowing further risk stratification. In our study cohort, few children who passed repeat screening required further examination. Significant money and overtreatment risk may potentially be avoided by rescreening children who are initially referred from screening evaluations and only examining those who meet referral criteria after a second screening.
AB INITIO INVESTIGATION OF THE DIELS-ALDER REACTION BETWEEN 2H-PHOSPHOLE AND PHOSPHAETHENE : A MODEL FOR PHOSPHOLE DIMERIZATION

All four possible Diels-Alder reactions between 2H-phosphole and phosphaethene were examined at various theoretical levels, including HF, MP4SDQ, CCSD(T), and CASSCF. MP2/6-31G* geometry optimizations could not be employed since the potential energy surface is qualitatively incorrect at this level of theory, due to the inherent underestimation of the activation energies (ameliorated at higher-order MP or coupled-cluster levels). Solvent effects were examined employing the Onsager, polarized continuum, and isodensity and surface polarized continuum models. At MP4SDQ/6-31G*//HF/6-31G* these reactions are exothermic by 34–38 kcal mol−1 and have very low activation energies, 5–7 kcal mol−1. The PP/CC regioisomer products are lower in energy than the CP isomers and, within each pair, the exo isomer is lower in energy. At low computational levels the smallest activation energy is for the reaction leading to the CP endo product. Larger basis sets, electron correlation, and solvent favor the transition state leading to the experimentally observed PP/CP endo isomer. The dimerization of phosphole is, therefore, kinetically controlled. Based on geometric and electron density analysis, the reactions are concerted and synchronous. © 1997 by John Wiley & Sons, Inc.
Digitization errors using digital charge division positionsensitive detectors

Abstract The data acquisition speed and electronic stability of a charge division position-sensitive detector may be improved by using digital signal processing with a table look-up high speed multiply to form the charge division quotient. This digitization process introduces a positional quantization difficulty which reduces the detector position sensitivity. The degree of the digitization error is dependent on the pulse height spectrum of the detector and on the resolution or dynamic range of the system analog-to-digital converters. The effects have been investigated analytically and by computer simulation. The optimum algorithm for position sensing determination using 8-bit digitization and arithmetic has a digitization error of less than 1%.
The effects of exogenous neuropeptide Y on feeding and sexual behavior in the red-sided garter snake (Thamnophis sirtalis parietalis).

Abstract Actively courting adult male red-sided garter snakes were injected with one of two dosages of neuropeptide Y (NPY) or saline into the third cerebral ventricle. Courtship and feeding responses were assessed prior to surgery, 4–5 h and 24 h post-surgery. Feeding behavior was tested by the presentation of a favored food, an earthworm. NPY significantly reduced courtship behavior scores at both low (0.16 nmol) and high (0.77 nmol) doses 4–5 h after surgery. Snakes also took much longer to reach the criterion courtship score at the high dose. Feeding occurred only in snakes treated with NPY. At the low dose 29% ate at 4–5 h and 24 h after surgery; 43% of the snakes treated with the high dose ate 4–5 h post-surgery. When tested the day following injection, animals were courting at levels comparable to presurgery levels and refused food.